Problem of heat transfer in compact heat exchangers using variable thermal resistance

Abstract

The paper presents the results of a complex of studies, analysis of the efficiency of the heat exchangers of aircraft ACS, as well as developed methods for protecting the heat transfer surface from freezing and thermal stresses. The basis of the work was the results of experimental studies of heat and mass transfer of a three-phase flow of “moist air - supercooled water aerosol” with a negative temperature in the CPFHE channels. As well as previously developed methods for modeling the processes of local heat transfer in compact heat exchangers with two-phase coolants (condenser) and in the presence of thermal stresses at high temperatures of hot air (preliminary heat exchanger). The proposed methods are based on the idea of obtaining a given surface temperature by changing the thermal resistances during the heat transfer process. The improvement of the models consists in taking into account the variable thermal resistances along the length of the hot and cold tract. In particular, the parameters of heat transfer processes defined by the geometry of the fins and flow regimes, as well as local heat and mass transfer processes during phase transitions.