Active Charge Control Design
The patented Active Charge Control (ACC) consists of a thermally-insulated reservoir which replaces the standard accumulator. Its purpose is to constantly deliver refrigerant vapor and oil to the compressor in the optimum condition and quantity. This control provides a means of bringing vapor from the evaporator into contact with liquid refrigerant stored within its reservoir. Liquid from the reservoir flows through an orifice into an evaporator tube in the ACC through which the incoming vapor passes. The liquid is entrained in the vapor stream and circulated back to the reservoir by way of a deflector plate at the exit of the evaporator tube. If the incoming vapor is superheated, this contact with the liquid evaporates some of the stored liquid, thus reducing the superheat to near zero.
Conversely, if the incoming vapor contains liquid refrigerant, that liquid is trapped in the reservoir. In either event, the vapor leaving the ACC on its way to the compressor has near zero superheat and contains no liquid refrigerant. Incoming refrigerant from the evaporator is continuously mixed with liquid refrigerant which passes through an orifice from the liquid reservoir of the ACC. The turbulence of the liquid/vapor mix in the tube causes foaming and misting of the oil within the mix. A circular deflector plate above the inlet tube deflects the mixture radially outward and thus reduces the velocity of the mix as it continues to move outward. All refrigerant vapor which has no liquid in it is drawn upward to the outlet at the top. Oil mist is entrained in this vapor and exits also. Liquid refrigerant droplets and any foam bubbles containing liquid refrigerant are too heavy to be entrained in the vapor stream and therefore fall into the reservoir of liquid refrigerant. Any liquid refrigerant arriving at the ACC inlet from the evaporator is deflected and trapped in the reservoir by the same action. All liquid refrigerant must evaporate to leave the ACC, ensuring that no liquid refrigerant returns to the compressor.
The ACC also provides a reserve of refrigerant so that the amount of charge in the system is not critical. The combined functions of the ACC serve to increase the active charge in circulation in the system if vapor reaching the ACC is superheated; or reduces the system charge if arriving vapor contains liquid refrigerant. Consequently, the system operates with an optimum refrigerant charge in active circulation under all loading conditions, thereby providing optimum system efficiency.
The ACC provides a means of quickly and easily determining when the system is properly charged-without gauges, wet and dry bulb thermometers, and charging charts. To determine if the system is properly charged, you need only observe the liquid level by looking through sight glasses mounted on the side of the ACC.
ACC Functions
Prevents any liquid or unevaporated refrigerant from reaching the compressor.
Continuously allows the passage of compressor oil entrained in the refrigerant.
Serves as a reservoir supplying the varying active refrigerant charge requirements, as well as compensating for any possible small amounts of leakage.
Evaporates or traps refrigerant as necessary to keep the system properly charged, the evaporator "flooded", and to prevent the buildup of superheat at the compressor inlet.
Increases suction pressure by eliminating superheat.
Allows the compressor to run cooler, thus increasing its service life.
Improves volumetric efficiency of the compressor (cooler vapor is denser than superheated vapor).
By increasing suction pressure, increases mass flow, thereby increasing efficiency.
Provides a means for quickly and easily determining whether the system is properly charged.
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