Air Source Heat Pump System Research Articles

Dynamic Behavior and Energy Performance Analysis of Air Source Heat Pump System in Net-Zero Energy House

Dynamic Behavior and Energy Performance Analysis of Air Source Heat Pump System in Net-Zero Energy House

Investigation of solar assisted air source heat pump heating system integrating compound parabolic concentrator-capillary tube solar collectors

Solar assisted air source heat pump heating systems are capable of achieving green heating where solar availability essentially affects its operation performance and application potentials, especially in higher-latitude regions, such as UK. Compound parabolic concentrator solar collectors can achieve high collector efficiency at high hot water temperature, benefitting to improve solar collection and corresponding thermal energy storage capacities. Though compound parabolic concentrator solar collectors have been widely investigated, application of such collector for solar assisted air source heat pump system is not studied yet. The paper reports numerical simulations of solar assisted air source heat pump heating systems that integrate compound parabolic concentrator-capillary tube solar collectors for domestic heating in the UK. The results show that, for the same seasonal performance factor, the size of the concentrated solar collector required is 12 m2 whereas the size of the flat plate solar collector required is 18 m2. This suggests one third reduction in the size of solar collector, significant reduction in cost and convenience for installation. The results also show the potential to further reduce the size of the concentrated solar collector to 9 m2 or less. The high collector efficiency of the compound parabolic concentrator-capillary tube solar collector enables much small size of solar collector, significantly lower cost and convenient for installation and wide rollout of solar assisted air source heat pump heating system to locations where solar irradiance is relatively lower.

Active Air-Source Heat Storage and Release System for Solar Greenhouses: Design and Performance

The temperature difference between day and night in a solar greenhouse is large. Heat in a greenhouse is typically in excess during the day while the temperature is low and the humidity is high at night. This study designs and tests an active heat storage and release air-source heat-pump system with a thermally insulated water tank as the energy storage body. By comparing air temperature and humidity in a test greenhouse with a control greenhouse in typical weather conditions, the power consumption and performance of the system are evaluated. The results show that compared with the control greenhouse, the average daytime temperature of the test greenhouse is lowered by about 3 °C during the operation of the system in typical weather conditions. At night, the average temperature is increased by about 4 °C, and the relative humidity is decreased by about 20%. When optimized, the maximum coefficient of performance (COP) of the system can reach 4.32 in heat storage mode. The nighttime heat release from the energy storage tank accounts for 26.9% to 51.2% of the nighttime energy consumption, and the energy utilization efficiency is 59.6% to 497.0%. This study provides a new way to control environmental parameters in solar greenhouses.

Experimental investigation on an air source heat pump system with a novel anti-frosting evaporator

The outdoor evaporator of the air source heat pump can easily be frosted during the winter heating operation, which significantly reduces the heating performance. Although anti-frosting and defrosting methods have been substantially researched, the challenges have not been well solved for a long time due to the inability to balance the cost, performance, and reliability. Therefore, to solve this problem, a new bowl shaped finned tube evaporator was proposed to restrain frosting by reducing the frosting driving force and increasing the frost growth resistance through the ingenious use of the fan vortex wind and gravity. A traditional evaporator that has the same finned tube type, total heat exchanger area, and fan power but a different shape structure to the proposed evaporator was selected as the comparison reference. Two experimental testing platforms were constructed to compare the performance characteristics between the proposed evaporator and the traditional one. Results indicated that the system with the proposed evaporator exhibited an increase of 7.4–17.3 % of the coefficient of performance, 100–400 % of the effective heating time, and 0.3–1.4 °C of indoor fan outlet temperature, as compared to the traditional evaporator. In addition, a frost-free area appeared in the proposed evaporator during the frosting period. Therefore, the proposed evaporator has a superior effect on space heating and energy conservation and it has good application in highly humid climates. Further research is recommended to increase the frost-free area and further improve the anti-frosting effect by optimizing the structure.

