PLATE HEAT EXCHANGER AND HEATING OR COOLING SYSTEM

Description

[0001] The invention relates to a plate heat exchanger and a heating or cooling system with a heat pump or refrigeration system which includes such a plate heat exchanger.

[0002] Due to their lack of sustainability, heat pumps and refrigeration systems using climate-damaging refrigerants will no longer be permitted in the future. However, all known alternative refrigerants have significant drawbacks: Water, as a refrigerant, requires very low pressure and, due to its large volume, is only suitable for very high-capacity applications. Ammonia is toxic and develops a pungent odor even at minute concentrations.

[0003] Therefore, flammable or toxic refrigerants are often chosen, but their use is then regulated by strict quantity limits and safety precautions. An important safety regulation is that flammable refrigerants may only enter residential buildings in limited quantities. For this reason, the heat pump or chiller is preferably installed outside the building. Only the heating water heated by the heat pump or chiller is piped into the building and transported to the heating appliances located there.

[0004] Furthermore, a heat exchanger is required in the heat pump or refrigeration system to separate the refrigeration circuit from the heating water. If the heat exchanger itself develops an internal leak, refrigerant can enter the cooling or heating circuit and thus be transported into the building via the heating water through the pipes. The refrigerant can then enter the living spaces via vent valves, for example, on the cooling or heating units. To prevent such mixing of refrigerant and cooling water, heating water, or drinking water, double-walled heat exchangers are often used when flammable refrigerants are employed.

[0005] A plate heat exchanger is typically composed of several plate-shaped heat exchangers, the heat transfer plates, which are shaped with a corrugated pattern, such as a herringbone pattern with wave-like profiling. These heat transfer plates are stacked alternately rotated 180° relative to each other and soldered together at contact points, creating flow channels between them for two heat exchange media. When the plate heat exchanger is in operation, the two heat exchange media, for example, the heating water and the refrigerant, flow in opposite or parallel directions along opposite surfaces of each heat transfer plate. Heat is transferred between the two heat exchange media through the heat exchanger plate. A heat exchanger plate can, for example, have a thickness of 0.4 mm.A plate heat exchanger according to the preamble of claim 1 is known from KR 2016 0012404.

[0006] In double-walled plate heat exchangers, instead of a single 0.4 mm thick heat exchanger plate, two heat exchanger plates made of 0.2 mm thick sheet metal are used, joined only at a few points. The joined sheets are soldered together in the same way to form a stack of plates, creating a double plate (cassette). Leaks are intended to be visible to the outside through the gap in the cassette. However, this design has several weaknesses: When soldering the heat exchanger plates with copper, it is not easy to avoid soldering the gap between the two sheets of each cassette. Often, the sheets are unintentionally soldered together without the soldered joints being detected. Due to internal pressure, the heat exchanger plates of the cassettes deform differently, which can lead to gaps in the cassettes and impair heat transfer.Due to internal pressure-induced deformation, the accidentally soldered areas are stiffer than the rest. The areas adjacent to the solder joints are severely deformed, increasing the risk of cracking. Ultimately, defects in double-walled heat exchanger plates can only be detected through observation.

[0007] The object of the invention is to provide a heating or cooling system with a plate heat exchanger which does not have the aforementioned disadvantages, is reliable and safe to operate and can be manufactured and installed with little additional effort.

[0008] The problem is solved according to the invention by a plate heat exchanger with the features of claim 1 and by a heating or cooling system with the features of claim 6, as well as a method with the features of claim 10. Advantageous embodiments of the invention are listed in the dependent claims.

[0009] The invention is based on the consideration that a leak within the plate heat exchanger leads to the mixing of the liquid and the gas, or to the gas entering the liquid and being carried along in the form of gas bubbles. The gas separator separates the gas from the liquid so that it can no longer enter the liquid circuit. The liquid is, in particular, water, specifically heating water used in a heating system within a building, especially within living spaces. Alternatively, however, other liquids or mixtures of these liquids with water can also be used. The gas used as a refrigerant, for example propane, is generally flammable and must therefore not enter living spaces.

[0010] The plate stack is formed from stacked heat transfer plates, which are profiled and connected at the points of contact of the profiles, in particular by soldering, such that first flow channels for the evaporating or condensing liquid and second flow channels for the gas are formed between them. The liquid enters the plate stack through a liquid inlet opening and exits it through an outlet opening. According to the invention, a gas separator is arranged at this outlet opening, which is designed to separate the gas carried along with the liquid from the liquid. The gas separator is thus arranged outside the plate stack, but can also advantageously be integrated into the plate stack.

[0011] Preferably, the gas separator is arranged directly at the outlet opening. At this location, the liquid has its highest temperature, at least in a plate heat exchanger designed as a condenser, so that the solubility of a gas in it is lowest.

[0012] In a preferred embodiment, the gas separator is provided with a flow deflector, an obstruction, and / or a flow retarder. Such structures, which mechanically influence the flow of the liquid and are expediently installed in a pipe or conduit section, are easy to install and still allow for effective gas separation. The flow deflector preferably causes a 180° reversal of the flow direction. In particular, the liquid flows geodesically upwards before the flow deflector and geodesically downwards after the flow deflection. Here, the terms "geodesically upwards" and "geodesically downwards" refer to the operational positioning of the plate heat exchanger.

