Question 1

The sensing bulb on a TEV is located at which part of the refrigeration system?

Accepted Answer

The sensing bulb of a Thermostatic Expansion Valve (TEV) is located at the outlet of the evaporator to sense the temperature of the refrigerant as it exits, allowing the valve to adjust the flow of refrigerant into the evaporator accordingly.

Question 2

The basic air conditioning system is made up of which four components?

Accepted Answer

The basic air conditioning system is made up of four components: the compressor, condenser, evaporator, and metering device. The compressor compresses the refrigerant gas, sending it to the condenser, which removes heat from the refrigerant and turns it into a high-pressure liquid. The liquid refrigerant goes to the metering device, which regulates the flow of refrigerant into the evaporator. In the evaporator, the refrigerant absorbs heat from the air and turns into a low-pressure gas, which returns to the compressor to start the cycle again. Choice A includes a receiver, which is not typically part of a basic air conditioning system. Choice B includes an accumulator, which is only used in certain types of systems. Choice D includes a filter drier, which is an important component for removing moisture and contaminants from the refrigerant but is not one of the four main components of the system.

Question 3

Which refrigerant used in residential air conditioning has operating pressures that are about 40% to 70% higher than that of R-22?

Accepted Answer

R-410A has operating pressures that are about 40% to 70% higher than that of R-22, making it the best choice for residential air conditioning systems. R-22 is being phased out due to its harmful effects on the environment. R-134a is commonly used in automotive air conditioning systems, and R-12 is an older refrigerant that is no longer in use due to its ozone-depleting properties.

Question 4

An evaporator can also dehumidify the air in a building.

Accepted Answer

As the evaporator coil absorbs heat and moisture from the air, it can also remove excess humidity, thus dehumidifying the air.

Question 5

Which component in a refrigeration system performs the actual cooling or refrigeration?

Accepted Answer

The evaporator is the component in a refrigeration system that performs the actual cooling or refrigeration by absorbing heat from the area that needs to be cooled. The other components (compressor, condenser, and metering device) all play important roles in the refrigeration cycle, but do not directly perform the cooling.

Question 6

Refrigerant can exist as both a liquid and vapor simultaneously.

Accepted Answer

This phenomenon is known as saturation and occurs at the saturation point or the boiling point of the refrigerant. At this point, the refrigerant can exist as both liquid and vapor in equilibrium.

Question 7

Which component in a refrigeration system is responsible for raising the pressure and temperature of the vapor refrigerant that leaves the evaporator?

Accepted Answer

The compressor is responsible for raising the pressure and temperature of the vapor refrigerant that leaves the evaporator. This is necessary to prepare the refrigerant for condensation in the condenser.

Question 8

Which component in a refrigeration system is responsible for reducing the pressure in the system?

Accepted Answer

The metering device, also known as the expansion valve or capillary tube, is responsible for reducing the pressure in the refrigeration system by restricting the flow of refrigerant from the high-pressure side to the low-pressure side. This is necessary for the refrigerant to evaporate in the evaporator and absorb heat from the surrounding environment, which cools the space or product being refrigerated.

Question 9

The refrigeration process can best be described as the transferring of heat from an objectionable location to a place where the addition of this heat has __________ on the surrounding conditions.

Accepted Answer

The purpose of refrigeration is to remove heat from a space, so it would not make sense if adding this heat had a great or moderate effect on the surrounding conditions. The best choice is B because the heat transferred has little or no effect on the surrounding conditions.

Question 10

Higher efficiency condensers can operate with saturation temperatures as low as ____ degrees F higher than the ambient air.

Accepted Answer

Higher efficiency condensers can operate with saturation temperatures as low as 20 degrees F higher than the ambient air, which allows them to effectively condense refrigerant vapor at lower temperatures, improving the system's overall efficiency.

Question 11

The refrigerant is pumped from the compressor to which component?

Accepted Answer

The refrigerant is pumped from the compressor to the condenser, where it is cooled and condensed into a liquid before being sent to the evaporator.

Question 12

It is possible for a refrigerant to absorb heat at a low temperature and reject heat at a higher temperature.

Accepted Answer

This is the basic principle of how a refrigerator or air conditioning system works. The refrigerant absorbs heat from the indoor air or food and then releases it to the outdoor air, even if the outdoor temperature is hotter than the indoor temperature. This is achieved through the use of a compressor, condenser, and evaporator in the refrigeration cycle.

Question 13

As the pressure of a saturated refrigerant increases, its temperature decreases.

Accepted Answer

As the pressure of a saturated refrigerant increases, its temperature also increases. This is because the pressure-temperature relationship in a saturated refrigerant follows the Clausius-Clapeyron equation, which states that an increase in pressure leads to an increase in temperature, and vice versa.

Question 14

Which type of compressor can be identified by its cylindrical shape and the fact that the discharge line is located in the center at the very top of the compressor?

Accepted Answer

Rotary compressors are characterized by their cylindrical shape, and the discharge line is typically located at the center at the top, distinguishing them from other types of compressors.

Question 15

Although it is no longer used in the manufacturing of new air conditioning systems, the number of existing systems using __________ is large, so technicians will be encountering this refrigerant for many years to come.

Accepted Answer

R-22 was commonly used in air conditioning systems before it was phased out due to its negative impact on the environment. However, since many existing systems still use R-22, technicians will continue to encounter it for years to come.

Question 16

Which type of compressor utilizes pistons, cylinders, and valves to accomplish the compression of the refrigerant?

Accepted Answer

Reciprocating compressors are the type of compressors that utilize pistons, cylinders, and valves to accomplish the compression of the refrigerant. Therefore, option A is the correct choice. Rotary, screw, and scroll compressors use different mechanisms for compression.

Question 17

Which two types of heat can an evaporator remove from the air?

Accepted Answer

An evaporator can remove latent heat through the process of evaporation and sensible heat through the process of cooling the air. Choice A (radiant and conduction) is not applicable as an evaporator is not designed to remove heat through these processes. Choice B (sensible and radiant) is partly correct, but the primary function of an evaporator is to remove latent heat through evaporation. Choice D (superheat and subcooling) is not relevant to the function of an evaporator as it is a process associated with refrigerant temperature and not air temperature.

Question 18

The amount of heat added to a substance after it has been vaporized is called ____.

Accepted Answer

The term "superheat" refers specifically to the amount of heat added to a substance after it has already been vaporized. "Subcooling" refers to the opposite process, where a substance is cooled below its boiling point before it vaporizes. "Latent" refers to the energy required to change the state of a substance (i.e. from solid to liquid, liquid to gas), not the heat added after that change has occurred. "Radiant" refers to energy transmitted in the form of electromagnetic radiation, which is not directly related to the heat added to a substance.

Question 19

Which component in a refrigeration system rejects the heat from the system?

Accepted Answer

The condenser is the component in a refrigeration system that rejects the heat from the system. It condenses the refrigerant vapor into a liquid and releases the heat absorbed in the evaporator to the environment outside of the system.

Question 20

Which type of compressor is reliant on the production of two perfectly machined spirals?

Accepted Answer

The scroll compressor relies on the production of two perfectly machined spirals to compress the refrigerant.

Quiz 2: The Refrigeration Process