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Review

Research on Phase Change Cold Storage Materials and Innovative Applications in Air Conditioning Systems

by
Zhengjing Li
,
Yishun Sha
and
Xuelai Zhang
*
Merchant Marine College, Shanghai Maritime University, Shanghai 201306, China
*
Author to whom correspondence should be addressed.
Energies 2024, 17(17), 4365; https://doi.org/10.3390/en17174365
Submission received: 24 July 2024 / Revised: 16 August 2024 / Accepted: 30 August 2024 / Published: 31 August 2024
(This article belongs to the Section D: Energy Storage and Application)
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Abstract

:
Phase change cold storage materials are functional materials that rely on the latent heat of phase change to absorb and store cold energy. They have significant advantages in slight temperature differences, cold storage, and heat exchange. Based on the research status of phase change cold storage materials and their application in air conditioning systems in recent years, this paper provides an overview of the materials and their enhanced research progress. It summarizes the types of phase change cold storage air conditioning systems, optimization schemes, and system applications. This paper also identifies the current issues in phase change cold storage air conditioning and discusses the development trends in cold storage materials and air conditioning systems. It anticipates that future advancements will focus on composite phase change cold storage materials and low-energy consumption intelligent phase change cold storage air conditioning systems in steam compression using spherical capsules and concave–convex plate PCM.

1. Introduction

Since the beginning of the 21st century, rapid global economic development and population growth have led to a steady expansion of energy consumption demands. However, this has exerted tremendous pressure on global energy resources, rapidly rising energy costs and exacerbating the imbalance between resource availability and social development. Consequently, alleviating energy constraints and achieving sustainable development have become significant challenges worldwide. Notably, air conditioning systems account for 50% to 60% of energy consumption in public buildings [1,2], while power supply exhibits temporal and spatial imbalances characterized by significant peak-to-off-peak disparities. Furthermore, the International Energy Agency predicts that global demand for air conditioning will continue to grow, potentially increasing by over five times by 2050. Consequently, addressing the growing demand for air conditioning while mitigating the temporal and spatial mismatch between energy supply and demand has become an urgent and critical issue. In this context, the study of green and low-energy air conditioning systems holds significant practical significance in alleviating energy constraints.
To regulate peak electricity loads, cold storage technology can address the mismatch between air conditioning demand and energy supply [3,4]. By storing cooling capacity during low-demand or low-cost energy periods and supplying it during high-demand peak load periods, this technology also holds promise for achieving a higher proportion of renewable energy utilization and mitigating intermittent fluctuations, thereby alleviating energy constraints. The peak shaving and valley filling schematic diagram is shown in Figure 1. Air conditioning cold storage technology includes three main types: sensible heat storage, latent heat storage, and chemical reaction heat storage [4,5]. Sensible heat storage is valuable for altering temperatures without inducing phase changes, which is beneficial for straightforward heating or cooling processes.
On the other hand, latent heat storage excels by enabling phase transitions, offering an efficient means of thermal energy retention and discharge. However, their application in air conditioning cold storage is limited due to the high risks and substantial investment associated with chemical reactions. Specifically, as indicated in Table 1, cold storage technology in air conditioning systems can be differentiated based on the storage medium, which can be divided into water, ice, and phase change cold storage (excluding ice). Water-based cold storage relies on sensible heat and is frequently used. However, it has the drawbacks of a low cold storage density and higher maintenance costs. Ice-based cold storage utilizes the latent heat for cold storage and, compared to water, requires less space and offers a greater density. Yet, the system is more complex, and the evaporation temperature needs to be lowered to below −6 °C [6], which can result in increased energy consumption and reduced operational efficiency by 30% to 40% [7]. To summarize, phase change cold storage addresses the problems of large storage tank volumes [8] and the low efficiency associated with water and ice cold storage systems.
In air conditioning cold storage systems, the application of phase change materials (PCMs) is considered to enhance both system energy efficiency and reduce initial investment costs, as suggested by Yang [9], and Riahi et al. [10] found that the incorporation of PCMs can increase the cooling capacity from 39.67% to 54.60% and improve the coefficient of performance (COP) from 14.68% to 20.7%. Ma [11] calculated that phase change cold storage consumes less energy and offers more flexibility in selecting evaporation temperature compared to ice-based cold storage, indicating a better application prospect. Zhao et al. [12] built a physical system to test the energy-saving efficiency of phase change cold storage air conditioning. They discovered that when the indoor–outdoor temperature difference is 7 °C, using PCM for cold storage can save 35.3% of electrical energy. Therefore, latent heat cold storage holds more excellent research value in the field of cold storage air conditioning than sensible heat cold storage. In addition to phase change cold storage materials, the system configuration of cold storage air conditioning is also crucial. Phase change cold storage air conditioning systems can reduce energy consumption and improve energy utilization rates [13]. However, various types are available, such as vapor compression and natural cooling systems. Consequently, the selection of phase change cold storage materials and phase change air conditioning systems has become the most critical topic to minimize the energy consumption of air conditioning [14].
Drawing from the recent advancements in phase change cold storage materials and their integration into air conditioning systems, this review offers a comprehensive examination of the current state of these materials and the enhancements observed in their research. It describes the various categories of phase change cold storage air conditioning systems, the strategies employed for their optimization, and the practical applications of these systems in real-world scenarios. This paper critically addresses the existing challenges within the phase change cold storage air conditioning realm, engaging in thoughtful discourse on future developments. It posits that forthcoming research will likely concentrate on the innovation of composite phase change cold storage materials, which promise superior thermal performance and energy efficiency. Additionally, this review highlights the potential for the emergence of intelligent phase change cold storage air conditioning systems that operate with minimal energy consumption, particularly those that leverage the properties of spherical capsules and concave–convex plate PCM in steam compression processes. These advancements are expected to pave the way for more sustainable and efficient cooling solutions, aligning with the growing demand for green technologies.
Table 1. Performance comparison of water, ice, and phase change cold storage [15].
Table 1. Performance comparison of water, ice, and phase change cold storage [15].
SpecificationWater Cold StorageIce Cold StoragePhase Change Cold Storage
Specific heat
J/(kg·K)		4.192.04-
Latent heat (kJ/kg)-33480~250
Maintenance costsHigherModerateModerate
Cold storage tank capacityLargerSmallerModerate
Power consumptionLowerHigherLower
Initial investmentLowerModerateHigh
Technical requirements and operating costsHigh technical requirements and high operating costsLow technical requirements and low operating costsHigh technical requirements and low operating costs
Coefficient of performance 5.0~5.92.9~4.15.0~5.9

2. Phase Change Cold Storage Materials and Their Enhancement

The working principle of phase change cooling is based on using PCMs that absorb or release a large amount of latent heat during their phase transition to store or release cold energy. When the PCM melts, it draws heat from the surroundings, cooling the area; when it solidifies, it releases the stored heat to maintain the lower temperature. Temperature fluctuations significantly affect the thermophysical properties of PCM. The highest operating temperature for PCMs is determined by their melting point, which is the temperature at which the material transitions from solid to liquid. Beyond this temperature, the PCM can no longer absorb additional heat. Conversely, the lowest operating temperature is typically limited by the PCM’s freezing point, the temperature at which it transitions from liquid back to solid. Below this point, the PCM cannot release heat. As temperatures rise, the density of PCM changes due to the volume differences between solid and liquid states, while its viscosity decreases. Moreover, the thermal conductivity of PCM tends to increase with temperature, which aids in more efficient heat transfer.
PCM face several challenges and limitations in their widespread application. Initially, cost is a significant barrier, particularly for large-scale uses where economic viability is critical. Secondly, the low thermal conductivity of PCMs restricts heat transfer efficiency, often necessitating additional mechanisms to enhance performance. Additionally, risks of leakage and phase separation can affect the long-term stability and reliability of thermal cycling. The volume changes that PCMs undergo during phase transitions impose special design requirements for containment vessels, while material compatibility issues are crucial for the durability of the entire system. Environmental impact is also an important consideration, as some PCMs may contain components harmful to the environment. Furthermore, the adaptability of PCMs to specific applications requires their phase change temperatures and thermophysical properties to align with the temperature requirements of the application scenario, which to some extent limits their broad application.
The commonly used phase change materials for air conditioning cold storage are solid–liquid phase change materials, which can be divided into pure materials and composite phase change cold storage materials, as depicted in Figure 2. Among these, the thermophysical properties of PCM have the most significant impact on the cold storage effect, particularly the latent heat of phase change [16].

