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Fluid Line Evacuation and Freezing Experiments for Digital Radiator ConceptThe digital radiator technology is one of three variable heat rejection technologies being investigated for future human-rated NASA missions. The digital radiator concept is based on a mechanically pumped fluid loop with parallel tubes carrying coolant to reject heat from the radiator surface. A series of valves actuate to start and stop fluid flow to di erent combinations of tubes, in order to vary the heat rejection capability of the radiator by a factor of 10 or more. When the flow in a particular leg is stopped, the fluid temperature drops and the fluid can freeze, causing damage or preventing flow from restarting. For this reason, the liquid in a stopped leg must be partially or fully evacuated upon shutdown. One of the challenges facing fluid evacuation from closed tubes arises from the vapor generated during pumping to low pressure, which can cause pump cavitation and incomplete evacuation. Here we present a series of laboratory experiments demonstrating fluid evacuation techniques to overcome these challenges by applying heat and pumping to partial vacuum. Also presented are results from qualitative testing of the freezing characteristics of several different candidate fluids, which demonstrate significant di erences in freezing properties, and give insight to the evacuation process.
Document ID
20150006927
Document Type
Conference Paper
External Source(s)
Authors
Berisford, Daniel F. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Birur, Gajanana C. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Miller, Jennifer R. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Sunada, Eric T. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Ganapathi, Gani B. (Jet Propulsion Lab., California Inst. of Tech. Pasadena, CA, United States)
Stephan, Ryan (NASA Johnson Space Center Houston, TX, United States)
Johnson, Mark (Boise State Univ. Boise, ID, United States)
Date Acquired
April 29, 2015
Publication Date
July 18, 2011
Subject Category
Fluid Mechanics and Thermodynamics
Meeting Information
International Conference on Environmental Systems (ICES)(Portland, OR)
Distribution Limits
Public
Copyright
Other
Keywords
human space flight
digital variable radiator