Calculate Minimum L oa d
To calculate minimum load conditions, estimat e the temperature di ff er e nce that the cooler
will have at 20% load, the n es t imate what the suction an d condensing tempe r at ures will be at
this point. Use the prope r saturated pressure an d temperature for the particular refrige r ant
used.
Suction Temperat ure:
43 F (6.1 C) = 38 psig (262 kPa) saturated refrigerant pressure (HFC-134a)
Condensing Temp erature:
70 F (21.1 C) = 71 psig (490 kPa) s at urated refrigerant pressure (HFC-134a)
Minimum Load ∆T1 ( at 20% Load):
2° F (1.1° C)
Minimum Load ∆P1:
71 – 38 = 33 psid (490 – 262 = 228 kPad)
Again, to avoid unnece s s ar y s ur ge prevention, add 20 psid (140 kPad) at ∆P1 from these
conditions:
∆T1 = 2° F (1.1° C)
∆P1 = 53 psid ( 368 kPad)