Search Results (14)

A flat-plate unglazed solar water heater (SWH) with a polymer thermal absorber was developed and experimented with. Polymer thermal absorbers could be a viable alternative to metal thermal absorbers for SWH systems. The performance of this polymer SWH system was measured based on inlet and outlet water temperature, water flow rate, ambient air temperature and solar irradiance. The polymer thermal absorbers were hollow Polyvinyl Chloride (PVC) tubes with a 20 mm external diameter and 3 mm thickness and were painted black to enhance radiation absorption. The pipes are arranged in a rectangular spiral inward–outward alternating-flow (RSioaf) pattern. The collector pipes were placed in a 1 m × 1 m enclosure with bottom insulation and a reflective surface for maximized radiation absorption. Water circulated through a closed loop with an uninsulated 16 L storage tank, driven by a pump and controlled by two valves to maintain a mass flow rate of 0.0031 to 0.0034 kg·s⁻¹. The test was conducted under a partially clouded sky from 9 a.m. to 5 p.m., with solar irradiance between 105 and 1003 W·m⁻² and an ambient air temperature of 27–36 °C. This SWH system produced outlet hot water at 65 °C by midday and maintained the storage temperature at 63 °C until the end of the test period. Photothermal energy conversion was recorded, showing a maximum value of 23%. Results indicate that a flat-plate solar water heater with a polymer thermal absorber in an RSioaf design can be an effective alternative to an SWH with a metal thermal absorber. Its performance can be improved with glazing and optimized tube sizing. Full article

Solar energy is one of the most promising forms of alternative energy because it has no adverse effects on the environment and is entirely free. Converting solar energy into thermal energy is the most common and straightforward method; the efficiency of solar thermal conversion is approximately 70 percent. The intermittent nature of solar energy availability affects the performance of solar water heaters (SWH), which lowers the usefulness of solar energy in residential and commercial settings, particularly for water heating. Even at low temperatures, the performance of a collector can be improved by using low-density polyethylene (LDPE) glazing instead of traditional glass because it is less expensive and lighter than glass. Using a comprehensive experimental-simulative study, the Glass Solar water heater (glass SWH) and the low-density polyethylene solar water heater (LDPE SWH) are analyzed, examined, and compared in this work. These solar water heaters have galvanized iron (GI) as their absorber material. The SWHs were operated in a closed loop at a constant mass flow rate of 0.013 kg/s, and a 4E analysis (which stands for energy, exergy, economics, and efficiency recovery ratio) was carried out. This analysis included a look at the dynamic time, uncertainty, weight reduction, carbon footprint, and series connection. An LDPE SWH has an energy efficiency that is 5.57% and an exergy efficiency that is 3.2% higher than a glass SWH. The weight of the LDPE SWH is 32.56% lower than that of the glass SWH. Compared to the price of a conventional geyser, installing our SWH results in a cost savings of 40.9%, and monthly energy costs are reduced by an average of 25.5%. Compared to October, September has the quickest dynamic time to reach the desired temperature, while October has the most significant dynamic time. The efficiency recovery ratio (ERR) of a glass SWH is 0.0239% lower than that of an LDPE SWH. LDPE SWHs had a carbon credit worth INR 294.44 more than glass SWHs. The findings of these tests demonstrate that the LDPE SWH is a practical replacement for traditional means of heating water, such as SWHs and geysers. Full article

The solar water heater can be integrated into future residential buildings as the main energy source, which will subsequently reduce the energy cost of water heating. An original configuration for an efficient Domestic Hot Water (DHW) storage tank is developed and experimentally evaluated under Saharan climate. This novel DHW configuration includes a hybrid (solar and electric) energy system with a flat plate solar collector coupled with an electric heater. Additionally, a phase change material (PCM) mixture that is composed of paraffin wax and animal fat with a melting temperature between 35.58 °C and 62.58 °C and latent heat between 180 and 210 kJ/kg is integrated into this novel tank configuration. The experimental results indicated that hot water production by using latent heat storage could be economically attractive. By evaluating the cost of water heating expressed in Algerian dinar per liter (DZD/L), it was found that one liter of hot water may cost around 0.1362 DZD/L (i.e., 0.00096 USD/L) compared to 0.4431 DZD/L for the conventional water heater, an average energy cost savings of 69.26%. On a yearly basis, the average energy cost savings may reach up to 80.25% if optimal tilt for the solar collector is adopted on a monthly basis. The flat plate collector may be vulnerable to convective heat transfer; therefore, other solar collectors, such as vacuum tube collectors, may provide enhanced energy performance. Full article

