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Condenser Pressure Control System and Method

a technology of condenser fan and control system, which is applied in the direction of refrigeration machines, climate sustainability, refrigeration safety arrangements, etc., can solve the problems of controlling the condenser fan, reducing the power of the compressor, and excessive compressor power consumption

Inactive Publication Date: 2018-02-01
LIU MINGSHENG +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a method for controlling a condenser fan of a heating, ventilating, and air-conditioning (HVAC) system to maintain a valve position of an expansion valve of the system at a setpoint. This is achieved by providing a controller in communication with the expansion valve and a refrigerant flow sensing device. The controller compares the refrigerant flow rate with a critical flow rate value and modulates the condenser fan to maintain the valve position at the setpoint when the refrigerant flow rate is higher than the critical flow rate value. This method ensures efficient operation of the HVAC system and provides better control over the refrigerant flow rate and pressure.

Problems solved by technology

This in turn results in the excessive consumption of compressor power.
While this prior art system is functional, there are certainly problems with controlling the condenser fan to maintain the condensing temperature or pressure at a single setpoint.
Therefore, optimizing the head pressure can significantly reduce the power of the compressor.
An additional problem is that under the design head pressure the expansion valve can malfunction when the refrigerant flow rate is low.
Prior art systems, such as the one shown in FIG. 1, tend to rely solely on the thermal bulb to control the position of the expansion valve and are thus not able to optimally regulate the flow of refrigerant.

Method used

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  • Condenser Pressure Control System and Method
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  • Condenser Pressure Control System and Method

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first embodiment

[0095]In the disclosure, herein referred to as expansion valve based configuration I 200 and shown in FIG. 2 of the drawings, the condenser fan is controlled to directly maintain the position of expansion valve 214 at a position close to the maximum. This position is measured or given by controller 222. In the method of the embodiment, controller 222 is configured within the existing refrigeration system in connection with expansion valve 214 and is configured to collect signal information on the valve position of the expansion valve. In the figure shown, the existing refrigeration system comprises flow meter 212, evaporator 216, condenser 206, condenser fan 220, compressors I 218 and II 219, expansion valve 214, thermal bulb 224, and variable frequency drive (VFD) II 240 (this VFD is used to control condenser fan 220).

[0096]Controller 222 is implemented so that it is configured in communication with flow meter 212, VFD II 240 and compressors I 218 and II 219 of the existing refrige...

second embodiment

[0098]In the second embodiment, herein referred to as expansion valve based configuration II 300 and shown in FIG. 3 of the figures, controller 222 measures the pressure across expansion valve 214 of the refrigeration system. As in the first configuration (system 200), controller 222 is configured in communication with an existing refrigeration system comprised of compressors 218 and 219, condenser fan 220 (in condenser 206), evaporator 216, expansion valve 214, thermal bulb 224 and VFD II 240. Flow meter 312 is also configured in the HVAC system in connection with controller 222. In some embodiments the flow meter can be installed into the existing refrigeration system while in others it may be a part of the already existing refrigeration system.

[0099]Controller 222 is configured to receive a signal indicating the valve position of expansion valve 214 of the existing system. At least one pressure sensor is also implemented in the existing system at the inlet of the expansion valve ...

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Abstract

A method of controlling a condenser fan of a heating, ventilating, and air-conditioning (HVAC) system based on a comparison of a refrigerant flow rate to maintain a valve position of an expansion valve. In the method, a controller modulates the condenser fan to maintain the valve position of the expansion valve at a valve position setpoint when the refrigerant flow rate is higher than the critical flow rate. The method also comprises controlling the speed of the condenser fan of the HVAC system to maintain a condensing measurement at a plurality of condensing measurement setpoints when the refrigerant flow rate is higher than the critical flow rate. The method also comprises controlling the speed of the condenser fan to maintain a condensing measurement at a plurality of condensing measurement setpoints when the condensing temperature measurement is higher than an ambient air temperature value plus at or around 5° F.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]Not ApplicableSTATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT[0002]Not ApplicableREFERENCE TO SEQUENCE LISTING, A TABLE, OR A COMPUTER PROGRAM LISTING COMPACT DISC APPENDIX[0003]Not ApplicableTECHNICAL FIELD[0004]The disclosed embodiments generally relate to a system and method for controlling condenser fans, and more particularly for controlling condenser fans in HVAC (heating, ventilation, and air conditioning) units as well as commercial and industrial refrigeration system applications.DESCRIPTION OF THE RELATED ART[0005]Condensers are devices that condense a substance from a gaseous state to a liquid state. Air-cooled condensers enable this phase change using ambient air, while water cooled condensers use water as the cooling means. They are a common component of air conditioning and refrigeration systems. A condenser control system may include at least one VFD (variable frequency drive) for modulating the speed of the...

Claims

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Application Information

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Patent Type & Authority Applications(United States)
IPC IPC(8): F25B49/02
CPCF25B49/027F25B2700/13F25B2600/111F25B2600/2513F25B2700/195F25B2700/171F25B2700/2116F25B2700/2106F25B2500/19F25B2400/075F25B2600/17F25B2700/1332F25B2700/21163Y02B30/70
Inventor LIU, MINGSHENGSUN, CHANGLINSANDERS, CHRISTOPHER L.
Owner LIU MINGSHENG