Spatial distributions of air humidity in a cows barn under different rates of forced ventilation

Abstract

Relative air humidity is important microclimate parameter of each livestock building. Increased air humidity affects the indoor air quality and, consequently, the animal and workers health. Among others, ventilation rate crucially controls the spatial distribution of air humidity in livestock buildings. This fact motivated authors of this paper to research the influence of air flow rate of under-roof axial fans on relative air humidity distribution over the tied cows house. During a series of performed experiments, six different air flow rates have been maintained in the range between 0 m(3).h(-1) and 48000 m(3).h(-1). Flow rate has been electronically controlled, providing six different rotation rates of two under-roof fans, including the neutral regime (natural ventilation only). Measurements have been performed at four typical height levels (0,5 m; 1,0 m; 1,5 m and 2,0 m), cross-over the three lateral and four longitudinal characteristic building sections. Therefore, the indoor space was adequately covered by 48 measuring points. Comparative analysis of air flow velocities and relative air humilities in certain measuring points showed that this fan setup may provide satisfactory microclimate conditions under adequate operational regime. Certain fan rotation rates are recommended for use, and the third rotation rate step, generating the airflow of 37300 m(3).h(-1) or indoor air exchange level of approximately 25 h(-1), is recommended as the most appropriate.