SIST-TP CEN/CLC/TR 17603-31-11:2021
(Main)Space engineering - Thermal design handbook - Part 11: Electrical Heating
Space engineering - Thermal design handbook - Part 11: Electrical Heating
In this Part 11, the use of electrical heaters and electrical coolers in spacecraft systems are described.
Electrical thermal control is an efficient and reliable method for attaining and maintaining temperatures. Solid state systems provide for flexibility in control of thermal regulation, they are resistant to shock and vibration and can operate in extreme physical conditions such as high and zero gravity levels. They are also easy to integrate into spacecraft subsystems.
The Thermal design handbook is published in 16 Parts
TR 17603-31-01 Part 1
Thermal design handbook – Part 1: View factors
TR 17603-31-01 Part 2
Thermal design handbook – Part 2: Holes, Grooves and Cavities
TR 17603-31-01 Part 3
Thermal design handbook – Part 3: Spacecraft Surface Temperature
TR 17603-31-01 Part 4
Thermal design handbook – Part 4: Conductive Heat Transfer
TR 17603-31-01 Part 5
Thermal design handbook – Part 5: Structural Materials: Metallic and Composite
TR 17603-31-01 Part 6
Thermal design handbook – Part 6: Thermal Control Surfaces
TR 17603-31-01 Part 7
Thermal design handbook – Part 7: Insulations
TR 17603-31-01 Part 8
Thermal design handbook – Part 8: Heat Pipes
TR 17603-31-01 Part 9
Thermal design handbook – Part 9: Radiators
TR 17603-31-01 Part 10
Thermal design handbook – Part 10: Phase – Change Capacitors
TR 17603-31-01 Part 11
Thermal design handbook – Part 11: Electrical Heating
TR 17603-31-01 Part 12
Thermal design handbook – Part 12: Louvers
TR 17603-31-01 Part 13
Thermal design handbook – Part 13: Fluid Loops
TR 17603-31-01 Part 14
Thermal design handbook – Part 14: Cryogenic Cooling
TR 17603-31-01 Part 15
Thermal design handbook – Part 15: Existing Satellites
TR 17603-31-01 Part 16
Thermal design handbook – Part 16: Thermal Protection System
Raumfahrttechnik - Handbuch für thermisches Design - Teil 11: Elektrisches Heizen
Ingénierie spatiale - Manuel de conception thermique - Partie 11: Chauffage électrique
Vesoljska tehnika - Priročnik o toplotni zasnovi - 11. del: Električno ogrevanje
General Information
Standards Content (Sample)
SLOVENSKI STANDARD
SIST-TP CEN/CLC/TR 17603-31-11:2021
01-oktober-2021
Vesoljska tehnika - Priročnik o toplotni zasnovi - 11. del: Električno ogrevanje
Space engineering - Thermal design handbook - Part 11: Electrical Heating
Raumfahrttechnik - Handbuch für thermisches Design - Teil 11: Elektrisches Heizen
Ingénierie spatiale - Manuel de conception thermique - Partie 11: Chauffage électrique
Ta slovenski standard je istoveten z: CEN/CLC/TR 17603-31-11:2021
ICS:
49.140 Vesoljski sistemi in operacije Space systems and
operations
SIST-TP CEN/CLC/TR 17603-31-11:2021 en,fr,de
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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TECHNICAL REPORT
CEN/CLC/TR 17603-31-
11
RAPPORT TECHNIQUE
TECHNISCHER BERICHT
August 2021
ICS 49.140
English version
Space engineering - Thermal design handbook - Part 11:
Electrical Heating
Ingénierie spatiale - Manuel de conception thermique - Raumfahrttechnik - Handbuch für thermisches Design -
Partie 11 : Chauffage électrique Teil 11: Elektrisches Heizen
This Technical Report was approved by CEN on 21 June 2021. It has been drawn up by the Technical Committee CEN/CLC/JTC 5.
CEN and CENELEC members are the national standards bodies and national electrotechnical committees of Austria, Belgium,
Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia,
Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
CEN-CENELEC Management Centre:
Rue de la Science 23, B-1040 Brussels
© 2021 CEN/CENELEC All rights of exploitation in any form and by any means Ref. No. CEN/CLC/TR 17603-31-11:2021 E
reserved worldwide for CEN national Members and for
CENELEC Members.
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Table of contents
European Foreword . 6
1 Scope . 7
2 References . 8
3 Terms, definitions and symbols . 9
3.1 Terms and definitions . 9
3.2 Symbols .9
4 Electrical heating . 11
4.1 General . 11
4.1.1 Conductive element . 11
4.1.2 Electrical terminations . 11
4.1.3 Electrical insulation . 12
4.1.4 Outgassing . 13
4.2 Space applications. 14
4.2.1 Viking spacecraft . 14
4.2.2 Fltsatcom spacecraft . 14
4.2.3 OTS . 14
4.2.4 SPOT . 15
4.2.5 Miscellaneous utilization . 15
4.3 Power requirement estimation . 15
4.3.1 Simplification assumptions . 16
4.3.2 Conduction losses . 16
4.3.3 Radiation losses . 16
4.3.4 Process heat requirements . 16
4.3.5 Operating heat requirements . 16
4.3.6 Warm-up heat requirements . 17
4.4 Regulation of electrical heaters . 17
4.4.1 Temperature sensor . 18
4.4.2 Temperature controller . 18
4.5 Existing systems . 19
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4.5.1 Minco Products Inc. . 19
4.5.2 Isopad Limited . 28
5 Electrical cooling . 35
5.1 General . 35
5.1.1 Description . 35
5.1.2 Advantages of use . 35
5.1.3 Physical phenomena . 35
5.1.4 Multi-stage thermoelectric devices . 36
5.1.5 Heat dissipation . 37
5.1.6 Performance characteristics . 38
5.2 Theory . 39
5.2.1 Seebeck effect . 39
5.2.2 Peltier effect . 40
5.2.3 Thomson effect . 40
5.2.4 Joule effect . 40
5.2.5 Fourier effect . 40
5.3 Space applications. 40
5.3.1 Electro-optics applications . 41
5.3.2 Fluid refrigeration . 41
5.3.3 Cooling of electronic equipment . 42
5.4 Existing systems . 42
5.4.2 Marlow Industries, Inc. . 42
5.4.3 Melcor . 45
Bibliography . 49
Figures
Figure 4-1: Temperature range of thermofoil heaters depending on insulation. From
MINCO (1989a) [6]. a) Kapton/FEP, b) Kapton/FEP Al backing, c) Nomex,
d) Silicone Rubber, e) Mica, f) Kapton/WA, g) Polyimide Glass, h)
Polyester, i) Scrim. . 13
Figure 4-2: Outgassing in a vacuum environment. Weight loss versus time.
