Commercial Refrigeration Ch.2
What is considered the "evaporator temperature"? - Answers -The temperature of the
refrigerant inside the evaporator tubing.
How do you calculate evaporator temperature from the suction pressure? - Answers -
Use a pressure/temperature (P/T) chart.
How is evaporator TD calculated for a walk-in cooler? - Answers -Subtract the saturated
suction temperature from the box temperature.
What is "hot pull down"? - Answers -When the evaporator is subject to higher
temperatures and loads than under normal operating conditions.
During hot pull down what is the evaporator experiencing? - Answers -Starving because
the refrigerant is boiling off quickly.
What is the approximate humidity in a walk-in refrigerator with a 10° TD evaporator? -
Answers -85%
As TD increases how does it affect box humidity? - Answers -Decreases humidity.
If airflow across an evaporator is decreased, what effect does it have on evaporator
temperatures and suction pressure? - Answers -Evaporator temperature and suction
pressure both decrease.
Why are multiple circuits used on larger evaporator coils? - Answers -They provides
less pressure drop than a long single circuit evaporator.
If the suction pressure of an R22 unit is 55 psig, what is the approximate evaporator
temperature? - Answers -30°
If the suction pressure of an R404A unit is 21 psig, what is the approximate evaporator
temperature? - Answers --14°
How do you determine the evaporator superheat of a refrigeration system? - Answers -
Subtract evaporator temperature from the temperature of the suction line at the
expansion valve bulb.
A -10° walk-in freezer using R404A has a suction pressure of 15 psig. The suction line
temperature at the TEV bulb is -20. What is the evaporator superheat? - Answers -2°
