Evaporative Cooling of Power Cables - Prediction of Thermal Performance with Load Changes

The transient thermal performance of evaporatively cooled cable systems utilising the change of phase of Freon 12 is investigated. Methods for computing the temperature-time movements with changes in load or loss of coolant flow are reported. For the internal duct system the change in conductor temperature is seen to be rapid with a step change of load as it is with a loss of coolant. A study, of various cable loading indicates that at an intermediate cable loss the coolant flow rate is a maximum and that flow is maintained over a wide range of loads.