[0013] In an advantageous embodiment, a separation chamber is provided in which the gas separated from the liquid collects. The separation chamber is expediently located in a geodetically upper region of the gas separator. The separation chamber can, in particular, be a section of the duct or pipe within which the liquid flows away from the outlet opening of the plate stack, preferably towards a building and the heating equipment installed in the building.

[0014] According to a preferred embodiment, the separation chamber of the gas separator is provided with a vent opening and an automatically acting valve that opens the vent opening when a sufficiently large gas bubble forms. A float valve with a float, for example a plastic ball, is suitable for this purpose. When the liquid level decreases, the float sinks and opens the vent opening above it. When the liquid level is sufficiently high, the float is pushed upwards and seals the valve.

[0015] Preferably, the separated gas is discharged to an outdoor area outside the building. If the gas separator is located outdoors, this can be done simply through the vent. If the gas separator is located partially or completely inside the building, the separated gas can be discharged to the outside via a pipeline.

[0016] According to the invention, a gas sensor is provided which is connected to the gas separator. The gas separator and gas sensor should be designed and arranged such that the separated gas is directed to the gas sensor, for example, by rising upwards and / or being forced into the gas separator by the liquid. The gas sensor should preferably be designed to be sensitive to the gas used as a refrigerant. If the refrigerant is propane, then the gas sensor should be a propane sensor.

[0017] Preferably, the gas sensor is equipped with an electrical signal output. The signal generated by the gas sensor can be used in any way to trigger an alarm and / or to stop the heating or cooling system. If gas enters the heating water due to a leak in the plate heat exchanger, it is detected by the gas sensor as it exits the plate heat exchanger, and a response can be initiated without human intervention.

[0018] According to a further aspect of the invention, a heating or cooling system for a building is provided. The heating or cooling system comprises a heat pump or refrigeration system with at least one plate heat exchanger according to one of the embodiments described herein. The plate heat exchanger is configured to heat the heating water. The heating or cooling system further comprises a water supply line connected to the plate heat exchanger, which is configured to direct the water from the outlet opening into the building.

[0019] Depending on whether it is a heating or cooling system, the fluid, in this case water, can be referred to as heating water or cooling water, which is directed into the building via a hot water inlet or a cooling water inlet to supply the heating or cooling system.

[0020] To prevent gas escaping from the gas separator from entering the building, the plate heat exchanger, i.e. the plate stack and the gas separator, is preferably located outside the building.

[0021] Alternatively, the stack of plates and the gas separator can be located inside the building. In this case, a pipe is provided through which the separated gas is carried out of the building.

[0022] According to a further embodiment, the heating or cooling system can be used reversibly. In this case, the stack of plates is used as a condenser and / or as an evaporator.

[0023] According to a further aspect of the invention, the gas separator according to one of the embodiments described above or below can also be retrofitted to plate heat exchangers, i.e., after the plate heat exchanger has already been installed in the heating or cooling system. Such a retrofit can serve to make the plate heat exchanger safer.

[0024] Advantageously, a gas separator equipped with a gas sensor can also be used to perform a leak test on the plate heat exchanger. It is irrelevant whether the secondary flow channels are filled with gas or another liquid. A test gas, to which the gas sensor is sensitive, can be added to the gas or other liquid. If this test gas enters the primary flow channels from the secondary flow channels due to a leak, it is separated from the liquid and detected by the gas sensor.

[0025] If the second flow channels are traversed by the gas, then it is advantageous if the test gas and the gas sensor are selected in such a way that the gas sensor detects the test gas but not the gas flowing through it.

[0026] The invention is explained below with reference to exemplary embodiments and the figures. These show: Fig. 1 is a schematic cross-sectional view of a gas separator connected to a plate stack of a plate heat exchanger according to a first embodiment; Fig. 2 is a schematic cross-sectional view of a gas separator connected to a plate stack of a plate heat exchanger according to a second embodiment; and Fig. 3 is a schematic cross-sectional view of a gas separator connected to a plate stack of a plate heat exchanger according to a third embodiment.

[0027] In the Fig. 1 A gas separator 3 is shown, which is connected to an outlet 2 of a plate stack 1. The plate stack 1, which is operated as part of a plate heat exchanger in a heat pump or refrigeration system, has first flow channels for heating water and second flow channels for propane, which is used here as a refrigerant. The heating water, heated in the plate stack, exits from the outlet 2 and flows through the gas separator 3 from the outlet 2 to a separator outlet 8, whereby the flow cross-section is at least doubled. A wall in the gas separator 3 forms an obstruction 4, which here acts as a flow deflector.

[0028] Should propane be present in the heating water in the form of bubbles, particularly due to a leak within the plate stack 1, then the obstruction 4 causes the propane to be forced out of the heating water, pass through a vent opening 7, and collect in a separator chamber 5 above the flow. The heating water has its highest temperature directly at the outlet opening 2, so the propane gas dissolved in the heating water is separated more easily than if the gas separator 3 were located further downstream of the outlet opening 2 along a pipe.

