Definition of 1 tonne of refrigeration (1 TR): What is the corresponding heat removal capacity expressed in kJ per minute?

Introduction / Context:
“Tonne of refrigeration” is a legacy but still common capacity unit in HVAC&R. Converting 1 TR into consistent SI energy-rate units is essential for load calculations and equipment comparison.

Given Data / Assumptions:

• By definition, 1 TR = heat required to freeze 1 short ton (2000 lb) of water at 0 °C into ice at 0 °C in 24 hours.
• Latent heat of fusion of water ≈ 334 kJ/kg.
• 1 short ton = 2000 lb ≈ 907 kg.

Concept / Approach:
Compute total heat removed and divide by time to obtain power. Then convert to kJ/min for direct comparison with the options.

Step-by-Step Solution:
Mass m ≈ 907 kg.Total heat Q_total = m * L_f ≈ 907 * 334 kJ ≈ 302,938 kJ.Time = 24 h = 24 * 60 = 1440 min.Rate Q_dot = Q_total / time ≈ 302,938 / 1440 ≈ 210.4 kJ/min.Therefore, 1 TR ≈ 210 kJ/min ≈ 3.517 kW.

Verification / Alternative check:
Using the well-known identity: 1 TR = 12,000 Btu/h ≈ 3.517 kW; 3.517 kW * 60 s/min ≈ 211 kJ/min, consistent with 210 kJ/min by rounding.

Why Other Options Are Wrong:

• 21 and 351.7 kJ/min: 21 is a factor-of-10 error; 351.7 corresponds to 5.86 kW, not 1 TR.
• 420 and 620 kJ/min: Overstate the capacity (about 2 TR and 3 TR).

Common Pitfalls:
Confusing short ton and metric ton; assuming 1 TR equals 4 kW exactly (it does not).

Final Answer:
210 kJ/min