AT504564B1 - HEAT PUMP - Google Patents

Description

(19)

Austrian Patent Office (10) AT504 564B1 2008-09-15 (12) Patent specification (21) Application number: A 1941/2006 (51) Int. CI.8: F25B 1110 (2006.01) (22) Date of filing: 2006-11-23 (43) Published: 2008-09-15 AT504 564B1 2008-09-15

(54) HEAT PUMP (57) A heat pump circulates a working fluid and has one throttle (3) and two compressors (4, 5). In the direction of flow of the working medium (arrow 2), the throttle (3) with the first compressor (4) limits a low-pressure region, the first compressor (4) with the second compressor (5) a medium-pressure region and the second compressor (5) with the throttle ( 3) a high pressure area. Starting from at least one device (1, 7, 15) for providing thermal energy, a line (8, 9) for a heat-carrying medium to a heat exchanger (6) is arranged in the medium-pressure region.

The two compressors (4, 5) are powered directly via a photovoltaic element (1) with power. The resulting solar heat is supplied to a heat exchanger (6) in the medium-pressure region, whereby the pressure of the working medium increases and to the same extent the energy consumption of the second compressor (5) is reduced. DVR 0078018 (56) (73)

References: DE 278095C DE4415326C1 DE 10316165A1 US 2006 / 123838A1

Applicant: STOJEC MARIO PAUL A-9431 ST. STEFAN IM LAVANTTAL (AT) 2 AT 504 564 B1

The invention relates to a heat pump with two compressors and a throttle, which divide a circuit of a heat-carrying working medium in a low, medium and high pressure area, and with at least one heat exchanger, wherein between the two compressors of the medium-pressure region is limited and wherein in the medium-pressure region a heat exchanger is arranged.

Furthermore, the invention relates to a method for operating a heat pump, with which a working medium in a low-pressure region and a high-pressure region is brought to different temperature and pressure levels, wherein a medium-pressure region is formed by arranging two compressors.

The working principle of heat pumps and heat pumps for heating or cooling of buildings are known per se from the prior art. In this case, a working medium, such as a refrigerant, is alternately compressed by applying mechanical work, i. brought to a higher temperature level, and expanded with release of mechanical work, i. brought to a lower temperature level.

In such heat pumps, it is known to use a compressor to increase the temperature level, where the compressor separates a low pressure area ("cold side") and a high pressure area ("warm side"). To lower the temperature level, an expansion valve can be used, which also represents a second separation point between the cold and the warm side of the heat pump. The compressor work to bring the working fluid from a low to a high pressure, in the heat pump is a very energy-consuming process. A disadvantage of such heat pumps, however, that an increase in pressure of the working fluid before the compressor is not possible without the cooling capacity of the " cold side " to impair. Heat pumps with multi-stage compression are known from DE 278 095 C, US 2006/123 838 A1 and DE 44 15 326 C1. Furthermore, it is known from DE 103 16 165 A1 that the compressors can be supplied with power from a photovoltaic system.

The invention is based on the object to provide a heat pump and a method for operating such a heat pump available, with which the mentioned disadvantage is overcome and beyond further energy savings can be achieved.

This object is achieved according to the invention with a heat pump, which has the features of claim 1.

Furthermore, this object is achieved by a method having the features of claim 12.

Preferred and advantageous embodiments of the invention are subject of the dependent claims.

Due to the fact that, in the case of the heat pump according to the invention, a line for a heat-carrying medium to the heat exchanger in the medium-pressure region is arranged starting from at least one device for providing thermal energy, additional heat can be additionally supplied to the medium-pressure region without the cooling effect of the " cold side " is impaired, the energy balance of the heat pump is improved. The high and low pressure areas including the throttle can be designed as known from the prior art.

In a particularly preferred embodiment of the invention, it is provided that the first compressor is arranged between low-pressure and medium-pressure regions, and the second compressor is arranged between the medium-pressure and high-pressure regions. In addition, the first compressor is referred to as a medium-pressure compressor and the second compressor as a high-pressure compressor.

