NUMERICAL STUDY OF A LOW PERMEABILITY MICROPOROUS HEAT SINK FOR COOLING PHASED-ARRAY RADAR SYSTEMS

Microporous media is being used to develop an improved forced convecti on cold plate device for removing waste heat from high frequency phase d-array radar apertures. The waste heat, generated by transmit and rec eive microwave functions mounted in separate electronic modules, is co nducted to the surfaces of a thin rectangular enclosure (cold plate) t hrough which coolant flows. The performance of the phased-array radar is known to deteriorate very rapidly when the difference in operating temperatures of identical electronic components within each module inc reases. The cold plate device investigated here, designed to minimize this temperature difference, consists of a microporous layer placed (b razed) within the cold plate. A theoretical transport model is develop ed around an extended system of two-dimensional equations obtained by considering a thin enclosure and integrating the original three-dimens ional equations along the direction of smaller dimension. Thermo/hydra ulic characteristics are obtained through numerical simulations consid ering a low permeability aluminum alloy porous layer, and air, water a nd PAO as coolants. A theoretical estimate of the global pressure drop across the cold plate is also obtained and compared with the numerica l results. The microporous cold plate provides substantially more unif orm operating temperature for identical components in all module housi ngs than a cold plate without porous layer. Results also suggest an in creased global heat transfer coefficient reducing the operational (jun ction) temperature of the electronics for the same waste hear. Copyrig ht (C) 1996 Elsevier Science Ltd.