Characteristics Of Heat Pump Research Articles

Characterization and prediction of demand response potential of air conditioning systems integrated with chilled water storage

Chilled water storage offers a cost-effective and convenient solution for load flexibility of air-conditioning systems. However, its impacts on system flexibility and energy efficiency have not been comprehensively explored. In this paper, demand response (DR) potential delivered by chilled water storage was explored and predicted through both experimental and simulation studies. The initial experimental investigation focused on the DR potential at various cold charging and discharging proportions of chilled water storage. Subsequently, a virtual platform, validated through experimental data, was utilized to analyze load flexibility and energy efficiency of the system across different baseline loads, storage characteristics, and heat pump characteristics. Prediction models for DR potential in different cold charging and discharging scenarios were further developed based on the simulation results. The experimental and simulation results demonstrated effective load manage performance through adjusting charging and discharging proportions, even though the flexibility may sacrifice energy efficiency in cold discharging scenarios. In addition, the developed prediction models confirmed their feasibility with the coefficient of determination (R2) exceeding 0.80 in charging scenarios and 0.90 in discharging scenarios. The analysis also revealed significant benefits from storing supply water at lower temperatures and selecting heat pumps with partial-load efficiency curves characterized by higher Pearson Correlation Coefficients.

Large-scale monitoring of residential heat pump cycling using smart meter data

Heat pumps play an essential role in decarbonizing the building sector, but their electricity consumption can vary significantly across buildings. This variability is closely related to their cycling behavior (i.e., the frequency of on–off transitions), which is also an indicator for improper sizing and non-optimal settings and can affect a heat pump’s lifetime. Up to now it has been unclear which cycling behaviors are typical and atypical for heat pump operation in the field and importantly, there is a lack of methods to identify heat pumps that cycle atypically. Therefore, in this study we develop a method to monitor heat pumps with energy measurements delivered by common smart electricity meters, which also cover heat pumps without network connectivity. We show how smart meter data with 15-minute resolution can be used to extract key indicators about heat pump cycling and outline how atypical behavior can be detected after controlling for outdoor temperature. Our method is robust across different building characteristics and varying times of observation, does not require contextual information, and can be implemented with existing smart meter data, making it suitable for real-world applications. Analyzing 503 heat pumps in Swiss households over a period of 21 months, we further describe behavioral differences with respect to building and heat pump characteristics and study the relationship between heat pumps’ cycling behavior, energy efficiency, and appropriate sizing. Our results show that outliers in cycling behavior are more than twice as common for air-source heat pumps than for ground-source heat pumps.

Towards congestion management in distribution networks: a Dutch case study on increasing heat pump hosting capacity

The current high gas prices motivate end-users to replace their gas heating with electric heat pumps. This will likely cause frequent congestion issues in low-voltage (LV) distribution grids and slow down the heat pump adoption rate. To avoid or defer the expensive and complicated grid expansion, this study shares a solution approach of a Dutch Distribution System Operator (DSO) to enable the increasing adoption of heat pumps in existing dense housing areas. Data of the DSO and a local housing company have been combined to investigate the heat pump hosting capacity on a dense urban LV feeder, including realistic data of grid topology, load and heat dynamics, and practical operating characteristics of heat pumps. Our simulation compares two control strategies: (1) individual peak shaving and (2) central optimal power flow control. We show the central optimal power flow control with endusers' thermal comfort constraints and an objective function of minimizing losses can smoothen total grid loading and lead to flat voltage profiles. This allows the approach to be robust against baseload forecast errors, while the individual peak shaving is more prone to such errors. Moreover, by simulating the strategies on the worst-case scenarios where heat pumps are allocated to end-users at the end of the feeder, we determine the individual peak shaving strategy can slightly increase the heat pump hosting capacity from 49% where no control is imposed to 51%, while the central optimal power flow control allows 100% heat pump connections without causing grid congestion. Finally, recommendations to increase the heat pump hosting capacity are given based on simulation results.

