EP0152608B1 - Control method for a compound refrigeration plant - Google Patents

Control method for a compound refrigeration plant Download PDF

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Publication number
EP0152608B1
EP0152608B1 EP84115860A EP84115860A EP0152608B1 EP 0152608 B1 EP0152608 B1 EP 0152608B1 EP 84115860 A EP84115860 A EP 84115860A EP 84115860 A EP84115860 A EP 84115860A EP 0152608 B1 EP0152608 B1 EP 0152608B1
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Prior art keywords
fans
temperature
pressure
approx
volume flow
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EP84115860A
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German (de)
French (fr)
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EP0152608A3 (en
EP0152608A2 (en
Inventor
Herbert Hansen
Herbert Hartmann
Siegfried Dipl.-Ing. Haaf
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Linde GmbH
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Linde GmbH
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Priority to AT84115860T priority Critical patent/ATE39180T1/en
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    • 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
    • F25B49/027—Condenser control arrangements
    • 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
    • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
    • F25B2400/07—Details of compressors or related parts
    • F25B2400/075—Details of compressors or related parts with parallel compressors
    • 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
    • F25B2400/00—General features or devices for refrigeration machines, plants or systems, combined heating and refrigeration systems or heat-pump systems, i.e. not limited to a particular subgroup of F25B
    • F25B2400/22—Refrigeration systems for supermarkets
    • 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
    • F25B2700/00—Sensing or detecting of parameters; Sensors therefor
    • F25B2700/21—Temperatures
    • F25B2700/2116—Temperatures of a condenser
    • F25B2700/21161—Temperatures of a condenser of the fluid heated by the condenser

Definitions

  • the invention relates to a method for controlling a composite refrigeration system with a plurality of compressors and at least one fan for removing the condensing heat, in which the air volume flow of the fan or fans is changed as a function of the air intake temperature and the cooling capacity.
  • a composite refrigeration system essentially consists of several compressors with a common suction line and a common pressure line, a condenser and several evaporators as well as expansion elements which are assigned to the evaporators.
  • the condenser is assigned one or more fans which dissipate the heat generated during the liquefaction of the refrigerant.
  • a certain number of compressors and a certain number of fans are in operation.
  • the operation of the compressors and fans requires a high drive energy. To reduce this, compressors are therefore usually switched off during part-load operation, while the condenser fan or fans continue to be operated at full air output. Although this can achieve a certain reduction in energy consumption, the result of this measure is that the application range of the expansion valves is exceeded.
  • DE-A-3 025 439 describes a cooling system in which one of three cooling fans of the condenser is actuated as a function of the temperature of the air drawn in.
  • the control option is limited to switching this blower on and off at a fixed threshold air intake temperature.
  • US-A-3 739 596 shows a cooling system which is controlled in dependence on the condensing pressure by switching two condensing fans on and off directly by means of pressure switches located in front of the condenser.
  • a similar method is described in GB-A-2 067 275.
  • it is proposed to switch the condenser fans on or off depending on the condensing pressure.
  • the object of the invention is to optimize the ratio of the cooling capacity of the compressors to the power consumption of the compressors and fans, that is to say to minimize the total power consumption in particular with a predetermined cooling capacity.
  • the area of application of the expansion valves should be maintained compared to the known method and the condensing pressure should be optimized.
  • This object is achieved according to the invention in that the air intake temperature T A and the condensing pressure p c are measured and a setpoint Pe , s of the condensing pressure which is dependent on the air intake temperature is set.
  • the instantaneous cooling capacity is recorded indirectly via the condensing pressure.
  • the measured condensing pressure is compared with a setpoint, the calculation of which includes the air intake temperature and system-specific parameters.
  • the air volume flow of the fan or fans is increased or decreased.
  • This regulation of the air volume flow of the condenser fans allows a particularly favorable adaptation of the fan performance to the two parameters air intake temperature and cooling capacity.
  • the optimal number of condenser fans can be switched on for a predetermined number of compressors in operation. In general, a reduced air volume flow is used. The resulting savings can drive the energy required to drive the condenser fans, making the method according to the invention particularly economical.
  • the regulation of the air volume flow according to the invention is in particular provided such that the air volume flow is reduced at a lower air intake temperature.
  • a lower air intake that is, lower the outside temperature is, driven in a start-first full air output, and then the air power is reduced for example by reducing the speed of the fans to 2/3 of the original value.
  • a predetermined range of the condensing pressure must be maintained in a development of the inventive concept. This range is limited on the one hand by a minimum pressure, which is necessary for the expansion valves to work properly, and on the other hand, by a maximum pressure, which is determined by the application limits of the refrigerant compressors.
  • the range of condensing pressure to be observed also depends on the refrigerant used.
  • the range of common refrigerants such as R 22 and R 502 is, for example, between approx. 10 bar and approx. 20 bar.
  • the parameters A and B depend on the properties of the refrigerant used and on the conditions of the refrigeration system.
  • the control of a composite refrigeration system is also provided, in which additional heat recovery is provided for space heating and domestic water heating.
  • the air volume flow is additionally regulated as a function of the hot water supply temperature and / or the room temperature.
  • the evaporation pressure of the refrigerant is increased when the cooling requirement drops. If the ambient temperature and thus the cooling requirement decrease, the evaporation temperature and thus the evaporation pressure of the refrigerant is increased.
  • the lower pressure difference between evaporation and condensing pressure means that less energy has to be applied for compression.
  • the inventive method is applicable to all composite refrigeration systems, such. B. for chilled and frozen sales furniture in supermarkets, for slaughterhouses, cold stores or process engineering systems.
  • compressors 1a, 1b, 1c and 1d connected in parallel are connected to a collecting container 7 via a common suction line 4, a plurality of evaporators 5 and expansion valves 6.
  • evaporators 5 and expansion valves 6 For the sake of simplicity, only one evaporator and one expansion valve are shown, but in practice several evaporators and expansion valves are usually connected in parallel.
  • Liquid refrigerant is stored in the collecting container and fed to the evaporators via the expansion valves 6.
  • the refrigerant suction gas in line 4 is then evenly distributed to the individual compressors of the composite system and sucked in by them.
  • Compressed refrigerant vapor is then passed into a common pressure line 8 and to a condenser 9, in which the vapors are condensed and released in liquid form via line 10 into the collecting container 7.
  • the condenser 9 is equipped with fans 11, 12 which are connected to a control unit 13.
  • the air volume flow circulated by the fans is conducted via the condenser and removes the heat of condensation, so that the refrigerant condensation can take place in the condenser.
  • a temperature sensor 14 is connected to the control unit 13 and detects the temperature in the air intake duct of the condenser.
  • the condenser is also assigned a pressure transmitter 20, which is also connected to the control unit 13.
  • a condenser 15 is also provided in line 8, in which the condensation heat can be used for heating domestic water and / or for space heating.
  • water from the space heating circuit is supplied via line 16 and heated in the condenser 15.
  • a boiler 17 can also be switched on.
  • the hot water is returned to the heat consumers via a pump 18.
  • a heating controller 19, which is connected to the control unit 13, is assigned to the boiler.
  • Parameters A and B are used to adapt to the respective refrigerant and system-specific conditions.
  • the refrigerating capacity can be adapted to this requirement by raising the evaporating temperature (increasing the evaporating pressure) of the refrigerant. As a result, the pressure difference to be overcome by the compressors is reduced, which leads to a corresponding energy saving.
  • the process according to the invention proceeds somewhat differently with heat recovery.
  • the fans are switched as a function of the heating controller 19, which detects the water flow temperature and whose setpoint is shifted from the outside temperature. If the heat of condensation in the condenser 15 is not sufficient to ensure the necessary heating of the water, the boiler 17 is additionally switched on. If the condensing pressure rises to an adjustable first upper limit value during heat recovery, the boiler 17 is still controlled by the heating controller 19. The current air volume flow through the condenser 9 is not changed. However, if the condensing pressure continues to rise and exceeds a second upper limit value, the control of the fans or of the air volume flow is taken over directly by the condensing pressure regulator 20. This controller causes the air volume flow to be increased. When the pressure falls below the first upper pressure limit, the heating controller 19 again takes over the control of the boiler and the fans.
  • control device 13 essentially comprises a microcomputer with associated software, data input and data acquisition, measurement value acquisition and conversion and processing, and an output. Furthermore, a 16-digit alphanumeric display and a 10-key data keyboard are arranged on the control device, among other things, for entering setpoints, for querying actual values, outputting messages, and setting a timer.
  • Each refrigeration consumer is usually assigned a solenoid valve that is switched by a thermostat. If the thermostat of the consumer requests cooling capacity and at least one compressor is in operation, the solenoid valve opens. However, if the pressure on the low pressure side is so low that a pressure switch has responded, all compressors are switched off and the solenoid valves are closed and cannot be opened by the thermostats. In this case, it is intended to pulse the solenoid valve, the thermostat of which requires cooling capacity, that is, to switch it on and off alternately. On the one hand, this ensures that the pressure in the suction line rises and, on the other hand, the evaporator is not overfilled with liquid refrigerant, which prevents damage to the compressor due to liquid hammer.

