RU2374149C1 - Method to control spacecraft thermal control system quality - Google Patents

Abstract

FIELD: space engineering.

SUBSTANCE: invention relates to space engineering, particularly to thermal control systems (TCS), primarily, of telecommunication satellites. Proposed method comprises periodic control over availability of required amount of heat carrier circulated in TCS fluid circuit exercised by determining actual volume of tight gas chamber of hydraulic accumulator filled partially with two-phase working fluid. Aforesaid chamber is separated by bellows with bottom from hydraulic accumulator fluid chamber communicated with TCS fluid circuit. It comprises also measuring temperature of heat carrier circulating in aforesaid circuit and, prior to determining actual volume of hydraulic accumulator gas chamber, the chamber temperature and heat carrier pressure are determined at pressure pickup locations. Proceeding from measurements made, actual volume of gas chamber is determined from the formula that allows for parametres taken in production of hydraulic accumulator. There parametres are represented by minimum and maximum possible volumes of gas chambers, as well as minimum tolerable pressure differences between gas and fluid chambers of hydraulic accumulator determined in measuring aforesaid minimum and maximum possible volumes of gas chamber (when bellows if completely expanded, or compressed). Aforesaid formula comprises as well TCS fluid path drag, working fluid saturated vapor elasticity (as specified in specs), measured heat carrier pressure at pickup location and hydrostatic component of pressure (in case tests are carried out on ground).

EFFECT: compact design, normal thermal control.

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Description

The invention, created by the authors in the order of performance of an assignment, relates to space technology, in particular to methods for controlling the quality of thermal control systems (CTP) of telecommunication satellites.

Known methods for controlling the quality of spacecraft (SC) spacecraft according to the patent of the Russian Federation No. 2209750 (application No. 2001111913 of 04/27/2001) [1] and spacecraft based on the patent No. 2151722 (application No. 99102571 of 02/08/1999) [2], based on which in the process of manufacturing, testing and operation of the STR (including hydraulic accumulators - volume compensators, having a liquid cavity with a coolant connected to the liquid path, where the coolant is circulated (single-phase or two-phase) in a closed loop using an electric pump unit (ENA), and gas w cavity partially filled with a two-phase working fluid (not more than 0.2 dm ³⁾ - two-phase working fluid, having at the chosen operating temperature liquid and vapor phase), such as the filling step of completely filled by the coolant liquid circuit (including a closed fluid path for circulating the liquid coolant cavity plus accumulator) are fused (have) the desired dosage according to the technical documentation (e.g., 2 dm ³⁾ of coolant liquid through the end gate circuit CTP compound o through ground shut-off valves with lines with a refueling and drain tanks, a vacuum pump and a source of compressed gas, and after draining the dose of coolant from the liquid circuit using a removable technological device mounted on a hydraulic accumulator containing reed switches, check (for example, to exclude possible operator error when draining the coolant dose), the resulting value of the volume of the gas cavity of the accumulator and is compared with the required fused dose - in the case of a qualitatively carried out discharge of the heat the carrier and, therefore, in the case of the presence of the required mass of the coolant in the STP fluid circuit, the required drained dose of the coolant must coincide with the volume of the gas cavity minus its structurally minimum possible volume of the gas cavity determined autonomously at the stage of manufacture of the hydraulic accumulator. As can be seen from the above, to ensure control of the gas cavity of the accumulator using the above technological device, the accumulator on the spacecraft must be installed so that it has free access and free space around it to install the above removable device, i.e. around the accumulator it is necessary to provide free volume due to the allocated working volume intended for the installation of spacecraft instruments.

In addition, to ensure periodic monitoring of the quality of the STR in conditions of orbital operation, according to the parameter: “The presence of the required mass of coolant in the liquid circuit of the STR” (meaning that the liquid circuit is tight), a standard device containing reed switches and a control unit for its operation must be provided as part of the STR , which will require an increase in the mass of the STR and, therefore, will require, for example, a decrease in the number of installed devices onboard the spacecraft.

Thus, a significant drawback of the known methods for controlling the quality of the STR is that when they are used, a reduction in the fill factor of the spacecraft of the allocated working volume by the spacecraft devices and to accommodate the entire envisaged mass of devices will require increased spacecraft dimensions with a corresponding increase in the mass of its structure.

