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WO1998006987A1 - Perfectionnements s'appliquant a la regulation de refrigeration - Google Patents

Perfectionnements s'appliquant a la regulation de refrigeration Download PDF

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Publication number
WO1998006987A1
WO1998006987A1 PCT/AU1997/000522 AU9700522W WO9806987A1 WO 1998006987 A1 WO1998006987 A1 WO 1998006987A1 AU 9700522 W AU9700522 W AU 9700522W WO 9806987 A1 WO9806987 A1 WO 9806987A1
Authority
WO
WIPO (PCT)
Prior art keywords
temperature
vapour
condenser
refrigeration system
compression refrigeration
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/AU1997/000522
Other languages
English (en)
Inventor
Roderick Alan Hislop
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Individual
Original Assignee
Individual
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Individual filed Critical Individual
Priority to AU37630/97A priority Critical patent/AU3763097A/en
Publication of WO1998006987A1 publication Critical patent/WO1998006987A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B49/00—Arrangement or mounting of control or safety devices
    • F25B49/02—Arrangement or mounting of control or safety devices for compression type machines, plants or systems

Definitions

  • THIS INVENTION relates to the control of refrigeration systems, and more particularly to a method for minimising the energy consumption of vapour- compression refrigeration systems during operation, especially under low load conditions
  • Vapour-compression refrigeration system generally consist of a compressor, two heat exchangers (a condenser and an evaporator), an expansion valve and a refrigerant
  • the operation of a vapour-compression refrigeration system has a number of stages Firstly, the refrigerant enters the compressor as a low pressure gas at the evaporating (or suction) temperature wherein it is compressed into a high temperature, high pressure gas
  • the hot refrigerant gas is then cooled to liquid form in the condenser before being pumped, or passing under its own pressure, across the expansion valve to the evaporator
  • the refrigerant changes into a low pressure, low temperature liquid which is then able to absorb heat in the evaporator
  • the absorption of heat in the evaporator causes the liquid to boil into a gas before being compressed again
  • the condensing medium Whilst there are many different types of condensing media, the most commonly used is simply ambient air and/or ambient water. .
  • the condensing medium may take the form of some other process liquid or gas transported by pumps or fans, respectively.
  • the cool water from the cooling tower is pumped around the condensing heat exchanger containing the refrigerant. As it does so, heat is rejected into the water. The amount of heat rejected is proportional to the water flow around the condenser. Increasing the water flow increases the rate of heat transfer from the refrigerant for a given ambient water temperature, and therefore reduces the condensing temperature.
  • Evaporative condensers on the other hand, utilise the cooling powers of evaporating water in an air stream directly over the condensing heat exchanger containing the refrigerant as the method of heat rejection.
  • the rate and amount of heat rejection is dependent on both the condensing temperature and the air flow rate about the condenser. Increasing the air flow increases the rate of heat transfer from the refrigerant, for a given ambient air temperature, and therefore reduces the condensing temperature.
  • a vapour- compression refrigeration system and more particularly the condenser, involves preselecting a discharge pressure or temperature for the refrigerant and maintaining that pressure or temperature at a constant level, known as a "set point", whenever the refrigeration system is operating. In practice, this involves measuring the pressure or temperature of the refrigerant and adjusting the working parameters of the condenser to suit. This method of control is known as the Constant Condenser Temperature (CCT) method.
  • CCT Constant Condenser Temperature
  • the CCT method is very cost effective for peak design conditions, typically peak summer conditions, but such conditions typically occur for only 1-2% of the time. At other times of the year or under lower load conditions, the condensing set point is too high and a great deal of energy is wasted. Even when the set point is reduced to a level below that used for peak summer design conditions, the system will only be operating at the optimum efficiency for the few specific ambient and refrigeration load conditions
  • FCT Floating Condenser Temperature
  • vapour-compression refrigeration systems are more efficient for lower condensing temperatures and for high evaporating temperatures (and pressures) because the pressure ratio of compression is reduced Typically the improvement in efficiency ranges from 1 5%/l°c to 3%/l°c for most refrigeration applications
  • the evaporating or condensing equipment require increased energy input in order to reduce the condensing temperature