−4
Temperature 473 K, pressure 4 x 10 Pa, preconditioning 50 % RH. From
MINCO (1973) [5]. : Cross-linked polyalkane; : Silicone
rubber, MIL-W-16878/7; : MIL-W-81044/1; : Kapton, Type HF. . 14
Figure 4-3: On/Off control. Temperature versus Time. From MINCO (1989a) [6]. . 18
Figure 4-4: Simple proportional control. Temperature versus Time. From MINCO
(1989a) [6]. . 19
Figure 4-5: Pattem of MINCO Standard. Thermofoil heaters. From MINCO (1989a) [6]. . 22
3
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Figure 4-6: Pattem of MINCO Mica. Thermofoil heaters. Dimensions in mm. From
MINCO (1989a) [6] . 22
Figure 4-7: Pattem of MINCO. Heater Kit HK913. From MINCO (1989a) [6] . 22
Figure 4-8: Clamping attachment of a MINCO Mica. Thermofoil heater. From MINCO
(1989a) [6]. . 24
Figure 4-9: Standard ISOPAD products. (a) ISOTAPE, (b) ISOTRACE and (c)
UNITRACE. From ISOPAD (1990) [2]. . 33
Figure 5-1: Schematic of a thermoelectric cooling element. From Scott (1974) [10]. . 36
Figure 5-2: Schematic of a typical thermoelectric module assembly. Elements
electrically in series and thermally in parallel. From Scott (1974) [10]. . 36
Figure 5-3: Maximum temperature difference versus number of stages in a module.
From MARLOW (1988) [3]. 37
Figure 5-4: Temperature distribution through a thermoelectric cooling unit. From Scott
(1974) [10]. . 38
Figure 5-5: Temperature difference across a typical thermoelectric cooling unit versus
heat pumped. From Scott (1974) [10]. . 39
Figure 5-6: Spacecraft thermal control using thermoelectric devices (TEDs). From
Chapter & Johnsen (1973) [1]. . 41
Figure 5-7: MELCOR Thermoelectric Heat Pump Module configurations. From
MELCOR (1987) [4] . 47
Tables
Table 4-1: Characteristics of MINCO Thermofoil Heaters. From MINCO (1989a) [6] . 20
Table 4-2: MINCO Standard Thermofoil Heaters. Kapton, silicone rubber and Nomex
insulations. From MINCO (1989a) [6] . 21
Table 4-3: MINCO Standard Thermofoil Heaters. Mica Insulation. From MINCO
(1989a) [6] . 21
Table 4-4: Area and Electrical Resistance of the Heaters Contained in Minco Heater Kit
HK913. From MINCO (1989a) [6] . 23
Table 4-5: Characteristics of Adhesives Recommended by MINCO. From MINCO
(1989c) [8] . 25
Table 4-6: Specifications of MINCO Thermofoil Heaters. From MINCO (1989a) [6] . 27
Table 4-7: Characteristics of MINCO Lead wires Mounted in Kapton, Nomex and
Silicone Rubber Heaters. From MINCO (1989a) [6] . 28
Table 4-8: Characteristics of MINCO Lead wires mounted in Mica Heaters. From
MINCO (1989a) [6] . 28
Table 4-9: Specifications of ISOPAD electrical heaters. From ISOPAD (1990) . 30
Table 5-1: Performance characteristics and dimensions of MARLOW Standard
Thermoelectric Coolers. From MARLOW (1988) [3]. . 44
Table 5-2: MELCOR Thermoelectric Heat Pump Module Specifications. FC Series.
From MELCOR (1987) [4] . 46
Table 5-3: MELCOR Thermoelectric Heat Pump Module Specifications. CP Series.
From MELCOR (1987) [4] . 47
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Table 5-4: MELCOR Wire Standards. From MELCOR (1987) [4] . 48
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European Foreword
This document (CEN/CLC/TR 17603-31-11:2021) has been prepared by Technical Committee
CEN/CLC/JTC 5 “Space”, the secretariat of which is held by DIN.
It is highlighted that this technical report does not contain any requirement but only collection of data
or descriptions and guidelines about how to organize and perform the work in support of EN 16603-
31.
This Technical report (TR 17603-31-11:2021) originates from ECSS-E-HB-31-01 Part 11A .
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such
patent rights.
This document has been prepared under a mandate given to CEN by the European Commission and
the European Free Trade Association.
This document has been developed to cover specifically space systems and has therefore precedence
over any TR covering the same scope but with a wider domain of applicability (e.g.: aerospace).
6
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1
Scope
In this Part 11, the use of electrical heaters and electrical coolers in spacecraft systems are described.
