scholarly journals Enhancing Heating Performance of Low-Temperature Air Source Heat Pumps Using Compressor Casing Thermal Storage

Energies ◽  
2020 ◽  
Vol 13 (12) ◽  
pp. 3269 ◽  
Author(s):  
Zhongbao Liu ◽  
Fengfei Lou ◽  
Xin Qi ◽  
Yiyao Shen
Keyword(s):  
Low Temperature ◽  
Heat Pump ◽  
Waste Heat ◽  
Thermal Storage ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Pump System ◽  
Heat Pump System ◽  
Discharge Temperature ◽  
Vapor Injection

Air source heat pumps (ASHPs) are widely recognized as energy-saving and environmentally friendly heating and air-conditioning equipment with broad applications. However, when conventional ASHPs are operated at a low ambient temperature, they suffer from problems such as high discharge temperature and low heating efficiency. To address these problems, this study designed a new type of dual evaporator combined with a compressor casing thermal storage heat pump system (DE-CCTS) on the basis of a low-temperature air source heat pump water heater with enhanced vapor injection (EVI). The proposed DE-CCTS used thermal storage phase change material (PCM), which was filled in the secondary evaporator (the thermal storage heat exchanger), to recover the waste heat of the compressor casing. Unlike that in the original system under different ambient temperatures, the suction temperature increased by 0.1–1 °C, the discharge temperature decreased by 0.1–0.5 °C, and the coefficient of performance (COP) of DE-CCTS increased by 0.85–4.72% under the proposed system. These effects were especially evident at low temperatures.

TECHNOLOGY REVIEW OF TWO-STAGE VAPOR COMPRESSION HEAT PUMP SYSTEM

2013 ◽  
Vol 21 (03) ◽  
pp. 1330002 ◽  
Author(s):  
KOJO ATTA AIKINS ◽  
SANG-HYEOK LEE ◽  
JONG MIN CHOI
Keyword(s):  
Heat Pump ◽  
High Efficiency ◽  
Industrial Applications ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Two Stage ◽  
Pump System ◽  
Heat Pump System ◽  
Discharge Temperature ◽  
Increasing Demand

There is increasing demand for domestic and industrial refrigeration, space heating and air conditioning. Heat pump systems offer economical alternatives for recovering heat from different sources for use in these applications. As a renewable energy technology for sustainable environment, the heat pump's high efficiency and low environmental impact have already drawn a fair amount of attention all over the world. Some of these domestic and industrial applications require very low evaporating temperatures and very high condensing temperatures which induce high compressor pressure ratios beyond the practical range for single-stage heat pump cycles. These high pressure ratios also produce low coefficient of performance (COP) values and expose the compressor to high discharge temperature, low volumetric efficiency and damage. However, this challenge can be overcome by adopting two-stage heat pump cycles. In this paper, recent works on two-stage heat pump systems for various applications are reviewed. They include two-stage cycle with intercooling, two-stage cycle with refrigerant injection and two-stage cascade cycle. Research and innovative designs of systems that make use of these two-stage cycles have been able to get heat pumps to handle applications with lower and higher temperatures, while enhancing heating capacity up to 30% and COP up to 31%.

Photovoltaic thermal collector assisted heat pumps using environment-friendly working fluids

2020 ◽  
pp. 095440892094736
Author(s):  
AA Ammar ◽  
K Sopian ◽  
M Mohanraj
Keyword(s):  
Heat Pump ◽  
Energy Performance ◽  
Heat Pumps ◽  
Payback Period ◽  
Photovoltaic System ◽  
Coefficient Of Performance ◽  
Photovoltaic Module ◽  
Pump System ◽  
Heat Pump System ◽  
Thermal Evaporator

