Search Results (14)

Efficient cooling and heat recovery systems are becoming increasingly critical in large-scale commercial and industrial facilities, especially with the rising demand for sustainable energy solutions. Traditional air-conditioning and refrigeration systems often dissipate significant amounts of waste heat, which remains underutilized. This study addresses the challenge of harnessing low-potential waste heat from such systems to support fifth-generation district heating and cooling (5GDHC) networks, particularly in moderate-temperate regions like Flanders, Belgium. To evaluate the technical and economic feasibility of waste heat recovery, a methodology is developed that integrates established performance metrics—such as the energy efficiency ratio (EER), power usage effectiveness (PUE), and specific cooling demand (kW/t)—with capital (CapEx) and operational expenditure (OpEx) assessments. Empirical correlations, including regression analysis based on manufacturer data and operational case studies, are used to estimate equipment sizing and system performance across three operational modes. The study includes detailed modeling of data centers, cold storage facilities, and large supermarkets, taking into account climatic conditions, load factors, and thermal capacities. Results indicate that average cooling loads typically reach 58% of peak demand, with seasonal coefficient of performance (SCOP) values ranging from 6.1 to a maximum of 10.3. Waste heat recovery potential varies significantly across building types, with conversion rates from 33% to 68%, averaging at 59%. In data centers using water-to-water heat pumps, energy production reaches 10.1 GWh/year in heat pump mode and 8.6 GWh/year in heat exchanger mode. Despite variations in system complexity and building characteristics, OpEx and CapEx values converge closely (within 2.5%), demonstrating a well-balanced configuration. Simulations also confirm that large buildings operating above a 55% capacity factor provide the most favorable conditions for integrating waste heat into 5GDHC systems. In conclusion, the proposed approach enables the scalable and efficient integration of low-grade waste heat into district energy networks. While climatic and technical constraints exist, especially concerning temperature thresholds and equipment design, the results show strong potential for energy savings up to 40% in well-optimized systems. This highlights the viability of retrofitting large-scale cooling systems for dual-purpose operation, offering both environmental and economic benefits. Full article

The adoption of heat pumps in Ukraine is increasing, yet precise data on their economic viability are limited. This study compares the Levelized Cost of Heat (LCOH) in implemented and calculated heat pump systems under Ukrainian conditions. Analyzing real installations and theoretical projects, we assess ground-source and air-source heat pumps, focusing on technical indicators like the Seasonal Coefficient of Performance (SCOP) and economic factors such as the investment costs and discount rates. The findings reveal that promotional materials often underestimate the costs, leading to significant discrepancies in the LCOH. Implemented ground-source heat pump projects have investment costs constituting 20–40% of the LCOH, while for air-source heat pumps, this is 60–65%. The discount rate significantly impacts the LCOH, more than electricity costs. Air-source heat pumps in large buildings offer the lowest LCOH, whereas ground-source heat pumps in small houses have a higher LCOH due to the substantial capital investments. This study concludes that while heat pump systems can enhance energy efficiency and reduce environmental impacts in Ukraine, their economic competitiveness hinges on accurate cost assessments and favorable economic conditions. Full article

This study presents a comprehensive analysis of the energy efficiency and sustainability of Variable Refrigerant Flow (VRF) systems in university buildings during the winter season, offering significant contributions to the field. A novel methodology is introduced to accurately assess the real Seasonal Coefficient of Performance (SCOP) of VRF systems, benchmarked against conventional Heating, Ventilation, and Air Conditioning (HVAC) technologies, such as natural gas-fueled boiler systems. The findings demonstrate outstanding seasonal energy performance, with the VRF system achieving a SCOP of 5.349, resulting in substantial energy savings and enhanced sustainability. Key outcomes include a 67% reduction in primary energy consumption and a 79% decrease in greenhouse gas emissions per square meter when compared to traditional boiler systems. Furthermore, VRF systems meet 83% of the building’s energy demand through renewable energy sources, exceeding the regulatory SCOP threshold of 2.5. These results underscore the transformative potential of VRF systems in achieving nearly Zero-Energy Building (nZEB) objectives, illustrating their ability to exceed stringent sustainability standards. The research emphasizes the strategic importance of adopting advanced HVAC solutions, particularly in regions with high heating demands, such as those characterized by continental climates. VRF systems emerge as a superior alternative, optimizing energy consumption while significantly reducing the environmental footprint of buildings. By contributing to global sustainable development and climate change mitigation efforts, this study advocates for the widespread adoption of VRF systems, positioning them as a critical component in the transition toward a sustainable, zero-energy building future. Full article

