Electric Heat Pumps Research Articles

Decarbonization of the heating sector from a system point of view: the case study of the Lombardy Region.

This work aims at defining the optimal technological mix which minimizes the total cost of the energy system in 2030 in the Lombardy region, in northern Italy. The goal is reached through a bottom-up model built on a linear optimization problem considering different technical and economic inputs and constraints. Civil sector is one of the sectors to focus on for the decarbonization process. Different areas, types of buildings and thermal systems are included in the model to consider the peculiarities of the available solutions in each context. The overall technological mix is constraint by a CO2 emission limit. For the civil sector the more the emission is constrained, the higher is the penetrations of electric heat pumps, coupled with envelope retrofit, (10% of the total thermal energy demand) and of district heating (18%), while natural gas boilers decrease (66%). Biomass boilers reach a maximum penetration of 29% in mountain areas. District heating is relevant in areas with available sources (max 29%). Natural gas boilers coupled with air conditioners have an important role and they reach a maximum penetration of 89% in certain areas. Electric heat pumps are quite homogeneous through the areas for residential buildings.

Research on Fuzzy Control Strategy of Heating Condition Based on Electric Vehicle Heat Pump Air Conditioner

The performance of heat pump air-conditioning system under heating conditions is studied, and a fuzzy control strategy is proposed. The heating condition model of the heat pump air conditioning system is built in AMESim, and the control strategy model is established by Simulink for joint simulation, with the cab temperature as the target temperature of the system performance. Compared with the traditional control strategy, the control strategy designed in this paper can rapidly increase the temperature of the passenger compartment to the target temperature, and the temperature control accuracy is more accurate, the callback time is shorter, and the comfort is better.

Stochastic Operation Optimization of the Smart Savona Campus as an Integrated Local Energy Community Considering Energy Costs and Carbon Emissions

Aiming at integrating different energy sectors and exploiting the synergies coming from the interaction of different energy carriers, sector coupling allows for a greater flexibility of the energy system, by increasing renewables’ penetration and reducing carbon emissions. At the local level, sector coupling fits well in the concept of an integrated local energy community (ILEC), where active consumers make common choices for satisfying their energy needs through the optimal management of a set of multi-carrier energy technologies, by achieving better economic and environmental benefits compared to the business-as-usual scenario. This paper discusses the stochastic operation optimization of the smart Savona Campus of the University of Genoa, according to economic and environmental criteria. The campus is treated as an ILEC with two electrically interconnected multi-energy hubs involving technologies such as PV, solar thermal, combined heat and power systems, electric and geothermal heat pumps, absorption chillers, electric and thermal storage. Under this prism, the ILEC can participate in the day-ahead market (DAM) with proper bidding strategies. To assess the renewables’ uncertainties, the roulette wheel method is used to generate an initial set of scenarios for solar irradiance, and the fast forward selection algorithm is then applied to preserve the most representative scenarios, while reducing the computational load of the next optimization phase. A stochastic optimization model is thus formulated through mixed-integer linear programming (MILP), with the aim to optimize the operation strategies of the various technologies in the ILEC, as well as the bidding strategies of the ILECs in the DAM, considering both energy costs and carbon emissions through a multi-objective approach. Case study results show how the optimal bidding strategies of the ILEC on the DAM allow minimizing of the users’ net daily cost, and, as in the case of environmental optimization, the ILEC operates in self-consumption mode. Moreover, in comparison to the current operation strategies, the optimized case allows reduction of the daily net energy cost in a range from 5 to 14%, and the net daily carbon emissions in a range from 6 to 18%.

Comparative energy and environmental analysis of different small-scale biomass-fueled CCHP systems

Biomass combined cooling, heating, and power (CCHP) systems promote energy efficiency and reduce overhead costs in bioenergy production. On the necessity of assessing the sustainability of bioenergy technologies, this study performs a comprehensive life cycle assessment (LCA) of small-scale biomass CCHP technologies regarding technical alternatives. The novelty stems from comparing configurations based on sustainability indicators, the energy payback time, and conflicting objectives (maximizing energy revenues and minimizing environmental costs). Accordingly, four configurations attributed to biomass conversion technologies (organic Rankine cycle (ORC) and gasifier) and cooling units (electric heat pump, absorption chiller) are considered for LCA modeling. The results reveal that the highest share of human health (70–85%), ecosystem quality (50–60%), climate change (60–80%) and resources (70–80%) in all configurations belongs to biomass conversion technologies. In terms of Global warming, impacts related to gasification-ICE-based configurations outweigh ORC-based configurations (30–47%) due to higher auxiliary energy demand in the gasification process. In contrast, the CCHP systems driven by ORC are more reliable in refunding primary energy in the short term, 2.4–2.8 years. As a final result, the gasifier coupled with the electric heat pump is the most optimum configuration due to higher energy profits and lower environmental costs.

