In the ejector refrigeration system, the expansion valve is an important device but during the expansion process of the refrigerant, throttling loss occurs and affects the COP. What is the physics behind the throttling loss in an expansion valve?
Dear Shovon
As you know the main principle in the refrigeration cycle is to use the latent heat of evaporation of the refrigerant through the evaporator. Thus, the boiling of refrigerant through the evaporator keeps the evaporator surface nearly constant at the saturation temperature as well as extracts the heat from the space. Since the saturation temperature should be low to meet the application type, then the condenser pressure should be reduced to allow the refrigerant to boil at low temperature. This means destruct the exergy of refrigerant before entering the evaporator.
In the expansion valves pressure drop occurs because the fluid decreases its velocity and this decrease in the seat velocity to increase the diameter of the cross section of the duct.
Q = ρ * V * A
Where:
Q-Mass flow.
ρ-Density of the fluid
V - Speed of the fluid.
A -Area of the transverse section of the duct.
Debrayan Bravo Hidalgo
Thank you for your answer.
we know already about pressure drop along with the expansion valve but what is the link between pressure drop and throttling loss?
Abdul Hadi N Khalifa
Dear sir,
Thank you for your answer.
As we already know there is exergy destruction by the throttling process.
Also, throttling process is isenthalpic. Besides, there is an entropy generation in this process. this entropy generation will be associated with throttling loss. But how exergy destruction, pressure drop are linked with throttling loss?
I'm waiting for your kind reply.
Thank you so much.
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