DE102018127198A1 - Molded parts for heat pumps - Google Patents

Abstract

The invention relates to molded parts for introduction into the cavities in the housing of a heat pump in which an inflammable working fluid is operated in a refrigeration cycle, the molded parts being designed and matched to one another in such a way that no gap or cavity remains after the introduction into the housing that is larger than the extinguishing distance, based on a stoichiometric working fluid-air mixture.

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 complexes, restaurants and combined residential and commercial buildings in which people live and work permanently, in contrast to mobile devices such as automotive air conditioning systems or transport boxes, or also 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 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 the 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 harmlessness 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 build on the system concepts from the time before the introduction of the safety refrigerants. 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.
• - Neither in the case of a leak in the condenser nor in the case of a leak in the condenser, working fluid may get into the coupled useful heat or useful cooling circuit.
• - 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 system 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. The device should be inherently safe against such dangers or disturbances. 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,
• - household 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 systems for home, hotel and catering,
• - Combined systems for the above-mentioned applications, although 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 stores,
• - 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 fuels such as natural gas, oil, coal,
• - Renewable raw materials such as wood, pellets, biogas,
• - Combinations of the energy sources mentioned above, 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 closed room in which the faulty unit is located, the local explosion limits can be reached much faster than the quotient of the total volume of the room and the amount of propane escaping. 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 initiates ventilation of the closed room and only allows unlocking and opening in a second step.

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 molded part, a paint, a spray film or a coating. The support structure of the molded part 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 which 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.

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 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 contaminants. 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 Beherschbarkeit 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 have to be able to be moved over basement stairs and into winding and low basement rooms. 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. Safety-relevant systems should be tested regularly or their reliability should be checked. If system diagnoses are not easy to carry out, possibly contaminated parts should be easy to replace with new parts.
• - Reliability: On the one hand, the systems should be secured against malfunctions, but at the same time they should be able to 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, manageability 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 a device which ensures that the working fluid escaping in the event of a fault is either stored safely or is safely adsorbed or safely absorbed without an explosion-critical state being able to arise in the area in which the working fluid-carrying device is installed or used.

The invention solves this problem by means of moldings which are introduced into the cavities in the housing of a heat pump and fill them so comprehensively that there is no such large empty volume at any point which at least requires an ignitable refrigerant-air mixture that occurs due to leakage for ignition.

The determining variable is the so-called "quenching distance", which is the largest distance between two walls at which explosive mixtures can still not be ignited. For the working fluid propane, also known as R290, this extinguishing distance according to "Artur Gutkowski, Laminar Burning Velocity under Quenching Conditions for Propane-Air and Ethylene-Air Flames, January 2006, https://www.researchgate.net/publication / 242567175 “for a stoichiometric propane-air mixture 2 millimeters, while the distance for non-stoichiometric mixtures can be significantly larger.

At the ignition limits themselves, the permissible maximum distance is larger because the gas compositions are not stoichiometric. Nevertheless, for safety reasons, it is provided in the present case that there is no gap or cavity at any point in the housing which is greater than the extinguishing distance, based on a stoichiometric working fluid / air mixture.

This is achieved by means of molded parts that reproduce the contours of the individual installations and units of the heat pump in the housing in a stamp-matrix manner. At the points where the vibrations or small movements occur in the housing, these molded parts have soft, supple surfaces, otherwise they are divided in such a way that they can be inserted one after the other into the interior of the housing and preferably inserted one into the other. In one design variant, molded dome connectors are used for this. In another embodiment, the molded parts have tongue and groove connections. In a further embodiment, the molded parts are shaped as textile pillows. In a further embodiment, the molded parts have sections of Velcro strips with which they can be detachably connected to one another.

Further configurations result from the materials used. The molded parts are preferably made from adsorbents. Here, a non-combustible porous framework material, for example made of zeolite, can be used, which in is impregnated in a known manner with an adsorbent, for example activated carbon. A flexible material can also be used as the framework material, for example silicone foam, which is also impregnated. In the case of textile pillows, fine-grained fillings can also be used, the gap volume of which is small. These fillings can also consist of adsorbents. Instead of granular fillings, fabric mats can also be introduced into the pillow-shaped moldings. The textile upper material of the pillow-shaped molded parts preferably consists of diffusion-open textile fabric in the mesh size range of 0.1 to 6 millimeters, depending on the granule size of the filled material. The material of the textile fabric preferably consists of flame-retardant fibers that are temperature-stable up to 70 degrees Celsius from renewable raw materials.

If adsorbents are used, they can be preloaded with an inert gas, which is displaced or desorbed by the working fluid. The total loading capacity of the adsorbent introduced should be dimensioned such that, if necessary, the entire working fluid that emerges can be adsorbed.

The molded parts can also be designed so that the noise generated in the heat pump is insulated. For this purpose, molded parts should be used, the natural vibration frequency of which corresponds to the main frequencies of the installed machines, especially the compressor. Pillow-shaped moldings with sand-like fillings also provide considerable noise insulation.

• - mindestens einen Verdichter für Arbeitsfluid,
• - mindestens eine Entspannungseinrichtung für Arbeitsfluid,
• - mindestens zwei Wärmeübertrager für Arbeitsfluid mit jeweils mindestens zwei Anschlüssen für Wärmeüberträgerfluide,
• - ein geschlossenes und druckdichtes Gehäuse, welches alle am geschlossenen Arbeitsfluidumlauf angeschlossenen Einrichtungen umfasst, weitere Einrichtungen umfassen kann,
• - und mit den erfindungsgemäßen Formteilen ausgestattet ist.

