Heat pump and its operating method

Abstract

The present invention relates to a heat pump (1) including a working fluid circuit, wherein the working fluid circuit comprises an evaporator (2) having a liquid receiving volume section (13) in a lower region and a vapor receiving volume section (14) in an upper region, a compressor (3) following the evaporator (2), a condenser (4) following the compressor (3), and an expansion unit (6) following the condenser (4) and connected to the evaporator (2), characterized in that the conduits (11, 12) connecting the expansion unit (6) to the evaporator (2) are guided through the vapor receiving volume section (14) of the evaporator (2) before opening into the evaporator (2). Furthermore, the present invention relates to a method for operating such a heat pump (1).

Description

Technical Field

[0001] Heat pump and operation method thereof

[0002] The present invention relates to a heat pump including a working fluid circuit, the working fluid circuit having an evaporator that forms a liquid receiving volume in a lower region and a vapor receiving volume in an upper region, a compressor downstream of the evaporator, a condenser downstream of the compressor, and an expansion vessel downstream of the condenser and connected to the evaporator, wherein a plurality of throttle valves are provided in a conduit that connects the condenser to the expansion vessel and further connects the expansion vessel to the evaporator. Furthermore, the present invention relates to a method for operating such a heat pump.

[0003] Heat pumps of the type mentioned at the outset are known in various configurations from the prior art. They comprise a working fluid circuit which, as main components, has an evaporator, a compressor, a condenser and an expansion unit. In the evaporator, the working fluid is heated by an external heat source and evaporates. Thereafter, it is supplied to the compressor, where it is brought to a high pressure level. Subsequently, the working fluid is liquefied in the condenser at a liquefaction temperature increased above the evaporation temperature. In order to bring the working fluid back to the starting state again at the end of the circuit, it is expanded in the expansion unit, as a result of which its temperature drops again.

[0004] Inside the evaporator, together with the vapor flow generated therein, a plurality of small liquid droplets may be entrained and supplied to the compressor. If these droplets are too large, they may cause damage to the compressor. To avoid such damage, it has already been proposed to arrange a demister in the vapor receiving volume of the evaporator, which demister separates droplets from the vapor mass flow, after which these droplets return to the liquid receiving volume of the evaporator and drip down.

Summary of the Invention

Problem to be Solved by the Invention

[0005] Starting from this prior art, the object of the present invention is to provide a heat pump having an alternative structure in the type of heat pump described at the beginning, and an alternative method for operating such a heat pump. [Means for solving the problem]

[0006] To solve this problem, the present invention provides a heat pump including a working fluid circuit, the working fluid circuit having an evaporator having a liquid receiving volume in a lower region and a vapor receiving volume in an upper region, a compressor following the evaporator, a condenser following the compressor, and an expansion unit following the condenser and connected to the evaporator, wherein the conduit connecting the expansion unit to the evaporator is guided through the vapor receiving volume of the evaporator before opening into the evaporator. Thanks to such a structure, the working fluid guided from the expansion unit to the evaporator can be used to superheat the vapor contained in the vapor receiving volume of the evaporator, thereby evaporating droplets contained in the vapor and preventing them from reaching the compressor. On the one hand, the heat pump according to the present invention is characterized by the complete omission of placing a demister in the evaporator. On the other hand, since further heat is removed from the working fluid that was previously only expanded along the path from the expansion unit to the evaporator, the coefficient of performance (COP) of the heat pump can be improved by about 5 to 7%.

[0007] Preferably, the conduits connecting the expansion unit to the evaporator are formed as a bundle of conduits or as meandering conduits in the region guided through the vapor receiving volume of the evaporator, thereby allowing heat to be released as uniformly as possible and / or over as wide an area as possible from the vapor-like working fluid.

[0008] According to one embodiment of the present invention, the expansion unit comprises one throttle valve, one expansion vessel located downstream of the throttle valve and forming a liquid receiving volume section and a vapor receiving volume section, and a further throttle valve located downstream of the expansion vessel. Accordingly, the pressure of the condensed working fluid coming from the condenser can first be reduced to a first pressure level by the first throttle valve, at which pressure the working fluid is stored in the expansion vessel in both liquid and gaseous forms. Then, by using the further throttle valve, the pressure of the working fluid can be reduced to a second pressure level before it enters the evaporator.

