The face velocity of a coil is an indication of the air volume in the system.
The face velocity is a factor that determines the loading on the coil. Depending on the construction of the coil, ie rows, fin count, fin type and construction, refrigerant type, metering device, distributor style...
Static heat pumps work as heat DIODES, IE pump in one direction heat in bottom heat out top.
However, dynamic systems can use refrigerant pumps.
There are also glycol run around systems that may do the trick.
There are static self pumping arrangements that can move heat down, a very simple...
The flowrater is a fixed metering device. It is designed to drop the pressure from design head pressure to design suction pressure. If you install a TX valve in series with it. You have two devices in series that were both designed to drop pressure.
If you can remove the flowrater orifice, the...
""1. Hmm. I see what you are saying. At 0°F my suction pressure is half what it is at 31°F, and thus the evaporator Q is about half.""
No actually, the COMPRESSOR capacity will be half at the lower SST, the evaporator capacity increases with the lower temperature.
""I tried 20F for the...
Food for though
1)For every two degrees drop in SST (saturated suction Temperature) capacity drops required power increases.
(2010 ASHRAE Handbook - Refrigeration Pg 1.2)
2°F drop = Capacity 96.4% Required Energy 104.8%
This table is for line loss, however it applies to evaporator...