Question

This question related to thermodynamics.

With a throtteling valve in a refrigiration system h₁ = h_2.  

If h₁ = h₂ and only pressure is changed by a throttling valve then why can't an ideal gas be used? Why do refrigerants need to be used?

Answer 1

The main things happens in the isenthalpy process are

Enthalpy remains constant,.

Since enthalpy is proportional to temperature temperature is also remain constant.

There is no work transfer or heat transfer take place.

In throttling process if we use ideal gas the temperature at the exit of condenser and entry of evaporator remain same.

As the temperature of the refrigerants is higher than the fluid which is need to be cooled, so instead of absorbing the from the room refrigerant rejects the heat which is undesirable.

This is the reason ideal gas is not used as refrigerant for throttling process.