EP3087330A1

EP3087330A1 - Heat engine and method for operating a heat engine

Info

Publication number: EP3087330A1
Application number: EP15704258.1A
Authority: EP
Inventors: Vladimir Danov; Florian REISSNER
Original assignee: Siemens AG
Current assignee: Siemens AG
Priority date: 2014-02-11
Filing date: 2015-02-04
Publication date: 2016-11-02
Also published as: WO2015121116A1; CN106068428A; KR20160119229A; US20170167763A1; CA2939132A1; DE102014202429A1; JP2017508943A

Abstract

The invention relates to a heat engine (1) having a circuit system (2) which conducts a fluid (16) and which has at least one evaporation device (3) by means of which the fluid (16) can be evaporated, having at least one compression device (4) by means of which the fluid (16) can be compressed, having at least one condensation device (5) by means of which the fluid (16) can be condensed, having an accumulation device (6) by means of which the fluid (16) and a further fluid (17), which can be added to the fluid (16) by means of the compression device (4), can be accumulated, and having at least one expansion device (7) by means of which the fluid (16) can be expanded. The accumulation device (6) comprises a mixing device (8) by means of which the fluid (16) and the further fluid (17) can be mixed to form an emulsion. The invention also relates to a method for operating a heat engine (1) of said type.

Description

description

Power heating machine and method for operating a power-heating machine

The invention relates to a power heating machine with a fluid-carrying circulation system with at least one evaporation device, by means of which the fluid is vaporized, with at least one compression device, by means of which the fluid is compressible, with at least one condensation device, by means of which the fluid is condensable, with a collecting device by means of which the fluid and a fluid which can be added to the fluid by means of the compression device can be collected, and with at least one expansion device, by means of which the fluid is expandable. The invention also relates to a method for operating such a power heating machine.

In combined heat and power plants, which include heat pumps and chillers, heat energy is increased from a lower temperature level to a higher temperature level using mechanical energy. In both chillers and heat pumps, oil-lubricated compressors are commonly used to compress a fluid. After compressing and condensing the fluid in a condenser, oil separators are used which separate oil emerging from a compressor or other compressor from the fluid, with the entrained oil subsequently being fed back into the compressor. Complete separation is generally not possible, so that part of the entrained oil also enters a condenser of the chiller or heat pump. Especially for larger systems (> 20 kW), a collector is installed after the condenser. This serves to buffer the fluid and the oil contained therein, so that liquid fluid always passes into an expansion valve connected downstream of the collector in the fluid flow direction (expansion device). The collector can also be used to monitor operating fluctuations, load changes or temperatures. temperature changes are buffered on the heat source or heat sink side of the power heater. Such a collector is particularly necessary for systems with multiple evaporators.

However, the fluid used in the respective power plant should, in addition to other physical properties, have a density that is appropriate in comparison to the oil (compressor oil), and should be further miscible with the oil. This avoids that the fluid, for example, a larger

Density than the oil has, and thus the oil floating in the collector, collect in the long term there and would not get back into the compressor. By using fluids (eg R134a) which are miscible with the compressor oil, floating oil is dissolved in the fluid and can flow with the fluid to the expansion valve.

Object of the present invention is to provide a force heat engine of the type mentioned, and to provide a method for operating such a power heat engine, in which even at high densities of the fluids used in the power heat engine and their immiscibility is a particularly trouble-free operation. This task is accomplished by a power heater with the

Features of claim 1 and solved by a method having the features of claim 9. Advantageous embodiments with expedient developments of the invention are specified in the dependent claims.

