Thermal Modes Simulation of Household Absorption-Type Refrigerating Unit Rectifier Lift Site

Currently, developers of modern refrigeration equipment, in accordance with the plans of the UN, are moving to natural refrigerants (hydrocarbons, carbon dioxide and ammonia) that do not have an adverse technological impact on the ecosystem of the planet. In domestic refrigeration technology, one of the options is absorption refrigerator, the working body of which is water-ammonia mixture with addition of hydrogen. Having a number of unique advantages over compression analogs, absorption systems are characterized by lower energy characteristics. Since the absorption apparatus is designed initially to "hard" operating conditions, then with a decrease in the ambient temperature, and, consequently, heat flows into the chamber, all the basic elements of the ARU, with the exception of the reflux condenser, are able to operate under more favorable conditions. A reflux condenser, which is also designed to operate under "hard" conditions, in this case, in addition to its direct function of cleaning ammonia vapors from water vapor, also detains part of the ammonia entering the condenser. At the same time, it is obvious that the lower the ambient temperature, the greater this part will be. Ultimately, a decrease in the ambient temperature results in a decrease in the cooling capacity with a constant thermal load on the thermosyphon, COP of the refrigeration unit. As the analysis showed, the maximum thermodynamic losses in absorption refrigeration aggregates are concentrated in the generator unit during evaporation of ammonia, its purification from water vapor and transport to the evaporator. In this connection, the mathematical modeling of the thermal modes of the reflux condenser was performed, which is responsible for the purification and transportation of ammonia vapor. Modeling was carried out on standard designs of absorption cooling units taking into account reasonable assumptions and results of own experimental researches. At the heart of model representations lie the laws of conservation of heat and mass. Due to the high thermal inertia of the processes in the rectifier, stationary operating modes were modeled. In the simulation, the flow mode of the vapor mixture in the rectifier was considered turbulent, and the radial diffusion processes were neglected. As a result, the method for calculating the thermal modes of a reflux condenser, which is applicable for typical design of household absorption refrigeration unit has been developed.