Pumping up adoption: The role of policy awareness in explaining willingness to adopt heat pumps in Canada

Heat pumps are a key technology for decarbonising residential buildings, yet their current market share in Canada remains very low at approximately 5 %. To promote heat pump adoption, governments in Canada have introduced supportive policies such as purchase subsidies, and it is often assumed that increasing consumer awareness of such policies increases heat pump adoption. Using a survey of Canadian homeowners who do not own heat pumps (n = 3138), we assess: (1) levels of willingness to adopt air source and ground source heat pumps across Canada, (2) the effect of information provision on willingness to adopt heat pumps, (3) levels of heat pump policy awareness across Canada, (4) whether perceived technical characteristics of heat pumps can be categorized as functional or symbolic, and as private or societal, and (5) the role of policy awareness and other drivers in explaining willingness to adopt heat pumps. We find that a third of Canadian homeowners express willingness to adopt heat pumps. These homeowners are found predominantly within the Atlantic region and show higher levels of adoption willingness for air source rather than ground source heat pumps. Awareness of existing heat pump supportive policy is low, with only 5 % of respondents able to name any policies from memory. Awareness tends to be higher in British Columbia, and for heat pump subsidies and carbon taxes. Policy awareness without cues (i.e., being able to freely recall policies) is a positive predictor of willingness to adopt air source heat pumps only. Policy awareness with cues (i.e., when respondents were provided with a list of policies that served as a memory prompt) is not associated with willingness to adopt either type of heat pump. Other significant predictors include perceptions of heat pumps' functionality and their environmental benefits, having a technology-oriented lifestyle, having higher support for policies, and the financial and inconvenience costs during installation. Based on findings, insights into targeted policy designs to accelerate residential building decarbonisation are provided.

Potential of CO2 Emission Reduction via Application of Geothermal Heat Exchanger and Passive Cooling in Residential Sector under Polish Climatic Conditions

The article summarizes the results of the 25-year time horizon performance analysis of the ground source heat pump that serves as a heat source in a detached house in the climatic conditions that prevail in Wrocław, Poland. The main aim is to assess the potential of ground regeneration and reduction of CO2 emission by passive cooling application. The study adds value to similar research conducted worldwide for various conditions. The behavior of the lower source of the heat pump was simulated using EED software. The ground and borehole properties, heat pump characteristics, heating and cooling load, as well as the energy demand for domestic hot water preparation have been used as input data. Based on the brine temperatures for all analyzed cases including the ground with lower and higher values of conductivity and heat capacity, the borehole filler of inferior and superior thermal properties, and the passive cooling option turned on and off, the seasonal efficiencies of the heat pump have been calculated. The energy and emission savings calculations are based on the values obtained. The application of passive cooling reduces the brine temperature drop by 0.5 K to over 1.0 K in consecutive years in the analyzed cases and the thermal imbalance by 65.0% to 65.9%. Electric energy savings for heating and domestic hot water preparation reach 4.5%, but the greatest advantage of the system is the possibility of almost emission-free colling the living spaces which allows reducing around 33.7 GWh of electric energy and 1186–1830 kg of CO2 emission for cooling.

Investigation of Combined Heating and Cooling Systems with Short- and Long-Term Storages

Modern buildings in cold climates, like Norway, may have simultaneous heating and cooling demands. For these buildings, integrated heating and cooling systems with heat pumps, as well as short-term and long-term thermal storage, are promising solutions. Furthermore, combining this integrated system with renewables aids in the transition to future sustainable building energy systems. However, cost-effectively designing and operating such a complicated system is challenging and rarely addressed. Therefore, this research proposed an integrated heating and cooling system that incorporated a short-term water tank and a long-term borehole thermal storage. Meanwhile, three operating modes: heating, cooling, and free cooling were defined based on different heating and cooling load conditions. A detailed system model was developed in MATLAB using heat pump manufacture data as well as simulated and measured building loads. Following that, sensitivity studies were performed to investigate the impacts of ground properties, thermal storage size, setpoint temperature, heat pump characteristics, and load conditions. The findings identified the crucial factors that influence the system’s overall energy efficiency and the functioning of the key system components. Particularly, it revealed that low cooling to heating ratios caused an imbalance in charging and discharging, further reducing the ground temperature and degrading the heat pump’s performance.

Heat production model by a heat pump

The article deals with the possibility of determining the consumption of electrical energy by heat pumps. In the course of research experimental measurements have been made and energy characteristics of heat pump have been determined. The parameters of the heat pump, which essentially influence the degree of heat production, are determined. As a result of statistical processing of the experimental data the regression model of heat production by the heat pump is received.

