AKV Subcooling. Why?

[Peter_1]

Apart from the bigger capacity the AKV will give due to higher SC rates, what's the reason behind this necessity?
Is it to be sure you don't have flash-gas or is there another reason?
Will the valve behave technical otherwise or encounter technical difficulties when running with lower SC rates or no SC at all?

[RANGER1]

Peter_1,
The only information Danfoss give reference that I can find is to ensure you don't have
flash gas.
Technical litrature says standard 4K SC is OK,after more than 4K correction factor is used to determine valve capacity.
Maybe you have seen something else?

[mad fridgie]

Think of your EEV or any expansion device as a compressor in reverse. They are both effectively volume devices.
It is then the density and pressure difference will give a mass flow,
The EEV (AKV) will have a control PID, that takes into account a relatively fixed density of the liquid feed, by having low sub cooling, you introduce the chance of flash gas, effectivelly reducing the mass flow through the valve and makeing it difficult for the valve electronics to tune the system, and loosing some of the benefits (plus you could also "draw" (scratch) the valve seat

[Aik]

There are no special technical difficulties, only protection on flash gas such as TEV. Danfoss recommend that velocity on liquid tube not exceed 1 m/s. About high sub cooling, you know without me that big sub cooling bring more capacity...
We use AKV with controller EKC 414A1 on many vegetable/fruit stores (without solenoids)...sub cooling never measure

[Magoo]

Abreviations really get up my nose.

[mikeref]

Abreviations really get up my nose.
Reading this thread also had me with a question mark hovering over my head?.. thanks Mad, AKV is EEV but what is (control PID?):rolleyes:, Person In Distress:confused:?? LMAO, Magoo:D.. Mike.

[mad fridgie]

Reading this thread also had me with a question mark hovering over my head?.. thanks Mad, AKV is EEV but what is (control PID?):rolleyes:, Person In Distress:confused:?? LMAO, Magoo:D.. Mike.
And you want me to have ago at spelling it, be on your head
PID = proportional–integral–derivative
I cheated lol!

[mikeref]

Struth!! That really made it as clear as mud.:eek:. PID will have to do.

[mad fridgie]

"PID" clear as mud, thats about right, it is just a set of calculations that is used to control a modulating device.
In true terms, it is all about the error from set point (what is the difference between the set point and the actual reading)
This part of the explanation is not quite true but will let understand better.
Think of a standard coldroom controlled a normal on/off thermostat, you want an average temp of 4C, what do you set the stat to, you need a cut in temp and cut out temp. "stat set point and differential" so we would have set point of 6C and a diff of 4C (cut out 2C). If we had a inverter compressor, then this would be a pretty shyty control. What would control the inverter, not the normal thermostat, some fancy electronics, with PID control, basically the PID control changes the spped of the compressor to attempt to maintain set point, the warmer the actual temperature, the faster the compressor (P) "present", how long it has taken to change the actual temp (I)"past" and how long does it thinks it will take to change the temperature "D" (future).
Still clear as mud, of course. advice press "auto tune" button, and the let clever bugger who wrote program work out how to best run the device

[Magoo]

Hi MAD
PID. aka "Price includes discount". What about Poets day, have you come across that.

[Magoo]

Back to the original Post, sub cooling below nominal, increases the TXV performance. Nominal 2 degrees = 1 % increase, plus the liquid line sizing can be smaller . Less flashing in liquid line befroe TXV . As a rule I always install a sight glass in liquid line before the TXV. Plus schrader valves everywhere. Saves all the guess work.

PS, MF . POETS day is Friday