An analysis of the sources of information on patent and scientific and technical literature showed that the closest in technical essence to the prototype of the proposed technical solution is a method for controlling the quality of STR KA according to [1].

The known method of quality control PAGE includes the following main sequentially performed operations (see figure 2):

- they make the components of the STR (including the accumulator 1.1.2: during the manufacturing process it measures the smallest possible volume of the gas cavity) and install (assemble) the STR on the structure of the spacecraft (1 - spacecraft; 1.1 - thermal control system; 1.1. 1 - a liquid path; 1.1.2 - a hydraulic accumulator (volume compensator) (1.1.2.1 - a liquid cavity with a coolant; 1.1.2.2 - a gas cavity with a two-phase working fluid; 1.1.2.3 - a bellows); 1.1.3 - an electric pump unit (ENA ); 1.1.4 - the panel on which it is installed KA devices are installed; 1.1.5 - radiator; 1.1.6 - filling valve; 1.1.7 - pressure sensor; 1.1.8 - temperature sensor);

- they check the degree of tightness of the liquid circuit for compliance with the required norm and carry out a complete filling of the previously evacuated liquid circuit with a deaerated coolant;

- install on the hydraulic accumulator 1.1.2 (the gas cavity 1.1.2.2 of the hydraulic accumulator is partially filled with a two-phase working fluid and separated from its liquid cavity 1.1.2.1 by a bellows 1.1.2.3; the liquid cavity is connected to the liquid path 1.1.1 of the circuit) a technological device with reed switches 2 and connect it to the remote control 3 control the operation of the device;

- measure the temperature of the filled coolant according to several temperature sensors 1.1.8 (for example, five sensors installed on the liquid path at different levels) and determine the average temperature of the coolant in the liquid circuit;

- the required dose of coolant is poured into the tanker’s capacity (the amount of the required drained dose depends on the amount of filled coolant, its average temperature, the operating temperature range and the required coolant supply under the conditions of operation of the CTP);

- using a device with reed switches 2, control the actual volume of the gas cavity 1.1.2.2 of the accumulator 1.1.2 after draining the coolant dose, which, when manufactured properly, must correspond to the required value determined (for example, when the coolant dose is drained so that one of the reed switch numbers is closed) according to the following ratio:

V _G.P. = V _G.P.min + V _J.K. Β · (t _max -t),

where V _G.P. - the required volume of the gas cavity, dm ³ ;

V _G.P.min - the minimum volume of the gas cavity, measured during the manufacture of the accumulator, dm ³ ;

V _J.K. - the maximum volume of the liquid circuit filled with the coolant, measured during its manufacture, dm ³ ;

β is the coefficient of temperature change in the volume of coolant, 1 / ° C;

t _max - the maximum temperature of the coolant at which the maximum volume of coolant in the liquid circuit, ° C;

t is the measured temperature of the coolant, ° C;

- check the normal functioning of the liquid circuit of the CTP, for which they switch on the operation of the electric pump unit (ENA) and monitor the compliance with the required norms of the measured values of flow, pressure and temperature in the liquid circuit and the parameters of the ENA.

If at all of the above stages of manufacturing and testing the controlled parameters of the CTP corresponded to the required standards, then it is considered that the CTP is made qualitatively and is allowed for further complex tests together with other systems in the spacecraft.

As mentioned above, a significant drawback of the known method of controlling the quality of the STR is that when it is used, it reduces the fill factor of the spacecraft allocated spacecraft due to restrictive requirements for the layout of the accumulator on board the spacecraft and increase its mass (the accumulator must be marked on the spacecraft as so that it has free access and there is sufficient free space around it for installing a removable technological device or a standard on-board device wa for measuring gas accumulator cavity volume).

The aim of the proposed technical solution is to eliminate the above significant drawback.

