Abstract: The quality of heat exchanger is very important， it can improve the operational performance of the entire system and save energy. For the outlet water control system，uses normalized method to treat the fuzzy control′s error E and differential error Ec ，makes the E ， Ec and ΔU in the same domain， carries out simulation based on MATLAB environment and obtains the experimental results.

Key words: fuzzy control, normalization, simulation, heat exchanger, temperature control