Experiment on maintenance of temperature difference between of inlet and outlet cooling water in condenser was conducted to evaluate electric power consumption of the variable speed pump used inverter for refigerator oh the tuna long line fishing boat. The results showed that the temperature difference of inlet and outlet cooling water in condenser was kept Within 1℃, although sea water temperature under operation changed with the range from 10 to 30 ℃. In this case, the system could save 6.8 kW in electric power consumption, the rate of energy saving indicated 86 %.
