Performance model for small scale indirect evaporative Cooler.

Indirect evaporative cooling an efficient and cheap way to reduce the heat load in a building. For an innovative small scale evaporative cooler (400 m3/h) a model is made to predict the outlet temperature and cooling capacity for different environmental conditions in order to estimate the seasonal heat load reduction. The cooler is a compact counter flow heat exchanger with louver fin geometry on either side; the secondary side is coated with a water absorbing material. Due to the direct evaporation from the surface and the counter flow operation outlet temperatures below the wet bulb temperature can be achieved. The model uses Chilton & Colburn approximation for the evaporation, an approximation for the j-factor as found by Chang and Wang. The resulting model is based on estimated geometry properties and predicts the outlet temperature for given inlet conditions an airflow rates. The model predicts an over performance of the output temperature. For the inlet temperature below 24°C there a 20 % overshoot of the model, for higher inlet temperatures the overshoot is less than 10%