Thermodynamic Analysis With Energy Recovery Comparison of Transcritical CO2 Heat Pump System Using Various Expansion Devices

Al-Tameemi, M. R. J., Abed, K. N., Khalif Salem, T. and Yu, Z. (2021) Thermodynamic Analysis With Energy Recovery Comparison of Transcritical CO2 Heat Pump System Using Various Expansion Devices. In: 2nd International Scientific Conference of Engineering Sciences (ISCES 2020), Diyala, Iraq, 16-17 Dec 2020, 012082. (doi:10.1088/1757-899X/1076/1/012082)

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Abstract

The high irreversibility caused by the expansion valve in the conventional transcritical CO2 heat pump cycle has been reported as the major drawback on the overall system performance. To overcome this problem and recover some of the energy lost, different isentropic expansion devices such as turbine expander and two phase ejector have been proposed. This study aims to numerically compare the performance of the transcrtical CO2 heat pump in terms of first and second law of thermodynamics. In addition, the energy recovered by the two phase ejector and the turbine expander cycles have been evaluated. The pressure recovery and entrainment ratio in the ejector device were investigated comprehensively. Two numerical models using MATLAB and ASPEN PLUS software have been developed, and REFPROP database was used to estimate the refrigerant thermophysical properties. The results showed that the heating coefficient of performance (COPh) of the ejector cycle is higher than that of the turbine and valve cycles by 10.15 % and 20.84 % respectively. In addition, the ejector cycle has the highest second law efficiency (0.1) and the recovered energy is (0.63 kW) compared to (0.107 kW) gained by the turbine cycle. The ejector device has the least exergy destruction (0.2 kW) and can recover 0.7 Mpa of the pressure losses.

Item Type:Conference Proceedings
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Al-Tameemi, Mohammed and Yu, Professor Zhibin
Authors: Al-Tameemi, M. R. J., Abed, K. N., Khalif Salem, T., and Yu, Z.
College/School:College of Science and Engineering > School of Engineering > Systems Power and Energy
ISSN:1757-8981
Published Online:25 February 2021
Copyright Holders:Copyright © 2021 IOP Publishing Ltd
First Published:First published in IOP Conference Series: Materials Science and Engineering 1076: 012082
Publisher Policy:Reproduced under a Creative Commons License

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