Abstract

1. A method of controlling a compound refrigerating plant comprising a plurality of compressors and at least one fa for the discharge of the heat of liquefication, wherein the air volume flow of the fan or fans is changed in dependence upon the suction air temperature and the refrigerating capacity, characterised in that the suction air temperature Ta and the liquefication pressure Pc are measured and a theoretica value Pc,s of the liquefication pressure is set, which is dpendent upon the air suction temperature.

Description

Die Erfindung betrifft ein Verfahren zur Steuerung einer Verbundkälteanlage mit mehreren Verdichtern und mindestens einem Ventilator für die Abführung der Verflüssigungswärme, bei dem der Luftvolumenstrom des oder der Ventilatoren in Abhängigkeit von der Luftansaugtemperatur und der Kälteleistung verändert wird.The invention relates to a method for controlling a composite refrigeration system with a plurality of compressors and at least one fan for removing the condensing heat, in which the air volume flow of the fan or fans is changed as a function of the air intake temperature and the cooling capacity.

Eine Verbundkälteanlage besteht im wesentlichen aus mehreren Verdichtern mit einer gemeinsamen Saugleitung und einer gemeinsamen Druckleitung, einem Verflüssiger und mehreren Verdampfern sowie Expansionsorganen, die den Verdampfern zugeordnet sind. Dem Verflüssiger sind dabei ein oder mehrere Ventilatoren zugeordnet, die die bei der Verflüssigung des Kältemittels entstehende Wärme abführen. Je nach Kältebedarf ist eine bestimmte Anzahl von Verdichtern sowie eine bestimmte Anzahl von Ventilatoren in Betrieb. Der Betrieb der Verdichter und Ventilatoren erfordert eine hohe Antriebsenergie. Um diese zu senken, werden daher üblicherweise bei Teillastbetrieb Verdichter abgeschaltet, während der oder die Ventilatoren der Verflüssiger weiter bei voller Luftleistung betrieben werden. Damit kann zwar eine gewisse Senkung des Energiebedarfs erreicht werden, doch hat diese Massnahme zur Folge, dass der Anwendungsbereich der Expansionsventile überschritten wird.A composite refrigeration system essentially consists of several compressors with a common suction line and a common pressure line, a condenser and several evaporators as well as expansion elements which are assigned to the evaporators. The condenser is assigned one or more fans which dissipate the heat generated during the liquefaction of the refrigerant. Depending on the cooling requirement, a certain number of compressors and a certain number of fans are in operation. The operation of the compressors and fans requires a high drive energy. To reduce this, compressors are therefore usually switched off during part-load operation, while the condenser fan or fans continue to be operated at full air output. Although this can achieve a certain reduction in energy consumption, the result of this measure is that the application range of the expansion valves is exceeded.

Dies rührt daher, dass die Ventilatoren bei vollem Luftvolumenstrom und Abschaltung einzelner Verdichter eine zu tiefe Absenkung des Verflüssigungsdrucks bewirken können. Die untere Begrenzung des Verflüssigungsdruckes ist durch die verwendeten Expansionsventile sowie das Kältemittel gegeben.This is due to the fact that the fans can cause the condensing pressure to drop too low when the air flow is full and individual compressors are switched off. The lower limit of the condensing pressure is given by the expansion valves used and the refrigerant.