Technical measures for improving the cold island effect of air source heat pump unit array

In recent years, in response to the call for energy conservation and emission reduction, the air source heat pump systems have been widely applied in regional centralized heating engineering.However, due to the existence of cold island effect, the heat pump unit operation in winter has the problems of low efficiency, high operation cost and insufficient production.This paper takes the heat source station combined with gas source heat pump and electric boiler as an example, and its heat pump unit array was simulated and calculated by analyzing relevant test data and using the numerical calculation method. Some technical measures were put forward to improve the cold island effect, and then the advantages and application scope of these measures are also analyzed.

Technical and economic performance study on winter heating system of air source heat pump assisted solar evacuated tube water heater

Winter heating with clean energy is very important for coal substitution in rural areas of China. In Northwestern China, winter weather is usually below zero and winter heating lasts at least 5 months, which is a big expense for rural residents. It is well known that solar energy, air source heat pump and other energy-saving technologies could effectively cut down the expenditure. However, it is difficult to consider the economics and stability of winter heating with free solar energy alone, and the cost of winter heating with heat pump alone is too high for locals to afford. Therefore, the concept of air source heat pump assisted solar energy was proposed and a solar evacuated tube water heater -air source heat pump system was built in Lvhua Village, Lanzhou City. Experiment and simulation studies were carried out to discover the technical and economic performances when the system operates in three modes, namely, heating by solar water heater, air source heat pump and solar water heat pump (heat pump used hot water from solar collector as heat). Simulation results were verified and highly consistent with experimental results on December 20th, 2021. The results show that in whole heating season, air source heat pump assisted solar energy system greatly improves technical and economic performance in comparison with heating by solar water heater and air source heat pump. The average daily collector efficiency in the heating season is 45.5 %, and the average daily effective solar heat collection is 43.6 kWh. During the heating season, the effective solar heat collection is 6587.1 kWh, the electricity consumption is 5229.7 kWh, the heat supply is 16392.2 kWh, the solar fraction is about 40.2 %, the energy efficiency ratio is 3.1, the average COP of solar water heat pump is 3.5, and the average COP of air source heat pump is 3.0. The primary energy saving rate of the system is 66.4 %, the dynamic investment pay-back period is 6.5 years, and the CO2 emission reduction is 10960.7 kg. The results demonstrate the feasibility of the winter heating system of air source heat pump assisted solar evacuated tube water heater, which provides a new way for the heating of rural single buildings in cold areas.

Multi-objective optimization of a photovoltaic thermal curtain wall assisted dual-source heat pump system

To address the limitations of single renewable energy applications in cold regions, a novel photovoltaic thermal curtain wall assisted dual-source (air and ground source) heat pump system is proposed. The performance of the system was investigated using numerical simulations and experimental tests. Furthermore, a multi-objective optimization based on the non-dominated sorting genetic algorithm was employed to achieve the optimal design of the hybrid renewable system for a nearly zero-energy building in Shenyang, China. The energy consumption, life cycle cost, and photovoltaic power generation of the system were considered as objective functions. A sensitivity analysis was performed to study the effect of the design variables on the objective functions. The results showed that the seasonal coefficient of performance (COP) of the unit and the proposed system were 3.30 and 2.80, which are increases of 6 % and 5 %, respectively, compared with the dual-source heat pump system. According to the Pareto front obtained, life cycle cost is negatively correlated with energy consumption and positively correlated with photovoltaic power generation. When the area of the photovoltaic thermal curtain wall increased from 0 to 15 m2, the energy consumption and life cycle cost were reduced by 253 kWh and 1118 CNY, respectively.