An assessment of the impacts of heat electrification on the electric grid in the UK

To achieve net zero emissions by 2050, the world economy needs to be significantly decarbonized. Among all sectors, the decarbonization of heat is likely to incorporate a significant electronification using electric heat pumps, placing additional strain on electric grid infrastructure in countries like the UK. In this paper, we present an assessment of the impacts of heat electrification on the grid in the UK in 2050 when the net zero is reached. A high-resolution heat demand forecasting model is developed to estimate hourly heat demand at the national level and it is validated using published historical data. The validated model is then used to predict the hourly heat demand of the UK in 2050. The impact of heat electrification is then analysed based on several different scenarios. The results show that heat decarbonization through electrification will have a significant impact on the grid. In the case of extreme global warming, both hourly peak demand and annual total heat demand will drop by about 45% in 2050, compared with published data in 2010. In the case of 100% electrification with no global warming, the total annual electricity demand for heating is 109.4 TWh. The hourly peak demand of electricity will increase from 96.6 GW to 146.7 GW, which requires an increase of electricity generation capacity by around 50%. It is however economically infeasible and unviable to build such a huge new generation capacity that would only be used in winter when the peak heat demand peaks but will be switched off during summer. Hence, mitigation measures such as heat storage will play a vital role in balancing power generation and consumption, as well as reducing the required new generation capacity.

Development of the effective defrosting criterion for electric vehicles transcritical CO2 heat pumps under constant heating capacity operation

Passenger comfort takes precedence over heating performance for electric vehicle heat pumps. However, frost formation will cause the heat exchange performance to decrease, leading to the heating capacity dissipation. The dynamics of an electric vehicle CO2 heat pump under constant heating capacity operation during the frosting process were revealed. Moreover, it was found that the dynamic characteristics of parameters under constant heating capacity operation were significantly different from those under constant compressor speed operation. The application of defrosting initiation judgment criteria based on traditional heat pumps to electric vehicle heat pumps would lead to some serious false defrosting phenomena and even damage the compressor and pipelines. Therefore, a new defrosting initiation criterion was proposed for electric vehicle heat pumps based on the dynamic characteristics. Then, the reliability of the new initiation was verified by applying it in different heating demand operations. Finally, the average performance of electric vehicle heat pumps adopting the new defrost initiation was compared with the traditional PTC auxiliary heating method. The conclusion demonstrated that the heat pump with the new defrost initiation criterion had obvious performance advantages under different environmental conditions.

Building decarbonization: Assessing the potential of building-integrated photovoltaics and thermal energy storage systems

The significant share of the building sector in Greenhouse Gas (GHG) emission and final energy consumption makes it a significant target for decarbonization programs. Different standards and technological roadmaps propose several technical solutions to mitigate buildings’ climate change impact, such as improving existing and new buildings’ energy and environmental performance by utilizing Renewable Energy Sources (RES) and Energy Storage Systems (ESS). This study aims to examine and quantify the potential of two recommended solutions with a Life Cycle Assessment (LCA) approach, including Building-Integrated Photovoltaic (BIPV) and Thermal Energy Storage (TES) systems, to achieve the building decarbonization targets. Therefore, a residential building is analyzed under three different scenarios, and the CO2 equivalent emission alongside the avoided carbon emission and Environmental Payback Period (EPBP) of each scenario are assessed and compared.The result shows that applying a coupled BIPV-TES system in a residential building equipped with electric heat pumps can reduce CO2 eq emission by 21.42% over 30 years of the building service life.