In der DE-A-3 025 439 wird ein Kühlsystem beschrieben, bei dem eines von drei Kühlgebläsen des Verflüssigers in Abhängigkeit von der Temperatur der angesaugten Luft betätigt wird. Die Regelungsmöglichkeit beschränkt sich jedoch auf das Ein- und Ausschalten dieses Gebläses bei einem festen Schwellenwert der Luftansaugtemperatur.DE-A-3 025 439 describes a cooling system in which one of three cooling fans of the condenser is actuated as a function of the temperature of the air drawn in. However, the control option is limited to switching this blower on and off at a fixed threshold air intake temperature.

Die US-A-3 739 596 zeigt ein Kühlsystem, das in Abhängigkeit vom Verflüssigungsdruck gesteuert wird, indem zwei Verflüssigungsventilatoren direkt durch vor dem Verflüssiger angebrachte Druckschalter ein- und ausgeschaltet werden. Eine ähnliche Methode wird in der GB-A-2 067 275 beschrieben. Dort wird bei einem kombinierten Kühl- und Heizsystem vorgeschlagen, Verflüssigerventilatoren in Abhängigkeit vom Verflüssigungsdruck ein- bzw. auszuschalten.US-A-3 739 596 shows a cooling system which is controlled in dependence on the condensing pressure by switching two condensing fans on and off directly by means of pressure switches located in front of the condenser. A similar method is described in GB-A-2 067 275. In the case of a combined cooling and heating system, it is proposed to switch the condenser fans on or off depending on the condensing pressure.

Der Erfindung liegt die Aufgabe zugrunde, das Verhältnis von Kälteleistung der Verdichter zur Leistungsaufnahme der Verdichter und Ventilatoren zu optimieren, also insbesondere bei einer vorgegebenen Kälteleistung eine Minimierung der Gesamtleistungsaufnahme zu erreichen. Dabei soll gleichzeitig der Anwendungsbereich der Expansionsventile gegenüber dem bekannten Verfahren beibehalten und der Verflüssigungsdruck optimiert werden.The object of the invention is to optimize the ratio of the cooling capacity of the compressors to the power consumption of the compressors and fans, that is to say to minimize the total power consumption in particular with a predetermined cooling capacity. At the same time, the area of application of the expansion valves should be maintained compared to the known method and the condensing pressure should be optimized.

Diese Aufgabe wird erfindungsgemäss dadurch gelöst, dass die Luftansaugtemperatur TA und der Verflüssigungsdruck pc gemessen werden und ein von der Luftansaugtemperatur abhängiger Sollwert Pe,s des Verflüssigungsdrucks eingestellt wird.This object is achieved according to the invention in that the air intake temperature T A and the condensing pressure p c are measured and a setpoint Pe , s of the condensing pressure which is dependent on the air intake temperature is set.

Beim erfindungsgemässen Verfahren wird die momentane Kälteleistung indirekt über den Verflüssigungsdruck erfasst. Der gemessene Verflüssigungsdruck wird mit einem Sollwert, in dessen Berechnung die Luftansaugtemperatur und anlagenspezifische Parameter eingehen, verglichen. Je nach Grösse und Vorzeichen der Differenz zwischen gemessenem Verflüssigungsdruck pc und berechneten Verflüssigungssolldruck pss wird der Luftvolumenstrom des oder der Ventilatoren vergrössert oder verkleinert.In the method according to the invention, the instantaneous cooling capacity is recorded indirectly via the condensing pressure. The measured condensing pressure is compared with a setpoint, the calculation of which includes the air intake temperature and system-specific parameters. Depending on the size and sign of the difference between the measured condensing pressure p c and the calculated condensing target pressure pss, the air volume flow of the fan or fans is increased or decreased.

Diese Regelung des Luftvolumenstroms der Verflüssigerventilatoren erlaubt eine besonders günstige Anpassung der Ventilatorleistung an die beiden Parameter Luftansaugtemperatur und Kälteleistung. Zu einer vorgegebenen Anzahl von in Betrieb befindlichen Verdichtern kann die optimale Anzahl von Verflüssigerventilatoren eingeschaltet werden. Im allgemeinen wird mit reduziertem Luftvolumenstrom gearbeitet. Die dadurch bewirkte Einsparung kann für den Antrieb der Verflüssigerventilatoren benötigter Energie macht das erfindungsgemässe Verfahren wirtschaftlich besonders günstig.This regulation of the air volume flow of the condenser fans allows a particularly favorable adaptation of the fan performance to the two parameters air intake temperature and cooling capacity. The optimal number of condenser fans can be switched on for a predetermined number of compressors in operation. In general, a reduced air volume flow is used. The resulting savings can drive the energy required to drive the condenser fans, making the method according to the invention particularly economical.

Die erfindungsgemässe Regelung des Luftvolumenstroms ist insbesondere so vorgesehen, dass bei geringerer Luftansaugtemperatur der Luftvolumenstrom verringert wird. Selbstverständlich beinhaltet dies, dass bei erhöhter Luftansaugtemperatur der Luftvolumenstrom vergrössert wird.The regulation of the air volume flow according to the invention is in particular provided such that the air volume flow is reduced at a lower air intake temperature. Of course, this means that the air volume flow is increased when the air intake temperature is increased.

Bei z. B. geringerer Luftansaugtemperatur, d. h. geringerer Aussentemperatur, wird in einer Anfahrphase zunächst volle Luftleistung gefahren und dann die Luftleistung beispielsweise durch Reduzierung der Drehzahl der Ventilatoren auf 2/3 des ursprünglichen Wertes reduziert. Die damit erzielbaren Einsparungen an Energieaufwand werden weiter unten beschrieben.At z. B. a lower air intake, that is, lower the outside temperature is, driven in a start-first full air output, and then the air power is reduced for example by reducing the speed of the fans to 2/3 of the original value. The energy savings that can be achieved with this are described below.

