Unit 21 Quiz

The difference in temperature between the boiling refrigerant temperature and the evaporator outlet temperature is known as __________.

• suction line superheat

• temperature difference

• delta T

• evaporator superheat

A low evaporator superheat indicates

• undercharge.

• system restriction.

• overcharge.

• dirt buildup.

When an evaporator experiences a heat-load increase, the suction pressure

• remains constant.

• decreases.

• varies up and down.

• increases.

When the evaporator removes heat from the air and lowers the temperature of the air, ________.

• refrigerant vapor condenses to liquid

• moisture is added to the air

• sensible heat is removed from the air

• latent heat is added to the air

A medium-temperature refrigeration box operates within what temperature range?

• 28°F to 40°F

• 40°F to 60°F

• 0°F to 220°F

• 0°F to 50°F

When moisture is removed from the air, latent heat is removed.

• True

• False

Natural-convection evaporators use a blower to force or induce air over the coil to improve the efficiency of the heat exchange.

• True

• False

When a refrigerated space has been allowed to warm up considerably, the system must _______.

• a. be defrosted at regular intervals

• b. go through a hot pulldown

• c. be overcharged to remove the excess heat

• d. turned off and the product being cooled moved to another cooler

Flooding the compressor crankcase with liquid refrigerant can cause _______.

• a. oil foaming

• b. moisture to accumulate in the compressor oil

• c. excessive superheat

• d. a starved evaporator

Two common methods for defrosting a low temperature evaporator are ________.

• a. hot gas and electric heat

• b. off-cycle and hot gas

• c. reverse cycle and hot gas

• d. off-cycle and electric heat