Electrical thermal control is an efficient and reliable method for attaining and maintaining
temperatures. Solid state systems provide for flexibility in control of thermal regulation, they are
resistant to shock and vibration and can operate in extreme physical conditions such as high and zero
gravity levels. They are also easy to integrate into spacecraft subsystems.
The Thermal design handbook is published in 16 Parts
TR 17603-31-01 Thermal design handbook – Part 1: View factors
TR 17603-31-02 Thermal design handbook – Part 2: Holes, Grooves and Cavities
TR 17603-31-03 Thermal design handbook – Part 3: Spacecraft Surface Temperature
TR 17603-31-04 Thermal design handbook – Part 4: Conductive Heat Transfer
TR 17603-31-05 Thermal design handbook – Part 5: Structural Materials: Metallic and
Composite
TR 17603-31-06 Thermal design handbook – Part 6: Thermal Control Surfaces
TR 17603-31-07 Thermal design handbook – Part 7: Insulations
TR 17603-31-08 Thermal design handbook – Part 8: Heat Pipes
TR 17603-31-09 Thermal design handbook – Part 9: Radiators
TR 17603-31-10 Thermal design handbook – Part 10: Phase – Change Capacitors
TR 17603-31-11 Thermal design handbook – Part 11: Electrical Heating
TR 17603-31-12 Thermal design handbook – Part 12: Louvers
TR 17603-31-13 Thermal design handbook – Part 13: Fluid Loops
TR 17603-31-14 Thermal design handbook – Part 14: Cryogenic Cooling
TR 17603-31-15 Thermal design handbook – Part 15: Existing Satellites
TR 17603-31-16 Thermal design handbook – Part 16: Thermal Protection System
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2
References
EN Reference Reference in text Title
EN 16601-00-01 ECSS-S-ST-00-01 ECSS System - Glossary of terms
EN 16603-31-15 ECSS-E-HB-31-01 Part 15 Thermal design handbook – Part 15: Existing
Satellites
All other references made to publications in this Part are listed, alphabetically, in the Bibliography.
8
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3
Terms, definitions and symbols
3.1 Terms and definitions
For the purpose of this Standard, the terms and definitions given in ECSS-S-ST-00-01 apply.
3.2 Symbols
2
cross sectional area, [m ]
A
electric current, [A]
I
length of conductive path, [m]
L
heat transfer rate, [W]
Q
fourier effect heat flow, [W]
QF
joule heat flow, [W]
QJ
peltier effect heat flow, [W]
QP
conduction loss, [W]
Qcd
operating heat, [W]
Qo
process heat transfer rate, [W]
Qp
radiation loss, [W]
Qr
steady state loss, [W]
Qsl
warm-up power, [W]
Qw
electrical resistance, [Ω]
R
ambient temperature, [K]
Ta
final temperature, [K]
Tf
initial temperature, [K]
Ti
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heat sink temperature, [K]
Ts
voltage, [V]
V
power, [W]
W
neat seebeck coefficient for two dissimilar materials,
a
− −
1 1
[W.K .A ]
− −
1 1
specific heat, [J.kg .K ]
cp
−
1
latent heat of fusion or vaporization, [J.kg ]
h
− −
1 1
thermal conductivity, [W.m .K ]
k
mass of material in each process load, [kg]
m
thomson effect heat flow per unit of conductor length,
qT
−
1
[W.m ]
cycle time for each load, [s]
t
desired warm-up time, [s]
tw
difference of temperature between two junctions
∆T
formed by dissimilar materials, [K]
seebeck effect open circuit potential difference, [V]
∆VS
ε emissivity of heat sink material
− − −
8 2 4
σ Stefan-Boltzmann constant = 5,6697 x 10 W.m .K
− −
1 1
τ Thomson coefficient, [W.K .A ]
Subscripts
cool
c
hot
h
maximum
max
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4
Electrical heating
4.1 General
Reliable long-term performance of most spacecraft components takes place at a specified temperature
range. The attainment of some temperature range requires, in many instances, the generation of heat
within the spacecraft. This involves simply turning up an electrical, chemical or nuclear heater.
When a local uniform heat source or a profiled heating area is needed, electrical heaters can provide it
efficiently due to their versatility. Some applications are reported later in this clause.
Electrical heaters are based on Ohm's and Joule's laws.
Ohm's law states that the steady electric current, I, flowing through an electrical conductor is
proportional to the constant voltage, V, and to the reciprocal of the electrical resistance of the
conductor, R:
I = V/R
According to Joule's law, the heat released per unit time, Q, by an electrical current, I, is equal to the
square of the electrical current, multiplied by the electrical resistance, R:
2
Q = I R
Three parts can be distinguished in an electrical heater:
4.1.1 Conductive element
Made up by a metal alloy with specific properties depending on the use:
High-strength alloys to carry mechanical stress.
Non-magnetic materials.
High temperature-coefficient alloys for self-regulated heaters.
4.1.2 Electrical terminations
Depending on the objectives and operating conditions of the heater, the most widely used options are:
Welded leadwire
Crimped leadwire
High-temperature wire
UL-approved wire
Solder pads
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Pins and connectors
Plated through-holes
Integral flex-circuits
Flat foil leads
4.1.3 Electrical insulation
4.1.3.1 Kapton/FEP insulation
For temperature requirements less than 473 K, heaters constructed of Kapton film and FEP Teflon
have been qualified (NASA S-311-79) and flight tested for space. The Kapton film used generally is
− −
3 1
0,05 x 10 m thick, with a thermal conductivity of 163 W.m . It is used either onboard spacecraft or
for simulation purposes in ground experiments. It has good flexibility and light weight; it is chemical
6
and radiation resistant (to 10 rads) and present low outgassing. See Taylor (1984) [11].
