scholarly journals Comparative Analysis of Heat Pump System with IHX Using R1234yf and R134a

2021 ◽  
Vol 65 (4) ◽  
pp. 363-373
Author(s):  
Róbert Sánta
Keyword(s):  
Heat Pump ◽  
Internal Heat ◽  
Energy Performance ◽  
Operating Conditions ◽  
Pump System ◽  
Heat Pump System ◽  
Internal Heat Exchanger ◽  
Heating Capacity ◽  
Wide Range ◽  
Compressor Power

This research presents an energy performance analysis of the heat pump system with internal heat exchanger (IHX). The mathematical model of the heat pump outlined in this paper has been created by the author, it is steady-state with lumped parameters. The experimental validation of the model has been carried out using R1234yf and R134a as refrigerant. The aim of this work is to compare the energy performance in a wide range of operating conditions of a monitored heat pump system using both refrigerants. Finally, the heating capacity for R1234yf was lower from 0.63 % to 7.54 % compared with R134a, while the compressor power was similar from 0.12 % to 3.51 %. The COP values of R1234yf were lower than those obtained of R134a, ranging from 1.39 % to 4.22 %.

THERMODYNAMIC ANALYSIS AND EXPERIMENTAL RESEARCH OF TRANSCRITICAL CO2 CYCLE WITH INTERNAL HEAT EXCHANGER AND DUAL EXPANSION

2013 ◽  
Vol 21 (01) ◽  
pp. 1350005 ◽  
Author(s):  
Z. WANG ◽  
Y. GONG ◽  
X. H. WU ◽  
W. H. ZHANG ◽  
Y. L. LU
Keyword(s):  
Heat Exchanger ◽  
Experimental Evaluation ◽  
Pressure Fluctuations ◽  
Internal Heat ◽  
Energy Performance ◽  
Evaporation Temperature ◽  
Internal Heat Exchanger ◽  
Side Pressure ◽  
Wide Range ◽  
Compressor Power

This work presents the experimental evaluation of the energy performance of transcritical CO2 refrigeration and heat pump systems. The optimal gas cooler pressures and the optimal COP have been analyzed from a thermodynamic point of view. The systems used a new dual expansion valve and a balance CO2 liquid receiver adjustment device, which can control high and low side pressure effectively. Moreover, we demonstrate the influence of the internal heat exchanger (IHX) on the systems' performances, on the basis of the analysis of the relative COP index RCOPI, the compressor power index RPCI and other parameters which can confirm the truth of. The experimental evaluation covers five evaporating levels (-10 to 10°C) and in a wide range of gas cooler pressures (75 to 120 bar). It is concluded that with the IHX system, compressor power is relatively low when the high side pressure is over 100 bar, and the evaporation temperature is below 0°C. The COP of the system without the IHX is slightly higher than the system with the IHX; it is increasing about 3% to 5%, when the evaporation temperature is over 5°C. Relative to the single expansion process, the dual expansion cycle can decrease the influence of pressure fluctuations of CO2 supercritical fluid and liquid mixture on the systems.

scholarly journals Numerical Analysis and Preliminary Experiment of a Solar Assisted Heat Pump Drying System for Chinese Wolfberry

Energies ◽  
2020 ◽  
Vol 13 (17) ◽  
pp. 4306 ◽  
Author(s):  
Zhongting Hu ◽  
Sheng Zhang ◽  
Wenfeng Chu ◽  
Wei He ◽  
Cairui Yu ◽  
...  
Keyword(s):  
Energy Consumption ◽  
Heat Pump ◽  
Electric Energy ◽  
Energy Performance ◽  
Operating Conditions ◽  
Pump System ◽  
Heat Pump System ◽  
Electric Energy Consumption ◽  
Drying System ◽  
Heat Pump Drying

The present work investigated a solar assisted heat pump system for drying Chinese wolfberry. The kinetic characteristic was firstly analyzed through a series of lab experiments. It was concluded that the Page model was the most suitable for predicting the heat and mass transfer of the wolfberry. Based on the wolfberry kinetic model, solar collector model and chamber air model, the coupled drying system model was developed. The accuracy of the mathematic model was determined through comparing with the preliminary experimental results. The influence of operating conditions on the thermal and energy performance of the dryer for the different operating mode was discussed. The drying weight of no more than 75 kg may be preferable in the stand-alone solar drying mode, and less than 15 h was needed to be dried. The electric energy consumption in the solar assisted the heat pump drying mode was lower than that in the stand-alone heat pump mode, and it was recommended that about 50 kg of wolfberry to be dried in the solar assisted heat pump system. Compared to the autumn drying, the reduction in the electric energy consumption was around 9.1 kWh during the 11 h summer drying process. The obtained results demonstrated the feasibility of the combined system for drying wolfberry, and also can provide the basic theoretical and experimental data support for the following research.

scholarly journals Experimental Study on the Cycle Performance Characteristics of the CO2 Heat Pump System under the Cooling Condition