Analysis of COVID-19 crisis-related building energy retrofit incentives in Italy

The advent of the COVID-19 pandemic led to an economic crisis of the construction industry and to an increasing of energy consumption in the residential sector for all the world. The European Union highlights the crucial role of building sector for both energy gains and economic growth, defining a “Renovation Wave” plan combining regulation, financing and technical support with the aim of greening the buildings, creating jobs and improving lives. In Italy a great support mechanism for energy refurbishment of existing buildings has been launched by means of tax deduction of 110% over 5 years. The present study aims to analyze this new funding mechanism, under energy, environmental and economic point of views. By means of a real case study, representative of highly widespread southern Italy HVAC-building system, it will be highlighting advantages and contradictions of the incentive mechanism developed, proposing possible future improvements. It is found that, if on one hand, the best refurbishment measure under energy/environmental point of view is the external insulation, windows replacement, electric heat pump and PV-system installation, with a global not renewable performance index reduction of 81%, on the other hand it is not the best solution considering the cost/saving ratio.

Experimental investigation on dehumidification and heating performance of a heat pump system concerning dew or fog removal for electric vehicles

Dehumidification and heating of electric vehicle heat pump systems are of significance in ensuring comfort and safety in winter. This study purposes to investigate the dehumidification and heating performances of a new-designed heat pump system. A numerical model is established and serves for analyzing the ventilation conditions for dew or fog removal of the windshield. Both ventilation conditions of the heat pump and the inner surface temperature of the windshield were investigated as per experimental measurements. Meanwhile, dehumidification rates, effective heating capacity, and coefficients of performance were analyzed under different operating conditions. It is shown that the heat-pump’s air outlet conditions are within the range of suitable ventilation conditions meeting the needs of dew or fog removal. At the same compressor speed, the inlet air humidity of the evaporator inlet decreases, the dew or fog removal is more effective, and the coefficient of performance for heating increases but the coefficient of performance for dehumidification decreases. In the case of the same inlet air humidity, the dew or fog removal effect is better with increasing compressor speed; Meantime, the coefficient of performance for heating and dehumidification both decrease. The lower compressor speed and lower inlet air humidity for the evaporator enable the heat pump system to meet the demand for dew or fog removal of the windshield and ensure thermal comfort in the cabin. This study verifies the effectiveness of heat pump systems for dehumidification and heating and would be valuable to promote heat pump systems.

Pseudo-optimal discharge pressure analysis of transcritical CO2 electric vehicle heat pumps due to temperature glide

• A pseudo-optimal discharge pressure for electric vehicle heat pumps was proposed. • The principle of pseudo-optimal discharge pressure was explained. • Pseudo-optimal discharge pressure exists in subcritical and transcritical states. • The effects of conditions on pseudo-optimal discharge pressures were revealed. Performance improvement of electric vehicle heat pumps can enhance thermal comfort and reduce the power consumption of electric vehicles, hence stimulating their development. In this paper, the cyclic characteristics of an electric vehicle heat pump were studied under different operating modes and working conditions. Different from the optimal discharge pressure of conventional CO 2 systems which was determined by the variation gradient characteristics of the transcritical isotherm, the discharge pressure of electric vehicle heat pumps at the peak COP value was defined as a pseudo-optimal discharge pressure and was determined by the obvious temperature glide at the outlet of the gas cooler. This pseudo-optimal discharge pressure existed at both transcritical and subcritical states. The difference in the pseudo-optimal discharge pressure between the subcritical or transcritical states was first evaluated. Then an in-depth analysis of the influence of key parameters on the pseudo-optimal discharge pressure was studied to develop an accurate prediction method since the traditional prediction methods were not applicable. The results showed that pseudo-optimal discharge pressure increased with the ambient temperature, inlet air temperature, and supply air temperature. This study provides valuable information for the comprehensive performance optimization of an electric vehicle thermal management system.

Operational and embodied emissions associated with urban neighbourhood densification strategies

Urban densification increases the number of people living in urban areas and is hypothesized to be a more efficient use of available land than urban sprawl. The objective of this study was to quantify the operational and embodied emissions created as a result of densification. A ‘Business as usual’ and a ‘Concentrated’ densification strategy were investigated. When densifying at the neighbourhood level, existing buildings can either be replaced or extended to accommodate the additional inhabitants. The densification strategies were applied to two reference urban design neighbourhoods in Switzerland. The ‘Typical’ approach assumed that all the buildings were demolished and rebuilt and the ‘Preserve-existing’ approach involved the extension of existing buildings as much as possible. Construction material choice and modification of the built form were the sources of embodied emissions considered for each strategy. Urban building energy modelling was used to calculate the emissions incurred by heating the buildings and the embodied emissions were calculated using building standards. The operational performance was simulated assuming both a gas boiler and an electric heat pump to determine the influence of the heating system type on the operational emissions. This study found that savings of approximately 30% in embodied emissions can be achieved by extending the existing building stock rather than rebuilding. However, these savings represent a relatively small percentage of the total emissions incurred throughout a building’s lifetime and the savings further diminish in the concentrated densification strategies.