Two types of Kapton laminated heater elements are manufactured:
4 2
Coiled wire is used for resistances up to 620 x 10Ω/m . It withstands severe flexing with
repeated installations and removals, because flexing does not bend the wire as it does to a
printed circuit.
Printed circuit Kapton/FEP heater is an etched nickel alloy foil with a clear amber
pollyimide insulation. It can be quite complex, with cutouts, void areas, and unusual
shapes. Varied watt densities within the same element can be obtained by controlling the
pattern.
It is the right choice for flat surfaces because heat is more efficiently transferred and, also, the foil
heater can be reproduced with great precision by photographic techniques. This kind of heaters has
been widely used in space applications.
Higher watt densities and greater reliability can be obtained with an aluminium foil backing: it
spreads heat and eliminates hot spots due to voids in mounting adhesives.
4.1.3.2 Other insulations
Electrical heaters working in hard conditions, like temperatures over 473 K, are sheathed in metal.
Alumina insulation is used to encase a spiral-wound or a straight wire resistance element within the
sheath. Moisture is removed and the enclosure is helium leak tested. Electrical connections are made
through a glass-to-metal seal header.
There are other kinds of foil heaters, with different insulations, but their usefulness in space
applications is limited. Nevertheless, they are mentioned here:
Nomex heaters are used as a low cost alternative to Kapton. It is radiation resistant to 106
rads, but it is not suitable for vacuum.
Silicone rubber is a fiberglass reinforced elastomer, it may be vulcanized to heat sinks
and it is resistant to many chemicals but it is not suitable for vacuum or radiation. It is
used for commercial and industrial applications because of its low cost and high
temperature rating compared to Kapton.
Mica heaters are rigid, so they should be factory formed and are clamped to heat sinks
with rigid backing plates, or else their layers will separate during warm-up. They can be
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used in vacuum after burn in. They can withstand temperatures up to 866 K, and high
3 −
1
watt densities, up to 1705 x 10 W.m .
Kapton/WA is a clear amber polyimide film with acrylic adhesive. It is chemical and
radiation resistant, with low outgassing, low cost and high resistance densities. The only
problem is its narrow temperature range that limits applications over 423 K.
Polyimide glass (Fiberglass reinforced polyimide) heaters have reduced flexibility but
they have a temperature range up to 513 K and a potential for high watt densities.
Optical grade polyester heaters have an 82 % light transmission and could be mounted in
windows, lenses or between LCD and backlight, in cockpit displays and handheld
terminals, in order to prevent condensation and permit cold weather operation.
Polyester is a low cost solution for economic fabrication of large heaters.
Scrim is an open weave fiberglass cloth for lamination inside composite structures.
Temperature range for some insulations, compared to Kapton/FEP, are represented in Figure 4-1.
Figure 4-1: Temperature range of thermofoil heaters depending on insulation.
From MINCO (1989a) [6]. a) Kapton/FEP, b) Kapton/FEP Al backing, c) Nomex, d)
Silicone Rubber, e) Mica, f) Kapton/WA, g) Polyimide Glass, h) Polyester, i) Scrim.
4.1.4 Outgassing
Outgassing in a vacuum environment, in terms of weight loss versus time is an important property in
space applications, see Figure 4-2. Essentially the outgassing products are water, carbon monoxide
and carbon dioxide. Loss weight in Kapton/FEP is very low, about 1 %, and it occurs during the first
few hours of test.
13
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Figure 4-2: Outgassing in a vacuum environment. Weight loss versus time.
−4
Temperature 473 K, pressure 4 x 10 Pa, preconditioning 50 % RH. From MINCO
(1973) [5]. : Cross-linked polyalkane; : Silicone rubber, MIL-W-16878/7;
: MIL-W-81044/1; : Kapton, Type HF.
4.2 Space applications
Electrical heaters have had a widespread gamut of uses. Some of them are mentioned in this clause.
4.2.1 Viking spacecraft
Thermostatically controlled electric heaters were used in the lander body to:
- Maintain the propulsion systems over hydrazine freezing point (275 K) and, at the same time,
maintain the cavity around the lander body at a relatively low temperature to prevent overheating of
the lander internal equipment during the pre-separation checkout operation.
Accurate temperature control in critical parts of the biology and gas chromatograph/mass
spectrometer experiments.
Pyrolyze Martian soil samples.
Heat external meteorology instruments and semi-external but insulated cameras.
From Tracey, Morey and Gorman (1978) [12].
4.2.2 Fltsatcom spacecraft
This satellite is essentially a constant power dissipation spacecraft, therefore this dissipation is
produced by the electronic units within the spacecraft and sufficient heaters are provided to substitute
for each component which might be turned off and maintain temperatures above established
minimum levels.
From Reeves (1979) [9].
4.2.3 OTS
Electrical heaters are used as battery heaters, in the Traveling Wave Tube Amplifier as compensation
heaters, and in the hydrazine tank, lines and valves, in order to prevent hydrazine from freezing.
See ECSS-E-HB-31-01 Part 15, clause 5.
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4.2.4 SPOT
Electrical heaters are used in the thermal control of the satellite platform, propulsion system, batteries
compartment, high-resolution visible range instruments, and payload telemetry system.
See ECSS-E-HB-31-01 Part 15, clause 8.
4.2.5 Miscellaneous utilization
To warm overboard dump valves for liquids (Space Shuttle).
To keep constant structural temperature on the Space Telescope in order to prevent
optical misalignment.
To maintain the temperature of sensitive gyroscopes and accelerometer guidance
platforms.
To control the temperature of pressure transducers, other electronics components, and
infrared reference sources.
