Cold water unit as central air conditioning system of core equipment, in factory works air conditioning cold water unit of daily run process in the, often will encountered refrigeration unit "run oil" downtime of phenomenon, unit because run oil and triggered protection program action downtime, especially in winter low heat load of run workers condition Xia, unit occurred run oil phenomenon more frequently, and occurred this fault of unit most using of is full liquid type evaporator, this article on refrigeration unit low load workers condition Xia "run oil" problem and members with discussion share.

It is understood that there are many units on the market today are constructed in accordance with the following: refrigeration oil mixed with the refrigerant, oil separator to separate the unit freezing oil and refrigerant and the refrigerant through evaporator to compressor. This models refrigeration effect good, promotion degrees larger, but its run in the exists a problem, that is easy "run oil", dang cooling water temperature partial low Shi, exhaust had heat not high, to oil and refrigeration agent separation not completely, mixture into people hot Exchange device Hou led to unit low voltage partial low, more has is who will led to expansion valve jam caused unit cannot started of status.

Faults:

1, and oil separation device inside see not to frozen oil, at oil and no in condensation device within collection, but through has expansion valve into people to evaporator within, oil will stick to evaporator for hot copper tube surface Shang, makes evaporator of evaporation effect bad, caused evaporator within pressure partial low, while makes compressor of inhale overheating degrees is low and directly will refrigeration agent liquid sucking people, led compressor exhaust temperature is low, oil and refrigeration Agent still cannot separation, so of cycle will makes all of oil are collection in evaporator within, Makes great noise compressor because of insufficient oil supply until unit oil separator oil level alarm low y and automatically shuts down.

2, oil separators not see frozen oil, all of the oil with the exhaust to the condenser, ifwater temperature is low, then all the oil into the condenser and expansion valve oilplug evaporator due to insufficient immersion, pressure begin to fall, until the low pressure alarm stop. Above is known as the "oil spill". The main reason is because thefreezing water temperature is low, low exhaust temperatures.

Solution:

1, when found in the oil separator oil level decreases, the units will be transferred to the manual control mode immediately, limit the compressor load, for example: to limit its energy to 50%.

2, decreasing of cooling water flow rate, to enhance the water temperature so that the condensation pressure increase (if available, can use the bypass method to raisewater temperatures of the cooling water; or by Inverter control of cooling tower fanrunning or it directly off the cooling water temperature).

3, the unit's low-voltage alarm value and low voltage shut down to reduce to the extent permitted, as far as possible ensure that the unit is running.

4, if the oil level remains low, and the pressure in the evaporator is very low, to be taken into account if oil runs to the evaporator. From the evaporator as observed by the liquid inside is there a lot of white foam rolling, if there is, that oil in the evaporator, otherwise there may be condensation inside.

5, there are several steps above, after about half an hour (waiting time there difference between different units), the temperature of the cooling water and exhaust gas temperatures should rise to normal (R22 heat 17-22 degrees,

R134A superheat temperature 9-12 degrees), began to draw the oil below:

(A) oil in the evaporator. At close note frozen water of temperature, can first appropriate reduced its flow, let water water temperature reduced, then quickly increases flow, makes evaporator water temperature quickly increased, then of water temperature will over refrigeration agent of saturated temperature many, to makes refrigeration agent dramatic boiling, frozen oil will will with roll of refrigeration agent bubble was sucking people compressor, then compressor exhaust temperature should will declined some, but also should far over has oil and refrigeration agent of separation temperature, to will oil with back oil separation device and makes they separation. Repeated several times, oil will recover all the oil separator. Note each time you adjust water intervals, preferably before the exhaust temperature recovery after each adjustment to the regulation best.

(B) the oil inside the condenser. At this time do not need to pay much attention to the water temperature, as long as the normal operation of the unit will not have toomuch of a problem. Expansion valve should be opened gradually to the maximum(open process should not be too fast, preventing injury from too much immersion evaporator in copper tubes), wait a few minutes until the balance of high and low pressure units, you can see lots of white foam in the oil sight glasses of the evaporator,which was going into the oil from the condenser to the evaporator. As long as repeat (a) steps, oil will be back soon. To prevent such problems is to ensure as far as possible within the scope of the water temperature in the unit needs. If it is difficult tocontrol because of the climate, a bypass device may wish to add in the cooling water pipe. Best method should be called from procedures to control, connect the cooling tower fan with the unit controller, using unit temperature signal to control the cooling tower fan.

In addition, the refrigeration unit outage conditions, when the temperature is low,must not cut off refrigeration oil power, will set up a dedicated circuit, downtime toensure power supply is not interrupted, on low temperature lead to loss of oil because, after consulting the relevant professional literature, for the following reasons (forreference):

Refrigerator leader time downtime Hou, system in the refrigeration agent is environment temperature Xia of saturated, because environment temperature of changes, saturated temperature also in occurred changes, lubricants on refrigeration agent of solubility with of occurred changes, dang solubility variable hours, will has refrigeration agent precipitation, precipitation has two species way: gas phase and liquid phase, refrigeration agent liquid share about for 1.2, than oil heavy, will deposition in bottom, with environment temperature changes and periodic of changes, bottom liquid of refrigeration agent increasingly more, last will oil surface raised, Some oil overflow from the tank, causing "leakage".

On this phenomenon, it is recommended that measures:

Unit fuel tank design taking into account the adequate space and headroom to prevent overflow occurs after the oil level up;

Long downtime, keeping oil heater power supply is not interrupted, maintain the oiltemperature to prevent oil loss;

Addition can in tank bottom leads separate catheter, using Unicom device principle will accumulated in bottom of refrigeration agent liquid introduction back evaporator, such downtime Hou for tank bottom refrigeration agent increased, oil bit up to only rose to catheter of level turn height at, for avoid catheter within appeared siphon, catheter need set anti-siphon device, such can in downtime power of situation Xia avoid unit "run oil"

As a facility operator, the simplest solution is the unit down for a long time, do not interrupt the unit heating power, this is the most simple and practical approach;