WO1989007741A1 - Arrangement for continuously controlling the capacity of a refrigerating machine - Google Patents

Arrangement for continuously controlling the capacity of a refrigerating machine Download PDF

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Publication number
WO1989007741A1
WO1989007741A1 PCT/CH1988/000036 CH8800036W WO8907741A1 WO 1989007741 A1 WO1989007741 A1 WO 1989007741A1 CH 8800036 W CH8800036 W CH 8800036W WO 8907741 A1 WO8907741 A1 WO 8907741A1
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Prior art keywords
control
arrangement
control valve
suction
valve
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PCT/CH1988/000036
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German (de)
French (fr)
Inventor
Andres Josef Hegglin
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Andres Josef Hegglin
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Priority to PCT/CH1988/000036 priority Critical patent/WO1989007741A1/en
Publication of WO1989007741A1 publication Critical patent/WO1989007741A1/en

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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
    • 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
    • F25B41/00—Fluid-circulation arrangements
    • F25B41/30—Expansion means; Dispositions thereof
    • F25B41/31—Expansion valves
    • F25B41/34—Expansion valves with the valve member being actuated by electric means, e.g. by piezoelectric actuators
    • 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
    • F25B2600/00—Control issues
    • F25B2600/21—Refrigerant outlet evaporator temperature
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Definitions

  • the invention relates to a device for the continuous control of the cooling capacity of refrigeration machines of the type assumed in the preamble of claim 1.
  • the control intervention takes place directly in the refrigerant flow.
  • Suction throttle controls have a control valve in the suction line between the evaporator and the compressor. If the cooling requirement drops, they throttle the circulating refrigerant flow by closing the control valve. This reduces the cooling capacity of the chiller. In order to ensure the minimum gas flow to the compressor, either a bybass must be provided above the control valve or the necessary quantity of replacement gas must be made available by adding hot gas and spraying it into the suction line.
  • suction throttle controls have significant disadvantages:
  • the suction throttle valve In order to achieve good controllability, the suction throttle valve must have the greatest possible throttle resistance. This additional resistance has to be overcome by higher compressor performance and work.
  • the throttling generated by the control valve leads to a decrease in gas velocity in the suction line and can thereby impair the del return flow in the compressions.
  • Hot gas bypass control is via a control valve in the short-circuit line between the pressure side after the compressor and the pressure side.
  • the short circuit in front of the compressor opens on the suction side, while in the case of indirect hot gas bypass control the short circuit between the expansion valve and evaporator opens into the liquid line.
  • a post-injection valve is required for direct hot gas admixture.
  • the free Placement of the evaporator in relation to the compressor is restricted.
  • an electronically operated control valve (item 1, fig 1) is proposed, which can be positioned using a large number of control variables. It primarily regulates the cooling capacity as required.
  • the overheating is not regulated to a constant ratio, but varies depending on the load.
  • the performance of the refrigeration machine is optimized by filling the evaporator with refrigerant until an electronic differential controller throttles the refrigerant supply when the adjustable, minimal overheating is undershot.
  • the controller As a function of the deviation between the controlled variable x and the reference variable w, the controller (RR fig 1) generates an actuating signal yR which positions the valve. Increasing deviations (x - w) lead to the control valve opening. As a result, more refrigerant flows and the cooling capacity increases corresponding. If the cooling requirement drops, the control valve reduces the refrigerant flow. If the valve closes, the compressor (item 5. fig 1) would empty the evaporator and be switched off by the low pressure pressostat (NP fig 2). In order to ensure the minimum amount of gas required for the compressor in part-load operation, a short-circuit line (item 5. fig 2) is provided between the high and low pressure sides from the compressor to the evaporator.
  • This short-circuit line is tightly closed by an automatic hot gas bypass valve (item 7. fig 2) above a certain suction pressure ps.
  • an automatic hot gas bypass valve (item 7. fig 2) above a certain suction pressure ps.
  • the suction pressure ps falls below a value mechanically set on the hot gas bypass valve, it opens the short-circuit line.
  • the suction pressure ps thus stabilizes at the set pressure level, regardless of the control valve position.
  • a minimum temperature difference ⁇ t (ts - to) is maintained by a further control circuit consisting of the temperature sensors to (evaporation temperature) and ts (suction gas temperature) (to, ts fig 2) .
  • This difference is continuously compared with the setpoint ⁇ tw and converted into a control signal y ⁇ t by the differential controller (DR fig 2).
  • the control signal increases with increasing temperature difference ⁇ t (also called overheating) and weakens accordingly with decreasing overheating.
  • the control valve then throttles the refrigerant supply into the evaporator until the desired minimal overheating is reached.
  • the overheating usually drops at full cooling capacity because the control valve (item 1.
  • fig 1 opens fully.
  • the cooling capacity of a refrigeration machine can be significantly optimized through precise, brief overheating control. The scarcer the overheating is chosen, the better the filling degree of evaporator. The cooling capacity emitted by the evaporator increases accordingly.
  • a logic module (LM fig 2) continuously compares the control signals of the power control yR and the superheat control y ⁇ t. It always selects the smaller one between the two steep signals. If the control signal yR is greater than or equal to y ⁇ t, y ⁇ t is fed to the control valve (item 1. fig 1.2.3). As a rule, the maximum load case is then available.
  • the superheating controller thus acts exclusively on the control valve. If, on the other hand, the control signals change to yR less than y ⁇ t, the logic module (LM fig 2,3) selects the control signal yR. Then there is partial load, the evaporator fill level drops and the overheating increases. The control signal y ⁇ t thus increases, while the control signal yR weakens when the cooling requirement drops. The control valve then begins to throttle the refrigerant flow. As a result, the evaporation and suction pressure ps also decrease. If the evaporation pressure falls below a certain fixed ps, the automatic hot gas bypass valve opens and supplies the compressor with the necessary replacement gas.
  • a tightly closing "open-to" valve can be provided between the pressure side and the hot gas bypass. It blocks the flow in the short-circuit line during pump-down.
  • the sensor signal ts (fig 3) can be used as part of an additional control loop for monitoring them.
  • the suction gas regulator (RS fig 3) generates an actuating signal yS that is immediate and unconditional on the The control valve acts as soon as ts rises above the setpoint ws. Through its opening, liquid refrigerant flows into the evaporator and cools the inflowing hot gas until the suction gas temperature again corresponds to the target temperature.

