Heat Pump Coefficient Research Articles

Development of performance analysis model with numerical and dynamic energy modeling for an integrated PVT-HP system

This study delivers a comprehensive numerical analysis of an integrated photovoltaic/thermal-heat pump (PVT-HP) system, underscored by an innovative three-dimensional thermal energy storage (TES) model. Addressing the limitations of conventional one-dimensional TES models, which struggled with accurately simulating horizontal flows and the fluid state at various facility inlets, this research marks a significant advancement. Our development of a 3D TES model optimizes finite elements to reduce computation time and enhance accuracy, vital for precise energy analysis in buildings and air conditioning systems. The integration of this model with a network model allows for detailed analysis of flow rate changes and their impacts on heat transfer, crucial for the integrated PVT-HP system. Key findings include a 30 % increase in the temperature difference between the top and bottom layers of the TES when the flow rate is reduced from 50 LPM to 20 LPM, and a 1 % decrease in the heat pump's coefficient of performance (COP) with a 10 LPM reduction in flow rate. The study emphasizes that managing the flow rate is key to optimizing temperature gradients and system efficiency. Strategic adjustments in flow rate significantly affect thermal storage and transfer capabilities, proving essential in system performance. This research offers vital insights into optimizing PVT-HP systems, focusing on the importance of flow rate control in improving temperature management and overall system performance.

Centrifugal compressor design and cycle analysis of large-scale high temperature heat pumps using hydrocarbons

Using natural refrigerants in heat pumps, including hydrocarbons, is becoming attractive because of the tightening regulations concerning synthetic refrigerants. In the literature there is lack of studies investigating detailed component design, including compressor design when using hydrocarbons. This study investigates numerically centrifugal compressor design with hydrocarbons for large-scale high-temperature heat pumps. The compressor analysis was combined with a thermodynamic analysis of a two-stage heat pump. The effect of temperature lift and flash intercooler temperature on compressor sizing, rotational speed, efficiency, axial force, and Mach number were investigated. Generally, the use of hydrocarbons with five carbon atoms resulted in higher coefficient of performance and required lower compressor rotational speeds and larger compressor dimensions when compared to the hydrocarbons with four carbon atoms. The simulated rotational speeds were ranging from 8 krpm to 30 krpm, impeller diameters from 0.15 m to over 0.7 m and compressor efficiencies from 77% to over 85%. The use of cyclic molecules, namely cyclopentane and cyclobutene resulted in the highest heat pump coefficient of performance. Also, the flash intercooler temperature had a notable effect on the compressor design and axial force which has to be taken into account in heat pump cycle design.

Study on the optimization of heat loss during operation of air source heat pump based on entransy theory

Existing research on the analysis heat pump operation generally focuses on the efficiency of doing work while ignores heat loss in the transfer process. Hence, heat pumps are often studied based on theory of minimum entropy production. However, this theory is rarely applied to optimizing heat transfer process with?out heat work conversion. Taking the air source heat pump hot water supply sys?tem of a hotel building as an example, this paper simulates the heat production, power and COP of the air source heat pump during operation based on the the?ory of entransy and entransy dissipation proposed by Professor Zengyuan Guo. The findings show that heat pump operates best at inlet water temperatures of 293 K and 298 K, with a COP of 4.8. In the water at a temperature of 298 K, water temperature can be adjusted by the function of heating capacity between 30 kW and 40 kW to minimize the system?s entransy dissipation, where the system?s unit power consumption reaches its minimum at 9 kW, corresponding to an entransy dissipation of 245.4 kJK. This study provides a good research idea to optimize the thermal power conversion process using the theory of entransy and entransy dissipation.

Modeling of thermal processes in vertical heat exchangers of ground-source heat pump

The basic directions for perfection heat supply systems are the tendency of transition to the low-temperature heating systems based at application heat pump installations. We consider heat supply systems with ground-source heat pump. The paper considers modeling the efficiency of ground-source heat pumps with the account of Ukrainian climate conditions. The paper presents the energy performance criteria which show the way to rational implementation of ground-source heat pumps for heating. A computational model based at non-stationary heat exchange processes in elements of ground-source heat pumps is developed. Generalization and analysis of theoretical and experimental dates allow establishing nature of dependence thermophysical properties on temperature insoil around ground heat exchangers during long term operation of the system. Numerical simulation of thermal processes in vertical ground pipes for ground-source heat pump working with low-temperature heating systems has been worked out. The results of numerical modeling demonstrated perfection and technical adaption of ground-source heat pump for low-temperature heating systems with rational using ground energy potential. The novelty of our method is complex usage theoretical and experimental results which enable to prevent freezing in the ground during long term exploitation This provides insights at effects of different resource mixes and may serve as a new approach to analysis of future heat pump systems using ground source energy development.The proposed method contributes to the field of creation and implementation the sustainable heating technologies using renewable energy sources. The ground heat exchange pipes quantities that are necessary for effective operation heat pump installation, capacity and coefficient of performance with the account of climate conditions are calculated.

