Open AccessThermodynamic analysis with energy recovery comparison of transcritical CO2 heat pump system using various expansion devices.
Author(s) -
Mohammed Ridha Jawad Al-Tameemi,
Khuder N. Abed,
Thamer Khalif Salem,
Zhibin Yu
Publication year - 2021
Publication title -
iop conference series. materials science and engineering
Language(s) - English
Resource type - Journals
eISSN - 1757-899X
pISSN - 1757-8981
DOI - 10.1088/1757-899x/1076/1/012082
Subject(s) - injector , transcritical cycle , refrigerant , isentropic process , thermodynamics , thermal expansion valve , heat pump and refrigeration cycle , turbine , coefficient of performance , exergy , exergy efficiency , heat pump , materials science , refrigeration , nuclear engineering , thermodynamic cycle , mechanical engineering , mechanics , gas compressor , heat exchanger , engineering , physics
The high irreversibility caused by the expansion valve in the conventional transcritical CO 2 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 CO 2 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 (COP h ) 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.