Method and improved apparatus for converting thermal energy into kinetic energy

Abstract

The present invention relates to a method for converting thermal energy, in particular energy from the environment, into kinetic energy, and to an apparatus for converting thermal energy into kinetic energy, said apparatus being used to carry out the method. In the method according to the invention, two circuits with fluids are operatively connected to each other in that one fluid influences the other in at least three heat exchangers. The two circuits are further provided with an environmental heat exchanger that pre-sets the temperature of the fluid used. The waste heat used for this purpose can come, for example, from the industrial field.

Description

[Technical field]

[0001] The present invention relates to a method for converting thermal energy, in particular energy from the environment, into kinetic energy, and to a device in which the method can be carried out for converting thermal energy into kinetic energy. [Background technology]

[0002] Providing people with energy is a very important subject. In particular, the generation of "clean" energy is a political goal to protect the environment and slow down or even stop climate change. Known environmentally friendly energy generation facilities include hydroelectric power plants, solar collectors, which are also used industrially in large photovoltaic power plants, and wind turbines, which convert wind power into energy on land, and which are increasingly also used in large marine installations. In the long term, these technologies will be insufficient to stop climate change. In addition, electricity consumption is continuously increasing as a result of electromobility.

[0003] Thus, DE 10 2019 006 184 A1 presents a device for converting thermal energy into kinetic energy by utilizing a heat pump in combination with a thermal power plant. The device is based on two thermodynamic circulation processes. The two circulation processes are connected to each other in the machine by two heat exchangers for the purpose of heat transfer. The device utilizes the ability of the heat pump to absorb thermal energy with a gas in the heat exchanger and achieve high temperatures with a simultaneous increase in gas pressure and a decrease in volume by compression. The amount of energy for operating the pump is much smaller than the amount of energy pumped. The heated fluid is then utilized to evaporate a second fluid so that the gas pressure can be converted into kinetic energy in the heat engine. As in any conventional power plant, the fluid needs to be condensed, so that the unused residual steam is led to a condenser, which is cooled by a very cold fluid from the heat pump circuit, reduced in pressure by an expansion valve. The fluid from the heat engine circuit condenses in the condenser and is pumped back to the heat exchanger for repeated evaporation. The fluid from the heat pump can then be drawn back to the compressor, accompanied by thermal energy from the condenser and the environment, to be heated again in the heat exchanger and also back into the heat exchanger, where the heat is transferred to the fluid from the heat engine circuit. As a result, thermal energy can always be converted into kinetic energy. Since the heat pump can be used to cool and heat alike, the energy conversion machine uses both potentials to make available fluids with boiling points below 273 Kelvin. The condensers used can reach temperatures below 250 Kelvin, so temperature differences of 100 Kelvin or more are possible. A fluid such as isobutane can thus form a high pressure, and after being utilized in the heat engine to convert it into kinetic energy, the gas flows to the condenser at the lowest pressure and at a very low temperature. If, for example, ammonia is used, the condenser can reach a temperature below 250 Kelvin and condense a gas such as isobutane. As a result, the temperature gradient, and therefore the pressure difference in the heat engine, is sufficient to convert most of the energy absorbed in the heat exchanger into kinetic energy.As a specific type of heat engine, the condensing turbine can be made even more efficient by utilizing the enthalpy of vaporization. During the experiments carried out to develop this, the developers realized that the efficiency was still insufficient for effective industrial use.

[0004] It is an object of the present invention to provide an enhanced method and improved apparatus for converting thermal energy into kinetic energy.

[0005] This object is achieved by the features of method claim 1 and apparatus claim 3, the respective dependent claims describing further configurations.

[0006] definition An environment heat exchanger in the context of the present invention is a device in which energy is extracted from the environment in the form of heat, such as waste heat from an industrial process, from a power station for a device, from water or steam, or finally thermal energy directly from the environment, provided that this source of thermal energy is sufficient to provide the levels required within the device.

[0007] When the fluid is heated, it is possible that part of the fluid may simultaneously evaporate, but this need not be described in detail.

[0008] If the fluid is releasing heat, it may also liquefy at the same time, but this need not be discussed in detail. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] DE 10 2019 006 184 A1 Summary of the Invention

[0010] First, some basics for understanding the method and device are described. For heat pumps, the starting point is generally only the efficiency, not the figure of merit. In principle, the pump power consumption, the pump stroke and the pumped water volume are used to calculate the work performed and therefore the efficiency of the pump. In contrast, the water temperature and therefore the pumped heat capacity are not important. In the case of a favorable arrangement, i.e. when the difference between the ambient temperature and the temperature of the pumped medium is large, such a huge amount of heat, a large amount of energy carrier, can be transported with the same pump power. The aim is to make this heat available. So the figure of merit of the heat pump, different from the efficiency, reveals the amount of energy present in the pumped fluid.

