Water vapour production of cowshed

Abstract

Whe designing a barn ventilation system and outside partitions important criteria are flows of animal heat and water vapour. There is data in scientific and standard literature on the amount of water vapour produced by animals and the room. But this data is typical of warm barns in which air temperature ranges from 0 to 35° C. In recent decades intensive construction of uninsulated cowshed was started. The average temperatures in uninsulated cowshed of East Europe during the coldest season are about minus 10° C. The work objective is to establish the emission of water vapour in an uninsulated cowshed. A simple method to establish water vapour emission in a cattle house under production conditions was substantiated. The research was made in an uninsulated cowshed with boxes. During the research the indoor and outdoor temperature and relative humidity were measured as well as CO2 concentration in the indoor and outdoor air. According to the measured values specific water vapour emission (amount of water vapour produced by animals and room per animal total heat unit) was calculated, and regression equation relating the flow of water vapour emission with the indoor air temperature was drawn. When temperature is minus 10° C, specific intensity of water vapour emission is 0.054 g/kJ and at plus 10° C it is 0.135 g/kJ. Having analysed the data of water vapour emission in cowsheds with temperatures abowe zero presented by other authors it can be stated that the regression equation drawn reflects the regularity of water vapour emission well. When the specific intensity of water vapour emission is known, the necessary ventilation intensity and the ventilation system parameters can be calculated.