In order to be able to use such fluids in the power heating machine, which have large density differences from one another and additionally or alternatively immiscibility to one another, it is provided according to the invention that the collecting device comprises a mixing device, by means of which the fluid and the further fluid can be mixed to form an emulsion are . The use of such a mixing device produces as homogeneous a mixture as possible between the fluid used in the power heat engine, which serves as working fluid and the further fluid excreted, for example, by the compression device (eg compressor), which is formed, for example, as compressor oil. Thus, a particularly even distribution of the further fluid in the fluid is achieved by means of the mixing device, even if the fluid and the further fluid differ significantly from one another in terms of their density, ie the fluid has a significantly higher or lower density than the further fluid, or Even if the other fluid is not miscible with the fluid. In other words, the fact that the collecting device comprises the mixing device makes it possible to produce an emulsion of the disperse phase (further fluid) and the continuous phase (condensed and thus liquid fluid). By preparing this emulsion finely dispersed oil droplets of the compressor oil can get along with the fluid to the expansion valve, which is particularly effective even with significant differences in density between the fluid and the other fluid, a homogeneous distribution of the two fluids is achieved in the emulsion. Thus, therefore, on the one hand concentration-related fluctuations in operation due to poor, or inhomogeneous mixing of the fluid with the other fluid of the power heater, as well as a lubricant sub-supply of the compressor (compressor) can be largely avoided. In an advantageous embodiment of the invention is the

Mixing device arranged in the fluid flow direction in front of the collecting device.

By connecting the mixing device upstream of the collecting device, the fluid leaving the condensation device (condenser) and the further fluid are passed on to the collector as a particularly homogeneous emulsion. As a further advantage, it has been shown that the further fluid is formed as a compressor oil.

The homogeneous mixture of the fluid with the other fluid (compressor oil) ensures particularly far-reaching that a lubricant undersupply of the compressor (the compressor) is avoided. In other words, therefore, a particularly uniform lubrication of the compressor is ensured by the homogeneously distributed in the fluid compressor oil.

It is a further advantage if the mixing device has a stirrer which is designed as a static mixer.

A stirrer is a particularly inexpensive and efficient way of mixing the fluid with the further fluid to form an emulsion, especially when the stirrer is designed as a static mixer. The static mixer consists of flow influencing, e.g. a screw-forming elements which divide the fluid flow alternately and then merge again. In other words, therefore, their mixing is effected in a particularly efficient manner by the flow movement of the fluid and of the further fluid, and accordingly a particularly homogeneous emulsion with a particularly uniform distribution of very small drops of the further fluid in the fluid is produced. The mixing device is e.g. formed as the recorded in a pipe piece static stirrer.

In a further advantageous embodiment, the collecting device has a magnetic stirrer.

Such a magnetic stirrer can be made particularly compact and thus be used in a particularly small space for the formation of the emulsion of the fluid and the other fluid. As further advantageous, it has been shown that the magnetic stirrer has a plurality of metallic wings.

Through the use of metallic wings, the additional fluid is distributed particularly rapidly and particularly homogeneously in the fluid, wherein the magnetic stirrer and the metallic wings can approach, for example, to the edge of the collector and thus a particularly intensive stirring or circulating the mixture of the fluid and the further fluid can be achieved. In other words, the metallic vanes are particularly simple and efficient turbulence generators for producing the homogeneous mixture in the form of the emulsion. It has also proven to be advantageous if the collecting device has a magnetic coil arranged at its edge region, by means of which the magnetic stirrer can be rotated , By means of the magnetic coil, the magnetic stirrer can be rotated without contact, wherein a complex coupling of the magnetic stirrer with a mechanical drive unit, such as an electric motor, as well as a seal of respective coupling elements, for example, drive shafts, compared to a fluid outlet is superfluous. The border area corresponds to e.g. the outer wall (or outer circumferential surface) of a container receiving the fluid and the further fluid, which is e.g. is designed as a collector and in which the magnetic stirrer is received.

In a further advantageous embodiment of the invention, the collecting device on a collector, which is formed of a non-magnetic material. The collector corresponds to a receptacle of the collecting device in which the fluid and the further fluid emerging from the condensation device are collected and buffered for further use. If the collector is made A non-magnetic material (eg, non-magnetic stainless steel) is formed, and a magnetic stirrer which is driven by a solenoid can be used particularly efficiently and without interference (by the collector) of a magnetic field constituted by the magnetic coil.

