Energy
Energy is the capacity of a system to do work where "system" refers
to any physical system, not just a refrigeration system.
Enthalpy
Enthalpy is the total amount of heat in one Lb. of a substance.
It's units are therefore BTU/Lb. The metric counter part is kJ/Kg.
(kilo joules/kilogram)
Entropy
Entropy measures the energy dispersion in a system divided by temperature.
This ratio represents the tendency of energy to spread out, to diffuse,
to become less concentrated in one physical location or one energetic
state. That spreading out is often done by molecules because molecules
above absolute zero always have energy inside of them. That's why
they are incessantly speeding through space and hitting each other
and rotating and vibrating in a gas or liquid. Entropy is measured
in BTU per Lb. per degree change for a substance.
Mollier Charts
Mollier charts are used in designing and analyzing performance of
vapor compression refrigeration systems. Each refrigerant has it's
own chart which is a graph of the Enthalpy of a refrigerant during
various pressures and physical states. Mollier charts are also called
Pressure-Enthalpy diagrams.
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