Assessing climate adaptability and low-carbon efficiency of air source heat pumps in China's diverse climates

Objective. Over the past decades, heat pumps have gained great popularity due to their advantages in energy efficiency and environmental friendliness, becoming one of the most attractive alternatives to replace traditional heating systems running on fossil fuels. Heat pump efficiency is a decisive factor that should be taken into account when selecting and optimizing a heat pump system. The aim of the study was to evaluate the efficiency of air source heat pumps of the air-to-water system in the climatic conditions typical of the regions of the Central Federal District. Method. To evaluate the efficiency of air source heat pumps, a mathematical model is used that takes into account the multifactorial nature of the process under study. Result. To adequately compare the obtained research results with the passport performance indicators, the transformation coefficient (COP) was used, showing the ratio of the energy received to the expended work. As a result, the method of heating rooms with an air source heat pump with a combined operation mode was recognized as more preferable. Conclusion. Currently, the potential of heat pumps in the field of energy saving and CO2 emission reduction remains largely untapped, which sets the vector for further research.

To develop the laboratory of renewable energy sources in Miekinia, a new stand with a heat pump was created. The main aim of this stand is to increase the range of research in the Laboratory. This stand consists of: a heat pump module, a module to simulate the parameters of the heat source and heat sink, a module to display and register data and a remote control. This creates opportunities for research about the efficiency of heat pumps in reference to present standard PN EN 14511 and previous standard PN EN 255. The data allows us to define the impact of the methodology described in the standards on the coefficient of performance. This stand is able to calculate the coefficient of performance according to set parameters of work, like temperature of heat source, temperature of heat sink or difference between inlet temperature and outlet temperature on the heat sink side. There is also research about the effect of the superheating of refrigerant on the efficiency of heat pumps. All of the research with this stand is intended to examine the efficiency of heat pumps. This stand was also made for didactic purposes. It has the possibility to show the following, how the heat pump works, how the refrigerant circulates inside the heat pump, and what happened with the refrigerant in elements of a heat pump like a compressor, evaporator, condenser, expansion valve. There is also the possibility to show the dependence between the coefficient of efficiency and the temperature of the heat source or heat sink.

In order to improve defrosting efficiency of air source heat pump, it is crucial to reveal the evaporation characteristics of defrosting residual droplet on fin surface and find ways to enhance the evaporation performance. In this work, the evaporation of defrosting residual droplet is investigated experimentally under different influence factors according to the defrosting condition of air source heat pump. Meanwhile, the availability of the evaporation performance enhanced by electric field is evaluated. Experimental results show that the droplet evaporates on superhydrophobic fin surface at constant contact angle and mixed modes, without the pinning stage; while it is constant contact diameter and mixed modes on bare fin surface. As the fin surface temperature increases or the droplet size decreases, the evaporation time of the droplet becomes shorter. The droplet evaporation time is 25.4% of that without electric field on bare fin surface, when the droplet volume is 1 ?L and the electric intensity is 15 kV/cm. Interestingly, the electric field forces the droplet on superhydrophobic fin surface to jump, and it is no longer necessary to remove the droplet by evaporation. In a word, applied electric field can enhance the droplet evaporation, which will save defrosting energy consumption and improve defrosting efficiency of air source heat pump.

The frost restraining effect of solar air collector applied to air source heat pump

Emergy analysis and optimization for a solar-driven heating and cooling system integrated with air source heat pump in the ultra-low energy building

Flat tube heat exchangers: Experimental analysis of frosting and water retention

Due to the low efficiency and frosting of the air source heat pump (ASHP) in extreme cold climates, the use of existing solar water heaters or dedicated solar collectors as auxiliary heat sources can further improve the overall operating efficiency of ASHPs. Based on the case study of a typical rural building in Shandong, the simulation models of the solar-air source heat pump (SASHP) systems connected respectively in series and in parallel have been established under the TRNSYS platform. The operating performance and the solar fraction of the two systems have been simulated under different conditions. The results show that the performance of the parallel SASHP system is higher than that of the series SASHP system. The research results can provide certain guideline for the clean heating in rural areas of Shandong province in China.

In order to understand the solar heat pump heating system, a phase-change storage solar heat pump heating system based on cloud computing is proposed. This paper first introduces the solar heat pump as a phase change energy storage that can change four types of heat depending on the weather conditions and significantly reduce the energy consumption of the system. Second, through the special design of the energy storage capacitor, in addition adjusting the energy distribution of the solar heat pump system, it can also improve the reliability of supply and demand between the solar heat pump system and the building heating system, improve the level of solar energy consumption, but also improve the low temperature of the pump milk temperature, and improve the solar heat up quickly to achieve the goal of improving the overall performance of the heat pump. Finally, this paper takes an urban ?electric coal? house as a research object to investigate the hot air efficiency of solar heat pumps. This paper analyzes the daytime solar heat pump mode, the nighttime energy storage mode under extreme conditions, and the air source heat pump mode. And shows the research results that the solar heat pump has good heating efficiency and the highest solar COP. Will be heat pump is 5.28 solar energy average heat pump COP is 2.13. In very bad weather, solar heat pumps work better.

