S. Abdallah et S. Rooke, TRANSIENT-RESPONSE OF A SERPENTINE FINNED-TUBE CROSS-FLOW HEAT-EXCHANGER TO A STEP CHANGE IN INLET TEMPERATURE, Heat transfer engineering, 18(3), 1997, pp. 51-60
An analysis of the thermal response of a finned-tube, liquid-to-gas cr
oss-flow heat exchanger due to a step change in the liquid inlet tempe
rature is performed Closed-form solutions for the liquid and gas tempe
ratures as functions of space and time are obtained via the Laplace tr
ansform technique for both small and large arguments of the modified B
essel function of the first kind. Using four physically important dime
nsionless parameters, the response of the liquid and average gas outle
t temperatures are studied and presented in the time domain. The analy
sis is extended to a single-row serpentine coil geometry by accounting
for U-tube bends. Using a typical heat exchanger geometry, the effect
s of the tube bends are shown to be significant. Relevant applications
include automotive and HVAC heat exchangers and systems.