2.1. Pure Phase Change Cold Storage Materials

2.1.1. Inorganic Phase Change Cold Storage Materials

Inorganic phase change cold storage materials include salt hydrates and metallics, known for their high thermal storage capacity and thermal conductivity. Standard inorganic phase change cold storage materials are listed in Table 2. Latent heat pairs are shown in Figure 3. However, inorganic phase change cold storage materials are highly prone to supercooling and phase separation, and they tend to lose their thermal properties after extensive thermal cycling [13]. These issues pose significant limitations to inorganic phase change materials in cold storage applications. Nonetheless, researchers have identified that incorporating appropriate additives can mitigate supercooling and phase separation phenomena.
Supercooling is when a substance cools down to a temperature below its freezing point without actually solidifying. Three principal strategies have been employed to address supercooling: (1) Nucleating agent method [15]. This approach involves providing a solid or gaseous nucleus to facilitate phase change. Lin et al. [17] discovered that the incorporation of nucleating agents, thickeners (CMC), and cooling agents (NH4Cl and KCl), into sodium sulfate decahydrate (SSD) can effectively suppress supercooling. Chen et al. [18] observed that adding nucleating agents, such as powdered borax, could significantly reduce supercooling. Yang [9] reported that a 3% addition of borax was optimal for eliminating supercooling. Liu et al. [19] found that using diatomaceous earth at 0.1% and 0.2% as a nucleating agent resulted in a phase change temperature of −4.06 °C and a phase change latent heat exceeding 300 kJ/kg, effectively inhibiting supercooling. Yang et al. [20] developed a composite phase change material, SSD-BPA/EG, by incorporating expanded graphite into SSD-BPA. With a mass ratio of 93:7, the material exhibited a phase change temperature of 7.4 °C, a phase change latent heat of 117.4 J/g, and a thermal conductivity of 1.876 W/(m·K), with a reduced degree of supercooling. In addition to direct nucleating agent incorporation, Wang et al. [21] found that phase change nanofluids could enhance nucleation, effectively acting as nucleating agents. Yan et al. [22] noted that higher concentrations of nanofluids could accelerate ice crystal formation and diminish supercooling. Experiments indicated that water-based carbon nanotubes could promote nucleation, compared to water, reducing supercooling by 48.9%, shortening the nucleation time by 48.8%, and decreasing the total cold storage time by 23.8%. (2) Particle viscosity method: This technique aims to minimize the interstitial spaces between macroscopic particles. Chen et al. [18] found that the cellulose molecules of sodium carboxymethyl cellulose could connect through hydrogen bonds and water molecules, thereby constricting the macroscopic movement of particles and increasing their viscosity, which in turn reduces supercooling. (3) Polymer method: This involves the addition of polymers to the system. Liu et al. [23] demonstrated that the inclusion of eutectic saltwater (a solution of potassium chloride and ammonium chloride) into superabsorbent polymers (SAP) could effectively weaken supercooling.
Two primary methods have been proposed to address phase separation: (1) Thickener method: This approach seeks to increase the viscosity of the solution. Yang [9], in his study of sodium sulfate decahydrate, found that the addition of 1.0% to 2.0% (wt) of polyacrylic acid sodium (PAAS) as a thickener could effectively mitigate phase separation. Moreover, a 2% (wt) addition of PAAS had a minimal impact on the latent heat. Experiments revealed that a combination of 2% (wt) PAAS and 14% NH4Cl could maintain the phase change temperature of sodium sulfate decahydrate at 7.5 °C, effectively inhibiting phase separation and aligning with the typical cooling temperatures of contemporary air conditioning systems. (2) Mixing method: This involves blending the material with other substances. Li et al. [24] created a composite inorganic salt phase change material by mixing Na2SO4·10H2O and Na2HPO4·12H2O. They observed that a mass ratio of 4:6 significantly reduced phase separation compared to pure Na2SO4·10H2O, with a phase change temperature ranging from 6.1 to 6.3 °C and a phase change latent heat of 130 to 139 J/g, indicating a minimal phase separation effect.
Table 2. Some typical PCMs used in inorganic phase change cold storage and their physical properties parameters; data from [25].
Table 2. Some typical PCMs used in inorganic phase change cold storage and their physical properties parameters; data from [25].
PCMPhase Change Temperature (°C)Latent Heat (kJ/kg)ApplicationReferencesCosts(CHF)
Na2SO4·10H2O (NH4Cl, borax, PAC)10.3142.7Air conditioning[26]278
Na2SO4·10H2O (NH4Cl, KCl, K2SO4, CMC, sodium hexametaphosphate borax, and boric acid)8.25114.4Air conditioning[27]713
Inorganic hydrates are encapsulated within high-density polyethylene (HDPE) cold storage plates8182Air conditioning[28]519
Na2SO4·10H2O (NH4Cl, TiO2 nanoparticles, silica gel powder)7.33135Air conditioning[29]450
A 15% solution of NaCl−11153Freezing cabinets[30]165
A mixture of sodium formate, potassium chloride, and distilled water with concentrations ratioed at 22%:8%:70%−23.8250.3Freezers[31]722
NaCl acts as the primary energy storage medium; K2CO3 and KCl are employed as cooling agents−24200Refrigerated transport[32]324
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Figure 3. The latent heat of typically used inorganic phase change materials for thermal energy storage (kJ/kg) [26,27,28,29,30,31,32]. (The different color represents the highest latent heat).
Figure 3. The latent heat of typically used inorganic phase change materials for thermal energy storage (kJ/kg) [26,27,28,29,30,31,32]. (The different color represents the highest latent heat).
Energies 17 04365 g003

2.1.2. Organic Phase Change Cold Storage Materials

The thermophysical parameters of typical organic phase change materials for cold storage are presented in Table 3. Latent heat pairs are shown in Figure 4. Organic phase change materials exhibit lower corrosiveness and are less prone to supercooling and phase separation phenomena than inorganic phase change materials. However, they generally have lower latent heat and thermal conductivity. Lv [33] utilized differential scanning calorimetry to discover that the properties of tetradecane and pentadecane align well with the standards for pure organic cold storage materials, and the performance of decanol also meets these criteria. Additionally, embedded ribs can improve thermal conductivity, but the height of the ribs significantly influences their effectiveness. A rib-to-wax height ratio greater than 0.975 is considered appropriate. Metal foam, fins, nanoparticles, or effective encapsulation can also enhance thermal conductivity. Beyond paraffin, Rodríguez et al. [34] found that pig fat is an incombustible organic phase change material with a maximum heat gain of 1.51 W/m2 and a heat loss of −2.22 W/m2. This highlights the potential for utilizing various organic materials in cold storage applications, each with its unique set of properties that can be optimized for specific thermal performance requirements.

2.2. Composite Phase Change Cold Storage Materials

Typical composite phase change cold storage materials are listed in Table 4. Latent heat pairs are shown in Figure 5. Composite phase change materials overcome the drawbacks of both inorganic and organic cold storage materials, with less pronounced phase separation and supercooling issues. Moreover, Waqas et al. [46] found that composite phase change materials for cold storage can shift the majority of peak loads to off-peak times, making them more practical for cold storage than pure materials and leading to a more balanced distribution of peak and off-peak electricity usage. Lv [33] discovered through differential scanning calorimetry that binary mixture phase change materials composed of isopropyl myristate and hexadecane, dodecanol and capric acid, dodecanoic acid and myristic acid, and myristic acid with tetradecane are more aligned with the standards for cold storage materials. However, phase change materials still face issues of leakage and corrosion. Micro/nanocomposite phase change materials have been widely researched and applied due to their lower environmental reactivity and controllable volume changes during phase change. Still, their current problems include high cost, limited availability, and incompatibility with inorganic phase change materials [47,48,49]. Fortunately, as shown in Table 5, Chang et al. [50] found that ceramic-based composite phase change materials possess excellent corrosion resistance and high thermal conductivity and can utilize both the latent heat of phase change materials and the sensible heat of ceramics to achieve high thermal storage density.
In summary, the supercooling issue of inorganic phase change cold storage materials can be addressed using the nucleating agent method to facilitate phase change, effectively controlling the degree of supercooling to below 2 °C [25]. The phase separation problem can be mitigated by employing the thickener method to increase the viscosity of the solution. Among inorganic phase change cold storage materials, a novel composition with a high latent heat of fusion is the mixture of sodium formate, potassium chloride, and distilled water with concentration ratios of 22%:8%:70%, which can reach up to 250.3 kJ/kg [31]. For organic phase change cold storage materials, adding copper wires and ribs can enhance thermal conductivity. Pig fat has been found to have a heat gain of up to 1.51 W/m2 [34], and a novel composition with a high latent heat of fusion is the mixture of lauric acid and tetradecane with a molar ratio of 21:79, which can reach up to 209.42 kJ/kg [41]. Composite phase change cold storage materials have outperformed pure materials in terms of cold storage capacity. A novel and effective composite formulation with high latent heat of fusion contains 2% potassium chloride, 1.37% glycine, and 3.37% superabsorbent polymer (SAP), which can achieve up to 318.14 kJ/kg [56].
Energies 17 04365 g004
Figure 4. The latent heat of typically used in organic phase change materials for thermal energy storage (kJ/kg) [3,36,37,38,39,40,41,42,43,44,45]. (The different colors mean that, upon comprehensive consideration, not only is the latent heat relatively high, but the research content is also relatively new).
Figure 4. The latent heat of typically used in organic phase change materials for thermal energy storage (kJ/kg) [3,36,37,38,39,40,41,42,43,44,45]. (The different colors mean that, upon comprehensive consideration, not only is the latent heat relatively high, but the research content is also relatively new).
Energies 17 04365 g004

2.3. Cost–Benefit Analysis for PCMs

The economic viability of PCM is influenced by initial investment costs, operational expenses, maintenance fees, and the total lifecycle costs over their usage period. Although the initial cost of PCM may be high, their superior energy efficiency in reducing reliance on conventional cooling or heating systems leads to significant long-term savings on energy consumption and expenses. The low maintenance requirements of PCM systems further cut operational costs. Additionally, the environmental benefits, such as reduced greenhouse gas emissions, could translate into economic incentives like carbon credits. As production scales up, economies of scale will lower the unit cost of PCM, enhancing its market competitiveness. Technological advancements and the high energy efficiency demands of specific applications also positively affect the cost–benefit ratio of PCM, making it a promising option for cost savings and energy efficiency improvements in the long run.
Cost–benefit analysis has been used in many areas, such as solar photovoltaic systems, renewable energy systems and tidal energy production. In the realm of cost–benefit analysis, key decision-making metrics encompass the net present value (NPV), benefit/cost ratio (BCR), internal rate of return (IRR), and payback period (PR). Detailed computations for these methodologies are delineated in subsequent references. The cost-effectiveness is to be determined using the relevant formulas, with a fixed interest rate of 10% and a system life span of 10 years [28]. The benefit and cost analysis of systems with and without phase change thermal storage is as shown in the Table 6.