In this research, a photovoltaic-thermal collector assisted heat pump has been developed and tested its performance under the tropical climatic conditions of Malaysia. The refrigerants such as, R134a and R1234yf were selected based on its thermodynamic and thermo-physical properties. The temperature of the photovoltaic module was theoretically predicted under the influence of tube diameter, tube spacing and refrigerant mass flow rate. Further, the energy performance of the photovoltaic-thermal evaporator and the heat pump system are investigated experimentally. Finally, the economical feasibility of the photovoltaic-thermal collector evaporator was assessed for the period of 20 years. The results showed that, the tube spacing and diameter of the copper tubes used in the photovoltaic-thermal evaporator/collector using R134a and R1234yf were optimized to 80 mm and 12.7 mm, respectively. It was observed that, during the clear sunny day, the average photovoltaic module temperature was reduced to 30.9 °C under the influence of panel cooling using refrigerant. The output of the panel was enhanced by 21%–44% with increase in solar radiation from 400 W/m2 to 1000 W/m2. The coefficient of performance of the heat pump was varied from 4.8 to 6.84 with an average coefficient of performance of 5.8 during clear sunny days. The life cycle economic analysis indicated that, the photovoltaic-thermal collector evaporator assisted heat pump has a payback period of 3 years, whereas the reference photovoltaic system has a payback period of 8 years.

scholarly journals Performance and Optimization Study of R290 as Alternative Refrigerant for R22 in Low Temperature Heat Pump System

2021 ◽  
Vol 2108 (1) ◽  
pp. 012089
Author(s):  
Yun Zhang ◽  
Cichong Liu ◽  
Wanyong Li ◽  
Junye Shi ◽  
Jiangping Chen
Keyword(s):  
Low Temperature ◽  
Heat Pump ◽  
Pump System ◽  
Heat Pump System ◽  
Exhaust Temperature ◽  
Discharge Temperature ◽  
Temperature Environment ◽  
Temperature Heat ◽  
Overall Performance ◽  
Temperature And Pressure

Abstract This paper mainly studies the replacement performance of R290 in R22 low temperature heat pump system from the experimental point of view. By comparing the performance differences under different working conditions, it is found that when R22 is directly extracted from the original system and filled with R290, the heat capacity and COP of the system are attenuated, and the compressor discharge temperature and pressure of the R290 system are higher than those of the original R22 system in low temperature environment. Through the analysis of the system components, it can be considered that the main reason for the above phenomenon is that the compressor displacement of the R22 system is too large and does not match the R290 system. Therefore, in order to meet the safety requirements of the system and improve the overall performance of R290 in the low temperature heat pump system at the same time, it is considered to replace the compressor with a smaller displacement which is more matched with R290 in the system. The experimental results show that the compressor displacement optimization of the R290 low temperature heat pump system can effectively reduce the exhaust temperature and pressure of the system and improve the overall performance of the system. The COP of the optimized R290 low temperature heat pump system is 6.5% higher than that of the original R22 system, and the exhaust temperature in the low temperature environment is reduced by 36% to below 80 C.

scholarly journals Implementation of a geothermal heat pump system in a solar passive house

2019 ◽  
Vol 85 ◽  
pp. 07014
Author(s):  
Gheorghe Ilisei ◽  
Tiberiu Catalina ◽  
Marian Alexandru ◽  
Robert Gavriliuc
Keyword(s):  
Heat Pump ◽  
Electricity Consumption ◽  
Heat Pumps ◽  
Coefficient Of Performance ◽  
Passive House ◽  
Geothermal Heat ◽  
Pump System ◽  
Heat Pump System ◽  
Major Index ◽  
Passive Houses

Underground energy sources are becoming increasingly popular and now geothermal heat pumps are frequently used to heat/cool different types of buildings, including for solar passive houses. This article aims at giving a contribution in the development of the thermal modelling of borehole heat storage systems, investigating the possibility of a GSHP (ground source heat pump) implementation with vertical boreholes in a solar passive house. A case study analysing a residential solar passive house is presented as a suitable modelling tool for the estimation of the thermal behaviour of GSHP systems by combining the outcome from different modelling programs. The software DesignBuilder, Earth Energy Designer and a sizing method for borehole’s length are used for producing the numerical results. The results highlight that the length of the borehole, a major index in estimating the system’s cost, is directly influenced by fundamental variables like thermal conductivity of grout or soil. Additionally, correlations between these parameters and the coefficient of performance of GSHP were made. Furthermore, the length of borehole is very important as it is responsible for almost half of the total installation cost and triggered a difference in electricity consumption of the GSHP up to 14%.

