EP3486564B1 - DEVICE FOR SAFE IMPLEMENTATION OF A LEFT-SWITCHING THERMODYNAMIC CLAUSIUS RANKINE PROCESS
BASED ON WORK FLUID ADSORPTION WITH INERTGAS DISPLACEMENT - Google Patents

Description

The invention relates to irregular conditions in refrigeration circuits in which a working fluid acting as a refrigerant is conducted in a thermodynamic cycle, such as the Clausius-Rankine cycle. Mainly these are heat pumps, air conditioning systems and cooling devices, as are common in residential buildings. Residential buildings are understood to mean private houses, apartment building complexes, hospitals, hotel facilities, restaurants, combined residential and commercial buildings and commercial establishments in which people live or work permanently, in contrast to mobile devices such as automotive air conditioning systems or transport boxes, or industrial plants or medical technology devices. What these cycle processes have in common is that they generate useful heat or cold using energy and form heat transfer systems. The invention relates to a device for safely carrying out a left-turning thermodynamic Clausius-Rankine cycle using an inflammable working fluid.

The thermodynamic cycle processes used have long been known, as are the safety problems that can arise when using suitable working fluids. Apart from water, the best known working fluids at that time were flammable and toxic. In the past century, they led to the development of safety refrigerants, which consisted of fluorinated hydrocarbons. However, it was shown that these safety refrigerants damage the ozone layer, lead to global warming and that their safety-related safety led to constructive inattentiveness. Up to 70% of sales was attributable to the need to refill leaky systems and their leakage losses, which was accepted as long as this was perceived as economically justifiable in individual cases and promoted the need for replacement.

For this reason, the use of these refrigerants has been subject to restrictions, for example in the European Union through the F-Gas Regulation (EU) 517/2014.

• Im Normalbetrieb muss die Anlage absolut dicht sein.
• Weder bei einer Leckage im Kondensator noch bei einer Leckage im Verflüssiger darf Arbeitsfluid in den gekoppelten Nutzwärme- oder Nutzkältekreislauf gelangen.
• Es darf kein Arbeitsfluid aus dem Kältekreislauf unbemerkt entweichen können.
• Im Verdichter darf das Arbeitsfluid nicht durch die Lagerung entweichen.
• Im Entspannungssystem darf das Arbeitsfluid nicht durch den Ventilsitz diffundieren oder durch Kavitation zu Leckagen führen.
• Gekapselte Teile müssen für Wartungs- und Kontrollzwecke zugänglich bleiben.
• In Notfällen dürfen sich keine Gefahren einstellen.
• Die Anlage soll in vorhandene Räumlichkeiten integrierbar sein
• Das Kältemittel soll abgelassen und eingefüllt werden können.

On the one hand, it is extremely problematic to adopt the design principles for refrigerant-carrying thermodynamic processes, which seem to have proven their worth with safety refrigerants, and on the other hand to base them on the system concepts from before the safety refrigerants were introduced. This is also due to the fact that individual devices have now become complex systems, which has multiplied the number of possibilities for malfunctions and their consequences. This results, for example, in the following requirements for the security concept:

• In normal operation, the system must be absolutely tight.
• Working fluid must not enter the coupled useful heating or cooling circuit either in the case of a leak in the condenser or in the case of a leak in the condenser.
• No working fluid must be able to escape from the refrigeration cycle without being noticed.
• The working fluid in the compressor must not escape through storage.
• In the expansion system, the working fluid must not diffuse through the valve seat or lead to leaks due to cavitation.
• Encapsulated parts must remain accessible for maintenance and inspection purposes.
• No dangers may arise in emergencies.
• The plant should be able to be integrated into existing premises
• The refrigerant should be able to be drained and filled.

The concept of an emergency must be seen widely. Power outages, earthquakes, landslides, floods, fires, technical errors and extreme climatic conditions are conceivable. If the systems are operated in a network, a power failure or a network fault is also to be regarded as an emergency. Against such dangers or disturbances the device is said to be inherently safe. However, a failure of the available primary energy can also justify an emergency and must not result in the development of danger. All of these emergencies can also occur in combination.

