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One of relatively modern directions of two-phase technology in Russia is the development of thermoautofluctuating two-phase heat transferring devices (TTHD ). It is very complicated to classify these devices because of great amount of its constructive variations. However, it is possible to notice, that all TTHD differ from other two-phase heat transferring devices (such, as heat pipes, thermo-syphons, CPL and etc.) by following: circulation of working fluid in TTHD happens periodically. In separate elements of TTHD the liquid, at first, is serially accumulated and then it is spended, and this process is periodically repeated. In some cases the element, in which there are excited the thermoautofluctuations, can functionally execute the role of usual pump providing circulation of liquid working fluid. At the same time thermoautofluctuations are supported by means of usual small-power heater (for example, electrical).

In this paper there are considered some differences between the Loop Heat Pipes (LHPs) and the Capillary Pumped Loops (CPLs) performances. There offered the methods of the capillary evaporators reliability function increasing for two-phase systems of the LHP and the CPL type. The reliability increasing of above mentioned systems evaporators is proposed to be done by using of composite wicks and/or thermal electrical coolers. The recommended means could decrease the probability or except completely the “vapor blocade” of absorbing surface of evaporators capillary pumps.

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.

The mathematical model of capillary pump loop (CPL) with the capillary pump for a conditions of radiative heat removal in the condenser has been considered. The CPL calculation results of both functional characteristics are being analised with the presence of in flow heat from the outside sources and the influence of non-condensing gases and mass forces on the starting and dynamic characteristics of the installation. The heat transfer system is shown to possess controlling properties.