3. Case Study

3.1. Vapor Compression Phase Change Cold Storage Air Conditioning System

Vapor compression phase change cold storage air conditioning systems still comply with vapor compression refrigeration’s basic principles with mechanical equipment. Still, they incorporate phase change materials and components to use the latent heat of phase change for cooling. Said et al. [60] studied the performance of mixed systems (with both phase change and vapor compression refrigeration units), cold storage systems, and vapor compression refrigeration unit systems, as is shown in Figure 6. The experiments showed that in the summer, the COP of the mixed system could increase by up to 88%, and the COP of the phase change cold storage system was about 50%. However, compared to systems without PCM, both the mixed and single systems saw an increase in energy savings of 6.5% and 6.85%, respectively. Vapor compression phase change cold storage air conditioning systems can be divided into three configurations where PCM is applied: condenser, cold storage tank, and evaporator.

3.1.1. PCM Applied in Condenser for Phase Change Cold Storage Air Conditioning Systems

The application of PCM in the condenser of phase change cold storage air conditioning systems can capture the heat discharged by the refrigerant, subsequently diminishing the subcooling extent and the condensing temperature, which in turn reduces the work required from the compressor. This strategy not only lightens the thermal burden on the condenser but also augments its overall energy efficiency, as reflected by an elevated COP. Singh et al. [61] directed hot air to flow through a cylindrical pipe enveloped by PCM, allowing for a portion of the thermal energy to be absorbed by the PCM. They concluded that the phase change time could be shortened by 31.59% through numerical analysis.

3.1.2. PCM Applied in Cold Storage Tank for Phase Change Cold Storage Air Conditioning Systems

The integration of PCM in thermal energy storage units within air conditioning systems facilitates the storage of substantial amounts of cold energy with minimal temperature fluctuations. These units can then release cold energy during periods of high demand, effectively managing load on the system and conserving energy. By alleviating the workload on components such as the compressor, PCM-based thermal storage units also contribute to reduced maintenance costs. PCM used in the cold storage tank of phase change cold storage air conditioning systems can be configured in series or parallel with the vapor compression refrigeration unit. Feng [8] established three system models to compare performance: single refrigeration unit cooling, as illustrated in Figure 7, single cold storage tank cooling, and combined cooling from the refrigeration unit and cold storage tank. It was found that under the condition of whole night-time cold storage, the combined cooling system could save 45% of energy costs. Ma [11] found that before phase change, the suspension liquid in the cold storage tank would increase in mass concentration while the amount of cold storage decreased. However, after reaching the phase change temperature, the suspension liquid with a higher mass concentration cooled down more quickly. Therefore, overall, the cold storage performance of high-concentration suspension liquid is superior to that of low-concentration. Gao [62] established a model to study the solidification and melting process of cold storage tank droplets and found that temperature has a significant impact compared to flow rate and nozzle diameter. During cold storage, the amount of cold storage is directly proportional to the temperature and flow rate of the cold storage agent and inversely proportional to the inlet temperature of the cold carrier. During heat release, the heat release is directly proportional to the inlet temperature of the cold carrier and inversely proportional to the initial temperature of the cold storage tank. Zeng et al. [63] and Wang et al. [64] tested the impact of various factors on the cold storage performance of cold storage tanks. They found that the factors most affecting heat release performance are pipe thickness, wind speed, and ambient temperature, with thermal conductivity having a minimal impact on heat release performance. Jia et al. [65] studied the effect of water temperature rise in the cold storage tank on air conditioning performance, as shown in Figure 8. The experiment showed that using PCM in the water tank could improve the performance coefficient by 6.9% to 9.8% and extend the insulation time of the water tank by 21.1%.
Zhao et al. [66] designed a shell-and-tube PCM cold storage tank, as shown in Figure 9, where the space between the finned inner and outer tubes is filled with PCM. During the daytime air conditioning cooling period, it plays a role in heat dissipation and cold storage, the stored cold in the PCM is released at night. Experiments showed that the COP of the air conditioning system with the cold storage tank was higher than 0.5, and the COP increased by about 25.6% compared to commonly used water-cooled air conditioning. As shown in the Figure 10, Wan et al. [67] designed a phase change cold storage air conditioning system for split air conditioners. The principle is to collect condensate during the day, causing the PCM to undergo phase change and store cold. At the same time, the condensate can absorb heat by spraying on the evaporator surface, reducing the condensation temperature and improving the cooling coefficient and only the fan is turned on. The film formed by the filtered condensate will exchange heat with the driven air. After the air’s heat is absorbed, the cooling effect at night can be achieved. After numerical analysis, the system’s energy-saving rate reached 2.1%, and 24.6 kWh of electricity can be saved during the peak air conditioning season. Nguyen [68] approached the issue from recovering waste heat and cold storage, constructing a thermal and cold storage system, as shown in Figure 10. The thermal storage system is equipped with a double-pipe heat exchanger in the compressor’s exhaust pipeline, providing a temperature difference range of 3–4 °C between the inlet and outlet heat transfer fluids, capable of supplying 50 L of hot water at 60 °C per hour. The phase change material is a mixture of glycerin and water. During the experiment, the initial material temperature was 29.9 °C, which dropped to 28.4 °C after 20 min of loading, to 19.6 °C after 120 min, and to −3.1 °C after 420 min. The temperature of the cold storage material shows a downward trend over time, and the cover of the storage tank prevents heat transfer to the environment, causing the energy stored in the cold storage tank to increase gradually.

3.1.3. PCM Applied in Evaporator for Phase Change Cold Storage Air Conditioning Systems

Incorporating PCM into the evaporator of an air conditioning system enables the absorption of environmental heat, thereby enhancing cooling efficiency. By reducing the frequency of compressor startups and shutdowns, PCM also facilitates continued cooling even after the compressor has been deactivated, thus reducing its operating time. It contributes to providing additional cooling capacity, conserving energy, and potentially downsizing system components [69]. Loem et al. [70] found through numerical analysis that the best energy efficiency is achieved when the PCM layer thickness is 0.08 to 0.24 m and the cooling time is 228 to 411 min, saving 1.58 to 13.84% of electrical energy per day. Chaiyat [71] constructed a prototype of a phase change cold storage air conditioner that combines PCM spheres with the evaporator, as shown in Figure 11. Compared to conventional air conditioning, the experiment showed that combining PCM spheres and the evaporator can save 9% of electrical energy.

3.2. Natural Cooling Phase Change Cold Storage Air Conditioning Systems

Compared to traditional refrigeration systems, natural cooling phase change cold storage air conditioning systems utilize the natural temperature differences between day and night and the properties of phase change materials to achieve cooling effects without mechanical equipment. Abdolmaleki [13] summarized the natural cooling phase change cold storage air conditioning systems into two modes. The first mode occurs on summer evenings when the lower outdoor air temperature allows for the phase change material to store coldenergy, which can also be supplied indoors. The second mode occurs during summer days when the indoor hot air is absorbed by the PCM, causing it to undergo a phase change, lowering the indoor temperature and achieving a cooling effect. As illustrated in Figure 12, Wonorahardjo et al. [72] filled 80 plastic cylindrical containers with coconut oil or water as phase change materials, creating an air conditioning system that consumes no mechanical or electrical energy. During the day, the air is cooled by the phase change materials, at night, the phase change materials release heat to the outdoors, reducing the indoor temperature, thus enhancing the cooling effect and reducing energy consumption.

