Modeling of the manual non-stopped current modes of the liquid phase of the working body in the elements of absorption refrigerating devices

In the transition of household refrigeration to natural working bodies occupy a special place refrigerators with absorption refrigeration units (ARU). ARU working medium is a water ammonia solution with an inert gas (hydrogen, helium or their mixture). The operation of absorption refrigerators can be carried out from any source of thermal energy with sufficient temperature potential. ARU have no moving elements in the design, are silent and reliable in operation, their cost is minimal among analogues. The main drawback of absorption refrigerators is high energy consumption. This is due to the lack of model ideas about the processes of heat and mass transfer and flow regimes of the working fluid in the elements of the ARU in the development and design of serial models. Only a model for calculating the ARU evaporator is known, which includes empirical relationships borrowed from the work of the Leningrad Institute of Food and Refrigeration Industry and allow determining the average flow rate of the liquid phase and the configuration of the stream section. These relationships, however, are applicable only to pipes with a smooth inner surface, they do not take into account the influence of surface tension forces that bend the interfacial surface; besides, for these the range of parameters in which they are obtained is not given. Therefore, they should be considered as indicative and applicable only for preliminary assessments. The special literature discusses methods for calculating rippled turbulent sections characteristic of river effluents and large canals, which is not applicable for evaporator tubes and ARU absorber with diameters of the order of 20 mm. Studies by employees of the Odessa National Academy of Food Technologies and the Vasilkovsky Refrigerator Plant showed that a laminar flow of the evaporating ammonia-coolant liquid phase takes place in the cylindrical tube of the ARU evaporator. The liquid forms a trickle moving under the action of gravity along and down the pipe located at an angle to the horizon. The forces acting on the element of a liquid coolant moving uniformly inside a smooth pipe are considered. The flow model without the surface tension of the liquid is presented. There were two ways to solve the problem. In the first method, it was assumed that the fluid flow is layered and its layers are concentric with the inner surface of the pipe. The expression obtained as a result of the simulation is the dependence of the flow rate of the fluid on the half-angle of the cross section.