Improving a heat supply system by increasing the efficiency of the heat pump unit

The reliability and efficiency of the operation of district heating systems is largely determined by the efficiency of preparation of heating network water. In open heat supply systems, make-up water, among other things, compensates for the water intake in hot water supply systems. A number of technologies have been developed that increase the efficiency of an open heat supply system by reducing the water consumption in the supply pipeline of the heating network, increasing the operating time of the heat pump, and increasing the specific generation of electricity for heat consumption at the CHP plant due to additional cooling of the network water in the return pipe of the heating network.

Prospects for the development of geothermal energy supply

The paper addresses methodological and technological issues of building environmentally friendly and efficient energy supply based on geothermal energy sources. Geothermal potential in the world, accentuating that in Russia (areas of the Baikal natural territory) and Mongolia, is analyzed considering the possibility of its implementation in the thermal power industry. Geothermal areas of Central Mongolia are characterized by increased heat flows and occurrences of thermal waters. The most promising thermal spring occurrences are the Shivert, Shargalzhuut, Tsenkher, Otgontenger, and Khuzhirt, to name some of them. Currently, the thermal energy potential of the Khangai arched uplift in Central Mongolia is employed to heat industrial, agricultural, and civil facilities. There are also plans to consider the possibility of large-scale employment of thermal waters of the region for electricity generation. An example of using geothermal waters for electricity generation is given, and the possibility of establishing a heating system in the city of Tsetserleg based on a geothermal heat pump unit with a wind power plant is assessed.

Study on the Long-Term Performance and Efficiency of Single-Well Circulation Coupled Groundwater Heat Pump System Based on Field Test

Although buildings are often heated and cooled by single-well circulation coupled groundwater heat pump systems, few studies have evaluated the long-term performance of these systems. Therefore, the present study investigated the performance of these systems by analyzing the efficiency and energy consumption using 4 years of operating data. The results indicate that the coefficient of performance (COP) of the system gradually decreases because of thermal breakthrough or an accumulation of cold. In addition, the sealing clapboards could effectively slow down thermal breakthrough. In addition, compared with the heating period, the COP of the heat pump unit (HPU) and system increases, and its energy consumption decreases in the cooling period. It was also found that partial heat loss occurs when water from the single-well circulation outlet penetrates the main pipeline. Moreover, the heat-exchange efficiency of a single HPU exceeds that of multiple HPUs, and the COP of a HPU decreases during operation with increasing indoor temperature. Accordingly, we improved the performance of system by increasing the underground heat storage. Herein, we focus on optimizing the system design during long-term operation, which includes taking steps such as lengthening the sealing clapboards, using insulated pipes, discharging the remaining water and adding intelligent control devices.

Fault Detection Algorithm for Multiple-Simultaneous Refrigerant Charge and Secondary Fluid Flow Rate Faults in Heat Pumps

The detection and diagnosis of faults is becoming necessary in ensuring energy savings in heat pump units. Faults can exist independently or simultaneously in heat pumps at the refrigerant side and secondary fluid flow loops. In this work, we discuss the effects that simultaneous refrigerant charge faults and faults associated with the flow rate of secondary fluids have on the performance of a heat pump operating in summer season and we developed a correlation to detect and diagnose these faults using multiple linear regression. The faults considered include simultaneous refrigerant charge and indoor heat exchanger secondary fluid flow rate faults (IFRFs), simultaneous refrigerant charge and outdoor heat exchanger secondary fluid flow rate faults (OFRFs) and simultaneous refrigerant charge, IFRF and OFRF. The occurrence of simultaneous refrigerant charge fault, IFRF and OFRF caused up to a 5.7% and 8% decrease in cooling capacity compared to simultaneous refrigerant charge and indoor heat exchanger secondary fluid flow rate faults, and simultaneous refrigerant charge and outdoor heat exchanger secondary fluid flow rate faults, respectively. Simultaneous refrigerant charge fault, IFRF and OFRF resulted in up to an 11.6% and 5.9% decrease in COP of the heat pump unit compared to simultaneous refrigerant charge fault and IFRF, and simultaneous refrigerant charge fault and OFRF, respectively. The developed FDD correlations accurately predicted the simultaneous refrigerant charge and faults in the flow rate of the secondary fluid within an error margin of 7.7%.

A Prototype Of Propane Refrigerant Based ASHP With Heat Recovery Ventilation (HRV) System

In recent years, an increased focus has been given to replacing high Global Warming Potential (GWP) refrigerants with relatively low GWP alternatives. Energy efficiency, carbon reduction and HFC phase-down will push the heat pump market towards natural refrigerants. Propane (R-290) is a type of hydrocarbon refrigerant with zero ozone depletion potential and very low GWP (< 4). R-290 is a pure refrigerant and has excellent thermodynamic properties. The research presented in this project is a study of the refrigerant side of an ASHP to analyze the thermodynamic performance of the propane refrigerant under different operating conditions. For this purpose, a test rig was designed and constructed in a single packaged air source heat pump unit. In addition, the air side of the tested heat pump was designed for energy recovery in cooling and heating modes. The compactness of the system and installation of air dampers allows its placement for coupling to the building renewable air sources, such as a building integrated photovoltaic/thermal (BIPV/T) system.

