Capillary tube and TEV

[NoJosh]

Which is the most reliable when thinking about great temp/pressure difference between high side and low side for eksample evap: 15 degc condens: 55degc?

[Rob White]

.

Its not that simple :D

Capillary tubes are basic, they have no moving parts and
are very cheap. Cap tubes have their place but there is
no control over a cap tube. it gives a prescribed pressure
drop over its length. If you require more then you need
something that can be controlled or adjusted and that is
where the Thermostatic Expansion Valves (TEV), Electronic
Expansion Valves (EEV) came into play.

TEV's are fairly bullet proof and do their job well but because
of a mechanical delay inside the valve they need a wide-ish
superheat to be able to control safely so that means a %
of the evaporator is not used for heat exchange (it is only used
to superheat the refrigerant vapour).

EEV's have much more control so they can have less fluctuations
regarding the amount of liquid in the evaporator at any time.

Horses for courses is what we say :D

The application dictates the choice and there are hundreds
of considerations to take into account.

The biggest consideration is cost.........

Regards

Rob

.

[NoJosh]

Thank you for your reply :)

[NoJosh]

I was wondering, if the capillary tube gives a prescribed pressure drop, what would happen if the ambient or the room temperature changes. And what if ambient temperature stays constand and only room temperature changes. If for eksample the ambient is 55c and room is 30c, and the room temperature falls to 25c but ambient stays 55c.

[WootAC??]

I have a question too about this subject, what if you have an ambient of 55 celsius, a condensing temp of 60 cesius and a evaporator temp on 20 celsius, what will happen if a capillary tube is used and the ambient drops to ex. 20 celcius, what will happen?
I'm wondering about how this will affect the system and if the condensing and evaporating temperatures will change?

Regards

Michell