Vapour pressure at 20Â°C for R404a is 167.2 PSIG, and for R134a it is 84 PSIG, R1150 5C is 470 PSIG.
The original Mach I/II/II ST models ran with R134a, so the switch from R134a to R404a essentially means that the Prometeia Mach II GT can attain lower evaporator (cold head) temperatures and shorter start-up times. The working pressures inside the Mach II GT unit is 331 PSIG on the high side, 174 PSIG on the low side. The evaporator temperature is -50C unloaded and -35C -40C loaded at normally 200W maximum for one unit. The specs in the Danfoss pdf is for R134A not R404A. R404A gives better temps than the 28.9 C @ 160 in the chart correct?
2 Prommies in parallel;
-200 W X 2 Prommies = 400 Watts @ -35C -40C (total load capacity).
-High pressure would be 662 PSIG and the low 348 PSIG. Approximately 45 bar on the high and 24 bar on the low.
-With the current -50C unloaded or -35C -40C loaded temps there would be enough - temps out of the HX to satisfy the low temp stage for the ethylene R1150.
-Assuming a Delta of -5C, possibly -40C -45C (added -35 and -40C from above respectively to the -5C) @ 260W requirement (i7 920 loaded).
-According to the watt chart a load of 260W would be -20C. Referring to the P/T chart @ -20C R1150 ethylene is equal to 30 bar or 435.1PSIG . Our high pressure is 662 PSIG, heat rejection processes by condensation can be established through the condenser as we're still within the bounds of the critical point. Even -12C @ 400 Watts in the Danfoss chart, referring to the P/T chart it would be 35 bar or 507.6 PSIG.
or not, that is the question I ask of thee.
P/T Chart for R1150 Ethylene
Edited by acdcmike - 2/5/10 at 7:06am