Alternative method for assessing the effectiveness of heat exchangers

Abstract

This article discusses an automated system for monitoring the thermal effectiveness of hydrogenerator heat exchangers (water-air). The proposed calculation methodology eliminates the need to measure the outlet air temperature (the heat exchanger hot working fluid) and allows for continuous monitoring of the exchanger even during online cleaning interventions not requiring interruption of the generation. A computational code is proposed to solve the non-linear equations governing the mechanisms of heat transfer between the working fluids. The technique was validated based on analysis of the uncertainties associated with measurements performed over an 11-month monitoring period. The results of the study reveal that the conventional method, which does require measurement of the outlet air temperature, can introduce errors of the order of 30% in the calculation of the exchanger effectiveness. The suggested procedure proved to be an effective tool for managing the cooling system of hydrogenerators.

Keywords

• Heat exchanger effectiveness
• Hydrogenerator
• Measurement uncertainty