In the inventive method for operating a

Kraftwärmemaschine with a fluid, this fluid is evaporated by means of at least one evaporation device, compressed by means of a compression device, condensed by means of at least one condensation device and collected by a collector comprising a collector together with a fluid added to the fluid by means of the compression device further fluid, and the fluid by means of a Ex- expansion facility expands. The collecting device comprises a mixing device for mixing the fluid with the further fluid to form an emulsion.

By forming the most homogeneous emulsion of the fluid and the other fluid are concentration-related

Operating fluctuations of the power heat engine particularly largely prevented, in addition, a particularly uniform and continuous lubricant supply of the compression device is ensured.

The advantages and preferred embodiments described for the power heat engine according to the invention also apply to the method according to the invention and vice versa. The features mentioned above in the description and

Combinations of features as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures can be used not only in the respectively specified combination but also in other combinations or alone, without departing from the scope of the invention. Further advantages, features and details of the invention will become apparent from the claims, the following description of preferred embodiments and with reference to the figures. FIG. 1 is a schematic diagram of a heat pump cycle system as an example of a cogeneration machine, wherein a prior art collector is used to collect a fluid and another fluid which is formed as compressor oil; FIG.

2 shows a known from the prior art embodiment, wherein for emptying of the collector, a hot gas bypass leads from a pressure side of a compression device formed as a compressor in the collector; 3 shows a schematic representation of a circulatory system of a present invention as a heat pump force heat engine, wherein a collecting means of the power plant has a designed as a static mixer mixing means according to the invention, by means of which an emulsion of the fluid and the other fluid can be produced; a further schematic representation of another embodiment of the collecting device, wherein the mixing device according to the invention in this case comprises a magnetic stirrer with metallic wings and arranged on an edge region of the collecting means magnetic coil.

1 shows a schematic representation of a power heating machine 1, which is presently designed as a heat pump. In the power heating machine 1 forms an evaporator formed evaporation device 3 together with a designed as a compressor or compressor compression device 4, as well as with a condenser formed as a condenser 5 and an expansion valve as expansion device 7 a circulatory system 2. The circulatory system 2 includes a not further illustrated piping system in which a Fluid 16 is guided. The fluid 16 corresponds to a fluid used in the power heat engine 1, which is subjected to evaporation, compression, condensation and subsequent expansion. Usually there is a separation of a further fluid 17 from the compression device 4 during operation thereof. This additional fluid 17 in this case corresponds to compressor oil, which as

Lubricant is used to maintain trouble-free operation of the compression device 4. The departure of the other fluid 17 (compressor oil) in the

Circulation system 2 of the power heating machine 1 is not desirable, but can not be completely avoided. The fluid 16 and the additional fluid 17 added to the fluid 16 by means of the compression device 4 are moved in the circulatory system 2 of the power heating machine 1 in accordance with a fluid flow direction 10 illustrated with an arrow. In order to avoid a supply of lubricating oil to the compression device, ie the compressor or compressor, the power heating machine 1 comprises a collecting device 6 with a collector 9. The collector 9 serves to buffer the fluid 16, so that always fluid fluid 16 in the expansion valve, so the Expansion device 7, passes. This is also ensured in the case of operating fluctuations, load changes or temperature changes on the heat source or heat sink side of the power heat engine 1, provided that the fluid 16 and the further fluid 17 are miscible with each other and the fluid 16 has a lower or equal density than the further fluid 17 , Only then is it ensured that the further fluid 17 does not float up in the collector 9 (on the fluid 16), but via the expansion device 7 back to the compressor. processing device 4 passes. In order to ensure a trouble-free operation of the power heating machine 1 according to the known from the prior art embodiment in Figure 1, so the fluid used 16 should have a lower density than the other fluid 17 (compressor oil). Is this the

Case, the other fluid 17 flows by itself in the collector 9 down to the expansion device 7, ie to the expansion valve. Thus, according to the prior art, it is necessary to use fluids 16 (e.g., R134a) which are miscible with the further fluid 17. Due to the miscibility floating compressor oil is dissolved in the fluid 16 and can flow with this to the expansion valve.