The decarbonization of heating systems is one of the present political and legislative directions of the European Union and its Member States. The main activities concern the energy performance of buildings and energy efficiency. The mentioned UE directives are the basis for the financial support of high-emission fossil fuel thermal energy source replacement with emission-free ones, in particular heat pumps. Other aspects are the support of PV installations and the thermal insulation of buildings. 85% of EU buildings were built before 2000, and among those, 75% have poor energy performance. Therefore, a significant number of buildings have only high-temperature wall radiators, and this was a motivation to prepare this article. The main innovation of this research was a new theoretical design of a high-temperature heat pump based on ecological refrigerants. The presented solution allows wall radiators to receive a hot water supply with temperatures of up to 85 °C during external temperatures of up to −20 °C. Typical heat pumps do not have these kinds of parameters, so the authors decided to verify the possibility of operating this device in such a wide temperature range. Another important aspect was the analysis of PV support. Finally, this paper investigates the possibility of heating an energy-efficient house with the newly designed high-temperature heat pump. Depending on the location in Poland, i.e., Suwałki, Warsaw, and Wrocław, the total electric energy supplied to the compressors was 2538–3364 kWh. The energy provided by the PV to supply power to the compressors is 482–570 kWh. The achieved PV energy self-consumption is 16.9–19.0%. The Seasonal Coefficient of Performance (SCOP) of the heat pump is 1.825–2.038 without PV and 2.515–2.970 with PV. Full article

Environment control systems in broiler houses utilize non-renewable electricity and fuels as energy sources, contributing to the increase in greenhouse gases, while not providing optimal conditions. The heat pump (HP) is an energy-efficient technology that can continuously regulate the indoor temperature and relative humidity by combining different operation modes (heating, cooling, and dehumidifying). The current study presents an analytical numerical model developed in Simulink, capable of simulating the thermal loads of a broiler house and the dynamic operation of three heat pumps to cover its needs. Outdoor climatic conditions and broilers’ heat production are used as inputs, while all the heat exchange mechanisms with the external environment are considered. The study investigates the energy use and performance of each HP mode under different environmental conditions. A total of 7 different production periods (PPs) are simulated for a 10,000-broiler house in northern Greece, showing total energy consumption of 18.5 kWh/m², 43.4 kWh/m², and 58.7 kWh/m² for heating, cooling, and dehumidifying, respectively. The seasonal coefficient of performance (SCOP) reaches above 3.1 and 4.8 for heating and dehumidifying, respectively, while the seasonal energy efficiency ratio (SEER) for cooling is above 3.7. Finally, focusing on the two warmer periods, a comparison between cooling with and without evaporative pads was performed, showing similar energy consumption. Full article

Heat pumps in buildings allow for the limiting of CO₂ emissions by exploiting directly the renewable energy available in the external environment (aerothermal, hydrothermal and geothermal sources). Moreover, other renewable technologies such as active solar systems can be integrated easily into use with them. This combination not only increases the share of primary energy provided by renewable sources for heating/cooling but also improves the heat pump performance indices. Nevertheless, in cold climates, air–water heat pumps should be equally penalized due to the unfavorable outdoor air temperature. Conversely, a water–water heat pump, connected with a solar tank and thermal solar collectors, overcomes this issue. Indeed, the higher temperature attainable in the cold source allows for reaching greater COPs, and when the solar tank temperature level is enough, emitters can be directly supplied, avoiding the absorption of electric energy. In this paper, this plant configuration, in which a further tank after the heat pump was considered to manage the produced thermal energy, is investigated. Proper control strategies have been developed to increase the renewable share. Regarding a reference residential building located in Milan, for which the water–water heat pump was sized properly, a parametric study, carried out in TRNSYS by varying solar tank volume and collecting surface, has allowed for the identification of the optimal system configuration. A renewable share, ranging between 54% and 61% as a function of the collecting surface and the storage volume, was detected, as was an average seasonal coefficient of performance (SCOP) over 4. Regarding two common heating plant configurations using an assisted PV air-to-water heat pump and a gas boiler, the optimal solution allows for the limiting of CO₂ emissions by 33% and 53%, respectively. Full article