3.3. Optimization of Phase Change Cold Storage Air Conditioning System

Feng [8] obtained through simulation that the total energy consumption for the cold storage tank alone using phase change cold storage technology and the combined cooling from the cold storage tank and refrigeration unit were 58,364.13 kW·h and 66,836.16 kW·h, respectively, compared to the energy consumption of 39,932.31 kW·h for traditional chilled water unit air conditioning systems, which is an increase of 46.15% and 67.3%. Therefore, although phase change cold storage air conditioning systems balance the power grid and have good economic benefits, they consume more electrical energy and may not achieve the goal of energy saving.
To further save energy, phase change cold storage air conditioning systems can be optimized from the following six aspects: refrigerant charge, enclosure structure, application of TES heat storage modules, storage form of PCM, inherent properties of PCM, and fins, thereby achieving higher efficiency and reducing more energy consumption. The optimal refrigerant charge can improve the efficiency and performance of the system, reducing energy consumption. Through numerical analysis, Wu et al. [73] studied the performance of conventional air conditioning refrigeration and air conditioning cold storage under different refrigerant charges. As the charge increases, the COP for both conditions first increases and then decreases; the optimal refrigerant charge for the air conditioning cold storage condition is 1200 g, which is 75% of the optimal charge for the conventional air conditioning condition (1600 g); when the charge is between 1200 g and 1600 g, the impact on the traditional air conditioning condition is more significant than that on the air conditioning cold storage condition. Therefore, for phase change cold storage air conditioning, the optimal refrigerant charge should be determined comprehensively considering the usage time of both conditions.
Optimizing the enclosure structure can reduce heat exchange losses, thereby reducing the load and energy consumption of the air conditioning system. Zhou et al. [74] installed SSPCM boards on all exterior wall surfaces of the system, reducing energy consumption by 11% and system costs by 20%. Using PCM heat storage modules can also reduce the load and energy waste. Nie et al. [75] compared the performance of TES systems containing phase change materials with traditional air conditioning. Due to the spherical PCM capsules being in direct contact with the chilled water, there is less heat exchange loss and energy consumption. Goyal et al. [76] created a TES module composed of 10 graphite tetradecane composite boards with alternating discharge (heat) and charge (cold) fluid circuits, as illustrated in Figure 13, using a glycol–water mixture as the charge-discharge fluid. Chen et al. [77] developed an auxiliary calculation model to calculate the best settings for TES systems under different climatic conditions, increasing the seasonal energy-saving rate from 16.9% to 50.8%.
There are various types of PCM storage units in air conditioning systems, and each type offers different benefits [78]. Almeshaal et al. [79] found that filling nanoparticles such as Al2O3 into spherical capsules can enhance phase change, achieving the same amount of cold storage with only 36% to 77% of the original cold storage time, providing the best efficiency. As shown in Figure 14, Ismail et al. [80] discovered that PCM encapsulated in concave/convex plates and integrated into air conditioning equipment could reduce the solidification time of PCM and improve the air conditioning performance. Compared to PCM in a regular flat plate, PCM in a concave–convex plate can achieve the highest average energy saving rate of 6.5%, with an overall improvement of 16%. The energy transmission rate (AC power) of PCM concave–convex plates saved about 16% and 7.5% after operating for 120 min and 300 min, respectively. Regarding the inherent properties of PCM, Parameshwaran et al. [81] found that phase change materials with silver nanoparticles can significantly enhance system performance, with potential energy savings ranging from 24% to 51% over a day. Deng et al. [82] concurred with this finding. Additionally, they noted that air conditioning systems with such spherical capsules placed at the evaporator are consistently more efficient than traditional air conditioning systems.
Fins can increase the heat transfer surface area, promote heat transfer, reduce energy consumption, and improve air conditioning systems’ cooling effects and performance. Yan et al. [22] found that the melting time with fins could be reduced by 24.0%, the discharge rate increased by 74.4%, the discharge capacity increased by 63.5%, and the ice melting rate reached 94.6%, enhancing the thermal conductivity of phase change materials [83]. Embedding fins in the casing, regardless of the type, can improve heat transfer [82]. However, such casings may also reduce the heat transfer rate and even alter the material’s mechanical properties [84]. Zhao et al. [66] used numerical simulation to analyze the combination of shell and tube with fins and found that the COP could be increased by up to 25.6% with their combined use. Nie et al. [75] further discovered that TES devices perform better with fins. Compared to not using fins, two air-side fins reduced the cold storage time by 74% and the heat release time by 85%. Li et al. [85] simulated the process with a mathematical model and found that not only was the COP increased, but the cost was also reduced. Chaiyat [71] applied PCM spherical capsules in air conditioning and found that the normal system payback period is approximately 4.12 years, while TES with PCM could save about 9% of electricity. The application of fins in PCM-based systems demonstrates their potential to enhance the efficiency and economic viability of these technologies.
To optimize the utilization of phase change thermal storage air conditioning, it is crucial to monitor the durability and potential degradation of the PCM. Internally, sensors can be installed to measure pressure, temperature, and weight, providing real-time data on the PCM’s state. Externally, instruments such as thermal imaging cameras can be employed to observe temperature distributions, facilitating the monitoring and detection of any anomalies.

3.4. Application of Phase Change Cold Storage Air Conditioning

Currently, the new energy source that is often integrated with air conditioning is solar energy. However, Li et al. [86] found that photovoltaic (PV) direct-driven air conditioning is significantly affected by the fluctuation of solar energy, as illustrated in Figure 15, leading to a lack of flexibility in energy matching between air conditioning load demand and PV power generation. The incorporation of PCM can mitigate the issue of large fluctuations in solar radiation values and improve energy utilization efficiency. If the PCM is appropriately selected, it is possible to achieve a 90% probability of zero energy consumption [87].
As shown in Figure 16, Loem et al. [69] investigated a phase change cold storage air conditioning system powered by PV: when the solar radiation intensity is not high enough, the power grid supplies the air conditioning; when the solar radiation intensity is high, the air conditioning is powered by PV. During the night or off-peak hours when air conditioning is not in use, the 5 °C air from the evaporator coil causes the PCM to solidify, during the cooling period, the air is precooled by the PCM, reducing the cooling load on the evaporator and thus lowering the system’s electrical energy consumption. Compared to conventional air conditioning, this system can save 16.13% of electrical energy during summer. In an ideal scenario where only PV power is used, the system could save up to 84.62% of electrical energy.
As shown in Figure 17, Qi et al. [88] designed a phase change cold storage solar-powered vehicular air conditioning system consisting of two main components: a solar energy collection and storage module and a phase change cold storage module. After solar energy is collected, it is converted into electrical energy and stored in supercapacitors to power the air pump and water pump. Air enters the system through the air pump and then passes through the PCM section. The PCM undergoes phase change due to the action of water, which cools the air. Experiments showed that the maximum output power of the solar module is 2.181 W, and the best cooling effect is achieved when the temperature difference between the inlet and outlet air reaches 30 °C.
Sun [89] simulated a double-layer phase change energy storage floor with capillary tube solar hot water radiant air conditioning. The combination of phase change materials with traditional capillary network solar hot water radiant air conditioning showed that the system’s energy storage time was significantly reduced, capable of meeting the demand for 8 h of energy storage and 16 h of energy release in summer, with the floor surface temperature reaching 296 K and below. As shown in Figure 18, Zheng et al. [90] developed a solar air conditioning system using microencapsulated PCMs and found that the intensity of solar radiation is directly proportional to the efficiency of vacuum tube collectors. When the temperature inside the microencapsulated PCM cold storage tank is above 10 °C, the system operates as a conventional air conditioner, with the compressor cooling. This causes the liquid in the storage tank to cool down to the phase change temperature, after which the microencapsulated PCM cold storage tank begins to store cold and supply cooling, creating a cycle. The system can maintain the room temperature between 18 °C and 20 °C with minimal fluctuations. Even when solar radiation is unstable, the system can still operate and supplement cold energy with an energy-saving rate as high as 30.5%.
As shown in Figure 19, Ahmed et al. [91] proposed an air conditioning system that can store cold using only renewable energy sources. The system solely relies on photovoltaic panels on the exterior walls to power the thermoelectric system on the interior walls. Double phase change material layers are used to extract heat from the photovoltaic panels and the thermoelectric cooling system. The photovoltaic panels are used to drive the thermoelectric cooler (TEC) system. Simulations indicate that the minimum COP of the system can also reach 2.
PCMs have emerged as a promising solution for enhancing the efficiency and reliability of cold chain transportation [92]. Shafiei et al. [93] designed a smart hybrid system that pairs a cooling unit with a heat bank. It cools the cargo area and tops up the PCM’s heat energy when the truck goes faster than a set speed, cutting energy use by 17% compared to more traditional ways.