[0009] Advantageously, the demister is positioned within the vapor receiving volume of the expansion vessel, and a conduit connecting the expansion vessel to the compressor is led out from the expansion vessel above the demister. Accordingly, the vaporized working fluid contained in the expansion vessel can be led directly to the compressor without having to pass through an evaporator, thereby improving the performance coefficient of the heat pump.

[0010] Preferably, the vapor receiving volume section of the evaporator and the condenser are connected to each other by a bypass conduit equipped with a bypass valve. Accordingly, the compressor can be bypassed as needed.

[0011] Furthermore, in order to solve the problems described at the beginning, the present invention provides a method for operating a heat pump, in particular a heat pump in which a working fluid circulates, the method being characterized in that the working fluid vapor present in the vapor receiving volume of the heat pump's evaporator is superheated by heat exchange with the working fluid condensate introduced from the heat pump's expansion unit to the evaporator, and then introduced to the heat pump's compressor.

[0012] Further features and advantages of the present invention will become apparent from the following description with reference to the attached Figure 1. [Brief explanation of the drawing]

[0013] [Figure 1]A schematic diagram of a heat pump according to one embodiment of the present invention is shown. In the following, the same reference numerals indicate the same or similar components. [Modes for carrying out the invention]

[0014] The heat pump 1 shown in the drawing includes a working fluid circuit, which comprises an evaporator 2, a compressor 3, a condenser 4, a basically optional subcooler 5, and an expansion unit 6, all of which are connected to each other by corresponding conduits 7, 8, 9, 10, 11, and 12. The evaporator 2 has a liquid receiving volume 13 in its lower region, through which conduits 12 open, and a vapor receiving volume 14 in its upper region, at which conduit 7 is led out from the evaporator 2. Multiple pipes 15 are arranged within the liquid receiving volume 13, through which a warm medium from an external heat source is introduced. In this case, the medium is supplied via conduit 16 and discharged via conduit 17. In this embodiment, a conduit bundle 18 connecting conduits 11 and 12 is arranged within the vapor receiving volume 14 of the evaporator 2. During operation of the heat pump 1, the working fluid that circulates in the working fluid circuit is introduced through this bundle, which will be described in detail below. These conduits 11 and 12, as well as the conduit bundle 18, can also be replaced, for example, by a single conduit that meanders through the vapor receiving volume section 14 of the evaporator 2, but is not shown in this embodiment. In the illustrated embodiment, the compressor 3, driven by an electric motor 19, has two compression stages 20 and 21, through which the working fluid passes sequentially. However, it is clear that a single-stage compressor can be used, and a compressor with more than two compression stages can also be used. In this embodiment, the condenser 4 and the supercooler 5 each have a number of pipes 22 through which the medium to be heated by the heat pump 1 is led, which in this embodiment is first supplied to the supercooler 5 via conduit 23, then led out of the supercooler 5 via conduit 24 and supplied to the condenser 4, and finally discharged from the condenser 4 via conduit 25. In the illustrated embodiment, the expansion unit 6 includes one throttle valve 26, one expansion container 27 located downstream of the throttle valve 26 and forming a liquid receiving volume section 28 and a vapor receiving volume section 29, and another throttle valve 30 located downstream of the expansion container 27. In this embodiment, the throttle valve 26 is located in the conduit 10 and the throttle valve 30 is located in the conduit 12.In this embodiment, the conduit 10 opens into the steam receiving volume section 29, and the conduit 11 is connected to the liquid receiving volume section 28. A demister 31 is located in the steam receiving volume section 29 of the expansion vessel 27, and a conduit 32 connecting the expansion vessel 27 to the compressor 3 is led out from the expansion vessel 27 above the demister 31. Furthermore, in the illustrated embodiment, the steam receiving volume section 14 of the evaporator 2 and the condenser 4 are connected to each other by a bypass conduit 34 equipped with a bypass valve 33.

