Refrigeration vs. heat pumping — From a thermodynamic standpoint, a refrigerator can be viewed as which of the following devices?

Difficulty: Easy

Correct Answer: A heat pump (moving heat from low to high temperature region)

Explanation:


Introduction:
Refrigerators and heat pumps share the same thermodynamic cycle operating in reverse relative to heat engines. The difference is in the objective: cooling a space versus heating a space.



Given Data / Assumptions:

  • Device absorbs heat from a cold reservoir and rejects it to a hot reservoir.
  • Work input drives the cycle.
  • Steady, cyclic operation.


Concept / Approach:
A heat pump is any device that uses work to transfer heat from a lower to a higher temperature. A refrigerator is therefore a heat pump whose useful effect is the heat removed from the cold space (Q_L). When the useful effect is the heat delivered to the hot space (Q_H), we emphasize the “heat pump” role with COP_HP = Q_H / W_in. The same physical machine can be called a refrigerator or a heat pump depending on which output is desired.



Step-by-Step Solution:
Identify function: move heat against its natural gradient using work.Classify: this is the definition of a heat pump.Conclude: a refrigerator may be termed a heat pump (specialized for cooling duty).



Verification / Alternative check:
Carnot refrigerator and Carnot heat pump share the same reversed Carnot cycle; the performance expressions differ only in whether Q_L or Q_H appears in the numerator.



Why Other Options Are Wrong:

  • Heat engine converts heat to work; a refrigerator consumes work to move heat.
  • Carnot engine (forward) is not a refrigerator; the reversed Carnot cycle is.
  • “None” and “battery” options do not match thermodynamic definitions.


Common Pitfalls:
Thinking heat pumps are only for space heating; in fact, refrigerators are a type of heat pump.



Final Answer:
A heat pump (moving heat from low to high temperature region)

More Questions from Chemical Engineering Thermodynamics

Discussion & Comments

No comments yet. Be the first to comment!
Join Discussion