Abstract

Arrangement for continuously controlling the refrigerating capacity of a refrigerating machine, comprising a closed refrigeration cycle with evaporator (3), compressor (5) and condenser (2). Instead of an expansion valve, an electronically controlled control valve is proposed. Control parameters of the medium to be cooled are compared with predetermined target values in a control device (RR). The control valve is set in function of the difference between control parameter and target value. The valve setting governs the flow of refrigerant and hence the corresponding refrigerating capacity. To achieve optimal filling of the evaporator at full load, an additional control device (DR) monitors the minimal difference between suction gas temperature and evaporating temperature. To prevent an excessive drop in evaporating pressure under partial load, an automatic hot gas bypass control device (7) arranged between the high-pressure line and the evaporator feeds substitute gas to the supplier immediately the suction pressure falls below a given value. To protect the compressor from excessively high temperatures, the suction gas control device (RS) opens the control valve until the suction gas temperature falls to the permissible value.

Description

Anordnung zur stetigen Leistung sregelung von kältemaschinen Arrangement for constant power control of chillers
Die Erfindung betrifft eine Einrichtung zur kontinuierlichen Regelung der Kühlleistung von Kältemaschinen der im Oberbegriff des Patentanspruch 1 unterstellten Art. Der Regeleingriff erfolgt direkt im Kältemittelfluss.The invention relates to a device for the continuous control of the cooling capacity of refrigeration machines of the type assumed in the preamble of claim 1. The control intervention takes place directly in the refrigerant flow.
Im Gegensatz zu schaltenden Regeleinrichtungen führt die kontinuierliche Regelung zu einem steten, ausgeglichenen Verlauf der Regelgrössen (Temperatur, Feuchte usf). Die kontinuierliche, bzw. stetige Leistungsregelung findet deshalb dort Anwendung, wo Führungsgrössen (Sollwerte) genau eingehalten werden müssen. Typische Anwendungen dieser Regelart finden sich in Human-Klimaanlagen mit starkwechselnden Kühllasten, in Klimakammern, in Transport-, Lager- und Verkaufseinrichtungen für Kühl- und Gefriergüter. Zwei Verfahren zur stetigen Leistungsregelung sind bekannt:In contrast to switching control devices, continuous control leads to a constant, balanced course of the controlled variables (temperature, humidity, etc.). The continuous or steady power control is therefore used where reference variables (setpoints) must be strictly observed. Typical applications of this type of control can be found in human air conditioning systems with rapidly changing cooling loads, in climatic chambers, in transport, storage and sales facilities for refrigerated and frozen goods. Two methods for continuous power control are known:
a) Die Saugdrosselregelung b) Die Heissgasbypassregelunga) The suction throttle control b) The hot gas bypass control
Saugdrosselregelungen weisen ein Regelventil in der Saugleitung zwischen Verdampfer und Verdichter auf. Sie drosseln bei sinkendem Kühlbedarf den umlaufenden Kältemittelfluss durch Schliessen des Regelventils. Es sinkt dadurch die Kühlleistung der Kältemaschine. Um den minimalen Gasfluss zum Verdichter sicherzustellen, muss über dem Regelventil entweder ein Bybass vorgesehen werden, oder durch Heissgasbeimischung und Nachspritzung in die Saugleitung die notwendige Etsatzgasmenge bereit gestellt werden. Saugdrosselregelungen weisen jedoch wesentliche Nachteile auf:Suction throttle controls have a control valve in the suction line between the evaporator and the compressor. If the cooling requirement drops, they throttle the circulating refrigerant flow by closing the control valve. This reduces the cooling capacity of the chiller. In order to ensure the minimum gas flow to the compressor, either a bybass must be provided above the control valve or the necessary quantity of replacement gas must be made available by adding hot gas and spraying it into the suction line. However, suction throttle controls have significant disadvantages:
- Um eine gute Regelbarkeit zu erreichen, muss das Saugdrosselventil einen möglichst grossen Drosselwiderstand aufweisen. Dieser zusätzliche Widerstand muss durch höhere Ver dicht erleistung und -Arbeit überwunden werden.- In order to achieve good controllability, the suction throttle valve must have the greatest possible throttle resistance. This additional resistance has to be overcome by higher compressor performance and work.
