HVAC Thermodynamics 2

Question 1

What term describes the heat absorbed by a refrigerant as it changes from liquid to vapor at constant temperature?

Accepted Answer

Latent heat of vaporization

Answer

Latent heat of vaporization is the energy absorbed during the phase change from liquid to vapor without a temperature change.

Question 2

Which thermodynamic process occurs when a gas expands without any heat transfer to or from the surroundings?

Accepted Answer

Adiabatic

Answer

An adiabatic process involves no heat exchange with surroundings, so temperature changes are driven entirely by work.

Question 3

In a standard vapor-compression refrigeration cycle, where does the refrigerant absorb heat from the conditioned space?

Accepted Answer

Evaporator

Answer

The evaporator coil absorbs heat from the indoor air, causing the refrigerant to evaporate and cool the space.

Question 4

What is the Coefficient of Performance (COP) of a refrigeration system if it removes 12,000 BTU/hr using 2,000 BTU/hr of work input?

Accepted Answer

6.0

Answer

COP = heat removed / work input = 12,000 / 2,000 = 6.0.

Question 5

Which law of thermodynamics states that heat will not spontaneously flow from a cold body to a hot body?

Accepted Answer

Second Law

Answer

The Second Law of Thermodynamics establishes the natural direction of heat flow and the concept of entropy.

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