Mathematical modeling of a multi-stream brazed aluminum plate fin heat exchanger

Abstract

The need for small size and lightweight heat exchangers in many applications has resulted in the development of many heat transfer surfaces. This type of heat exchanger is much more compact than can be practically realized with circular tubes. In this work a steady-state mathematical model that representing one of the plate fin heat exchangers enclosed in cold box of an ethylene plant has been developed. This model could evaluate the performance of the heat exchanger by predicting the outlet temperatures of the hot and cold streams when the inlet conditions are known. The model has been validated by comparing the results with actual operating values and the results showed good agreement with the actual data. Sensitivity analysis was applied on the model to illustrate the main parameters that have the greatest influence on the model calculated results. The sensitivity analysis showed that the hot stream outlet temperature is more sensitive to cold streams inlet temperatures and less sensitive to hot stream inlet temperature and thermal resistance (fouling), while the cold stream outlet temperature is more sensitive to cold streams inlet flow rate and less sensitive to fouling.