EP3159506B1 - Functional synergies in the integration of orc systems in combustion engines - Google Patents

Description

Field of invention

The invention relates to a drive system which comprises an internal combustion engine and a cooling device for dissipating waste heat from the internal combustion engine, the cooling device comprising: a cooler for transferring heat to an ambient medium, in particular wherein the cooler is an air cooler and the ambient medium is air; and a thermodynamic cyclic process device, in particular an ORC device, with a working medium, an evaporator for evaporating the working medium by transferring waste heat from the internal combustion engine to the working medium, an expansion device for generating mechanical energy and a condenser for condensing the working medium expanded in the expansion device. The invention also relates to a corresponding method for dissipating waste heat from an internal combustion engine with a cooling device.

State of the art

An economical solution for increasing the efficiency of internal combustion engines with great potential, especially in trucks, is to use waste heat from the internal combustion engine with a thermal cycle (e.g. with an organic Rankine cycle system, ORC system). Some of the requirements or given conditions here are low additional costs, less space available, little intervention and influence on the further system. It is therefore sensible or necessary to use synergies with existing components.

If a force-generating process, such as the Organic Rankine Cycle (ORC), is operated in the vicinity of an internal combustion engine, both the direct integration of the generated energy and mechanical power into the system (e.g. can the expansion machine of the ORC system to support the combustion engine), as well as their provision for ancillary units is often advantageous, as conversion losses occur when converting mechanical energy into electrical energy. In addition, the savings in motors for drive or generators for output also save costs and the compactness can be increased, which are both critical factors for the integration of a force-generating process in the aforementioned environment. In addition, the expansion machine can also drive a generator, whereby the electrical energy generated thereby can be used to drive one or more components in the vicinity of the internal combustion engine. Hybridization should also be mentioned in this context, i.e. the direct or indirect use of the electrical energy generated in the drive train of the internal combustion engine. For example, one or more electric motors supplied with the generated electrical energy can be provided in a truck for driving one or more drive shafts.

The document US 2015/276284 A1 discloses a cooling device for a condenser of a system for a thermodynamic cycle in an arrangement with an internal combustion engine.

The document US 2013/312418 A1 discloses a system for converting thermal energy to mechanical energy in a vehicle.

Description of the invention

The object of the invention is to provide synergies in the use of waste heat from internal combustion engines.

The object is achieved by a drive system according to claim 1.

The drive system according to the invention comprises an internal combustion engine and a cooling device for dissipating waste heat from the internal combustion engine, the cooling device comprising: a cooler for transferring heat to an ambient medium, in particular wherein the cooler is an air cooler and the ambient medium is air; and a thermodynamic cycle device, in particular an ORC device, with a working medium, an evaporator for evaporating the working medium by transferring waste heat from the internal combustion engine to the working medium, an expansion device for generating mechanical energy and a condenser for condensing the working medium expanded in the expansion device; wherein the cooling device furthermore comprises a condenser cooling fluid circuit for removing heat from the condenser of the thermodynamic cycle device via the cooler. This embodiment of the drive system according to the invention enables the engine cooler to be used for heat dissipation from the condenser of the thermodynamic cycle device, in particular for heat dissipation from the ORC condenser. The cooling fluid can in particular be or comprise water, preferably with a proportion of antifreeze.

The cooling device further comprises an internal combustion engine cooling fluid circuit, a first branch of the internal combustion engine cooling fluid circuit leading through the evaporator for transferring heat to the working medium. In this way, the heat in the engine's cooling circuit can be introduced into the thermodynamic cycle.

The internal combustion engine cooling fluid circuit comprises in the flow direction of a cooling fluid upstream of the evaporator a first branch into a second branch of the internal combustion engine cooling fluid circuit to bypass the evaporator and a merging of the second branch with the first branch after the evaporator, the second branch having a first valve, preferably a controlled valve. In this embodiment, the outlet temperature of the engine cooling fluid (in particular engine cooling water) is set via the valve to a higher value than in normal operation according to the prior art. The increase in temperature results in a higher performance of the thermodynamic cycle.