Metal sheathed heaters are used on catalyst beds of hydrazine thruster engines for
spacecraft attitude control.
To prevent condensation on satellites viewing windows.
To keep solar panels warm at night.
As shunt resistors, mounted on the skin of a satellite, to dump excess power of
overcharged batteries which would otherwise overheat delicate instruments.
From Taylor (1984) [11].
4.3 Power requirement estimation
The design of electrical heaters for space presents one important characteristic: limited power makes
calculation of correct wattage become critical.
Calculation and theory cannot substitute for experimentation when accuracy is very important,
because they cannot account for all the variables acting upon the system; nevertheless the value
obtained with the quick estimation procedure that will be described here (MINCO (1989b) [7]), can be
used to obtain a first approximation.
To confirm wattage calculations, a sample heater is placed with the required configuration against an
actual or simulated component with thermocouples mounted. The expected environment is
reproduced and the voltage varied in order to find either heat-up time or the exact power required for
temperature stabilization.
Finite element analysis can handle many problems which resist theoretical or experimental solutions.
It is able to simulate extremely fast warm-ups, map thermal gradients across complex shapes, and
determine watt density zones for profiled heaters.
When the warm-up heat is much greater than the steady state loss (a common situation) a dual
element heater may be a good solution: one high-power element for warm-up and a smaller element
for maintenance temperature.
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CEN/CLC/TR 17603-3
...
SLOVENSKI STANDARD
kSIST-TP FprCEN/CLC/TR 17603-31-11:2021
01-maj-2021
Vesoljska tehnika - Priročnik za toplotno zasnovo - 11. del: Električno ogrevanje
Space engineering - Thermal design handbook - Part 11: Electrical Heating
Raumfahrttechnik - Handbuch für thermisches Design - Teil 11: Elektrisches Heizen
Ingénierie spatiale - Manuel de conception thermique - Partie 11: Chauffage électrique
Ta slovenski standard je istoveten z: FprCEN/CLC/TR 17603-31-11
ICS:
49.140 Vesoljski sistemi in operacije Space systems and
operations
kSIST-TP FprCEN/CLC/TR 17603-31- en,fr,de
11:2021
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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TECHNICAL REPORT
FINAL DRAFT
FprCEN/CLC/TR 17603-
RAPPORT TECHNIQUE
31-11
TECHNISCHER BERICHT
February 2021
ICS 49.140
English version
Space engineering - Thermal design handbook - Part 11:
Electrical Heating
Ingénierie spatiale - Manuel de conception thermique - Raumfahrttechnik - Handbuch für thermisches Design -
Partie 11: Chauffage électrique Teil 11: Elektrisches Heizen
This draft Technical Report is submitted to CEN members for Vote. It has been drawn up by the Technical Committee
CEN/CLC/JTC 5.
CEN and CENELEC members are the national standards bodies and national electrotechnical committees of Austria, Belgium,
Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
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Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and United Kingdom.
Recipients of this draft are invited to submit, with their comments, notification of any relevant patent rights of which they are
aware and to provide supporting documentation.
Warning : This document is not a Technical Report. It is distributed for review and comments. It is subject to change without
notice and shall not be referred to as a Technical Report.
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© 2021 CEN/CENELEC All rights of exploitation in any form and by any means Ref. No. FprCEN/CLC/TR 17603-31-11:2021 E
reserved worldwide for CEN national Members and for
CENELEC Members.
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Table of contents
European Foreword . 6
1 Scope . 7
2 References . 8
3 Terms, definitions and symbols . 9
3.1 Terms and definitions . 9
3.2 Symbols . 9
4 Electrical heating . 11
4.1 General . 11
4.1.1 Conductive element . 11
4.1.2 Electrical terminations . 11
4.1.3 Electrical insulation . 12
4.1.4 Outgassing . 13
4.2 Space applications. 14
4.2.1 Viking spacecraft . 14
4.2.2 Fltsatcom spacecraft . 14
4.2.3 OTS . 14
4.2.4 SPOT . 15
4.2.5 Miscellaneous utilization . 15
4.3 Power requirement estimation . 15
4.3.1 Simplification assumptions . 16
4.3.2 Conduction losses . 16
4.3.3 Radiation losses . 16
4.3.4 Process heat requirements . 16
4.3.5 Operating heat requirements . 16
4.3.6 Warm-up heat requirements . 17
4.4 Regulation of electrical heaters . 17
4.4.1 Temperature sensor . 18
4.4.2 Temperature controller . 18
4.5 Existing systems . 19
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4.5.1 Minco Products Inc. . 19
4.5.2 Isopad Limited . 28
5 Electrical cooling . 35
5.1 General . 35
5.1.1 Description . 35
5.1.2 Advantages of use . 35
5.1.3 Physical phenomena . 35
5.1.4 Multi-stage thermoelectric devices . 36
5.1.5 Heat dissipation . 37
5.1.6 Performance characteristics . 38
5.2 Theory . 39
5.2.1 Seebeck effect . 39
5.2.2 Peltier effect . 40
5.2.3 Thomson effect . 40
5.2.4 Joule effect . 40
5.2.5 Fourier effect . 40
5.3 Space applications. 40
5.3.1 Electro-optics applications . 41
5.3.2 Fluid refrigeration . 41
5.3.3 Cooling of electronic equipment . 42
5.4 Existing systems . 42
5.4.2 Marlow Industries, Inc. . 42
5.4.3 Melcor . 45
Bibliography . 49
Figures
Figure 4-1: Temperature range of thermofoil heaters depending on insulation. From
MINCO (1989a) [6]. a) Kapton/FEP, b) Kapton/FEP Al backing, c) Nomex,
d) Silicone Rubber, e) Mica, f) Kapton/WA, g) Polyimide Glass, h)
Polyester, i) Scrim. . 13
Figure 4-2: Outgassing in a vacuum environment. Weight loss versus time.