The figures described below also contain features which have already been explained with reference to FIG. 1, for which reason they will not be discussed again below.

FIG. 2 shows, with reference to a further schematic representation of the power heating machine 1, a hot gas bypass 18 which connects one pressure side of the compression device 4 to the collector 9. The pressure side corresponds to a point in the circulation system 2 in the fluid flow direction 10 behind the compression device 4 and before the condenser 5. As a result of a direct fluid vapor loading with the compressed fluid 16 and the entrained therein further fluid 17 (compressor oil), the mixture contained in the collector 9 from the fluid 16 and the further fluid 17 is emptied according to a direction indicated by an arrow 19, and subsequently the further fluid 17, which is separated from the fluid 16, in turn fed to the compression device 4. While the hot gas bypass 18 is active and accordingly the compressed mixture of the fluid 16 and the further fluid 17 is conveyed from the pressure side of the compression device 4 into the collector 9, no condensation takes place and thus no heat emission. In other words, during the emptying of the collector 9 as a result of the fluid vapor admission by means of the hot gas bypass 18, the condensation device 5, so the capacitor, shut down. Accordingly, respective lines 20, by means of which the condensation device 5 is connected to the compression device 4 or to the collecting device 6, are not flowed through by the mixture of the fluid 16 and the further fluid 17 during the fluid vapor application. This solution is very cumbersome and inefficient, since despite the compression device 4 is running no heat through the condensation device 5 and on the other hand, equipped with the hot gas bypass 18 Kraftwärmemaschine 1 requires a high maintenance and control effort. The control effort is increased, for example, because it is to monitor when the collector 9 is emptied and accordingly the Fluiddampfbeaufschlagung in the deflated state ends again and thus the condensation device 5 can be flowed through. The emptying of the collector 9 is to be monitored in particular because there is a risk of high temperature exposure of the collector 9 when it is empty for a long period of time.

The embodiments known from the prior art are unsuitable as soon as a fluid having a higher density than the further fluid 17 (compressor oil) and additionally or alternatively immiscibility with the further fluid 17 is used as the fluid 16, since then a recycling the further fluid 17 to the compression device 4 can not be ensured.

In order to be able to use such operating means as the fluid 16, which has a higher density than the further fluid 17, which in the present case corresponds to a compressor oil, or immiscibility with the further fluid 17, embodiments are as described below with reference to FIG. 3 and FIG 4 are particularly suitable.

In the exemplary embodiments shown in FIG. 3 and FIG. 4, the collecting device 6 comprises a mixing device 8, by means of which the fluid 16 and the other Fluid 17 are mixable into an emulsion. The mixing device 8 shown in FIG. 3 has a stirrer 11 designed as a static mixer, which is arranged in front of the collecting device 6 in the direction of fluid flow. In other words, therefore, the fluid 16 emerging from the condensation device 5 and the further fluid 17 by means of the mixing device 8 become an emulsion of a disperse phase consisting of the further fluid 17 (compressor oil) and a continuous phase consisting of the resulting the previous condensation liquid fluid 16 stirred. The oil droplets of the further fluid 17 are therefore distributed particularly finely by means of the mixing device 8 in the fluid 16. In this state, the finely divided oil droplets are forwarded together with the fluid 16 to the expansion valve, that is, to the expansion device 7. The mixing device 8 can be designed to be particularly simple and accordingly comprise a straight piece of pipe in which the stirrer 11 rotates according to a rotational movement 21 marked by an arrow. In order to achieve a distribution of particularly fine oil droplets (of the further fluid 17) in the working fluid (fluid 16), a more or less pronounced distribution, and consequently a more or less strong stirring, is dependent on the subsequent residence time of the emulsion in the collector 9 required by the stirrer 11 of the mixing device 8.

