DISCHARGE TEMP ON AIR COOLED RECIPROCATING CHILLER 1

[justincase]

Hi guys---

What would be considered an excessive discharge temperature on an air cooled reciprocating chiller?

Thanks for your time.

 

[gepman]

Some reciprocating compressors rely only on natural convection to cool the heads while others may have may have a forced air fan on top of the heads for cooling (others have water-cooled heads but you stated air-cooled). The maximum allowable discharge temperature will depend on the type of cooling your compressor has and somewhat on the design of the compressor. Usually the compressor manufacturer will give you this information. What make and model is your compressor?

 

[MintJulep]

I would consider 958 C excessive.

 

[justincase]

gepman--- I wish I knew exactly what "compressor" my mentor was referring to.

I'm taking a test with 120 questions and only got about 25 of them right.

I've only just completed a 6 month training in the basics of
HVAC/R and we did not go over anything in depth relating to the "Big Stuff" such as centrifugal chillers, cooling towers, boilers, and basically any thing over 5 tons.

The job I'm currently interviewing with looks like they are going to hire me and give me the training to work on the larger equipment.

The lead tech I'm going to be training under told me to go out and find as many answers as I could by any means.

I've been surfing the net, going to the library and making phone calls. It seems to me that a lot of this information
I'm seeking is stored away in company manuals that cost major $$$. So I will keep searching.

@ MintJulep--- I think you are right-- 958 C would be toasty.

 

[gepman]

I think that MintJulep meant 95.8 C. I copied the following out of a Carlyle compressor book:

R-22 applications require an oil cooler when (absolute)
pressure ratio is greater than 5.0; oil cooler and
water-cooled heads required when discharge temperature
is greater than 250 F.
R-134a applications require an oil cooler and watercooled
heads when the discharge temperature is
greater than 275 F.
R-507/404A applications require an oil cooler when
the SST is less than –20 F and require an oil cooler
and water-cooled heads when the discharge temperature
is greater than 275 F.

Good luck with the job. By the way you can get a lot of the manuals on the web.

It will vary somewhat on the compressor.

 

[MintJulep]

Naw, I was just being a wiseass.

With no details about the compressor or application, there really is no way to answer the question.

 

[Yorkman]

Gepman is right on target, what your concerned with is the temperature of the oil, most mineral oils start to burn/breakdown at 300-350 degrees F. Synthetic oils which is what you will see in R-134a and most 400 series blends don't actually break down at these temperatures but loose their lubricity. Actually boiling or flashing off the cylinder walls.

Generally if you take the discharge temperature and add 75 degrees that is the aprox. temperature of the vapor/oil at the discharge valves.

I'm not a real engineer, but I play one on T.V.
A.J. Gest, York Int./JCI

 

[justincase]

Thanks for your time guys--

I think a copy of this thread stapled to the question
should work as a acceptable answer.

One thing I've noticed is that a question without spec's is very hard to answer indeed.

@MintJulep---LOL, I kinda thought you was test'n me

 

[imok2]

The limit to any compressor discharge temperature is 225 degrees F. If the discharge temperature gets higher than 225 degrees, the system may start to fail from worn rings, acid formations, and oil breakdown. Remember, if the discharge temperature is 225 degrees, the actual discharge valve will be about 75 degrees hotter. This will bring the actual compressor’s discharge valve to 300 degrees. It is a known fact that most oil may start to break down and vaporize at 350 degrees. If this occurs, serious overheating problems will happen. And, since compressor overheating problems are today’s most serious compressor field problems, the service technician must always monitor compressor discharge temperatures and keep them under 225 degrees.

 

[yorkmangr]

Justincase following your question i have to tel u the following
Your end compression temperature is following your suction superheat
when u working with a very high suction superheat,your oil it will get hot and that it will effect your end compression temperature,so try to keep your suction superheat as low possible,in that way u be able to cool your oil and keep your end compression temperature with in normal condition
YORK reciprocation chillers with R22 working from 75C-95C

 

[andy290]

I just replaced my intermittent pilot ignition with a honeywell s8610u and i am having a problem and cxould use some help. When it tryes to start the pilot lights for about 15 sec and then go out it does this about 3or 4 times then waites for about 5 min then retries it then lights the burner it is giving me a 6-2 code any idears? thanks