DEVICE FOR THE SAFE IMPLEMENTATION OF A LEFT-ROTATING THERMODYNAMICS CYCLE

Description

[0001] The invention relates to a device for the safe implementation of a left-handed thermodynamic cycle using a flammable working fluid that is circulated in a closed, hermetically sealed working fluid circuit. An example of such a cycle that can be used in a refrigeration cycle is the Clausius-Rankine cycle. These are primarily heat pumps, air conditioning systems, and refrigeration units commonly found in residential buildings. Residential buildings are understood to include private homes, apartment complexes, hospitals, hotel complexes, restaurants, and combined residential and commercial buildings in which people live and work permanently, as opposed to mobile devices such as vehicle air conditioning systems or transport boxes, or even industrial plants or medical devices. What these cycles have in common is that they generate useful heat or useful cooling using energy and form heat transfer systems.

[0002] The thermodynamic cycles used have long been known, as have the safety problems that can arise with the use of suitable working fluids. Apart from water, the most common working fluids at the time were flammable and toxic. This led to the development of safety refrigerants consisting of fluorinated hydrocarbons in the last century. However, it became apparent that these safety refrigerants damaged the ozone layer and contributed to global warming, and that their lack of safety concerns led to negligent design. Up to 70% of sales were attributable to the need to refill leaking systems and their associated leakage losses, which was tolerated as long as it was considered economically justifiable in individual cases and encouraged the need for replacements.

[0003] 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.

[0004] It is therefore extremely problematic, on the one hand, to adopt the design principles for refrigerant-bearing thermodynamic processes that have apparently proven successful with safety refrigerants, while, on the other, to rely on system concepts from the era before the introduction of safety refrigerants. This is also due to the fact that individual devices have now become complex systems, which has multiplied the number of potential malfunctions and their consequences. This results in the following requirements for the safety concept, for example: During normal operation, the system must be completely leak-tight. Neither in the event of a leak in the condenser or condenser nor in the evaporator may working fluid enter the coupled useful heat or useful refrigeration circuit. No working fluid may escape unnoticed from the refrigeration circuit. In the compressor, the working fluid may not escape through the bearings. In the expansion system, the working fluid may not diffuse through the valve seat or cause leaks due to cavitation. Encapsulated parts must remain accessible for maintenance and inspection purposes. In an emergency, no hazards may arise. The system should be able to be integrated into existing rooms. It should be possible to drain and refill the refrigerant.

[0005] The concept of an emergency must be interpreted broadly. Possible events include power outages, earthquakes, landslides, floods, fires, technical faults, and extreme climatic conditions. If the systems are operated in a network, a power failure or disruption is also considered an emergency. The system should be inherently safe against such hazards or disruptions. However, a failure of the available primary energy can also constitute an emergency and must not result in a development of danger. All of these emergencies can also occur in combination.

[0006] The different designs and applications for such thermodynamic cycles must be considered separately, for example the following for stationary systems for residential buildings: Household refrigerators, household freezers, household dryers, household fridge-freezer combinations, cooling chambers for hotels and restaurants, freezing chambers for hotels and restaurants, air conditioning for homes, hotels and restaurants, hot water generation for homes, hotels and restaurants, heating for homes, hotels and restaurants, sauna and swimming pool systems for homes, hotels and restaurants, combined systems for the above-mentioned applications, This list is not exhaustive.

[0007] The energy for operating the plants, including the heat energy to be transferred, can come from various sources: Geothermal energy from geothermal storage, geothermal heat, district heating, electrical energy from the general electricity supply, electrical solar energy, solar heat, waste heat, hot water storage, ice storage, latent heat storage, fossil fuels such as natural gas, petroleum, coal, renewable raw materials such as wood, pellets, biogas, outside air, combinations of the above-mentioned energy sources, although this list is not complete.

[0008] The problems that arise when designing safety systems for such systems are clearly described in WO 2015 / 032905 A1. The lower flammability limit of propane as a working fluid is approximately 1.7 percent by volume in air, which corresponds to 38 g / m3 in air. If the refrigeration process is carried out in a surrounding, hermetically sealed, but otherwise air-filled space with propane as the working fluid, the problem arises of detecting a critical, explosive situation following a malfunction that causes the working fluid to escape into this hermetically sealed space. Electrical sensors for detecting critical concentrations are difficult to implement in an explosion-proof manner, which is why propane detection by the sensors themselves significantly increases the risk of explosion, with the exception of infrared sensors. Propane is also toxic if inhaled above a concentration of approx.At concentrations below 2 g / m³, narcotic effects, headaches, and nausea occur. This affects people who are expected to resolve a problem on-site before the danger of explosion arises.

