Transient behavior of three-fluid heat exchanger with three thermal communications under step change in inlet temperature of fluids using finite element method

摘要

In the present paper the transient temperature response of a counter-flow three-fluid heat exchanger with three thermal communications is investigated numerically using finite element method. Comparison with the previously published steady state results shows excellent agreement. The effects of step change in inlet temperature of fluids on time to reach steady state, outlet temperature of fluids, effectiveness are studied. Variation of design parameters like H-1, H-2 R-1, R-2 and NTU is also studied. The time to reach the steady state is independent of the amplitude of step change in the inlet temperature of fluids. For a step-change in the inlet temperature of the any fluid, the outlet temperature of other two fluids reach steady state faster than the fluid whose inlet temperature is changed. This method is so versatile that it could be applied to calculate the exponential, sinusoidal, ramp disturbances in inlet temperatures of any of the fluids. (C) 2016 Elsevier Ltd. All rights reserved.