Investigation of the integrated fuel cell, battery, and heat pump energy systems

The integration of an advanced fuel cell battery electric vehicle was proposed to extend the driving range, increase the overall energy efficiency, and produce an additional cabin space heating service for on-board vehicle application in winter. The adopted heat pump absorbs heat from the fuel cell and battery during charging and discharging scenarios at the heat pump's cold end and transfers it to the cabin supply air for cabin heating. A numerical model for the proposed system was developed and validated by published experimental results. A comprehensive evaluation of the influence of fuel cell output current, battery discharging rate, ambient air temperature, evaporator coolant inlet temperature and refrigerant subcooling degree on the Coefficient of Performance (COP), outlet air temperature, and Equivalent Effective Battery Capacity (EEBC) were conducted. In addition, in this study, a detailed comparison of proposed system to previously published existing systems was carried out in terms of COP, heating capacity, EEBC, and operating price in order to examine the advantages of the proposed system. Results showed that the proposed system was not sensitive to ambient air temperature, but evaporator coolant inlet temperature had the greatest impact on COP, compared to other defined independent variables. A maximum COP of 6.07 could be observed when the evaporator coolant inlet temperature was 32 °C. Although increasing fuel cell output current and battery discharging rate could increase heating capacity, it would decrease outlet air temperature as well. The price of a single charging cycle for running for a 4-hour period was estimated. Compared to conventional Electric Vehicle Air Source Heat Pump (EVASHP) system and Positive Temperature Coefficient (PTC) heaters, the proposed system has the lowest cost which was £10.40per charging cycle while the others are £13.8 and £19.2 respectively when providing the same EEBC and heating capacity. Additionally, the payback period was 10,500 charging cycles. Overall, this study provides a potential solution for efficient cabin heating of electric vehicles in extremely cold weather with twice the EEBC of the existing EVASHP system and with 2.8 times of a PTC system both at −20 °C and the operating price is also 1/3 lower than the existing EVASHP. Meanwhile, the COP of the proposed system is 2.3 times that of the existing systems. It can sufficiently increase the driving range of electrical vehicles in winter and eliminate driving range anxiety.

Operational optimisation of an air-source heat pump system with thermal energy storage for domestic applications

Electricity-driven air-source heat pumps are a promising element of the transition to lower-carbon energy systems. In this work, operational optimisation is performed of an air-source heat pump system aimed at providing space heating and domestic hot water to a single-family dwelling. The novelty of this work lies in the development of comprehensive thermal network models of two different system configurations: (i) a standard configuration of a heat pump system coupled to a hot-water cylinder; and (ii) an advanced configuration of a heat pump system coupled to two phase-change material thermal stores. Three different objective functions (operational cost, coefficient of performance, and self-sufficiency from a locally installed solar-PV system) are investigated and the proposed mixed-integer, non-linear optimisation problems are solved by employing a genetic algorithm. Simulations are conducted at two carefully selected European locations with different climate characteristics (Oban in Scotland, UK, and Munich in Southern Germany) over four seasons represented by typical weather weeks. Comparison of key results against a conventional operating strategy reveals that the use of smart operational strategies for the operation of the heat pump and thermal stores can lead to considerable economic savings for consumers and significant performance improvements over the system lifetime. Optimising the operation of the standard configuration leads to average annual cost savings of up to 22% and 20% at the UK and German locations, respectively. The optimisation of the advanced configuration with the two PCM stores shows even higher potential for economic savings – up to 39% and 29% per year at the respective locations – as this configuration allows for greater operational flexibility, and high-electricity-price periods can be almost completely avoided. Depending on the objective function, configuration and location, the system seasonal coefficient of performance varies between 2.4 and 2.8. Lastly, a significant (up to four-times) increase in the fraction of heat pump energy demand covered by an appropriately-sized rooftop PV system is demonstrated, increasing from 8% to 34% at the UK location and from 6% to 24% at the German location. The analysis highlights trade-offs between the objective functions, while the time-resolved results can be used to guide the future development of smart controllers for these applications.