2017 ◽  
Author(s):  
Hee Jeong Kang ◽  
Zhen Huan Wang ◽  
Jun Son ◽  
Sun-Joon Byun ◽  
Young-Chul Kwon
Keyword(s):  
Heat Exchanger ◽  
Heat Pump ◽  
Internal Heat ◽  
Optimal Operation ◽  
Performance Characteristics ◽  
Cycle Performance ◽  
Pump System ◽  
Heat Pump System ◽  
Operation Conditions ◽  
Internal Heat Exchanger

Developing high performance HVAC system using natural refrigerants including carbon dioxide (CO2) has been important in respect of environmental preservation and associated technologies. Thus studies to optimize the HVAC (heating ventilation air conditioner) system using natural refrigerants through clarifying the cycle performance characteristics are necessary. The CO2 heat pump system using air and water sources was consisted to examine its performance characteristics, and by varying conditions of several factors that affect or characterize the system performance like the amount of refrigerant charge, EEV (electronic expansion valve) opening, and internal heat exchanger under cooling mode. The performance characteristics of CO2 heat pump system were tested by using an air enthalpy calorimeter. In the case of the CO2 heat pump system without internal heat exchanger, the opening of #3 EEV and #4 EEV was 60% and refrigerant charge amount was 5,600g. However, in the case of that with internal heat exchanger, the best performance was obtained when the opening of #2 EEV is 20%. From the present studies, it was observed that the performance variation and operational characteristics of the CO2 heat pump system were affected by design factors like refrigerant charge amount, EEV opening, and internal heat exchanger and thereby, the configuration on an optimal operation conditions of the system was enabled.

Thermodynamic Analysis and Experimental Investigation of Internal Heat Exchanger Influence on CO2 Trans-Critical Cycle Performance

2012 ◽  
Vol 614-615 ◽  
pp. 259-264
Author(s):  
Wen Hui Zhang ◽  
Zhe Wang ◽  
Yi Gong ◽  
Xue Hong Wu ◽  
Yan Li Lu
Keyword(s):  
Heat Exchanger ◽  
Experimental Evaluation ◽  
Internal Heat ◽  
Energy Performance ◽  
Point Of View ◽  
Cycle Performance ◽  
Evaporation Temperature ◽  
Internal Heat Exchanger ◽  
Wide Range ◽  
Compressor Power

This work present the experimental evaluation of the energy performance of trans-critical CO2refrigeration and heat pump systems. The optimal gas cooler pressure and the optimal COP have been analysed from a thermodynamic point of view. The experimental evaluation covers five evaporating levels (-10 to 10°C) and in a wide range of gas cooler outlet pressures (75 to 120bar). It is concluded that: With the the internal heat exchanger (IHX) system compressor power is relatively low, when the high side pressure is over 100bar, and the evaporation temperature is below 0°C. The COP of the system without IHX is slightly higher than the system with the IHX, it is increase about 3% to 5%, when the evaporation temperature is over 5°C.

scholarly journals Theoretical Analysis of a Single-Stage Gas-fired Ejector Heat Pump Water Heater

2021 ◽  
pp. 1-28
Author(s):  
Jeremy Spitzenberger ◽  
Pengtao Wang ◽  
Laith Ismael ◽  
Hongbin Ma ◽  
Ahmad Abuheiba ◽  
...  
Keyword(s):  
Heat Pump ◽  
Thermal Energy ◽  
Ambient Air ◽  
Single Stage ◽  
Coefficient Of Performance ◽  
Water Heater ◽  
Pump System ◽  
Heat Pump System ◽  
Heating Capacity ◽  
Condenser Temperature

Abstract Ejector driven systems have the ability to operate at high efficiencies, utilizing recycled thermal energy as a power source. For a typical ejector heat pump system, the increase of the condenser temperature reduces the coefficient of performance (COP). In addition, if the condenser temperature is higher than the critical temperature, the ejector may not function. In this situation, the condenser temperature must be reduced, and an additional heater will be utilized to heat the production water from the condenser temperature to the desired temperature. In this investigation, a single-stage gas-fired ejector heat pump (EHP) is investigated and thermodynamically modeled in order to optimize the system COP for the purpose of heating water by utilizing the thermal energy from the ambient air. The effects of the high-temperature evaporator (HTE) and low-temperature evaporator (LTE) temperatures on the ejector critical back pressure and the EHP system performance are examined for a HTE temperature range of 120-180 °C and LTE temperatures of 15.5, 17.5, and 19.5 °C. Results show that an optimized COP of the EHP system exists which depends on HTE and LTE temperatures, primary nozzle throat diameters. In addition, it is found that the EHP COP is independent of the ejector COP. From this investigation a maximum EHP COP of 1.31 is able to be achieved for a HTE temperature of 160 °C and a LTE temperature of 19.5 °C with a total heating capacity of 15.98 kW.

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