A Self-Regulating Freezable Heat Exchanger for Spacecraft

Award Information
Agency: National Aeronautics and Space Administration
Branch: N/A
Contract: NNX13CJ46C
Agency Tracking Number: 110137
Amount: $687,217.00
Phase: Phase II
Program: STTR
Awards Year: 2013
Solicitation Year: 2011
Solicitation Topic Code: T6.01
Solicitation Number: N/A
Small Business Information
12345 West 52nd Avenue, Wheat Ridge, CO, 80033-1916
DUNS: 181947730
HUBZone Owned: N
Woman Owned: N
Socially and Economically Disadvantaged: N
Principal Investigator
 Robert Copeland
 Principal Investigator
 (303) 940-2323
Business Contact
 John Wright
Title: Chief Technology Officer
Phone: (303) 940-2300
Email: krhodus@tda.com
Research Institution
 University of Colorado at Boulder
 NOT Available
 572 UCB
Office of Contracts & Grants
Boulder, CO, 80309
 () -
 Domestic nonprofit research organization
A spacecraft thermal control system must keep the vehicle, avionics and atmosphere (if crewed) within a defined temperature range. Since water is non-toxic and good for heat transport, it is typically used as the coolant that circulates within the crew cabin boundary. This loop then interfaces with another low freeze point fluid, such as ammonia, for transport of heat to a radiator where the temperatures can be considerably below the freezing point of water. The volumetric expansion during freeze usually prevents its use in external systems since freezing will damage the components. Yet, if the system can accommodate the forces generated by freezing, then selectively allowing parts of a heat exchanger to freeze can be used to passively increase the turn-down of the heat rejection from radiators. TDA Research, Inc. has been developing freezable water/ice phase change heat exchangers for several years that offer several advantages: they can eliminate the need for a separate heavy Freon or ammonia loop; use the buildup of ice to regulate the rate of heat transfer, and the endotherm of melting ice can absorb peak loads from the spacecraft to reduce the size and mass of the radiator. Therefore, TDA Research and the University of Colorado set out to demonstrate a lightweight and freeze tolerant water/ice heat exchanger to passively regulate the heat rejection rate from the water coolant loop of a manned spacecraft to its heat sink systems. The heat exchanger has no actively moving parts and is thus extremely reliable. In Phase I, we designed and built a self-regulating freezable heat exchanger that we put through 191 freeze/thaw cycles without damage and it has the capability to transfer the loads expected in crewed spacecraft. In Phase II, we will design, build and test a large-scale freeze tolerant water/ice heat exchanger that forms the heart of a thermal control system that we will deliver to NASA.

* Information listed above is at the time of submission. *

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