Operation mode performance and optimization of a novel coupled air and ground source heat pump system with energy storage: Case study of a hotel building

The problem of soil heat imbalance in traditional ground source heat pump (GSHP) systems in cold regions hinders the utilization of geothermal energy. This paper takes a hotel building energy supply system as an example to study the feasibility of a coupled air and ground source heat pump system with energy storage. The design intention of the proposed system was to add an air source heat pump (ASHP) and a water source heat pump (WSHP) as auxiliary heat sources to undertake part of the energy supply function of a GSHP. In winter, the system uses the ASHP as the low temperature heat source of the WSHP, so that its heating performance is basically not affected by extremely low outdoor temperatures, with an average system COP of 2.3. Combined with the energy storage (cold and heat storage), the “peak load shifting” of the power grid and the minimization of the system operation cost are realized. The simulation model of the novel system is established and verified by the monitoring data of the system. The operation mode is optimized to maximize the COP of the system, and the defrosting mode of the ASHP and soil heat balance were analyzed. The results show that the optimized defrosting control can increase the heating capacity of the ASHP by 13.9%. In addition, the proposed system can not only maintain the soil heat imbalance rate to 2.6%, but also reduce the operating cost. The calculation shows that compared with the traditional GSHP system, the annual operation cost of the novel system is only 58%, and the carbon emission can be reduced by 7.14%, which has good economic and environmental benefits. The popularization and application of this form of building system in cold regions has a high value.

Comparative Economic and Experimental Assessment of Air Source Heat Pump and Gas-fired boiler: A Case Study from Turkey

Since sustainability has become a major concern in the construction industry, making economically efficient investment decisions in energy conservation are needed to minimize energy consumption for space heating and cooling. Although Air-Source Heat Pump (ASHP) systems are used to meet buildings’ heating and cooling demands worldwide, high initial setup costs limit the widespread use of these systems. This paper presents comparative assessment of ASHP system versus conventional gas-fired boiler system for a real commercial building with a floor area of 2500 m2 in Istanbul, Turkey. The key performance variable, Coefficient of Performance (COP), of the ASHP system was experimentally evaluated. The experimental results revealed that the system’s COP ranged from 3.22 to 4.32, while the outside temperature ranged from 4.8 to 18.6 °C and the supply water temperature ranged from 32.2 to 36.2 °C. Moreover, the economic analysis results showed that despite the high initial cost, ASHP systems are cost competitive against gas-fired boiler in Turkey. ASHP system could reduce the present value of total Life-Cycle Cost (LCC) by up to 26.4% (47,865 USD) compared to the conventional gas-fired boiler system because it can dramatically reduce the energy consumption per year

Hybrid CO2 air source heat pump system integrating with vapor injection and mechanical subcooling technology for space heating of global application: Life cycle techno-energy-enviro-economics assessment

As a heating method for the sustainability of residential buildings in clean space heating, carbon dioxide (CO2) air source heat pump is an environment-friendly solution to replace fuel-fired boiler. Four hybrid configurations of vapor injection integrated with dedicated mechanical subcooling (VI + DMS) technologies are developed, to deal with the problem of traditional CO2 system energy efficiency deterioration in cold regions, and compared with traditional transcritical CO2 baseline heat pump (BASE), R410A heat pump, coal-fired boiler and four CO2 heat pump systems adopting single technique of VI or DMS. Genetic algorithm is utilized to optimize the operation variables. The comprehensive techno-energy-enviro-economics performances of the nine systems among the whole lifetime are assessed. The influences of heating terminal selection and climate condition are discussed for 40 typical cities in 8 climate zones around the world. The results demonstrate a maximum coefficient of performance (COP) is obtained for transcritical CO2 vapor injection heat pump with flash tank and dedicated mechanical subcooling (VI-FT-DMS), and the COP of VI-FT-DMS system using traditional designed radiator as heating terminal is as high as 1.94 at the ambient temperature of −30 °C. The hybrid VI + DMS CO2 heat pump achieves a significant enhancement in heating season performance factor of 10.61 ∼ 30.37 % and the throttling irreversibility can be remarkably reduced with the exergy efficiency promoted by 12.76 ∼ 64.34 %. The life cycle cost is declined by 14.71 ∼ 22.38 % in contrast to BASE, and life cycle carbon emission reduces by 4.77 ∼ 22.12 %, indicating apparent advantage in environmental performance. The hybrid VI + DMS CO2 heat pump system is a promising solution to apply for clean space heating in the cold, very cold and subarctic zones.