Investigation of Heat Pump Efficiency in Baltic States Using TRNSYS Simulation Tool

Abstract A heat pump is one of the most popular energy transformation devices to provide the building with the necessary heating and cooling energy during the cold and warm seasons. Air source heat pumps (ASHP) in building heating and/or hot water systems are becoming more and more attractive these days because they can use renewable energy as an energy source instead of fossil fuels and thus contribute to the fight against climate change. By using an evaporator heat exchanger, ASHP takes the low-potential heat from the ambient air and transforms it into higher-potential heat for building heating and/or hot water preparation. The main problem with this type of energy transformer is the freezing of the evaporator at high outdoor humidity and a temperature close to 0° C when the condensed moisture of the ambient turns to frost on the surface of the evaporator heat exchanger. This phenomenon significantly reduces the efficiency (COP) of the ASHP. Thus, its performance strongly depends on the climatic conditions of the environment in which it operates. This study presents a numerical model of the heat pump under investigation developed with the TRNSYS software. The type of heat pump used in TRNSYS has been adjusted according to the heat pump characteristics provided by the manufacturer. The validated model is used to model the heating system of a building in the three Baltic States. Modeling results under different climatic conditions are presented.

Improving the energy flexibility of single-family homes through adjustments to envelope and heat pump parameters

With the increase of fluctuating renewable resources both on the grid and locally on buildings, a need arises for buildings to be flexible such that their energy demand can be modified to match energy generation. This study aims to characterize key approaches to increase the flexibility of a single-family home subject to a number of climate conditions. The home is modeled in TRNSYS in 5 climates, and building thermal mass, heat pump characteristics, and water heating setpoints are adjusted to assess the impact of each on the building's flexibility. The key metric used to assess flexibility is the cumulative absolute residual load over a year, where the residual load is defined as the difference between the average hourly demand of electricity and the average hourly available electricity. A control scheme is employed to implement demand response, but overall energy demand and thermal comfort are also considered throughout the year to assess effectiveness of the demand response approach. Results presented on 21 variations to the base house show the benefit of thermal mass in maintaining thermal comfort while changing thermostat setpoints and demonstrate the benefit of variable speed heat pumps for meeting available electricity supply. In the best case, a 36% decrease in residual load over the year is found for a simulation in Gaithersburg, MD compared to the base case. Results from this work suggest best approaches to take when developing new housing stock if consideration is needed for how well the buildings can respond to fluctuations in energy generation from intermittent sources such as wind and solar.

Energy Cooperation Optimization in Residential Microgrid with Virtual Storage Technology

The power balance of the tie-line is crucial to the stable operation of a community microgrid. This paper presents a power fluctuation smoothing method of the microgrid tie-line based on virtual energy storage technology. Firstly, the structure characteristics and the energy coupling mode of the combined heat and power system is systematically analyzed. Considering the operating characteristics of heat pumps, micro gas turbines, and buildings’ heat storage characteristics, a virtual energy storage model is established. Secondly, the target power of the tie-line is determined with the storage state indexes into consideration. Subsequently, a power allocation strategy which takes into account the correction of equipment state mapping set is proposed to allocate the tie-line power fluctuations to heat pumps, micro gas turbines, and supercapacitors. Simulation results show this method can realize the coupling coordination between heat and power energy and ensure the smoothing effect of the power fluctuations. Meanwhile, the control flexibility of the combined heat and power system can be enhanced, and the microgrid’s operating economy can be improved.

Dynamic performance characteristics of R410A heat pump with consideration of energy efficiency and thermal comfort at various compressor frequencies and outdoor fan speeds

Advanced control strategies in heat pumps must be developed to achieve a high energy efficiency in real time while ensuring thermal comfort. The objective of this study was to investigate the dynamic performance characteristics of a heat pump with consideration of the energy efficiency and thermal comfort. A dynamic simulation model for a heat pump was developed and validated using experimental data. The dynamic characteristics of the heat pump were analyzed at various outdoor fan speeds and compressor frequencies. The optimum outdoor fan speed and compressor frequency were determined to be 800 rpm and 50 Hz, respectively, for achieving the maximum energy efficiency. When the heat pump was operated to satisfy thermal comfort under the optimized conditions, the cooling time and energy consumption decreased by 56.5% and 74.8%, respectively, compared with the baseline cycle.