4. Discussion and Conclusions

This article conducted a detailed literature review on phase change cold storage air conditioning, collecting information on phase change materials and their enhancement research, as well as data on phase change cold storage air conditioning systems, and summarized the effects from the perspective of reducing air conditioning energy consumption. Overall, the various applications of phase change materials in cold storage air conditioning can reduce air conditioning energy consumption and improve energy efficiency. Therefore, phase change cold storage air conditioning is a future development direction for air conditioning energy saving, and the following conclusions can be drawn:
  • Latent heat cold storage holds greater research potential in air conditioning than sensible heat due to its high energy storage efficiency. Selecting appropriate phase change materials is essential, supercooling in inorganic materials can be mitigated with nucleating agents, and thickeners can prevent phase separation. Copper wires and ribs enhance the thermal conductivity of organic materials, while composite materials overcome the limitations of pure substances, pointing to a vital direction for future development. Vapor compression systems, which integrate phase change materials into condensers, storage tanks, and evaporators, are well established. Natural cooling systems leverage ambient conditions for low-energy cooling. Vapor compression is preferred for rapid, efficient cooling; however, natural cooling is ideal in suitable climates to minimize energy use.
  • Energy consumption reduction can be approached from aspects such as refrigerant charge, enclosure structure, application of TES heat storage modules, PCM storage, inherent properties of PCM, and fins. The best phase change cold storage air conditioning performance is achieved when PCM is installed in spherical capsules or concave–convex plates and combined with the evaporator. However, further reducing the energy consumption of phase change cold storage air conditioning remains a crucial research topic for the future.
  • Phase change materials often have issues such as leakage and corrosion. Therefore, good encapsulation is crucial for improving thermal reliability, good sealing, and strong resistance to thermal expansion. Composite phase change materials always perform better than pure materials. Ceramic-based composite phase change materials have excellent corrosion resistance and high thermal conductivity. Therefore, finding new composite phase change materials is a direction to solve the problems mentioned above.
  • The practical application of phase change cold storage air conditioning systems at a large scale entails a careful evaluation of various factors, including cost-effectiveness, environmental impact, and the complexity of the processes involved. Despite the technological advancements in this field, the literature on these critical aspects remains sparse, indicating a clear gap that warrants further investigation. Furthermore, the research on using phase change cold storage air conditioning with new energy sources is relatively limited. While the integration with solar energy has been more extensively documented, a substantial opportunity exists for future development in the joint application of other renewable energy sources. This area of research holds promise for enhancing the sustainability and efficiency of cold storage air conditioning systems and, thus, deserves increased attention and exploration.
  • Technological progress is set to usher intelligent features into phase change cold storage air conditioning systems. These systems will employ intelligent temperature control and thermal regulation, automatically adjusting the phase change and cooling output in response to environmental conditions and human activity, minimizing energy waste and cutting consumption. Integrating smart home ecosystems will allow for users to manage their air conditioning via mobile apps or voice commands, enhancing convenience and efficiency.
  • Regarding phase change cold storage materials, research and development focusing on bio-based materials, such as plant and animal fats, could help reduce material costs. Combining shape memory alloys with PCMs to initiate phase change through shape alteration at specific temperatures shows promise. Using microchannel heat exchangers could boost heat transfer efficiency, creating modular, easy-to-maintain units. Features like fire protection, noise reduction, and air purification could further enhance system performance.

Author Contributions

Writing—original draft preparation, Z.L.; writing—review and editing, Y.S.; supervision, X.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Data Availability Statement