- Der Mi nim a l b y p s s über das Regelventil schränkt den stetig regelbaren Leistungsbereich stark ein.- The min a l b y p s s via the control valve severely limits the continuously controllable power range.
- Heissgasbypass-, Nachspritz- und Expansionsventile sind in der Regel selbstätige Regelorgane. Ihre Eigendynamik führt zu zusätzlichen Störgrössen, was die genaue Regelung erheblich erschweren kann.- Hot gas bypass, post-injection and expansion valves are usually self-regulating elements. Their own dynamics lead to additional disturbance variables, which can make the precise regulation considerably more difficult.
- Die durch das Regelventil erzeugte Drosselung führt zu sinkender Gasgeschwindigkeit in der Saugleitung und kann dadurch die Delrückführung in den Verdichte beeinträchtigen.- The throttling generated by the control valve leads to a decrease in gas velocity in the suction line and can thereby impair the del return flow in the compressions.
Heissgasbypass-Regelungen v e r f ü g e n über ein Regelventil in der Kurzschluss-Leitung zwischen der Druckseite nach dem Verdichter und der Wiederdruckseite. Bei der direkten Heissgasbypass-Regelung mündet der Kurzschluss vor dem Verdichter, saugseitig ein, während bei der indirekten Heissgasbypass-Regelung der Kurzschluss zwischen Expansionsventil und Verdampfer in die Flüssigkeitsleitung einmündet.Hot gas bypass control is via a control valve in the short-circuit line between the pressure side after the compressor and the pressure side. In the case of direct hot gas bypass control, the short circuit in front of the compressor opens on the suction side, while in the case of indirect hot gas bypass control the short circuit between the expansion valve and evaporator opens into the liquid line.
Heissgasbypass-Regelungen weisen in der Regel folgende Nachteile auf:Hot gas bypass regulations generally have the following disadvantages:
- Durch die Heissgasbeimischung sinkt die Druckdifferenz über dem Verdichter. Dies führt im Teillastbereich zu gleichbleibendem oder sogar steigendem Leistungsbedarf des Verdichters. Diese Art der Regelung ist daher für grössere Anlagen unwirtschaftlich.- The hot gas admixture reduces the pressure difference across the compressor. This leads to a constant or even increasing power requirement of the compressor in the partial load range. This type of regulation is therefore uneconomical for larger systems.
- Bei der direkten Heissgasbeimischung ist in der Regel ein Nachspritzventil erforderlich. Ausserdem ist die freie Plazierung des Verdampfers gegenüber dem Verdichter eingeschränkt.- As a rule, a post-injection valve is required for direct hot gas admixture. In addition, the free Placement of the evaporator in relation to the compressor is restricted.
Das hier vorgeschlagene Regelverfahren hebt sich vom bisher Bekannten durch folgende Punkte ab:The control procedure proposed here stands out from the previously known by the following points:
- Anstelle eines Expansionsventils (thermisch oder elektronisch gesteuert) wird ein elektronisch betätigtes Regelventil (Pos 1 , fig 1 ) vorgeschlagen, das durch eine Vielzahl von Regelgrössen positioniert werden kann. Es regelt primär bedarfsabhängig die Kälteleistung.- Instead of an expansion valve (thermally or electronically controlled), an electronically operated control valve (item 1, fig 1) is proposed, which can be positioned using a large number of control variables. It primarily regulates the cooling capacity as required.
- Die Ueberhitzung wird nicht auf einen konstanten liiert geregelt, sondern variiert lastabhängig.- The overheating is not regulated to a constant ratio, but varies depending on the load.
- Im Vollastfall wird die Leistung der Kältemaschine optimiert, indem der Verdampfer mit Kältemittel soweit gefüllt wird, bis ein elektronischer Differenzregler bei Unterschreiten der einstellbaren, minimalen Ueberhitzung die Kältemittelzufuhr drosselt.- In the case of full load, the performance of the refrigeration machine is optimized by filling the evaporator with refrigerant until an electronic differential controller throttles the refrigerant supply when the adjustable, minimal overheating is undershot.
