CFD Numerical Simulation Of The Air Of Low Profile Cross Ventilated Barn In Shenyang

With the development of dairy farming, the traditional breeding methods like free-ranging and rear livestock in pens has already cannot satisfy the requirements of modern animal husbandry. In 2005, the first Low profile cross ventilated(LPCV) barn was built in America. The LPCV barn can satisfy the need for breeding a large scale of dairy cattle, but there are still some problems of it. Firstly, the air flow field is nonuniform in the barn, thus the air flow field is vivid in different part of the barn. Secondly, the experience point of air exchange time for the barn is 60s~80s in the summer, which is not an accurate value. Thirdly, if the barn were ventilated with cold wind during the winter in the cold area, it will drop the temperature of the barn vastly, which will result in some health problems about dairy cattle such as congelation.The topic use FLUENT software to simulate and analyze different kinds of barn models. Each of the barn models has a different angle of wind deflector, 30°, 60°and 90°, respectively. Next we will simulate the velocity profile of the three models by FLUENT software. Then the optimal angle of wind deflector will be found out through the analysis of simulation results. Secondly, the FLUENT software should stimulate four kinds of flow filed within the barn. The air exchange time of flow filed is 60 s, 80 s, 100 s and 120 s, respectively. Then the best air exchange time will be found by comparing the barn to air temperature, air velocity and CH4 concentration. At last, the barn will be simulated in three different kinds of situations respectively, with the skylight opened or closed and supplying wind with different temperature. Then the best ventilation way in winter will be selected by comparing the simulation results.Based on the simulation results by the FLUENT software, the best angle of wind deflector for barn is 30°; the best air exchange time of the LPCV barn is 80 s during the summer; and it will consume less energy in winter with the skylight opened which can also make the temperature more homogeneous in the barn. Besides, in order to maintain the temperature above zero, the temperature of the supply air should be hold up to 4℃. The research of this topic could supply reference for the construction of LPCV in the cold region, could also supply some methods for further research of LPCV.