froudeg
10-11-2004, 05:47 AM
Hi,
Im in the process of building my cascade setup, and am unsure of the cap tube length on the first stage. I'm targetting a 500watt heat load capacity on the first stage - for the single stage setup's i've built, i followed gary's rule of thumb for cap tube lengths on R404A (10 foot, for 150 watts...loose a foot for every 15 watts from there.
Obviously this rule of thumb wont work for large heat loads - so, from the guy's who have experience with cascades - whats your rule of thumb for large heat loads such as 500 watts? - btw im using 0.026" cap tube, i know that if you used 0.028" i just need to shorten it somewhat (30% seems general rule).
I've got some TEV's here, that i was planning to use - but their capacity range is from 500 watts upwards - which is no good if im wanting it to work within a 200-600 watt sorta range....altho i did have an idea of using this along with cap tube, to effectively lower the minimum capacity it can adjust within.
By the way, the second stage is ethane with a target 200 watt heat load and not ethylene etc - ie it only needs a -20c condensing temperature, which means i dont need massive 1/2hp compressors on 1st stage, and dont need anything more than a 500 watt capacity on the first stage - should be more than enuf.
Any help is appreciated.
Im in the process of building my cascade setup, and am unsure of the cap tube length on the first stage. I'm targetting a 500watt heat load capacity on the first stage - for the single stage setup's i've built, i followed gary's rule of thumb for cap tube lengths on R404A (10 foot, for 150 watts...loose a foot for every 15 watts from there.
Obviously this rule of thumb wont work for large heat loads - so, from the guy's who have experience with cascades - whats your rule of thumb for large heat loads such as 500 watts? - btw im using 0.026" cap tube, i know that if you used 0.028" i just need to shorten it somewhat (30% seems general rule).
I've got some TEV's here, that i was planning to use - but their capacity range is from 500 watts upwards - which is no good if im wanting it to work within a 200-600 watt sorta range....altho i did have an idea of using this along with cap tube, to effectively lower the minimum capacity it can adjust within.
By the way, the second stage is ethane with a target 200 watt heat load and not ethylene etc - ie it only needs a -20c condensing temperature, which means i dont need massive 1/2hp compressors on 1st stage, and dont need anything more than a 500 watt capacity on the first stage - should be more than enuf.
Any help is appreciated.