The seasonal performance of a heat pump indicates its average performance during the heating and/or cooling season, taking into account the different energy demands and their variability over time. Several European and international regulations and policies related with energy efficiency and the reduction of the carbon footprint of energy related products are affecting the heat pump industry. Among them, the ecodesign regulations impose minimum energy efficiency values for heat pumps, efficiencies that are based on the seasonal coefficient of performance. This work is focused on a domestic brine-to-water heat pump for low-temperature applications. The methodology to determine its seasonal coefficient of performance (SCOP) according to the European standard EN 14825 is explained and evaluated based on experimental results. The impact on the SCOP of using some technology options such as fixed or variable speed compressors, and fixed or variable outlet temperature operation is evaluated. Results show that between the lowest and highest efficient option, the SCOP can be improved by 26%. Full article

Air-to-water heat pumps (AWHPs) is a very good option for efficient heating in the residential and commercial building sectors. Their performance and therefore the use of primary energy and CO₂ gas emissions are affected by various factors. The aim of this paper is to present a study on the seasonal coefficient of performance in heating (SCOP) of AWHPs, which are available in the Greek market. The sample consists of 100 models in total, offered by 12 manufacturers, in a range of heat pump’s thermal capacity up to 50 kW. The calculation of SCOP values was performed according to the methodology proposed by the EN14825 standard. The results indicate how the heating capacity, the local climate, the supply water temperature, the compressor’s technology, and the control system affect the seasonal performance of the various AWHP models examined. Setting the SCOP ≥ 3 value as a criterion, the analysis that was carried out in four climatic zones A, B, C, and D of Greece, shows that there are many models that meet this criterion, and, in fact, their number increases from the coldest to warmer climates, in combination with lower water supply temperatures to the heating system and a control system with weather compensation. Full article

In this paper, dynamic simulations of the seasonal coefficient of performance (SCOP) of Air-Source Heat Pumps will be presented by considering three different heat pump systems coupled with the same building located in three different Italian municipalities: S. Benedetto del Tronto (42°58′ North, 13°53′ East), Milan (45°28′ North, 9°10′ East), and Livigno (46°28′ North, 10°8′ East). Dynamic simulations were conducted by employing the software package TRNSYS and by considering real weather data (i.e., outdoor air temperature and humidity as well as solar radiation) referring to the three abovementioned cities for a period of 8 years (2013–2020) and collected from on-site weather stations. Attention has been paid to the modeling of the heat pump defrost cycles in order to evaluate their influence on the unit’s seasonal performance. Results show that, when referring to different years, the thermal energy demand displays huge variations (in some cases it can even double its value), while the effective SCOP is characterized by scarce variability. Sensible variations in SCOP values are achieved for Livigno. Full article

The purpose of this work is a comparison of indirect carbon dioxide emissions between the different heat pump types that operate in Polish climate conditions. This analysis embraces an air–water heat pump (ASHP), ground–water heat pump (GSHP), water–water heat pump (WSHP), and a WSHP with a separating heat exchanger (SHE) in the selected towns, one in each climatic zone in the country. The study starts from a computation of heat demand and electrical energy consumption in every hour of the heating season using temperature values taken from a typical meteorological year (TMY). Then, seasonal coefficient of performance (SCOP) values are determined, which enables an assessment of which kind of heat pump meets the European Union requirements in every location. Eventually, indirect CO₂ emissions that are caused by electrical energy production are estimated for every heat pump in each location. Full article

The energy storage field is nowadays a highly ranking topic. This research deals with the installation and analysis of the ice storage system which combines heat pump, solar absorber, and ice storage tank (phase change material—PCM). This system uses a special kind of solar absorber – header pipes (HDP), which have no thermal isolation compared to the common solar absorber. Thanks to that the HDP, pipes can absorb thermal energy not only from the sun but also from the environment. The rain or snow also affects heat exchange. All that is provided by one technical device. The system can store thermal energy gained from the solar absorber into the ice storage tank for future usage. Research works with data from the real operation, for a period of the year covering all working phases/modes of the system. The analysis of the data led to the identification of several specific modes of the system, especially from the processes taking place in the PCM storage tank during its charging and discharging at various time stages of operation of the whole system. The installation and analysis of the ice storage system probably took place for the first time in Slovakia and Slovak Republic’s conditions. Besides, this system was not installed on a new low-energy house, but on an older family house with thermal insulation. The aim of this installation was also to demonstrate the usability of the ice storage system in an older house and potentially reduce the homeowner’s fees thanks to new technology with higher efficiency. We managed to comprehensively analyze and describe the operation of this system, which also appears to be highly efficient even in a family house with a lower energy certificate, than today’s new low-energy buildings. The results showed a significant efficiency difference in favor of the ice storage system compared to conventional heating systems. The total analysis time was 1616 h and the total efficiency of this heating system—the seasonal coefficient of performance (SCOP) was 4.4. Compared to the average SCOP 3.0 of conventional heating systems for new low-energy houses, the total efficiency increased by 46.6%. These results could therefore be considered as beneficial, especially if we take into account that this system was installed on an approximately 40-year-old family house. The analyzed ice storage system is still working today. The main goals of this paper were to describe the heat pump’s duty cycle with ice storage (PCM) based on real-life data and bring a detailed description of the heat transfer medium behavior at various phases of storing/utilizing heat in the vertical ice storage’s profile for increasing efficiency. Full article

