Thermal insulating material increases the rate of heat transfer from the interior of a chamber to a liquid nitrogen-filled metal jacket. A thin film of the material is bonded to the surface of the metal wall facing the liquid nitrogen

Allen, L. D.

English

NASA Technical Reports Server

Nitrogen
61 August 1965	 Brief 65-IO240 
NASA TECH BRIEF 
NASA Tech Briefs are issued by the Technology Utilization Division to summarize specific 
technical innovations derived from the space program. Copies are available to the public from 
the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia, 22151. 
Insulation Accelerates Rate of Cooling with Cryogenic Fluid 
HEAT FLOW	 TEMPERATURE 
I1
Temperature 
The problem: To increase the rate of heat transfer 
from the interior of a chamber to a liquid nitrogen-
filled metal jacket (cryopanel). The increased rate of 
heat transfer will shorten the time required to lower 
the chamber temperature. 
The solution: A thin film of thermal insulating ma-
terial (e.g., polytetrafluoroethylene) is bonded to the 
surface of the metal wall facing the liquid nitrogen. 
How it's done: As shown in the schematic illustra-
tion, heat from the chamber flows in series through 
the metal wall, the insulating film, a nitrogen-vapor 
film and the liquid nitrogen layer. Each of these layers 
presents a different thermal resistance to the flow of 
heat from the chamber into the liquid nitrogen; there-
fore the interface at each layer will be at a different 
temperature. The effect of the insulating film is to 
lower the temperature at point A, so that the thickness 
of the vapor film is less than it would be in the absence 
of an insulating film. The vapor film therefore has a 
lower thermal resistance, thus permitting an increased 
rate of heat transfer through the system. The com-
bined thermal resistance of the added insulating film 
and the vapor film is much smaller than the thermal
resistance of the vapor that would exist in the absence 
of the insulating film. As the insulating film ap-
proaches cryogenic temperature, its thermal conduc-
tivity changes; the thickness of this film must be an 
optimum for maximum heat transfer. 
Notes: 
I. In tests with a copper panel, cool-down from +50°F 
to —320°F was more than twice as fast with a thin 
film of polytetrafluoroethylene bonded to the cop-
per surface facing the liquid-vapor nitrogen. 
2. Inquiries concerning this invention may be directed 
to:
Technology Utilization Officer 
Manned Spacecraft Center 
P.O. Box 1537 
Houston, Texas, 77001 
Reference: B65-10240 
Patent status: NASA encourages the immediate 
commercial use of this invention. Inquiries about ob-
taining rights for its commercial use may be made to 
NASA, Code AGP, Washington, D.C., 20546. 
Source: Lou David Allen 
(MSC-161) 
Am	 Category No. 02 
IRW
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States Govern-
ment, nor NASA, nor any person acting on behalf of NASA: A. Makes 
any warranty or representation, express or implied, with respect to the 
accuracy, completeness, or usefulness of the information contained in
this document, or that the use of any information, apparatus, method, 
or process disclosed in this document may not infringe privately-owned 
rights; or B. Assumes any liabilities with respect to the use of, or for 
damages resulting from the use of, any information, apparatus, method, 
or process disclosed in this document.
https://ntrs.nasa.gov/search.jsp?R=19650000238 2020-03-11T17:18:52+00:00Z


Insulation accelerates rate of cooling with cryogenic fluid

Abstract

Similar works

Full text

Available Versions

NASA Technical Reports Server