4
Temperature 473 K, pressure 4 x 10 Pa, preconditioning 50 % RH. From
MINCO (1973) [5]. : Cross-linked polyalkane; : Silicone
rubber, MIL-W-16878/7; : MIL-W-81044/1; : Kapton, Type HF. . 14
Figure 4-3: On/Off control. Temperature versus Time. From MINCO (1989a) [6]. . 18
Figure 4-4: Simple proportional control. Temperature versus Time. From MINCO
(1989a) [6]. . 19
Figure 4-5: Pattem of MINCO Standard. Thermofoil heaters. From MINCO (1989a) [6]. . 22
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Figure 4-6: Pattem of MINCO Mica. Thermofoil heaters. Dimensions in mm. From
MINCO (1989a) [6] . 22
Figure 4-7: Pattem of MINCO. Heater Kit HK913. From MINCO (1989a) [6] . 22
Figure 4-8: Clamping attachment of a MINCO Mica. Thermofoil heater. From MINCO
(1989a) [6]. . 24
Figure 4-9: Standard ISOPAD products. (a) ISOTAPE, (b) ISOTRACE and (c)
UNITRACE. From ISOPAD (1990) [2]. . 33
Figure 5-1: Schematic of a thermoelectric cooling element. From Scott (1974) [10]. . 36
Figure 5-2: Schematic of a typical thermoelectric module assembly. Elements
electrically in series and thermally in parallel. From Scott (1974) [10]. . 36
Figure 5-3: Maximum temperature difference versus number of stages in a module.
From MARLOW (1988) [3]. 37
Figure 5-4: Temperature distribution through a thermoelectric cooling unit. From Scott
(1974) [10]. . 38
Figure 5-5: Temperature difference across a typical thermoelectric cooling unit versus
heat pumped. From Scott (1974) [10]. . 39
Figure 5-6: Spacecraft thermal control using thermoelectric devices (TEDs). From
Chapter & Johnsen (1973) [1]. . 41
Figure 5-7: MELCOR Thermoelectric Heat Pump Module configurations. From
MELCOR (1987) [4] . 47
Tables
Table 4-1: Characteristics of MINCO Thermofoil Heaters. From MINCO (1989a) [6] . 20
Table 4-2: MINCO Standard Thermofoil Heaters. Kapton, silicone rubber and Nomex
insulations. From MINCO (1989a) [6] . 21
Table 4-3: MINCO Standard Thermofoil Heaters. Mica Insulation. From MINCO
(1989a) [6] . 21
Table 4-4: Area and Electrical Resistance of the Heaters Contained in Minco Heater Kit
HK913. From MINCO (1989a) [6] . 23
Table 4-5: Characteristics of Adhesives Recommended by MINCO. From MINCO
(1989c) [8] . 25
Table 4-6: Specifications of MINCO Thermofoil Heaters. From MINCO (1989a) [6] . 27
Table 4-7: Characteristics of MINCO Lead wires Mounted in Kapton, Nomex and
Silicone Rubber Heaters. From MINCO (1989a) [6] . 28
Table 4-8: Characteristics of MINCO Lead wires mounted in Mica Heaters. From
MINCO (1989a) [6] . 28
Table 4-9: Specifications of ISOPAD electrical heaters. From ISOPAD (1990) . 30
Table 5-1: Performance characteristics and dimensions of MARLOW Standard
Thermoelectric Coolers. From MARLOW (1988) [3]. . 44
Table 5-2: MELCOR Thermoelectric Heat Pump Module Specifications. FC Series.
From MELCOR (1987) [4] . 46
Table 5-3: MELCOR Thermoelectric Heat Pump Module Specifications. CP Series.
From MELCOR (1987) [4] . 47
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Table 5-4: MELCOR Wire Standards. From MELCOR (1987) [4] . 48
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European Foreword
This document (FprCEN/CLC/TR 17603-31-11:2021) has been prepared by Technical Committee
CEN/CLC/JTC 5 “Space”, the secretariat of which is held by DIN.
This document is currently submitted to the Vote on TR.
It is highlighted that this technical report does not contain any requirement but only collection of data
or descriptions and guidelines about how to organize and perform the work in support of EN 16603-
31.
This Technical report (FprCEN/CLC/TR 17603-31-11:2021) originates from ECSS-E-HB-31-01 Part 11A .
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such
patent rights.
This document has been prepared under a mandate given to CEN by the European Commission and
the European Free Trade Association.
This document has been developed to cover specifically space systems and has therefore precedence
over any TR covering the same scope but with a wider domain of applicability (e.g.: aerospace).
This document is currently submitted to the CEN CONSULTATION.
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1
Scope
In this Part 11, the use of electrical heaters and electrical coolers in spacecraft systems are described.
Electrical thermal control is an efficient and reliable method for attaining and maintaining
temperatures. Solid state systems provide for flexibility in control of thermal regulation, they are
resistant to shock and vibration and can operate in extreme physical conditions such as high and zero
gravity levels. They are also easy to integrate into spacecraft subsystems.
