Evaluation Of The Thermal Environment Of Rabbit Huts Based On CFD Technology

With the increasing demand for rabbit products and the continuous development of the rabbit industry,the breeding methods have gradually changed from the initial small-scale family free-range to large-scale and intensive breeding.Despite the continuous improvement of farming technology,the development of the rabbit industry has been promoted.However,due to the physiological characteristics and disease characteristics of rabbits,factors such as environment,nutrition,disease,management and management are still affecting the production of rabbits.Among them,the indoor breeding environment(wind speed,temperature,relative humidity,etc.)is still one of the most important factors restricting the production level of rabbits.Therefore,it is necessary to monitor,evaluate and regulate the quality of the culture environment in the house to reduce the stress response of the rabbit,thereby improving autoimmunity,reducing the chance of disease,and making the performance potential of the rabbit excellent variety fully exerted,and finally achieving the improvement of production efficiency.In this study,the on-site thermal environment simulation evaluation of commercial rabbit houses under different ventilation modes in the southeastern coastal areas of China was carried out by on-site measurement and CFD simulation technology.The results can be used to optimize the environmental regulation of the rabbit house and the layout of the enclosure structure.This experiment is based on a commercial rabbit house in a rabbit farm in Datian County,Sanming City,Fujian Province.Based on CFD simulation technology,ICEM 18.0 software and Fluent 18.0 software are used to heat the rabbit house.The environment(wind speed,temperature and humidity,etc.)is simulated in a three-dimensional stable state.The simulation analysis results are as follows:(1)For rabbit houses with low-efficiency exhaust systems in cold winters,the simulation results show that: Under this ventilation mode,the airflow velocity in the shed is not evenly distributed.The wind speed is large at the inlet and outlet,and the wind speed in the middle area is low or even zero,and fails to reach the optimal wind speed of 0.1-0.2m/s in winter.The temperature at the height of three levels of Z=0.5,1.3,and 2.2m is increasing from the west wall of the small louver air inlet to the east wall of the air outlet,and the distribution range is 15.56°C-22.40°C,the temperature in the house is within the appropriate ambient temperature range of the rabbit.The relative humidity at the height of three levels of Z=0.5,1.3,and 2.2m shows a downward trend from the west wall of the small louver air inlet to the east wall of the air outlet,the distribution range is 54.39%-81.78%,just negatively correlated with the trend of temperature changes,the overall relative humidity in the house is slightly higher than the maximum ambient relative humidity within the requirements.(2)For the rabbit house adopting the water curtain ventilation cooling system in the hot summer,the simulation results show that: In this ventilation mode,the maximum wind speed on the three levels of Z=0.5,1.3,and 2.2m is mainly distributed near the inlet and outlet,at the same time,the uniformity of the wind speed in the rabbit rabbit cage on the Z=0.5m level is better,and the uniformity decreases with the increase of the height,the airflow wind speed in the house was slightly higher than the recommended wind speed of 0.4m/s in the summer in the rabbit house.The temperature of Z=0.5,1.3 and 2.2m presents an upward trend from the air inlet to the air outlet,the distribution range is 26.17°C-30.60°C,at the same time,the temperature in the middle and rear section of the Z=0.5m layer is higher and changes more than that in the same area of the Z=1.3m and 2.2m layers,however,the temperature in the shed did not exceed the critical adaptive ambient temperature of rabbits.The relative humidity at the height of Z=0.5,1.3 and 2.2m shows a downward trend from the air inlet to the air outlet,the distribution range was 71.61%-92.65%,it’s just negatively correlated with the temperature trend,at the same time,due to the short length of the rabbit house and the opening of the water curtain cooling system in summer,the overall relative humidity in the house is large,especially in the Z=1.3m and 2.2m layers with smooth air flow,the overall relative humidity in the house is higher than the maximum ambient relative humidity within the requirements.