superheat help

[Krups]

Hey all, my question is this... what is the procedure necessary to measure the amount of superheat supplied at the sensing phial by the an internally equalised tev ?

does that sound more confusing than it is, or is lack of sleep jus making me dumber ?

my attempted answer is to check the evap temp via gauges against the temp at the phial,noting a diff of approx 6°c (in a frozen food display unit)

[Prof Sporlan]

Hey all, my question is this... what is the procedure necessary to measure the amount of superheat supplied at the sensing phial by the an internally equalised tev ?

It is the same for either an internally or externally equalized TEV, i.e., check pressure at the evaporator outlet, convert to temperature, and determine the difference between this reading and the suction line temperature at the bulb location.

my attempted answer is to check the evap temp via gauges against the temp at the phial,noting a diff of approx 6°c (in a frozen food display unit)

This is correct. Note that if you are have a 400-series refrigerant blend in the system, make sure you convert your pressure reading to dew point temperature

[Krups]

thanks prof, are u really a prof ?
and what is dew point temperature ? and why the conversion to this ? iv never come across that ? unless its also known under another term..

[chemi-cool]

hi krups,

I do it, using two probe thermometer.
one sensor is connected at the TEV outlet - T1

the second, at the outlet of the evaporator - T2

adjust the superheat when system is properly charged.

its basicly the same as the Prof says but you dont always get a schreder valve at the evaporator outlet.

chemi

[Prof Sporlan]

thanks prof, are u really a prof ?

A professor of all things related to Sporlan, absolutely...

and what is dew point temperature ? and why the conversion to this ? iv never come across that ? unless its also known under another term..

Saturated vapor temperature would be another term. At a given pressure saturated vapor and liquid temperatures are identical for a single constituent refrigerant, e.g., R-22 or and azeotrope, e.g., R-502. For zeotropes (refrigerant blends), they are not. You may find the following Sporlan P-T chart of interest: http://www.sporlan.com/form1.htm

hi krups,

I do it, using two probe thermometer.
one sensor is connected at the TEV outlet - T1

the second, at the outlet of the evaporator - T2

The infamous two temperature method of measuring superheat... Not as accurate as the pressure-temperature method, but it is certainly convenient if a pressure tap is unavailable.

[Krups]

thnx people, this has been very useful