• Haushaltskühlschränke,
• Haushaltsgefrierschränke,
• Haushaltstrockner,
• Haushaltskühl-Gefrierkombinationen,
• Kühlkammern für Hotel- und Gastronomie,
• Gefrierkammern für Hotel- und Gastronomie,
• Klimaanlage für Haus, Hotel- und Gastronomie,
• Warmwassererzeugung für Haus, Hotel- und Gastronomie,
• Beheizung für Haus, Hotel- und Gastronomie,
• Sauna-Schwimmbadanlagen für Haus, Hotel- und Gastronomie,
• Kombinierte Anlagen für die oben genannten Anwendungen,

wobei diese Aufzählung nicht vollständig ist.The various designs and applications for such thermodynamic cycle processes have to be considered separately, for example the following for fixed systems for residential buildings:

• Household refrigerators,
• Freezers,
• Household dryer,
• Household fridge-freezers,
• Cooling chambers for hotel and catering,
• Freezers for hotels and restaurants,
• Air conditioning for home, hotel and catering,
• Hot water generation for home, hotel and catering,
• Heating for home, hotel and catering,
• Sauna swimming pool facilities for home, hotel and catering,
• Combined systems for the above-mentioned applications,

this list is not exhaustive.

• Erdwärme aus Erdwärmespeichern,
• Geothermische Wärme,
• Fernwärme,
• Elektrische Energie aus allgemeiner Stromversorgung,
• Elektrische Solarenergie,
• Solarwärme,
• Abwärme,
• Warmwasserspeicher,
• Eisspeicher,
• Latentwärmespeicher,
• Fossile Energieträger wie Erdgas, Erdöl, Kohle,
• Nachwachsende Rohstoffe wie Holz, Pellets, Biogas,
• Kombinationen aus den oben genannten Energiequellen,

wobei auch diese Aufzählung nicht vollständig ist.The energy for operating the systems, including the thermal energy to be moved, can come from various sources:

• Geothermal energy from geothermal energy storage,
• Geothermal heat,
• District heating,
• Electrical energy from general power supply,
• Electrical solar energy,
• Solar heat,
• Waste heat,
• Hot water tank,
• Ice storage,
• Latent heat storage,
• Fossil energy sources such as natural gas, oil, coal,
• Renewable raw materials such as wood, pellets, biogas,
• Combinations of the above energy sources,

although this list is also not complete.

The problems that arise with the safety design of such systems are discussed in the WO 2015/032905 A1 described vividly. The lower ignition limit of propane as working fluid is approximately 1.7 percent by volume in air, which corresponds to 38 g / m ³ in air. If the cooling process is carried out in a surrounding, hermetically sealed, but otherwise air-filled room with the working fluid propane, there is the problem of recognizing a critical, explosive situation after a fault in which the working fluid escapes into this hermetically sealed room. Electrical sensors for the detection of critical concentrations are difficult to carry out explosion-proof, which is why the propane detection by the sensors themselves considerably increases the risk of explosion, with the exception of infrared sensors. Propane is also toxic; when inhaled above a concentration of approx. 2 g / m ³ , there are narcotic effects, headaches and nausea. This affects people who are supposed to solve a recognized problem on site before there is a risk of explosion.

Propane is also heavier than air, so it sinks to the ground in calm air and accumulates there. If a part of the propane is collected in a low-flow zone of the enclosed space in which the faulty unit is located, the local explosion limits can be reached much faster than the quotient of the total volume of space to the amount of propane escaped. The WO 2015/032905 A1 seeks to solve this problem by integrating an electric current generator into the opening or locking of this space and, when actuated, in a first step generates and provides the electrical energy with which the sensor is activated, and which in the event of an alarm Locking then does not release, but causes ventilation of the closed room and only allows unlocking and opening in a second step.

Already at the beginning of the technology of the compression chillers, an attempt was made to form a closed room in which the equipment could all be safely accommodated and which completely encased it. The DE-PS 553 295 describes an encapsulated compression refrigeration machine in which the refrigerant compressor 1, its drive motor 2, evaporator 3, condenser 4 and control valve 5 are enclosed in a double-walled capsule 6 and 7, respectively. A vacuum is created in the space between the double-walled capsule and any leaks that could occur at the openings for cooling water and brine are extracted. The extracted working fluid can then be recovered if necessary. It should be noted that there is no ambient air inside the encapsulated room and, due to the negative pressure in the double jacket, it cannot penetrate into the encapsulated interior.

The DE 10 2011 116 863 A1 describes a method for securing a device for a thermodynamic cycle, which is operated with a process fluid that contains or consists of at least one environmentally hazardous, toxic and / or flammable substance. In the event of a leak in the device for a thermodynamic cycle, an adsorbent is brought into contact with the process fluid, in particular ammonia, propane or propene, and the substance is selectively bound by the adsorbent. The adsorbent is regenerated after use. As an adsorbent, zeolite, also in combination with imidazole or phosphates, CuBTC are also proposed. The adsorbent can be in the form of a bed, a shaped body, a paint, one Spray film or a coating. The support structure of the molded body can consist of microstructure, lamella structure, tube bundle, tube register and sheet metal and must be mechanically stable and greatly increase the surface area. Circulation of the potentially contaminated air usually takes place continuously, but can also be initiated by a sensor that switches on the ventilation after a threshold value has been reached or in the event of a recognized accident. The adsorption can be carried out inside or outside a closed room. In addition, the DE 10 2011 116 863 A1 a device according to the preamble of claim 1.