Performance evaluation of transcritical CO2 desiccant heat pumps for electric vehicles

Transcritical CO2 heat pump systems are eco-friendly and have excellent heating performance, which makes them suitable for electric vehicles. The recirculation mode can save energy but requires a dehumidification function to ensure driving safety. Therefore, this paper proposes a transcritical CO2 desiccant heat pump, which differs from the typical transcritical CO2 heat pump system by incorporating an indoor evaporator and a full-pass throttle valve. The flow area of the full-pass throttle valve can be adjusted to obtain the appropriate dehumidification rate. In addition, this study suggested using the desiccant heat pump coefficient of performance (DHCOP) to evaluate the overall energy efficiency of the heat pump system. We have investigated the dehumidification rate and optimal discharge pressure under different operating conditions. The results show that even under the harsh operating conditions at -10 °C, the HDCOP of the transcritical CO2 desiccant heat pump can still exceed 2.1, and reach 3.12 at a moderate condition of Ta=5 °C. The transcritical CO2 heat pump desiccant system demonstrates significant energy-saving potential.

Reducing the specific energy use of seawater desalination with thermally enhanced reverse osmosis

This study investigates the concept of using heat to enhance reverse osmosis (RO) desalination. An analytical model is used to evaluate the effect of temperature on water permeate flux, specific energy, permeate quality, and applied operating pressures. When feed is heated from 20 to 50 °C, specific energy savings of up to 24 % are observed for high flux seawater desalination and up to 33 % for brackish water. Such improvements are consistent with the literature, but until now the thermal energy input required to heat feed has been mostly neglected from analysis. For the first time, the overall energy balance of thermally-enhanced RO is considered to evaluate the tradeoff between savings in mechanical pump work and thermal energy input. Results suggest that this tradeoff is favorable under the right conditions. In particular, there is a need for high thermal efficiencies including both a very high heat pump coefficient of performance and very high heat exchanger efficiency for recycling thermal energy. Under these conditions, overall energy savings of up to 12 % are observed for seawater desalination when feed is heated from 20 to 41 °C, and up to 18 % for brackish water with feed heated to 46 °C.

Research on renewable energy coupling system based on medium-deep ground temperature attenuation

Medium-deep geothermal has large reserves, a high temperature, a high heat flow density, and other characteristics, but the traditional medium-deep ground heat pump system have long relied on heating from the ground, and soil temperature decreases annually. Using a community building heating system as an example, from a point of view of heat accumulation or not, this article examines the design of a photovoltaic photothermal coupled medium-deep ground source heat pump system (PV/T-GSHP) and a photovoltaic-assisted medium-deep ground source heat pump coupled air source heat pump system (PVGSHP-ASHP). First, the operational performance of a typical GSHP system was compared to that of the PV/T-GSHP and PVGSHP-ASHP systems, both of which were built using TRNSYS. Second, the energy balance and electrical consumption of each system were compared. Finally, the effect of the PV/T-GSHP system’s key parameters and the different ASHP load ratios in the PVGSHP-ASHP system on soil temperature were analyzed. The results showed that after 20 years of operation, the average soil temperature decreased from 38.29 °C to 36.89 °C for the GSHP system, resulting in a decrease in the performance coefficient of the ground source heat pump and the system performance coefficient. The PV/T-GSHP system can address the issue of declining soil temperature with an increase in soil temperature of 0.09 °C. The PVGSHP-ASHP system can mitigate the issue of decreasing soil temperature. The PVGSHP-ASHP system is better than the PV/T-GSHP system in terms of electricity economy. In the PV/T-GSHP system, the larger PV/T component area of similar structures, the smaller flow rate of the heat collector pump, and the volume, inclination, and set temperature of the heat storage tank that are more suitable for the system can achieve higher soil temperatures. As the air-source load ratio increases, the rate at which the soil temperature in the PVGSHP-ASHP system decreases progressively decelerates.

