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Development of low-temperature and cryogenic thermal control systems used in spacecrafts is one of the difficult and interesting scientific task. Lavochkin Association has been designing such systems since 1968. Since 1972 the low-temperature thermal control systems with application of diode heat pipes, radiators with heat pipes, thermal storages with PCM have been successfully operating on board of spacecrafts “OKO” and “OKO-1”. The present paper describes the recent developments of the low-temperature arterial Heat Pipes and technical solutions applied in cryogenic system of the “OKO-1” family. Latest satellite put in orbit in April 2003.

In 1995 TAIS Ltd developed and manufactured a Thermal Control System (TCS) for Nickel-Cadmium Batteries (NCB) based on Loop Heat Pipes (LHP). This TCS was ordered for the Chinese meteorological satellite FY-1C by Shanghai Institute of Spacecraft Engineering. The paper presents results of comparative analysis for some design features of the TCS, thermal vacuum test results, description of TCS layout for the NCB on board the FY-1 C satellite, test results for TSC after its integration into the satellite and flight telemetry data.

Method of the Loop Heat Pipe's (LHP's) heat transfer characteristics' determination by using nomograms is described in present paper. Graphs, presenting the characteristics of the different parts of the LHP, that have been drawn in combined coordinate system, permit to determine the “working points” which meet the main requirements on the LHP operation.

Thermal Control System based on different types of Heat Pipes (HP), including Loop Heat Pipes (LHP) has been designed, manufactured and tested. The goal to design and to launch the Thermal Control System with LHP was established and achieved.

Loop heat pipes (LHP) combine the classical heat pipe operation principle with a loop configuration, i.e. evaporator and condenser are located at separate places as dictated by thermal and configurational reasons and are connected lines for fluid and vapor transport. Experimental investigations of such LHP revealed certain temperature oscillations under certain conditions. This paper presents the results of analyses of such temperature fluctuations and offers possible explanations for initiation and termination of such behavior. Two types of temperature fluctuations have also been confirmed experimentally by testing different kinds of LHP.

A universal autonomous controlled heat transferring module on base of two-phase loop with capillary pump have been elaborated. This module consists of one evapourator and one radiator-condenser. Various variants for suggested module control by using of active or passive elements, providing the CPL start-up, restarting and temperature regulation, have been considered. There is determined a structure concept and recommendations on mathematical modeling of Thermal Control System (TCS), made on base of several controlled heat transferring modules with capillary pumps, are given. There are given results of computer experiment with mathematical model of artificial Earth satellite payload TCS. This TCS consists of four controlled, independent in power supply, CPL, which start-up and control are carried out by using of passive devices.

A capillary pumped two-phase ammonia heat transport loop, developed at Lavochkin Assoc., Moscow, was tested under laboratory conditions at ERNO, Bremen. The tubular capillary pump evaporator contains a sintered Nickel powder body with a small pore size of 1. 5 μm. The line diameter of the vapour and the liquid line is only 6 mm and 4 mm, respectively, allowing an easy accomodation to any architecture in the filled state. The objective of the test was to determine the heat transport performance of the loop under different orientations w.r.t. gravity under steady state and transient, in particular priming load conditions. The tests have demonstrated a large heat transport performance of more than 1100 W in a vertical orientation, where the evaporator was located 2 m (!) above the condenser. The priming ability appears to depend on the load timeline as well as on the orientation.