Bei der Durchführung des erfindungsgemässen Verfahrens ist in Weiterbildung des Erfindungsgedankens ein vorgegebener Bereich des Verflüssigungsdruckes einzuhalten. Dieser Bereich ist einerseits durch einen minimalen Druck begrenzt, der für ein einwandfreies Arbeiten der Expansionsventile notwendig ist, und andererseits durch einen maximalen Druck, der durch die Anwendungsgrenzen der Kältemittelverdichter bestimmt wird. Der einzuhaltende Bereich des Verflüssigungsdruckes hängt überdies von dem jeweils verwendeten Kältemittel ab. Bei den gebräuchlichen Kältemitteln wie R 22 und R 502 liegt der Bereich beispielsweise zwischen ca. 10 bar und ca. 20 bar.When carrying out the method according to the invention, a predetermined range of the condensing pressure must be maintained in a development of the inventive concept. This range is limited on the one hand by a minimum pressure, which is necessary for the expansion valves to work properly, and on the other hand, by a maximum pressure, which is determined by the application limits of the refrigerant compressors. The range of condensing pressure to be observed also depends on the refrigerant used. The range of common refrigerants such as R 22 and R 502 is, for example, between approx. 10 bar and approx. 20 bar.

Es erweist sich als besonders vorteilhaft, den einzustellenden Verflüssigungssolldruck pc,s gemäss der Formel in Patentanspruch 2 festzulegen. Die Parameter A und B hängen von den Eigenschaften des verwendeten Kältemittels und von den Gegebenheiten der Kälteanlage ab.It proves to be particularly advantageous to set the condensing target pressure pc, s to be set according to the formula in claim 2. The parameters A and B depend on the properties of the refrigerant used and on the conditions of the refrigeration system.

Für die Regelung des Luftvolumenstroms bieten sich insbesondere zwei Möglichkeiten an, nämlich Zu- und/oder Abschalten von Ventilatoren oder Änderung der Drehzahl der Ventilatoren. In der Praxis wird dabei wohl in erster Linie die zweitgenannte Möglichkeit wahrgenommen werden, da es sich herausgestellt hat, dass beispielsweise zwei mit halbem Luftvolumenstrom betriebene Ventilatoren weniger Antriebsenergie benötigen als ein mit vollem Luftvolumenstrom betriebener Ventilator.There are two options for regulating the air volume flow, namely switching fans on and / or off or changing the speed of the fans. In practice, the second option mentioned will probably be used primarily, since it has been found that, for example, two fans operated at half the air volume flow require less drive energy than one fan operated at full air volume flow.

Überdies besteht auch die Möglichkeit, den Luftvolumenstrom durch Verstellung von Drosselklappen zu verändern.In addition, there is also the possibility of changing the air volume flow by adjusting throttle valves.

Bei dem bislang beschriebenen Verfahren findet in Verbindung mit der Verbundkälteanlage keine Wärmerückgewinnung statt. In Weiterbildung des erfindungsgemässen Verfahrens ist jedoch auch die Steuerung einer Verbundkälteanlage vorgesehen, bei der eine zusätzliche Wärmerückgewinnung für Raumheizung und Brauchwasser-erwärmung vorgesehen ist. In diesem Falle wird erfindungsgemäss der Luftvolumenstrom zusätzlich in Abhängigkeit von der Warmwasservorlauftemperatur und/oder der Raumtemperatur geregelt.In the method described so far, there is no heat recovery in connection with the composite refrigeration system. In a further development of the method according to the invention, however, the control of a composite refrigeration system is also provided, in which additional heat recovery is provided for space heating and domestic water heating. In this case, according to the invention, the air volume flow is additionally regulated as a function of the hot water supply temperature and / or the room temperature.

Zur Energieeinsparung durch Abwärmenutzung können entsprechend den örtlichen Gegebenheiten und den Eigenschaften einer vorhandenen Kälteanlage überdies die folgenden Wärmerückgewinnungssysteme installiert werden:

  • - Vorerhitzer in Lüftungsgeräten, die von dem warmen Druckgas durchströmt werden und im Heizbetrieb als Verflüssiger arbeiten.
  • - Den luftgekühlten Verflüssigern vorgeschaltete wassergekühlte Apparate, die ihre Wärme an die Vorheizregister von Lüftungsgeräten abgeben.
  • - Wärmepumpen, die bei Verbundanlagen durch einen Verdampfer-Verflüssiger die Verflüssigungswärme aufnehmen und sie mit einem hohen Temperaturniveau, mittels Wasser als Trägermedium, direkt in den Heizwasserrücklauf der Heizanlage einspeisen (Vorlauftemperatur ca. 60°C).
To save energy by using waste heat, the following heat recovery systems can also be installed depending on the local conditions and the properties of an existing refrigeration system:
  • - Preheater in ventilation units through which the warm compressed gas flows and which work as a condenser in heating mode.
  • - Water-cooled devices connected upstream of the air-cooled condensers, which emit their heat to the preheating register of ventilation units.
  • - Heat pumps that absorb the heat of condensation in composite systems through an evaporator-condenser and feed them directly into the heating water return of the heating system at a high temperature level using water as the carrier medium (flow temperature approx. 60 ° C).

In einer zweckmässigen Weiterbildung des erfindungsgemässen Verfahrens wird bei sinkendem Kältebedarf der Verdampfungsdruck des Kältemittels erhöht. Wenn die Umgebungstemperatur und damit auch der Kältebedarf sinkt, wird die Verdampfungstemperatur und damit auch der Verdampfungsdruck des Kältemittels erhöht. Durch die geringere Druckdifferenz zwischen Verdampfungs- und Verflüssigungsdruck muss weniger Energie zum Verdichten aufgebracht werden.In an expedient development of the method according to the invention, the evaporation pressure of the refrigerant is increased when the cooling requirement drops. If the ambient temperature and thus the cooling requirement decrease, the evaporation temperature and thus the evaporation pressure of the refrigerant is increased. The lower pressure difference between evaporation and condensing pressure means that less energy has to be applied for compression.

Das erfindungsgemässe Verfahren ist anwendbar auf alle Verbundkälteanlagen, so z. B. für gekühlte und tiefgekühlte Verkaufsmöbel in Supermärkten, für Schlachthöfe, Kühlhäuser oder verfahrenstechnische Anlagen.The inventive method is applicable to all composite refrigeration systems, such. B. for chilled and frozen sales furniture in supermarkets, for slaughterhouses, cold stores or process engineering systems.

Die Erfindung sei im folgenden anhand eines in Figur 1 schematisch dargestellten Ausführungsbeispiels näher erläutert.The invention is explained in more detail below on the basis of an exemplary embodiment shown schematically in FIG.