Technical and economic analysis of multi-energy complementary systems for net-zero energy consumption combining wind, solar, hydrogen, geothermal, and storage energy

An integrated renewable energy supply system is designed and proposed to effectively address high building energy consumption in Zhengzhou, China. This system effectively provides cold, heat, and electricity by incorporating various clean energy sources such as wind, solar, hydrogen, and geothermal energy. Technical and economic analyses are conducted to optimize the integration of these renewable sources. Technical and economic analyses are conducted to optimize the integration of these renewable sources. Rigorous system modeling and dynamic simulation using TRNSYS software evaluate the seamless integration and optimal functioning of the PV/T subsystem within the CCHP system. The interaction between Photovoltaic/Thermal (PV/T) and borehole heat exchanger (BHE) coupling is investigated, analyzing their impact on individual system performance. Furthermore, key indicators, including overall electricity consumption (OEC), life cycle cost (LCC), heat pump coefficient of performance (COPHP), and system coefficient of performance (COPSYS) are analyzed. The robust response surface methodology (RSM) and Box-Behnken experimental design approach are employed to show remarkable agreement between predicted and simulated values, with a maximum deviation of only 1.45%. The optimal configuration consists of a PV/T area of 132 m2, 20 wind turbines, 12 alkaline fuel cells, and 17 borehole heat exchangers, resulting in highly favorable outcomes: an OEC of −35648.72 kW∙h/year, an LCC of $209113.85, a COPSYS of 2.91, and a COPHP of 3.82. Moreover, detailed assessments of each subsystem's performance enhances our understanding of the system's overall operation, affirming the feasibility of the proposed integrated energy supply system for buildings.

A numerical study on performance efficiency of a low-temperature horizontal ground-source heat pump system

Exploitation of shallow ground and its low-grade heat potential is fundamental to designing 5th generation district heating and cooling (DHC) networks. Horizontal ground-source heat pump (HGSHP) systems are a common way to utilize shallow geothermal energy. Realistic estimation and prediction of performance of a HGSHP system and shallow ground thermal behaviour should consider the whole system including building heating and cooling load, heat pump and ground heat exchanger, and the ground. This should be accompanied by realistic atmospheric and ground conditions. In this paper, a three-dimensional coupled thermal–hydraulic model with realistic boundary conditions adopting a whole system approach is presented. Dynamic heat pump coefficient of performance (COP) that depends on seasonal variation of heating/cooling demand and ground conditions are also considered. Model validations are conducted against experimental and analytical results in literatures. The model is applied for evaluating a HGSHP system to support development of a 5th generation DHC network on a potential site in the UK. Several influencing factors, such as ground moisture transfer, building thermal load mode, buried depth of ground loops, and initial ground temperature profile are studied to assess performance efficiency of the HGSHP system and evolution of ground thermal behaviour in response to heat extraction or rejection into the ground. The results show that 5% of the monthly total heat demand of the site could be met by the designed HGSHP system, consisting of 200 U-shaped ground loops buried at the depth of 3 m and pure water as the heat carrier. Overlooking the ground moisture transfer or hyperbolizing the ground saturation would overestimate the load-carrying capacity of the HGSHP system. The HGSHP system is more efficient with a higher heat pump COP under the heating and cooling mode than under the heating-only mode. Predicted performance of the HGSHP system improves with buried depth of the ground loops. The results also show that a 1 ℃ increase in the undisturbed ground temperature could suffice up to 8% of the monthly total heat demand of the site.

Reducing industrial hydrogen demand through preheating with very high temperature heat pumps

Decarbonising industry while maintaining economic competitiveness and improving living standards is one of the main challenges of reaching net zero targets, and low-carbon process heating will play a key role in this. In this work we investigate the potential to reduce the energy demands of hydrogen-based industrial heating systems using very high temperature reverse Joule-Brayton cycle heat pumps as preheaters, considering their economics and technical challenges. A thermodynamic process model is used to assess performance at temperatures of 300–500 °C, and cost optimisation is used to conduct cost-benefit analysis of preheating green hydrogen using heat pumps. It is found that over this temperature range, heat pump coefficient of performance lies in the range 1.4–1.7, with the turbine meeting 30–40% of the compressor load. At the electricity prices currently paid by heavy industry in Western Europe, levelised cost of heat from these heat pumps would be less than 4.5p/kWh. Using 500 °C heat pumps as preheaters in hydrogen heating systems could reduce hydrogen demands by over 20% and provide savings on the cost of green hydrogen of at least 8% out to 2050. With process heat accounting for three-quarters of industrial energy use and half of this being at temperatures above 400 °C, these savings are significant and suggest that very high temperature heat pumps could make an important contribution to industrial decarbonisation.

