Unit 21 Evaporators and the refrigeration system

What is the function of the evaporator

The evaporator, absorbs heat into the refrigeration system

efrigerant in the evaporator changes from

Refrigerant in the evaporator changes from a liquid to vapor

The heat that is added to a vapor after all the liquid has boild away is referred to as

superheat

What determines the pressure on the low side of the system ?

The metering device

What is typical superheat for a evaporator

8 to 12F of superheat

What does a High superheat indicate

A starved evaporator

A low evaporator superheat indicates

A low evaporator superheat indicated system restriction

Why are multi circuit evaporators used?

Multicircuit evaporators keep excessive pressure drop from occurring in the evaporator

What type of expansion devices do flooded evaporators use?

Use a float metering device to keep the liquid level as high as possible in the evaporator

Dry-type evaporators are also called

Dry-type evaporators are also called direct-expansion evaporators

What happens when an evaporator experiences a heat load increase?

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

What is used for low temp. defrost ?

Hot gas defrost or electrical heaters

A mediume temp. refrigerator box operates at which temperatures ?

28 to 40F or 32 to 45

WHat are 7 advantages that a aluminume ,parallel flow, plate/fin evaporator has over a standard round copper tube plate fin evaporator?

Advantages of Aluminum parallel flow, plate/fin evaporator are:
Reduce static pressure thru the coil-which means fewer fan watts and less horsepower. - Reduces coil depth for the evaporator and condenser, which leads to easier cleaning an less air side st

list different types of evaporators

forced draft, stamped evaporator, multicircuit, finned tube bare pipe, liquid heat exchangers, drum type evaporator, plate type evaporator in a tank, pipe in pipe evaporator