In dem Ausführungsbeispiel sind vier parallelgeschaltete Verdichter 1a, 1b, 1c und 1d über eine gemeinsame Saugleitung 4, mehrere Verdampfer 5 sowie Expansionsventile 6 an einem Sammelbehälter 7 angeschlossen. Der Einfachheit halber sind nur ein Verdampfer und ein Expansionsventil dargestellt, doch sind in der Praxis meist mehrere Verdampfer und Expansionsventile parallel geschaltet. In dem Sammelbehälter wird flüssiges Kältemittel eingespeichert und über die Expansionsventile 6 den Verdampfern zugeleitet. Das Kältemittelsauggas in Leitung 4 wird sodann gleichmässig auf die einzelnen Verdichter der Verbundanlage verteilt und von diesen angesaugt. Verdichteter Kältemitteldampf wird sodann in eine gemeinsame Druckleitung 8 geleitet und zu einem Verflüssiger 9 geführt, in dem die Dämpfe kondensiert und in flüssiger Form über Leitung 10 in den Sammelbehälter 7 abgegeben werden.In the exemplary embodiment, four compressors 1a, 1b, 1c and 1d connected in parallel are connected to a collecting container 7 via a common suction line 4, a plurality of evaporators 5 and expansion valves 6. For the sake of simplicity, only one evaporator and one expansion valve are shown, but in practice several evaporators and expansion valves are usually connected in parallel. Liquid refrigerant is stored in the collecting container and fed to the evaporators via the expansion valves 6. The refrigerant suction gas in line 4 is then evenly distributed to the individual compressors of the composite system and sucked in by them. Compressed refrigerant vapor is then passed into a common pressure line 8 and to a condenser 9, in which the vapors are condensed and released in liquid form via line 10 into the collecting container 7.

Der Verflüssiger 9 ist mit Ventilatoren 11, 12 ausgestattet, die mit einem Steuergerät 13 verbunden sind. Der von den Ventilatoren umgewälzte Luftvolumenstrom wird über den Verflüssiger geleitet und führt dabei die Verflüssigungswärme ab, so dass in dem Verflüssiger die Kältemittelkondensation stattfinden kann. An das Steuergerät 13 ist ein Temperaturfühler 14 angeschlossen, der die Temperatur im Luftansaugkanal des Verflüssigers erfasst. Dem Verflüssiger ist ausserdem ein Drucktransmitter 20 zugeordnet, der ebenfalls an das Steuergerät 13 angeschlossen ist.The condenser 9 is equipped with fans 11, 12 which are connected to a control unit 13. The air volume flow circulated by the fans is conducted via the condenser and removes the heat of condensation, so that the refrigerant condensation can take place in the condenser. A temperature sensor 14 is connected to the control unit 13 and detects the temperature in the air intake duct of the condenser. The condenser is also assigned a pressure transmitter 20, which is also connected to the control unit 13.

Zur Wärmerückgewinnung ist in Leitung 8 überdies ein Verflüssiger 15 vorgesehen, in dem die Verflüssigungswärme zur Brauchwasser-Erwärmung und/oder zur Raumheizung genutzt werden kann. Über Leitung 16 wird beispielsweise Wasser aus dem Raumheizungskreislauf herangeführt und im Verflüssiger 15 angewärmt. Reicht die Verflüssigungswärme nicht aus, so kann zusätzlich ein Heizkessel 17 eingeschaltet werden. Über eine Pumpe 18 wird das Warmwasser zu den Wärmeverbrauchern zurückgeführt. Dem Heizkessel ist ein Heizungsregler 19 zugeordnet, der mit dem Steuergerät 13 verbunden ist.For heat recovery, a condenser 15 is also provided in line 8, in which the condensation heat can be used for heating domestic water and / or for space heating. For example, water from the space heating circuit is supplied via line 16 and heated in the condenser 15. If the heat of liquefaction is insufficient, a boiler 17 can also be switched on. The hot water is returned to the heat consumers via a pump 18. A heating controller 19, which is connected to the control unit 13, is assigned to the boiler.

Die mit dem Verfahren gemäss dem vorstehend geschilderten Ausführungsbeispiel erzielbare Energieeinsparung ist aus den Tabellen Punkt 2a) bis d) der Anlage zu entnehmen. Das Verfahren wird zunächst ohne Wärmerückgewinnung beschrieben, so dass der Verflüssiger 15 mit dem daran angeschlossenen Kreislauf unbeachtet bleibt. Der Temperaturfühler 14 erfasst die Temperatur der Luft im Ansaugkanal des Verflüssigers und verschiebt den Sollwert pss. Die Berechnung der Sollwertverschiebung erfolgt im Steuergerät 13 nach der Formel

  • pc,s = A - TA + B
  • A = Parameter in bar/°C
  • B = Parameter in bar
  • TA = Aussentemperatur in °C
  • pc = Verflüssigungsdruck in bar.
The energy savings which can be achieved with the method according to the exemplary embodiment described above can be seen from the tables point 2a) to d) of the system. The process is first described without heat recovery, so that the condenser 15 with the circuit connected to it is ignored. The temperature sensor 14 detects the temperature of the air in the intake duct of the condenser and shifts the setpoint pss. The setpoint shift is calculated in control unit 13 using the formula
  • p c, s = A - T A + B
  • A = parameter in bar / ° C
  • B = parameter in bar
  • T A = outside temperature in ° C
  • p c = condensing pressure in bar.

Die Parameter A und B dienen der Anpassung an das jeweilige Kältemittel und an anlagenspezifische Gegebenheiten.Parameters A and B are used to adapt to the respective refrigerant and system-specific conditions.

Bei sinkender Umgebungstemperatur sinkt der Kältebedarf der Kälteverbraucher. Eine Anpassung der Kälteleistung an diesen Bedarf kann durch Anheben der Verdampfungstemperatur (Erhöhen des Verdampfungsdruckes) des Kältemittels geschehen. Dadurch wird die von den Verdichtern zu überwindende Druckdifferenz verringert, was zu einer entsprechenden Energieeinsparung führt.When the ambient temperature drops, the cooling consumers' cooling requirements decrease. The refrigerating capacity can be adapted to this requirement by raising the evaporating temperature (increasing the evaporating pressure) of the refrigerant. As a result, the pressure difference to be overcome by the compressors is reduced, which leads to a corresponding energy saving.

