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This specification replaces GJB 2703-1996 General specification of thermal control system for satellite.
The following main changes have been made with respect to GJB 2703-1996 General specification of thermal control system for satellite:
a) the name of the specification is changed as General specification for thermal control system for spacecrafts, and the application scope is expanded from "satellites" in the original specification to "spacecrafts", including satellites, airships, space stations and deep space probes;
b) in Clause 3 "Requirements", the "detailed specifications" and "qualification appraisal” in the original specification are canceled according to GJB 0 Directives for formulating military standardization documents. Clause 3 of this specification consists of 18 subclauses such as "Missions", "System composition", "Design" and "Performance";
c) 3.1 "Missions" of this specification is a new subclause;
d) compared with the original specification, products such as "temperature sensors", "humidity sensors", "refrigerators", "thermal switches", "humidity control devices", "THERMON", "thermal radiators", "loop heat pipes", "capillary pumped loops", “fluid loops", "ventilation loops", “isotope heat sources” and “thermal control software” are added in 3.2 "System composition" of this specification;
e) compared with the original specification, the relevant requirements such as "functional characteristics" and "thermal uncertainty margin” are added in 3.3 "Design" of this specification;
f) compared with the original specification, the performance requirements such as "temperature uniformity", "humidity" and "air flow (velocity)" are added in 3.4 "Performance" of this specification;
g) compared with the original specification, the relevant requirements of "interface with spacecraft assembly", "mechanical interface" and "electrical interface” are supplemented in 3.17 "Interface" of this specification.
h) with the development of technology, the variety of thermal control system products has more than doubled in recent years, so it is difficult to describe all kinds of thermal control system products and their performances clearly in this specification. Therefore, ten thermal control system products and their main performance in 3.14 "Thermal control materials, components and devices" of the original specification are canceled in this specification, and the performance requirements and application principles for thermal control system products are put forward in 3.18 "Thermal control system products" of this specification.
This specification was proposed by the Electronic Information Base Department of the General Armaments Department of the PLA.
This standard is under the jurisdiction of the Aerospace Equipment Research and Development Center of the General Armaments Department of the PLA.
GJB 2703-1996 General specification of thermal control system for satellite was issued in June 1996 for the first time, and this is the first revision.
General specification for thermal control system for spacecrafts
1 Scope
This specification specifies the general requirements for thermal control system for spacecrafts.
This specification is applicable to the thermal control system for spacecrafts such as satellites, airships, space stations and deep space probes.
2 Normative references
The following normative documents contain provisions which, through reference in this text, constitute provisions of this specification. For dated reference, subsequent amendments (excluding corrections), or revisions, of any of these publications do not apply to this specification. However parties to agreements based on this specification are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references or references with version not indicated, the latest edition of the normative document referred to applies.
GJB 151 Electromagnetic emission and susceptibility requirements for military equipment and subsystems
GJB 152 Measurement of electromagnetic emission and susceptibility requirements for military equipment and subsystems
GJB 1027 Environmental test requirements for satellites
GJB 1033 Method for thermal balance of satellites
GJB 1197 Acoustic test method for satellites
GJB 2204 General specification for satellite integration
QJ 1579 Vibration test method for whole satellite
QJ 1840 Satellite mass distribution
QJ 3169 Distribution criterion for spacecraft electrical power
3 Requirements
3.1 Missions
The missions of the thermal control system is to control the exchange of heat inside and outside the spacecraft with various possible methods under given constraints, so that the thermal parameters of the spacecraft and the products installed on it, such as temperature, humidity and air flow (velocity), and other related performance indicators can meet the requirements of the contract (or assignment).
3.2 System composition
Thermal control system is usually composed of thermal control hardware and thermal control software. Hardware products mainly include thermal control coatings, thermal insulation units, thermal conductive fillers, thermal insulation gaskets, thermal diffusion plates, thermal conductive cables, temperature sensors, humidity sensors, heat pipes, electric heaters, refrigerators, thermal switches, humidity control devices, phase change heat storage devices, louvers, THERMON, thermal radiators, thermal control units, loop heat pipes, capillary pumped loops, fluid loops, ventilation loops, isotope heat sources, etc.
3.3 Design
3.3.1 Functional characteristics
The thermal control system shall have the following functional characteristics:
a) control spacecraft to absorb heat flow from external environment and discharged to cryogenic space;
b) realize the collection, diffusion and transmission of heat flow of spacecraft and its products, and control the transmission path and direction of heat flow;
c) store the heat energy of spacecraft and its products, and release them where necessary;
d) control the temperature range, difference, gradient, stability and uniformity of spacecraft products;
e) adjust the humidity of the air in the sealed cabin of spacecraft;
f) control the air flow (velocity) in the sealed cabin.
