Isothermal continuous flow calorimeter measures the thermal characteristics of space batteries undergoing typical orbital cycling. This is 28 times as sensitive as calorimeters previously used

Foley, R. T.

Webster, W. H.

English

NASA Technical Reports Server

December 1967	 Brief 67-10615 
NASA TECH BRIEF 
NASA Tech Briefs are issued to summarize specific innovations derived from the U.S. space program, 
to encourage their commercial application. Copies are available to the public at 15 cents each 
from the Clearinghouse for Federal Scientific and Technical Information, Springfield, Virginia 22151. 
Improved Calorimeter Provides Accurate Thermal Measurements of 
Space Batteries 
Compression Fitting 	 Return To Thermal 
Ballast Tank 
From Internal 
Heat Exchanger 
Hot Junction 
Cold Junction
Tubing 
Rubber Stopper	 PVC Plumbing Tee 
PVC Support
CALORIMETER AND AIR JACKET	 (1/4 Scale) 
The problem: 
To design and construct a highly accurate calorim-
eter for measuring the thermal characteristics of space 
batteries undergoing typical orbital cycling. Over 200 
existing designs were analyzed, but none were particu-
larly suited for the desired measurement. 
The solution: 
An isothermal continuous flow calorimeter was de-
veloped and calibrated from 0.10 to 1.00 watt, the
thermal output range characteristic of nickel-cad-
mium space batteries. The thermal response was found 
to be linear in this range and the instrument was 
sensitive to 0.01 watt. This is 28 times as sensitive 
as calorimeters previously used. Temperature changes 
of 0.00096°C are detectable. 
How it's done: 
The improved continuous flow calorimeter was con-
structed of available components but incorporated the 
(continued overleaf) 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privately owned rights.
https://ntrs.nasa.gov/search.jsp?R=19670000614 2020-03-11T21:26:44+00:00Z
following modifications: 
(a) The direction of liquid flow through the cal-
orimeter is reversed. The oil enters at the bot-
tom of the calorimeter where it is sensed by 
the cold junction of the thermopile. It then 
passes over the heat generating source and 
exits at the top of the calorimeter where the 
hot junction thermopile is positioned. 
(b) The number of copper-constantan couples in 
the thermopile is increased from 20 to 25, in-
creasing its sensitivity and allowing for detec-
tion of a 0.00096°C temperature difference. 
(c) The junctions of the thermopile are positioned 
in the center of the now stream in a 0.75 inch 
diameter adjustable acrylic pipe. 
(d) The internal diameter of the exit pipe at the 
top of the calorimeter is reduced from 2 inches 
to 1.5 inches, making it the same size as the 
entrance pipe at the bottom of the calorimeter. 
(e) A special Lucite fixture holds the battery and 
calibration heater in exact position in the cal-
orimeter. 
(f) Cast iron pipes were replaced by polyvinyl 
chloride pipes to eliminate any byproducts of 
corrosion. 
(g) The sensitivity of measurement was increased 
by using a lightweight hydrocarbon oil with a 
heat capacity lower than water.
The calorimeter is large enough that the heat gen-
erating device and calibration heater do not impede 
liquid flow or contact the walls, yet it is small enough 
to maintain essentially isothermal conditions. The 
calorimeter is fabricated from 316 stainless steel in 
the form of a right circular cylinder with a volume of 
107.3 cubic inches. 
Note: 
Additional details are contained in Research into 
Fundamental Phenomena Associated with Spacecraft 
Electrochemical Devices— Calorimetry of Nickel-
Cadmium Cells, by W. H. Webster and R. T. Foley, 
The American University, Washington, D.C. 20016. 
Copies of this report are available from: 
Technology Utilization Officer 
Goddard Space Flight Center 
Greenbelt, Maryland 20771 
Reference: B67-10615 
Patent status: 
No patent action is contemplated by NASA. 
Source: W. H. Webster and R. T. Foley 
of The American University 
under contract to 
Goddard Space Flight Center 
(GSC-10003A) 
Brief 67-10615	 Category 01


Improved calorimeter provides accurate thermal measurements of space batteries

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