Energy consumption in India is massive, and even the quantity used for household tasks is substantial. The majority of the requirement is satisfied by using fossil fuels, which are the traditional methods. Heating water is the most frequent home application. Accordingly, this article examines studies from the previous ten years. The information in this article demonstrates that using renewable energy is the greatest way to cut back on both the use of fossil fuels and carbon emissions while heating water for residential use. Solar, hydroelectric, wind, and biofuels are the most significant renewable sources for improving building efficiency that can be used for an extended period of time. The solar water heater is a common example of how solar energy is being used in homes more frequently. In order to identify key issues and solutions related to employing solar water heaters as an effective water heating application in both commercial and residential buildings, this article compiles research data from earlier studies (2012–2022). The literature survey was carried out using Scopus, a specialized database. Sixty-six dedicated research publications having search keywords plus recently published articles that matched the inclusion criteria were chosen for this review study. The study’s findings show that there is a greater inclination of researchers towards research and development in the field of domestic solar water heaters. The research publications that are being presented are all from the past 10 years (2012–2022) and stress the use of solar energy in increasing building efficiency. The study highlights how flat plate solar collectors with distilled water as the heat transfer fluid and a phase-changing substance as the thermal energy storage could potentially be enhanced. The thermal conductivity of paraffin wax and distilled water was improved by 75% of the researchers by using 0.05 to 0.5% concentrations of Al and Cu oxide nanoparticles, making it useful in solar water heaters. A total of 78% of researchers are interested in domestic water heating applications since they use a lot of energy in both urban and rural settings. Full article

The manuscript is written for flow escalation based on an experimental data for a Solar Assisted Heat Pump Water Heater (SAHPWH) increasing building energy efficiency. For the investigation, a Solar Assisted Heat Pump (SAHP) was conceived, manufactured, and tested in real time. The findings of the experiments shows that single glazing with average sun radiation of 600–750 W/m², COP of approx. 6 can be obtained with identical heat gains. This study shows that when a flat plate collector of area 1.83 m (L) × 1.22 m (W) × 0.1 m (T) with a 0.5-mm-thick black copper plate absorber with clear glazing as a cover receives average radiation of 700 W/m², then setup can supply 60 litres of water for residential use from 15 °C to 45 °C in approx. 70 min. In addition, the study finds that the collector efficiency factor F’ is likewise shown to have a direct connection with the absorber and an inverse relationship of tube spacing. The findings indicated that the technology has significant commercial potential, particularly in sectors such as with solar resources for improving building energy efficiency. Full article

A humidification–dehumidification (HDH) desalination system requires thermal energy to desalt seawater. An environmentally friendly approach to obtain thermal energy is to utilize solar energy using solar collectors. Either seawater or air (or both) are typically preheated by HDH desalination systems before these fluids are conveyed to the humidifier column. Compared with preheating only air or water, preheating both is preferred because improved performance and higher productivity are achieved. Many researchers have proposed dual preheated HDH systems utilizing two separate solar heaters/collectors for simultaneous air–seawater preheating. In this study, dual-fluid preheating is achieved using a single solar collector. The proposed simultaneous air–water solar heater (SAWSH) is a modified flat-plate collector designed for simultaneously preheating air and seawater before the fluids reach the humidifier. A thermodynamic study was conducted using formulated mathematical models based on energy and mass conservation principles. Then, the dual-fluid heating HDH system is compared with HDH systems in which only air or only water is heated. This work found that the former outperformed the latter. The daily and monthly performance levels of the system in terms of the outlet temperatures of air and water, distillate rate, and gain output ratio were calculated using the weather data of the hot and humid climate of Jeddah City, Saudi Arabia. Full article

