RETA BOOK 2 EXAM PRACTICE TEST QUESTIONS AND
CORRECT ANSWERS 2026-2027!!
Density
Which of the following factors listed does NOT affect heat transfer?
Wood
Which of the following is an example of a poor conductor of heat?
The number of btus that will pass in one hour through a material 1" thick with the
area of 1ft sq if the temperature difference from one side to the other is 1f
What is thermal conductivity (k)?
Warm dry air
Which is NOT a common source of fouling of a heat exchange surface?
The higher the k-factor, the greater the thermal conductivity
Which statement is true
There is no impeding substance such as ice, dirt, or oil on the surfaces of the
heat exchanger tubes.
Optimum U-factor for the given material that the heat exchanger is made of
results when?
It is reduced
What happens to the cooling capacity when airflow is decreased across heat
exchange surfaces?
Centrifugal fans are quieter
What is the advantage centrifugal fans have over propeller fans?
Cannot change the k-factor of the metal but has some control of the overall U-
factor for the evaporator as a unit.
The operating engineer
Evaporator size
What is a limiting factor of evaporator capacity that the operator cannot control?
Periodically remove oil from the oil collection points
What is the best way to keep an evaporator from being affected by oil build-up?
Cleanliness of the evaporator
The effectiveness of a heat transfer surface depends on several factors. One
factor the operator has control over is?
They require less motor horsepower per CFM
One advantage of using axial type fans is?
Increased U-factor
Which of the following is NOT a result of scale build-up on a condenser coil?
,The rate of heat that is transferred will be cut in half
If R-value is doubled, what will happen to the heat transfer rate, assuming the
temperature difference and the area do not change?
The capacity of the evaporator is increased by 50%
What happens to the theoretical capacity of an evaporator in a 0f freezer if the
ammonia evaporating temperature is dropped from -10f to -15*f
Cause efficiency loss and potential damage to the suction line
Damaged insulation on the suction line in an ammonia refrigeration system will?
The temperature at which moisture will condense out of the air
The dew point is?
An indication of the sensible heat content of the air
The dry bulb temperature is?
An increase in the infiltration load on a refrigeration system
A high relative humidity will cause?
Requires more evaporative condenser capacity if it is relatively high
Wet bulb temperature?
Is heavier than warm air
Cold air?
Air that has zero moisture content
Dry air?
The air has less ability to absorb moisture
Higher wet bulb temperatures reduce evaporative condenser capacity because?
The total heat content of the dry air and the moisture in the air
On a psychrometric chart, enthalpy is used to describe?
Absolute water content stays fixed even if the temperature of the air changes
The difference between absolute water content in air and relative humidity is?
The dry bulb, wet bulb, and dew point temperatures are the same
At 100% relative humidity?
The wet bulb temperature will increase
At a given dry bulb temperature, if the relative humidity increases?
Reduced absolute humidity in the room and higher operating costs
Reducing the evaporating temperature of an air unit from 45f to 28f will cause
The total internal heat energy content of a system plus the product of its volume
multiplied by its pressure
Enthalpy is?
Illustrates the change of condition and heat content of a pound of refrigerant at
different points of the refrigeration cycle
The mollier diagram?
Subcooled liquid, a mixture of saturated liquid and vapor, saturated vapor.
The mollier diagram has three regions of refrigerant conditions which are?
, Psia
The pressure scale on an enthalpy diagram typically used in the U.S. is expressed
in?
The heat quantity in a pound of saturated vapor is greater than the heat quantity
in a pound of saturated liquid at the same pressure
In a refrigeration system (at normal refrigeration pressures), how does the heat
content of a pound of saturated vapor compare to the heat content of a pound of
saturated liquid
The refrigerant has rejected the latent heat of condensation and is a saturated
liquid
Moving across the mollier diagram from right to left, what has occurred when the
refrigerant reaches the line in the left side of the mixed liquid and vapor region?
Horizontal because change of state of a refrigerant at constant pressure is done
at a constant temperature.
The temperature lines within the saturated mixture some of an enthalpy diagram
are?
Is saturated liquid
The boundary line between the subcooled liquid region and the saturated mixture
region?
Is saturated vapor
The boundary line that separates the saturated mixture region and the
superheated vapor region?
Heat of compression
A simple refrigeration cycle plotted on the enthalpy diagram illustrates why a
condenser must reject more heat Than just the heat absorbed in the evaporator
because of?
Does not change
A vertical change (change of pressure) in the subcooled liquid region or in the
saturated mixture region ______________ the enthalpy of the refrigerant at that
point
The evaporator (DX), suction lines, compressors
Superheat enters the system at?
There is less flash gas formed for the low stage compressor to handle
In a two-stage system, subcooled liquid entering the evaporator generally
enhances the performance of the system because?
The new suction line on the roof was not insulated, and the condensers are
sealed
As the operator of a refrigeration plant, the owner indicates that the power
consumption (kwh) is up 15% over this time last year. The owner wants to know
why there is such a huge increase in consumption. The cause is?