Exploring the challenges of residential space heating electrification in China: A case study in Jinan and Qingdao

De-carbonization actions, represented by the electrification of end-use energy sources, have been strongly promoted, while space heating in residential buildings is an important aspect. In this paper, Jinan and Qingdao in northern China are selected to explore the challenges that electrification of heating will bring. The electricity demand for heating of different types of buildings is simulated, with the assumption that all heating loads are provided by electric heat pumps. Then the comparison of heating electricity demand with current electricity consumption in various social sectors has been analyzed to investigate the impact of the newly added electrical load on the power grid. The annual dynamic power supply under the currently installed wind turbines and photovoltaic modules is calculated to explore the interrelationship between the power supply potential of the available renewable energy and the heating electricity demand. The results show that the implementation of heating electrification will bring a strong impact on the existing grid, with photovoltaic generation almost negligible during the heating period and wind generation severely affected by intermittency. In the future, the deployment of installed renewable energy needs to continue to be promoted, while the layout of energy storage facilities needs to be strengthened.

Life cycle climate performance (LCCP) evaluation model for electric vehicle heat pumps and emission reduction analysis of low-GWP refrigerants

<p indent="0mm">With the proposal of China’s carbon neutrality target and the official entry into force of the Kigali Amendment to the Montreal Protocol, the green and efficient development of the new energy vehicle heat pump is imperative, since China has the largest number of new energy vehicles in the world. The environmental-friendly heat pump with low global warming potential (GWP) is increasingly essential for the electric vehicle (EV) to save energy consumption and extend the driving range, it is beneficial to achieve the carbon neutrality from reducing both direct and indirect carbon emissions. The long-used R134a has a great climate impact due to its high GWP, researchers have been investigating heat pump systems with low-GWP refrigerants. Previously, the life cycle climate performance (LCCP) was a widely accepted metric to evaluate the carbon footprint of mobile air conditioning systems “from cradle to grave” for the classical engine vehicle, however, the new energy vehicle heat pump has significant differences from the mobile air conditioning systems, which makes the LCCP developed for MAC systems no longer applicable for the NEV heat pump system. Such LCCP analysis about EV heat pumps can hardly be found. To facilitate the EV industry and policymakers better understand the environmental impacts of those low-GWP refrigerants, this study provides a comprehensive LCCP analysis for the EV heat pumps based on the heat pump system bench test results, local climates (six cities: Beijing, Shanghai, Guangzhou, Phoenix, Fargo, and Chicago), local power supply characteristics, real-world driving patterns, vehicle cabin thermal sensation, and climate control load. Three low-GWP refrigerants, i.e., CO₂, binary blends of CO₂ and R41 (with GWP value of 49), M2 (R410A substitute with GWP value of 137), were compared against R410A and R134a. Results show that the system COPs in the energy consumption model are estimated within ±6.5%; In most regions, the heat pump can save 36%–69% of electricity for heating on electric vehicles compared to the conventional PTC heater system; The direct emissions depend on the refrigerant GWP and are almost unaffected by the climate. The indirect emissions are influenced by the climate, refrigerant type and the carbon intensity; among the indirect emissions, manufacturing and EOL disposal account for only 5% or so, while the major part is the emissions due to system operation; The R410A heat pump shows higher levels than R134a in both direct and indirect emissions, with 11%–36% increase in total; although M2 shows 2%–27% higher indirect emissions than R134a, it reduces 90% of the direct emissions. In general, it shows 3%–35% less total emissions compared to R134a for EV heat pump application; the direct emissions of the CO₂ heat pump can be neglected while the CO₂ system can reduce 7% of the indirect emissions only in cold climates such as Fargo. Thanks to its low direct emissions, the total LCCPs of the CO₂ heat pump are reduced by 6%–27% relative to R134a except in Shanghai (+20%); among the selected refrigerants, CO₂/R41 shows the lowest LCCP, reducing 5%–42% of total emissions relative to R134a in various climates, and 1%–21% less than the CO₂ system.

