Predicting 3D Spatial Temperature Uniformity inStorage Systems Using an Airflow Pattern Sensor

摘要

In many biological processes (storage systems, agricultural buildings, breeding of eggs,industrial malting processes…) a perfectly mixed airspace with a uniform 3D temperature distributionhas to be achieved. Spatial temperature gradients, which exceed an acceptable gradient, have anegative effect on quality and efficiency of the process. The temperature uniformity index (UI) wasused to quantify the spatial homogeneity of temperature in a ventilated airspace by using a 3D-grid of36 temperature sensors. UI is defined as the volumetric part (in %) of the airspace with atemperature between the limiting values of Tav-?T and Tav+?T, where Tav is mean room temperatureand ?T is the acceptable temperature deviation. The calculation of UI with 3D temperaturemeasurements within the process room is difficult in real systems. An airflow pattern sensor,developed to control airflow pattern in ventilated buildings, measures temperature distribution at theposition of air inlet opening(s). The sensor consists of number of temperature sensors on an arc,positioned vertically at the upstream position of the inlet(s) to measure the 2D inlet temperaturedistribution. This sensor was used to predict UI at different c onditions. The objective of this study wasto investigate the relation between inlet temperature distribution and uniformity index for differentventilation rates and inlet flap positions in a room filled with empty and potato filled cases. Linearregression analysis was used to model the UI from the temperature measurements obtained from theairflow pattern sensor. Using ten temperature sensors at the inlet, R-square value of 0.81 and 0.73was found with an average standard error of 5 and 7 % for UIs from 15 to 96 %, in a room filled withempty and potato filled cases, respectively. Results showed that inlet temperature measurementscould be used to predict uniformity of temperature in a mechanically ventilated space.