Capacity measurement of compressors

[eager]

Can anybody explain how Capacity of Harmetically sealed compressors is measured & what is the theory ehind this?

[taz24]

Do you mean pump testing the compressor?
Or do you mean the Kw capacity of the comp.

Integrals are not hard to test but you do need to fit line tap valves on the suction to check and if you want to do a full test then you need fit one to the discharge as well. You can't do a pump down test but you can check the pumping effiency of the comp. If the back pressure is higher than expected then it could indicate that the comp is not pumping correctly.

Give more details of what specific information you require.

Cheers taz.

[winfred.dela]

Can anybody explain how Capacity of Harmetically sealed compressors is measured & what is the theory ehind this?


Measurement of compressor capacity? - Do you mean the Tons of Refrigeration or KW Refrigeration?

Theory Behind the measurement? - Do you mean the Physics, Thermodynamics?

That's a lot of topics to cover. . . :confused:

Maybe, better ask a teacher or a professor where he can start from high school Physics or Chemistry subject up to the Thermodynamics and a lot more. :rolleyes:

. . . :D

[Samarjit Sen]

The refrigeration capacity of a compressor shall be based on many factors. Some of the major ones are the displacement of the compressor, the Te and Tc at which you would like to operate the compressor and the refrigerant and its properties.

By doing the calculation on this basis you will get a theoritical value which will be quite different from the actual capacity.

It is better to depend on the manufacturers rating charts of the compressors. However it may be noted that the rating charts for the hermitically sealed compressors are based generally on an ambient temperature of 38 Deg. C or may be 32 Deg C, whereas the ambient temperatures in our country is generally 40 to 42 Deg. C. So while trying to judge the capacity it is essential that derating of the capacity be worked out.

[US Iceman]

Hi eager,

I read in your profile you are an engineer, so this should not be too difficult for you.

The compressor ratings are based on refrigerant properties and the rated compressor speed and displacement.

Displacement X Volumetric efficiency = Useful volume flow (usually denoted as volume per unit of time)

Useful volume flow X gas density = mass flow
(again, denoted as mass per unit time)

Mass flow X Delta enthalpy = cooling capacity

The Delta enthalpy is based on the specific operating conditions of the appliance (and the refrigerant used) or the standard rating condition used for these types of appliances.

Most of these ratings are developed by a calorimeter device. See the following for additional details and information.
http://en.wikipedia.org/wiki/Calorimeter