BA-92-05-5 -- EHD Boiling Enhancement in Shell-and-Tube Evaporators and its Application in Refrigeration Plants PDF

Investigates the electrohydrodynamic (EHD) enhancement of boiling heat transfer of refrigerants in the shell side of single- and nine-tube shell-and-tube heat exchangers. R114 was the working fluid in both cases. Three different tubes were examined in the single-tube heat exchanger, namely, smooth, low-fin, and an enhanced surface tube. The nine-tube test facility included two identical heat exchangers that had low-fin and smooth tube bundles. The EHD mechanism is introduced. The resulting effect of EHD on the boiling of dielectric fluids is then outlined. EHD-enhanced boiling heat transfer rates for single tubes are then presented. Experimental results obtained from the nine-tube evaporator incorporating both the smooth and low-fin tube bundles are also presented. Data from the nine-tube evaporator have been used in a theoretical model predicting the performance of a refrigeration plant with and without EHD at the evaporator. The improvements in the plant's coefficient of performance and refrigeration capacity were significant.

KEYWORDS: shell and tube evaporators, refrigeration, boiling, heat flow, refrigerants, tubes, shell and tube heat exchangers, evaporators, heat exchangers, R114, experiment, calculating, performance, coefficient of performance