High and low pressure for a Bottel Cooler

[arzuamir]

Sir, I have to replace a Compressor Tecumseh model AEA4440YXD,R-134a,In a bottel cooler oprating tempreture are 2 - 8 centig.With Danffos Compressor Model:FR10G,R-134a.
my question is what Back Pressure and high Pressure will be in a Bottel cooler when Condensor and avaporator bothe are fins type and both are fixed with a fan.
Please reply soon. thanks

[install monkey]

what pressures are u getting and did u change the drier and vac the system,was the refrigerant weighed in?

[nike123]

That Danfoss compressor is not correct replacement for Tecumseh AEA4440YXD.
You need compressor closer to 12 cm^3/revolution displacement and that Danfoss has only 9,05 cm^3/revolution.
You could use Danfoss FR11G which is 11,15 cm^3/revolution or better SC12G with 12,85 cm^3/revolution.

Condenser TD should be 10-20K.
Evaporator TD should be around 10K.

Evaporator TD=Tai-Te
Condenser TD=Tc-Tai

TD=Temperature Difference
Tai =Temperature Air In
Te=Temperature Evaporation
Tc=Temperature Condensation

Pressures are found by calculating these temperature intervals and finding corresponding saturation temperature/pressures for refrigerant in use.

[arzuamir]

what pressures are u getting and did u change the drier and vac the system,was the refrigerant weighed in?
20Psi low Pressure and 100Psi,Temp after 45 Minut Run 13 Centig.Yes I changed the filter drier(filled with Silica gel),Vac the system by a 5cf Vaccum pump,But sorry to say we are using suction pressure or temperature as the basis for charging.

[arzuamir]

Dear engineers,
I am sorry to say that no body wants to answer a simple quistion. My simple quistion was that what suction pressure& discharge pressure will be in a bottel cooler when its charged with R-134a, as we knows suction Pressure 25-35psi & discharge pressure 160-180 psi is for the bottel cooler when R-12 is charged. same like this i want to know what suction and discharge pressure should be in a bottel cooler when its charged with R-134a.if I know the figure

[nike123]

We are trying to teach you how to fish, and you still want fish served on plate.:mad:
I call that "feeder".

Once again:

Condenser TD should be 10-20K.
Evaporator TD should be around 10K.

Evaporator TD=Tai-Te
Condenser TD=Tc-Tai

TD=Temperature Difference
Tai =Temperature Air In
Te=Temperature Evaporation
Tc=Temperature Condensation

Pressures are found by calculating these temperature intervals and finding corresponding saturation temperature/pressures for refrigerant in use

[arzuamir]

We are trying to teach you how to fish, and you still want fish served on plate.:mad:
I call that "feeder".

Once again:
Dear Mr. Nike123.I appreciate u for quick respond.my problem is that i am working a place without thermometer. with a vaccum pump and a manifold gauge only.so if i get the any idea about pressure i can adjest the cappilary size to get the required tempreture.any way thanks a lot.

[nike123]

You cannot do this job without thermometer!
Pressure depend on temperature (and humidity) of air and if you don't know temperature (DB and WB) you cannot know what pressure should be.

[nike123]

If your bottle cooler have WB temperature inside of 2°C then Te would be Te= Tai-TD=2°C-10K=-8°C
If ambient air where bottle cooler is placed is 30°C then Tc would be Tc=Tai+TD= 30°C + 10-20K=40°C to 50°C depending on type and size of condenser.

That converted in saturation pressures of R134a is
Pe=1,17barg=17PSIg
Pc=9barg to 12barg=130 to 175PSIg

Change temperatures and all is changing.

[npendlebury]

20 to 25 psi gives you evaporating temperature sufficently below the set point of the cooler to give you descent superheat without flooding or starving the evap, 125 to 150 psi head would be around right if your ambient is 25 to 30 C or a bit higher even if conditions are onerous, 134a is as near to R12 that it makes no difference just the high pressure is a little more. take no notice of Brainiac because he is obviously so full off **** its pouring out of his moth all over the key board, hope that helps