Experimental Performance Study of Solar-Assisted Enhanced Vapor Injection Air-Source Heat Pump System

In this paper, a solar-assisted enhanced vapor injection air-source heat pump (SC-EVIHP) system was built to investigate its heating performance in cold regions. A typical-weather day in Harbin was selected for the experiment, and the heating characteristics of the SC-EVIHP system were explored under variable working conditions. The experimental results showed that the system was greatly affected by solar radiation intensity. On typical-weather days in winter, the maximum values for the heating capacity and COP of the system appeared at the time of maximum radiation intensity. Compared with conventional enhanced vapor injection air-source heat pump systems (EVI-ASHPs), the heating capacity and COP were increased by 24.9% and 12.5% at most, respectively. The COP of the system increased by at most 11.1% under conditions where the outdoor temperature was −12 °C and the outlet hot air temperature of the solar air collector was 40 °C. The SC-EVIHP system works well in a low-temperature environment and can be widely applied in cold regions.

Performance Analysis of the Coupled Heating System of the Air-Source Heat Pump, the Energy Accumulator and the Water-Source Heat Pump

In the remote areas of northern China without central heating and gas supply, for users intending to replace coal-boilers, the air-source heat pump system is always questionable due to the contradiction between its heating capacity and user’s heating demand, especially in very cold areas, whose COP and economy is very poor. The accumulator with phase change materials would be a promising one to solve this problem. With the help of TRNSYS software, a heating system coupled with air-source heat pump, accumulator, and water-source heat pump and its operation mode are provided and analyzed based on the heat source renovation demand of a middle school in Tianshui City suburb which has 5560 m2 area to be heated. The average COP simulated during the heating period of the coupled heating system is 2.23. Based on the simulation model and results, the heat source renovation of the middle school in Tianshui City suburb was carried out, its tested and simulated COP over the day was 2 and 2.05, respectively, which also reveals the validity of the numerical method for this problem.

Visualization experiment and numerical simulation on behaviors of gas-liquid falling film flow on the air-side of two-row plain finned-tube heat exchanger

The frost-free air-source heat pump (ASHP) with integrated liquid desiccant dehumidification is a more promising energy-saving alternative to the conventional ASHP unit. The performance of spray-type finned-tube heat exchanger (FTHE), as one of the key equipment of this frost-free ASHP system, is affected by a combination of various factors including wall wettability, liquid film flow pattern, liquid film thickness, velocity distribution in a liquid film, interface wave, interface velocity and so on. To provide a theoretical basis for the operation, design and optimization of high-performance spray-type FTHE, a visualization experiment system and a three-dimensional (3D) numerical model are employed to study the behaviors of counter-current gas-liquid falling film flow on the air-side of two-row plain FTHE under different parameters in the present paper. According to the experimental results, the flow pattern of liquid film on the finned-tube surface is a mixture flow composed of the rivulet flow and the thin falling film flow, demonstrating that the assumption of the uniform distribution for liquid film thickness proposed in previous studies is not completely consistent with the actual situation. Meanwhile, the numerical results indicate that the transient-average film thickness on the surface of two-row plain finned-tube is significantly 18.3% – 32.5% higher than that on the vertical plate calculated by Nusselt's model. After that, the critical gas and liquid Reynolds numbers of the flow pattern transition for the liquid film are obtained, and it is pointed out that the wall contact angle of 10° is more conducive to the formation of complete film flow on the air-side of the two-row plain FTHE within the fin pitch range of 4.8 – 6.0 mm. The changes of the falling liquid film and gas-liquid interface characteristics are fundamentally attributed to the drag effect of the interfacial shear force. Furthermore, there is a cubic curve relationship between average interface shear force and gas Reg. A quadratic curve relation exists between average wall shear stress and gas Reg. At the same time, the velocity of falling film fluid at the bottom region of laminar flow is reduced, resulting from the inhibiting effect of the interfacial shear force.