- Im Teillastfall wird ein möglichst tiefer Saugdruck angestrebt und durch einen Heissgasbypassregler aufrecht erhalten. Es lassen sich dadurch im Teillastbetrieb erhebliche Energieeinsparungen am Verdichter erzielen.- In partial load, the lowest possible suction pressure is aimed for and maintained by a hot gas bypass regulator. This enables considerable energy savings to be achieved on the compressor in partial load operation.
Es wird hiermit vorgeschlagen, für die Regelung der Kühlleistung die umlaufende Kältemittelmenge durch ein elektronisches Drosselorgan (Pos 1. fig 1 ) zu beeinflussen. Es wird anstelle des Expansionsventils, in der Flüssigkeitsleitung zwischen Verflüssiger (Pos 2. fig 1 ) und Verdampfer (Pos 3. fig 1 ), vorgesehen.It is hereby proposed to influence the circulating amount of refrigerant by means of an electronic throttle element (item 1, fig. 1) for regulating the cooling capacity. It is used instead of the expansion valve in the liquid line between the condenser (item 2. fig 1) and the evaporator (item 3. fig 1).
In Funktion der Abweichung zwischen der Regelgösse x und der Führungsgrösse w erzeugt der Regler (RR fig 1 ) ein Stellsignal yR, welches das Ventil positioniert. Steigende Abweichungen (x - w) führen zum Oeffnen des Regelventils. Als Folge fliesst mehr Kältemittel, die Kühlleistung steigt entsprechend. Sinkt der Kühlbedarf, drosselt das Regelvenventil den Kältemittelfluss. Schliesst das Ventil, würde der Verdichter (Pos 5. fig 1) den Verdampfer leersaugen und durch den Niederdruckpressost at en (NP fig 2) abgestellt. Um die für den Verdichter im Teillastbetrieb minimal notwendige Gasmenge sicherzustellen, ist zwischen der Hoch- und Niederdruckseite eine Kurzschlussleitung (Pos 5. fig 2) vom Verdichter zum Verdampfer vorgesehen. Diese Kurzschlussleitung ist durch ein selbsttätiges Heissgasbypassventil (Pos 7. fig 2) oberhalb eines bestimmten Saugdruckes ps dicht geschlossen. Sinkt hingegen der Saugdruck ps unter einen am Heissg asbyp assventil mechanisch eingestellten Wert, so öffnet es die Kurzschlussleitung. Der Saugdruck ps stabilisiert sich damit auf dem eingestellten Druckniveau, unabhänig von der Regelventilstellung.As a function of the deviation between the controlled variable x and the reference variable w, the controller (RR fig 1) generates an actuating signal yR which positions the valve. Increasing deviations (x - w) lead to the control valve opening. As a result, more refrigerant flows and the cooling capacity increases corresponding. If the cooling requirement drops, the control valve reduces the refrigerant flow. If the valve closes, the compressor (item 5. fig 1) would empty the evaporator and be switched off by the low pressure pressostat (NP fig 2). In order to ensure the minimum amount of gas required for the compressor in part-load operation, a short-circuit line (item 5. fig 2) is provided between the high and low pressure sides from the compressor to the evaporator. This short-circuit line is tightly closed by an automatic hot gas bypass valve (item 7. fig 2) above a certain suction pressure ps. On the other hand, if the suction pressure ps falls below a value mechanically set on the hot gas bypass valve, it opens the short-circuit line. The suction pressure ps thus stabilizes at the set pressure level, regardless of the control valve position.
Um den Verdampfer vor Ueberflutung und den Verdichter vor Flüssigkeitsschlägen zu schützen, wird durch einen weiteren Regelkreis, bestehnd aus den Temperaturfühlern to (Verdampfungstemperatur) und ts (Sauggastemperatur) (to, ts fig 2) eine minimale Temperaturdifferenz Δt (ts - to) aufrecht erhalten. Diese Differenz wird mit dem Sollwert Δ t w laufend verglichen und durch den Differenzregler (DR fig 2) in ein Stellsignal y Δt umgesetzt. Das Stellsignal verstärkt sich bei steigender Temperaturdifferenz Δt (auch Ueberhitzung genannt) und schwächt sich bei abnehmender Ueberhitzung entsprechend ab. Das Regelventil drosselt dann die Kältemittelzufuhr in den Verdampfer so lange, bis die gewünschte minimale Ueberhitzung erreicht ist. Die Ueberhitzung sinkt in der Regel bei voller Kühlleistung, weil das Regelventil (Pos 1. fig 1) voll öffnet. Durch eine genaue, knappe Ueberhitzungsregelung kann die Kühlleistung einer Kältemaschine erheblich optimiert werden. Je knapper die Ueberhitzung gewählt wird, desto besser wird der Füll grad des Verdampfers. Entsprechend steigt die vom Verdampfer abgegebene Kühlleistung.In order to protect the evaporator from flooding and the compressor from liquid hammer, a minimum temperature difference Δt (ts - to) is maintained by a further control circuit consisting of the temperature sensors to (evaporation