Numerical Simulation And Optimization Of The Air Distribution Of Air-cooled Chillers And Air Supply Pipes

In recent years, with the emergence of a large number of high-rise buildings, senior buildings and large urban complexes, the arrangement of the air-conditioning system also has become complicated. The cold and heat source of air-conditioning and the air condition pipe system are important parts of the central air-conditioning system, their reasonable layout and design have important significance to the air conditioning effectiveness, indoor air quality and energy saving. However, the experience method is adopted generally in designing cold and heat source of air-conditioning and air conditioning pipe system, this causes the cold and heat source of air-conditioning and air conditioning pipe system can’t meet the design requirements.Firstly, the air distribution of equipment layer which placed air-cooled chillers under the natural exhaust method was numerically simulated by using CFD technology, the results showed that the air distribution within the equipment layer was in disorder. The outdoor airflow couldn’t successfully enter into the equipment layer and high-temperature exhaust discharged from air-cooled chillers appeared back-mixing phenomenon. This seriously affects the heat exchange performance of air-cooled chillers.Secondly, aiming at the deficiencies of the equipment layer’s air distribution scheme, the organized exhaust method was proposed to improve the air distribution within the equipment layer. The CFD computational models with the optimization scheme of the equipment layer was established. The air distribution of the optimization scheme was obtained, and made a comparison with the original design scheme’s. The results showed that the airflow distribution within the equipment layer under the optimization scheme was better. High-temperature exhaust discharged from air-cooled chillers was successfully exhausted to outside under the organization of air-exhausting pipes and bellows, which effectively prevented the back-mixing of high-temperature exhaust. Outdoor airflow also could successfully enter into the equipment layer. This ensures that the air-cooled chillers can be highly efficient and stable operation.Finally, taking the air supply system of the all-air air conditioning system as the research object, the velocity, pressure and outlet flow cases of air supply ducts and air terminal devices were numerically simulated. The results showed that the design scheme of the all-air air conditioning system’s air supply system was relatively reasonable. The velocity and pressure distribution in the air supply branch pipes was relatively uniform. The air supply outlets of air terminal devices relatively uniformly supplied air, which the supply air volumes were without big difference. But through the comparison between the outlet flow rates of air terminal devices and the supply air volumes which met design requirement in corresponding areas, it was found that the supply air volumes in each area of two air conditioning units on the east and west sides couldn’t meet the design requirements in the case of the air valves of air terminal devices fully opened. Therefore, in actual operations, a smaller valve opening was recommended to use in air terminal devices of the areas where the supply air volumes were too large.The results of this study have important guiding significance for optimization of air-conditioning system and also have the reference significance for other similar design of the air-conditioning system of large buildings.