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An evaporative heat sink has been designed and built by AlliedSignal for NASA's Johnson Space Center. The unit is a demonstrator of a primary heat exchanger for NASA's prototype Crew Return Vehicle (CRV), designated the X-38. The primary heat exchanger is responsible for rejecting the heat produced by both the flight crew and the avionics. Spacecraft evaporative heat sinks utilize space vacuum as a resource to control the vapor pressure of a liquid. For the X-38, water has been chosen as the heat transport fluid. A portion of this coolant flow is bled off for use as the evaporant. At sufficiently low pressures, the water can be made to boil at temperatures approaching its freezing point. Heat transferred to liquid water in this state will cause the liquid to evaporate, thus creating a heat sink for the spacecraft's coolant loop. The CRV mission requires the heat exchanger to be compact and low in mass.

A family of ten coldplates has been developed. These form an integral part of the International Space Station Alpha internal thermal control system (ITCS) and provide necessary cooling for electronics and experimental equipment. These coldplates are robust single-passage, single-pass, plate-fin heat exchangers. They provide surface-mounted equipment cooling with a minimum coolant pressure drop, minimum weight, and maximum service life at an economical cost. The ten coldplates vary in size, thermal performance, and equipment mounting configuration. This paper describes the design and performance of each coldplate. Data from performance tests and performance derivations based on the test data are presented. These data are presented in a form suitable for use in the design of equipment applications.

A flexible fire detection system is required in order to monitor Space Station Freedom pressurized volumes, including spaces which may be inaccessible to the crew, or may be unattended for long periods of time. The system uses flame detectors to survey open areas for radiation at wavelengths and intensities characteristic of combustion, and uses smoke detectors to monitor particulates in open areas and in air circulation ducts. This paper briefly reviews the design of the system and the detectors and presents results of development testing of the smoke detectors. The duct-type smoke detector has met all Space Station Freedom performance requirements.