Data will be made available on request.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Taheri, S.; Amiri, A.J.; Razban, A. Real-world implementation of a cloud-based MPC for HVAC control in educational buildings. Energy Convers. Manag. 2024, 305, 118270. [Google Scholar] [CrossRef]
  2. Chen, Y.; Liu, Y.; Liu, J.; Luo, X.; Wang, D.; Wang, Y.; Liu, J. Design and adaptability of photovoltaic air conditioning system based on office buildings. Sol. Energy 2020, 202, 17–24. [Google Scholar] [CrossRef]
  3. Selvnes, H.; Allouche, Y.; Manescu, R.I.; Hafner, A. Review on cold thermal energy storage applied to refrigeration systems using phase change materials. Therm. Sci. Eng. Prog. 2020, 22, 100807. [Google Scholar] [CrossRef]
  4. Wang, H.; Xie, B.; Li, C. Review on operation control of cold thermal energy storage in cooling systems. Energy Built Environ. 2024, in press. [Google Scholar] [CrossRef]
  5. Serale, G.; Baronetto, S.; Goia, F.; Perino, M. Characterization and Energy Performance of a Slurry PCM-based Solar Thermal Collector: A Numerical Analysis. Energy Procedia 2014, 48, 223–232. [Google Scholar] [CrossRef]
  6. Liu, Z.; Quan, Z.; Zhao, Y.; Zhang, W.; Yang, M.; Shi, J.; Bai, Z. Dynamic modelling and performance prediction of a novel direct-expansion ice thermal storage system based multichannel flat tube evaporator plus micro heat pipe arrays storage module. Renew. Energy 2023, 217, 119153. [Google Scholar] [CrossRef]
  7. Wang, X.; Qu, X.; Wang, C.; Zhu, B. Review on Phase Change Cool Storage in Air-conditioning System. Build. Sci. 2013, 29, 98–106. [Google Scholar] [CrossRef]
  8. Feng, X. Research on Operation Strategy and Application of Phase Change Cool Storage Air Conditioning System. Master’s Thesis, Beijing University of Civil Engineering and Architecture, Beijing, China, 2020. [Google Scholar] [CrossRef]
  9. Yang, J. Preparation and Performance Study of Phase Change Material with Hydrated Salt for Cold Storage in Air Conditioning. Master’s Thesis, Southeast University, Nanjing, China, 2022. [Google Scholar] [CrossRef]
  10. Riahi, A.; Shafii, M.B. Parametric study of a vapor compression refrigeration system integrated with a PCM storage tank for increasing condenser sub-cooled temperature. Case Stud. Therm. Eng. 2023, 47, 103100. [Google Scholar] [CrossRef]
  11. Ma, Y. Study on Application of Phase Change Microcapsule in Solar Composite Air Conditioning System. Master’s Thesis, Zhongyuan University of Technology, Zhengzhou, China, 2020. [Google Scholar] [CrossRef]
  12. Zhao, D.; Tan, G. Experimental evaluation of a prototype thermoelectric system integrated with PCM (phase change material) for space cooling. Energy 2014, 68, 658–666. [Google Scholar] [CrossRef]
  13. Abdolmaleki, L.; Berardi, U. Single and Multi-phase Change Materials Used in Cooling Systems. Int. J. Thermophys. 2022, 43, 61. [Google Scholar] [CrossRef]
  14. Peng, S.-H.; Lo, S.-L. Hybrid (Optimal) Selection Model for Phase Change Materials Used in the Cold Energy Storage of Air Conditioning Systems. Energies 2023, 17, 63. [Google Scholar] [CrossRef]
  15. Tang, R.; Gui, S.; Yan, J.; Li, D. Research Progress of Phase Change Materials Applied in Air-Conditioning Cold Storage. J. Build. Energy Effic. 2020, 48, 57–61. [Google Scholar] [CrossRef]
  16. Zhang, W.; Zhao, C. Examining the Performance of Portable Cold-storage Box Based on Phase-change Technology. J. Refrig. 2024, 45, 145–157. [Google Scholar] [CrossRef]
  17. Lin, N.; Li, C.; Zhang, D.; Li, Y.; Chen, J. Emerging phase change cold storage materials derived from sodium sulfate decahydrate. Energy 2022, 245, 123294. [Google Scholar] [CrossRef]
  18. Chen, Y.; Wang, D.; Yang, X.; Chen, G.; Zhang, Y.; Chen, B. Analysis of Thermal Characteristics of Eutectic Salt Phase Change Materials for Air Conditioning. In Proceedings of the 11th National Conference on Energy and Thermal Engineering NCETE, The Chinese Society for Metals, Maanshan City, China, 14–16 July 2021; pp. 292–296. [Google Scholar] [CrossRef]
  19. Liu, F.; Liu, X. Preparation and properties study of phase change materials for fruits and vegetables preservation. J. Hebei Univ. Sci. Technol. 2018, 39, 540–545. [Google Scholar] [CrossRef]
  20. Yang, J.; Yin, Y. Research Progress of Phase Change Materials for Cold Thermal Energy Storage in Air-conditioners. J. Refrig. 2022, 43, 37–44. [Google Scholar]
  21. Wang, Y.; Xing, M.; Jing, D.; Zhang, H.; Wang, R. Study on the Performance of CNT Based Phase Change Cold Storage Air Conditioning; China Academic Journal Electronic Publishing House: Ningbo, China, 2023; pp. 1032–1036. [Google Scholar] [CrossRef]
  22. Yan, W.-M.; Huang, C.-Y.; Gao, K.-E.; Amani, M.; Chien, L.-H.; Homayooni, A. Study on the performance enhancement of ice storage and melting processes in an ice-on-coil thermal energy storage system. J. Energy Storage 2023, 72, 108410. [Google Scholar] [CrossRef]
  23. Liu, K.; He, Z.; Lin, P.; Zhao, X.; Chen, Q.; Su, H.; Luo, Y.; Wu, H.; Sheng, X.; Chen, Y. Highly-efficient cold energy storage enabled by brine phase change material gels towards smart cold chain logistics. J. Energy Storage 2022, 52, 104828. [Google Scholar] [CrossRef]
  24. Li, M.; Chen, P.; Lv, Z.; Chen, Z. Preparation and Modification of Composite Inorganic Salt Phase Change Materials for Cold Storage. J. Refrig. 2021, 42, 106–115. [Google Scholar]
  25. Jiao, F.; Li, X.; Ma, Z.; Ma, K.; Li, J.; Lv, G.; Yu, Z. Review on Research Progress and Applications of Phase Change Materials for Cold Storage. J. Refrig. Technol. 2023, 46, 71–79. [Google Scholar] [CrossRef]
  26. Xie, Y.; Shi, B.; Feng, Y. Experimental Study on Thickening Characteristics of Eutectic Salt Cold Storage Material for Air Conditioning. J. Build. Energy Effic. 2020, 48, 9–13, 32. [Google Scholar]
  27. Liu, J.; Liu, R.; Wang, C.; Liang, Y. Thermodynamics test of Na2SO4·10H2O phase change compound system. Energy Conserv. 2007, 2007, 13–14. [Google Scholar]
  28. Peng, S.-H.; Lo, S.-L. An Economic Analysis of Energy Saving and Carbon Mitigation by the Use of Phase Change Materials for Cool Energy Storage for an Air Conditioning System—A Case Study. Energies 2024, 17, 912. [Google Scholar] [CrossRef]
  29. Yang, N.; Wang, J.; Liu, J.; Zhang, Z. Experimental Study on Eutectic Salt Air Conditioning Thermal Energy Storage Material with Added Nanoparticles. Build. Energy Effic. 2017, 45, 10–13, 18. [Google Scholar]
  30. Wei, Z.; Liu, X.; Liu, Z. Research on performance of phase change cold storage supermarket freezing cabinet. J. Appl. Sci. Technol. 2021, 2021, 59–63. [Google Scholar] [CrossRef]
  31. Lu, W.; Liu, G.; Xing, X.; Wang, H. Investigation on Ternary Salt-Water Solutions as Phase Change Materials for Cold Storage. Energy Procedia 2019, 158, 5020–5025. [Google Scholar] [CrossRef]
  32. Ban, C.; Lv, L.; Pan, L. Preparation and performance evaluation of freeze type composite phase change material. New Chem. Mater. 2019, 47, 218. [Google Scholar]
  33. Lv, Y. Organic Phase Change Cold Storage Material for Air Conditioning of Regular Working Condition Research. Master’s Thesis, TianJin University, Tianjin, China, 2017. [Google Scholar]
  34. Rodríguez, A.T.; Gálvez, D.M.; Kerdan, I.G.; Casarín, R.S. A Comparison of a Transparent Thermal Insulation System Filled with Refrigerants and a Pig-Fat Based PCM. Energies 2023, 16, 3630. [Google Scholar] [CrossRef]
  35. Chen, X.; Zhang, Q.; Zhai, Z.; Qiu, J. Performance of a cold storage air-cooled heat pump system with phase change materials for space cooling. Energy Build. 2020, 228, 110405. [Google Scholar] [CrossRef]
  36. Sarkar, S.; Mestry, S.; Mhaske, S.T. Developments in phase change material (PCM) doped energy efficient polyurethane (PU) foam for perishable food cold-storage applications: A review. J. Energy Storage 2022, 50, 104620. [Google Scholar] [CrossRef]
  37. Zhang, X.; Yang, Y. Preparation and cycling performance of lauric acid-caprylic acid as cool storage phase change material. Chem. Eng. J. 2013, 41, 10–13. [Google Scholar]
  38. Li, G.; Hwang, Y.; Radermacher, R. Review of cold storage materials for air conditioning application. Int. J. Refrig. 2012, 35, 2053–2077. [Google Scholar] [CrossRef]
  39. Tang, H.; Wu, W.; Miao, P.; Zhang, H. Theoretical prediction and experimental research of binary organic phase change storage materials used for air-conditioning system. New Chem. Mater. 2016, 44, 121–123, 126. [Google Scholar]
  40. Zuo, J.; Li, W.; Xu, S. Thermal Properties of Caprylic Acid and Lauric Acid as Phase Change Cool Storage Material. Acta Energiae Solaris Sin. 2012, 33, 131–134. [Google Scholar]
  41. Li, Y. Preparation and Performance Study of Organic Phase Change Coolant Used in Cold Chain. Master’s Thesis, Xi’an University of Technology, Xi’an, China, 2021. [Google Scholar] [CrossRef]
  42. Wan, X.; Chen, C.; Tian, S.; Guo, B. Thermal characterization of net-like and form-stable ML/SiO2 composite as novel PCM for cold energy storage. J. Energy Storage 2020, 28, 101276. [Google Scholar] [CrossRef]
  43. Wang, J.; Xie, H.; Xin, Z. Thermal properties of paraffin based composites containing multi-walled carbon nanotubes. Thermochim. Acta 2009, 488, 39–42. [Google Scholar] [CrossRef]
  44. Qi, X. Development of Phase-Changing Coolant and Its Application on Preservation of Fruit and Vegetables. Master’s Thesis, Zhejiang University, Hangzhou, China, 2015. [Google Scholar]
  45. Cabeza, L.F.; Mehling, H.; Hiebler, S.; Ziegler, F. Heat transfer enhancement in water when used as PCM in thermal energy storage. Appl. Therm. Eng. 2002, 22, 1141–1151. [Google Scholar] [CrossRef]
  46. Waqas, A.; Ji, J.; Ali, M.; Alvi, J.Z. Effectiveness of the phase change material-based thermal energy storage integrated with the conventional cooling systems of the buildings—A review. Proc. Inst. Mech. Eng. Part A J. Power Energy 2018, 232, 735–766. [Google Scholar] [CrossRef]
  47. Ma, Z.; Lin, W.; Sohel, M.I. Nano-enhanced phase change materials for improved building performance. Renew. Sustain. Energy Rev. 2016, 58, 1256–1268. [Google Scholar] [CrossRef]
  48. Cabeza, L.F.; Castell, A.; Barreneche, C.; De Gracia, A.; Fernández, A.I. Materials used as PCM in thermal energy storage in buildings: A review. Renew. Sustain. Energy Rev. 2011, 15, 1675–1695. [Google Scholar] [CrossRef]
  49. Alehosseini, E.; Jafari, S.M. Nanoencapsulation of phase change materials (PCMs) and their applications in various fields for energy storage and management. Adv. Colloid Interface Sci. 2020, 283, 102226. [Google Scholar] [CrossRef] [PubMed]
  50. Chang, Y.; Yao, X.; Chen, Y.; Huang, L.; Zou, D. Review on ceramic-based composite phase change materials: Preparation, characterization and application. Compos. Part B Eng. 2023, 254, 110584. [Google Scholar] [CrossRef]
