EXPERIMENTAL PERFORMANCE EVALUATION OF A DISK AND DOUGHNUT TYPE HEAT EXCHANGER.

An experimental study was conducted in which 158-mm-dia disk and doughnut type 1-2 oil coolers were tested for various combinations of flow rates and clearances between the doughnut baffle and the shell. Oil coolers of 45 L per minute capacity were tested at the diametral clearances of 0. 6 mm, 0. 87 mm, and 1. 25 mm between the doughnut baffle and shell for various flow rates of oil and water. The decrease in overall heat transfer coefficient with increasing clearance is not significant for most practical purposes. In another series of tests, oil coolers of 90 L per minute capacity with shell surface roughnesses of 4 and 19 microns and diametral clearances of 0. 07 mm, 0. 33 mm, and 0. 59 mm were tested. Results indicate that the overall heat transfer coefficient increases with increasing clearance and surface roughness.