Question

What is the answer for a standard vapor compression system produces 20 tons of refrigeration using R-12 as a refrigerant while operating between condenser temperature of 41.6°C and an evaporator temperature of -25°C?

Answer 1

To determine the answer, we can use the basic formula for refrigeration capacity in a vapor compression system:

Refrigeration Capacity (in tons) = (Mass flow rate of refrigerant) × (Specific Enthalpy Difference)

Where:

• The mass flow rate of refrigerant is in kg/s.
• The Specific Enthalpy Difference is the difference in specific enthalpy (energy per unit mass) between the evaporator and condenser states of the refrigerant.

To find the Specific Enthalpy Difference, we need to use a refrigerant property table or a refrigerant properties calculator for R-12.

Given that the refrigeration capacity is 20 tons, we can set up the equation:

20 tons = (Mass flow rate of R-12) × (Specific Enthalpy Difference)

Now, let's determine the Specific Enthalpy Difference using the provided temperatures of the condenser and evaporator:

• Condenser Temperature (Tc) = 41.6°C = 314.75 K (Kelvin)
• Evaporator Temperature (Te) = -25°C = 248.15 K (Kelvin)

Once we have the Specific Enthalpy Difference, we can solve for the mass flow rate of R-12:

Mass flow rate of R-12 (in kg/s) = (20 tons) / (Specific Enthalpy Difference)

Plug the temperatures into the table or calculator, find the specific enthalpy values, and proceed with the calculations as outlined above to find the mass flow rate of R-12.