A method for developing a prediction model of water-side fouling on enhanced tubes

Enhanced tubes have been used widely in the condenser of air conditioning systems with a cooling tower due to their superior heat transfer performance. Both the predicted and real-world performance of these heat exchangers is affected by the build-up of fouling on the heat transfer surfaces. An accurate model to predict the negative impact of fouling on heat transfer of enhanced tubes is important to the HVAC&R industry. In this paper, a method to develop a prediction model of fouling on enhanced tubes is presented. Based on this method, a generalized calculation approach can be developed to determine an appropriate fouling resistance for the application of enhanced tubes in a cooling-tower water heat exchanger application. The combined fouling (precipitation and particle fouling) is considered in this method to make a more accurate prediction. A correlation of the total dry matter concentration with respect to Langelier's Saturation Index (LSI) is proposed to refer to the water quality in the fouling model. The application of this model will allow equipment manufacturers and designers in the HVAC&R industry at large to estimate typical fouling allowances.