How to Calculate Refrigerant Amounts

Refrigerants keep areas cool.
••• Chris Ware/Valueline/Getty Images

Heat pumps transfer energy by forcing a refrigerant through differing pressures. The refrigerant absorbs latent heat of vaporization when it evaporates and releases it elsewhere when it liquefies. Each refrigerant has its own heat transfer rate, a value that describes how much heat it absorbs per unit weight. Specifications typically state this value using the standard scientific unit of kilojoules per kilogram (kj/kg). Simple conversions apply this transfer rate to construction and manufacturing measurements.

    Multiply your heat transfer requirement, measured in British Thermal Units, by 1.055 to convert it to kilojoules. If you must move, for instance, 250,000 BTUs in a given amount of time: 250,000 x 1.055 = 263,750 kj.

    Divide this amount of heat by the refrigerant's heat transfer rate. If the refrigerant moves, for instance, 170 kj/kg, then: 263,750 / 170 = 1,551 kg.

    Multiply this weight by 2.2 to convert it to pounds: 1,551 x 2.2 = 3,412 lb.

    Divide this weight by the number of cycles the system will go through during the time period. If if will cycle the refrigerant, for instance, 20 times: 3,412 / 20 = approximately 170 pounds. The system therefore needs 170 pounds of refrigerant.

Related Articles

How to Convert CMH to BTU
How to Calculate Refrigerant Capacity
How to Convert Kilojoules to Kilocalories
How to Convert GPM to Cooling Rate in Tons
How to Convert Specific Gravity in Weight
How Do You Convert HSFP to COP?
How to Figure GPM Water Flow on an Existing Chiller
How to Convert MBH to Tons
How to Calculate the Amount of Condensate Per Amount...
How to Convert Gallons, Quarts, Pints and Cups
How to Convert HP to BTU/hr
How to Calculate the Mass of a Moving Object
How to Convert BTU to KW
How to Convert Horsepower to Thrust
What Is the Unit for Enthalpy?
How to Convert Kilopascals to Joules
How to Measure Time in Hundredths of an Hour
How to Calculate Heat of Sublimation