A further development is that the internal combustion engine cooling fluid circuit comprises a second branch in the flow direction of the cooling fluid upstream of the evaporator into a third branch of the internal combustion engine cooling fluid circuit, and the third branch is designed to supply cooling fluid through the radiator and back into the first branch lead, the second branch preferably comprising a second valve, in particular a three-way valve. In this way, an emergency running capability of the drive system is provided. Such emergency running capability can occur if the temperature of the internal combustion engine is too high due to failure of the thermodynamic cycle or due to insufficient heat absorption by the thermodynamic cycle. If the heat transfer capacity of the cooler is insufficient and / or if no or insufficient cooling of the engine cooling fluid takes place in the evaporator, then engine cooling fluid can be fed directly to the cooler via the second valve. This increases the temperature of the engine cooling fluid supplied to the radiator, the logarithmic temperature difference increases and more heat is transferred.

According to another development, the internal combustion engine cooling fluid circuit can comprise a third branch in the flow direction of the cooling fluid downstream of the evaporator into a fourth branch of the internal combustion engine cooling fluid circuit, the fourth branch being designed to guide cooling fluid through the radiator and back into the first branch. wherein the third branch preferably comprises a third valve, in particular a three-way valve, wherein in combination with the previous development a merging of the fourth branch into the third branch is provided. These advantages of this development are analogous to those of the previous development, it is only branched off after the evaporator, so that a more moderate heat extraction is possible than before the evaporator. When combining the two developments, both valves can also be opened at the same time.

Another development is that the internal combustion engine cooling fluid circuit comprises a merging of the third or fourth branch with the condenser cooling fluid circuit upstream of the radiator in the direction of flow of the cooling fluid. In this way, a simple interconnection of the internal combustion engine cooling fluid circuit with the condenser cooling fluid circuit is provided. However, it is disadvantageous that the condenser of the thermodynamic cycle device is also flowed through with relatively hot engine cooling fluid, which has a negative effect on the performance of the expansion device.

According to another development, the cooler can have an input collector, an output collector, and ducts lying therebetween, each of which has opposite regions of the input collector and the output collector connect with each other, wherein an input of the condenser cooling fluid circuit in the input collector and an input of the third and fourth branch of the internal combustion engine cooling fluid circuit in the input collector are spaced apart, in particular are arranged at respective end regions of the input collector, and an output of the condenser cooling fluid circuit from the output collector and an output of the third or fourth branch of the internal combustion engine cooling fluid circuit from the output collector are spaced apart from one another, in particular are arranged at respective end regions of the output collector, the input and output of the condenser cooling fluid circuit and the internal combustion engine cooling fluid circuit in opposite regions of the input collector or the output collector are arranged.

In this way, a division of the existing cooler surface into a high temperature area (cooling fluid of the internal combustion engine) and a low temperature area (cooling fluid for the condenser of the thermodynamic cycle device) is made possible. As a result, the condenser can be provided with the lowest possible temperature and the excess heat of the cooling fluid of the internal combustion engine can be dissipated at a high temperature level, which has a positive effect on the dissipation of heat to the environment via the cooler. The division of the mass flows into partial mass flows to the connections of the input collector and thus also through the cooler surface is preferably carried out via the second and / or third valve. The adaptation of the proportions of the hot or cold cooler surface takes place automatically in this connection depending on the partial mass flows.

Another development is that the cooling device further comprises at least one heat exchanger for transferring heat in the exhaust gas of the internal combustion engine to the internal combustion engine cooling fluid circuit. This means that the heat in the exhaust gas from the internal combustion engine can be used. In addition, the sound-absorbing property of an exhaust gas heat exchanger can be used to reduce the size of the actual silencer or to replace it completely. Other heat sources that can be used are the charge air and / or the oil of the internal combustion engine.

According to another development, the drive system furthermore comprises a generator with which mechanical energy generated by the expansion device can be converted into electrical energy. The generated electrical energy can be used to operate electrical components in the drive system or it can be fed into an electrical power grid.

Another development is that mechanical energy generated by the expansion device can be used via a respective electrical, mechanical or hydraulic coupling to (a) drive a fan of the condenser and / or a fan of the cooler; and / or (b) driving a circulation pump in the internal combustion engine cooling fluid circuit and / or a feed pump of the thermodynamic cycle device and / or a circulation pump in the condenser cooling fluid circuit and / or a water pump and / or a hydraulic pump and / or an oil pump; and / or (c) driving an alternator and / or a starter of the drive system; and / or (d) driving a refrigeration compressor of an air conditioning system; and or (e) coupling the mechanical energy generated by the expansion device into a drive train of the internal combustion engine, in particular directly onto a drive shaft. In this way, further synergies are made available in the drive system.