The Thermal design handbook is published in 16 Parts
TR 17603-31-01 Thermal design handbook – Part 1: View factors
TR 17603-31-02 Thermal design handbook – Part 2: Holes, Grooves and Cavities
TR 17603-31-03 Thermal design handbook – Part 3: Spacecraft Surface Temperature
TR 17603-31-04 Thermal design handbook – Part 4: Conductive Heat Transfer
TR 17603-31-05 Thermal design handbook – Part 5: Structural Materials: Metallic and
Composite
TR 17603-31-06 Thermal design handbook – Part 6: Thermal Control Surfaces
TR 17603-31-07 Thermal design handbook – Part 7: Insulations
TR 17603-31-08 Thermal design handbook – Part 8: Heat Pipes
TR 17603-31-09 Thermal design handbook – Part 9: Radiators
TR 17603-31-10 Thermal design handbook – Part 10: Phase – Change Capacitors
TR 17603-31-11 Thermal design handbook – Part 11: Electrical Heating
TR 17603-31-12 Thermal design handbook – Part 12: Louvers
TR 17603-31-13 Thermal design handbook – Part 13: Fluid Loops
TR 17603-31-14 Thermal design handbook – Part 14: Cryogenic Cooling
TR 17603-31-15 Thermal design handbook – Part 15: Existing Satellites
TR 17603-31-16 Thermal design handbook – Part 16: Thermal Protection System
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2
References
EN Reference Reference in text Title
EN 16601-00-01 ECSS-S-ST-00-01 ECSS System - Glossary of terms
EN 16603-31-15 ECSS-E-HB-31-01 Part 15 Thermal design handbook – Part 15: Existing
Satellites
All other references made to publications in this Part are listed, alphabetically, in the Bibliography.
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3
Terms, definitions and symbols
3.1 Terms and definitions
For the purpose of this Standard, the terms and definitions given in ECSS-S-ST-00-01 apply.
3.2 Symbols
2
cross sectional area, [m ]
A
electric current, [A]
I
length of conductive path, [m]
L
heat transfer rate, [W]
Q
fourier effect heat flow, [W]
QF
joule heat flow, [W]
QJ
peltier effect heat flow, [W]
QP
conduction loss, [W]
Qcd
operating heat, [W]
Qo
process heat transfer rate, [W]
Qp
radiation loss, [W]
Qr
steady state loss, [W]
Qsl
warm-up power, [W]
Qw
electrical resistance, []
R
ambient temperature, [K]
Ta
final temperature, [K]
Tf
initial temperature, [K]
Ti
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heat sink temperature, [K]
Ts
voltage, [V]
V
power, [W]
W
neat seebeck coefficient for two dissimilar materials,
a
1 1
[W.K .A ]
1 1
specific heat, [J.kg .K ]
cp
1
latent heat of fusion or vaporization, [J.kg ]
h
1 1
thermal conductivity, [W.m .K ]
k
mass of material in each process load, [kg]
m
thomson effect heat flow per unit of conductor length,
qT
1
[W.m ]
cycle time for each load, [s]
t
desired warm-up time, [s]
tw
difference of temperature between two junctions
T
formed by dissimilar materials, [K]
seebeck effect open circuit potential difference, [V]
VS
emissivity of heat sink material
8 2 4
Stefan-Boltzmann constant = 5,6697 x 10 W.m .K
1 1
Thomson coefficient, [W.K .A ]
Subscripts
cool
c
hot
h
maximum
max
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4
Electrical heating
4.1 General
Reliable long-term performance of most spacecraft components takes place at a specified temperature
range. The attainment of some temperature range requires, in many instances, the generation of heat
within the spacecraft. This involves simply turning up an electrical, chemical or nuclear heater.
When a local uniform heat source or a profiled heating area is needed, electrical heaters can provide it
efficiently due to their versatility. Some applications are reported later in this clause.
Electrical heaters are based on Ohm's and Joule's laws.
Ohm's law states that the steady electric current, I, flowing through an electrical conductor is
proportional to the constant voltage, V, and to the reciprocal of the electrical resistance of the
conductor, R:
I = V/R
According to Joule's law, the heat released per unit time, Q, by an electrical current, I, is equal to the
square of the electrical current, multiplied by the electrical resistance, R:
2
Q = I R
Three parts can be distinguished in an electrical heater:
4.1.1 Conductive element
Made up by a metal alloy with specific properties depending on the use:
High-strength alloys to carry mechanical stress.
Non-magnetic materials.
High temperature-coefficient alloys for self-regulated heaters.
4.1.2 Electrical terminations
Depending on the objectives and operating conditions of the heater, the most widely used options are:
Welded leadwire
Crimped leadwire
High-temperature wire
UL-approved wire
Solder pads
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Pins and connectors
Plated through-holes
Integral flex-circuits
Flat foil leads
4.1.3 Electrical insulation
4.1.3.1 Kapton/FEP insulation
For temperature requirements less than 473 K, heaters constructed of Kapton film and FEP Teflon
have been qualified (NASA S-311-79) and flight tested for space. The Kapton film used generally is
3 1
0,05 x 10 m thick, with a thermal conductivity of 163 W.m . It is used either onboard spacecraft or
for simulation purposes in ground experiments. It has good flexibility and light weight; it is chemical
and radiation resistant (to 10 rads) and present low outgassing. See Taylor (1984) [11].
Two types of Kapton laminated heater elements are manufactured:
Coiled wire is used for resistances up to 620 x 10 /m . It withstands severe flexing with
repeated installations and removals, because flexing does not bend the wire as it does to a
printed circuit.
Printed circuit Kapton/FEP heater is an etched nickel alloy foil with a clear amber
pollyimide insulation. It can be quite complex, with cutouts, void areas, and unusual
shapes. Varied watt densities within the same element can be obtained by controlling the
pattern.
It is the right choice for flat surfaces because heat is more efficiently transferred and, also, the foil
heater can be reproduced with great precision by photographic techniques. This kind of heaters has
been widely used in space applications.
Higher watt densities and greater reliability can be obtained with an aluminium foil backing: it
spreads heat and eliminates hot spots due to voids in mounting adhesives.
