Experimentally validated models of refrigerant distribution in microchannel heat exchangers used to evaluate charge reduction of various working fluids

microchannel;refrigerant charge;modeling heat exchangers

Padilla, Yadira ; Hrnjak ; Predrag S.

关键词: microchannel;    refrigerant charge;    modeling heat exchangers;   

Others  :  https://www.ideals.illinois.edu/bitstream/handle/2142/34318/Padilla_Fuentes_Yadira.pdf?sequence=1&isAllowed=y

美国|英语

来源: The Illinois Digital Environment for Access to Learning and Scholarship

【 摘 要 】

This thesis presents experimentally validated simulation models developed to obtain accurate prediction of microchannel heat exchanger performance and charge. Effects of using various correlations are presented and discussed with focus on microchannel condensers and evaporators. Experiments with different refrigerants including R290, R717, R1234yf, and R134a are used to validate the models. The experimentally validated models are used to compare the charge of various refrigerants.The procedure for charge reduction analysis described in the thesis is the reduction of the internal (refrigerant) volume of the condenser or evaporator until a pressure drop is obtained that results in a specified percent decrease in COP from the same refrigeration cycle with no pressure drop. Furthermore, the effect of mass flux on charge is studied and discussed. Lastly, prediction of charge in headers is explored and correlations for predicting charge in headers of microchannel condensers are presented.