Integrated operation of PV assisted ground source heat pump and air source heat pump system: Performance analysis and economic optimization

The ground source heat pump (GSHP) system is widely recognized as an efficient, clean and economical renewable energy technology for buildings, and can be utilized for building cooling, heating and hot water supply. In the hot summer and cold winter zones of China, however, the total thermal load (heating load and hot water load) of GSHP systems is greater than the cooling load, which may cause a significant soil temperature drop and GSHP performance deterioration. To solve the above problems, a photovoltaic (PV) assisted GSHP and air source heat pump system (PVGSHP-ASHP) was proposed. This paper investigated the performance and feasibility of the PVGSHP-ASHP system, using a case campus building in Changsha city, China. The PVGSHP-ASHP system was firstly established by TRNSYS, and then, its operational performance was evaluated and compared with the PV assisted GSHP (PVGSHP) system and the PV assisted GSHP and electric heater (PVGSHP-EH) system. Finally, the economic optimization of the integrated operation of the PVGSHP-ASHP system was carried out with the combined simulation of TRNSYS and GenOpt. The results showed that for the PVGSHP system, the soil temperature reduced from 18.1 °C to 11.8 °C after 15 years of operation, which caused a decrease in the annual coefficient of performance of the GSHP (COPGSHP) and an increase in the annual electricity consumption. Although the PVGSHP-EH system can solve the load imbalance problem, its annual lifecycle cost (ALCC) increased by 39.3 % due to the low efficiency of the EH. The PVGSHP-ASHP system can solve the appeal problem with high annual COPGSHP and COPsys values of 3.49 kW/kW and 4.69 kW/kW, respectively, and only 71,700 kWh of the annual electricity consumption, while its ALCC was the lowest at 99,223 CNY, which was 8.1 % lower than the PVGSHP system. After optimization, the ALCC of the PVGSHP-ASHP system reached the minimized value of 91,158 CNY, with a reduction of 8.1 %. These findings can provide new ways to solve the load mismatch problem of GSHP systems while enhancing the system efficiency in the hot summer and cold winter zones of China.

Computational Intelligence Powered Performance Analysis on Phase Change Heat Storage Air Source Heat Pump System.

Aiming at the performance deterioration of air source heat pump at low temperature in cold area, an air source heat pump system with sodium chloride aqueous solution as low temperature phase change heat storage material was proposed to increase the air inlet temperature of the unit under low temperature conditions and improve the low temperature performance of the heat pump unit. The system form, unit energy consumption model, and economic model were given, and the operating economy of the traditional electric auxiliary heat air source heat pump system and the phase change heat storage air source heat pump system were compared through computational intelligence powered methods. On this basis, the operation economy of the heat pump system using different concentrations of sodium chloride solution as the heat storage material was simulated and optimized, and the operation efficiency and energy-saving performance of the system were analyzed by taking an actual residential building in a cold area as an example. The simulation results showed that the Heating Seasonal Performance Factor (HSPF) of the heat pump system using 8.5% sodium chloride aqueous solution as the heat storage material is 2.24, and the HSPF of the traditional electric auxiliary heat pump system is 1.83. Compared with the traditional electric auxiliary heat pump system, the phase change heat storage heat pump system saves heating energy consumption by 19.6% and defrosting energy consumption by 38.8%. The heat pump system using 10% sodium chloride aqueous solution as the heat storage material has the best operating economy, and the system HSPF is 2.33, which saves heating energy consumption by 23.2% and defrosting energy consumption by 34% compared with the traditional heat pump system. The operation condition of phase change heat storage air source heat pump system is stable, and the system performance is significantly improved.