  • the cooling tower fans need to operate at higher speeds, thus using more energy
  • the current invention is described herein with particular reference to large refrigeration plants which use water cooled cooling towers or evaporative condensers for condensation, it will be readily understood by those skilled in the art that it has application to refrigeration systems which employ alternative condensing and evaporating means.
  • a method of controlling the operation of a vapour-compression refrigeration system so that total energy consumed by the system during operation is reduced comprising the steps of-
  • the refrigeration load is determined by the required "heat rejection", that is, the amount of heat to be removed from the refrigerant, and also the ambient temperature.
  • the ambient temperature is described in terms of the ambient dry bulb temperature when an air cooled condenser is used, and in terms of the ambient wet bulb temperature when a water cooled cooling tower or evaporative condenser is used.
  • vapour-compression refrigeration systems work most efficiently when the temperature of the condenser cooling water is selected and maintained within a predetermined range relative to the ambient wet bulb temperature
  • a method for controlling the operation of a vapour-compression refrigeration system which includes a water cooled condenser (as hereinafter defined) so that the total energy consumed by the system during operation is reduced, the method comprising the steps of -
  • the invention can be used to control the evaporating temperature and evaporator fan speed
  • water cooled condenser as used herein is intended to include any condenser which utilises the cooling properties of water, including direct water cooled condensers, condensers through which water from a cooling tower is pumped or evaporative condensers.
  • each temperature is intended to mean the difference in temperature between the wet bulb temperature and the condensing water temperature for water cooled condensers and is intended to mean the difference in temperature between the dry bulb temperature and the condensing vapour temperature for air cooled condensers.
  • FIGURE 1 is a graph showing the operating efficiency for a Luke HRWC- 900C refrigeration system across a range of approach temperatures with consumption in kilowatts plotted on the Y axis and the approach temperature in degrees Celsius on the X axis and.
  • FIGURE 2 is a graph showing the operating efficiency of the same Luke HRWC-900C refrigeration system at an ambient wet bulb temperature of 16° Celsius under a range of refrigeration loads with water cooled cooling tower and condenser controlled by the Constant Condenser Temperature method, the Floating Condenser Temperature method, the Applicant's Adjustable Approach Temperature method with on/off speed drive fans (AAT on/off) and the Applicant's Adjustable Approach Temperature method with variable speed drive fans (AAT VSD) respectively, with total power consumption in kilowatts plotted on the Y axis and % refrigeration load on the X axis.
  • Constant Condenser Temperature method the Floating Condenser Temperature method
  • AAT on/off Applicant's Adjustable Approach Temperature method with on/off speed drive fans
  • AAT VSD Applicant's Adjustable Approach Temperature method with variable speed drive fans
  • FIGURE 3 is a graph showing the operating efficiency of the variable speed drive fans and on/off speed drive fans of a Luke HRWC-900C refrigeration system across a range of approach temperatures with power consumption in kilowatts plotted on the Y axis and the approach temperature in degrees Celsius on the X axis.
  • the Applicant has made the discovery that the minimum energy consumed by a vapour-compression refrigeration system is related to the approach temperature with the minimum total energy being consumed for a similar approach temperature or range of temperatures regardless of other variables
  • the Applicant then measured the energy consumed by the Luke HRWC-900C refrigeration system when controlled by the method of the current invention and compared it with the energy consumed by the same refrigeration system when controlled by existing methods. The results of these trials are illustrated in Figure 2 where total power consumption in kilowatts is plotted on the Y axis and the percentage refrigeration load is plotted on the X axis.
  • the diamond-marked solid line represents the energy consumption of the Luke HRWC-900C refrigeration system when controlled by the Constant Condenser Temperature method.
  • the square-marked dotted line represents the energy consumption of the Luke HRWC-900C refrigeration system when controlled by the Floating Condenser Temperature method.
  • the triangle-marked dotted line represents the energy consumption of the Luke HRWC-900C refrigeration system when controlled by the Applicant's Adjustable Approach Temperature method with on/ofF speed drive fans.
  • the cross-marked dotted line represents the energy consumption of the Luke HRWC-900C refrigeration system when controlled by the Applicant's Adjustable Approach Temperature method with variable speed drive fans.

