CHARACTERIZATION OF THE RESPONSE OF A THERMAL EXCHANGER WHEN SUBMITTED TO SIMULTANEOUS STEPS IN TEMPERATURE

In this paper we try to characterize the transient behaviour of parallel or counterflow heat exchangers when the two inlets are submitted at the same time to steps of temperature. The analysis lies on a two-parameter model for the temperature response, including a time lag t(r) and a time constant tau. By the mean of a time-dependent energy balance, we obtain an analytical expression of tau. Many special cases deduced from the general formulation are considered. This study is completed by a parametric analysis. Experimental investigations realized in various situations show a good agreement with theoretical results.