Calculating SCT

any one know of or have the formula for calculating
Saturated Condenser Temperature calculated from Condenser Discharge Pressure. It requires some additional analog inputs
but that not a problem.Just need to find a calculation I can use in a CLK PLC

Hello,
Sorry I don't have the answer to your question, but I am a bit curious as to what refrigerant you are using.

Here in the states (and elsewhere I am sure) all of the pure refrigerants are going by the wayside, so if you are not using Ammonia, then it may be very difficult to get a steady/accurate calculation of this, due to the fact that most of the newer blend refrigerants have a Glide a Mile Wide.

BCS

Ammonia

It is ammonia and glycol

Glide is the enemy!

If no refrigeration experts pop up here, I would try my luck over on this specific Forum...

Refrigeration-Engineering.com

Regards,
George

@asterof..... At least you are working with something somewhat stable and predictable.
(We are doing a total retro from R-22 to Ammonia at the end of this season also)

I gotta run for the night but if you don't find anything I will poke around and maybe make a couple calls and see if I can find something for you tomorrow.

The only thing that comes to my mind at the moment would be a look-up table done in Excel or something similar using Ammonias P/T Chart.
(but I know this is not what you are looking for)

@Geospark.....See what you did, now I have another forum to lurk around in. Never going to get any work done.

Seriously though that looks like a very interesting site. I will check it out some more tomorrow. Thanks for posting that.

(I have a refrigeration background and license as well as electrical so that site is a nice find for me)

BCS

Well as far as a Pre-rolled calculation you can use in a PLC for Saturated Condenser Temp for Ammonia I have not found anything.
I made a call to a friend that is big in larger refrigeration systems and he said the same thing I did. "Just use the P/T chart"

Anyway I am still not sure why you want to calculate this in the PLC, but I am curious though. (See your other thread)

Here is the P/T chart, you can see that Ammonia is pretty darn close to linear in certain Pressure / Temp ranges but is not quite there and does not stay that way for a very long span.


http://www.engineeringtoolbox.com/ammonia-pressure-temperature-d_361.html


So if you REALLY need this you will have a lot of scaling parameters or will need to find someway to represent this chart in the PLC by only using the pressure exiting the Condenser.
(I am not sure how you will do that but there are some really smart people here and maybe one of them will give you an idea)

Edit: here is some further info on Ammonia properties if anyone is interested.

http://www.engineeringtoolbox.com/ammonia-d_971.html


BCS

Is this what you are looking for?

http://profmaster.blogspot.com/2009/08/ammonia-vapor-pressure-temperature.html

boneless said:

Is this what you are looking for?

http://profmaster.blogspot.com/2009/08/ammonia-vapor-pressure-temperature.html

Click to expand...

WOW, that looks easy.
I cant wait to see what the OP says.

EDIT: also if you read down another Egghead wrote this in the comments, but there was no reply posted.

Anonymous said...
The equation for calculating temperature, when pressure is known is incorrect. The equation for calculating pressure is working correctly though. Please explain, as I need to program this into my electronic expansion valve.

Click to expand...

BCS

Not sure, it might be a user mistake

The temperature is in Kelvin, maybe he was expecting Celsius?

Good find on that though, it is more than I found on any refrigeration site, never thought to look under Chemical Engineering.

All I can say is, "I am glad that anything I need to do can be done off the P/T chart".

All the rest of that is way above my pay grade.


BCS

aren't you paid in shares?

boneless said:

aren't you paid in shares?

Click to expand...

Yes and quite well if I do say so myself.

(But we are going to get in trouble for hijacking this tread to BS)

Have a good one and see you around town.

BCS

Yes i do have the calcs look at www.oscat.de
what is the stuff, water, ammonia, glycol etc.