Study on Economized Vapor Injection Heat Pump System Using Refrigerant R32

2016 ◽  
Vol 24 (01) ◽  
pp. 1650006 ◽  
Author(s):  
Yaoguang Shi ◽  
Xianmin Guo ◽  
Xinyu Zhang
Keyword(s):  
Heat Pump ◽  
Injection Pressure ◽  
Pump System ◽  
Heat Pump System ◽  
Heating Efficiency ◽  
Discharge Temperature ◽  
Vapor Injection ◽  
Potential Alternative ◽  
Low Global Warming Potential ◽  
Injection Ratio

The refrigerant R32 is considered as a potential alternative refrigerant of R410A because of its low global warming potential (GWP) and the basic thermodynamic parameters. It can effectively improve the heating efficiency and reduce the discharge temperature of the compressor to use the economized vapor injection (EVI) refrigeration system. In this paper, the performance of the EVI heat pump system using refrigerant R32 is investigated experimentally under the conditions of the evaporating temperature ranged from [Formula: see text]C to [Formula: see text]C. The experimental results indicate that the injection ratio, heat capacity and power consumption of the EVI heat pump system increase with the injection pressure. The maximum injection ratio of the EVI heat pump system is about 33% under the evaporating temperature of [Formula: see text]C. For the EVI heat pump system, the system COP achieves the maximum value as the injection pressure ranges from 1.48[Formula: see text]MPa to 1.54[Formula: see text]MPa when the evaporating temperature is lower than [Formula: see text]C. The discharge temperature of the EVI heat pump system drops by 11[Formula: see text]C under the evaporating temperature of [Formula: see text]C. As the evaporating temperature is below [Formula: see text]C, the COP of the EVI heat pump system is higher than that of the traditional single stage heat pump.

Thermodynamic and Economic Analysis of Heat Pumps for Energy Recovery in Industrial Processes

1980 ◽  
Vol 102 (3) ◽  
pp. 173-180 ◽  
Author(s):  
A. H. Urdaneta-B ◽  
P. S. Schmidt
Keyword(s):  
Case Studies ◽  
Heat Pump ◽  
Heat Recovery ◽  
Waste Heat ◽  
Heat Pumps ◽  
Design Parameters ◽  
Pump System ◽  
Economic Return ◽  
Processing Application ◽  
Heat Pump System

A computer code has been developed for analyzing the thermodynamic performance, cost and economic return for heat pump applications in industrial heat recovery. Starting with basic defining characteristics of the waste heat stream and the desired heat sink, the algorithm first evaluates the potential for conventional heat recovery with heat exchangers, and if applicable, sizes the exchanger. A heat pump system is then designed to process the residual heating and cooling requirements of the streams. In configuring the heat pump, the program searches a number of parameters, including condenser temperature, evaporator temperature, and condenser and evaporator approaches. All system components are sized for each set of parameters, and economic return is estimated and compared with system economics for conventional processing of the heated and cooled streams (i.e., with process heaters and coolers). Several thermodynamic and economic performance ratios are computed for comparative evaluation of heat pumps versus conventional systems. Two case studies are evaluated, one in a food processing application and the other in an oil refinery unit. Results of the case studies are presented to illustrate the use of the program and to show the sensitivity of heat pump system economics to the various design parameters.

scholarly journals Seasonal storage of residential exhaust air and sewage waste heat

2021 ◽  
Vol 246 ◽  
pp. 06009
Author(s):  
Janne Hirvonen ◽  
Juha Jokisalo ◽  
Risto Kosonen
Keyword(s):  
Heat Pump ◽  
Waste Heat ◽  
Residential Buildings ◽  
Heat Pumps ◽  
Ground Source Heat Pump ◽  
Pump System ◽  
Ground Source Heat Pumps ◽  
Heat Pump System ◽  
Ground Source ◽  
Sewage Waste