[0009] Propane is also heavier than air, so it sinks to the floor in still air and collects there. If some of the propane collects in a low-flow zone of the enclosed space containing the faulty unit, the local explosion limits can be reached much faster than expected from the quotient of total space volume to the amount of propane leaked. WO 2015 / 032905 A1 seeks to solve this problem by integrating an electrical generator into the opening or its locking mechanism in this space. When activated, this generator first generates and provides the electrical energy to activate the sensor. In the event of an alarm, the generator then does not release the locking mechanism but instead ventilates the enclosed space, and only then allows unlocking and opening.

[0010] 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. Zeolite, also in combination with imidazole or phosphates, and CuBTC are proposed as adsorbents. The adsorbent can be in the form of a bed, a molded body, a paint, a spray film, or a coating.The support structure of the molded body can consist of a microstructure, a lamellar structure, a tube bundle, a tube register, or a sheet metal structure and must be mechanically stable and significantly increase the surface area. Circulation of the potentially contaminated air is usually continuous, but can also be initiated by a sensor that activates the ventilation when a threshold is reached or when an emergency is detected. Adsorption can be performed inside or outside a closed space.

[0011] DE 195 25 064 C1 describes a refrigeration machine with a gas-tight housing that accommodates all of the machine's refrigerant-carrying components. A chamber is provided that connects the interior of the gas-tight housing to an outlet, and the chamber is filled with a refrigerant-sorbent material. The amount of sorbent material is dimensioned such that any escaping refrigerant can be absorbed and kept away from the environment. The chamber filled with the sorbent material is open to the environment. For refrigerants that are heavier than air, the chamber is open at the bottom, while for lighter refrigerants, it is open at the top, eliminating the need for a conveying fan. The sorbent is introduced into the housing and completely encloses the refrigeration machine or the refrigerant-carrying equipment.On its way out, baffles are provided to prevent short-circuit flows and force escaping gas through the sorbent. A double-walled design, in which the sorbent is enclosed in the double jacket, is also possible. A refrigerant measuring device can be provided at the outlet of the chamber filled with the sorbent to the environment.

[0012] EP 3 106 780 A1 describes a heat pump system housed in an airtight casing lined with a binder. Within this casing, an adsorption unit with forced ventilation can be arranged, which cleans the air in the casing in recirculation mode. This recirculation mode can occur continuously, only in the event of a malfunction, or at regular intervals. Downstream of this sorption stage, a pilot burner, a pilot flame, a catalytic burner, or a heating wire can also be arranged, which combusts any remaining combustible contaminants. A fresh air supply in conjunction with the discharge of purified exhaust air is also conceivable.

[0013] The systems presented have had little success on the market so far. This can be attributed to the following reasons: Ease of installation: When modernizing old heating systems, the newly installed devices must be dismantled and transportable. For example, they must be able to be moved via basement stairs and into narrow, narrow basement rooms. Assembly, commissioning, and maintenance must be possible on-site without great effort. This largely excludes large and heavy pressure vessels, as well as systems that cannot be dismantled after a failure. Ease of diagnostics: Operating states should be clearly visible from the outside. This applies to visibility and verifiability with regard to possible leaks and includes the fill level of the working fluid and the fill level of any sorbents that may have been introduced. Ease of maintenance: System diagnostics should be possible without great additional effort. Safety-relevant systems should be able to be tested regularly and their reliability checked.If system diagnostics are not easily performed, potentially damaged parts should be easy to replace with new ones. Failure tolerance: The systems should be protected against malfunctions, but at the same time be able to operate reliably, at least in emergency mode. In the event of a temporary external malfunction, the systems should either restart automatically or be able to be restarted without great effort. Energy efficiency: The systems should be able to operate energy-efficiently; high internal energy consumption for safety measures counteracts this. Robustness: In the event of major malfunctions, whether external or internal to the system, controllability must be guaranteed. This applies, for example, to ventilation systems that can become blocked or pressure vessels that are under pressure or overheat, as in the event of a fire. The systems should be as quiet as possible.Costs: The security measures should not be significant in terms of either acquisition or running costs, and they should outweigh the energy savings compared to conventional systems. They should be affordable.

[0014] DE 195 25 064 C1 describes a refrigeration machine with a housing that houses the refrigerant-carrying components of the machine. While the housing is gas-tight, a chamber is provided connecting the interior of the gas-tight housing to an outlet. This chamber is filled with a refrigerant-adsorbing substance. The chamber can also be a channel open to the outside and contain baffles.