Landscapes

  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Air Conditioning Control Device (AREA)

Abstract

La présente invention concerne un procédé de régulation du fonctionnement d'un système de réfrigération à compression de vapeur permettant de réduire l'énergie totale consommée par le système pendant son fonctionnement. Le procédé comporte plusieurs opérations: 1) mesurer la demande de froid et l'un au moins des paramètres des conditions ambiantes; 2) calculer l'énergie totale consommée par le compresseur (les compresseurs), l'évaporateur (les évaporateurs), le condenseur (les condenseurs) et le ventilateur (les ventilateurs) avec la demande froid considérée et le paramètre considéré des conditions ambiantes; 3) régler le point de consigne de pression ou de température concernant le condenseur (les condenseurs) et/ou l'évaporateur (les évaporateurs) pendant que le système fonctionne, de façon à réduire l'énergie totale consommée par le système tout en tenant compte de la demande réfrigération considérée et du paramètre considéré des conditions d'ambiance.
PCT/AU1997/000522 1996-08-15 1997-08-15 Perfectionnements s'appliquant a la regulation de refrigeration Ceased WO1998006987A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU37630/97A AU3763097A (en) 1996-08-15 1997-08-15 Improvements in refrigeration control

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
AUPO1693 1996-08-15
AUPO1693A AUPO169396A0 (en) 1996-08-15 1996-08-15 Improvements in refrigeration control

Publications (1)

Publication Number Publication Date
WO1998006987A1 true WO1998006987A1 (fr) 1998-02-19

Family

ID=3796006

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/AU1997/000522 Ceased WO1998006987A1 (fr) 1996-08-15 1997-08-15 Perfectionnements s'appliquant a la regulation de refrigeration

Country Status (2)

Country Link
AU (1) AUPO169396A0 (fr)
WO (1) WO1998006987A1 (fr)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0895038A1 (fr) * 1997-07-29 1999-02-03 LANDIS & STAEFA, INC. Régulateur digital pour une installation de chauffage ou de refroidissement avec une stratégie de cÔntrole selon la méthode de la valeur de consigne globale étant approxivativement optimale
WO2000033707A1 (fr) 1998-12-09 2000-06-15 Nevoret-Concept Meuble frigorifique de vente
WO2002086396A1 (fr) * 2001-04-20 2002-10-31 York International Corporation Procede et dispositif d'evacuation de la chaleur du condenseur d'un systeme de refrigeration

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2283405A1 (fr) * 1974-06-26 1976-03-26 Seitha Procede et dispositif de regulation d'un systeme frigorifique destine a une production de froid et de chaleur
EP0066553A1 (fr) * 1981-05-15 1982-12-08 INDESIT S.r.l. Système de commande pour améliorer le rendement d'appareils de chauffage ou de refroidissement
EP0355180A2 (fr) * 1988-08-17 1990-02-28 Nippon Telegraph And Telephone Corporation Refroidisseur et procédé de régulation
GB2273974A (en) * 1992-12-18 1994-07-06 Danfoss As Controlling the superheat temperature of a refrigeration system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2283405A1 (fr) * 1974-06-26 1976-03-26 Seitha Procede et dispositif de regulation d'un systeme frigorifique destine a une production de froid et de chaleur
EP0066553A1 (fr) * 1981-05-15 1982-12-08 INDESIT S.r.l. Système de commande pour améliorer le rendement d'appareils de chauffage ou de refroidissement
EP0355180A2 (fr) * 1988-08-17 1990-02-28 Nippon Telegraph And Telephone Corporation Refroidisseur et procédé de régulation
GB2273974A (en) * 1992-12-18 1994-07-06 Danfoss As Controlling the superheat temperature of a refrigeration system

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0895038A1 (fr) * 1997-07-29 1999-02-03 LANDIS & STAEFA, INC. Régulateur digital pour une installation de chauffage ou de refroidissement avec une stratégie de cÔntrole selon la méthode de la valeur de consigne globale étant approxivativement optimale
US5963458A (en) * 1997-07-29 1999-10-05 Siemens Building Technologies, Inc. Digital controller for a cooling and heating plant having near-optimal global set point control strategy
WO2000033707A1 (fr) 1998-12-09 2000-06-15 Nevoret-Concept Meuble frigorifique de vente
FR2786999A1 (fr) 1998-12-09 2000-06-16 Nevoret Concept Meuble frigorifique de vente
WO2002086396A1 (fr) * 2001-04-20 2002-10-31 York International Corporation Procede et dispositif d'evacuation de la chaleur du condenseur d'un systeme de refrigeration
US6530236B2 (en) 2001-04-20 2003-03-11 York International Corporation Method and apparatus for controlling the removal of heat from the condenser in a refrigeration system
EP1811249A1 (fr) * 2001-04-20 2007-07-25 York International Corporation Procede et dispositif d`evacuation de la chaleur du condenseur d`un systeme de refrigeration

Also Published As

Publication number Publication date
AUPO169396A0 (en) 1996-09-05

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