A mathematical model of an evaporative pad cooling system to predict the dry-bulb temperature and relative humidity of air exiting the pad, its cooling efficiency and the water requirements for agricultural buildings was derived from first principles using mass and energy balances. The model uses the geometry of the evaporative pad as characteristic parameters and the water temperature, dry-bulb temperature and relative humidity of the outside air as primary boundary conditions. The model was validated with data from wind tunnel tests and field experiments on a closed dairy cattle building using an evaporative pad cooling system. These data also enabled new expressions for heat and mass transfer coefficients of a cellulose cooling pad to be developed and validated. The resulting model accurately predicted the main output variables in the closed dairy cattle building, with the prediction error falling inside the accuracy of the sensors used to measure the environmental variables (±0.5 °C and ±3% for dry-bulb temperature and relative humidity, respectively). The effect of pad water temperature on the output variables was obtained with the developed model, allowing to propose the pad water temperature as an effective manipulated variable for designing an evaporative pad cooling control system. It was found that, for each Celsius degree that the water temperature decreased below the input wet-bulb temperature, the output dry-bulb temperature decreased by 0.7 °C and the output relative humidity increased by 1%.

中文翻译：

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封闭式奶牛舍蒸发垫冷却模型验证

蒸发垫冷却系统的数学模型用于预测离开垫的空气的干球温度和相对湿度、其冷却效率和农业建筑的用水需求，它是从使用质量和能量平衡的第一原理推导出来的。该模型以蒸发垫的几何形状为特征参数，以水温、干球温度和外界空气的相对湿度为主要边界条件。该模型使用来自使用蒸发垫冷却系统的封闭奶牛舍的风洞测试和现场实验的数据进行了验证。这些数据还支持开发和验证纤维素冷却垫的传热和传质系数的新表达式。所得模型准确地预测了封闭奶牛舍内的主要输出变量，预测误差落在用于测量环境变量的传感器精度范围内（±0.5 °C 和±3% 的干球温度和相对湿度） ， 分别）。垫水温度对输出变量的影响是通过开发的模型获得的，允许将垫水温度作为设计蒸发垫冷却控制系统的有效操纵变量。结果表明，水温低于输入湿球温度每降低1摄氏度，输出干球温度降低0.7°C，输出相对湿度增加1%。预测误差落在用于测量环境变量的传感器精度范围内（分别为±0.5°C和±3%的干球温度和相对湿度）。垫水温度对输出变量的影响是通过开发的模型获得的，允许将垫水温度作为设计蒸发垫冷却控制系统的有效操纵变量。结果表明，水温低于输入湿球温度每降低1摄氏度，输出干球温度降低0.7°C，输出相对湿度增加1%。预测误差落在用于测量环境变量的传感器的精度内（分别为±0.5°C和±3%的干球温度和相对湿度）。垫水温度对输出变量的影响是通过开发的模型获得的，允许将垫水温度作为设计蒸发垫冷却控制系统的有效操纵变量。结果表明，水温低于输入湿球温度每降低1摄氏度，输出干球温度降低0.7°C，输出相对湿度增加1%。允许提出垫水温度作为设计蒸发垫冷却控制系统的有效操纵变量。结果表明，水温低于输入湿球温度每降低1摄氏度，输出干球温度降低0.7°C，输出相对湿度增加1%。允许提出垫水温度作为设计蒸发垫冷却控制系统的有效操纵变量。结果表明，水温低于输入湿球温度每降低1摄氏度，输出干球温度降低0.7°C，输出相对湿度增加1%。