Evaluation of increased electricity production when cooling solar panels

A municipal housing company located in the south of Sweden has energy renovated several buildings with a total of 380 apartments to meet today’s energy standards. Several energy efficient technologies and solutions were implemented and the energy consumption for these buildings were lowered by 50%. One of the buildings functions as a demonstration building for innovative solutions such as low temperature district heating, waste water heat recovery, and solar photovoltaic and thermal (PVT) panels. The solar PVT panels are cooled down with the main purpose to increase the electricity production. The cooling medium for these panels is circulated through two bedrock boreholes to dissipate the collected heat. The heat from the boreholes is then used for an electric heat pump to produce heat to send to the local district heating company. The electricity produced is primarily used in the building. The objective of this paper is to assess the electricity production from real-life outdoor Photovoltaic-thermal (PVT) plant. The plant was installed on the roof top of an energy renovated multi-family apartment building located in the south of Sweden. The cooling of the panels were turned on and off to assess if the electricity production would increase or not. The electricity production did not increase when the cooling was applied. The temperature measuring equipment which was installed at the wrong position and was supposed to measure the temperature at the back of the PVT is needed to compare the efficiency of the PVT plant and draw further conclusions.

On the Importance of Grid Tariff Designs in Local Energy Markets

Local Energy Markets (LEMs) were recently proposed as a measure to coordinate an increasing amount of distributed energy resources on a distribution grid level. A variety of market models for LEMs are currently being discussed; however, a consistent analysis of various proposed grid tariff designs is missing. We address this gap by formulating a linear optimization-based market matching algorithm capable of modeling a variation of grid tariff designs. A comprehensive simulative study is performed for yearly simulations of a rural, semiurban, and urban grids in Germany, focusing on electric vehicles, heat pumps, battery storage, and photovoltaics in residential and commercial buildings. We compare energy-based grid tariffs with constant, topology-dependent and time-variable cost components and power-based tariffs to a benchmark case. The results show that grid tariffs with power fees show a significantly higher potential for the reduction of peak demand and feed-in (30–64%) than energy fee-based tariffs (8–49%). Additionally, we show that energy-based grid tariffs do not value the flexibility of assets such as electric vehicles compared to inflexible loads. A postprocessing of market results valuing the reduction of power peaks is proposed, enabling a compensation for the usage of asset flexibility.

Synergistic development of heating system decarbonization transition and large-scale renewable energy penetration: A case study of Beijing

In response to climate change, China has set the target to achieve carbon neutrality by 2060. The large-scale development of renewable energy and the decarbonization transition of the heating system are crucial for achieving this target. Is there a synergistic effect between the heating system's decarbonization transition and the use of large-scale renewable energy sources? What effect does this synergistic development have on the CO₂ emissions and the economic costs of an energy system? This paper conducts a case study of Beijing, China, and designs three technical path scenarios for heating system decarbonization transition in the future, namely, business as usual scenario where existing policies and regulations are applied, the electricity substitution scenario where the traditional fossil fuel heating system is replaced by electric heat pump, and the synergistic development scenario where the existing thermal power units are retrofitted to replace the consumption of fossil fuels with renewable energy sources. Using the EnergyPLAN model, the hourly operation of Beijing's power and heating systems under the three scenarios are simulated. The research results are: Firstly, the proportion of local renewable energy will be over 70% in all three scenarios, and in the synergistic development scenario, the electricity and heating demand can be met by 100% renewable energy, reducing CO₂ emissions resulted from fossil fuel combustion; secondly, in view of the real-time match of power supply and demand in the power system, at times renewable energy supply would exceed demand. The rational use of the surplus renewable energy can promote further the synergistic development of decarbonization transition of heating system and renewable energy, reducing the primary energy consumption and CO₂ emissions by over 16% and 28% respectively in the future heating system; Thirdly to improve the economic benefit of a synergistic electric power and heating system, focus should be on the reduction of infrastructure construction cost rather than the reduction of fuel consumption. The proposed method can be extended to regional energy systems with more energy sectors, and can be used to formulate decarbonization transition schemes for industry, agriculture, etc.

