confused?????

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19-09-2012, 12:37 AM
stocky07

confused?????

I am new to this site and new to HVAC. I am a student at local communiity college taken HVAC course. I thought I understood material until I got home and drew a blank. I am hoping someone can help me understand how to use certain formulas for calculating. EX.

Given: R-22
evap. outlet superheat = 10 f
evap. outlet temp. = 50 f
cond. pressure = 246.1 psig

Find: evap saturation temp. =
evap pressure =
condensing temp. =
amb.temp. =
if subcooling = 12 f, the cond. outlet temp. =

This is my second day of class. The biggest problem is trying to digest 7hrs of class information. I have to deal with it until Nov; I will never take such a long class again,it's too much but I will succeed. Can someone help me understand this proplem?
19-09-2012, 09:05 AM
desA

Re: confused?????

A few hints

Te,sat (evap sat press)= outlet temp - SH
At Te,sat => find evap saturation pressure
At cond. pressure => Tc,sat (cond sat temp)
Amb. temp = anyone? (Suspect an approach, or TD may be required here - off either evap, or cond?)
Cond outlet temp = Tc,sat - SC
20-09-2012, 11:13 AM
Rob White

Re: confused?????

Quote:

Originally Posted by stocky07

I am new to this site and new to HVAC. I am a student at local communiity college taken HVAC course. I thought I understood material until I got home and drew a blank. I am hoping someone can help me understand how to use certain formulas for calculating. EX.

Given: R-22
evap. outlet superheat = 10 f
evap. outlet temp. = 50 f
cond. pressure = 246.1 psig

Find: evap saturation temp. =
evap pressure =
condensing temp. =
amb.temp. =
if subcooling = 12 f, the cond. outlet temp. =

This is my second day of class. The biggest problem is trying to digest 7hrs of class information. I have to deal with it until Nov; I will never take such a long class again,it's too much but I will succeed. Can someone help me understand this proplem?

You will need a chart, comparitor or even a new phone app to
work out what pressure a refrigerant will be at a given temp
or visa - versa

A clue cond. pressure = 246.1 psig is about 113degf
With that information everything should drop into place.

Regards

Rob

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