The goal is achieved by the fact that in the quality control method of the STR KA, which includes periodic monitoring of the presence of the required mass of the coolant charged into the liquid circuit by determining the actual volume of the sealed gas cavity of the accumulator, partially filled with a two-phase working fluid, separated by a bottom bellows from its liquid cavity, connected with the liquid path of the circuit, measuring the temperature of the coolant charged into the circuit and the smallest possible volume g the cavity of the accumulator during its manufacture and comparing the actual volume of the gas cavity with the required volume of the gas cavity of the accumulator, before determining the actual volume of the gas cavity of the accumulator, measure the temperature of the gas cavity and the pressure of the coolant in the liquid path of the circuit at the installation site of the pressure sensor and the actual volume of the gas cavity is determined according to

the following ratio:

where V _G.P.action is the actual volume of the gas cavity of the accumulator, dm ³ ;

V _G.P.min , V _{G.P. max} - the minimum and maximum possible volumes of the gas cavity, measured during the manufacture of the hydraulic accumulator, dm ³ ;

K is the coefficient characterizing the neutral position of the bellows when the pressure drop between the gas and liquid cavities is zero, according to the manufacture of the accumulator;

Δp _G.P.-ZH.P. V _{G.P. Max} , _{Δr G.P.-ZH.P.} V _G.P.min - the minimum possible differential pressure (between the vapor pressure of the working fluid and the coolant) between the gas and liquid cavities of the accumulator when measuring V _{G.P. max} (the bellows is fully extended) and V _G.P.min (the bellows is compressed completely), respectively, according to the manufacture of the accumulator, Pa;

P _St - the elasticity of the saturated steam of the working fluid according to the technical conditions for it at the above-measured temperature of the gas cavity of the accumulator, Pa;

R _DD - the measured pressure of the coolant in the liquid path at the location of the pressure sensor, Pa;

Δр _hydr - pressure difference - hydraulic resistance of the fluid path from the point of connection of the fluid cavity of the accumulator with the fluid path to the junction of the pressure sensor, Pa;

ΔН _DD - _bellows - the difference in altitude relative to the level of the Earth between the level of the coolant in the pressure sensor and the position of the bottom of the hydraulic accumulator bellows, m;

ρ _t is the density of the coolant, kg / m ³ ;

g = 9.80665 m / s ² is the normal acceleration of gravity during ground tests and g = 0 during operation in the conditions of orbital functioning, which, according to the authors, are essential features of the technical solution proposed by the authors.

As a result of the analysis carried out by the authors of the well-known patent and scientific and technical literature, the proposed combination of significant distinguishing features of the claimed technical solution was not found in the known sources of information and, therefore, the known technical solutions do not exhibit the same properties as in the claimed method of quality control of the STR KA.

The proposed method for controlling the quality of the STR KA includes the following sequence of operations (see figure 1):

- they make the components of the STR (including the accumulator 1.1.2 - in the manufacturing process it is measured:

V _G.P.min , V _{G.P. max} - the minimum and maximum possible volumes of the gas cavity (for example, ≈ 1 dm ³ and 5 dm ³ (excluding the volume of the working fluid equal to not more than 0.2 dm ³ ), dm ³ ;

K is the coefficient characterizing the neutral position of the bellows, when the pressure drop between the gas and liquid cavities is zero (for example, K = 2);

_{Δr G.P.-ZH.P.} V _{G.P. Max} , _{Δr G.P.-ZH.P.} V _G.P.min - the minimum possible differential pressure (between the vapor pressure of the working fluid and the coolant) between the gas and liquid cavities of the accumulator when measuring V _{G.P. max} (the bellows is fully extended) and V _G.P.min (the bellows is compressed fully) respectively (for example, according to the manufacturing data ≈ 10,000 Pa and ≈ minus 10,000 Pa) and carry out installation (assembly) of STRs on the structure of the spacecraft (1 - spacecraft; 1.1 - thermal control system; 1.1.1 - liquid path; 1.1.2 - accumulator (volume compensator) (1.1.2.1 - liquid cavity with a coolant; 1.1.2.2 - a gas cavity with a two-phase working fluid; 1.1.2.3 - a bellows; 1.1.2.3.1 - the bottom of the bellows); 1.1.3 - an electric pump unit (ENA); 1.1.4 - a panel on which are installed spacecraft devices; 1.1.5 - radiator; 1.1.6 - filling valve; 1.1.7 - pressure sensor; 1.1.8 - temperature sensors);

- check the degree of tightness of the liquid circuit (pos.1.1.1 + pos.1.1.2.1) for compliance with the required norm and carry out a complete refueling of the previously evacuated liquid circuit with a deaerated coolant;

- measure the temperature of the filled coolant according to several temperature sensors 1.1.8 (for example, five sensors installed on the liquid path at different levels) and determine the average temperature of the coolant in the liquid circuit;

