Can I use P1/P2=(T1/T2)y/y-1 to find the temperature when we pressure liquid refrigerant, for example liquid propane?
Yes, you can use the equation P1/P2=(T1/T2)y/y-1 to find the temperature when pressure changes for a given substance. This equation is based on the relationship between pressure (P) and temperature (T) for an ideal gas, known as the ideal gas law. However, it is important to note that this equation assumes that the substance behaves ideally and follows the ideal gas law.
To use this equation to find the temperature when pressure changes for liquid propane, you will need to know the initial pressure (P1), initial temperature (T1), final pressure (P2), and the value of the heat capacity ratio (y) for propane.
The heat capacity ratio (y) is a property that depends on the nature of the substance and is typically provided in the literature for specific substances. For propane, the heat capacity ratio can be assumed to be approximately 1.12.
Once you have the values of P1, T1, P2, and y, you can plug these values into the equation P1/P2=(T1/T2)y/y-1 and solve for T2, which represents the final temperature.
Here's an example calculation:
Suppose you have an initial pressure of 2 atm (P1), an initial temperature of 20°C (T1), and a final pressure of 4 atm (P2). The heat capacity ratio (y) for propane is assumed to be 1.12.
You can rearrange the equation P1/P2=(T1/T2)y/y-1 to solve for T2:
(P1/P2)(y-1)/y = T1/T2
Plugging in the given values:
(2/4)(1.12-1)/1.12 = (20/T2)
Simplifying the equation:
0.56/1.12 = 20/T2
0.5 = 20/T2
Cross-multiplying and solving for T2:
T2 = 20/0.5
T2 = 40°C
Therefore, the temperature when the pressure changes from 2 atm to 4 atm for liquid propane would be approximately 40°C.