[0015] During operation of the heat pump 1, the working fluid circulating in the heat pump 1's working fluid circuit, which is usually a refrigerant, is first heated in the evaporator 2 by heat exchange with a warm medium flowing in from an external heat source. This warm medium is supplied to the evaporator 2 via conduit 16, then guided through several pipes 15 located within the liquid receiving volume section 13 of the evaporator 2, and then discharged again from the evaporator 2 via conduit 17. This working fluid evaporates and rises to the vapor receiving volume section 14 of the evaporator 2, where it is superheated by the liquid working fluid guided through a conduit bundle 18 located within the vapor receiving volume section 14. This superheating removes all droplets contained in the vapor working fluid. The pure vapor is then guided through conduit 7 to the compressor 3, where it is compressed in two stages, and then supplied to the condenser 4 via conduit 8, still in vapor form. Inside the condenser 4, this vapor condenses by heat exchange with a medium to be heated, guided through pipes 22 located within the condenser 4. The working fluid, in liquid form, exits the condenser 4 via conduit 9 and is supplied to the supercooler 5, where its temperature is further reduced by heat exchange with the medium to be heated. The working fluid flows out of the supercooler 5 via conduit 10, is throttled by throttle valve 26, and is then supplied to the expansion vessel 27 in a two-phase state. Its liquid phase collects in the liquid receiving volume 28 of the expansion vessel 27, and its vapor phase collects in the vapor receiving volume 29 of the expansion vessel 27. The vaporized working fluid passes through the demister 31 and is supplied directly back to the compressor 3 via conduit 32. The liquid working fluid is guided via conduit 11 to a tube bundle 18 located in the vapor receiving volume 14 of the evaporator 2, exits the evaporator 2 in liquid form via conduit 12, is throttled again using throttle valve 30, and is finally supplied to the liquid receiving volume 13 of the evaporator 2. Selectively, the vaporized working fluid from the vapor receiving volume section 14 of the evaporator 2 may be supplied directly to the condenser 4 via the bypass conduit 34.

[0016] Although the present invention has been illustrated and described in more detail with reference to preferred embodiments, the present invention is not limited to the disclosed examples, and other modifications can be derived therefrom by those skilled in the art without departing from the scope of protection of the present invention.

[0017] Regardless of the grammatical gender of a particular term, this includes men, women, or persons with other gender identities.

Claims

1. A heat pump (1) including a working fluid circuit, In a heat pump having a working fluid circuit comprising: an evaporator (2) having a liquid receiving volume section (13) in the lower region and a vapor receiving volume section (14) in the upper region; a compressor (3) connected to the evaporator (2); a condenser (4) connected to the compressor (3); and an expansion unit (6) connected to the condenser (4) and also connected to the evaporator (2), The conduits (11, 12) connecting the expansion unit (6) to the evaporator (2) pass through the vapor receiving volume section (14) of the evaporator (2) before reaching the evaporator (2). A heat pump (1) characterized by the following:

2. A heat pump (1) according to claim 1, A heat pump (1) characterized in that the conduits (11, 12) connecting the expansion unit (6) to the evaporator (2) are formed as a conduit bundle (18) or as meandering conduits in the region passing through the vapor receiving volume section (14) of the evaporator (2).

3. A heat pump (1) according to claim 1 or 2, The expansion unit (6) comprises one throttle valve (26), one expansion container (27) located downstream of the throttle valve (26) and forming a liquid receiving volume section (28) and a vapor receiving volume section (29), and another throttle valve (30) located downstream of the expansion container (6). A heat pump (1) characterized by having the following features.

4. A heat pump (1) according to claim 3, A demister (31) is positioned within the steam receiving volume (29) of the expansion vessel (27), and a conduit (32) connecting the expansion vessel (27) to the compressor (3) is led out from the expansion vessel (27) at the top of the demister (31). A heat pump (1) characterized by the following:

5. A heat pump (1) according to any one of claims 1 to 4, A heat pump (1) characterized in that the vapor receiving volume section (14) of the evaporator (2) and the condenser (4) are connected to each other by a bypass conduit (34) equipped with a bypass valve (33).

6. A method for operating a heat pump (1), particularly a heat pump according to any one of claims 1 to 5, in which a working fluid circulates inside, The vapor of the working fluid present inside the vapor receiving volume section (14) of the evaporator (2) of the heat pump (1) is superheated by heat exchange with the working fluid condensate that is guided from the expansion unit (6) of the heat pump to the evaporator (2). Subsequently, it is led to the compressor (3) of the heat pump (1), A method characterized by the following:

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