Exergy and exergoenvironmental assessment of a geothermal heat pump and a wind power turbine hybrid system in Shanghai, China

Geothermal heat pumps are one of the most growing and cost-effective renewable energy technologies based on the temperature difference between the ground and the environment. In the cold seasons, the temperature inside the soil or water is higher than the ambient temperature. Therefore, the heat pump is used to extract the warm temperature of the ground into the house or any other controlled space. In the summer, the air temperature is higher than the temperature of the soil or water. This temperature difference is used again to cool the house or any other environment. This paper examines the energy and exergy assessments of a hybrid system in Shanghai, China, that employs a geothermal heat pump with an economizer for winter heating and a wind turbine to provide clean electricity. The complete set of procedures, as well as every component and every aspect of the hybrid system, have all been carefully examined. The heat pump's coefficient of performance is 3.916, its net power output is 22.03 kW, its overall energy efficiency is 77.2%, and its exergy efficiency is 25.49%.Graphical

Performance Analysis of Solar Assisted Ground Source Heat Pump to Supply Heating Load and Domestic Hot Water

Algeria’s geographical location offers several advantages related to the extensive use of renewable energy sources such as solar and geothermal. Owing to the vast Algerian territory, the need for isolated areas to be supplied with energy by autonomous systems using sustainable energy. In this study, we propose a hybrid renewable energy system to provide heating systems for residential buildings and domestic hot water (DHW). Four different solar-assisted ground source heat pump (SAGSHP) combinations are being studied, with the aim of satisfying the energy needs of a building located in Batna, Algeria. The TRNSYS software allowed us to study the different effects of the parameters on their performance. It turned out that a 7.7 kW ground source heat pump system combined with flat solar collectors is a feasible choice that satisfies our objective. The extreme annual average values of the heat pump coefficient of performance (COP) obtained are 3.48 and 4.55. In the system, with recharging the borehole, the net energy extracted from the ground is decreased by 30.4% compared to the reference case (GSHP). This can reduce the ground thermal imbalance problem, which positively affects the stability of the operational system.

INFLUENCE OF PRESSURE IN THE TURBINE CONDENSER ON HEAT SUPPLY EFFICIENCY OF NPP WITH HEAT PUMP

The use of a heat pump for heat supply makes it possible to practically stop thermal pollution of the environment during the operation of thermal and nuclear power plants in winter. If a steam turbine condenser is used as a low-potential energy source for heat pump, the amount of released thermal energy will be equal to the sum of the thermal power of the NPP condenser and the power of the heat pump compressors. From the point of view of environmental safety, heat supply by combining power plant with a heat pump is an urgent task. But it is known that the due to the lack of steam extraction for water heating, the additional electrical power of the cogeneration heat and power plant will be less than the capacity of the heat pump compressors. Thus, in terms of thermodynamic efficiency, the use of a heat pump loses to a traditional cogeneration plant. The purpose of the work is to determine the influence of the final pressure in the turbine condenser on the thermodynamic efficiency of a nuclear power plant with a heat pump. A mathematical model of the thermal scheme of the K-1000-5.8/1500 NPP turbo-plant during summer and winter operation with heating plant has been developed. With the heating plant capacity of 230 MW, the electric capacity of NPP unit decreases by 43.5 MW. A mathematical model of a heat pump has been developed, for which a steam turbinecondenser is used as a low-potential energy source. To ensure the release of 230 MW of heat, the power of the heat pump compressor must be 48.4 MW. Thus, if the heating plant is replaced with a heat pump of the same capacity, the electric power will decrease by 4.8 MW. Calculations were made regarding the influence of the final pressure in the condenser on the exergetic efficiency of the NPP with heat pump, which uses the entire capacity of the turbine condenser. The analysis of the obtained results showed that the exergetic efficiency due to the increase in electric power released in winter increases with the increase of the final pressure in the condenser. This is explained by an increase in the heat pump coefficient of performance.