[0015] The problem here, however, is that the noise generated by the engine can penetrate unhindered through the room or duct to the outside, something that would otherwise be prevented by the closed housing if it were gas-tight. While baffles in air ducts can also prevent airborne noise from spreading, as is well known from air conditioning and ventilation technology and the exhaust system in combustion engine vehicles, these cannot be filled with refrigerant-absorbing substances. This creates a conflict of objectives. Therefore, soundproofing or sound-absorbing measures are required that cause as little pressure loss as possible during the flow.

[0016] The object of the invention is therefore to provide an improved device which is inexpensive, safe and quiet.

[0017] The invention solves this problem by a device as defined by the appended independent claim 1. This device is for the safe implementation of a left-rotating thermodynamic cycle by means of an flammable working fluid, which is guided in a closed, hermetically sealed working fluid circuit, comprising, among other things, at least one compressor for working fluid, at least one expansion device for working fluid, at least two heat exchangers for working fluid, each with at least two connections for heat transfer fluids, an inner housing which comprises all devices connected to the closed working fluid circuit and can comprise further devices, at least one external adsorber which is directly connected to the inner housing and covers and is connected to at least one side of the inner housing, the external adsorber has an unsealable outlet opening for gas, the inner housing has at least one opening for gas and, following this opening, an inflow area for gas into the external adsorber, and the external adsorber has both a gas adsorbent for flammable gas flowing through with working fluid and at least one noise absorber for structure-borne sound and airborne sound.

[0018] In most cases, a Clausius-Rankine cycle operated with R290 serves as the left-handed cycle. Heat transfer fluids are defined as any gaseous or liquid media used to transfer heat, such as air, water, brine, heat transfer oils, or the like. A similar technology is described in EP 3 693 683 A1, but without additional soundproofing measures. EP 3 693 683 A1 represents the closest prior art for the present invention. Technically more distant prior art can also be found in JP 2002 058950 A, CN 110 285 495 A, and CN 106 679 238 A.

[0019] The function of the invention is that the usual sound insulation of the housing can be largely dispensed with if this sound insulation is integrated into the device that serves to remove leak-related contamination. If this device is open to the environment, sound can also generally penetrate to the outside unhindered, and the adsorption of leak-related contamination by the air inside the housing and, due to the associated pressure increase of the escaping air, advantageously occurs jointly and in a coordinated manner.

[0020] This ensures that neither working fluid nor noise can escape to the outside, even though the housing is permeable to gas. The external adsorber of the invention thus adsorbs working fluid from the gas and simultaneously absorbs sound. Regarding the absorbed sound, both structure-borne and airborne sound are absorbed. The sound absorption device is described in more detail below.

[0021] Furthermore, within the scope of the present invention, it is provided that The external adsorber has an adsorbent bed as a gas adsorbent, at least one soft heavy-duty mat as a bed boundary, and at least one sound-insulating layer between the housing. The adsorbent bed has a soft heavy-duty mat on each of two sides as a bed boundary. The adsorbent bed is made of spheres or pellets, and the soft heavy-duty mat is so soft that the spheres or pellets can press into the heavy-duty mat.

[0022] In embodiments of the invention it is provided that the soft heavy floor mat allows the balls or pellets of the adsorbent bed to be pressed in by more than half the particle diameter, the soft heavy floor mat is made of silicone.

[0023] Heavy floor mats have long been known in the art by a variety of names. Common terms include "heavy mat," "heavy layer mat," "heavy mat," "acoustic foam," and "deadening mat," among many others. They are sold commercially, for example, as "anti-drum mats" and "self-adhesive soundproofing mats." In household appliance manufacturing, for example, DE 10 2011 116 809 A1 is known, which features and describes such a deadening mat. In automotive engineering, for example, DE 199 02 222 A1 is known, which uses a sound-insulating floor covering that explains an acoustic double-wall system between the carpet and the floor of the vehicle interior. Here, the heavy floor mat is described as "stiffening layer 8." The technology is fundamentally described in EP 733 004 B1, where the mats are referred to as "heavy layers 7, 8, 9."The principle is also described in GB 2 213 097 B, where the heavy floor mat is described as "intermediate sheet 2".