Mit Wärmerückgewinnung verläuft das erfindungsgemässe Verfahren etwas anders. Die Schaltung der Ventilatoren erfolgt in diesem Falle in Abhängigkeit des Heizungsreglers 19, der die Wasservorlauftemperatur erfasst und dessen Sollwert von der Aussentemperatur geschoben wird. Reicht dabei die Verflüssigungswärme im Verflüssiger 15 nicht aus, um die erforderliche Anwärmung des Wassers zu gewährleisten, so wird zusätzlich der Heizkessel 17 eingeschaltet. Steigt während der Wärmerückgewinnung der Verflüssigungsdruck auf einen einstellbaren ersten oberen Grenzwert an, wird der Heizkessel 17 weiterhin über den Heizungsregler 19 gesteuert. Dabei wird der momentane Luftvolumenstrom durch den Verflüssiger 9 nicht verändert. Steigt der Verflüssigungsdruck aber weiter an und überschreitet einen zweiten oberen Grenzwert, so wird die Steuerung der Ventilatoren bzw. des Luftvolumenstroms direkt von dem Verflüssigungsdruckregler 20 übernommen. Dieser Regler veranlasst, dass der Luftvolumenstrom erhöht wird. Beim Unterschreiten des ersten oberen Druckgrenzwertes übernimmt der Heizungsregler 19 wieder die Steuerung des Heizkessels und der Ventilatoren.The process according to the invention proceeds somewhat differently with heat recovery. In this case, the fans are switched as a function of the heating controller 19, which detects the water flow temperature and whose setpoint is shifted from the outside temperature. If the heat of condensation in the condenser 15 is not sufficient to ensure the necessary heating of the water, the boiler 17 is additionally switched on. If the condensing pressure rises to an adjustable first upper limit value during heat recovery, the boiler 17 is still controlled by the heating controller 19. The current air volume flow through the condenser 9 is not changed. However, if the condensing pressure continues to rise and exceeds a second upper limit value, the control of the fans or of the air volume flow is taken over directly by the condensing pressure regulator 20. This controller causes the air volume flow to be increased. When the pressure falls below the first upper pressure limit, the heating controller 19 again takes over the control of the boiler and the fans.

Das Steuergerät 13 umfasst zur Durchführung des erfindungsgemässen Verfahrens im wesentlichen einen Mikrocomputer mit zugehöriger Software, eine Dateneingabe und -erfassung, Messwerterfassung und -umwandlung sowie -verarbeitung und eine Ausgabe. Ferner sind auf dem Steuergerät eine bevorzugt 16-stellige alphanumerische Anzeige sowie eine 10er Datentastatur unter anderem zur Eingabe von Sollwerten, zur Abfrage von Istwerten, Ausgabe von Meldungen, Einstellen einer Zeituhr angeordnet.To carry out the method according to the invention, the control device 13 essentially comprises a microcomputer with associated software, data input and data acquisition, measurement value acquisition and conversion and processing, and an output. Furthermore, a 16-digit alphanumeric display and a 10-key data keyboard are arranged on the control device, among other things, for entering setpoints, for querying actual values, outputting messages, and setting a timer.

Mit diesem Steuergerät ist eine optimale Anpassung der erzeugten Kälteleistung an den jeweiligen Kältebedarf der Verbraucher möglich, wobei es prinzipielles Ziel ist, den Verflüssigungsdruck so niedrig wie möglich zu halten, um den Energiebedarf zu minimieren. Dieses trifft sowohl für eine Verbundkälteanlage mit als auch ohne Wärmerückgewinnung zu.With this control unit, an optimal adaptation of the generated cooling capacity to the respective cooling requirement of the consumer is possible, whereby the basic goal is to keep the condensing pressure as low as possible in order to minimize the energy requirement. This applies both to a composite refrigeration system with and without heat recovery.

Das Steuergerät beinhaltet die folgenden Möglichkeiten:

  • 1. Integrierende Analog-Messwerterfassung.
  • 2. Quarzgesteuerte Kalenderuhr.
  • 3. Datensicherung bei Netzausfall bis zu 14 Tagen.
  • 4. Ausgaben der aktualisierten Istwerte während des Betriebes auf der alphanumerischen Anzeige.
  • 5. Messwertüberwachung.
  • 6. Eingang für Heizungregler.
  • 7. Automatische Umschaltung von Kühl- in den Wärmerückgewinnungsbetrieb und umgekehrt.
  • 8. Steuerung von Kältemittelverdichtern und zusätzlich eine Leistungsstufe pro Verdichter in Abhängigkeit vom Niederdruck.
  • 9. Anzahl der Kältemittelverdichter und Leistungsstufen wählbar.
  • 10. Regelung und Überwachung der Öltemperatur.
  • 11. Steuerung der Kältemittelverdichterzusatzventilatoren in Abhängigkeit der Druckrohrtemperatur.
  • 12. Überwachung der Temperatur in der Druckleitung.
  • 13. Überwachung der Wicklungstemperatur der
  • Antriebsmotoren der Kältemittelverdichter. 14. Öldrucküberwachung der Kältemittelverdichter.
  • 15. Steuerung der Verflüssigerventilatoren im Kühlbetrieb sowie eine zusätzliche Schaltstufe für einen weiteren Wärmeerzeuger bei der Wärmerückgewinnung.
  • 16. Anzahl der Stufen der Verflüssigerventilatoren ist wählbar.
  • 17. Keilriemenüberwachung bei Betrieb der Verflüssigerventilatoren mit Keilriemen.
  • 18. Drucküberwachung in der Anlage.
  • 19. Sollwertschiebung von Verflüssigungs- und Verdampfungsdruck.
  • 20. Zwei Eingänge für Lastabwurf.
  • 21. Störungen werden mit Datum und Uhrzeit gespeichert.
  • 22. Automatische Grundlastumschaltung mit wählbarer Umschaltzeit.
  • 23. Alle Daten können auf einem Drucker ausgegeben werden (immer mit Datum und Uhrzeit versehen).
  • 24. Saugdruckanhebung.
  • 25. Pulsen.
The control unit includes the following options:
  • 1. Integrating analog measured value acquisition.
  • 2. Quartz controlled calendar clock.
  • 3. Data backup in the event of a power failure for up to 14 days.
  • 4. Output of the updated actual values during operation on the alphanumeric display.
  • 5. Measured value monitoring.
  • 6. Input for heating controller.
  • 7. Automatic switching from cooling to heat recovery mode and vice versa.
  • 8. Control of refrigerant compressors and an additional power level per compressor depending on the low pressure.
  • 9. Number of refrigerant compressors and power levels selectable.
  • 10. Control and monitoring of the oil temperature.
  • 11. Control of the additional refrigerant compressor fans depending on the pressure pipe temperature.
  • 12. Monitoring the temperature in the pressure line.
  • 13. Monitoring the winding temperature of the
  • Drive motors of the refrigerant compressors. 14. Oil pressure monitoring of the refrigerant compressors.
  • 15. Control of the condenser fans in cooling mode and an additional switching stage for a further heat generator in the heat recovery.
  • 16. The number of stages of the condenser fans can be selected.
  • 17. V-belt monitoring when operating the condenser fans with V-belts.
  • 18. Pressure monitoring in the system.
  • 19. Setpoint shift of condensing and evaporation pressure.
  • 20. Two inputs for load shedding.
  • 21. Faults are saved with the date and time.
  • 22. Automatic base load switchover with selectable switchover time.
  • 23. All data can be output on a printer (always provided with the date and time).
  • 24. Suction pressure increase.
  • 25. Pulse.