[0011] In a conventional cooling system, the figure of merit is 3 to 4 times the energy consumed by its compressor. Thus, with a pump power of 1 kW, a cooling power of up to 4 kW can be expected. The generated cooling is utilized, for example in a refrigerator, to extract heat from food as a thermal energy source, thereby extending the shelf life of the food.

[0012] Since heat pumps follow the first law of thermodynamics, an amount of energy corresponding to the cooling power is removed as heat. The heat released therefore corresponds to the required cooling power and is used to lower the temperature inside the refrigerator to the required level of cooling. The heat released into the surrounding space is dissipated according to the prior art in the refrigerator without further utilization. Thus, for a cooling power of 4 kW per kW of pump power, the amount of heat removed outside the refrigerator is the same 4 kW from the inside plus an additional 1 kW of waste heat from the compressor.

[0013] A heat engine in the form of an ORC steam turbine converts the temperature difference into rotational energy by the expansion of the gases, typically to a high degree in the area of ​​70% or more, the remainder being released to the condenser as heat in a partially condensed fluid. A heat engine requires a hot and a cold side to operate the device. If the cooling body of the heat pump takes the form of a condenser and the hot side of the heat pump takes the form of an evaporator, the elements of the heat pump are arranged such that, when the fluid is suitably selected and heat from the environment is absorbed, the rotational energy is converted to a high degree of electrical energy, with respect to the hot or cold side of the heat engine. The energy of the heat released by the heat engine is large enough to clearly exceed the required pumping energy or energy for the compressor.

[0014] As explained above, power output increases with the magnitude of the temperature difference, so in order to improve the figure of merit, it is desirable to extend the heat pump and heat engine circuits with a suitable number of further heat exchangers.

[0015] Against this background, a method of the invention for converting thermal energy into kinetic energy is presented. In this method, repetitive method steps proceed in parallel in a first circuit and in a second circuit, the circuits being subject to a mutual condition that one condenser of one circuit is the evaporator of the other circuit and vice versa. A fluid in a circuit is always influenced by a fluid in the other circuit, in relation to its temperature, as it moves through the circuit.

[0016] In the first circuit, a first fluid, initially gaseous, is compressed and its temperature increased. The compression creates a pumping motion of the fluid through the circuit. The first fluid is cooled by condensation in the first heat exchanger. The first fluid is further cooled by condensation in the third heat exchanger and reduced in pressure in a pressure reducing valve. It then passes through a second heat exchanger to absorb heat, absorbs more thermal energy in the environment heat exchanger, and is returned to compression.

[0017] The second fluid is pumped through the second circuit and heated in the third heat exchanger, while the first fluid is cooled as described above. It is evaporated in the second environment heat exchanger and further heated in the first heat exchanger. This further heating is accompanied by a first cooling of the first fluid. From the first heat exchanger, the second fluid enters the heat engine, with a resulting pressure drop and thermal energy release. In the heat engine, the resulting rotational energy can be extracted and converted, for example, into electrical energy. After expansion by the heat engine, it is recycled and liquefied in the second heat exchanger, and the sequence begins again with a pumping action in the direction of the third heat exchanger.

[0018] As a result of this method, having two overlapping and mutually influencing circuits, optimal overall conditions of each fluid, especially the second fluid, are achieved, since the second fluid is introduced into the heat engine at its highest temperature and released back into the circuit at its lowest temperature. High kinetic energies can be generated when the temperature difference between the heat engine inlet and the heat engine outlet is particularly large.

[0019] The first fluid, initially gaseous, is compressed to a temperature level where heat is transferred to the second fluid in the first heat exchanger such that the second fluid reaches the desired inlet temperature in the heat engine. The first fluid flows forward in cooled form and is cooled again in the third heat exchanger where heat is transferred to the second fluid. The first fluid then condenses and is expanded by the pressure reducing valve so that it is ready to absorb heat again, first in the second heat exchanger and then in the environment heat exchanger.

[0020] To make such a method optimally viable, it is preferable to use fluids that function effectively under the prevailing climatic conditions and temperature differences resulting from the heat source. Propane, carbon dioxide and ammonia can be mentioned here as examples, but other fluids are not excluded. Among those mentioned, propane has a very good suitability, since it can be very easily controlled and is safer to utilize. Moreover, it does not persist when it enters the environment, since it is not converted to TFA.

