Energy analysis of heat exchanger in a heat exchanger network

Abstract

For many years now, heat exchanger optimization has been a field of research for a lot of scientists. Aims of optimization are different, having in mind heat ex-changer networks with different temperatures of certain streams. In this paper mathematical model in dimensionless form is developed, describing operation of one heat exchanger in a heat exchanger network, with given overall area, based on the maximum heat-flow rate criterion. Under the presumption of heat ex-changer being a part of the heat exchanger network, solution for the given task is resting in a possibility of connecting an additional fluid stream with certain tem-perature on a certain point of observed heat exchanger area. The connection point of additional fluid stream determines the exchanging areas of both heat ex-changers and it needs to allow the maximum exchanged heat-flow rate. This needed heat-flow rate achieves higher value than the heat-flow rate acquired by either of streams. In other words, a criterion for the existence of the maximum heat-flow rate, as a local extremum, is obtained within this mathematical model. Results of the research are presented by the adequate diagrams and are inter-preted, with emphasis on the cases which fulfill and those which do not fulfill the given condition for achieving the maximum heat-flow rate.