Originally Posted by
Superfridge
RANGER1 i have always looked at this system as two stage but your desription is correct I guess, single stage economised. I will ammend.
The economiser is open, no subcooler.
HP liquid from HP reciver enters IP pot, flash gas goes to comp economiser port, IP liquid enters LP separator, LP liquid is pumped to evaps.
I have closed down ecomomiser isolation valve and found comp port pressure to be 200kpa at 100% slide and at design pressures. Comp is on VSD so nearly always at 100% slide. Below 75% economiser BPRV closes/de-energises and economiser flash gas enters suction via BPV set slightly higher than econ BPRV.
Would it be just a matter of setting IP BPRV to say 50kpa or so above maximin compressor economiser port pressure? As long as IP to LP soleniod and hand expansion valves can cope with the low pressure drop and maybe two phase liquid.(not 100% saturated)
I would hope there is a more scientific means than this!
Or stick with geometric mean?
Cheers