A finned tube heat exchanger is a key component used as a condenser or an evaporator in residential air-conditioning (AC) and heat pump systems. The overall cycle performance of these systems is significantly affected by the heat exchanger’s geometric design. This study investigates outdoor heat exchanger designs with varying geometric parameters such as the fin pitch, number of tube rows, and tube length, and their effect on system performance based on seasonal energy efficiency ratio (SEER) and seasonal coefficient of performance (SCOP). Air face velocity profiles for each operating condition along the outdoor heat exchangers are determined using CFD, with subsequent cycle simulations for 10 different operating conditions. Results have been validated with the available experimental data. The number of tube rows, fin pitch, and length of tube have been varied from 2–10, 1.4–2.5 mm, and 800–2800 mm respectively. The numerical results reveals that SEER increases 3.21% while SCOP increases 5.32% up to fourth and fifth tube row respectively and remain unaffected thereafter. Similarly, SEER increases by 3.55% as the tube length is increased from 800–1800 mm, while it increases only 0.67% for 1800–2800 mm and the maximum variation of 4.32% has been found for SCOP. Moreover, increasing the fin pitch reduces SEER and SCOP (except for fin pitch from 1.4 to 1.8 mm). Finally, the performance of the system with four different fin configurations have also been investigated and it has been found that slit fins are more effective. Full article

The paper presents a parametric study evaluating the effects of various predictive controls on the operating parameters of heat pumps. The heat pump represents a significant power appliance in the residential sector. Its connection to the heat accumulator creates a system with considerable potential to control electricity consumption according to the needs of the electricity grid. The air-water heat pump is considered in this study. A predictive control is used for priority operation of the heat pump at periods of peak power production from renewable sources. The following were tested as the parameters of predictive control: outdoor air temperature, photovoltaic power production and wind power production. The combination of photovoltaic and wind power production was also tested. A parametric analysis considering different sizes for the thermal accumulator and the heating capacity of the heat pump were proposed. The benefits of predictive control are evaluated based on historical records of meteorological data from 2015 to 2018 in the city of Brno, Czech Republic. The data on the historical development of the real electrical energy production from renewable sources in the Czech Republic are used for regulation control in a monitored period. The main comparison parameter is the heat pump seasonal coefficient of performance (SCOP). From the carried out study results, an increase in SCOP by 14% was identified for priority operation of heat pump (HP) at periods with highest outdoor air temperature. Priority operation of HP at periods with peak photovoltaic (PV) production increased SCOP by 10.25%. A decrease in SCOP only occurred in case with priority operation of HP at peak production of wind power plants. Increasing the size of the accumulator contributes to an increase in SCOP in all assessed modifications of predictive control. Full article

A concept of Air-Cooled Heat Pump (ACHP) coupled with a Horizontal Air-Ground Heat Exchanger (HAGHE), also called Horizontal Earth-To-Air Heat Exchanger (EAHX), has been proposed. The Air-Cooled Heat Pump is a system which transfers heat from outside source (air) to inside sink (water) and vice versa in summertime. The innovation is to provide a geothermal treatment of pre-heating/cooling of air before meeting the evaporator in winter or the condenser in summer of the heat pump. Besides, it is known that the variations of the ground temperature, respect to the external air one, are mitigated already in the first layers of the ground throughout the year, due to the high thermal inertia of the ground, letting the heat pump work with more mitigated conditions, improving the performances. The behaviour of HAGHE has been investigated by varying the length and the installation depth of the probes, the air flow rate and the ground thermal properties. All the combinations have been implemented using TRNSYS 17 software (Transient System Simulation Program) to obtain the outlet temperatures from HAGHE, resulting from the 54 configurations. The results are compared in terms of Coefficient of Performance (COP) in wintertime and Energy Efficiency Ratio (EER) in summertime between configurations with and without the coupling with HAGHE. In addition, two seasonal performance SCOP and SEER coefficients have been calculated considering, not only the inlet air temperatures into the Air-Cooled Heat Pump, but also their frequency of occurrence, the off-set external temperature (16 °C), the nominal external temperature and heating and cooling loads. Full article