[0024] Normally, gas does not flow through the adsorbent bed unless a leak occurs. This distinguishes it from filter technology used in air conditioning systems, as described in EP 532 874 B1 for an air conditioning system for residential spaces, in which a filter is provided between the fan and the outlet. The air conditioning system can also have a heat pump function; the fan generates disturbing noises in the frequency range of 125 to 250 Hz. Deflectors and, among other things, sorption filters are used for sound insulation. The sorption filters have a carrier for the sorbent substances. Open-pore foams, also as a bed, are suggested.

[0025] Only small gas flows occur when air pressure fluctuations at the enclosure's installation location require pressure equalization between the interior and the surroundings. However, the vibrations of the installed equipment cause both structure-borne and airborne sound to be transmitted to the enclosure walls and to the gas, usually air, in the interior. In conventional designs, this is usually dampened by insulating material in the form of linings and mats made of insulating materials. Some of these commonly used materials are flammable or soluble in hydrocarbons, which is why special precautions must be taken when flammable or combustible working fluids, such as hydrocarbons such as R290, are to be used.

[0026] These measures within the housing can be dispensed with if all soundproofing measures are carried out on the outside of the inner housing. This purpose is fulfilled by the heavy floor mats, which are preferably made of silicone; depending on the working fluid, fluorosilicone is used, for example. The silicone mats should be several millimeters thick, e.g. 3 millimeters, and very soft; Shore A hardnesses between 10 and 60 are preferred. These silicone mats come into direct contact with the particles of the adsorbent bed, which preferably consists of pellets or spheres. The particles press elastically and plastically into the soft floor mats; the vibrations during operation thus create a bed with quasi-solid properties, which does not move around the edges when there is flow through it.This lack of edge penetration also means that sound waves are not reflected at the walls bordering the adsorbent bed and no gas channels are formed through which airborne sound waves can pass unhindered.

[0027] The heavy floor mats also increase the weight of the housing panels, which can be made of metal or plastic, which also significantly reduces the transmission of structure-borne noise.

[0028] This structure-borne sound insulation can be significantly improved if the insulation material, which is conventionally used inside the inner casing, is applied to the outside of the inner casing and connected to the heavy-duty floor mat. The best insulation results are achieved when the insulation material is made of elastic materials whose resonance frequency matches that of the compressor. This achieves the largest vibration amplitudes and maximizes the internal damping effect of the insulation material.

[0029] It is particularly advantageous if the external adsorber is formed from a first insulation layer that lies directly against the inner housing, followed by a heavy-duty mat, then an adsorbent bed, then another heavy-duty mat, then another insulation layer, and finally an outer housing wall. The sum of the two insulation layers can then be the same size or even smaller than the insulation layer according to conventional technology.

[0030] Depending on the installation, only one side of the housing, several sides, or all of the housing can be equipped with such an external adsorber. If the housing is positioned directly against a wall or in a corner, the wall insulation can be omitted. Furthermore, it is often difficult to ensure the gas path remains free in the event of leaks or to change the adsorption material when the unit is loaded. For freestanding units, an external adsorber can be installed on each side, which can then be designed accordingly narrower.

[0031] In most cases, the adsorbent bed is flowed through from bottom to top, with the inflow area from the inside of the inner housing at the bottom, and the adsorbent bed held at the bottom by a sieve. A top cover is not required. However, an arrangement with an inflow area at the top and an outflow area at the bottom is also possible.

[0032] The adsorbent bed must be matched to the adsorption capacity of the working fluid to be adsorbed. Activated carbon is advantageous when using the R290 working fluid. The spheres or pellets of the adsorbent bed should have a diameter range of 0.5 to 10 millimeters and a length-to-diameter ratio of 1 to 20. Spheres or cylindrical pellets with a diameter of 4 to 6 millimeters are optimal, as they press perfectly into the soft, heavy-duty silicone floor mats.

[0033] The invention is explained in more detail below using schematic diagrams. These show: Fig. 1 a heat pump with external adsorber, Fig. 2 an external adsorber according to the invention in side section, Fig. 3 a top view of an external adsorber arrangement.

[0034] Fig. 1 shows a heat pump with an external adsorber based on a schematic diagram of a refrigeration circuit 1 with a compressor 2, a condenser 3, a pressure reducer 4, and an evaporator 5 in a housing consisting of an inner housing 6 and two external adsorbers 12 surrounding the housing. The inner housing 6 is open at the bottom and closed at the top, while the external adsorber 12 is open at the top. The heat pump has a heat source connection 7, a heat source flow 8, a heat sink flow 9, and a heat sink connection 10.