Most Finnish residential buildings have been built before ventilation heat recovery options became mandatory. Exhaust air heat pumps are an effective way to reduce emissions, but they cannot cover all heating demand. Ground-source heat pumps can be designed to meet all loads, but they require corresponding amounts of space both above and below ground. This simulation study combines residential ventilation and sewage waste heat with a ground-source heat pump system to improve system sustainability and cost-effectiveness. A hybrid waste heat and ground-source heat pump system was shown to have 20% lower life cycle costs compared to a pure ground-source heat pump system. It also maintained sustainable ground temperature levels over the long term, while reducing above-ground space requirements by 95%.

The Comparison of Experiment Results and CFD Simulation in the Heat Pump System Using Thermobank and Two-Phase Ejector for Heating Room and Cold Storage

2016 ◽  
Vol 24 (01) ◽  
pp. 1650004 ◽  
Author(s):  
Le Ngoc Cuong ◽  
Jong-Taek Oh
Keyword(s):  
Heat Pump ◽  
Cold Storage ◽  
Cfd Simulation ◽  
Waste Heat ◽  
Coefficient Of Performance ◽  
Two Phase ◽  
Pump System ◽  
Heat Pump System ◽  
Dimension Formula ◽  
Floor Panel

In this paper, the heat pump system has been developed by CFD simulation and experimental investigation. It studies the thermal behavior of a thermobank and COP on heat pump system and cold storage. The thermobank stores the waste heat of during refrigeration cycles and this energy is used for defrosting process and heating room. It also reduces defrosting time and condensation load so that the temperature regulation in the cold storage is constant. The system is investigated experimentally and CFD simulated under thermobank. The dimension [Formula: see text] of cold storage is [Formula: see text][Formula: see text]m, thermobank is [Formula: see text][Formula: see text]mm. The temperature of ambient on CFD simulation process is 20[Formula: see text]C. This heat pump system can be used to keep preservation of agricultural products in cold storage warehouse together with floor panel heating for room in winter. The ejector is used in system with the aim of increasing coefficient of performance (COP) and decrease in compressor displacement. As the experimental results, its COP is increased about 38.57% when using thermobank and ejector in heat pump system.

scholarly journals Performance evaluation of heat pump system using R744/R161 mixture refrigerant

2014 ◽  
Vol 18 (5) ◽  
pp. 1673-1677
Author(s):  
Xian-Ping Zhang ◽  
Xin-Li Wei ◽  
Xiao-Wei Fan ◽  
Fu-Jun Ju ◽  
Lei Yang
Keyword(s):  
Heat Pump ◽  
Mass Fraction ◽  
Variable Mass ◽  
Heat Pumps ◽  
Montreal Protocol ◽  
Coefficient Of Performance ◽  
Pump System ◽  
Heat Pump System ◽  
Conservation Technology ◽  
Phase Out

As an efficient and energy conservation technology, heat pumps working with R22, which are scheduled to be phased out by Montreal Protocol, are widely used in China at present. The global deteriorating ecology environment would accelerate the phase-out time of R22 in developing countries. Therefore, as a matter of urgency, an eco-friendly substitute should be investigated in order to replace R22. Under this context, and with a consideration of the environmental protection, R744/R161 mixture refrigerant is proposed. R744/R161 mixture refrigerant?s condensation pressure is reduced and its flammability and explosivity are suppressed. A thermodynamic model is developed, and under the given working conditions, the performances of subcritical heat pump system using R744/R161 mixture of variable mass fraction are discussed and compared with those of the R22 system. The optimal mass fraction of R744/R161 is given, which corresponds to a maximal heating coefficient of performance. The simulation results show that R744/R161 mixture can work as a competitive alternative to R22 in heat pump system.

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