Increase of Energy Efficiency of Household Absorption Refrigerating Devices

Absorption refrigerators (AR) with absorption cooling units (ACU) have an increased energy consumption during operation due to the thermodynamic imperfection of the absorption refrigeration cycle, the presence of low-intensity diffusion processes of mass transfer in the evaporator and absorber and the losses associated with evaporation and Subsequent transportation of ammonia from the generator unit to the condenser and then the evaporator. The greatest effect in energy saving during the operation of ACU with minimal changes in design can be achieved by improving the operation modes of generating units. The main direction of modern research of AR is aimed at qualitative obtaining of experimental data. The objects of experimental research were modernized models of household absorption single-chamber refrigerators "Kyiv- 410" and "Kristall-408". The modernization consisted in the installation of an additional heat-insulating casing on the generating set in such a way that the entire lifting section of the reflux condenser was closed. The parameters of the heatinsulating casing were chosen taking into account the known recommendations, in particular, the thickness of the thermal insulation made of glass fiber was 4 mm. To estimate the rate of displacement of the inert gas during the starting period, the amount of generated steam was calculated by calculation. For the analysis, the results of known studies and own experience were used. It was shown the expediency of forcing the heat load on the generator - the reduction of energy costs during the start-up period can be from 25 to 35%. Taking into account the calculation results, the original three-position control methods of AXA with the thermal load input to the generator "110 - 70 - 0" and "130 - 70 - 0" were proposed. It is shown that the method of controlling the AR with a constant two-stage supply of heat load and controlling the flow temperature at the outlet of the reflux condenser allows to reduce energy consumption by up to 20 %, in comparison with traditional position control. Despite the constant in time supply of heat load to the generator, the advantage was achieved due to: A) maintaining the elements of the generating set in the "warmed up" state, which makes it possible to minimize the transition time to the mode with the rated refrigerating capacity of the evaporator; B) maintaining the minimum refrigerating capacity of the evaporator in the "waiting" mode. The energy-saving effect of the new control method is largely related to the installation of the heat-insulating casing on the dephlegmator. This allows not only to use the minimum refrigerating capacity of the evaporator (at Q = 40 W), but also to switch to a lower level of rated thermal load (Q = 70 W) compared to the serial version (Q = 110 W). The duration of the working period for absorption refrigerators is related to the inertia of the startup processes, when all the energy input is spent only on the heating of the elements of the generator assembly. In this regard, measures aimed at maintaining energy-efficient operation modes of the generating set, despite the additional energy costs, provide advantages in energy saving...