An optimal misting method for cooling livestock housing

A method to analyze the operation of misting systems to cool livestock housing by minimizing interior Temperature-Humidity Index (THI) is presented. The procedure is shown to be similar to the analysis for evaporative pad cooling, except that interior maximum relative humidity is specified instead of pad efficiency. The minimization of THI is shown to be equivalent to the minimization of interior dry-bulb temperature. If interior heat and moisture loads are neglected, the interior state point can be found at an intersection of outside wet-bulb temperature and inside maximum relative humidity; implications of neglecting these loads are quantified. Comparisons between no cooling, pad cooling, and misting are made to the resultant interior dry-bulb temperature, and to the Gain Reduction Factor (Morrison et al., 1968), for the simplified assumptions of no internal heat loads. The misting system is shown to compare favorably with evaporative pad cooling.