Jedem Kälteverbraucher ist üblicherweise ein Magnetventil zugeordnet, das von einem Thermostaten geschaltet wird. Falls der Thermostat des Verbrauchers Kälteleistung anfordert, und mindestens ein Verdichter in Betrieb ist, öffnet das Magnetventil. Ist nun aber der Druck auf der Niederdruckseite so tief, dass ein Druckwächter angesprochen hat, sind alle Verdichter weggeschaltet und die Magnetventile geschlossen und durch die Thermostate nicht zu öffnen. Für diesen Fall ist vorgesehen, das Magnetventil, dessen Thermostat Kälteleistung anfordert, zu pulsen, also im Wechsel ein- und auszuschalten. Damit wird einerseits erreicht, dass der Druck in der Saugleitung ansteigt und andererseits wird eine Überfüllung der Verdampfer mit flüssigem Kältemittel verhindert, wodurch Verdichterschäden durch Flüssigkeitsschläge vermieden werden.Each refrigeration consumer is usually assigned a solenoid valve that is switched by a thermostat. If the thermostat of the consumer requests cooling capacity and at least one compressor is in operation, the solenoid valve opens. However, if the pressure on the low pressure side is so low that a pressure switch has responded, all compressors are switched off and the solenoid valves are closed and cannot be opened by the thermostats. In this case, it is intended to pulse the solenoid valve, the thermostat of which requires cooling capacity, that is, to switch it on and off alternately. On the one hand, this ensures that the pressure in the suction line rises and, on the other hand, the evaporator is not overfilled with liquid refrigerant, which prevents damage to the compressor due to liquid hammer.

Leistungsbedarfswerte von Verbundkälteanlagen mit 4 KältemittelverdichternPerformance requirements of composite refrigeration systems with 4 refrigerant compressors

