Simulation of Thermal Modes of the Absorption Thermotransformer With Heat Pipes

Methodology for thermal regimes simulation of absorption thermotransformer with heat pipes is proposed, which, through rational structural construction design, improves its thermal and power performance.Mathematical model has been developed for the thermal system comprising the “absorption thermotransformer evaporator – heat pipe – cooling object”, which enables numerical experiments to evaluate the influence of the following geometric and operating parameters, namely: depth, width, and height of the cooling facility enclosure; thickness of the cooling facility enclosure material; type of enclosure material; type of heat pipe used, taking into consideration its thermal resistance; and thickness of the thermal insulation barriers on the thermal and power characteristics of the absorption thermotransformer, specifically, the cooling facility enclosure. The basis of the thermal modes calculation methodology is the thermal balance equation, which accounts for the absorption thermotransformer evaporator cooling capacity, heat transfer from the surrounding environment through the cabinet walls, doors, and barriers, as well as heat input from the stored products.The varied parameters included: enclosure thickness – 0.003 m and 0.001 m; enclosure height – 0.160 m, 0.200 m, 0.280 m; enclosure depth – 0.225 m, 0.325 m, 0.425 m; and thermal resistance of the heat pipes – 0.01 K/W, 0.1 K/W, 1 K/W.The baseline designs for analysis were enclosures with L-shaped, U-shaped, and conventional heat pipes.As a result of the numerical experiment, it was proven that for a cooling object size of height – 0.160 m, width – 0.385 m, and depth – 0.225 m, the installation of a heat pipe equalizes temperatures to within 0.2 °C. The operating mode is reached approximately 20% faster. Increasing the depth of the enclosure from 0.225 m to 0.425 m reduces the efficiency of heat pipe usage by 45%, while increasing the height from 0.160 m to 0.280 m reduces efficiency by 2.6%.For developers of absorption thermotransformers with cooling object net capacity 12...30 dm³ and 100...180 dm³, the recommended enclosure design is with dimensions of 0.160×0.225×0.385 m, and with L-shaped or U-shaped heat pipes. The working fluid of the heat pipes is ammonia.