Some recommendations about the use of the generalized heat transfer characteristic of heat pipes when modeling them as part of a spacecraft

Аuthors

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

Lavochkin Research and Production Association, NPO Lavochkin, , Khimki, Moscow region, Russia

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

Abstract

The article describes a methodological approach that allows determining and justifying the value of the effective heat transfer coefficient (EHTC) in the capillary structure zone of heat pipes (HP) for subsequent modeling of a specific type of HP in thermal mathematical models of thermal control systems (TCS) of spacecraft (SC). A more correct representation of the conductivity of the HP allows for an adequate reproduction of their functioning as part of the system and, as a consequence, a more correct prediction of the temperature state of the onboard equipment of the spacecraft. The authors proposed to determine the effective heat transfer coefficient of the heat pipe in the process of solving the inverse problem of heat conductivity using the results of thermal vacuum tests performed on a batch of axial heat pipes. Some recommendations are presented, on the basis of which it is proposed to implement modeling of the ATT in thermal mathematical models of the spacecraft’s TCS. The results of computational and laboratory experiments are considered, within the framework of which a partial justification of the value of the effective heat transfer coefficient reproducing two-phase heat exchange in the axial HP during their operation as part of the spacecraft is carried out. Using modern software packages (and in some cases, our own software codes), it is possible to organize a complex experiment that combines natural and computational experiments, which, in turn, will complement each other, achieving a positive effect in improving the thermal mathematical models (ТММ). A refined mathematical model which is capable to reproduce a natural experiment makes it possible to either expand the conditions for using the object under study: using a virtual environment whose capabilities exceed those of a laboratory stand, or to “penetrate” those parts/zones of the object under test that are difficult to access for installing sensors, as well as in cases where installing sensors on the object can distort the physical essence of the experiment. Using the methodological approach presented here and similar ones, it is recommended to supplement and expand the base of empirical effective coefficients characterizing the operation of heat transfer units. The use of heat transfer characteristics that best reflect real ones will significantly improve the quality of engineering design. The results of the work performed here may be interesting and useful for developers of heat transfer systems based on heat pipes. 

Keywords:

thermal mode, thermal mathematical model, calculation experiment, axial heat pipe, evaporator, condenser

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