Assessing a method of incorporating jetting in the HS model and its comm ercial implications

Summary

This study uses a first principles approach based on heat transfer analysis to understand the effect that the jetting of supply air has on heat stress in livestock. The approach relates pen geometry, jet geometry and pen air turnover to a jetting factor, which describes the change in the heat rejection from livestock for a given difference between skin temperature and air wet bulb temperature. A velocity field is calculated from a given supply, pen geometry and jet configuration. A corresponding heat transfer field is then calculated from the velocity field. The heat transfer field is then aggregated into a jetting factor, which considers the difference in heat transfer between the pen under jetting and the pen with only a drift velocity as well as the proportion of the pen area over which the jetting is effective.