Heat Rejection process of Carnot Refrigeration

[ChildLikEsper]

Hi there, I just sign up today. I'm curious to know about the energy added/released in a Carnot Refrigeration Cycle. Let's say the problem is like this:

A Carnot Refrigerator used refrigerant-134a as the working fluid. During the heat addition process, a percentage of mass of the refrigerant vaporise.
​

So the question is how do we classify the energy in heat addition process? Is it enthalpy or internal energy? And why?

 

[Chestermiller]

Hi there, I just sign up today. I'm curious to know about the energy added/released in a Carnot Refrigeration Cycle. Let's say the problem is like this:

A Carnot Refrigerator used refrigerant-134a as the working fluid. During the heat addition process, a percentage of mass of the refrigerant vaporise.
​

So the question is how do we classify the energy in heat addition process? Is it enthalpy or internal energy? And why?

You are aware that enthalpy and internal energy are functions of the thermodynamic state of a system, and are inherently different from heat passing through the boundaries of a system, correct?

 

[ChildLikEsper]

You are aware that enthalpy and internal energy are functions of the thermodynamic state of a system, and are inherently different from heat passing through the boundaries of a system, correct?

Can you elaborate on these, I may get these 2 terms confused.

 

[Chestermiller]

Can you elaborate on these, I may get these 2 terms confused.

For an ideal gas, the internal energy is just the sum of the kinetic energies of all the molecules. For a real gas, the internal energy also includes attractive and repulsive energetic interactions between the molecules. The enthalpy is just a convenient parameter to work with in many kinds of problems, and has no fundamental significance. It is defined as H = U + PV.

chet