1991 Fiscal Year Final Research Report Summary
Phase Change Characteristics of Alternative Refrigerants in Double-tube Heat Exchanger
Grant-in-Aid for General Scientific Research (B)
|Allocation Type||Single-year Grants|
|Research Institution||Kyushu University|
FUJII Tetsu Kyushu Univ., Institute of Advanced Material Study, Professor, 機能物質科学研究所, 教授 (20038574)
SHINZATO Kan-ei Kyushu Univ., Institute of Advanced Material Study, Associate Professor, 機能物質科学研究所, 助教授 (30101463)
TAKAMATSU Hiroshi Kyushu Univ., Institute of Advanced Material Study, Associate Professor, 機能物質科学研究所, 助教授 (20179550)
KOYAMA Shigeru Kyushu Univ., Institute of Advanced Material Study, Associate Professor, 機能物質科学研究所, 助教授 (00153693)
|Project Period (FY)
1990 – 1991
|Keywords||Phase change / Double-tube evaporator / Double-tube condenser / Alternative refrigerants / Nonazeotropic refrigerant mixture / Smooth tube / Grooved tube / Transient response|
In this research project condensation and evaporation of alternative refrigerants and nonazeotropic refrigerant mixtures have been investigated experimentally to obtain the basic data which are necessary to develop heat pump/refrigeration systems using environmentally acceptable refrigerants as working fluids. Pure refrigerants of HCFC22, CFC114, CFC12 and HFC134a and nonazeotropic refrigerant mixtures (NARMs) of HCFC22 and CFC114 were used as working fluids. The double-tube heat exchangers were used as test condenser and evaporator. The results are as follows :
(1) The condensation heat transfer coefficient of pure refrigerants is correlated well with the equation obtained by modifying a semi-empirical equation of Nozu et al.
(2) For condensation of NARMs, a correlation equation of vapor mass transfer is obtained under some assumptions, and a new method to predict the heat transfer characteristics in a double-tube condenser is proposed.
(3) The evaporation heat transfer coefficient of pure refrigerants in the annular flow regime is correlated well with the equation obtained by developing Chen's idea.
(4) A correlation equation for evaporation heat transfer coefficient of NARMs is also obtained by modifying the equation of pure refrigerants.
(5) Transient characteristics of evaporation heat transfer and pressure drop of HCFC 22 in a double-tube heat exchanger are obtained and it is found that the transient heat transfer coefficient is lower than that for steady flow.
Research Products (10results)