The DE 195 26 980 A1 describes a device and a method for cleaning air in closed rooms which have a gaseous contamination. After the contamination has been detected by a gas sensor, the latter controls a compressor which directs the air through an absorber located in this room, as a result of which the contamination is absorbed. The cleaned air leaves the absorber in the closed room.

The DE 195 25 064 C1 describes a refrigeration machine with a gas-tight housing, which accommodates all refrigerant-carrying components of the machine, a space is provided that connects the interior of the gas-tight housing with an outlet, and the space is filled with a substance that sorbs the refrigerant. The amount of sorbent material is dimensioned so that the entire amount of any refrigerant escaping can be absorbed and kept away from the environment. The space filled with the sorbent material is open to the surroundings. With refrigerants that are heavier than air, the space is open at the bottom, with those that are lighter, it is open at the top, so that a delivery fan is not required. The sorbent is introduced into the housing and completely surrounds the refrigeration machine or the refrigerant-carrying devices. On its way out, baffles are provided that prevent short circuit currents and force escaping gas through the sorbent. A double-walled embodiment, in which the sorbent is arranged in the double jacket, is possible. A measuring device for refrigerants can be provided at the exit of the space filled with the sorbent to the surroundings.

The EP 3 106 780 A1 describes a heat pump system which is housed in an airtight housing lined with a binder. An adsorption unit with forced ventilation, which cleans the air in the housing in recirculation mode, can be arranged within this housing. This air recirculation mode can be carried out continuously or only in the event of a fault or at regular intervals. A pilot burner, a pilot flame, a catalytic burner or a heating wire can also be arranged downstream of this sorption stage, which burns any remaining combustible impurities. A fresh air supply in connection with the discharge of cleaned exhaust air is also conceivable.

• Montagefreundlichkeit: Im Falle von Modernisierungen von alten Heizungsanlagen müssen die neu zu installierenden Vorrichtungen zerlegbar und transportabel sein. Beispielsweise müssen sie über Kellertreppen und in verwinkelte und niedrige Kellerräume verbracht werden können. Zusammenbau, Inbetriebnahme und Wartung müssen ohne großen Aufwand vor Ort möglich sein. Dies schließt große und schwere Druckbehälter weitgehend aus, ferner Systeme, die nach einer Havarie nicht mehr demontierbar sind.
• Diagnosefreundlichkeit: Die Betriebszustände sollten von außen gut erkennbar sein, dies betrifft die Sichtbarkeit und Prüfbarkeit bezüglich möglicher Leckagen und schließt den Füllstand des Arbeitsfluids sowie den Befüllungsgrad ggf. eingebrachter Sorbentien ein.
• Wartungsfreundlichkeit: Systemdiagnosen sollten ohne großen zusätzlichen Aufwand erfolgen können. Sicherheitsrelevante Systeme sollten regelmäßig getestet bzw. auf ihre Zuverlässigkeit geprüft werden können. Sofern Systemdiagnosen nicht einfach durchführbar sind, sollten möglicherweise belastete Teile leicht durch Neuteile austauschbar sein.
• Ausfallsicherheit: Die System sollen einerseits gegen Störungen gesichert sein, gleichzeitig aber zuverlässig laufen können, wenigstens im Notbetrieb. Im Falle einer vorübergehenden externen Störung sollten die Systeme entweder selbstständig wieder anfahren oder ohne großen Aufwand wiederangefahren werden können.
• Energieeffizienz: Die Anlagen sollen energetisch günstig betrieben werden können, ein hoher Eigenverbrauch an Energie für Sicherheitsmaßnahmen wirkt dem entgegen.
• Robustheit: Im Falle größerer Störungen, seien sie extern oder systemintern aufgeprägt, muss die Beherrschbarkeit gewährleistet sein, dies betrifft z.B. Lüftungssysteme, die verstopfen können oder Druckbehälter, die unter Druck stehen oder heiß werden, etwa bei einem Brand.
• Kosten: Die Sicherheitsmaßnahmen sollen weder bei den Anschaffungskosten noch bei den laufenden Kosten bedeutend sein und die Einsparungen bei den Energiekosten gegenüber herkömmlichen Systemen übersteigen. Sie sollen günstig sein.

