3stage idea

[tim-]

Hi,
was thinking about some 3stage ideas, this is my final idea.

http://www.phasechange.se/photos/misc/3stageidea.jpg

as the blueprint shows, thinking of using desuperheater on second and thirdstage (aircooled) and then use first stage as a second desuperheater on thirdstage. Was thinking about it since the gas is hot, and the more cooled the gas is before hitting ~-90*c hx the bigger capacity.

what do you think about this idea?

regards
tim

[n00b 0f l337]

Will help you but having the second evaporator might not be as good as an SLHX and a shorter captube on the first.

[jinu117]

One on left most side can be taken out. Other than that, I don't see problem with it.
There seems to be some misunderstanding about SLHX (or economizer).
It would be better to do without one if possible due to just additional cost.
If someone has been playing with multi stage cascade, they should know that efficiency goes down drastically as you go further in stages. So instead of using lower efficient part of system, we use higher EER system to "boost" up the lower EER part of system. Hence the term economizer. The way I see it being used in SS sometimes are kind of funny. It's actually doing something else other than what lot of people has been lead to believe if someone starts digging further into it...

[tim-]

I try to avoid the slhx due to the huge superheat it cause. I know r507 has no problems with big superheat, but how about r410? I think it's better to go with two evaporators then one + slhx.

jinu:
That's why I was thinking of using two evaporators on first stage since it's the strongest stage and easiest to make bigger, just putting a strong compressor with correct sized condenser.,

was thinking about;
first stage: 24k btu
second stage: 17k btu
third 14k or 12k btu

if precool third stage gas before hitting second hx i can gain in capacity on last evaporator as well. Instead of cooling ~25*c gas in second cascade hx to -90*c I can put -40*c gas in second cascade hx which means alot of the heat is already removed.. it means the second stage will be able to keep the temp down in 2nd cascade hx with bigger load then without precooled gas.

I think I got it correct, atleast as I have been teached in school :confused:


[edit]
just to make it clear, safety as well as solenoid for pressure equalizing, shutoff valves, relief valves isn't drawn in this scheme. also recivers, accumulator is going to be added.. this is just a basic print to show the idea.


Regards
Tim