temperature) and ts (suction gas temperature) (to, ts fig 2) . This difference is continuously compared with the setpoint Δ tw and converted into a control signal y Δt by the differential controller (DR fig 2). The control signal increases with increasing temperature difference Δt (also called overheating) and weakens accordingly with decreasing overheating. The control valve then throttles the refrigerant supply into the evaporator until the desired minimal overheating is reached. The overheating usually drops at full cooling capacity because the control valve (item 1. fig 1) opens fully. The cooling capacity of a refrigeration machine can be significantly optimized through precise, brief overheating control. The scarcer the overheating is chosen, the better the filling degree of evaporator. The cooling capacity emitted by the evaporator increases accordingly.
Ein Logikmodul ( LM fig 2) vergleicht laufend die Stellsignale der Leistungsregelung yR und der Ueberhitzungsregelung yΔt. Es wählt zwischen den zwei Steilsignalen immer das kleinere aus. Ist das Stellsignal yR grösser oder gleich yΔt so wird yΔt auf das Regelventil (Pos 1. fig 1.2.3) geführt. In aller Regel liegt dann der maximale Lastfall vor.A logic module (LM fig 2) continuously compares the control signals of the power control yR and the superheat control yΔt. It always selects the smaller one between the two steep signals. If the control signal yR is greater than or equal to yΔt, yΔt is fed to the control valve (item 1. fig 1.2.3). As a rule, the maximum load case is then available.
Es wirkt somit ausschliesslich der Ueberhitzungsregler auf das Regelventil. Verändern sich hingegen die Stellsignale zu yR kleiner als y Δ t , wählt das Logikmodul (LM fig 2,3) das Stellsignal yR. Es liegt dann Teillast vor, der Verdampferfüllgrad sinkt und die Ueberhitzung nimmt zu. Es steigt damit das Stellsignal y Δ t, während das Stellsignal yR sich abschwächt, wenn der Kühlbedarf sinkt. Das Regelventil beginnt dann den Kältemittelfluss zu drosseln. Als Folge sinkt auch der Verdampfungs- und Saugdruck ps. Sinkt der Verdampfungsdruck unter einen bestimmten liiert ps, öffnet das selbsttätige Heissgasbypassventil und liefert dem Verdichter das notwendige Ersatzgas.The superheating controller thus acts exclusively on the control valve. If, on the other hand, the control signals change to yR less than y Δ t, the logic module (LM fig 2,3) selects the control signal yR. Then there is partial load, the evaporator fill level drops and the overheating increases. The control signal y Δ t thus increases, while the control signal yR weakens when the cooling requirement drops. The control valve then begins to throttle the refrigerant flow. As a result, the evaporation and suction pressure ps also decrease. If the evaporation pressure falls below a certain fixed ps, the automatic hot gas bypass valve opens and supplies the compressor with the necessary replacement gas.
Wird ein Leersaugen des Verdampfers ("pump-down") während den Stillstandszeiten gewünscht, so kann zwischen der Druckseite und dem Heissgasbypass ein dichtschliessendes "auf-zu" Ventil vorgesehen werden. Es sperrt während dem Pump-down den Durchfluss in der Kurzschlussleitung.If it is desired to empty the evaporator ("pump-down") during the idle times, a tightly closing "open-to" valve can be provided between the pressure side and the hot gas bypass. It blocks the flow in the short-circuit line during pump-down.
Fluss der Verdichter vor zu hohen Sauggastemperaturen geschützt werden, kann das Fühlersignal ts (fig 3) als Teil eines zusätzlichen Regelkreises für deren Ueberwachung Verwendung finden. Der Sauggasregler (RS fig 3) generiert ein Stellsignal yS, das unmittelbar und unbedingt auf das Regelventil wirkt, sobald ts über den Sollwert ws steigt. Durch dessen Oeffnen fliesst flüssiges Kältemittel in den Verdampfer und kühlt das einströmende Heissgas, bis die Sauggastemperatur wieder der Solltemperatur entspricht. If the flow of the compressors is protected against excessive suction gas temperatures, the sensor signal ts (fig 3) can be used as part of an additional control loop for monitoring them. The suction gas regulator (RS fig 3) generates an actuating signal yS that is immediate and unconditional on the The control valve acts as soon as ts rises above the setpoint ws. Through its opening, liquid refrigerant flows into the evaporator and cools the inflowing hot gas until the suction gas temperature again corresponds to the target temperature.