Characterizing air source heat pump market segments: A Canadian case study

Electric air source heat pumps (ASHPs) appear to be a key technology for decarbonizing space heating in existing residential buildings, yet their current market share in much of North America remains low. To explore how the potential future ASHP market may differ from the present one, we use a subset of data from the Canadian Home Heating Survey (n = 461) to provide a comprehensive characterization of three market segments of British Columbian homeowners: Pioneers (heat pump owners), Potential Early Mainstream buyers (homeowners currently willing to purchase an ASHP), and Late Mainstream buyers (homeowners currently unwilling to purchase an ASHP). We assess variable associations with market segments according to the Attitude-Behavior-Context theory, which posits that pro-environmental behavior is shaped by attitudinal, contextual, and socio-demographic factors. We also compare how market segmentation changes before and after respondents receive technical information on different home heating systems. Relative to Pioneers and the Potential Early Mainstream (PEM), we find that the Late Mainstream (LM) are generally lower income, lower educated, less environmentally- and technologically-oriented in their lifestyles, less open to change, less familiar with heat pumps and home energy efficiency, more negative in their perceptions about heat pumps, and less aware and supportive of policies aimed at reducing residential emissions. We also find that after respondents read technical information about home heating systems, approximately 10% of heat pump non-owners shift from the LM to the PEM; however, within the PEM, there is little growth in high willingness to adopt.

Life cycle assessment of tomato production for different production strategies in Norway

The availability of fresh vegetables grown in greenhouses under controlled conditions throughout the year has given rise to concerns about their impact on the environment. In high latitude countries such as Norway, greenhouse vegetable production requires large amounts of energy for heat and light, especially during the winter. The use of renewable energy such as hydroelectricity and its effect on the environment has not been well documented. Neither has the effect of different production strategies on the environment been studied to a large extent. We conducted a life cycle assessment (LCA) of greenhouse tomato production for mid-March to mid-October (seasonal production), 20th January to 20th November (extended seasonal) production, and year-round production including the processes from raw material extraction to farm gate. Three production seasons and six greenhouse designs were included, at one location in southwestern and one in northern Norway. The SimaPro software was used to calculate the environmental impact. Across the three production seasons, the lowest global warming (GW) potential (600 g CO2-eq per 1 kg tomatoes) was observed during year-round production in southwestern Norway for the design NDSFMLLED + LED, while the highest GW potential (3100 g CO2-eq per 1 kg tomatoes) was observed during seasonal production in northern Norway for the design NS. The choice of artificial lighting (HPS (High Pressure Sodium) or LED (Light Emitting Diodes)), heating system and the production season was found to have had a considerable effect on the environmental impact. Moreover, there was a significant reduction in most of the impact categories including GW potential, terrestrial acidification, and fossil resource scarcity from seasonal to year-round production. Overall, year-round production in southwestern Norway had the lowest environmental impact of the evaluated production types. Heating of the greenhouse using natural gas and electricity was the biggest contributor to most of the impact categories. The use of an electric heat pump and LED lights during extended seasonal and year-round production both decreased the environmental impact. However, while replacing natural gas with electricity resulted in decreased GW potential, it increased the ecotoxicity potential.

Heating performance of a hybrid power heat pump driven by gas engine and electrical motor

The gas engine-driven heat pump (GEHP) has a higher primary energy ratio (PER) than the electric heat pump (EHP) for heating, but has a lower PER than the EHP for cooling. To exploit the advantages of GEHP and EHP, a heat pump system where the compressor could be driven simultaneously by a gas engine and motor was proposed in the paper. An experimental platform was established to investigate the feasibility and performance of the HPHP system. In addition, numerical models were built for further performance analyses. The results indicate that: (1) Increases in the rotation speed of the compressor and engine power ratio lead to an increase in the total heating capacity. The rotation speed should be adjusted first to meet the required heating load, and then the engine power ratio can be adjusted to achieve better performance; (2) Engine power ratio changes the loads of the engine and motor, thus their efficiencies change, leading to different PERs of the HPHP system. Under different local gas and electricity prices, the engine power ratio can also be adjusted to reach a minimum operating cost; (3) For the case-studied commercial building in Beijing, the annual primary energy consumptions for HPHP, GEHP, and EHP are 94.2, 95.7, and 100.0 kWh/m2, respectively. In addition, HPHP saves operating costs by 17.5 % and 35.1 % compared to GEHP and EHP, respectively, with static payback periods of 2.45 and 1.47 years, even if it is only used for heating in winter.

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.