A Multistage Regulation Method for the Pad and Fan Cooling System

The aim of this study was to investigate the abrupt temperature drop problem and its countermeasures of pad and fan cooling system in confined poultry house in summer. The extent and distribution of abrupt temperature drop in a commercial laying-hen house in north China were investigated through field tests. The results showed that over half of poultry house was cooled by more than 5°C (maximum reached 12.4°C) within 25 min after starting the evaporative cooling system under traditional ON/OFF mode. This mode might cause negative effects on layers. In order to attenuate this problem, a multistage regulation method of evaporative cooling system was developed. The water supply pipe was transformed by adding a specially designed water repartition plate to the original water supply system. The water repartition plate can control the watered area of pad. Then four degrees of watered area could be achieved as 1/8, 1/4, 1/2, and the full of pad area, and then gradual cooling process has been achieved. The target temperature was reached gradually through modifying the start temperature and single-cooling range, then a relative long period for chickens to adopt cooling process has been realized. This regulation method has been tested in laboratory. The results showed that gradually watering and cooling works well under multistage regulation. The cooling efficiencies from 1st to 4th stage were 15.84%, 30.53%, 56.67% and 83.70%, respectively, which matched well with prediction. In conclusion, the multistage regulation method was able to, as a new solution, alleviate the problem caused by traditional ON/OFF mode of evaporative cooling system in confined poultry house