Claims

Patentansprüche Claims
1. Anordnung zur elektronischen, kontinuierlichen Leistung sreg elung einer Kältemaschine oder Wärmepumpe, bestehend aus einem geschlossenen Kältemittelkreislauf mit einem oder mehreren Verdampfern, Verdichtern und Verflüssigern, d a d u r c h g e k e n n z e i c h n e t, dass ein Regelventil in der Flüssigkeitsleitung durch b e dar f s abh ängi g e Stellsignale eines Regelsystems elektronisch positioniert wird1. Arrangement for the electronic, continuous power control of a chiller or heat pump, consisting of a closed refrigerant circuit with one or more evaporators, compressors and condensers, characterized in that a control valve in the liquid line is electronically positioned by means of dependent control signals from a control system becomes
2. Anordnung zur kon t inui er lieh en Leistungsregelung nach dem Anspruch 1, d a d u r c h g e k e n n z e i c h n e t, dass die Bedarf ssignale Regelgrössen des zu kühlenden Mediums und der Maschine selbst darstellen können.2. Arrangement for continuous power control according to claim 1, which also means that the demand signals can represent control variables of the medium to be cooled and the machine itself.
3. Anordnung zur kontinuierlichen Leistungsregelung nach3. Arrangement for continuous power control after
Anspruch 1 und 2, d a d u r c h g e k e n n z e i c h n e t, dass die minimale Gasüberhitzung am Verdampferausgang durch einen Differenzregler überwacht wird und andere Stellsignale übersteuernd, das Regelventil neu positioniert, falls die Differenz zwischen Sauggas- und Verdampfungstemperatur einen bestimmten, einstellbaren Wert unterschreitet.Claims 1 and 2, that the minimum gas overheating at the evaporator outlet is monitored by a differential controller and overrides other control signals, repositioning the control valve if the difference between the suction gas and the evaporation temperature falls below a certain, adjustable value.
4. Anordnung zur Ueberwachung einer maximal zulässigen Sauggastemperatur, d a d u r c h g e k e n n z e i c h n e t , dass das4. Arrangement for monitoring a maximum permissible suction gas temperature, that is, that the
Regelventil von einem Temperaturregler neu positioniert wird, sobald die Sauggastemperatur über einen bestimmten, einstellbaren Wert steigt.Control valve is repositioned by a temperature controller as soon as the suction gas temperature rises above a certain, adjustable value.
5. Anordnung eines Heissgasbypassventils, d a d u r c h g e k e n nz e i c h n e t , dass von der Hoch- auf die Niederdruckseite, entweder vor oder nach dem Verdampfer, Heissgas mit einem Heissgasbypassregler als Ersatzvolumen für den Verdichter bereitgestellt wird, sobald der Saugdruck aufgrund der Stellwirkung des Regelventils unter einen einstellbaren, minimalen Wert fällt.5. Arrangement of a hot gas bypass valve, characterized in that, from the high to the low pressure side, either before or after the evaporator, hot gas with a hot gas bypass regulator is provided as a replacement volume for the compressor as soon as the suction pressure is below an adjustable one due to the actuating action of the control valve. minimum value falls.
6. Anordnung nach Anspruch 1 bis 5 , d ad u r c h g e k e n n z e i c h n e t , dass die Position des Regelventils, die Verdampfungs- und die Sauggastemperatur, sowie die Sollwerte für die Pledienregler, die minimale Ueberhitzung und die maximale Sauggastemperatur als elektronische Signale zur Fernüberwachung, -Steuerung und -Regelung zur Verfügung stehen. 6. Arrangement according to claim 1 to 5, d ad characterized in that the position of the control valve, the evaporation and the suction gas temperature, as well as the setpoints for the pledge controller, the minimum overheating and the maximum suction gas temperature are available as electronic signals for remote monitoring, control and regulation.
PCT/CH1988/000036 1988-02-15 1988-02-15 Arrangement for continuously controlling the capacity of a refrigerating machine WO1989007741A1 (en)