  • 1. Lufteintrittstemperatur in Verflüssiger entsprechend Auslegungsbedingungen.
    • a) Die Leistungswerte einer typischen Verbundkälteanlage für Supermärkte bei Auslegungsbedingungen ergeben sich wie folgt (ohne Kälteverbraucher wie Kühlmöbel, Kühlräume etc.):
      • - Kälteleistung 100% - Leistungsbedarf Kältemittelverdichter ca. 78%
      • - Leistungsbedarf Verflüssigerventilatoren ca. 20%
      • - Leistungsbedarf Ventilatoren für Verdichterkühlung ca. 1%
      • - Leistungsbedarf für Kurbelgehäuseheizung ca. 1%
      • - Gesamtleistungsbedarf ca. 100%
    • b) Die Leistungswerte dieser Verbundkälteanlage bei ca. 50% Kältebedarf (2 Kältemittelverdichter in Betrieb) und voller Leistung der Verflüssigungsventilatoren betragen:
      • - Kälteleistung ca. 56%
      • - Leistungsbedarf Kältemittelverdichter ca. 40%
      • - Leistungsbedarf Verflüssigungsventilatoren ca. 20%
      • - Leistungsbedarf Ventilatoren für Verdichterkühlung ca. 0,5%
      • - Leistungsbedarf Kurbelgehäuseheizung ca. 0,5%
      • - Gesamtleistungsbedarf ca. 61 %
    • c) Bei gleichen Bedingungen wie Punkt 1b) aber Reduzierung der Drehzahl der Verflüssigerventilatoren auf
      Figure imgb0001
      der Nenndrehzahl (Reduzierung des Luftvolumenstromes auf ca.
      Figure imgb0002
       ergeben sich nachstehende Werte:
      • - Kälteleistung ca. 53%
      • - Leistungsbedarf Kältemittelverdichter ca. 39,5%
      • - Leistungsbedarf Verflüssigerventilatoren ca. 7%
      • - Leistungsbedarf Ventilatoren für Verdichterkühlung ca. 0,5%
      • - Leistungsbedarf Kurbelgehäuseheizung ca. 0,5%
      • - Gesamtleistungsbedarf ca. 47,5%
    1. Air inlet temperature in the condenser according to the design conditions.
    • a) The performance values of a typical composite refrigeration system for supermarkets under design conditions are as follows (without cold consumers such as refrigeration units, cold rooms, etc.):
      • - Refrigeration capacity 100% - Refrigerant compressor capacity requirement approx. 78%
      • - Power requirement condenser fans approx. 20%
      • - Power requirement fans for compressor cooling approx. 1%
      • - Power requirement for crankcase heating approx. 1%
      • - total power requirement approx. 100%
    • b) The performance values of this composite refrigeration system with approx. 50% cooling requirement (2 refrigerant compressors in operation) and full performance of the condensing fans are:
      • - cooling capacity approx. 56%
      • - Power requirement refrigerant compressor approx. 40%
      • - Power requirement condensing fans approx. 20%
      • - Power requirement fans for compressor cooling approx. 0.5%
      • - Power requirement crankcase heating approx. 0.5%
      • - total power requirement approx. 61%
    • c) Under the same conditions as point 1b) but the speed of the condenser fans is reduced to
      Figure imgb0001
       the nominal speed (reduction of the air volume flow to approx.
      Figure imgb0002
       the following values result:
      • - cooling capacity approx. 53%
      • - Refrigerant compressor power requirement approx. 39.5%
      • - Power requirement condenser fans approx. 7%
      • - Power requirement fans for compressor cooling approx. 0.5%
      • - Power requirement crankcase heating approx. 0.5%
      • - total power requirement approx. 47.5%
  • 2. Lufteintrittstemperatur in Verflüssiger um 10 K abgesenkt.
    • a) Bei den sonstigen Bedingungen wie Punkt 1a ergeben sich folgende Werte:
      • - Kälteleistung ca. 122%
      • - Leistungsbedarf Kältemittelverdichter ca. 81%
      • - Leistungsbedarf Verflüssigungsventilatoren ca. 20%
      • - Leistungsbedarf Ventilatoren für Verdichterkühlung ca. 1%
      • - Leistungsbedarf Kurbelgehäuseheizung ca. 1%
      • - Gesamtleistungsbedarf ca. 103%
    • b) Bei den sonstigen Bedingungen wie Punkt 2a) aber Reduzierung der Drehzahl der Verflüssigerventilatoren auf 2/3 der Nenndrehzahl ergeben sich für
      • - Kälteleistung ca. 112%
      • - Leistungsbedarf Kältemittelverdichter ca. 80%
      • - Leistungsbedarf Verflüssigerventilatoren ca. 7%
      • - Leistungsbedarf Ventilatoren für Verdichterkühlung ca. 1%
      • - Leistungsbedarf Kurbelgehäuseheizung ca. 1%
      • - Gesamtleistungsbedarf ca. 89%
    • c) Bedingungen wie Punkt 2a) jedoch mit 50% Kältebedarf (2 Kältemittelverdichter in Betrieb) und volle Drehzahl der Verflüssigerventilatoren.
      • - Kälteleistung ca. 67%
      • - Leistungsbedarf Kältemittelverdichter ca. 41 %
      • - Leistungsbedarf Verflüssigerventilatoren ca. 20%
      • - Leistungsbedarf Ventilatoren für Verdichterkühlung ca. 0,5%
      • - Leistungsbedarf Kurbelgehäuseheizung ca. 0,5%
      • - Gesamtleistungsbedarf ca. 62%
    • d) Bedingungen wie Punkt 2c jedoch mit Reduzierung der Verflüssigerventilatoren auf
      Figure imgb0003
       ihrer Nenndrehzahl.
      • - Kälteleistung ca. 62%
      • - Leistungsbedarf Kältemittelverdichter ca. 40,5%
      • - Leistungsbedarf Verflüssigerventilatoren ca. 7%
      • - Leistungsbedarf Ventilatoren für Verdichterkühlung ca. 0,5%
      • - Leistungsbedarf Kurbelgehäuseheizung ca. 0,5%
      • - Gesamtleistungsbedarf ca. 48,5%
    2. Air inlet temperature in condenser reduced by 10 K.
    • a) With the other conditions like point 1a the following values result:
      • - cooling capacity approx. 122%
      • - Power requirement refrigerant compressor approx. 81%
      • - Power requirement condensing fans approx. 20%
      • - Power requirement fans for compressor cooling approx. 1%
      • - Power requirement crankcase heating approx. 1%
      • - total power requirement approx. 103%
    • b) The other conditions such as point 2a) but reduce the speed of condenser fans to 2/3 of the nominal rotational speed obtained for
      • - cooling capacity approx. 112%
      • - Power requirement refrigerant compressor approx. 80%
      • - Power requirement condenser fans approx. 7%
      • - Power requirement fans for compressor cooling approx. 1%
      • - Power requirement crankcase heating approx. 1%
      • - total power requirement approx. 89%
    • c) Conditions as point 2a) but with 50% cooling requirement (2 refrigerant compressors in operation) and full speed of the condenser fans.
      • - cooling capacity approx. 67%
      • - Power requirement refrigerant compressor approx. 41%
      • - Power requirement condenser fans approx. 20%
      • - Power requirement fans for compressor cooling approx. 0.5%
      • - Power requirement crankcase heating approx. 0.5%
      • - total power requirement approx. 62%
    • d) Conditions like point 2c but with reduction of the condenser fans to
      Figure imgb0003
       their nominal speed.
      • - cooling capacity approx. 62%
      • - Power requirement refrigerant compressor approx.40.5%
      • - Power requirement condenser fans approx. 7%
      • - Power requirement fans for compressor cooling approx. 0.5%
      • - Power requirement crankcase heating approx. 0.5%
      • - total power requirement approx. 48.5%

Claims (7)

1. A method of controlling a compound refrigerating plant comprising a plurality of compressors and at least one fan for the discharge of the heat of liquefication, wherein the air volume flow of the fan or fans is changed in dependence upon the suction air temperature and the refrigerating capacity, characterised in that the suction air temperature TA and the liquefication pressure Pe are measured and a theoretical value pc,s of the liquefication pressure is set, which is dependent upon the air suction temperature.
2. A method as claimed in Claim 1, characterised in that the theoretical liquefication pressure pc,s which is to be set is defined in accordance with the formula:
Figure imgb0005
where
A = parameter in bar/°C.
B = parameter in bar,
TA = air suction temperature.
3. A method as claimed in Claim 1, characterised in that the air volume flow is regulated by switching fans on and/or off.
4. A method as claimed in Claim 1, characterised in that the air volume flow is regulated by changing the speed of rotation of the fans.
5. A method as claimed in one of Claims 1 to 4, characterised in that with a lower air suction temperature the air volume flow is reduced.
6. A method of controlling a compound refrigerating plant as claimed in Claim 1, wherein heat recovery for room heating and domestic water heating is additionally provided, characterised in that the air volume flow is additionally regulated in dependence upon the hot water forward flow temperature and/or the room temperature.
7. A method as claimed in one of Claims 1 to 6, characterised in that with a reducing refrigerating requirement, the vaporisation pressure of the refrigerating agent is increased.
EP84115860A 1984-02-17 1984-12-19 Control method for a compound refrigeration plant Expired EP0152608B1 (en)

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DE3405810 1984-02-17

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DE3405810A1 (en) 1985-08-22
DE3475564D1 (en) 1989-01-12
ATE39180T1 (en) 1988-12-15
EP0152608A3 (en) 1986-04-09
EP0152608A2 (en) 1985-08-28

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