Refrigeration basics — For a real, working refrigerator operating between a cold space and the surroundings, the coefficient of performance (COP) will always be: (Assume steady operation and positive cooling effect.)

Introduction:
The coefficient of performance (COP) of a refrigerator measures how effectively a refrigeration system removes heat from a low-temperature space relative to the work input. Understanding the magnitude and interpretation of COP is fundamental in thermodynamics and HVAC engineering.

Given Data / Assumptions:

• Steady, cyclic operation of a refrigerator.
• Cooling load (Q_L) and compressor work (W_in) are both positive quantities.
• No anomalous definitions; standard engineering sign convention is used.

Concept / Approach:
COP for a refrigerator is defined as COP_R = Q_L / W_in. Because a refrigerator moves heat rather than converting it directly to work, the same unit of work can move multiple units of heat. For any functioning refrigerator, Q_L > 0 and W_in > 0, and in practice Q_L typically exceeds W_in, which makes COP_R greater than 1. Even an ideal (Carnot) refrigerator between finite temperature levels has COP_R > 1.

Step-by-Step Solution:
Define COP_R = Q_L / W_in.Note that refrigeration is a heat-moving process; one unit of work can move several units of heat.Therefore, for any working system, COP_R is a positive number greater than 1.

Verification / Alternative check:
For a Carnot refrigerator, COP_R = T_L / (T_H − T_L). Since T_H > T_L > 0 (absolute scale), the numerator exceeds the denominator’s difference for typical applications, giving a value > 1.

Why Other Options Are Wrong:

• 0 or < 0: implies no cooling or unphysical negative performance.
• < 1: more common for heat engines’ efficiencies, not refrigerators’ COP.
• Exactly 1: would mean Q_L = W_in, which is not typical and only occurs at a very special, inefficient limit.

Common Pitfalls:
Confusing COP with thermal efficiency (always < 1 for heat engines); forgetting COP can be very large for small temperature lifts.

Final Answer:
> 1