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Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3577743A (en) * 1969-06-10 1971-05-04 Vilter Manufacturing Corp Control for refrigeration systems
FR2539855A1 (en) * 1983-01-25 1984-07-27 Comp Generale Electricite Method and device for regulating the rate of pressure reduction in a pressure-reduction valve for the coolant fluid of a heat-pump cycle
US4478051A (en) * 1983-05-06 1984-10-23 Tyler Refrigeration Corporation Electronic temperature control system
US4506518A (en) * 1981-06-17 1985-03-26 Pacific Industrial Co. Ltd. Cooling control system and expansion valve therefor
EP0138094A2 (en) * 1983-10-01 1985-04-24 Asea Brown Boveri Aktiengesellschaft Refrigerator
EP0147356A2 (en) * 1983-12-22 1985-07-03 Carrier Corporation A control system for an electronic expansion valve in a refrigeration system
GB2168467A (en) * 1984-12-14 1986-06-18 Sanden Corp Refrigerating apparatus for an air conditioner and a refrigerator of a vehicle
EP0229942A2 (en) * 1986-01-22 1987-07-29 Otto Egelhof GmbH & Co. Regulating method for refrigerant flow to the evaporator of a cooling plant or a heat pump

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3577743A (en) * 1969-06-10 1971-05-04 Vilter Manufacturing Corp Control for refrigeration systems
US4506518A (en) * 1981-06-17 1985-03-26 Pacific Industrial Co. Ltd. Cooling control system and expansion valve therefor
FR2539855A1 (en) * 1983-01-25 1984-07-27 Comp Generale Electricite Method and device for regulating the rate of pressure reduction in a pressure-reduction valve for the coolant fluid of a heat-pump cycle
US4478051A (en) * 1983-05-06 1984-10-23 Tyler Refrigeration Corporation Electronic temperature control system
EP0138094A2 (en) * 1983-10-01 1985-04-24 Asea Brown Boveri Aktiengesellschaft Refrigerator
EP0147356A2 (en) * 1983-12-22 1985-07-03 Carrier Corporation A control system for an electronic expansion valve in a refrigeration system
GB2168467A (en) * 1984-12-14 1986-06-18 Sanden Corp Refrigerating apparatus for an air conditioner and a refrigerator of a vehicle
EP0229942A2 (en) * 1986-01-22 1987-07-29 Otto Egelhof GmbH & Co. Regulating method for refrigerant flow to the evaporator of a cooling plant or a heat pump

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