Energy geostructures are a cost-effective solution for low enthalpy geothermal installations. Heat exchanger pipes are attached to the reinforcing cages of geotechnical structures to combine structural and geothermal roles. However, the installation of a group of multiple energy structures, such as a pile group, can lead to a heat cluster effect, which tends to decrease the efficiency of the heat pump (COP factor). This phenomenon is amplified by the number of grouped energy geostructures. However, energy geostructures are often installed in areas with groundwater flow. This induces a thermal washing effect, which decreases the risk of multi-year thermal shifts and preserves heat pump efficiency. In this paper, we evaluate the heat cluster effect in a group of piles, its influence on heat pump COP, the benefit of thermal washing due to underground water flow, and the effect of various seasonal scenarios. For this purpose, we present and use a specific numerical process that allows for modeling energy geostructure installations and interactions between groundwater flow models and thermal models. The heat pump COP is then estimated according to variable heat load, which depends on soil temperature.

Performance analysis of PEMFC-assisted renewable energy source heat pumps as a novel active system for plus energy buildings

A general procedure is presented for estimating the seasonal performance of solar-assisted heat pumps with refrigerant-filled collectors. The procedure accounts for variations in collector design and orientation and also for heat pump capacity and efficiency. The results from this design procedure for space heating applications are compared against those for both conventional heat pumps and liquid solar systems. The effects of collector area and design, heat pump size and degradation due to cycling, and energy storage are discussed. For space heating, uncovered collector heat pump systems have better performance than both conventional air-source heat pumps and covered collector heat pump systems over a wide range of collector areas. The cooling performance of a collector heat pump system is inferior to that of conventional heat pumps.

The article is performing a comparative exergy analysis of a thermoelectric heat pump and a vapour compression heat pump, operating in the same conditions, from heat source temperature point of view. The COP of vapour compression heat pump was found to be 3.02 compared to 1.349 for the thermoelectric heat pump for 60 ℃ temperature lift. For the same temperature lift, corresponding to the increase in the temperature of the heat source from 5 ℃ to 65 ℃ required for the delivery of heat for household purposes, exergy efficiency of vapour compression heat pump is 59.44% compared to 23.90% for the thermoelectric heat pump, while the energy needed to operate the thermoelectrical heat pump is 20.76 kW compared to 9.29 kW for vapour compression heat pump.

This research work aims at a multinational study in Europe of the emissions and energy costs generated by the operation of low enthalpy geothermal systems, with heat pumps fed by different energy sources. From an economic point of view, natural gas and biogas prices are, usually, lower than electricity ones. So it may be advantageous to use these energy sources to feed the heat pumps instead of electricity. From the environmental point of view, it is intended to highlight the fact that under certain conditions of electricity production (electricity mix), more CO2 emissions are produced by electricity consumption than using other a priori less “clean” energy sources such as natural gas. To establish the countries where each of the different heat pumps may be more cost-efficient and environmentally friendly, data from multi-source geospatial databases have been collected and analyzed. The results show that in the majority of cases, the electric heat pump is the most recommendable solution. However, there are some geographic locations (such as Poland and Estonia), where the gas engine heat pump may be a better alternative.

Energy consumption around the world is growing continuously and more rapidly. There are three ways to solve the energy problem in the future: the use of new and more efficient use of existing energy sources and the rational use of extracted energy. Modern technologies for developing fuel deposits allow extracting on average no more than 40 percent of the subsurface content, the level of science and technology does not allow achieving a greater level of its extraction with sufficient economic effect. The most cost-effective, simple and feasible way to efficiently use the extracted energy is to utilize the waste heat. The article considers the advantages and possibility of using thermoelectric heat pumps based on Peltier elements. (Research purpose) The research purpose is in justifying the effectiveness of using semiconductor heat pumps in thermal technological processes at livestock facilities. (Materials and methods) During the study, the authors used methods of system analysis and synthesis of existing knowledge in the field of research on the development of thermoelectric heat pumps. (Results and discussion) The article presents the adjusted methodology for calculating the efficiency of thermoelectric heat pumps. The heat energy withdrawn by the hot circuit, and directed to heating the air, exceeds the energy consumed from the electrical network. (Conclusions) The utilization coefficient in most modern thermoelectric installations is at the level of 3-5, which means that one kilowatt-hour of electrical energy consumed produces 3-5 times more thermal energy. Heat pumps are efficient because they allow to use renewable energy, and therefore they are economically feasible.

In cold regions, due o the impact of climatic conditions, the heat load in winter and the cooling load in summer are unbalanced. In the long-term operation of the ground-source heat pump (GSHP), the soil heat imbalance phenomenon has still not been successfully solved. Therefore, this study took the GSHP of a public building in the cold area of northern China as the research object. Based on the unit performance data of the system over 8 years and the measured data of the soil temperature field, the long-term operation efficiency of the GSHP in the cold region and the variation law of the soil temperature field were explored. In order to further study the problem of soil heat imbalance, the effect of heat exchange hole groups at different intervals on the underground soil thermal environment after 30 years of operation in the system was simulated, and the optimization scheme of heat exchange hole spacing was proposed. The research results support the improvement and optimization of GSHP design and construction, and have important practical significance for the popularization of GSHPs in cold regions.