Solar assisted air source heat pump systems for campus water heating in China: Economic optimization of solar fraction design

• TRNSYS software is to simulate the solar assisted air source heat pump system . • The solar fraction design values of solar water heating systems are not economically optimal in China. • Long-term economic optimization of solar fraction design values for solar assisted air source heat pump systems is performed. • An ANN-generated proxy model is to predict the most economical solar fraction design values of solar assisted air source heat pump systems. The solar assisted air source heat pump (SAASHP) system is widely used for campus water heating owing to its cost-effectiveness and cleanliness. In the current design process of the SAASHP system, the solar collector area is determined by the solar fraction ( f ). However, it is difficult to design a cost-optimal f that can comprehensively take the atmospheric factors, device model, electricity price and initial investment into consideration. To address this issue, a SAASHP system that meets the bathing hot water demand of 480 students was established by TRNSYS software, and the cost-optimal solar collector areas and f values for 12 cities across 4 different solar resource regions in China were obtained by the TRNOPT tool of TRNSYS. Moreover, the effects of SC price, electricity price, bathing hot water demand and rated COP of ASHP on cost-optimal f values were investigated by sensitivity analysis. Finally, a proxy model was generated by the artificial neural network toolbox of MATLAB to predict the cost-optimal f values for different scenarios. The results showed that compared to the economically optimized SAASHP system, the designed SAASHP system according to the national design standards for solar heating systems in China has a larger SC area value, leading to an increase in the annual life cycle cost of the system. The difference between the optimized and designed values of solar collector area and f for the SAASHP system was minor in rich resource and sub-rich resource regions but was larger in general resource and poor resource regions. The solar collector price, electricity price, bathing hot water demand and the rated COP of the SAHP were significant factors affecting the annual life cycle cost, the cost-optimal f and solar collector area of the SAASHP system. The proxy model generated by the artificial neural network toolbox of MATLAB can accurately predict the economically optimal solar collector area and f values for SAASHP systems in different cities and system factors, providing a method for the economic design of SAASHP systems in China.

Research on the Performance on Frost-Free Air Source Heat Pump with Waste Heat Desorption

For the novel frost-free air source heat pump system (FASHP), the compressor waste heat is used to assist desorption for the desiccant on the surface of the desiccant coated heat exchange (DCHE). It can promote the desorption efficiency of the DCHE in the FASHP and reduce the energy loss, which means the improvement of the stability and performance. In this paper, a DCHE model is established, and its accuracy is verified through experimental data. The model is then used to analyze the effect of working conditions and structural parameters on the adsorption rate, desorption rate, heat exchange and proportion of latent heat in the adsorption and desorption processes. The results show that the latent heat ratio is higher, the heat exchange of the DCHE is lower and the system performance is better when the temperature of the analytical circulating air increases and the velocity decreases to 25 °C/0.5 m/s. In addition, the performance is greatly affected by the fin length and width. With the increase of parameters, the heat exchange and proportion of latent heat can be increased to 115.9 J and 69.0%.

Performance and optimization of a novel solar-air source heat pump building energy supply system with energy storage

In order to solve the problem that the traditional heat pump system in the cold area of North China cannot supply heat efficiently and stably, a novel solar-air source heat pump system is proposed to meet the needs of building energy consumption. In winter, the latent heat of water in the ice tank is used as the main low-temperature heat source for the heat pump, and the outdoor air is used as the auxiliary heat source. During the day, the solar energy is used to restore the heat of the ice tank, so as to realize the complementary utilization of renewable energy. The air source heat pump can be used for cooling in summer. In addition, combined with night energy storage (cold storage and heat storage), the “peak load shifting” and the minimization of building operation energy consumption and cost are realized. The experimental platform and simulation model of the system are established, and the operation and design scheme of the system are optimized with the optimal economy. The optimization results show that the system can still maintain efficient operation under continuous extreme weather in winter and summer, and the SPF of the system in winter and summer are 2.93 and 2.6, respectively. Solar photovoltaic power generation meets part of the power demand of the system, which can save about 1.85 t of standard coal compared with thermal power generation. Compared with a conventional air source heat pump system, the novel system has better economy and a dynamic investment payback period of 3.86 years. The proposed system presents a way to meet building energy supply that is worthy of popularization and application in cold areas.