1994 NASA/ASEE Summer Faculty Fellowship Program Johnson Space Center

ABSTRACTThe increases in power demand and associated thermal managementrequirements of future space programs such as potential Lunar/Mars missionswill require enhancing the operating efficiencies of thermal management devices.Currently, the use of electrohydrodynamically (EHD) assisted thermal controldevices is under consideration as a potential method of increasing thermalmanagement system capacity. The objectives of the currently describedinvestigation included completing build-up of the EHD-Assisted Heat Pipe Testbed, developing test procedures for an experimental evaluation of the unassistedheat pipe, developing an analytical model capable of predicting the performancelimits of the unassisted heat pipe, and obtaining experimental data which woulddefine the performance characteristics of the unassisted heat pipe.The information obtained in the currently proposed study will be used in order toprovide extensive comparisons with the EHD-assisted performance observationsto be obtained during the continuing investigation of EHD-Assisted heat transferdevices. Through comparisons of the baseline test bed data and the EHDassisted test bed data, accurate insight into the performance enhancingcharacteristics of EHD augmentation may be obtained. This may lead tooptimization, development, and implementation of EHD technology for futurespace programs.INTRODUCTIONThe power demand and thermal management requirements of future spaceprograms will require improving the efficiencies of thermal management devices.Currently, electrohydrodyamically assisted heat pipes are being considered forimplementation in spacecraft thermal management systems. Margo and Seyed-Yagoobi (1993) observed increases of up to 71% in forced and free convectionheat transfer by utilizing EHD assistance in a convection loop. The intent of thecurrent investigation was to obtain baseline (i.e., without the operational EHDpump) performance data for a EHD-assisted heat pipe in order to accuratelyquantify the enhancing characteristics of the EHD pump.Electrohydrodynamic pumping occurs when an electric field interacts with freeelectric charges in a dielectric fluid. The electric field induces an electromotiveforce on the free electric charges, dragging the liquid and providing a pumpingeffect on the liquid medium. This phenomena is illustrated in fig. 1.10-2