Research Of Low Profile Cross Ventilated Barn On Regional Adaptability

With the rapid development of the national economy,the demand for dairy products is increasing,and the traditional methods of dairy farming have been unable to meet the existing requirements.The Low Profile Cross Ventilated(LPCV)barn was introduced in China as a new kind of building type,with the advantages of annual controllable environment,low construction costs,and large-scale farming attracted the attention of many large domestic pastures.China is a large country with great difference in climate between different regions,which makes the application effect of the LPCV barn varies a lot from region to region.In order to avoid blindly copying and following the construction of barn building in this type,four typical climate areas were selected combined with China climate zoning and pastoral distribution,method of computational fluid dynamics(CFD)simulation was carried out to study the geographical adaptability of LPCV barn.The improvement programs of the barn were proposed and economic analyses of the programs were carried out.The research results could be used as the reference for optimal design of LPCV barn as well as the pre-existing LPCV barn design reference in China,which could also provide reference for the operation regulation of wet curtain fan system.The model of LPCV barn was established and temperature distribution between the windshield of the barn was simulated based on the CFD method,the correctness of the model was verified by comparing the simulation results with the results of Harner's measurements.The air flow distribution of LPCV barn under different air exchange rates was numerically simulated,and the optimal air exchange rate of the barn was obtained by analyzing the simulation results.Indoor thermal environment of LPCV barn in four areas was simulated,it could be found that wet pad cooling system showed high efficiency of cooling in high temperature and low humidity areas,the limitation in high temperature and high humidity areas.The high temperature and high humidity areas LPCV barn liquid desiccant scheme was proposed referring to greenhouse dehumidification program,the economic analysis of the scheme was carried out and its feasibility was proved.Based on the method of numerical simulation,the optimal air exchange rate of the barn in winter was obtained,and the ventilation effect was best when the air exchange rate was 180 s.Temperature distribution of LPCV barn in four areas when ventilation was not heated in winter was simulated.It was found that temperature in barn could not meet the requirements of comfort temperature of the dairy cows.The temperature-rise program was proposed and economic analysis was carried out,and its feasibility of the scheme was proved.