313A Refrigeration Fundamentals & Thermodynamics 2

Question 1

On a pressure-enthalpy (P-h) diagram, what does the area under the saturation dome represent?

Accepted Answer

The two-phase (liquid-vapour) mixture region

Answer

The area under the saturation dome on a P-h diagram represents the two-phase region where both liquid and vapour coexist at saturation conditions.

Question 2

What is the coefficient of performance (COP) of a refrigeration system?

Accepted Answer

The ratio of refrigeration effect to the work input to the compressor

Answer

COP is defined as the useful refrigeration effect (heat absorbed at the evaporator) divided by the compressor work input, indicating system efficiency.

Question 3

What happens to the boiling point of a refrigerant as pressure increases?

Accepted Answer

It increases

Answer

As pressure increases, the boiling (saturation) temperature of a refrigerant also increases, which is why high-side pressure corresponds to higher condensing temperatures.

Question 4

In a standard vapour-compression cycle, which process occurs in the compressor?

Accepted Answer

Isentropic compression of refrigerant vapour

Answer

The ideal compressor process is isentropic (adiabatic and reversible) compression, raising both the pressure and temperature of the refrigerant vapour.

Question 5

What is sensible heat?

Accepted Answer

Heat that changes the temperature of a substance without changing its phase

Answer

Sensible heat is heat energy that causes a measurable temperature change in a substance without changing its physical state.

Red Seal HVAC 313A Practice Test

Red Seal HVAC 313A Practice Test

313A Refrigeration Fundamentals & Thermodynamics 2