South Africa is the most technologically advanced nation in Africa. However, the country is plagued with constant load shedding. The country receives about 2500 sunshine hours annually, with daily average irradiation levels of 4.5–6.5 kWh/m². Despite these potentials, the use of electricity for domestic water heating is still prevalent in the country. The mass rollout of solar water heating (SWH) technologies in the low-cost housing sector across the country were met with massive failures. This study aims to assess the energy yield of a passive flat plate and an evacuated tube solar water heating system by evaluating the performance of these systems to address the energy crisis in South Africa. The flat plate (FP) and evacuated tube (ET) solar water heating systems were monitored for four days, characterised by varying sky conditions through instantaneous data measurement at 5 s. The parameters measured were water temperature, ambient temperature, irradiance at the plane of array, relative humidity, wind speed and direction. The results obtained show that a maximum irradiance of 1050 W/m² was obtained on a clear day and corresponded to a hot water temperature of about 58 °C and 65 °C for the FP and ET, respectively. However, a cloudy day with a maximum irradiance of 400 W/m² produced about 22 °C and 29 °C of hot water for the FP and ET, respectively. The results obtained in this study will guide stakeholders in the renewable energy sector towards employing SWH systems to replace or augment the electric geyser. Solar water heaters (SWH) can be used in the low-cost housing sector to provide hot water. Hence, the assessments in this study offer essential information for the deployment of these systems to reduce demand on the ailing South African electricity utility, Eskom, and mitigate climate change. Full article

The need for hot water in residential buildings requires a significant energy potential. Therefore, an efficient water heating system is important to achieve the goal of saving high-grade energy. The most simple and cheapest solar water heater is a flat plate solar collector (FPSC), which can increase the thermal energy of fluid by absorbing solar radiation. The performance of FPSC is comparatively low due to the dilute nature of solar insolation. Therefore, advancement of FPSC is being undertaken to improve the performance and achieve size reduction. In past, several techniques have been exploited to improve the performance of FPSC, which are presented in the present paper. These techniques include surface modifications, use of nanofluids, solar selective coating, and applications of a mini/macro channel, heat pipe, and vacuum around absorber. Surface modification on the absorber/absorber tube techniques are exploited to transfer the maximum possible solar energy to working fluids by increasing the heat transfer rate. Insertion of wire mesh, coil, and twisted tapes in the flow has great potential to increase the Nusselt number by 460% at the expense of a large pressure drop. Selective coating of Cu0.44 Ti0.44 Mn0.84 helps to absorb up to 97.4% of the incident solar energy, which is more significant. Many nanofluids have been exploited as heat transfer fluids, as they not only increase the performance but also reduce the fluid inventory. So, these techniques play a very prominent role in the performance of FPSC, which are discussed in detail. Summaries of the results are presented and recommendations proposed. Full article

With the increase in oil prices, developing nations end up paying expensive electricity and heating bill. This leading study investigates the experimental development of a new energy-saving system by integrating a solar water heater and solar cooling absorption cycle with a conventional boiler for domestic hot water and heating purposes. The heating and cooling load calculations for space heating of the building were calculated using TRNSYS 14.1 computer software and the results were used in calculating the energy-saving value. A 65 flat plate solar collector-chiller system with a total surface area of 130 m² was integrated with the boiler and used to supply heating and cooling for a three-story building (1500 m²) in Al Bayt University, Jordan. The integrated system helped to save energy, reduced the emission of CO₂ into the atmosphere, supplied hot water, and space heating/cooling requirements to the building year-round, and reduced the overall energy cost of heating and cooling by 55% and 48%, respectively. Moreover, the techno-economic analysis showed that the payback period of the combined system with a total cost of $18,650 is roughly 2.5-year. The solar water heating/cooling system has the potential to provide more than 50% of the house energy demand free of charge with a significant reduction in carbon footprint. Full article

Various studies to improve the thermal performance of flat plate solar collector (FPSC) solar water heater have been conducted, and more are currently in progress. This study aims to review existing methods on thermal performance enhancement for FPSC and discuss on heat-transfer enhancement using vibration and its potential application for FPSC. Ten methods for improving thermal performance are identified, which include applications of nanofluids, absorber coatings, phase change materials (PCM), thermal performance enhancers, FPSC design modifications, polymer materials, heat loss reduction, mini and micro channel and heat-transfer enhancement using vibration. An examination of heat-transfer enhancement using vibration in low frequency ranges for an evacuated-tube solar collector (ETSC) solar water heater system showed that it can potentially achieve heat-transfer enhancement of up to 78%. Nevertheless, there is still a lack of research on the applications of heat-transfer enhancement using vibration on FPSC to date. Full article