4.1.3.2 Other insulations
Electrical heaters working in hard conditions, like temperatures over 473 K, are sheathed in metal.
Alumina insulation is used to encase a spiral-wound or a straight wire resistance element within the
sheath. Moisture is removed and the enclosure is helium leak tested. Electrical connections are made
through a glass-to-metal seal header.
There are other kinds of foil heaters, with different insulations, but their usefulness in space
applications is limited. Nevertheless, they are mentioned here:
Nomex heaters are used as a low cost alternative to Kapton. It is radiation resistant to 106
rads, but it is not suitable for vacuum.
Silicone rubber is a fiberglass reinforced elastomer, it may be vulcanized to heat sinks
and it is resistant to many chemicals but it is not suitable for vacuum or radiation. It is
used for commercial and industrial applications because of its low cost and high
temperature rating compared to Kapton.
Mica heaters are rigid, so they should be factory formed and are clamped to heat sinks
with rigid backing plates, or else their layers will separate during warm-up. They can be
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used in vacuum after burn in. They can withstand temperatures up to 866 K, and high
1
watt densities, up to 1705 x 10 W.m .
Kapton/WA is a clear amber polyimide film with acrylic adhesive. It is chemical and
radiation resistant, with low outgassing, low cost and high resistance densities. The only
problem is its narrow temperature range that limits applications over 423 K.
Polyimide glass (Fiberglass reinforced polyimide) heaters have reduced flexibility but
they have a temperature range up to 513 K and a potential for high watt densities.
Optical grade polyester heaters have an 82 % light transmission and could be mounted in
windows, lenses or between LCD and backlight, in cockpit displays and handheld
terminals, in order to prevent condensation and permit cold weather operation.
Polyester is a low cost solution for economic fabrication of large heaters.
Scrim is an open weave fiberglass cloth for lamination inside composite structures.
Temperature range for some insulations, compared to Kapton/FEP, are represented in Figure 4-1.
Figure 4-1: Temperature range of thermofoil heaters depending on insulation.
From MINCO (1989a) [6]. a) Kapton/FEP, b) Kapton/FEP Al backing, c) Nomex, d)
Silicone Rubber, e) Mica, f) Kapton/WA, g) Polyimide Glass, h) Polyester, i) Scrim.
4.1.4 Outgassing
Outgassing in a vacuum environment, in terms of weight loss versus time is an important property in
space applications, see Figure 4-2. Essentially the outgassing products are water, carbon monoxide
and carbon dioxide. Loss weight in Kapton/FEP is very low, about 1 %, and it occurs during the first
few hours of test.
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Figure 4-2: Outgassing in a vacuum environment. Weight loss versus time.
4
Temperature 473 K, pressure 4 x 10 Pa, preconditioning 50 % RH. From MINCO
(1973) [5]. : Cross-linked polyalkane; : Silicone rubber, MIL-W-16878/7;
: MIL-W-81044/1; : Kapton, Type HF.
4.2 Space applications
Electrical heaters have had a widespread gamut of uses. Some of them are mentioned in this clause.
4.2.1 Viking spacecraft
Thermostatically controlled electric heaters were used in the lander body to:
- Maintain the propulsion systems over hydrazine freezing point (275 K) and, at the same time,
maintain the cavity around the lander body at a relatively low temperature to prevent overheating of
the lander internal equipment during the pre-separation checkout operation.
Accurate temperature control in critical parts of the biology and gas chromatograph/mass
spectrometer experiments.
Pyrolyze Martian soil samples.
Heat external meteorology instruments and semi-external but insulated cameras.
From Tracey, Morey and Gorman (1978) [12].
4.2.2 Fltsatcom spacecraft
This satellite is essentially a constant power dissipation spacecraft, therefore this dissipation is
produced by the electronic units within the spacecraft and sufficient heaters are provided to substitute
for each component which might be turned off and maintain temperatures above established
minimum levels.
From Reeves (1979) [9].
4.2.3 OTS
Electrical heaters are used as battery heaters, in the Traveling Wave Tube Amplifier as compensation
heaters, and in the hydrazine tank, lines and valves, in order to prevent hydrazine from freezing.
See ECSS-E-HB-31-01 Part 15, clause 5.
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4.2.4 SPOT
Electrical heaters are used in the thermal control of the satellite platform, propulsion system, batteries
compartment, high-resolution visible range instruments, and payload telemetry system.
See ECSS-E-HB-31-01 Part 15, clause 8.
4.2.5 Miscellaneous utilization
To warm overboard dump valves for liquids (Space Shuttle).
To keep constant structural temperature on the Space Telescope in order to prevent
optical misalignment.
To maintain the temperature of sensitive gyroscopes and accelerometer guidance
platforms.
To control the temperature of pressure transducers, other electronics components, and
infrared reference sources.
Metal sheathed heaters are used on catalyst beds of hydrazine thruster engines for
spacecraft attitude control.
To prevent condensation on satellites viewing windows.
To keep solar panels warm at night.
As shunt resistors, mounted on the skin of a satellite, to dump excess power of
overcharged batteries which would otherwise overheat delicate instruments.
From Taylor (1984) [11].
4.3 Power requirement estimation
The design of electrical heaters for space presents one important characteristic: limited power makes
calculation of correct wattage become critical.
Calculation and theory cannot substitute for experimentation when accuracy is very important,
because they cannot account for all the variables acting upon the system; nevertheless the value
obtained with the quick estimation procedure that will be described here (MINCO (1989b) [7]), can be
used to obtain a first approximation.
To confirm wattage calculations, a sample heater is placed with the required configuration against an
actual or simulated component with thermocouples mounted. The expected environment is
reproduced and the voltage varied in order to find either heat-up time or the exact power
...
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