Refrigerant Properties

[stephen.t]

Hi there!

Please could somebody clarify how a refrigerant's boiling point (at 1 Atm) is correlated to the lowest achievable temperature of the system ?

e.g.
for R600a, which has a boiling point of -11.6 C, what's the lowest air temperature that could be achieved ?

Similarly, for R290, which has a boiling point of -42.1 C, what's the lowest air temperature that could be achieved ?

Many Thanks in advance...

[Josip]

Hi there!

Please could somebody clarify how a refrigerant's boiling point (at 1 Atm) is correlated to the lowest achievable temperature of the system ?

e.g.
for R600a, which has a boiling point of -11.6 C, what's the lowest air temperature that could be achieved ?

Similarly, for R290, which has a boiling point of -42.1 C, what's the lowest air temperature that could be achieved ?

Many Thanks in advance...

Simple...refrigeration system is a closed system and we use regulating - expansion valve and compressor to reduce internal pressure, thus our refrigerant evaporate at lower pressure with lower temperature....

at 0,291 bar (absolute) R600a has a temperature of approximately -39,94*C...the lowest one can be about -46*C....

at 0,702 bar (absolute) R290 has a temperature of approximately -49,9*C....the lowest one can be about -56*C

;), may I ask what for you need low temperature, please

Best regards, Josip :)

[US Iceman]

Please could somebody clarify how a refrigerant's boiling point (at 1 Atm) is correlated to the lowest achievable temperature of the system ?


This questions gets to the heart of the matter for selecting refrigerants at low temperatures. If the saturation (boiling) temperature you need is below the corresponding atmospheric pressure, the system will operate in a vacuum on the low side.

Therefore, if you want to have positive pressure in the evaporator at low temperatures then you need to select a refrigerant which exhibits this characteristic.

Otherwise, if you operate the system in a vacuum you can still get colder temperatures.

[stephen.t]

Thanks Josip & US Iceman

Your answers make things much more clear now..:)

[Yusuf Ismail]

what is your s. pressure ?