HEC Electronic
HEC Electronic
The aim is to verify the relationship between the temperature of a SS wire heating element according to the applied viltage. It can be expected that the relationship will not be perfectly linear due to the fact that heat increases the resistance of the wire. The data of the resistance as a function of the temperature of the SS indicates that this variation is very small. So I want to check if in practice this is achieved.
One could quickly conclude that the test is useless since theoretically, the relation should be linear. But an experienced engineer knows that the practical application of something often reveals unexpected problems.
The image above shows an element of SS mounted on a ceramic plate. The total length of the wire is approximately 120mm and a diameter of 0.55mm.The element is raised about 1 mm.
The image above shows the image recorded by a thermal camera after the temperature has stabilized. We can see that the hottest part of the element is at 127 deg. celcius while the ceramic around the element is between 78 and 96 deg. celcius.
The table above shows the measurements made during the experiment. The procedure consisted in imposing a voltage on the element, then in measuring the current and then the temperature. The table was completed by calculating the delta T and V, calculating R and the delta R.
The above curve shows the total resistance of an element as a function of temperature. There is an increase of 25% for temperatures varying from 66 deg. celcius at 232 deg. celcius.
The graph above shows the rate of resistance change as a function of temperature.
The average rate of change is
0.0009702585. The value found in wikipedia is: 0.00094.
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