In the context of the invention, the feeding of further heat into the medium-pressure region on the one hand can take place in such a way that heat is returned from the high-pressure region into the medium-pressure region (preheating of the working medium). This is particularly advantageous when cooling the heat pump if the high pressure temperature is not needed for heating. Since, according to the invention, a heat exchanger is arranged in the medium-pressure region, the temperature of the working medium in the high-pressure region can be transmitted to the working medium in the medium-pressure region via this heat exchanger. The heat introduced into the medium pressure range increases the pressure of the working fluid. Thus, the heat recovery of the high-pressure compressor relieved and reduced its power consumption, which also improves the coefficient of performance of the heat pump. The reduction in power consumption is essentially proportional to how the pressure in the mid-pressure range increases by the supply of heat. Another benefit of energy recycling is that the excess heat does not have to be released to the environment.

In a preferred embodiment of the invention, temperatures which are between the temperatures in the low pressure range and the high pressure range, e.g. in the range of approx. 0 ° C to 100 ° C. This temperature range is designed so that directly into the medium pressure range thermal energy, i. Heat, from additional devices for providing energy, e.g. Photovoltaic or thermovoltaic elements, as well as energy from process or waste heat or from a cooling device, e.g. for cooling photovoltaic and / or thermovoltaic elements, can be fed, which continues to save considerable energy costs.

With the device for providing energy, such as the photovoltaic element, also the majority of the electrical energy can be generated for the two compressors themselves, the resulting solar heat can be used directly to increase the pressure of the working fluid in the medium pressure range.

By means of the two compressors of the heat pump according to the invention, therefore, an energy return and / or an additional energy supply in front of the high-pressure compressor is possible without negatively influencing the cooling capacity of the heat pump.

Further details Features and advantages of the invention will become apparent from the following description with reference to the accompanying drawings, in which a preferred embodiment is shown.

1 shows a flow chart of the heat pump according to the invention in the form of a refrigerating machine, and FIG. 2 shows an embodiment of the heat pump according to the invention in a schematic representation.

In Fig. 1, a highly simplified illustrated embodiment of a heat pump according to the invention is shown in a connection to be described with a photovoltaic element 1 as a device for providing thermal and electrical energy.

In the heat pump designed as a refrigerator, a refrigerant is fed as a working medium in the direction of arrow 2 in the circuit. The refrigerant cycle can be divided into three areas: an area in which the refrigerant in the heat pump has a low pressure and a low temperature (eg, 20 ° C) (hereinafter referred to as a low-pressure area), an area in which the refrigerant has a higher Pressure and a higher temperature (eg 60 ° C) (hereinafter referred to as high-pressure area) and an additional area in which the pressure and temperature of the refrigerant between the two aforementioned areas (hereinafter referred to as the medium-pressure region). 4 AT 504 564 B1

The low pressure region is limited in the flow direction of the refrigerant (arrow 2) by a throttle 3 and a first compressor 4, wherein the first compressor 4 (medium pressure compressor) compresses the refrigerant to the pressures and temperatures prevailing in the medium pressure range. The throttle 3 is in the embodiment shown, a controllable electronic expansion valve and controls the flow rate of the refrigerant, which determines the energy conversion of the heat pump. The high pressure area is limited in the flow direction of the refrigerant (arrow 2) by a second compressor 5 and the throttle 3, wherein the second compressor 5 (high pressure compressor) compresses the refrigerant to the pressures and temperatures prevailing in the high pressure region and the throttle 3, the refrigerant to the in the Low pressure range prevailing pressures and temperatures expanded. By lowering the temperature of the refrigerant caused by the throttle 3, the refrigeration for consumer appliances, e.g. Refrigerators, freezers or the like can be provided. Both in the low-pressure and in the high-pressure range heat exchangers are provided, the more detailed determination will be described.

It is essential to the invention that between the first compressor 4 and the second compressor 5, the medium-pressure region is created, in which before the second compressor 5 energy can be introduced in the form of heat, without changing the cooling capacity in the low pressure region, since the first compressor 4 as a pressure barrier acts when thermal energy is introduced into the medium pressure range. In the following, two variants are addressed, how energy is introduced into the medium-pressure region, wherein other possibilities are conceivable within the scope of the invention.

