Unit of Refrigeration

Definition

The "Unit of Refrigeration" is defined as the Ton of Refrigeration (TR). It represents the rate of heat removal required to freeze one short ton (2,000 lbs) of water at 0°C into ice at 0°C in a duration of 24 hours.

Main Content

1. Thermal Basis of One Ton of Refrigeration

• The latent heat of fusion of ice is approximately 144 BTU/lb (or 334 kJ/kg).
• Converting 2,000 lbs of water to ice requires removing: 2,000 lbs × 144 BTU/lb = 288,000 BTU over 24 hours.

2. Standard Conversion Rates

• To find the hourly rate, divide the total energy by 24 hours: 288,000 BTU / 24 hrs = 12,000 BTU/hr.
• In SI units, 1 Ton of Refrigeration is approximately equivalent to 3.517 kW (kilowatts) of heat removal capacity.

3. Practical Representation

• A 1-ton AC unit means the system is capable of removing 12,000 BTU of heat from a room every hour.
• This unit is a standard industry measurement to help consumers choose the right capacity for cooling spaces of different sizes.

[Heat Removal Visualization]
Heat Source (Room) ----> [Evaporator Coil] ----> Compressor/Condenser
       |                        |                        |
(Warm Air In)            (Heat Absorbed)          (Heat Rejected Outside)

Working / Process

1. Heat Absorption (Evaporation)

• The refrigerant flows through the evaporator coil in a low-pressure liquid state.
• It absorbs the latent heat from the indoor environment, causing the refrigerant to boil and change into a low-pressure vapor.

2. Compression

• The vaporized refrigerant is drawn into the compressor, which increases its pressure and temperature significantly.
• This process requires mechanical energy (electricity) to "pump" the heat from a lower temperature region to a higher one.

3. Heat Rejection (Condensation)

• The high-pressure, high-temperature vapor passes through the condenser coils.
• Outside air or water absorbs this heat, allowing the refrigerant to condense back into a high-pressure liquid to restart the cycle.

Advantages / Applications

• Simplifies the selection of air conditioning and chilling equipment based on room volume and thermal load.
• Essential for designing cold storage facilities, deep freezers, and industrial HVAC systems.
• Allows for the calculation of electricity consumption and cooling efficiency (COP) in engineering projects.

Summary

The unit of refrigeration, known as the Ton of Refrigeration (TR), quantifies the heat removal capacity of a cooling system, standardized as the heat extracted to freeze one ton of water in 24 hours (12,000 BTU/hr). It serves as the primary metric for sizing commercial and residential cooling equipment.

• Key point 1: 1 TR = 12,000 BTU/hr.
• Key point 2: 1 TR = 3.517 kW.
• Key point 3: It is based on the latent heat of fusion of water.
• Important terms to remember: Latent Heat, BTU, Evaporator, Compressor, Ton of Refrigeration.