Guess this is about temperature distribution in the compressor casing, during normal operation and transients such as cool down kinetics. That means looking at the thermal expansion and stress induced by the thermal gradients, and could be used for assessing:
- stress on nozzles and connections,
- maximum discharge temperature vs. casing max allowable temperature,
I guess it can also cover
- casing cool down time, for example during stand still and verification of condensation issues;
In some application cases the casing may need to be insulated because the gas is not enough superheated and can condense at the casing wall location, especially in cold climate; so jacketting around casing could be used together with heat tracing. In this case a thermal study is also relevant for sizing and determining the insulation.
Finally, remember that the amount of heat losses through the casing will affect the performance (efficiency) of the machine. A completely thermally insulated casing will have impact on performance specifically efficiency will deviate from the polytropic case and get closer to the adiabatic one.
The study should be normally done by vendor. But I also have seen case where Vendor prefered not to take responsibility of it.
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