Theoretical Study of HFO1336mzz(Z)/HFO1224yd(Z) Refrigeran t Mixtures for High-temperature Heat Pump

Background: The global energy consumption problem is becoming more serious, therefore, it is a hot trend to improve energy efficiency and choose environmentally friendly alternative working fluids. Objective: The main thermophysical parameters of the refrigerant mixture, which blended HCFO 1224yd(Z) and HFO1336mzz(Z) in the high-temperature heat pump cycle, were theoretically studied to replace HFC245fa. The theoretical cycle model of refrigerant mixtures of high-temperature heat pumps was established. Methods: In this paper, a theoretical cycle model of the mixed refrigerant high-temperature heat pump is established, and the cycle performance of the mixed refrigerant in the high-temperature heat pump system under different working conditions is compared. Results: It was found that HFO1336mzz(Z) could reduce the exhaust temperature of the compressor and increase the heat pump coefficient COPh, and HCFO1224yd(Z) could improve the problem of excessive suction specific volume in high-temperature heat pump systems. Conclusion: The result shows that the refrigerant mixture with 0.6/0.4 HCFO1224yd(Z)/HFO1336 mzz(Z) has the best cycle performance when the condensing temperature is 150 °C, and the cycle temperature rise ranges from 50 to 70°C.When the cycle temperature rise is 70°C, and the condensing temperature ranges from 110 °C to 150°C, the coefficient of performance value of the refrigerant mixture with 0.2/0.8 HCFO1224yd(Z)/HFO1336mzz(Z) reaches the maximum of 3.11.

건물유형 및 지역을 고려한 하천수 이용 수열 히트펌프 시스템의 연간 성능 분석

Recently, as interest in renewable energy has increased, research in various fields has been continuously conducted. Among them, interest in hydrothermal energy is increasing due to the revision of the enforcement decree in 2019. However, although various studies have been conducted on system demonstration, performance and economic feasibility analysis, heat exchangers, etc., studies on the performance of the water heat pump system considering the domestic region and building type are insufficient. Thus, in this study, an annual performance analysis of the water source heat pump system was performed using dynamic energy simulation considering the domestic region and building type. The regions were assumed to be Seoul, Daejeon, Busan, and Gwangju, and the building types were assumed to be office buildings, apartment houses, and greenhouses. As a result of heat pump Coefficient of Performance(COP) analysis, the cooling COP was an average of 4.01 by region and 3.99 by building type. Heating COP was 3.13 and 3.43, respectively. Also, when comparing the performance deviations by region and building type, the heating performance differed greatly depending on the building type, and the cooling performance showed a significant difference according to the region. Overall, it was confirmed that the cooling performance of the hydrothermal heat pump system was approximately 15% superior to the heating performance.

MATHEMATICAL MODELLING AND OPTIMIZATION OF MELON SLICE DRYING WITH RESPONSE SURFACE METHODOLOGY IN A HEAT PUMP DRYING SYSTEM

The objective of this study was to optimize the process conditions (in terms of air temperature, air velocity and thickness of the slices) using response surface methodology (RSM) to achieve minimum specific energy consumption and maximum moisture diffusivity during drying of melon slices with a closed loop heat pump drying (HPD) system. An optimum drying temperature of 45 °C, air velocity of 1 m/s and slice thickness of 5.04 mm were recommended with following predicted responses close to experimental values: drying time 216.58 min, total energy consumption 2.94 kWh, coefficient of performance heat pump (COPhp) 3.08, coefficient of performance system (COPws) 2.75, specific moisture extraction rate (SMER) 0.22 kg/kWh, drying rate 2.53, L* value 82.53, a* value -1.83 and b* value 25.82. The most suitable models to represent the drying behavior of optimum melon slices was chosen Wang & Sing. Effective moisture diffusivities (Deff) of the melon slices were ranging from 7.075E-10 - 1.843E-07 m2s-1 and increasing drying air temperature, drying air velocity and slice thickness led to an increment of Deff.

Onsite measurement and performance analysis of capillary heat pump system used in subway tunnels

This study proposed a ground source heat pump system using capillary networks as the front-end heat exchanger, to alleviate thermal pollution and utilize waste heat generated in subway tunnels and the surrounding rock. We conducted onsite measurement of the capillary ground source heat pump system based on a real engineering project involving a subway tunnel. Subsequently, the heat transfer performance of the capillary heat exchanger and energy efficiency of the system were analyzed. The heat transfer capacity of the capillary heat exchanger was approximately 45–80 and 100–110 W/m2 in a test with a duration of 7 h in winter and a test with a duration of 14 h in summer, respectively. The average coefficient of performance of the heat pump unit and coefficient of performance of the system were 3.72 and 3.18, respectively, in winters, and 3.19 and 2.64, respectively, in summers. Under a 4-day test with an intermittent operation of 8 h per day in summer, the performance of the system was improved and remained stable for four days during the test. The average coefficient of performance of the heat pump unit and of the system for intermittent operation were 3.67 and 2.96, respectively, which were larger than those for 14 h continuous operation in summer. In practical applications, intermittent operation or additional auxiliary cooling sources are recommended in summer conditions.

