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Digital controller for a cooling and heating plant having near-optimal global set point control strategy

  • US 5,963,458 A
  • Filed: 07/29/1997
  • Issued: 10/05/1999
  • Est. Priority Date: 07/29/1997
  • Status: Expired due to Term
First Claim
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1. A controller for controlling at least a cooling plant of the type which has a primary-only chilled water system, and the plant comprises at least one of each of a cooling tower means, a chilled water pump, an air handling fan, an air cooling coil, a condenser, a condenser water pump, a chiller and an evaporator, said controller being adapted to provide near-optimal global set points for reducing the power consumption of the cooling plant to a level approaching a minimum, said controller comprising:

  • processing means adapted to receive input data relating to measured power consumption of the chiller, the chilled water pump and the air handler fan, and to generate output signals indicative of set points for controlling the operation of the cooling plant, said processing means including storage means for storing program information and data relating to the operation of the controller;

    said program information being adapted to determine the optimum chilled water delta Tchw opt across the evaporator for a given load and measured delta Tchw, utilizing the formula;

    ##EQU53## where;

    
    
    space="preserve" listing-type="equation">K.sub.pump =P.sub.pump ×



    T.sub.chw).sup.3
    
    
    space="preserve" listing-type="equation">K.sub.fan =P.sub.fan ×



    T.sub.chw).sup.3and ##EQU54## said program information being adapted to determine the optimum chilled water supply set point utilizing the formula;

    
    
    space="preserve" listing-type="equation">T.sub.chws opt =T.sub.chw -deltaT.sub.chw optand to output a control signal to said cooling plant to produce said Tchws opt ;

    said program information being adapted to determine the optimum air delta Tair opt across the cooling coil utilizing the formula;

    ##EQU55## said program information being adapted to determine the optimum cooling coil discharge air temperature from the measured cooling coil inlet temperature using the formula;

    
    
    space="preserve" listing-type="equation">T.sub.opt cc disch =T.sub.cc inlet -delta T.sub.air optand to output a control signal to said cooling plant to produce said Topt cc disch.

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