Engineering Study Of Vapor Cycle Cooling Equipment For Zero-gravity Environment
This report discusses the results of an analytical and experimental study of space vehicle vapor cycle cooling systems operating in a zero-gravity environment. The evaporator temperature varied from 40 degrees F to 55 degrees F, and the condenser temperature varied between 150 degrees F and 250 degrees F; the evaporator cooling load varied from 400 BTU/min to 4000 BTU/min. The ultimate heat dissipation is by radiation to space. The study considers some of the problems encountered in the operation of a vapor cycle in a zero-gravity environment and presents solutions to these problems. Emphasis has been placed on the vapor-liquid separation problems in evaporation and condensation.
The vortex evaporator is presented as a solution to the zero-gravity evaporation problem. Its volume is less than that of a conventional plate-fin evaporator operating under a one-g environment, but its weight is greater. The spiral condenser is presented as a solution to the zero-g condenser problem; its volume is several times larger than the smallest tube-fin unit (operating at one-g) for the same conditions. An analysis for and design of a rotating condenser is shown. Wick materials are well suited to zero-gravity evaporators. The experimental work conducted in this study must be extended before any reliable design and construction of a wick evaporator is possible. Film condensation under zero gravity in the laminar region is also analyzed. For vapor cycles operating at large differences in condenser and evaporator temperature, the substitution of an expansion engine for the throttle valve results in a significant improvement in the cycle performance.
(PDF, 12.59 MB, 256 pages)