Transactions of the ASABE vol:50 issue:1 pages:265-274
During hot periods, heat loss from non-sweating animals can be improved by fogging water, in order to cool the ambient air and enhance sensible heat dissipation. A dynamic simulation model was used to test control settings for fogging (turning on the system at 1.5 degrees C and 3 degrees C above setpoint temperature, fogging system duty cycle 30 s and continuous) and ventilation (control range 3 degrees C and 6 degrees C, maximum available ventilation rate 32 and 43 air volume changes per hour). The control settings were evaluated by the number of simulated hours in specific temperature-humidity categories, by maximum temperature-humidity index (THI), as well as by the simulated energy use and water consumption of the control strategies. The validation during four growing-finishing periods resulted in an agreement within the accuracy of the temperature and humidity measurements: the difference between simulated and measured values averaged 0.2 degrees C and 3% RH and 0.6 degrees C and 3% RH with and without evaporative cooling, respectively. The efficacy of the fogging system, as measured by reductions in THI, predicted that alert situations were reduced from 13% to 1%, and all dangerous or emergency situations were eliminated. A year-round simulation resulted in water consumption of 2.5 L pig(-1) day(-1) iffogging was used on maximum settings and was lowered by about 25% for an optimized ventilation setting, namely a reduced maximum ventilation rate combined with shifting the temperature at which fogging was turned on. The results demonstrate that water and energy consumption call be reduced clearly without considerable negative effects on THI and indoor air climate.