Accession Number : ADA291150

Title :   Fundamental Studies in Cryogenic Cooling of Power Electronics.

Descriptive Note : Interim rept. 1 Sep 93-1 Aug 94,

Corporate Author : KENTUCKY UNIV LEXINGTON DEPT OF MECHANICAL ENGINEERING

Personal Author(s) : Chow, L. C. ; Sehmbey, M. S. ; Hahm, O. J. ; Chui, C. J.

PDF Url : ADA291150

Report Date : SEP 1994

Pagination or Media Count : 65

Abstract : This study details the results from experiments conducted to study the heat transfer characteristics during liquid nitrogen spray cooling and pool boiling from a heater array. Four different nozzles at various pressures were used to study the variation in spray cooling heat transfer at liquid nitrogen temperature. Effect of nozzle and flow rate on the critical heat flux and the heat transfer coefficient are presented. This study also provides empirical correlations for the spray cooling characteristics. The critical heat flux and the heat transfer coefficient have been correlated using non-dimensional numbers. The study also shows the importance of surface roughness for spray cooling with liquid nitrogen. The rougher surfaces were shown to have significantly higher heat transfer rates and similar critical heat fluxes occurring at lower temperatures. The results from experiments conducted to study the pool boiling heat transfer from a vertical array with flush mounted heat sources are also presented. The lower heaters were found to enhance the heat transfer from the upper heaters due to bubble pumped convection.

Descriptors :   *POWER EQUIPMENT, *LIQUID COOLING, HEAT TRANSFER, LOW TEMPERATURE, HIGH RATE, SURFACE ROUGHNESS, ELECTRONIC EQUIPMENT, ARRAYS, CORRELATION, NOZZLES, MOUNTS, LIQUID NITROGEN, CONVECTION(HEAT TRANSFER), HEAT FLUX, CRYOGENICS, SPRAYS, PUMPING, HEAT TRANSFER COEFFICIENTS, BOILING.

Subject Categories : Air Condition, Heating, Lighting & Ventilating
      Electricity and Magnetism

Distribution Statement : APPROVED FOR PUBLIC RELEASE