When it comes operating temperatures. I’m running my chiller at -40c and my recovery vessel at 43c. I would prefer to operate recovery at 29.4 for efficiency and speed. Condensing takes longer than evaporation so 43c seems like it would waste butane vapor bc it’s in a vapor form longer at higher temps and pressures being more. So it slow down overall operation. Am I misunderstanding this?
Are you recovering active or passive?
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Oeff
With out the answer to @Dred_pirate
I am asuming you run passive
43 C great but at what pressure in the vessel with valves closed for 3 minutes ?
Heating fluid temperature is not the butane liquid temperature in general
I can run at 70 C but my equilibrium for 70% of solvent recovery is 27 C
Pressure is directly correlated to temperature with singel solvents reason I ask
Chiller is set at -40 but does it hold that temperature treu out recovery ?
If it does great butane condenses at -1C
So the kw of the chiller will decide you potential recovery speeds
The warmer the vapors of recovery the
Less cold they need to condense
So sometimes it makes sense to restrict the vapor path a bit to rise temp and pressure and recover at a faster pace than without the restriction
If the chiller has sufficient cooling power
It s possible that your condensing area is to small/short enlarging the coil or condensor can help
Ps the better the vacuum pulled on a vessel system the beter the speed if you are able to condense fast
The pressure differential between vessels is highest with good v acuut pulled prior to recovery
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It’s not quite that simple.
Vapor temperature correlates with pressure, at higher pressures, less heat (enthalpy) removal is required to condense butane into a liquid state.
Considering that the phase transformation is the most energy intensive part of the loop, this is a good thing.
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You’re correct in thinking that running your recovery vessel at 43°C may not be the most efficient. While higher temps speed up evaporation, they also increase vapor pressure and volume, which can overwhelm your condenser and slow down overall recovery. This can lead to longer recovery times and potential vapor loss, especially if your chiller or recovery coil can’t keep up.
Running your recovery vessel closer to 29.4°C (85°F) is typically more efficient overall. It slightly slows evaporation but drastically improves condensation by keeping vapor pressure lower and more manageable. This leads to a smoother, faster recovery cycle with less wasted solvent and reduced system strain.
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This is pretty hard to generalize though.
It really depends on overall condenser design. It is a fact that as pressure and temp are increased, the enthalpy required for condensing is less.
So if you input the same kW of heat but reduce the overall enthalpy of condensation, less kW are required to condense overall. The issue you raise occurs primarily when the geometry of the condenser is a limiting factor
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You do realize that a higher pressure gas takes less cooling to condense it right? This is why a refrigerator can operate on 110° days without a chiller it just has a big condenser coil on the back of the refrigerator and runs at a pressure high enough that it condenses at 120-150 Fahrenheit.
There’s physically less enthalpy requirements to fully condense a higher pressure gas than a lower pressure gas. Which is the same to say that it takes less enthalpy to boil a higher pressure gas than a lower pressure one.
Simply raising your basin pressure means you need less heat to boil more gas per minute.
Just as simply raising your condenser pressure needs less cooling capacity to condense more gas per minute. 
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