Level-Master Control Oil and ammonia systems
For all practical purposes, ammonia and oil is not mixed (can not be mixed). Since the density of more oil than ammonia, it will fall to the bottom of any vessel containing a mixture when the mixture is relatively quiet. So. removal of oil from ammonia systems is a relatively easy task. As a rule, in systems equipped with a separator, liquid leg extended downward below the point where the liquid is fed off the evaporator. Adrain valve is designed for periodic manual discharge (see Fig. 11-47).
For flooded chillers that do not use the AC drum, sump drain valve, usually in the lower part of the hmm shell. These methods are quite satisfactory, except perhaps some of the low-temperature systems. Here, drainage leg or sump, as a rule, should be warmed up to attempts to delay the oil. Trapped oil becomes very viscous at low temperatures.
If not drain the oil from the sunken ammonia system, reduction of the evaporator heat-transfer rate may occur due to the increase of the refrigerant film resistance.
Difficulties in maintaining proper fluid level with any type of flooded management can also be expected.
With float valve, you can expect that the level of liquid in the evaporator increase with a high concentration of oil in the remote float chamber. If the level of master of management is used to insert, lamp installed in the remote camera, the concentration of oil in the lamps can cause overeating with possible flooding back. Lower or liquid-balance line should be free from the traps and be free flowing into the separator or cooler as shown in Fig. 11-48. Oil drain leg or sump must be in the lowest point on the underside.
HVAC Level-Master Control Oil return
All piston compressors will allow some oil into the discharge line of gas. Mechanical oil separators are widely used. However, they are never completely effective. In locked oil passes through the condenser liquid line, expansion unit and the evaporator.
A well-designed direct expansion system, speed refrigerant in the evaporator and the suction pipe is high enough to ensure continuous oil return into the compressor crankcase. However, this is not characteristic of flooded system. Here, the surge drum is designed for relatively low vapor speed. This prevents the drift of liquid refrigerant and further transfer into the suction line. This construction also prevents the return of oil with low-side in a normal manner.
If the oil is concentrated in the insert lamp location level master control, overfeeding with possible flooding back may occur. Trend overfeeding is due to the fact that the oil does not transfer heat from the low power of the heating element from a lamp as quickly as it makes pure liquid refrigerant. Light pressure higher than usual, and the valve remains in the open or partially open position...