A method to evaluate the performance of an open loop geothermal system for mine water heat recovery

Purpose. To develop a method to evaluate hydrodynamic and thermal parameters of an open loop geothermal system with the discharge into surface water bodies as well as to test the method under real site conditions considering different technology options, geotechnical and thermodynamic factors. Methodology. We employed the relations of hydraulics and thermodynamics, performed an engineering review of open loop geothermal systems for mine water heat recovery, studied hydrodynamic and mining conditions of the colliery Novohrodivska No.2. The developed technique includes evaluating the temperature of rocks around flooded workings, the length of the hydraulic path and flow resistance of workings. Findings. The evaluated temperature of mine water entering on-ground heat exchangers ranges at 17.8 0.25 C, and the system thermal output is 1070 21 kW. Water temperature in flooded workings due to dilution with infiltration during the operation period of 25 years is expected to fall by 0.61.0 C, which decreases the thermal output by 5.68.3%. The estimated cooling of water during its rise in the shaft does not exceed 1C. The criterion of the geothermal system energy efficiency decreases from 1.8 when pumping close to the mine water level to 1.05 when pumping 460 m below the ground; the heat pump coefficient of performance (COP) reaches 5.0. Originality. The flow characteristics and hydraulic flow lengths at different horizons, the temperature of rocks around workings were found to be the dominant factors for the thermal output under steady flow. The pumping depth was proved to significantly affect the energy efficiency of the system. Practical value. The proposed method allows quantifying the energy criterion of an open loop geothermal system with the discharge into surface watercourses, which enables optimizing system performance indicators.

ПОРІВНЯЛЬНИЙ АНАЛІЗ ГЕОТЕРМАЛЬНОГО ПОТЕНЦІАЛУ ЗАКРИТИХ ШАХТ ДОНЕЦЬКОГО ТА РУРСЬКОГО ВУГІЛЬНИХ БАСЕЙНІВ

Purpose. This study aims to perform a comparative analysis of the geothermal potential for closed mines in the Donbas and Ruhr regions in terms of the operation efficiency of geothermal systems of various types. Methods. The proposed approach includes ranking closed mines in the Ruhr (Germany) and Donetsk (Ukraine) coalmining areas according to the major parameters of geothermal system efficiency that includes the maximum and net thermal capacity, heat pump coefficient of performance COP, energy efficiency of heat recovery. The last parameter, introduced by the authors earlier, is defined as the ratio of the produced thermal energy to the thermal equivalent of the electricity required for running the heat pumps and the heat transfer fluid circulation. Results. The average expected thermal capacity of open loop geothermal systems at mine drainages in Germany was found higher than the similar indicator for the selected mine drainages in Ukraine, with slightly lower indicators of mine water heat recovery compared to the drainages in the Donbas. The average expected thermal capacity of closed loop geothermal systems based on coaxial probes at the current water level in the mines of two areas is estimated to be within the range of 30-34 kW, and the average indicators of geothermal heat recovery in the mines of two areas differ by no more than 5%, while the mines in the Donbas demonstrate a higher dispersion of calculated indicators. Similarity of operating conditions and energy efficiency indicators of geothermal systems evaluated for two areas indicates the feasibility and the potential of operating such systems in Ukraine. Scientific novelty. The approach to ranking of closed mines according to their geothermal potential based on parameters of mine water heat recovery efficiency has been substantiated and implemented. The developed approach enables identifying the promising sites to install geothermal systems of various types at inactive mines. Practical significance. The proposed approach allows to preliminarily evaluate the ranges of indicators for the effective operation of geothermal systems of various types with identification of the most promising areas for further detailed technical and economic justifications.

Decreasing the Load of Air to Water Heat Pump Systems on Electrical Grids

Abstract This article focuses on decreasing the energy taken from the electrical grid by air to water heat pumps in buildings that use renewable energy. Conventionally the majority of the produced renewable energy is not used directly to operate the heat pump. An energy management concept was developed, with a main new parameter – RCOP that enables to create an optimal working schedule that considers the renewable energy availability and heat pump coefficient of performance in relation to the weather. The concept was proven with computer models that use weather forecasts, renewable energy production, and heat demand. The achieved yearly savings in grid-electricity used by the heat pump were 14.3 %. The fluctuations in the grid load were decreased which as well were quantified by a lower standard deviation of the demand. In months with the best renewable energy availability, the grid electricity savings can reach up to 70 %.