ECOVALVE ELECTRONIC EXPANSION VALVE

Unique Capabilities:

• Control of refrigerant flow down to exceptionally low rates of 15 W or less of refrigeration.  A range of presently available orifice diameters enables flow control to 1200 W refrigeration, and higher flow rates are possible with a larger valve body.
• Maintains stable superheat of 3ºC, even at low flow rates.
• Physically small and easy to install by brazing into the liquid line at the evaporator inlet. The control unit is small, easily installed, and uses only 0.5W average power.
• Works with all common refrigerants, e.g., R134a, R22, R407C, isobutane, etc.  Can be adapted for CO2.
• Very low leakage reduces stop-start loss and minimum controllable flow.
• Ecovalve has been subjected to rigorous accelerated life tests, and showed no deterioration at the end of the equivalent of 15 years of service life.
• Digital control with an inexpensive microprocessor                                                 

Ecovalve operates on the pulsed-flow principle.  An electrically actuated reed valve* is pulsed open at two second intervals. Flow rate is proportional to the fraction of the pulse interval during which the reed valve is open.  That fraction is controlled by superheat as measured by thermistors. Stabilization of superheat is achieved with an inexpensive, passive, “superheat stabilizer”**, which performs the function of an expensive PID control and is, in its simplest form, a section of tubing typically 20 mm Diameter x 200 mm length, in the suction line preceding the thermistor that measures vapor temperature.

ECOVALVE Installation

Ecovalve is supplied with a thermistor wiring harness terminated with resistance-matched thermistors and a connector that plugs into the control. Connectors for the EEV actuator coil and for AC power to the control are also supplied.  If DC power for the control is available from existing supplies, a control without AC-DC power conversion is available at lower cost.

Specifications

Flow rate range is determined by orifice diameter, maximum duty cycle (duty cycle is defined as the ratio of valve-open time to pulse repetition interval), and minimum duty cycle.  Minimum duty cycle is necessary to restart superheat control after prolonged compressor-off during which the evaporator reaches temperature equilibrium.  Max. and min. duty cycles are hard-wired into the control according to customer requirements.

Orifice Diameter (mm.)       Max Duty cycle        Min Duty Cycle          Typical R134a 

                                                                                                          Refrigeration Range

                                                                                                                    (Watts)

            0.63                                0.90                         0.22                        146 - 600

            0.63                                0.67                         0.13                          87 - 446

            0.63                                0.43                         0.08                          53 - 287

For larger or smaller orifice diameters, refrigeration range can be approximated by: 

   Range with orifice Diameter D (mm.) = (D/0.63)3 x (range with 0.63 mm. orifice)

Orifice diameter will be supplied according to customer requirements.

Superheat set-point is 3.5ºC ±1ºC at midrange refrigeration and is hard wired into the control.  Superheat varies with duty cycle by approximately    

±2ºC, over the range of temperatures common in refrigeration.

December 2005:

The Coca-Cola Company, based on laboratory and field tests, endorses Global Cooling's expansion valve (sold as the "Ecovalve") as an option that can improve energy efficiency, increase the cooling capacity and lower initial pull-down time across a broad range of ambient operating temperatures of sales and marketing equipment. The installation of the Ecovalve is an effective tool to improve the environmental impact of new and refurbished sales and marketing equipment. A technical fact sheet is available on request or at www.globalcooling/gcjapan.html.

Please note that equipment that has been redesigned to include the Ecovalve would need to be submitted for re-certification to confirm performance and efficiency prior to our system's inclusion of the valve in its purchase plans.

*  U.S. Patent 5,967,488.  Other Patents pending

** U.S. Patent 6,260,368.  Other patents pending