One possibility of energy supply is the heat recovery from the high pressure area to the medium pressure area. This thermal energy recirculation is particularly advantageous when the heat pump is designed as a refrigerating machine, since the heating power is not required in the high-pressure range. For this purpose, a heat exchanger 6 is arranged between the first compressor 4 and the second compressor 5. Starting from a high pressure area, i. in the flow direction of the refrigerant (arrow 2) after the second compressor 5, arranged heat exchanger 7, through which the heating power could otherwise be used for hot or industrial water treatment 16, runs a line 8, which opens into the heat exchanger 6. The (recycled) heat thus fed into the medium-pressure region raises the pressure of the refrigerant upstream of the second compressor 5, as a result of which its torque for compressing the refrigerant to the pressure prevailing in the high-pressure region becomes smaller. The power consumption of the second compressor 5 is reduced by the part of the injected energy, with the result that the coefficient of performance and the energy balance of the heat pump is optimized.

Another way of feeding energy into the medium-pressure region is the heat supply from the photovoltaic element 1. This thermal energy supply can e.g. by means of a medium, which was previously used for cooling the photovoltaic element 1, take place (while also the cooling power generated by the heat pump can be used directly for cooling the photovoltaic element 1). For this purpose, starting from the photovoltaic element 1, a line 9 is provided, which opens into the heat exchanger 6. The temperature range which is fed within the medium-pressure region is designed so that the heat supplied by the photovoltaic element 1 achieves the desired efficiency.

The direct connection of the photovoltaic element 1 to the heat pump is best seen in FIG. 2 and is explained below with reference to an exemplary embodiment which is preferred in practice:

With the photovoltaic element 1 electrical energy is generated, with which two compressors 4, 5 are operated with wholly or partially solar energy. The resulting solar heat is used as described above directly to increase the pressure of the refrigerant in the medium pressure range of the heat pump. The cooling power generated by the heat pump is introduced directly for cooling the photovoltaic element 1. The electrical power of the photovoltaic

Claims (5)