3.3.2 Control mode
In order to realize functional characteristics, the thermal parameters are usually controlled in the following three ways:
a) passive thermal control, namely the control without the need of the signal feedback of controlled objects. In passive thermal control, there are usually no moving components, no or less power is consumed, providing a high reliability;
b) active thermal control, namely the automatic adjustment of thermal parameters relying on the signal feedback function of the controlled objects. Active thermal control has great adjusting ability or high control accuracy, but it has the disadvantages of complex technology and high cost, and its reliability is lower than that of passive thermal control;
c) a hybrid control mode combining passive thermal control and active thermal control.
3.3.3 Thermal uncertainty margin
Thermal uncertainty margin shall meet the following requirements:
a) for spacecraft products in passive thermal control mode, the thermal uncertainty margin is generally 11℃ after the correlation verification of spacecraft thermal analysis model by thermal balance test, and the thermal uncertainty margin of mature long-life geosynchronous orbit spacecraft products shall not be less than 5℃;
b) for spacecraft products in passive thermal control mode, the thermal uncertainty margin is generally 17℃ before or without the correlation verification of spacecraft thermal analysis model by thermal balance test. If the thermal uncertainty margin of 17℃ significantly increases the weight and power of spacecraft, it may be reduced to 11℃;
c) for spacecraft products in passive thermal control that work below -70℃, the thermal uncertainty margin may be determined according to the values in Table 1;
Table 1 Thermal uncertainty margin of products in passive thermal control In ℃
d) for the design of active thermal control by electric heating, the heater power shall have a margin of 25% as the thermal uncertainty margin. For example, the actual average power consumption of a proportional (or PID-controlled) heater with a rated power of 100W shall not be greater than 80W; if a switch-controlled heater is used, its duty ratio shall not exceed 80%;
e) for temperature sensitive equipment with temperature control circuit, such as storage battery, gyro, precision clock, camera, etc., the thermal uncertainty margin shall be the power margin of the heater for temperature control, instead of adding temperature margin according to a);
f) for products in active control with a temperature lower than -70℃, the uncertainty margin of thermal load shall not be less than 50%, 45% and 35% in the scheme phase, prototype development phase and flight model development phase respectively;
g) deep space probes shall have greater thermal uncertainty margin;
h) the control ability of humidity and air flow (velocity) shall also have appropriate margin.
3.4 Performance
3.4.1 General
The specific performance indicator of thermal control system for spacecraft shall be specified in the model specification according to the actual situation of the model and with reference to the requirements of this subclause. The performance of thermal control system mainly includes:
a) temperature, including temperature range, difference, gradient, stability and uniformity;
b) humidity;
c) air flow (velocity).
3.4.2 Temperature
The temperature of spacecraft and its products shall meet the following requirements:
a) the minimum temperature of spacecraft and its products in worst cold case and the maximum temperature in worst hot case shall meet the requirements of design temperature range;
b) the design temperature range of spacecraft products is verified and assessed by the temperature value of the temperature reference point;
c) where necessary, the following parameters and their design values shall also meet the requirements of special technical conditions:
1) maximum and minimum temperature difference;
2) maximum and minimum temperature gradient;
3) maximum and minimum temperature stability;
4) maximum and minimum temperature uniformity.
3.4.3 Humidity
The maximum and minimum design humidity in the sealed cabin of spacecraft shall meet the requirements of special technical specifications.
3.4.4 Air flow (velocity)
The maximum and minimum design air flow (velocity) in the sealed cabin of spacecraft shall meet the requirements of special technical specifications.
3.5 Weight
The weight of thermal control system shall meet the following requirements:
a) for satellites with a total weight not greater than 500kg, the weight of thermal control system shall generally not be greater than 6% of the total weight. For satellites with a total weight greater than 500kg, the weight of the thermal control system shall generally not be greater than 4% of the total weight; for different types of satellites, this value may be determined with reference to the relevant requirements of QJ 1840;
b) the weight of thermal control system for airship shall generally not be greater than 6% of the total weight;
c) the weight of thermal control system for space station generally is generally 7%~12% of the total weight;
d) the weight of thermal control system for deep space probe may be determined with reference to the relevant requirements of QJ 1840.
3.6 Power consumption
The power consumption of thermal control system shall meet the following requirements:
a) for satellites with long-term power supply for payloads, the long-term power consumption of the thermal control system varies with the total power of the satellites, which shall generally not be greater than 12% of the total power of the satellites, and the specific value may be determined with reference to the relevant requirements of QJ 3169;
b) for satellites with short-term power supply for payloads, the long-term power consumption of thermal control system varies with the average load power and payload duty ratio of satellites, which shall generally not be greater than 17% of the average load power of satellites, and the specific value may be determined with reference to the relevant requirements of QJ 3169;
c) the long-term power consumption value of thermal control system for spacecraft may be determined with reference to the relevant requirements of QJ 3169;
d) the long-term power consumption value of thermal control system for deep space probe may be determined with reference to the relevant requirements of QJ 3169;
e) the thermal control system is allowed to have appropriate short-term power consumption demand according to the specific requirements of spacecraft products.