In the exemplary embodiment shown in FIG. 4, it is provided in the power heat engine 1 that the collecting device 6 has a magnetic stirrer 12 with a plurality of metallic wings 13. Furthermore, the collecting device 6 has a magnetic coil 15 arranged at its edge region 14, by means of which the magnetic stirrer 12 is rotatable in accordance with the rotational movement 21. In the present case, the edge region 14 corresponds to the outer surface of the container wall of the collector 9. The magnetic stirrer 12 is installed in the collector 9, that is to say the container or storage container, and is rotated by a traveling field of the magnetic coil 15. To a drive of the magnetic stirrer 12 by means of the magnetic coil 15th to ensure the collector 9 is formed of a non-magnetic material.

The embodiment presented in FIG. 3 does not require any additional components, such as, for example, the magnetic coil 15, but reaches its limits for collectors 9, in which the emulsion is to be stored over a longer residence time. In order to prevent segregation of the two fluids 16, 17 even at longer residence times of the emulsion from the fluid 16 and the further fluid 17, the basis of

FIG 4 presented embodiment with the magnetic coil 15 is particularly suitable.

In the mixing device 8, an active mixing of the two fluids 16, 17 is therefore desired by means of the stirrer 11. Due to the formation of emulsions by means of the mixing device 8, fluids 16 can be used independently of their density and their mixing behavior with the respective further fluid 17 in the power heating machine 1, whereby an interruption of the heat output at the condensation device 5 or complex maintenance work is omitted.

Claims

claims

1. A power heat engine (1) with a fluid (16) leading circuit system (2) with at least one Verdampfungseinrich- device (3), by means of which the fluid (16) is evaporable, with at least one compression device (4), by means of which the fluid (16) is compressible, with at least one condensation device (5), by means of which the fluid (16) is condensable, with a collecting device (6), by means of which the fluid (16) and the fluid (16) by means of the compression device (4) zusetzbares, further fluid (17) is collectable, and with at least one expansion device (7) by means of which the fluid (16) is expandable,

characterized in that

the collecting device (6) comprises a mixing device (8), by means of which the fluid (16) and the further fluid (17) can be mixed to form an emulsion.

2. Power heating machine (1) according to claim 1,

characterized in that

the mixing device (8) is arranged in the fluid flow direction (10) in front of the collecting device (6).

3. power heating machine (1) according to claim 1 or 2,

characterized in that

the further fluid (17) is formed as a compressor oil.

4. Kraftwärmemaschine (1) according to one of claims 1 to 3, characterized in that

the mixing device (8) has a stirrer (11), which is designed as a static mixer.

5. Kraftwärmemaschine (1) according to one of claims 1 to 3, characterized in that

the collecting device (6) has a magnetic stirrer (12).

6. power heater (1) according to claim 5, characterized in that

the magnetic stirrer (12) has a plurality of metallic vanes (13).

7. power heating machine (1) according to claim 5 or 6,

characterized in that

the collecting device (6) has a magnetic coil (15) arranged at its edge region (14), by means of which the magnetic stirrer (12) is rotatable.

8. Kraftwärmemaschine (1) according to one of claims 1 to 7, characterized in that

the collecting device (6) has a collector (9) which is formed from a non-magnetic material.

9. A method of operating a power heating machine (1) comprising the steps of:

Vaporizing a fluid (16) by means of at least one evaporation device (3),

Compacting the fluid (16) by means of at least one compression device (4),

Condensing the fluid (16) by means of at least one condensation device (5),

Collecting the fluid (16) and a further fluid (17) added to the fluid by means of the compression device (4) by means of a collecting device (6) comprising a collector (9), and

Expanding the fluid (16) by means of an expansion device (7)

characterized in that

the collecting device (6) comprises a mixing device (8) for mixing the fluid (16) with the further fluid (17) to form an emulsion.