5 AT 504 564 B1 Elements 1 can thus be increased by up to 30%. The saving of electrical energy in this heat pump is up to 50% compared to known from the prior art heat pumps. In summer time, a self-sufficiency of electrical energy of up to 90% for the cooling performance of buildings can be achieved, wherein in the cooling operation by the inventive return of the heating power in the medium-pressure range, the electrical energy consumption is further reduced. The energy of the photovoltaic element 1 is supplied to a DC / DC converter 10 in its direct connection to the heat pump. About the DC / DC converter 10, the photovoltaic element 1 is connected to a frequency converter 11. By means of a device 12 for power measurement and a control system 13, the energy to be supplied by the photovoltaic element 1 is adjusted to the energy demand of the two compressors 4, 5 which is dependent on the heat pump output. The frequency converter 11 operates the two variable frequency compressors 4, 5 for controlling the compressor powers. Within the scope of the invention, as an alternative or in addition to the photovoltaic element 1, it is also possible to provide thermovoltaic elements 15 as a device for providing thermal and / or electrical energy. The thermovoltaic elements 15 are arranged in the embodiment shown in the form of thermal generators in the heat exchanger 7, but can also be arranged in other heat exchangers of the heat pump. The supply of thermal energy in the medium-pressure region via the line 9. The generated electrical energy is supplied analogously to the photovoltaic element 1 via a DC / DC converter 10 to the frequency converter 11 and with the control system 13 and the device 12 for power measurement of the Energy demand of the compressor 4, 5 adjusted. The heat pump can be switched with the valve 14 from the heating mode to the cooling mode. In the context of the invention, a refrigerant is preferably used as the working medium, which exerts as little harmful effect on the environment and in particular on the ozone layer of the earth in case of accidental leakage from the heat pump. Further illustrated in Fig. 2 components of the heat pump according to the invention, such as the connection to a heat reservoir 17, e.g. Ground heat from groundwater, or the connection to a consumer device 18, e.g. a refrigerator, or the connection to the electrical network 19 may be carried out in a manner known per se from the prior art. In summary, an exemplary embodiment can be described as follows: A heat pump leads a working medium in the circuit and has a throttle 3 and two compressors 4, 5. In the flow direction of the working medium (arrow 2), the throttle 3 with the first compressor 4 defines a low-pressure region, the first compressor 4 with the second compressor 5 a medium-pressure region and the second compressor 5 with the throttle 3 a high-pressure region. Starting from at least one device 1,7, 15 for providing thermal energy, a line 8, 9 is arranged for a heat-carrying medium to a heat exchanger 6 in the medium-pressure region. The two compressors 4, 5 are powered directly via a photovoltaic element 1 with power. The resulting solar heat is supplied to a heat exchanger 6 in the medium-pressure region, whereby the pressure of the working medium increases and to the same extent the energy consumption of the second compressor 5 is reduced. Claims 1. A heat pump with two compressors (4, 5) and a throttle (3), which divide a cycle of a heat-carrying working medium into a low, a medium and a high pressure range, and at least one Heat exchanger (6, 7), wherein between the two compressors (4, 5) of the medium-pressure region is limited and wherein in the medium-pressure region, a heat exchanger (6) is arranged, characterized in that starting from at least one device (1, 7, 15) for Providing thermal energy is arranged a line (8, 9) for a heat-carrying medium to the heat exchanger (6) in the medium-pressure region. 2. Heat pump according to claim 1, characterized in that in the flow direction of the working medium (arrow 2) seen first compressor (4) is arranged between the low pressure and medium pressure region and the second compressor (5) between the medium pressure and high pressure range. 3. Heat pump according to claim 1 or 2, characterized in that starting from the high-pressure region in the heat exchanger (6) opening in the medium-pressure region line (8) is arranged. 4. Heat pump according to claim 3, characterized in that the device for providing thermal energy in the high pressure region arranged heat exchanger (7). 5. Heat pump according to one of claims 1 to 4, characterized in that the throttle (3) is an electronically controllable expansion valve. 6. Heat pump according to one of claims 1 to 5, characterized in that at least one device (1, 15) for providing thermal energy is a device (1, 15) for providing thermal and electrical energy. 7. Heat pump according to claim 6, characterized in that the heat pump comprises a frequency converter (11), and that the frequency converter (11) is connected to a device (1, 15) for providing thermal and electrical energy. 8. Heat pump according to claim 7, characterized in that between the frequency converter (11) and the device (1, 15) for providing thermal and electrical energy, a DC / DC converter (10) is arranged. 9. Heat pump according to one of claims 1 to 8, characterized in that the device (1) for providing thermal energy is a photovoltaic element (1). 10. Heat pump according to one of claims 1 to 9, characterized in that the device (15) for providing thermal energy is a thermovoltaic element (15). 11. Heat pump according to one of claims 1 to 10, characterized in that the temperature of the via the line (8, 9) in the heat exchanger (6) fed heat-carrying medium in the medium pressure range between the present in the low pressure region temperature and the present in the high pressure region temperature , 12. A method for operating a heat pump, with which a working medium in a low-pressure region and a high-pressure region is brought to different temperature and pressure levels, wherein by arranging two compressors (4, 5), a medium-pressure region is formed, characterized in that starting from at least a device (1, 7, 15) for providing thermal energy additionally additional heat is fed into the medium-pressure region. 13. The method according to claim 12, characterized in that the additional pressure in the middle area supplied heat by cooling a device (1) for providing thermal energy is obtained. 14. The method according to claim 12 or 13, characterized in that at least one device (1, 15) for providing thermal energy as a device (1, 15) for providing thermal and electrical energy is used and that the compressors (4, 5 ) are operated with the current generated by the device (1, 15) for providing thermal and electrical energy. 15. The method according to any one of claims 12 to 14, characterized in that heat is recycled from the high-pressure region in the medium-pressure region. For this purpose 2 sheets of drawings