[0021] In a particular configuration of the method of the present invention for converting thermal energy into kinetic energy, no further condensation takes place in the third heat exchanger. For the method to proceed optimally, condensation should already be completed in the first heat exchanger. In the optimal case, the first fluid is at the ambient temperature at the outlet of the first heat exchanger. This improves the heat exchange rate of the method.

[0022] In a further configuration of the method for converting thermal energy into kinetic energy according to the invention, the second fluid is already completely evaporated in the second environment heat exchanger. This improvement of the method also leads to an increase in efficiency.

[0023] Furthermore, in certain configurations of the method for converting thermal energy into kinetic energy, measurements of temperature and / or flow rate and / or pressure are performed at at least one point of each circuit. This serves, firstly, to better monitor the method process. Secondly, the periodically sampled data provides information about the process and can warn the user if necessary. For example, these measurements have the purpose of increasing efficiency, but also for safety reasons. Furthermore, this allows control by valves, which allows the energy flow and heat transfer to be optimized, allowing safe choices. For example, too high or too low heat input can be changed before the system overheats or overcools, or before the heat engine is overloaded or underloaded.

[0024] Finally, a further configuration of the method of the invention for converting thermal energy into kinetic energy includes the feature that the waste heat generated in the pump in the second circuit is returned to the circuit of said second circuit between the second environment exchanger and the first heat exchanger or between the first heat exchanger and the heat engine. Thus, even the waste heat formed in the process can be sent for further use, helping to increase efficiency. Similarly, it is also possible to extract heat from other heat-dissipating elements in the circuit and return it to the circuit at a suitable point.

[0025] The improved device for converting thermal energy into kinetic energy for use in the described method includes two circuits for fluids, the first circuit including, in order, a first environmental heat exchanger, a compressor, a first heat exchanger, a pressure reducing valve, and a second heat exchanger. In the first circuit, the first heat exchanger functions as a condenser and the second heat exchanger functions as an evaporator. The second circuit includes, in order, a first heat exchanger, a heat engine, a second heat exchanger, and a pump, and in the second circuit, the first heat exchanger functions as an evaporator and the second heat exchanger functions as a condenser. The two circuits are fluidly unconnected to each other but have a functional relationship in the first and second heat exchangers.

[0026] According to the present invention, a third heat exchanger is arranged downstream of the first heat exchanger in the first circuit, and the third heat exchanger and the second environment heat exchanger are arranged downstream of the pump in the second circuit. The circuit in the third heat exchanger also has a functional relationship between the first circuit and the second circuit. By additionally incorporating the third heat exchanger and the second environment heat exchanger, the heat exchange rate of the device is further increased compared to the devices described in the prior art. The fluid can be even more precisely adjusted to the required temperature and overall conditions in the circuits so that optimal results can be achieved in the heat engine.

[0027] In a particular configuration of the improved device for converting thermal energy into kinetic energy, the device has measuring sensors for temperature and / or flow and / or pressure and a control unit for processing the measurement data. However, in particular to ensure optimal efficiency, it is essential to detect and evaluate the measurement data, such as pressure, temperature, flow, etc., and to carry out the necessary adjustments, such as increasing the pressure in the fluid, changing the supply of heat from the environment, etc. A constant monitoring of the indicators is also required to ensure a constant heat exchange rate in the heat engine.

[0028] According to a particular configuration of the improved device for converting thermal energy into kinetic energy of the present invention, an environmental heat exchanger is integrated into the circuit, which effectively replaces the conventional heat exchanger, whereby thermal energy generated elsewhere is extracted and transferred to the fluid, which broadens the possibilities and helps to adapt the device to the conditions at the site of use.

[0029] In a particular configuration of the improved device for converting thermal energy into kinetic energy, the pump in the second circuit is configured as a compressor. This additional function of the pump has a greater impact on the fluid, since it can be adapted more precisely to the specifications required for the high heat exchange rate of the heat engine.

[0030] Finally, in a particular configuration of the improved device for converting thermal energy into kinetic energy, the first heat exchanger and the third heat exchanger and / or the second environmental heat exchanger are connected in a heat exchange device. Thus, the device can be made much more compact without compromising the heat exchange rate. This allows for use in smaller areas. Furthermore, it is of course also possible to combine other components, separately or together with the mentioned components, into a more compact unit, if possible, for example for reasons of better energy utilization in the system.