- the required dose is poured (for example, V _{cd dose} = 2 dm ³ ) of the coolant into the tank of the refueling tank (the amount of the required drained dose depends on the amount of the filled coolant, its average temperature, the operating temperature range and the required coolant supply under the conditions of operation of the CTP);

- control the resulting actual volume of the gas cavity 1.1.2.2 of the volume compensator 1.1.2 after draining the coolant dose (should be equal to the sum of the volumes

(V _G.P.min = 1 dm ³ ) + (V _{next dose} = 2 dm ³ ) = 3 dm ³ ),

and then they are periodically monitored under conditions of ground tests and orbital functioning: before determining the actual volume of the gas cavity 1.1.2.2 of the accumulator 1.1.2, the temperature of the gas cavity 1.1.8 and the pressure of the coolant in the liquid path of the circuit at the location of the pressure sensor 1.1.7 are measured and the actual volume of the gas cavity 1.1.2.2 is determined according to the following relationship (the above ratio was established by the authors as a result of a comprehensive analysis of thermophysical processes, data in the STR and the hydraulic accumulator, and experimental data obtained by the authors so far in the process of experimental work):

where V _G.P.action is the actual volume of the gas cavity 1.1.2.2 of the hydraulic accumulator 1.1.2, dm ³ ;

V _G.P.min , V _{G.P. max} - the minimum and maximum possible volumes of the gas cavity, measured during the manufacture of the hydraulic accumulator, dm ³ ;

K is the coefficient characterizing the neutral position of the bellows 1.1.2.3, when the pressure drop between the gas and liquid cavities is zero, according to the manufacture of the hydraulic accumulator 1.1.2;

_{Δr G.P.-ZH.P.} V _{G.P. Max} , _{Δr G.P.-ZH.P.} V _G.P.min - the minimum possible differential pressure (between the vapor pressure of the working fluid and the coolant) between the gas and liquid cavities of the accumulator 1.1.2 when measuring

V _{G.P. max} (bellows 1.1.2.3 fully extended) and V _{G.P. min} (bellows 1.1.2.3 fully compressed), respectively, according to the data on the manufacture of the hydraulic accumulator 1.1.2, Pa;

P _St is the elasticity of the saturated steam of the working fluid according to the technical specifications for it at the temperature of the gas cavity 1.1.2.2 of the accumulator 1.1.2, Pa measured above (analysis of the experimental data showed that the period of time when draining the coolant dose between the operations of draining the dose and measuring the pressure of the coolant in the liquid path is equal to at least 5 min and during this time the pressure in the gas cavity (with a volume of ≈ 3 dm ³ ) of the accumulator is close (up to ≈ 95%) to the value of the vapor pressure of the working fluid (quantity in the working fluid, for example, Freon 141c, in the gas cavity is equal to not more than 0.2 dm ³ ), and under the conditions of the spacecraft operation, the temperature of the coolant in the liquid circuit and the gas cavity of the accumulator change quite slowly for 5 minutes and at the same time the pressure in the gas cavity close to the value of the elasticity of the saturated vapor of the working fluid within the limits of measurement error):

R _DD - the measured pressure of the coolant in the liquid path at the installation site of the pressure sensor 1.1.7, Pa;

Δр _hydr - pressure difference - hydraulic resistance of the fluid path from the point of connection of the fluid cavity 1.1.2.1 of the accumulator with the fluid path 1.1.1 to the point of connection of the pressure sensor 1.1.7 (according to the data of the CTP development and experimental data), Pa;

ΔН _ДД - _bellows - height difference relative to the ground level between the coolant level in the pressure sensor 1.1.7 and the bottom position 1.1.2.3.1 of the hydraulic accumulator bellows 1.1.2.3 (according to the data of the drawings on the spacecraft), m;

ρ _t is the density of the coolant, kg / m ³ ;

g = 9.80665 m / s ² - normal acceleration of gravity during ground tests and g = 0 during operation in conditions of orbital functioning;

- determine the required volume of the gas cavity 1.1.2.2 in the following ratio:

V _G.P. = V _G.P.min + V _J.K. Β · (t _max -t),

where V _G.P. - the required volume of the gas cavity, dm ³ ;

V _G.P.min - the minimum volume of the gas cavity, measured during the manufacture of the accumulator, dm ³ ;