[0035] In this example, refrigeration circuit 1 is operated with the flammable working fluid propane, also known as R290. Propane is heavier than air, so in the event of a leak in refrigeration circuit 1, it tends to sink to the bottom of the inner housing 6, although it mixes well with small leaks. Therefore, an opening with an inflow area 14 is provided in the lower part of the inner housing, through which an air-propane mixture from the interior 13 reaches the external adsorber 12 and then to the outlet opening 15.

[0036] Fig. 2 shows an external adsorber according to the invention in side section. If an air-propane mixture from the interior 13 reaches the external adsorber 12, it enters the activated carbon bed 123, which completely absorbs the propane. The activated carbon bed 123 is enclosed on both sides by heavy-duty silicone mats 122, which in turn are attached to conventional insulation material 121. On the housing side, the insulation material is directly connected to the inner housing 6; on the outside, an outer wall is provided, which does not require any special requirements.

[0037] Fig. 3 shows a highly simplified top view of a freestanding heat pump. The inner housing section 6 is surrounded by an external adsorber 12 on all four sides, each of which is open at the top. List of reference symbols

[0038] 1Refrigeration circuit 2Compressor 3Condenser 4Pressure reduction 5Evaporator 6Inner casing 7Heat source connection 8Heat source flow 9Heat sink flow 10Heat sink connection 11Screen support 12External adsorber 13Interior 14Inlet area 15Outlet opening 121Sound insulation layer 122Heavy floor mat 123Activated carbon filling

Claims

1. Device for the safe performance of a counterclockwise thermodynamic cycle (1) by means of an ignitable working fluid which is guided in a closed, hermetically sealed working fluid circuit, comprising - at least one compressor (2) for working fluid, - at least one expansion device (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, - an inner housing (6), which includes all devices connected to the closed working fluid circulation and can include further devices, - at least one outer adsorber (12), which is directly connected to the inner housing (6) and covers at least one side of the inner housing (6) and is connected to it - the external adsorber (12) has a non-closable outlet opening (15) for gas, - the inner housing (6) has at least one opening for gas and, adjacent to this opening, an inflow area (14) for gas into the outer adsorber (12), whereby - the external adsorber (12) has both a gas adsorber for flammable gas flowing through with working fluid and at least one sound absorber for structure-borne and airborne sound, - the external adsorber (12) has an adsorbent bed (123) as a gas adsorbent, at least one soft heavy-bottom mat (122) as a bed boundary and at least one sound-insulating layer (121) towards the housing (6), - the adsorbent bed (123) has a soft heavy soil mat (122) on each of two sides as a bed boundary, - the adsorbent bed (123) is formed from spheres or pellets and the soft heavy-bottom mat (122) is so soft that the spheres or pellets can be pressed into the heavy-bottom mat (122).

2. Device according to claim 1, characterised in that the soft heavy-bottom mat (122) allows the balls or pellets of the adsorbent bed (123) to be pressed in by more than half the particle diameter.

3. The device according to any one of claims 1 or 2, characterised in that the soft heavy bottom mat (122) is made of silicone.

4. Device according to one of claims 1 to 3, characterised in that the external adsorber (12) has at least one insulating layer (122) whose resonant frequency corresponds to that of the main oscillation of the compressor (2) of the cyclic process (1).

5. Device according to one of claims 1 to 4, characterised in that the outer adsorber (12) is formed from a first insulating layer (121), which lies directly against the inner housing (6), followed by a heavy-bottom mat (122), followed by an adsorbent fill (123), followed by a further heavy-bottom mat (122), followed by a further insulating layer (121) and followed by an outer housing wall.

6. Device according to one of claims 1 to 5, characterised in that an outer adsorber (12) is provided on each of at least 2 sides of the inner housing (6).

7. Device according to claim 6, characterised in that an outer adsorber (12) is provided on each of at least 3 sides of the inner housing (6).

8. Device according to claim 6, characterised in that an outer adsorber (12) is provided on all sides of the inner housing (6).

9. Device according to one of claims 1 to 8, characterised in that the inflow region (14) of the outer adsorber (12) is arranged at the bottom of the inner housing (6) and the adsorbent bed (123) is held by a sieve (11).

10. Device according to one of claims 1 to 8, characterised in that the inflow region of the outer adsorber (12) is arranged at the top in the inner housing (6) and the adsorbent bed (123) is held by a sieve (11).

11. Device according to one of claims 1 to 10, characterised in that the adsorbent bed (123) for gas consists of activated carbon.

12. Device according to one of claims 1 to 11, characterised in that the spheres or pellets of the adsorbent bed (123) have a diameter range of 0.5 to 10 millimetres and a lengthto-diameter ratio of 1 to 20.