Centigrade VS Kelvin

[A.Mortezania]

Dear Friends,

Would you please tell me in most of Europe compressor catalogue, Why when they talk about evp. and cond. Temperature they say centigrade (C) but when they want to talk about Delta T , For example sub-cooling or super-heat they mention this by Kelvin (K). for example 5K superheat.

Sincerely yours.

[Brian_UK]

When measuring the temperature of something we use the Celsius term because we are referring to a point in a temperature range that we know and understand.

The range of 0 to 100 degrees came from Centigrade but we now use the term Celsius to describe the actual degree within that range. Obviously we also use the negative range as well.

With a figure from the Celsius such as 20 degrees we would expect to feel comfortably warm. At 10 degrees C we would feel a bit cooler.

If we now change to saying that the superheat reading is 10 degrees C does that mean that the superheat is feeling cooler?

No, a superheat reading needs to tell us that there is a difference between two temperature points at an arbitrary temperature so we use the temperature term Kelvin.

For example you could have 5K superheat at a suction temperature of 15C and you could also have 5K at -23C.

So we use the different terms to describe to different meanings using the same Centigrade scale.

[Rob White]

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To avoid confusion, most measurements are done in metric centigrade but when we measure difference we do that in Kelvin. Delta T in Kelvin avoids confusion, for example if I said an evaporator had an air off at +5 with a 10K difference, you should know that the evaporating temp would be -5.

Rob

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[A.Mortezania]

.

To avoid confusion, most measurements are done in metric centigrade but when we measure difference we do that in Kelvin. Delta T in Kelvin avoids confusion, for example if I said an evaporator had an air off at +5 with a 10K difference, you should know that the evaporating temp would be -5.

Rob

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Thanks Rob and Brian_UK.

[Josip]

Hi,

Kelvin is related to thermodynamic energy ... you need to research that for yourself ... maybe to start here

https://en.wikipedia.org/wiki/Equipartition_theorem


Centigrade is related only to state of water freezing 0*C or evaporating 100*C ... it has nothing with energy ...
good explanation by Brian_UK ... it is something we are familiar with ... like feeling hot or comfortable or cold ..



Best regards, Josip