Low Load Limits

Both liquid distributors and TEV’s have low load Limitations

Over sizing of devices will cause unequal distribution of refrigerant through the evaporator circuits at low loads

The top of the evaporator circuits will begin to starve

The bottom feeder will cause flooding to the compressor

If this situation is found the size of the nozzle can be changes to smaller size

The low load limits for most nozzles is about 50% of its capacity

The low load limits for the TEV is 30% of its rated maximum cap.

 

 A TEV that is operating below its low load limit will cause HUNTING and it can be detected by:

Taking a temperature measurement at the bulb and recording superheat readings for a certain amount of time

Reading will be erratic and not constant

 

Double- Ported Expansion Valve

This type of TEV allows connection of two separate evaporator circuits without the use of a distribution device

 

Liquid Distributors

In order to provide equal refrigerant distribution through an evaporator with more than one circuit a liquid distributor is used

Can have 2 to 40 lines depending on the size of the evaporator

Always uses an externally equalized line because of pressure drop

There is only one distributor per metering device

Some liquid distributors use a thick flat washer inside the distributor (called a nozzle)

It provides for pressure drop

Better mixture of the liquid and gas

Ensures equal mixture of the liquid and gas detection to all circuits

They are inter changeable