Air-water heat pump modelling for residential heating and domestic hot water in Chile

In Chile, household heating demands are mainly provided by wood stoves and domestic hot water by gas water heater. This presents two drawbacks, the use of wood stoves for heating is responsible of severe pollution problems during winter period and another drawback is associated to the high price of the gas. To mitigate these problems, it is proposed to analyse the use of heat pumps for both heating and domestic hot water. The first step for this analysis is to determine the seasonal performance of the heat pump, which depends, among others, on the building location, building characteristics and heat pump characteristics. In this study the performance of a four occupants household located at Concepción and Santiago are considered. The heating demand is determined by using the software TRNSYS, by obtaining an annual heating demand that varies between 5003 kWh and 8788 kWh for Concepción and between 4388 kWh and 7883 kWh for Santiago. The domestic hot water demand is determined from a typical consumption profile, with an annual energy demand of 3721 kWh and 3541 kWh for Concepción and Santiago respectively. These profiles are used as inputs to the heat pump model by developing an hourly simulation. The heat pump is modelled by using a modular approach decomposed in three individual models for the following components: compressor, condenser and evaporator. It is assumed that the compressor is regulated with an ON/OFF control. The system SPF varies between 2,54 and 2,60 for the six cases analysed in this study. There is no significant difference in the SPF in both cities, which is attributed to the ambient conditions, which are in average very similar.

The Means to Improve Water Treatment and to Enhance Power Engineering Performance of the Water Source Heat Pump

The subject matter of the paper is related to scientific-and-theoretical basis of power engineering characteristics of heat pump directly depending on the quality of treated water for reliable and uninterrupted operation of heat pump evaporator and compressor. On the basis of experimental data, energy parameters of the heat pump are calculated. The method of the combined technology of the heat pump “water – air” operation is considеred, the efficiency of which is based on the preliminary improvement of the quality of water softened with the use of a membrane ultrafiltration unit. This solution made it possible to reduce the load on the filters and to exclude the use of chemical reagents used in the classical schemes of water heating facilities. In order to improve the operation of the heat pump compressor, a method based on altering the speed of rotation of the shaft by means of electronic microprocessor devices has been proposed. To regulate the compressor performance, a frequency converter with a wide range of alternating current frequency is used. The intervals of alteration of frequency of the alternating current corresponding to energy-efficient values of coefficient of transformation of energy of the heat pump are investigated. The values of the energy conversion coefficient of the heat pump obtained in the course of experiments and determined by calculation are consistent within the experimental errors with the regulation of the compressor performance. The suggested experimental device made it possible to determine the dependence of the main characteristics of the unit of the heat pump unit on the number of revolutions of the compressor and to find out an effective range of its control (50–180 %). The development of advanced technologies for natural water treatment under conditions of increased anthropogenic loads on natural water sources is a priority one among the fundamental and applied research in the field of water treatment.

Research of waste heat energy efficiency for absorption heat pump recycling thermal power plant circulating water

The waste heat energy efficiency for absorption heat pump recycling thermal power plant circulating water has been analyzed. After the operation of heat pump, the influences on power generation and heat generation of unit were taken into account. In the light of the characteristics of heat pump in different operation stages, the energy efficiency of heat pump was evaluated comprehensively on both sides of benefits belonging to electricity and benefits belonging to heat, which adopted the method of contrast test. Thus, the reference of energy efficiency for same type projects was provided.

Principle and Characteristics of Heat Pump Air Conditioning System

The heat pump technology is paid more and more attention in building energy saving. By analyzing the principle and characteristics of air source heat pump, ground source heat pump and water source heat pump, this paper points out the problem of developing heat pump technology in China at present and its future prospects.

Principle and Characteristics of Heat Pump Air Conditioning System

More and more attention has been paid to the heat pump technology in building energy efficiency. Based on the analysis of the principles and characteristics of air source heat pump, ground source heat pump and water source heat pump, this paper points out the problems and future in the development of heat pump technology in China.

Perspective Performance Evaluation Technique for a Cascade Heat Pump Plant Functions at Low Temperature Heat Source

