Here we are not prepared to discuss the problem of how to design a radiator, but to discuss a radiator cooling effect is relatively good question. In fact, this is a junction temperature of the measurement problem, if we can measure the junction temperature of a radiator that can be achieved, then not only can compare the radiator cooling effect, but also know that using this radiator can achieve led high power bulbs life.
Junction temperature appears to be a temperature measurement, but the junction temperature to be measured inside the led high bay, we can not take a thermometer or thermocouple into the PN junction to measure its temperature. Of course, the case temperature can still be measured with a thermocouple, and then given thermal resistance Rjc (junction to case), one can calculate the junction temperature. But after a good radiator is installed, the problem becomes complicated by the Because usually the led high power bulbs is soldered to the aluminum plate, aluminum plate installed on the radiator, if only measuring the temperature of the radiator shell, then to calculate the junction temperature must know a lot of thermal resistance value of. Including Rjc (junction to case), RCM (housing to the aluminum plate, which should include the thermal resistance of the film printed version), Rms (aluminum plate to the radiator), of Rsa (radiator to the air), which has a data inaccurate will affect the accuracy of the test. Figure 3 shows a schematic diagram of the LED to the various thermal resistance of the radiator. Merged a lot of thermal resistance, and its accuracy is more restricted. In other words, the radiator surface temperature to infer from the measured junction temperature accuracy is even worse.