Modeling of Thermal Modes of the Reflux Condenser of the Absorption Refrigeration Unit

Abstract

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 refrigeration units, the working body of which is an aqueous ammonia mixture with the hydrogen addition. Having a number of unique advantages over compression analogs, absorption systems are characterized by lower energy characteristics.As the analysis shows, the maximum thermodynamic losses in the absorption aggregates are concentrated in the generating unit when the ammonia is evaporated, it is purified from water vapor and transported to the evaporator. In this connection, the mathematical modeling of the thermal regimes of the reflux condenser is performed, which is responsible for purification and transportation of ammonia vapor.Modeling is carried out on standard designs of absorption refrigeration units taking into account reasonable assumptions and results of own experimental researches. A cellular model is used. Stationary operating modes are modeled due to the high thermal inertia of the processes in the reflux condenser.As a result, the perspective of the thermal insulation installation throughout the reflux section is shown, which makes it possible to increase the energy efficiency by 17...22 %.

Підвищення Енергетичної Ефективності Комбінованих Абсорбційних Холодильних Приладів

“…[35,36] та Холодкова А.О. [37], які були присвячені вирішенню проблеми мінімізації енергоспоживання традиційного АХП за рахунок удосконалення режимів транспортування аміаку через дефлегматор АХА.…”

Improving the energy efficiency of solar systems for obtaining water from atmospheric air

“…As the analysis of studies [23][24][25] shows, this is largely due to low efficiency of transportation of a refrigerating agent -ammoniathrough an AWRU refluxer at operation in a wide range of outside air temperatures. There are unclear losses of ammonia at low outside temperatures, and a significant amount of water enters an AWRU evaporator at elevated temperatures, which leads to a decrease in efficiency of the cooling process.…”

“…Saturated WAM with a mass consumption -, ent G′′ temperature -, ent ϑ and a mass concentration -. ent ξ′′ enters the inlet (to the bottom part) of a partially insulated refluxer [25].…”

“…In the operating mode of such AWRU [25], linear velocity of a WAM flow lies in the range of 0.0075-0.0130 m/s. This speed range corresponds to a laminar flow mode with Reynolds numbers of 350-600.…”

“…The presence of a laminar stream of a WAM flow does not imply perfect mixing of a flow in the radial direction [25,39,40]. In this case, there is a kind of resistance to a transverse flow of matter, and it seems expedient to take into account such a factor to create the most adequate model of a refluxer.…”