On efficiency improving of thermal control system of low-thrust engines block of the Fregat inter-orbital space tug

Аuthors

Bugrova A. D., Kotlyarov E. Y.^*, Luzhenkov V. V., Finchenko V. S.

Lavochkin Research and Production Association, NPO Lavochkin, 24, Leningradskay str., Khimki, Moscow region, 141400, Russia

*e-mail: evgeny-1@list.ru

Abstract

The article regards a prospective version of local thermal control system (TCS) of a of lowthrust

engines block (LTE) of the Fregat inter-orbit space tug (FIOST). The authors propose to

increase the cooling capacity of the TCS by introducing an evaporative heat exchanger (EHX)

into its configuration. This will allow enhancing the FIOST functionality. The Fregat interorbital

space tug is a typical product of Lavochkin Association, which contributed to more than

76 successful launches, and putting into working orbits of at least 200 domestic and foreign

spacecraft. In the process of some spacecraft launch employing the FIOST, it was revealed that

the LTE operation in the most intense conditions was accompanied by an increase in the temperature

of individual engine elements above permissible limit. In this regard, technological

measures were taken, aimed at improving the cooling efficiency of LTE blocks. The article presents

a TCS schematic diagram, and shows as well that the simplest way to the cooling capacity

increase consists in employing the open surfaces of the box on which a block of three engines is

assembled as radiators. It was shown additionally that this kind of solution had an energetic limit,

which could be overcome by installing an evaporative heat exchanger on the same box.

Further, the authors present the developed thermal mathematical model, which allows predict

parameters of the TCS containing an evaporative heat exchanger (EHX), as well as evaluate effectiveness

and feasibility of its application. To set up a computational experiment, the authors

use the ThermXL demo version. The results are presented for two cases, namely, the uniform

and pulsed nature of the LTE operation. The results are commented and illustrated by additional

quantitative evaluations. It is shown, that the EHX is most effective for compensating the LTE

short-term powerful turn-on. In conclusion, the possible impact of evaporative heat exchangers

on the Fregat operation and the payload is analyzed. By simplified estimation, it was concluded

that EHX functioning had no significant impact. It is noted, that the EHX developing is possible

through design and experimental work, which will include autonomous tests. The obtained results

might be of certain interest for specialists involved in ensuring thermal regime of the

spacecraft equipment.

Keywords:

evaporative heat exchanger, Fregat versatile space tug, low thrust engines, computational experiment, thermal mathematical model.

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