CORRECT ANSWERS 2026-2027!!
Density
Which of the following factors listed does NOT affect heat transfer?
Wood
Which of the following is an example of a poor conductor of heat?
The number of btus that will pass in one hour through a material 1" thick with the
area of 1ft sq if the temperature difference from one side to the other is 1f
What is thermal conductivity (k)?
Warm dry air
Which is NOT a common source of fouling of a heat exchange surface?
The higher the k-factor, the greater the thermal conductivity
Which statement is true
There is no impeding substance such as ice, dirt, or oil on the surfaces of the
heat exchanger tubes.
Optimum U-factor for the given material that the heat exchanger is made of
results when?
It is reduced
What happens to the cooling capacity when airflow is decreased across heat
exchange surfaces?
Centrifugal fans are quieter
What is the advantage centrifugal fans have over propeller fans?
Cannot change the k-factor of the metal but has some control of the overall U-
factor for the evaporator as a unit.
The operating engineer
Evaporator size
What is a limiting factor of evaporator capacity that the operator cannot control?
Periodically remove oil from the oil collection points
What is the best way to keep an evaporator from being affected by oil build-up?
Cleanliness of the evaporator
The effectiveness of a heat transfer surface depends on several factors. One
factor the operator has control over is?
They require less motor horsepower per CFM
One advantage of using axial type fans is?
Increased U-factor
Which of the following is NOT a result of scale build-up on a condenser coil?
,The rate of heat that is transferred will be cut in half
If R-value is doubled, what will happen to the heat transfer rate, assuming the
temperature difference and the area do not change?
The capacity of the evaporator is increased by 50%
What happens to the theoretical capacity of an evaporator in a 0f freezer if the
ammonia evaporating temperature is dropped from -10f to -15*f
Cause efficiency loss and potential damage to the suction line
Damaged insulation on the suction line in an ammonia refrigeration system will?
The temperature at which moisture will condense out of the air
The dew point is?
An indication of the sensible heat content of the air
The dry bulb temperature is?
An increase in the infiltration load on a refrigeration system
A high relative humidity will cause?
Requires more evaporative condenser capacity if it is relatively high
Wet bulb temperature?
Is heavier than warm air
Cold air?
Air that has zero moisture content
Dry air?
The air has less ability to absorb moisture
Higher wet bulb temperatures reduce evaporative condenser capacity because?
The total heat content of the dry air and the moisture in the air
On a psychrometric chart, enthalpy is used to describe?
Absolute water content stays fixed even if the temperature of the air changes
The difference between absolute water content in air and relative humidity is?
The dry bulb, wet bulb, and dew point temperatures are the same
At 100% relative humidity?
The wet bulb temperature will increase
At a given dry bulb temperature, if the relative humidity increases?
Reduced absolute humidity in the room and higher operating costs
Reducing the evaporating temperature of an air unit from 45f to 28f will cause
The total internal heat energy content of a system plus the product of its volume
multiplied by its pressure
Enthalpy is?
Illustrates the change of condition and heat content of a pound of refrigerant at
different points of the refrigeration cycle
The mollier diagram?
Subcooled liquid, a mixture of saturated liquid and vapor, saturated vapor.
The mollier diagram has three regions of refrigerant conditions which are?
, Psia
The pressure scale on an enthalpy diagram typically used in the U.S. is expressed
in?
The heat quantity in a pound of saturated vapor is greater than the heat quantity
in a pound of saturated liquid at the same pressure
In a refrigeration system (at normal refrigeration pressures), how does the heat
content of a pound of saturated vapor compare to the heat content of a pound of
saturated liquid
The refrigerant has rejected the latent heat of condensation and is a saturated
liquid
Moving across the mollier diagram from right to left, what has occurred when the
refrigerant reaches the line in the left side of the mixed liquid and vapor region?
Horizontal because change of state of a refrigerant at constant pressure is done
at a constant temperature.
The temperature lines within the saturated mixture some of an enthalpy diagram
are?
Is saturated liquid
The boundary line between the subcooled liquid region and the saturated mixture
region?
Is saturated vapor
The boundary line that separates the saturated mixture region and the
superheated vapor region?
Heat of compression
A simple refrigeration cycle plotted on the enthalpy diagram illustrates why a
condenser must reject more heat Than just the heat absorbed in the evaporator
because of?
Does not change
A vertical change (change of pressure) in the subcooled liquid region or in the
saturated mixture region ______________ the enthalpy of the refrigerant at that
point
The evaporator (DX), suction lines, compressors
Superheat enters the system at?
There is less flash gas formed for the low stage compressor to handle
In a two-stage system, subcooled liquid entering the evaporator generally
enhances the performance of the system because?
The new suction line on the roof was not insulated, and the condensers are
sealed
As the operator of a refrigeration plant, the owner indicates that the power
consumption (kwh) is up 15% over this time last year. The owner wants to know
why there is such a huge increase in consumption. The cause is?