  51. Mosaffa, A.H.; Talati, F.; Rosen, M.A.; Basirat-Tabrizi, H. Green’s function solution for transient heat conduction in annular fin during solidification of phase change material. Appl. Math. Mech.-Engl. Ed. 2012, 33, 1265–1274. [Google Scholar] [CrossRef]
  52. Fashandi, M.; Leung, S.N. Preparation and characterization of 100% bio-based polylactic acid/palmitic acid microcapsules for thermal energy storage. Mater. Renew. Sustain. Energy 2017, 6, 14. [Google Scholar] [CrossRef]
  53. Yang, Y.; Zhang, W.; Dong, Z.; Wang, H.; Pan, Y. Preparation and thermal performance of new composite phase change storage materials for refrigerator car. New Chem. Mater. 2013, 41, 41–43. [Google Scholar]
  54. Liu, Z.; Zhao, D.; Wang, Q.; Chi, Y.; Zhang, L. Performance study on air-cooled household refrigerator with cold storage phase change materials. Int. J. Refrig. 2017, 79, 130–142. [Google Scholar] [CrossRef]
  55. Jia, P.; Wu, W.; Wang, Y. Preparation of 0 °C phase change material and its cold storage performance in cold-chain logistics. Chem. Ind. Eng. Prog. 2019, 38, 2862–2869. [Google Scholar] [CrossRef]
  56. Kong, Q.; Mu, H.; Han, Y.; Wu, W.; Fang, X.; Liu, R.; Chen, H.; Gao, H. Preparation of Composite Phase Change Cold Storage Material and Its Effect on Storage Quality of Lentinula edodes. Food Sci. 2020, 41, 238–246. [Google Scholar]
  57. Wang, L.; Lu, W.; Xing, X. Investigation of New Low Temperature Composite Phase Change Materials for Cold Storage. Guangzhou Chem. 2021, 46, 50–56. [Google Scholar] [CrossRef]
  58. Wang, M.; Lei, M.; Wei, Y.; Yin, P. Study on composite phase change cold storage material for refrigerator freezer. Heilongjiang Sci. 2018, 9, 22–23. [Google Scholar]
  59. Li, J.; Xie, R.; Liu, G.; Foster, A. Development of New Low-temperature Phase Change Material and Equipment Used in Refrigerated Transportation. J. Refrig. 2018, 39, 32–37. [Google Scholar]
  60. Said, M.A.; Hassan, H. Impact of energy storage of new hybrid system of phase change materials combined with air-conditioner on its heating and cooling performance. J. Energy Storage 2021, 36, 102400. [Google Scholar] [CrossRef]
  61. Singh, P.C.; Halder, P. Performance Assessment of an Air-Conditioning System Utilizing a PCM-Based Annulus Cylindrical Latent Heat Storage. Arab. J. Sci. Eng. 2023, 49, 1759–1770. [Google Scholar] [CrossRef]
  62. Gao, X. Study on Cool Storage and Discharging Characteristic of Direct-contact Cool Storage Device at Conventional Air-Conditioning. Master’s Thesis, Harbin University of Commerce, Harbin, China, 2014. [Google Scholar]
  63. Zeng, X.; Wang, H.; Han, B. Performance test on cooling process of phase change cool storage device for air conditioning of rail vehicle. New Chem. Mater. 2020, 48, 230–233+238. [Google Scholar] [CrossRef]
  64. Wang, S.; Wang, H.; Sun, H.; Zeng, X. Numerical simulation on cooling process of phase change cool storage device for rail vehicle air conditioning. New Chem. Mater. 2020, 48, 152–156. [Google Scholar] [CrossRef]
  65. Jia, J.; Lee, W.L. Experimental investigations on using phase change material for performance improvement of storage-enhanced heat recovery room air-conditioner. Energy 2015, 93, 1394–1403. [Google Scholar] [CrossRef]
  66. Zhao, D.; Tan, G. Numerical analysis of a shell-and-tube latent heat storage unit with fins for air-conditioning application. Appl. Energy 2015, 138, 381–392. [Google Scholar] [CrossRef]
  67. Wan, Z.; Su, C.; Li, X.; Cheng, L.; Lu, Y. Feasibility Study on a New Cooling Storage System of Phase Change with Condensate in Air Conditioning. J. Green Sci. Technol. 2019, 195–197. [Google Scholar] [CrossRef]
  68. Nguyen, X.V. Fabrication and Performance Evaluation of Cold Thermal Energy Storage Tanks Operating in Water Chiller Air Conditioning System. Energies 2021, 14, 4159. [Google Scholar] [CrossRef]
  69. Loem, S.; Asanakham, A.; Deethayat, T.; Vorayos, N.; Kiatsiriroat, T. Testing of solar inverter air conditioner with PCM cool storage and sizing of photovoltaic modules. Therm. Sci. Eng. Prog. 2023, 38, 101671. [Google Scholar] [CrossRef]
  70. Loem, S.; Deethayat, T.; Asanakham, A.; Kiatsiriroat, T. Study on phase change material thermal characteristics during air charging/discharging for energy saving of air-conditioner. Heat Mass Transf. 2020, 56, 2121–2133. [Google Scholar] [CrossRef]
  71. Chaiyat, N. Energy and economic analysis of a building air-conditioner with a phase change material (PCM). Energy Convers. Manag. 2015, 94, 150–158. [Google Scholar] [CrossRef]
  72. Wonorahardjo, S.; Sutjahja, I.M.; Tunçbilek, E.; Achsani, R.A.; Arıcı, M.; Rahmah, N. PCM-based passive air conditioner in urban houses for the tropical climates: An experimental analysis on the stratum air circulation. Build. Environ. 2021, 192, 107632. [Google Scholar] [CrossRef]
  73. Wu, D.; Zhang, Q.; Chen, X.; Liao, S.; Sha, Z. Experimental Study on the Performance of Small-sized Cool Storage Air Conditioning with Phase Change Materials. Build. Sci. 2017, 33, 62–67. [Google Scholar] [CrossRef]
  74. Zhou, G.; Yang, Y.; Xu, H. Energy performance of a hybrid space-cooling system in an office building using SSPCM thermal storage and night ventilation. Sol. Energy 2011, 85, 477–485. [Google Scholar] [CrossRef]
  75. Nie, B.; Du, Z.; Chen, J.; Zou, B.; Ding, Y. Performance enhancement of cold energy storage using phase change materials with fumed silica for air-conditioning applications. Int. J. Energy Res. 2021, 45, 16565–16575. [Google Scholar] [CrossRef]
  76. Goyal, A.; Kozubal, E.; Woods, J.; Nofal, M.; Al-Hallaj, S. Design and performance evaluation of a dual-circuit thermal energy storage module for air conditioners. Appl. Energy 2021, 292, 116843. [Google Scholar] [CrossRef]
  77. Chen, X.; Zhang, Q.; Zhai, Z.J.; Ma, X. Potential of ventilation systems with thermal energy storage using PCMs applied to air conditioned buildings. Renew. Energy 2019, 138, 39–53. [Google Scholar] [CrossRef]
  78. Marani, A.; Nehdi, M.L. Integrating phase change materials in construction materials: Critical review. Constr. Build. Mater. 2019, 217, 36–49. [Google Scholar] [CrossRef]
  79. Almeshaal, M.A.; Sakr, R.Y. Numerical study of encapsulated nanoparticles enhanced phase change material in thermal energy cool storage packed bed system. J. Energy Storage 2023, 68, 107837. [Google Scholar] [CrossRef]
  80. Ismail, M.; Zahra, W.K.; Hassan, H. Numerical investigation of the air conditioning system performance assisted with energy storage of capsulated concave/convex phase change material. J. Energy Storage 2023, 68, 107651. [Google Scholar] [CrossRef]
  81. Parameshwaran, R.; Kalaiselvam, S. Energy conservative air conditioning system using silver nano-based PCM thermal storage for modern buildings. Energy Build. 2014, 69, 202–212. [Google Scholar] [CrossRef]
  82. Deng, S.; Nie, C.; Jiang, H.; Ye, W.-B. Evaluation and optimization of thermal performance for a finned double tube latent heat thermal energy storage. Int. J. Heat Mass Transf. 2019, 130, 532–544. [Google Scholar] [CrossRef]
  83. Jamekhorshid, A.; Sadrameli, S.M.; Farid, M. A review of microencapsulation methods of phase change materials (PCMs) as a thermal energy storage (TES) medium. Renew. Sustain. Energy Rev. 2014, 31, 531–542. [Google Scholar] [CrossRef]
  84. Memon, S.A. Phase change materials integrated in building walls: A state of the art review. Renew. Sustain. Energy Rev. 2014, 31, 870–906. [Google Scholar] [CrossRef]
  85. Li, X.-Y.; Li, L.; Yu, J.-W.; Liu, J.-Q.; Wu, Y.-Y. Investigation of the dynamic characteristics of a storage tank discharging process for use in conventional air-conditioning system. Sol. Energy 2013, 96, 300–310. [Google Scholar] [CrossRef]
  86. Li, S.; Peng, J.; Li, H.; Zou, B.; Song, J.; Ma, T.; Ji, J. Zero energy potential of PV direct-driven air conditioners coupled with phase change materials and load flexibility. Renew. Energy 2022, 200, 419–432. [Google Scholar] [CrossRef]
  87. Li, S.; Peng, J.; Zou, B.; Li, B.; Lu, C.; Cao, J.; Luo, Y.; Ma, T. Zero energy potential of photovoltaic direct-driven air conditioners with considering the load flexibility of air conditioners. Appl. Energy 2021, 304, 117821. [Google Scholar] [CrossRef]
  88. Qi, L.; Pan, H.; Zhu, X.; Zhang, X.; Salman, W.; Zhang, Z.; Li, L.; Zhu, M.; Yuan, Y.; Xiang, B. A portable solar-powered air-cooling system based on phase-change materials for a vehicle cabin. Energy Convers. Manag. 2017, 150, 148–158. [Google Scholar] [CrossRef]
  89. Sun, B. The Numerical Simulation of Radiant Floor Cooling and Heating System with Double Phase Change Energy Storage and the Thermal Performance. Master’s Thesis, Northeast Petroleum University, Daqing, Chinna, 2022. [Google Scholar] [CrossRef]
  90. Zheng, L.; Zhang, W.; Xie, L.; Wang, W.; Tian, H.; Chen, M. Experimental study on the thermal performance of solar air conditioning system with MEPCM cooling storage. Int. J. Low-Carbon Technol. 2019, 14, 83–88. [Google Scholar] [CrossRef]
  91. Ahmed, H.A.; Megahed, T.F.; Nada, S.; Mori, S.; Hassan, H. Impact of modules number of thermoelectric cooler coupled with PV panels and phase change material on building air conditioning. J. Build. Eng. 2024, 86, 108914. [Google Scholar] [CrossRef]
  92. Maiorino, A.; Petruzziello, F.; Aprea, C. Refrigerated Transport: State of the Art, Technical Issues, Innovations and Challenges for Sustainability. Energies 2021, 14, 7237. [Google Scholar] [CrossRef]
  93. Shafiei, S.E.; Alleyne, A. Model predictive control of hybrid thermal energy systems in transport refrigeration. Appl. Therm. Eng. 2015, 82, 264–280. [Google Scholar] [CrossRef]
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Figure 1. Peak shaving and valley filling schematic diagram.
Figure 1. Peak shaving and valley filling schematic diagram.
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Figure 2. Categorization of phase change materials.
Figure 2. Categorization of phase change materials.
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Figure 5. The latent heat of phase transition of typical composite phase change materials (kJ/kg) [38,51,52,53,54,55,56,57,58,59]. (The different color represents the highest latent heat).
Figure 5. The latent heat of phase transition of typical composite phase change materials (kJ/kg) [38,51,52,53,54,55,56,57,58,59]. (The different color represents the highest latent heat).
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Figure 6. (a) Physical model of phase change storage system, which is composed of one of PCM10HC plates and one of PCM24E plates; (b) real experiment, adapted from [60]. (3: a centrifugal fan, 6: a variable direct current power supply with an uncertainty of ±0.025% for the output volts and current, 7: a 2.7 m long wooden channel, 8 and 9: data acquisition center with an uncertainty of ±0.01 °C/°C.).