The systems presented have so far had little success on the market. This can be attributed to the following reasons:

• Ease of installation: In the case of modernization of old heating systems, the new devices to be installed must be dismantled and transportable. For example, they must be able to be moved up and down cellar stairs and into angled and low cellars. Assembly, commissioning and maintenance must be possible on site without much effort. This largely excludes large and heavy pressure vessels, as well as systems that cannot be dismantled after an accident.
• Ease of diagnosis: The operating states should be clearly recognizable from the outside, this concerns the visibility and testability with regard to possible leaks and includes the level of the working fluid and the degree of filling of any sorbents that may have been introduced.
• Ease of maintenance: System diagnostics should be able to be carried out without much additional effort. Security-relevant systems should be tested regularly or on their Reliability can be checked. If system diagnoses are not easy to carry out, it should be easy to replace parts that are under load with new parts.
• Reliability: On the one hand, the systems should be secured against malfunctions, but at the same time they should run reliably, at least in emergency operation. In the event of a temporary external fault, the systems should either restart independently or be restarted with little effort.
• Energy efficiency: The plants should be able to be operated at low energy costs, a high self-consumption of energy for security measures counteracts this.
• Robustness: In the event of major malfunctions, be they external or internal to the system, controllability must be ensured, for example, ventilation systems that can clog or pressure vessels that are under pressure or become hot, for example in the event of a fire.
• Costs: The security measures should not be significant in terms of acquisition costs or running costs and should not exceed the savings in energy costs compared to conventional systems. They should be cheap.

The object of the invention is therefore to provide an improved lining device which better solves the problems presented and no longer has the disadvantages.

• mindestens einen Verdichter für Arbeitsfluid,
• mindestens eine Entspannungseinrichtung für Arbeitsfluid,
• mindestens zwei Wärmeübertrager für Arbeitsfluid mit jeweils mindestens zwei Anschlüssen für Wärmeüberträgerfluide,
• ein geschlossenes Gehäuse, welches alle am geschlossenen Arbeitsfluidumlauf angeschlossenen Einrichtungen umfasst, weitere Einrichtungen umfassen kann, und mit einem Adsorbens ausgekleidet ist, welches in der Lage ist, Arbeitsfluid zu adsorbieren,
• wobei ein Adsorbens eingesetzt wird, welches das Arbeitsfluid und ein Inertgas adsorbieren kann,
• wobei das Arbeitsfluid eine höhere adsorptive Bindung an das Adsorbens als das Inertgas aufweist,
• und wobei das Adsorbens, mit dem das Gehäuse ausgekleidet wird, mit dem Inertgas gesättigt vorbeladen ist.

The invention solves this problem by a device according to claim 1. The device is for safely performing a left-turning thermodynamic Rankine cycle by means of an inflammable working fluid, which is heavier than air in the gaseous state under atmospheric conditions and is guided in a closed, hermetically sealed working fluid circuit is having

• at least one compressor for working fluid,
• at least one relaxation device for working fluid,
• at least two heat exchangers for working fluid, each with at least two connections for heat transfer fluids,
• a closed housing which comprises all devices connected to the closed working fluid circulation, can comprise further devices, and is lined with an adsorbent which is capable of adsorbing working fluid,
• an adsorbent is used which can adsorb the working fluid and an inert gas,
• the working fluid having a higher adsorptive bond to the adsorbent than the inert gas,
• and wherein the adsorbent with which the housing is lined is preloaded saturated with the inert gas.

Heat transfer fluids are to be understood here as all gaseous or liquid media with which heat is transferred, for example air, water, brine, heat transfer oils or the like.

The advantage here is that in the event of a leak with release of the working fluid, the inert gas is displaced from the adsorbent with simultaneous adsorption of the working fluid. The displaced inert gas makes the interior of the container inert, thereby reducing the risk of explosion. In addition, the desorption of the displaced inert gas has the effect that the adsorptive heating of the adsorbent during the adsorption is significantly less, since it is no longer the total heat of adsorption that is released, but only the difference between the heat of adsorption of the working fluid and the heat of desorption of the inert gas. This also prevents working fluid that has already been adsorbed from being expelled again due to the development of heat.

In a particular embodiment of the invention, propane is used as the working fluid, activated carbon as the adsorbent and carbon dioxide as the inert gas. The activated carbon can be doped in a known manner in such a way that optimum loading by propane takes place, but chemisorption is to be avoided here, since the desorption of carbon dioxide then fails to occur.

In terms of apparatus, such a lining is preferably carried out by dimensionally stable mats or moldings which contain the adsorbent and which can be removed and removed in a simple manner after opening the housing. They are typically permeable to gas and liquid on the side facing the inside of the container through a holding grid, while the dimensional stability is ensured by a stable rear structure.

