R407C Bubble / Dew Temperatures

[ice_cold]

What are the terms dew temperature and bubble temperature for R407C? Regardingly i found some info on them but i can't define which one to use when doing calculations on a system with R407C.

Thanks in advance!

[Toosh]

What are the terms dew temperature and bubble temperature for R407C? Regardingly i found some info on them but i can't define which one to use when doing calculations on a system with R407C.

Thanks in advance!

Hi ice, this makes good reading

http://www.centrogalileo.it/nuovaPA/Articoli%20tecnici/INGLESE%20CONVEGNO/XI%20Convegno%20English/1%20SESSIONE/Morley%20DUPONT%20Ing.pdf

Norm

[taz24]

What are the terms dew temperature and bubble temperature for R407C? Regardingly i found some info on them but i can't define which one to use when doing calculations on a system with R407C.

Thanks in advance!


Think bubble as the point that water bubbles just as it starts to boil or evaporates.

Think of dew as the point where the liquid starts to drop out of the vapour.

So R407 with a glide of 6K means that as the refrigerant starts to boil or evaporate it goes through the bubble point (wet) as it evaporates it glides through the 6K range untill all the liquid has evaporated at the dew point (dry).

Condensing is reversed, as the refrigerant cools to the saturation temp the liquid starts to drop out of the vapour (dew point) then is condenses through the 6K range untill all the vapour has condensed to liquid (bubble point).

All the best taz.

.

[ice_cold]

toosh, great document. it gets into detail i liked it!
and taz thank you. that's well said, so understandable for a beginner like me.

[airmechanix]

Does anyone have an actual P/T chart that reflects the bubble and dew points? how do you account for temperature glide when determining a good condensing temperature?

[nike123]

Dew and bubble point is used only for calculation of superheat and subcooling.
For determining condensation and evaporation saturation temperatures and calculation of aproach and TD you should use mean temperature. There are so many tables around. Google it.

[jowel]

Im just new here in RE, and i have some questions regarding R407C and i hope someone could help me.

We are experiencing some problem with our 10-ton split type air-conditioning unit serving electrical room. The condenser is located near a furnace and the surrounding temperature around the condensing unit is around 45 to 55 degrees celsius. With the refrigerant R407C, the discharge pressure of the compressor is reaching 26 bars and the unit is tripping on a high pressure cut-off. We are located here in Doha, Qatar, what will be the gain if we switch from R407C to R134A? Will it help? Does using R407C refrigerant on such high ambient temperature has something to do with the tripping?

[nike123]

Im just new here in RE, and i have some questions regarding R407C and i hope someone could help me.

We are experiencing some problem with our 10-ton split type air-conditioning unit serving electrical room. The condenser is located near a furnace and the surrounding temperature around the condensing unit is around 45 to 55 degrees celsius. With the refrigerant R407C, the discharge pressure of the compressor is reaching 26 bars and the unit is tripping on a high pressure cut-off. We are located here in Doha, Qatar, what will be the gain if we switch from R407C to R134A? Will it help? Does using R407C refrigerant on such high ambient temperature has something to do with the tripping?

26 bars is 61°C mean temperature and if your ambient goes to 55°C when it trips, than that mean your condenser TD is about 6K which is OK.
Could you relocate condenser unit away from furnace or bring air from colder environment? I suppose that max 50°C would not trip HP switch.