Question

In actual practice, one ton of refrigeration is taken as equivalent to __________.

• A. 3.5 Kw/s
• B. 2.5 Kw/s
• C. 1 Kw/s
• D. 4.5 Kw/s

Hint:

Remember the standard conversion factor: \(1\text{ TR} \approx 3.5\text{ kW}\) (or \(\text{kJ/s}\)), which represents the basic unit of cooling capacity in industrial food cold storages.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
In food cold-storage engineering and refrigeration, the capacity of a refrigeration system is measured in "Tons of Refrigeration" (TR).
One Ton of Refrigeration is defined as the rate of heat extraction required to freeze one short ton (2000 lbs) of water at \(0^{\circ}\text{C}\) into ice at \(0^{\circ}\text{C}\) in 24 hours.

Step 2: Detailed Explanation:
Let us mathematically derive the energy equivalent of 1 TR:
The latent heat of fusion of ice is approximately \(335\text{ kJ/kg}\) (or \(144\text{ Btu/lb}\)).
The mass of 1 short ton is:
\[ m = 2000\text{ lbs} \approx 907.18\text{ kg} \] The total heat extraction required to freeze this mass of water in 24 hours is:
\[ Q = m \cdot L_f = 907.18\text{ kg} \times 335\text{ kJ/kg} \approx 303,905\text{ kJ} \] To find the rate of heat extraction per second (Power in kW):
\[ \text{Rate} = \frac{303,905\text{ kJ}}{24\text{ hours} \times 3600\text{ seconds/hour}} \approx \frac{303,905}{86,400} \approx 3.517\text{ kJ/s} = 3.517\text{ kW} \] In standard refrigeration practice, this value is rounded and taken as equivalent to \(3.5\text{ kW}\) (the unit "Kw/s" in the exam paper is a minor typo representing \(\text{kJ/s}\) or \(\text{kW}\)).

Step 3: Final Answer:
Therefore, one ton of refrigeration is equivalent to 3.5 kW (Kw/s).