In one embodiment of the invention, it is provided that these mats or molded articles have a flat surface on the side facing the interior of the housing and have pull-down film-like blinds on their top, which are pulled over the surface like a bag in the event of disassembly and then used for the Keep disassembly and removal closed. In a further embodiment of the invention, this device is also used for assembly in order to prevent the inert gas from diffusing out of the lining prematurely.

On the back, the mats or molded bodies are fixed in a known manner by hooks or click closures.

• Fig. 1 einen Kältekreis mit einer Auskleidung,
• Fig. 2 ein Ausführungsbeispiel für einen adsorptiven Formkörper mit einer Jalousievorrichtung.

The invention is explained in more detail below with the aid of two basic diagrams. Here show:

• Fig. 1 a refrigeration circuit with a lining,
• Fig. 2 an embodiment of an adsorptive molded body with a blind device.

Fig. 1 shows a schematic diagram of a refrigeration circuit 1 with a compressor 2, a condenser 3, a pressure reduction 4 and an evaporator 5 in a closed housing 6. The housing 6 has a heat source connection 7, a heat source flow 8, a heat sink flow 9 and a heat sink connection 10. The cooling circuit 1 is operated in this example with the flammable working fluid propane, which is also known under the name R290. Propane is heavier than air, so if there is a leak in refrigeration circuit 1, it tends to sink downwards in housing 6. Due to temperature differences in the housing and corresponding convection, leakage-related propane can also be found in the interior of the housing. This housing 6 is therefore completely lined with the adsorptive lining 11.

Fig. 2 shows an adsorptive molded body of which several may or should be present in the housing, these molded bodies also being able to completely enclose the interior of the housing, especially on the underside, since propane escaping due to leakage sinks into the air. Such moldings also help to reduce noise emissions.

The exemplary adsorptive molded body 12 has an activated carbon mat 13 in its interior, which consists either of activated carbon fibers or of activated carbon pellets, which are fixed in a permeable matrix. Honeycomb bodies are also possible. On the back there is a supporting structure with click closures 14 with which the adsorptive molded body 12 is fixed on the inside of the housing 6. A permeable holding grille 15 is located on the opposite side.

For assembly and disassembly, the adsorptive molded body has a blind device 16, which consists of rollers on which films can be pulled up and rolled up on the front and back at the same time before use and pulled down after use and closed at the bottom. The foils on the front and back can be used also form a bag which has a pull closure and seals the adsorptive molded body gas-tight before and after use.

Reference symbol list

1

Refrigeration cycle

2nd

compressor

3rd

capacitor

4th

Pressure reduction

5

Evaporator

6

casing

7

Heat source connection

8th

Heat source flow

9

Heat sink flow

10th

Heat sink connection

11

Adsorptive lining

12

adsorptive molded body

13

Activated carbon mat

14

Back with click closure

15

Retaining grid

16

Blind device

17th

foil

Claims (5)

1. Device for safely carrying out a left-turning thermodynamic Clausius-Rankine cycle (1) by means of an inflammable working fluid, having a working fluid which is heavier than air in the gaseous state under atmospheric conditions, and having a closed, hermetically sealed working fluid circuit, which has

   - at least one compressor (2) for working fluid,

   - at least one pressure relief apparatus (4) for working fluid,

   - at least two heat exchangers (3, 5) for working fluid, each with at least two connections (7, 8, 9, 10) for heat transfer fluids, and having

   - a closed housing (6),

   - which comprises all apparatuses connected to the closed working fluid circuit,

   - can comprise further apparatuses,

   - and is lined with an adsorbent (11) which is able to adsorb working fluid,

   characterised in that

   - the adsorbent used can adsorb an inert gas, and the adsorbent is preloaded saturated with the inert gas,

   - wherein the working fluid has a stronger adsorptive bond to the adsorbent than the inert gas.
2. Device according to claim 1, characterised in that the adsorbent is activated carbon, the working fluid is propane and the inert gas is carbon dioxide.
3. Device according to any of claims 1 or 2, characterised in that the lining (11) by adsorbent is carried out by means of dimensionally stable mats or moulded bodies (12).
4. Device according to any of claims 1 to 3, characterised in that the dimensionally stable mats or moulded bodies (12) have a holding grid (15) which is permeable to gas and liquid and a dimensionally stable rear side structure (14) with a fastening device.
5. Device according to one of claims 1 to 4, characterised in that the dimensionally stable mats or moulded bodies (12) have a blind device (16) with which at least one film (17) can be drawn in a gas-tight manner over the dimensionally stable mats or moulded bodies.

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