Моделювання теплових режимів абсорбційного термотрансформатора з тепловими трубами

Abstract

Method for modeling thermal modes of an absorption thermal transformer with heat pipes is proposed, the suggested method allows to improve its temperature and energy characteristics due to rational design layout. Mathematical model of the thermal circuit "evaporator of the absorption thermal transformer – heat pipe – cooling object" has been developed, which allows conducting a numerical experiment to assess the effect of the following geometric and mode parameters on the temperature and energy characteristics of the absorption thermal transformer, namely the box of the cooling object: depth, width and width; thickness of the box material of the cooling object; type of box material; type of the heat pipe used taking into account the value of thermal resistance; thickness of heat-insulating partitions. The method for calculating thermal modes is based on the heat balance equation, which takes into account the cooling capacity of the evaporator of the absorption thermal transformer, the influx of heat the environment through the walls of the cabinet, doors and partitions, as well as the influx of heat the products. The variable parameters were: box thickness — 0.003 m and 0.001 m; box height — 0.160 m, 0.200 m, 0.280 m; box depth — 0.225 m, 0.325 m, 0.425 m; thermal resistance of heat pipes — 0.01 K/W, 0.1 K/W, 1 K/W. The basic designs for the analysis are boxes with L-shaped, U-shaped and traditional heat pipes. As a result of the numerical experiment, it was proven that for the size of the cooling object: height — 0.160 m, width — 0.385 m, depth — 0.225 m, the installation of a heat pipe equalizes the temperature to 0.2 °C. The mode is reached faster by about 20 %. Increasing the depth of the box 0.225 m to 0.425 m reduces the efficiency of using heat pipes by 45 %, and increasing the height 0.160 m to 0.280 m reduces the efficiency of using heat pipes by 2.6 %. For developers of absorption thermal transformers with a useful volume of the cooling object of 12...30 dm3 and 100...180 dm3, it is possible to recommend a box design with dimensions of 0.160×0.225×0.385 mm, and with L-shaped or U-shaped heat pipes. The heat carrier of the heat pipes is ammonia.