[0029] A float valve, for example a valve in the form of a floating ball 71, prevents heating water from entering the cavity 61. When propane passes through the vent openings 7 and accumulates in the separator chamber 5, this causes the liquid level in the separator chamber 5 to drop. The ball 71, floating on the heating water, then also sinks, creating an opening to the cavity 61. The propane then enters the cavity 61 and can escape from there through gas outlet holes 63 in the form of bores.

[0030] The heating water, now free of propane gas, flows through the separator outlet 8 into a pipe (not shown), which is connected to the separator outlet 8 of the gas separator 3 via a pipe connection 81. The pipe transports the heating water to a heating appliance or appliances, which may be located in a building.

[0031] An alternative design of a gas separator 3 is described in the Fig. 2 This differs from the embodiment shown. Fig. 1 that a gas sensor 6 is arranged in the cavity 61. The separated propane gas can enter the cavity 61 of the gas sensor 6 through the float valve 71 and be detected by the gas sensor 6, which is designed as a propane sensor, before escaping to the outside through the gas outlet holes 62. The gas sensor 6 is equipped with an electrical signal output. The signal generated by the detection of the propane gas can be used in any way to trigger an alarm or to stop the system.

[0032] Finally, in the Fig. 3 A third possible design of the gas separator is shown. It differs from the design according to Fig. 2This is achieved by placing a permeable film 63 between the valve 71 and the cavity 61. The permeable film 63 is impermeable to water and allows only the gas separated from the heating water to pass into the cavity 61. This prevents the sensitive gas sensor 6 from coming into contact with water. Reference symbol list:

[0033] 1. Stack of plates 2. Liquid outlet 3. Gas separator 4. Flow deflection / obstruction / flow delay 5. Separation chamber 6. Gas sensor 6. Cavity 6. Gas outlet holes 6. Permeable film 7. Vent opening 7. PVDF sphere 8. Separator outlet 8. Pipe connection

Claims

1. A plate heat exchanger having a plate stack (1) of heat transfer plates stacked on top of each other, which are profiled in such a way that first flow channels for a liquid and second flow channels for a gas are formed between them, wherein during operation between the liquid and the gas a heat exchange takes place through respective heat transfer plates, wherein a gas separator (3) is arranged at an outlet opening (2) of the plate stack (1) for liquid, which is designed to separate the gas carried by the liquid due to a leak within the plate heat exchanger from the liquid, wherein a liquid inlet opening is provided in such a way that the liquid enters the plate stack through the liquid inlet opening and exits it through the outlet opening, characterized by a gas sensor (6) connected to the gas separator (3).

2. The plate heat exchanger according to claim 1, characterized in that the gas separator (3) has a flow deflection (4), an obstacle (4) and / or a flow delay (4).

3. The plate heat exchanger according to claim 1 or 2, characterized in that a separation chamber (5) is provided in which the gas separated from the liquid collects.

4. The plate heat exchanger according to claim 3, characterized in that a vent opening (7) is provided at the separation chamber (5) of the gas separator (3).

5. A heating or cooling system for a building comprising a heat pump or cooling system having at least one plate heat exchanger in according to any one of preceding claims for heating of water and a water inlet connected to the plate heat exchanger, which is designed to conduct the water from the outlet opening (2) into the building.

6. A building having a heating or cooling system according to claim 6, characterized in that the plate stack (1) and the gas separator (3) are designed to be arranged outside the building.

7. A building having a heating or cooling system according to claim 6, characterized in that the plate stack (1) and the gas separator (3) are designed to be arranged in the building, wherein a line is provided by which the separated gas is led out of the building.

8. A heating or cooling system or building according to any one of claims 5 to 7, characterized by reversible usability, wherein the plate stack (1) is used as a condenser and / or as an evaporator.

9. A building having a heating or cooling system according to any one of claims 6 to 9, having a plate heat exchanger according to claim 3, characterized in that the separation chamber (5) is arranged in a geodetic upper area of the gas separator (3).

10. A method, comprising following method steps: - providing a plate heat exchanger having a plate stack (1) of heat transfer plates stacked on top of each other, which are profiled in such a way that the first flow channels for a liquid and second flow channels for a gas or for another liquid are formed between them, wherein a heat exchange takes place between the liquid and the gas or between the liquid and the further liquid through respective heat transfer plates during operation, wherein a liquid inlet opening is provided in such a way that the liquid enters the plate stack through the liquid inlet opening and exits it through the outlet opening, - arranging a gas separator (3) having a gas sensor (6) connected to the gas separator (3) at an outlet opening (2) of the plate stack (1) for the liquid, wherein the gas separator (3) is designed to separate gas carried by the liquid due to a leak within the plate heat exchanger from the liquid.

11. The method according to claim 10, characterized in that the gas separator is connected to a gas sensor, wherein a test gas to which the gas sensor is sensitive is introduced into the second flow channels, and wherein a detection of the test gas by the gas sensor is taken as an indication that the plate heat exchanger has a leakiness.