The present investigation deals with the performance assessment of Cascade heat pump plants. The overall power consumption for a Cascade system for typical heat pump characteristics was studied. Four environment friendly refrigerant pairs R717/R134a, R410A/R134a, R407C/R134a, and R717/R600a were investigated at low temperature cycle (LT) evaporator and high temperature cycle (HT) condenser temperatures of (-15 to -4)°C and (70)°C respectively. A preliminary heat pump plant is suggested to produce (500) kW heat output load as hot water demand at (65)°C with (25)°C temperature lift and a proper circulation rate. The investigation was carried out at cascade heat exchanger intermediate temperature (IT) of (33)°C and (35)°C. Sea water at (7)°C was used as a sustainable low temperature heat source and (30%) ethylene glycol-water brine at temperature of (5)°C as a thermal fluid heat carrier at the LT cycle evaporator. The evaluation of the thermal performance of the refrigerant pairs was based on a fixed heat pump extraction load at the LT cycle. The heat pump heating coefficient of performance (COP) revealed an increase fell within the range of (5-7.5)% higher than that of the plant heating COP value for the studied refrigerant pairs at the whole investigated operating conditions range. The higher IT exhibited the highest heat pump and plant heating COP than those at the lower value. R717/R600a showed the highest heating COP, lower power consumption and lower global warming potential (GWP) among other investigated refrigerant pairs. The power consumed by auxiliary pumps to circulate thermal fluid heat carriers through a heat pump may account to (4-4.5)% and (2-3)% of the extracted and output heating loads respectively, higher values could be expected for real plant. Two polynomial correlations for the assessment of the pumping power in terms of the extracted and output heating loads were derived from the present work.

Use of heat pumps in turbogenerator hydrogen cooling systems at thermal power plant

The possible increase in heat power generation efficiency was evaluated through this paper via installation of heat pumps for cooling hydrogen in generator of steam turbine.Using the heat pumps, the biggest part of waste heat from turbogenerator hydrogen cooling systems can be transferred to heat supply system. They are used for heat supply in-house load of a power plant or for any other goal of heat supply as well.All calculations were made for thermal power plant at the branch “Nevsky” “TGC-1” company – CHP-21. The analysis was made for heat pumps with heat capacities of 2 MW and 3 MW. The application of such analysis on CHP was applied by the method of detailed settlement estimation of the impact on CHP operating mode with synchronous calculation of characteristics of heat pump. The analysis was made for different operating mode of CHP. A low potential heat source is the water from hydrogen cooling systems of steam turbine generator.The use of heat pumps for steam turbine generator hydrogen cooling system waste heat salvaging is innovation solution to increase TPP cost-performance ratio. On implementing cycle arrangement with heat pump used for sanitary and service makeup water warming, fuel saving is up to 700 toe/year while heat pump system specified heat power is 3 MW.

Performance of a swimming pool heating system by utilizing waste energy rejected from an ice rink with an energy storage tank

This study deals with determining the long period performance of a swimming pool heating system by utilizing waste heat energy that is rejected from a chiller unit of ice rink and subsequently stored in an underground thermal energy storage (TES) tank. The system consists of an ice rink, a swimming pool, a spherical underground TES tank, a chiller and a heat pump. The ice rink and the swimming pool are both enclosed and located in Gaziantep, Turkey. An analytical model was developed to obtain the performance of the system using Duhamel’s superposition and similarity transformation techniques. A computational model written in MATLAB program based on the transient heat transfer is used to obtain the annual variation of the ice rink and the swimming pool energy requirements, the water temperature in the TES tank, COP, and optimum ice rink size depending on the different ground, TES tank, chiller, and heat pump characteristics. The results obtained from the analysis indicate that 6–7years’ operational time span is necessary to obtain the annual periodic operation condition. In addition, an ice rink with a size of 475m2 gives the optimum performance of the system with a semi-Olympic size swimming pool (625m2).

Detailed simulation of electrical demands due to nationwide adoption of heat pumps, taking account of renewable generation and mitigation

This study quantifies the increase in the peak power demand, net of non-dispatchable generation, that may be required by widespread adoption of heat pumps. Electrification of heating could reduce emissions but also cause a challenging increase in peak power demand. This study expands on previous studies by quantifying the increase in greater detail; considering a wider range of scenarios, the characteristics of heat pumps and the interaction between wind generation and demand side management (DSM). A model was developed with dynamic simulations of individual heat pumps and dwellings. The increase in peak net-demand is highly sensitive to assumptions regarding the heat pumps, their installation, building fabric and the characteristics of the grid. If 80% of dwellings in the UK use heat pumps, peak net-demand could increase by around 100% (54 GW) but this increase could be mitigated to 30% (16 GW) by favourable conditions. DSM could reduce this increase to 20%, or 15% if used with extensive thermal storage. If 60% of dwellings use heat pumps, the increase in peak net-demand could be as low as 5.5 GW. High-performance heat pumps, appropriate installation and better insulated dwellings could make the increase in peak net-demand due to the electrification of heating more manageable.