Figure 6. (a) Physical model of phase change storage system, which is composed of one of PCM10HC plates and one of PCM24E plates; (b) real experiment, adapted from [60]. (3: a centrifugal fan, 6: a variable direct current power supply with an uncertainty of ±0.025% for the output volts and current, 7: a 2.7 m long wooden channel, 8 and 9: data acquisition center with an uncertainty of ±0.01 °C/°C.).
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Figure 7. Series form of the cold storage system: (a) upstream of the host, (b) downstream of the host, (c) parallel form of the cold storage system; adapted from [8].
Figure 7. Series form of the cold storage system: (a) upstream of the host, (b) downstream of the host, (c) parallel form of the cold storage system; adapted from [8].
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Figure 8. Schematic and photograph of the prototype, adapted from [65].
Figure 8. Schematic and photograph of the prototype, adapted from [65].
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Figure 9. (a) Conceived schematic diagram of an air conditioner integrated with PCM thermal storage; (b) schematic diagram and cross-section of a PCM thermal storage unit; (c) photograph of a PCM thermal storage unit during heat charging process, adapted from [66].
Figure 9. (a) Conceived schematic diagram of an air conditioner integrated with PCM thermal storage; (b) schematic diagram and cross-section of a PCM thermal storage unit; (c) photograph of a PCM thermal storage unit during heat charging process, adapted from [66].
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Figure 10. (a) Principle of condensate phase change storage system [67]; (b) photograph of the thermal storage tank integrated into the system, adapted from [68].
Figure 10. (a) Principle of condensate phase change storage system [67]; (b) photograph of the thermal storage tank integrated into the system, adapted from [68].
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Figure 11. (a) Prototype of an air conditioner integrating with a PCM bed; (b) schematic of the testing room; (c) installing the PCM bed in the return duct, adapted from [71].
Figure 11. (a) Prototype of an air conditioner integrating with a PCM bed; (b) schematic of the testing room; (c) installing the PCM bed in the return duct, adapted from [71].
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Figure 12. PCM storage panel with placed 80 cylindrical plastic containers, adapted from [72].
Figure 12. PCM storage panel with placed 80 cylindrical plastic containers, adapted from [72].
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Figure 13. (a) TES−integrated air conditioner using compressed, expanded natural graphite with n-tetradecane; (b) schematic diagram of an experiment; (c) module CAD rendering (left) and the prototype (right), adapted from [76].
Figure 13. (a) TES−integrated air conditioner using compressed, expanded natural graphite with n-tetradecane; (b) schematic diagram of an experiment; (c) module CAD rendering (left) and the prototype (right), adapted from [76].
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Figure 14. Proposed air–PCM HX connected with a simple AC unit, adapted from [80].
Figure 14. Proposed air–PCM HX connected with a simple AC unit, adapted from [80].
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Figure 15. PVACs coupled with PCMs and load flexibility, adapted from [86].
Figure 15. PVACs coupled with PCMs and load flexibility, adapted from [86].
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Figure 16. Schematic diagram of the experimental unit with charging and discharging of the PCM packed bed cool storage, adapted from [69].
Figure 16. Schematic diagram of the experimental unit with charging and discharging of the PCM packed bed cool storage, adapted from [69].
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Figure 17. (a) Architecture of a solar-powered PCM-based cooling system; (b) schematic of the proposed solar-powered cooling system based on PCMs for vehicle cabin; (c) installation of the solar-powered PCM-based air cooling system for vehicle cabin, adapted from [88].
Figure 17. (a) Architecture of a solar-powered PCM-based cooling system; (b) schematic of the proposed solar-powered cooling system based on PCMs for vehicle cabin; (c) installation of the solar-powered PCM-based air cooling system for vehicle cabin, adapted from [88].
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Figure 18. A solar-powered air conditioning system with PCM cooling storage rig and the test instruments of the solar-powered air conditioning system, adapted from [90].
Figure 18. A solar-powered air conditioning system with PCM cooling storage rig and the test instruments of the solar-powered air conditioning system, adapted from [90].
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Figure 19. Model and wall construction, adapted from [91].
Figure 19. Model and wall construction, adapted from [91].
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Table 3. Some typical PCMs used in organic phase change cold storage and their physical properties parameters; data from [13,25].
Table 3. Some typical PCMs used in organic phase change cold storage and their physical properties parameters; data from [13,25].
PCMPhase Change Temperature (°C)Latent Heat (kJ/kg)Thermal Conductivity W/(m·K)ApplicationReferencesCosts
Paraffin RT11HC10~12 0.2Air-cooled heat pump system[35]161
Polyethylene Glycol E-40899.60.18 (L)Food cold storage[36]104
Lauric acid, capric acid
with a mass ratio of 21:79		7.73134 Air conditioning[37]435
S7, S8, S107–10150–155 Air conditioning[38]
OA/nutmeg alcohol
with a mass ratio of 73.7:26.3		6.9169.1 Air conditioning[39]782
OA,LA6.2136.43 [40]540
Lauric acid/tetradecane with a molar ratio of 21:795.51209.42 Cold chain[41]508
Methyl laurate5.48224 [42]633
Tetrahydrofuran5280 [43]914
Decanoic acid/decanol with a molar ratio of 36:643.8180.94 Cold chain[41]504
Decanoic acid/methyl laurate with a molar ratio of 30:701.62193.4 Cold chain[41]575
Mannitol aqueous solution−3~−3.5276.2 Preservation of fruit and vegetables [44]455
Teg−7247 [45]123
Paraffin RT-9HC−9~10202Liquid 0.174
Solid 0.309		Refrigeration systems[3]419
Table 4. Some typical PCMs used in organic phase change cold storage and their physical properties parameters [13,25].
Table 4. Some typical PCMs used in organic phase change cold storage and their physical properties parameters [13,25].
PCMPhase Change Temperature (°C)Latent Heat (kJ/kg)ApplicationReferencesCosts
CaCl2, H2O29.7187.4 [51]96
Na2B4O7·10H2O, NH4Br9.5–10179Bio-based polymeric shell[52]345
Na2SO4, H2O, NaCl, NH4Cl7.5121Air conditioning[38]255
Decanoic acid, tetradecane, and graphite with a mass fraction of 74%, 26%, and 6% 6.6145.3Refrigerator car[53]532
Deionized water (softened water) with 1% superabsorbent polymer (SAP) and 0.03% diatomaceous earth added0.41332.7Air-cooled household refrigerator[54]
A 5% sorbitol aqueous solution with 0.40% TiO2 and 1.0% sodium polyacrylate−2.9293.8Cold-chain logistics[55]782
Sodium benzoate, water, and 0.1% diatomaceous earth−4.06316.632Fruits and vegetables preservation[19]149
A mixture with a mass fraction of 2% potassium chloride, 1.37% glycine, and 3.37% SAP−6.08318.14Storage Quality of Lentinula edodes[56]
Propanetriol: ammonium chloride: water = 1:2:7−17.6197.7 [57]700
An 18% sodium chloride solution with 5% SAP and 0.03% diatomaceous earth −18.98120.6Air-cooled household refrigerator[54]
Propanetriol, sodium chloride, and water with a mass ratio of 15%, 10%, 75%−21.4125.3Freezer refrigerator[58]609
A mixture of 20% sodium chloride solution and 50% propanetriol solution with a mass ratio of 2.5:7.5−31.5175.3Refrigerated transportation[59]590
Table 5. Comparison between ceramic-based composite phase change materials and three other phase change materials [50].
Table 5. Comparison between ceramic-based composite phase change materials and three other phase change materials [50].
MatrixAdvantagesDisadvantages
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Ceramic matrix		1. High sensible heat storage capacityFrangibility
2. Good dimensional stability
3. High wettable with PCMs
4. Excellent chemical and thermal stability
5. High corrosion resistance
6. Low cost
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Carbon matrix		Excellent thermal conductivity1. High cost
2. Poor high-temperature thermal stability
3. Complexity of preparation
Metallic matrix1. Excellent thermal conductivity1. High cost
2. Good mechanical strength2. Corrosion issue
3. High porosity3. Insufficient wetting to PCMs
4. Excellent thermal stability
Table 6. Parameters and data for cost–benefit analysis of AC systems; unit: CHF [28].
Table 6. Parameters and data for cost–benefit analysis of AC systems; unit: CHF [28].
AC SystemsParametersDescription012310Present Value (CHF)
Without phase change material storage KInvestment cost507,021.76 507,021.76
C1Operation costs60,136.6960,136.6960,136.6960,136.6960,136.69368,820.14
C2Maintenance costs25,374.0425,374.0425,374.0425,374.0425,374.04153,354.23
B1Electricity bill 45,675.08
B2Savings 17,600.63
DSalvage value 45,337.71652,469
With phase change material storageKInvestment cost441,000.66 441,000.66
C1Operation costs52,723.2952,723.2952,723.2952,723.2952,723.29305,275.74
C2Maintenance costs39,843.5339,843.5339,843.5339,843.5339,843.53261,305.83
B1Electricity bill 2,000,000.00
B2Savings325,471.13325,471.13325,471.13325,471.13325,471.1315,000.00
DSalvage value 39,469.1715,217.07
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Li, Z.; Sha, Y.; Zhang, X. Research on Phase Change Cold Storage Materials and Innovative Applications in Air Conditioning Systems. Energies 2024, 17, 4365. https://doi.org/10.3390/en17174365

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Li Z, Sha Y, Zhang X. Research on Phase Change Cold Storage Materials and Innovative Applications in Air Conditioning Systems. Energies. 2024; 17(17):4365. https://doi.org/10.3390/en17174365

Chicago/Turabian Style

Li, Zhengjing, Yishun Sha, and Xuelai Zhang. 2024. "Research on Phase Change Cold Storage Materials and Innovative Applications in Air Conditioning Systems" Energies 17, no. 17: 4365. https://doi.org/10.3390/en17174365

APA Style

Li, Z., Sha, Y., & Zhang, X. (2024). Research on Phase Change Cold Storage Materials and Innovative Applications in Air Conditioning Systems. Energies, 17(17), 4365. https://doi.org/10.3390/en17174365

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