Liquid Flow Control Design

ECR's proprietary Liquid Flow Control (LFC) replaces TXVs, EXVs, AXVs, fixed orifices, or capillary tubes. It regulates the rate of liquid flow from the condenser by responding directly to the amount of vapor bubbles arriving from the condenser. Thus, the system positively meters the liquid flow to the evaporator and passes liquid at the rate it is produced in the condenser.

By using the vapor signal from the condenser, the LFC continuously modulates the rate of liquid flow to assure that vapor is present throughout the whole condenser, thereby eliminating subcooling. In addition, the LFC prevents vapor from "blowing through" from the condenser to the evaporator. By eliminating subcooling, more of the area of the condenser actively condenses vapor into liquid. As a result, the compressor discharge pressure is reduced and mass flow is increased, thus increasing efficiency.





LFC Functions
Coordinates with the condenser to set the proper rate of refrigerant flow for the entire system.
Prevents vapor from "blowing through" the condenser.
Ensures zero subcooling so that all of the condenser surface is active.
Reduces discharge pressure.
Increases mass flow as a result of lowered discharge pressure, thereby increasing efficiency.
Additional Control SystemBenefits
The ability of the ACC to hold unevaporated refrigerant in reserve and vary the amount of charge in circulation to exactly match the changing load on the system has other benefits:

The length and orientation of the evaporator-condenser and the amount of refrigerant charge are not crucial, thus earth loops can be installed in vertical, diagonal or horizontal configurations.
EarthLinked® can provide optional domestic water heating either by "desuperheating" or through a simple full-condensing integrated "on-demand" water heating system.
Installation and service of the system are simplified by the ease and certainty of determining a correct charge without the need for gauges, thermostats and "weighing in" of refrigerant under any weather conditions.
Simplicity of the controls assures system reliability.

Of all the instruments utilized in the HVAC/R trades - I trust analog gauges the least.

The design is proprietary to ECR Technologies and I believe it was developed as an integral component to their DX geo thermal and geo exchange equipment. It is also claimed to elevate efficiency levels of equipment manufactured by others. The component illustrated schematically in the OP appears like this in the flesh, so to speak: [Thumbnailed image was all I could locate].



They also hold proprietary patents on a variational design of the standard accumulator [read about it here: http://hvacprotech.forumwise.com/hvacprotech-thread3793.html ], that when incorporated with the flow control design in the OP is said to result in amazingly high efficiency ratings. More about the system:

ECR REFRIGERANT FLOW CONTROLS

Direct GeoExchange is today's most effective method of harvesting the earth's renewable energy for the purpose of providing domestic hot water and heating/cooling for buildings. Highly versatile, ECR's refrigerant flow controls have successfully operated commercial refrigeration systems, air source heat pumps from one to 15-ton capacity, a variety of GeoExchange systems produced by five manufacturers, closed-loop units of three manufacturers, multi-compressor units, and radiant hydronic heating systems. These unique flow controls also make possible the inclusion of desuperheating or integrated water heating on any heat pump system without the need for electronic controls.

Until the development of ECR's Refrigerant Flow Controls, no simple controls or metering devices existed that could deliver refrigerant in the condition appropriate to each component throughout the entire operating cycle and continually maintain stable refrigerant conditions.

Special refrigerant flow controls were necessary to manage the refrigerant in the long evaporator-condenser which is buried in direct contact with the heat source. ECR's refrigerant management system serves this need and provides multiple additional advantages.

Refrigerant Management Objectives

•Stable refrigerant management in long evaporator/condenser under all loading conditions.
•Continuously return lubricating oil to the compressor without any liquid refrigerant.
•Improved system efficiency, reliability and serviceability.

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Detailed description of how the system works in the Heating Mode: How the System Works in the Heating Mode In the heating mode, the refrigerant enters the earth loops as a cold liquid (blue in the graphic) and comes out as a cool vapor (green in the graphic). When a refrigerant evaporates it absorbs a large quantity of heat from any surrounding material. Therefore as the refrigerant flows through the loops, it absorbs heat from the earth and stores it in vapor form for later release. The cool (green) vapor that is heat-charged after leaving the earth loops then enters the compressor where its temperature is raised from about 40o F to about 160o F. During this compression stage, the temperature of the vapor increases because of the intense compression and the vapor leaves the compressor (red in the graphic) hotter than the air in the building being heated. Because the vapor leaving the compressor and entering the condenser is hotter than the inside air, heat flows into the air flow from the vapor as the air passes the blower. This warms your home. As the heat is removed while the hot vapor passes through the condenser, the vapor condenses more and more until it exits the condenser as a liquid. This warm liquid (yellow in the graphic) enters the flow control unit, which monitors the amount of vapor arriving at the liquid flow control (LFC), and meters liquid only through the device for its return to the earth loop field.

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Detailed description of how the system works in the Cooling Mode: How the System Works in the Cooling Mode In the cooling mode, cool vapor (green in the graphic) arrives at the compressor after absorbing heat from the air in the building. The compressor compresses the cool vapor into a smaller volume, increasing its heat density. The refrigerant exits the compressor as a hot vapor (red in the graphic) which then goes into the earth loop field. The loops act as a condenser condensing the vapor until it is virtually all liquid. The refrigerant leaves the earth loops as a warm liquid (yellow in the graphic). The flow control regulates the flow from the condenser such that only liquid refrigerant passes through the control. The refrigerant expands as it exits the flow control unit and becomes a cold liquid (blue in the graphic). Because the liquid evaporates as it passes through the cooling coil located in the air handler, it absorbs heat from the air blowing over the coil surface and thus cools your home.

To operate at optimum efficiency, the three major components of all heat pumps require the refrigerant to be in a particular physical state appropriate to each component (the compressor, condenser and evaporator). The compressor needs a dry refrigerant vapor from the evaporator, containing little or no superheat at the compressor inlet. The condenser needs its refrigerant outlet pressure to be just sufficient to cause the refrigerant vapor to complete its condensing just before it reaches the condenser outlet. This provides high pressure vapor to the entire condenser for maximum condensing with no uncondensed vapor passing through the condenser and no liquid refrigerant "backed up" in the condenser (which produces subcooling).



In contrast, the evaporator needs liquid refrigerant at its inlet. The liquid should then complete its evaporation just as it reaches the evaporator outlet. This is the optimum "flooded" evaporator condition which produces maximum system efficiency when no portion of the evaporator is wasted in producing superheat. Any unevaporated refrigerant which passes through or out of the evaporator should not reach the compressor.

Conventional controls include thermostatic expansion valves (TXVs), electronic expansion valves (EXVs), automatic expansion valves (AXVs), fixed orifices, capillary tubes, and accumulators. No combination of these can assure simple, stable operation of a Direct GeoExchange system or achieve all the following conditions which ECR's controls maintain in any standard air conditioning system, including:

•A fully condensing condenser (minimal subcooling).
•A continuously flooded evaporator (no superheat).
•Dry vapor with no superheat at the compressor inlet.
•A simple, easy method of determining when the system is properly charged.

Other Applications

The inherent simplicity and adaptability of ECR controls has been proven since 1984. These controls have increased the efficiency of a variety of systems produced by 16 different manufacturers, including air source heat pumps (15% efficiency gain), air conditioners; closed loop GeoExchangers (loop length can be reduced by approximately one-fourth because of system efficiency introduced by the ACC and LFC); hundreds of other Direct GeoExchange systems (including inoperable and inefficient units previously produced by others); Direct GeoExchange water heaters; and radiant hydronic systems which also produce domestic hot water.

Of all the instruments utilized in the HVAC/R trades - I trust analog gauges the least.