The invention also encompasses the use of the molded parts in a heat pump for safely carrying out a left-turning thermodynamic Clausius-Rankine cycle using an inflammable working fluid which is heavier than air in the gaseous state under atmospheric conditions and is conducted in a closed, hermetically sealed working fluid circuit

• - 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 and pressure-tight housing, which comprises all devices connected to the closed working fluid circuit, can comprise further devices,
• - And is equipped with the molded parts according to the invention.

Here, heat transfer fluids are to be understood as all gaseous or liquid media with which heat is transferred, that is to say air, water, brine, heat transfer oils or the like.

In a particular embodiment of the invention, propane is used as the working fluid and activated carbon is used as the adsorbent. The activated carbon can be doped in a known manner in such a way that optimum loading by propane takes place.

The invention is explained in more detail below with the aid of a sketch. Here shows 1 typical molded parts and their arrangement.

1 shows a scroll compressor 1 in a section of a housing. The scroll compressor 1 is on a vibration damping foundation 2nd with rubber feet 3rd stored around the foundation is a flat molding 4th with cutouts for the rubber feet. The distance up to the scroll compressor 1 is one millimeter. The molding 4th is shaped as a foamed body impregnated with activated carbon according to the dimensions of the scroll compressor.

Above it is an annular molding 5 , which is divided in the middle, so that there are two semicircular rings, over the molded part 4th placed that flush with the suspensions of the scroll compressor 1 connects. The ring shaped part 5 is designed as a pillow and contains a dimensionally stable but flexible fabric. The two parts of the molding 5 are connected with Velcro.

Another ring-shaped molded part is located above it 6 , whose inner surface is soft on the scroll compressor 1 hugs and the body consists of a dimensionally stable rigid foam, on the top of which a pillow with a filling of activated carbon particles and a diffusion-open fabric is attached. This molding 6 extends to the working fluid inlet 7 of the scroll compressor 1 which he touches with the soft surface of the filled cushion from the bottom.

Another dimensionally stable molded part closes above the working fluid inlet 8th at that like the molding 6 is equipped, and that up to the working fluid outlet 9 enough that he touches with the soft surface of the filled cushion from the bottom. Above the working fluid outlet 9 the molded part is on the top of the scroll compressor 10th , which is formed from a pillow with a bed of activated carbon preloaded with inert gas.

The molded parts 6 and 8th are inserted into each other, the molding 10th is with Velcro on the molding 8th attached. None of the molding is with that Bottom or the scroll compressor connected directly.

As with the example of the scroll compressor, all other heat pump devices within the housing are equipped with molded parts. Due to the plug-in design, quick assembly and disassembly is ensured, in addition, the molded parts have a noise-reducing effect and adsorb the escaping working fluid in the event of leakages.

Reference list

1

Scroll compressors

2nd

foundation

3rd

Rubber feet

4th

Molding

5

Molding

6

Molding

7

Working fluid inlet

8th

Molding

9

Working fluid outlet

10th

Molding

QUOTES INCLUDE IN THE DESCRIPTION

This list of documents listed by the applicant has been generated automatically and is only included for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2015/032905 A1 [0008, 0009]
• DE 102011116863 A1 [0010]
• EP 3106780 A1 [0011]

Claims (19)

Molded parts for insertion into the cavities in the housing of a heat pump in which an inflammable working fluid is operated in a refrigeration cycle, characterized in that the molded parts (4, 5, 6, 8, 10) are designed and matched to one another in such a way that after insertion no gap or cavity remains in the housing which is greater than the extinguishing distance, based on a stoichiometric working fluid-air mixture. Molded parts after Claim 1 , characterized in that the molded parts are reproduced in the stamp matrix manner of the contours of the individual installations and units of the heat pump in the housing. Molded parts after Claim 1 , characterized in that the molded parts, which are modeled on the vibrating parts of the heat pump, have soft, conformable surfaces with respect to these vibrating surfaces. Molded parts after Claim 1 , characterized in that the molded parts are divided and can be used one after the other in the interior of the housing. Molded parts after Claim 4 , characterized in that the molded parts can be inserted into one another. Molded parts after Claim 4 , characterized in that the molded parts can be connected with dome connectors. Molded parts after Claim 4 , characterized in that the molded parts have tongue and groove connections. Molded parts after Claim 4 , characterized in that the molded parts have sections of Velcro strips with which they can be releasably connected to one another. Molded parts after Claim 4 , characterized in that the molded parts are shaped as textile pillows. Molded parts according to one of the Claims 1 to 9 , characterized in that the moldings contain adsorbents. Molded parts according to one of the Claims 1 to 9 , characterized in that the molded parts contain absorbents. Molded parts according to one of the Claims 1 to 9 , characterized in that the molded parts have a non-combustible framework material. Molded parts after Claim 12 , characterized in that the molded parts are impregnated with an adsorbent. Molded parts according to one of the Claims 9 to 13 , characterized in that the molded parts have fine-grained fillings with a small gap volume. Molded parts after Claim 12 , characterized in that the upper material of the molded parts is made of diffusion-open textile fabric that is stable up to 70 degrees Celsius in the mesh size range of 0.1 to 6 millimeters. Molded parts according to one of the Claims 10 to 15 , characterized in that the adsorbents of the molded parts are preloaded with an inert gas. Molded parts according to one of the Claims 1 to 16 , characterized in that the natural vibration frequency of the molded parts corresponds to the main frequencies of the installed machines. Use of molded parts according to one of claims 1 to 17 for a heat pump, the working fluid of which is propane and the extinguishing distance is 2 millimeters. Use of molded parts according to one of claims 1 to 18 for a heat pump in which a left-turning thermodynamic Clausius-Rankine cycle with an inflammable working fluid, which is conducted in a closed, hermetically sealed working fluid circuit - 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, at least one of the heat exchangers is designed as a condenser, - a closed housing, - which includes all devices connected to the closed working fluid circuit, - And may include other facilities.

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