High-rise buildings have a significant impact on the surrounding environment. Building-integrated solar water heating (SWH) systems are effective ways to use renewable energy in buildings. Impediments, such as security concerns, aesthetics and functionality, make it difficult to apply SWH systems in high-rise buildings. At present, only China uses SWH systems on a large scale in such buildings. What are China’s experiences and lessons learned in applying SWH systems in high-rises? Are these experiences scalable to other countries? This study used a combination of field investigation, literature review and case study to summarize 36 systems that had been in operation for 1–14 years. System types, collector types, installation methods, types of auxiliary heat sources, economic performance and various basic principles were summarized. The economic performance of SWH systems in high-rise buildings was analyzed and verified by a case study in Shanghai. The results show that the installation of SWH systems in high-rise buildings is feasible and reliable. Individual household systems (61%) were more popular than centralized systems (25%) and hybrid systems account (14%). The average area of solar collectors per household was 2.17 m²/household, the average design solar fraction was 52%. Flat plate solar collectors (53%) was the most commonly used collector, while electric heating elements (89%) were the most common auxiliary heat sources for SWH systems, followed by gas water heaters and air source heat pumps. The cost of SWH systems per m² of a building area was between 22 CNY/m² to 75 CNY/m². China’s unique practical experience gives a reference for other countries in their efforts to make high-rise buildings more sustainable. Full article

This article investigates the introduction of hybrid power plants for thermal energy production for the indoor space heating loads coverage. The plant consists of flat plate solar collectors with selective coating, water tanks as thermal energy storage and a biomass heater. A new operation algorithm is applied, maximizing the exploitation of the available thermal energy storage capacity and, eventually, the thermal power production from the solar collectors. An automation system is also designed and proposed for the realization of the newly introduced algorithm. The solar-combi system is computationally simulated, using annual time series of average hourly steps. A dimensioning optimization process is proposed, using as criterion the minimization of the thermal energy production levelized cost. The overall approach is validated on a school building with 1000 m² of covered area, located in the hinterland of the island of Crete. It is seen that, given the high available solar radiation in the specific area, the proposed solar-combi system can guarantee the 100% annual heating load coverage of the examined building, with an annual contribution from the solar collectors higher than 45%. The annually average thermal power production levelized cost is calculated at 0.15 €/kWh_th. Full article

The performance of a solar hot water system is assessed for heat pump and domestic heating applications. Thermodynamic analysis on a serpentine-type thermosyphon flat-plate solar heater is conducted using the Second Law of thermodynamics. Exergetic optimization is first performed to determine the parameters for the maximum exergy efficiency using MATLAB optimization toolbox. Geometric parameters (collector surface area, dimensions, and pipe diameter), optical parameters (transmittance absorptance product), ambient temperature, solar irradiation and operating parameters (mass flow rate, fluid temperature, and overall heat transfer (loss) coefficient) are accounted for in the optimization scheme. The exergy efficiency at optimum condition is found to be 3.72%. The results are validated using experimental data and found to be in good agreement. The analysis is further extended to the influence of various operating parameters on the exergetic efficiency. It is observed that optical and thermal exergy losses contribute almost 20%, whereas approximately 77% exergy destruction is contributed by the thermal energy conversion. Exergy destruction due to pressure drop is found negligible. The result of this analysis can be used for designing and optimization of domestic heat pump system and hot water application. Full article

Solar water heaters represent the success story in the development of renewable energy in Taiwan. With increasing public awareness, there are over 0.3 million residential systems in operation. To disseminate solar water heaters in remote islands, economic feasibility and water quality are taken into account in this study. The payback period in Kinmen and Penghu Counties are evaluated, according to effective annual solar energy gain, hot water consumption pattern and cost. Assessment of the scaling and corrosion tendencies for solar water heaters using tap and underground water are also presented. For flat-plate solar collectors with metal components, favorable corrosion resistance and protective anti-corrosion coatings are required. Full article