V _J.K. - the maximum volume of the liquid circuit filled with the coolant, measured during its manufacture, dm;

β is the coefficient of temperature change in the volume of coolant, 1 / ° C;

t _max - the maximum temperature of the coolant at which the maximum volume of coolant in the liquid circuit, ° C;

t is the measured temperature of the coolant, ° C;

- compare the above-defined values of V _{G.P. Deist} and V _G.P. among themselves: if they differ from each other by no more than a measurement error, then this confirms the presence of the required mass of coolant in the liquid circuit (meaning that the liquid circuit is sealed);

- check the normal functioning of the liquid circuit of the CTP, for which they include (if not included) the electric pump unit 1.1.3 (ENA) and monitor compliance with the required norms of the measured values of flow, pressure and temperature in the liquid circuit and the parameters of the ENA (compliance of the above values with the required standards are realized only if the required mass of the coolant in the liquid circuit is available).

If at all of the above stages of test production and operation the controlled parameters of CTP 1.1 comply with the required standards, this indicates that the CTP 1.1 is manufactured with high quality, in particular, the tightness of its liquid circuit corresponds to the required norm, and is allowed for further testing and operation as part of the spacecraft one.

As can be seen from the foregoing, according to the technical solution proposed by the authors in the manufacture, testing and operation of PAGE 1.1 KA 1 without deterioration of the quality control results, its hydraulic accumulator 1.1.2 can be installed in the KA 1 zone most functionally suitable for it - near the X-axis and in the most remote from the spacecraft’s center of mass 1 zone and there is no need to fulfill the requirements for ensuring free access to the hydraulic accumulator 1.1.2 and the presence of additional free volume around the hydraulic accumulator 1.1.2 (since excl. A device with reed switches from the STR (on board the spacecraft) has been developed), which provides an increase in the fill factor of the allocated working volume by spacecraft devices and, therefore, eliminates a significant drawback of the known technical solutions, i.e. thereby achieving the objective of the invention.

Claims (1)

A method of quality control of a spacecraft thermal control system, including periodic monitoring of the required mass of the coolant charged into the liquid circuit by determining the actual volume of the sealed gas cavity of the accumulator, partially filled with a two-phase working fluid, separated by a bellows with a bottom from its liquid cavity, connected to the liquid path of the circuit, measuring temperature of the coolant charged into the circuit and the smallest possible volume of the gas cavity accumulator during its manufacture and comparison of the said actual volume of the gas cavity with the required volume of the gas cavity of the accumulator, characterized in that before determining the actual volume of the gas cavity of the accumulator, the temperature of this cavity and the pressure of the coolant in the liquid path of the circuit at the location of the pressure sensor are measured, and the actual volume gas cavity
accumulator (V _G.P.action , dm ³ ) is determined according to the following ratio:

where V _G.P.min , V _{G.P. max} - the minimum and maximum possible volumes of the indicated gas cavity, measured during the manufacture of the hydraulic accumulator, dm ³ ;
K is the coefficient characterizing the neutral position of the bellows, when the pressure drop between the gas and liquid cavities is zero, taken according to the manufacture of the accumulator;
Δr _{G.P.-Zh.P.V G.P.maks} , _{Δr G.P.-Zh.P.V G.P.min} - the minimum possible differential pressure (between the vapor pressure of the working fluid and the coolant) between the gas and the liquid cavities of the accumulator when measuring V _{G.P. max} (bellows fully stretched) and V _{G. P. min} (bellows fully compressed), respectively, according to the manufacture of the accumulator, Pa;
P _St - the elasticity of the saturated steam of the working fluid according to the technical conditions for it at the measured temperature of the gas cavity of the accumulator, Pa;
R _DD - the measured pressure of the coolant in the liquid path at the location of the pressure sensor, Pa;
Δр _hydr is the pressure difference characterizing the hydraulic resistance of the fluid path, from the point of connection of the fluid cavity of the accumulator with this path to the place of installation of the pressure sensor, Pa;
ΔН _{DD - bellows} - the difference in altitude relative to the level of the Earth between the level of the coolant in the pressure sensor and the position of the bottom of the hydraulic accumulator bellows, m;
ρ _t is the density of the coolant, kg / m ³ ;
g = 9.80665 m / s ² - normal acceleration of gravity during ground tests and
g = 0 during operation in the conditions of orbital functioning.

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