Abstract: A distributed parameter model is developed for predicting the performance of a horizontal-tube falling-film evaporator. In this model, the variation of heat transfer performance along the tube length and array, as well as the effect of the dry patch on the performance are considered. The model is applied to predicting the performance of a commercial falling film evaporator, and the influences of bundle layout, pass layout, refrigerant mass flow rate and the flooded level of refrigerant on the evaporator performances are studied. The results show that the simulation result agrees well with the experimental data, and it is possible to decrease or avoid the dry patch area on the tube bundle and therefore improve the evaporator performance by rationallly designing the layout of the tube bundle and the flooded level of the refrigerant.

Key words: Distributed parameter model, Dry patch, Falling film evaporator