[0031] In a final configuration of the improved device for converting thermal energy into kinetic energy, the two circuits are provided with bypass conduits in the region of the environmental heat exchanger. In this way, when the fluid is diverted through the bypass conduits, the system can be protected in a controlled manner from absorbing further energy in the environmental heat exchanger and thus cooled. These bypass conduits also protect against system overheating, so that damage or accidents can be avoided.

[0032] A great advantage of the device is that the first and second environmental heat exchangers can transfer any kind of waste heat to the device, for example from laundry plants, energy generation, waste incineration, landfill degassing and other industrial processes, as well as natural waste heat, for example from high-temperature sources. This does not necessarily have to be done directly, but can also be realized via an upstream heat circuit. This allows a very flexible use in many different locations, preferably in locations where any kind of waste heat is lost without being utilized.

[0033] Many different fluids can be used. Carbon dioxide, ammonia and especially propane are preferred due to their good availability under the conditions prevailing on Earth. These substances are relatively easy to obtain and handle. It is possible to use different fluids in the circuit, provided that they do not affect the heat exchange rate of the device.

[0034] An energy supply shall be provided for all measuring and monitoring equipment as well as for the control equipment. Pumps must also be electrically operated. Furthermore, energy is introduced into the system in an environmental heat exchanger, which can absorb waste heat, for example from industry.

[0035] In the following, the details are summarized in a different logical setting, thereby showing in an altered form the functional relationships of the invention and the resulting results up to energy transformation.

[0036] The method for converting thermal energy into kinetic energy includes repetitive method steps in a first circuit, including absorbing thermal energy from the environment or an external process by evaporation of a first fluid in a first environment heat exchanger, and compressing the gaseous first fluid with an increase in temperature by a compressor, where the compressing creates a pumping motion of the fluid through the first circuit, releasing thermal energy from the first fluid with condensation in the first heat exchanger, and further releasing thermal energy from the first fluid with further condensation in a third heat exchanger, followed by reducing the pressure of the first fluid through a pressure reducing valve and again absorbing thermal energy in a second heat exchanger and evaporating the first fluid.

[0037] At the same time, in the second circuit, there are repetitive method steps, including releasing heat energy with condensation of the second fluid in the second heat exchanger, pumping the second fluid through the second circuit with a pump, absorbing heat energy with evaporation of the second fluid in a third heat exchanger and increasing the vapor pressure in the second circuit. This is followed by absorbing further heat energy from the environment or an external process with further evaporation of the second fluid in a second environment heat exchanger and increasing the vapor pressure in the second circuit, and absorbing further heat energy with further evaporation of the second fluid in the first heat exchanger and increasing the vapor pressure in the second circuit. The second fluid, now in gaseous form, is then led to a heat engine, where the vapor pressure and heat energy are converted into kinetic energy, and at the same time kinetic energy is extracted with a decrease in the vapor pressure and heat energy in the heat engine.

[0038] The two circuits are subject to the mutual condition that one condenser in the first circuit is the evaporator in the other circuit and vice versa. [Brief description of the drawings]

[0039] [Figure 1] FIG. 1 shows a schematic diagram of the device of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0040] The invention will now be illustrated by way of example, in which Figure 1 shows a schematic diagram of an apparatus according to the invention.

[0041] Two circuits 2, 3 are shown, which come into contact at several points. Wherever there is contact of the circuits 2, 3, heat exchangers 6, 8, 11 are located. The fluids moving through the circuits 2, 3 affect each other in the heat exchangers. The compressor 5 is sufficient to achieve a flow movement in the first circuit. The fluid from the first circuit 2 is compressed here and the temperature increases. Thermal energy is released in the first heat exchanger 6, further released in the third heat exchanger 11 and reduced in pressure in the pressure reducing valve 7. The fluid then absorbs thermal energy first in the second heat exchanger 8 and then in the first environmental heat exchanger 4. Thus, the fluid is at its highest temperature after compression and at its lowest temperature after reduction in pressure.

