What does “one tonne of refrigeration” (1 TR) signify in conventional refrigeration units?

Introduction / Context:
“Ton of refrigeration” is a traditional capacity unit in HVAC and refrigeration. It originates from the rate of heat removal required to freeze or melt ice and remains widely used alongside kW and TR-tonne conversions in sizing chillers and package units.

Given Data / Assumptions:

• Reference is “from and at 0°C.”
• Latent heat of fusion of ice ≈ 334 kJ/kg.
• One metric tonne = 1000 kg.

Concept / Approach:
One TR is defined as the rate of heat removal equivalent to melting 1000 kg of ice at 0°C in 24 hours. Heat required = 1000 * 334 kJ = 334,000 kJ per 24 h. Dividing by time gives the standard rate in kJ/min or kW.

Step-by-Step Solution:

Verification / Alternative check:
Both 3.517 kW (short-ton basis) and ~3.87 kW (metric-ton basis) appear; exam contexts often adopt the older 211 kJ/min standard, matching the option text.

Why Other Options Are Wrong:

• Machine mass or refrigerant mass have no direct link to TR.
• “One tonne of water can be frozen” lacks the 24-hour rate basis.
• 1 kW is not equal to 1 TR.

Common Pitfalls:
Mixing metric versus short-ton definitions; always check the convention used in the problem statement.

Final Answer:
Melting of one tonne of ice from and at 0°C in 24 hours, equivalent to about 210 kJ/min of refrigeration effect