A Prototype Of Propane Refrigerant Based ASHP With Heat Recovery Ventilation (HRV) System

In recent years, an increased focus has been given to replacing high Global Warming Potential (GWP) refrigerants with relatively low GWP alternatives. Energy efficiency, carbon reduction and HFC phase-down will push the heat pump market towards natural refrigerants. Propane (R-290) is a type of hydrocarbon refrigerant with zero ozone depletion potential and very low GWP (< 4). R-290 is a pure refrigerant and has excellent thermodynamic properties. The research presented in this project is a study of the refrigerant side of an ASHP to analyze the thermodynamic performance of the propane refrigerant under different operating conditions. For this purpose, a test rig was designed and constructed in a single packaged air source heat pump unit. In addition, the air side of the tested heat pump was designed for energy recovery in cooling and heating modes. The compactness of the system and installation of air dampers allows its placement for coupling to the building renewable air sources, such as a building integrated photovoltaic/thermal (BIPV/T) system.

Evaluation of the coefficient of performance of an air source heat pump unit and an air to water heat pump

Air source heat pump (ASHP) water heaters are efficient devices for sanitary hot water heating. The coefficient of performance (COP) of the air to water heat pump (AWHP) is constantly lower than that of the corresponding ASHP unit. The study focused on determining the COP of both the ASHP unit and the AWHP. This was achieved by the implementation of both experimental and simulation methods, with the help of a data acquisition system and the REFPROP software. The system comprised of a 1.2 kW split type ASHP unit and a 150 L high pressure geyser. A power meter, flow meters, temperature sensors, pressure sensors, ambient temperature and relative humidity sensor were installed at precise locations on the split type AWHP. Controlled volumes of 150, 50 and 100 L were drawn off from the AWHP during the morning, afternoon and evening for a year. The average COP for the summer and winter, in terms of the input electrical and output thermal energies of the AWHP were 3.02 and 2.30. The COPs of the ASHP unit, in terms of the change in the enthalpies of the refrigerant at the inlet and the outlet of the condenser and the evaporator, were 3.52 and 2.65 respectively. The study showed that the difference between the COP of the ASHP unit and that of the AWHP could be ascribed to the electrical energy consumed by the fan and the water circulation pump during the vapour compression refrigeration cycles. The work provides an energy optimisation opportunity to the manufacturers of this technology, helping to enhance the efficiency and COP of ASHP water heaters. Highlights The COPt of the ASHP unit was higher than the COPe of the AWHP. The COPe of the AWHP was the ratio of the input electrical energy consumed and the output thermal energy gained by the stored water. The COPt of the ASHP unit was enthalpies-dependent and a function of inlet and outlet enthalpies of the evaporator and condenser. The inlet and outlet refrigerant temperatures profiles of the condenser confirmed thermal energy dissipation.

Air-to-water heat pump assessment: Part 2 – Exergetic and exergoeconomic analyses

This study is part 2 of the investigation on the exergetic and exergoeconomic parameters of an existing system with an air-to-water heat pump unit as a heat source. Part 1 presents the used experimental setup. The main aim of the conducted experimental tests is to develop models of produced heat rate and energetic COP at different ambient conditions. The obtained data is used in Part 2 of the study where the exergetinc and exergoeconomic assessment is carried out. The exergetic and exergoeconomic analysis was performed at dynamically changing ambient parameters. The considered operation modes of the air-to-water heat pump (AWHP) unit and backup heater (BUH) were evaluated based on Seasonal Exergetic Efficiency. For the exergoeconomic analysis, the SPECO method is used. Thus, this paper provides an exhaustive understanding of the exergy and exergoeconomic performance of the considered air-to-water heat pump system.

Economic Analysis of Heat Pump Recovery System for Circulating Water Waste Heat in Power Plant

The use of heat pump technology to recover the waste heat of circulating water from the power plant instead of steam extraction for heating can not only improve the thermal efficiency of the unit and reduce the loss of cold source, but also has great advantages in energy saving. This paper uses absorption and compression heat pumps to recover the waste heat of circulating water in the power plant to study its energy-saving benefits. Under the same heating load, the economics of the two heat pumps are calculated and analyzed. The results show that the energy-saving benefits of absorption heat pump units are far greater than compression units. But in terms of water saving, the water saving capacity of the compression heat pump unit is higher than that of the absorption heat pump.