[0042] In the second circuit 3, the fluid is pumped by a pump in the direction of the third heat exchanger 11, where it is heated. The fluid is further heated in the second environment heat exchanger 12, further increased in temperature in the first heat exchanger 6 and then transferred to the heat engine 9. The heat generates kinetic energy, thereby cooling the fluid. The fluid is then liquefied again in the second heat exchanger 8 before being pumped back to the second circuit 3. [Explanation of symbols]

[0043] 1 device 2. First Circuit 3. Second Circuit 4. First environmental heat exchanger 5. Compressor 6 First Heat Exchanger 7 Pressure Reducing Valve 8 Second Heat Exchanger 9. Heat Engines 10. Pump 11 Third heat exchanger 12 Second environmental heat exchanger

Claims

1. A method for converting thermal energy into kinetic energy, comprising: - compressing a first gaseous fluid with an increase in temperature to generate a pumping motion of said fluid through said first circuit (2); cooling said first fluid in a first heat exchanger (6) with condensation; Further cooling the first fluid in a third heat exchanger (11) with further condensation; reducing the pressure of the first fluid in a pressure reducing valve (7); Absorbing heat in a second heat exchanger (8); Further absorbing the thermal energy in a first environmental heat exchanger (4); Iterative method steps Including, In the second circuit (3), pumping a second fluid through said second circuit (3); Heating in a third heat exchanger (11); Evaporating in a second environmental heat exchanger (12); Further heating in a first heat exchanger (6); transferring said second fluid to a heat engine (9) with an associated pressure reduction and thermal energy release; Extracting energy in said heat engine (9); recirculating it to the second heat exchanger (8) and liquefying it; Parallel iterative method steps of wherein said circuits (2, 3) are subject to the mutual condition that the condenser in one circuit is the evaporator in the other circuit, method.

2. 2. Method for converting thermal energy into kinetic energy according to claim 1, characterized in that no further condensation takes place in the third heat exchanger (11).

3. 3. Method for converting thermal energy into kinetic energy according to claim 1 or 2, characterized in that the second fluid is already evaporated in the second environmental heat exchanger (12).

4. 4. A method for converting thermal energy into kinetic energy according to any one of claims 1 to 3, characterized in that at least one point in each circuit (2, 3) is performed with temperature and / or flow and / or pressure measurements, the collected data is evaluated and each circuit is optimized by a closed-loop controller.

5. 5. The method for converting thermal energy into kinetic energy according to any one of claims 1 to 4, characterized in that waste heat generated in a pump (10) in the second circuit (3) is supplied to the second circuit (3) between the second environment heat exchanger (12) and the first heat exchanger (6) or between the first heat exchanger (6) and the heat engine (9).

6. Improved device (1) for converting thermal energy into kinetic energy for the method according to claims 1 to 5, comprising two circuits (2, 3) for a fluid, the first circuit (2) comprising, in turn, a first environment heat exchanger (4), a compressor (5), a first heat exchanger (6), a pressure reducing valve (7) and a second heat exchanger (8), in the first circuit (2) the first heat exchanger (6) functions as a condenser and the second heat exchanger (8) functions as an evaporator, the second circuit (3) comprising, in turn, the first heat exchanger (6), a heat engine (9), the second heat exchanger (8) and a pump (10), in the second circuit (3) the first heat exchanger (6) functions as an evaporator. (6) functions as an evaporator and the second heat exchanger (8) functions as a condenser, the two circuits (2, 3) are fluidly disconnected but have a functional relationship at the first heat exchanger (6) and the second heat exchanger (8), in the first circuit (2) a third heat exchanger (11) is arranged downstream of the first heat exchanger (6), in the second circuit (3) the third heat exchanger (11) and a second environment heat exchanger (12) are arranged downstream of the pump (10), and the circuits (2, 3) have a functional relationship between the first circuit (2) and the second circuit (3) at the third heat exchanger (11).

7. Improved device (1) for converting thermal energy into kinetic energy for the method according to claim 6, characterized in that the device comprises temperature and / or flow rate and / or pressure measuring sensors, a control unit for processing the measurement data and a closed-loop controller for controlling the process.

8. Improved device (1) for converting thermal energy into kinetic energy for the process according to claim 6 or 7, characterized in that the environmental heat exchanger (4, 12) is integrated into an external circuit.

9. 9. The improved device (1) for converting thermal energy into kinetic energy for the process according to claims 6 to 8, characterized in that the pump (10) in the second circuit (3) is configured as a compressor.

10. 10. The improved device (1) for converting thermal energy into kinetic energy for the method according to claims 6 to 9, characterized in that the first heat exchanger (6) and / or the third heat exchanger (11) and / or the second environmental heat exchanger (12) are connected in a heat exchanger device.

11. Improved device (1) for converting thermal energy into kinetic energy for the process according to claims 6 to 10, characterized in that the circuit (2, 3) has a bypass conduit for bypassing the environmental heat exchanger (4, 12).

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