According to another development, a partial flow of the evaporated working medium can be used by means of a further expansion machine to drive a fan of the condenser and / or a fan of the cooler. This minimizes conversion losses.

Another development consists in the fact that heat can be extracted from the condensed working medium and / or from the internal combustion engine cooling fluid circuit for feeding into a heating device. Thus, for example, a passenger compartment or a driver's cab can be heated. Another advantage is that when exhaust heat is used, the engine is heated up faster from standstill and thus runs faster in an efficient and low-emission operating point.

The object on which the invention is based is further achieved by a method according to the invention according to claim 11.

The method according to the invention is suitable for dissipating waste heat from an internal combustion engine with a cooling device, wherein the cooling device comprises a cooler, a thermodynamic cycle device, in particular an ORC device, with a working medium, an evaporator, an expansion device and a condenser, and a condenser cooling fluid circuit, and wherein the method comprises the following steps: transferring heat to an ambient medium with the cooler, wherein in particular the cooler is an air cooler and the ambient medium is air; Evaporation of the working medium with the evaporator by transferring waste heat from the internal combustion engine to the working medium; Generating mechanical energy with the expansion device; and condensing the working medium expanded in the expansion device with the condenser; and the method is characterized by removing heat from the condenser of the thermodynamic cycle device via the cooler.

Unless otherwise stated, the advantages of the method according to the invention and its developments correspond to those of the device according to the invention.

According to the method according to the invention, the following further steps are carried out: leading a first branch of an internal combustion engine cooling fluid circuit through the evaporator for transferring heat to the working medium; and first branching off of a cooling fluid in the internal combustion engine cooling fluid circuit in the flow direction upstream of the evaporator into a second branch of the internal combustion engine cooling fluid circuit to bypass the evaporator and merging the second branch with the first branch after the evaporator.

In a further development, the following further steps are carried out: second branching off of the cooling fluid in the flow direction upstream of the evaporator into a third branch of the internal combustion engine cooling fluid circuit, the third branch leading cooling fluid through the radiator and back into the first branch; and / or third branching of the cooling fluid in the flow direction after the evaporator into a fourth branch of the internal combustion engine cooling fluid circuit, the fourth branch leading cooling fluid through the radiator and back into the first branch; wherein the cooler has an input header, an output header, and channels lying therebetween, which respectively connect opposite regions of the input header and the output header to one another, and wherein an input of the condenser cooling fluid circuit into the input header and an input of the third and fourth branches of the internal combustion engine, respectively -Cooling fluid circuit in the input header are spaced from each other, in particular are arranged at respective end regions of the input header, and wherein an outlet of the condenser cooling fluid circuit from the output header and an output of the third or fourth branch of the internal combustion engine cooling fluid circuit from the output header are spaced apart, in particular are arranged at the respective end areas of the output header, the inlet and outlet of the condenser cooling fluid circuit and the internal combustion engine cooling fluid circuit at opposite areas of the input header or of the output collector are arranged.

The invention also provides a cooling device and a corresponding method for operating the cooling device.

The cooling device according to the invention comprises: a first cooling fluid circuit, a second cooling fluid circuit and a cooler with an input collector, an output collector, and ducts lying therebetween which connect opposite regions of the input collector and the output collector with one another, an input of the first cooling fluid circuit into the input collector and an inlet of the second cooling fluid circuit into the inlet collector are spaced apart from one another, in particular are arranged at respective end regions of the inlet collector, and wherein an outlet of the first cooling fluid circuit from the outlet collector and an outlet of the second cooling fluid circuit from the outlet collector are spaced apart from one another, in particular at respective end regions of the outlet collector are arranged, the input and output of the first cooling fluid circuit and the second cooling fluid circuit at each opposite areas of the input collector and the output collector are arranged. A controllable valve is preferably provided in the first cooling fluid circuit and / or a controllable valve is provided in the second cooling fluid circuit. The cooler can transfer heat from the first and second cooling fluid circuits, preferably to a cooling medium, wherein the cooling medium can comprise, for example, water or air.

The method according to the invention for operating the cooling device according to the invention comprises performing the following steps: feeding a first cooling fluid in the first cooling fluid circuit into the inlet of the first cooling fluid circuit in the inlet header of the cooler; Feeding a second cooling fluid in the second cooling fluid circuit into the inlet of the second cooling fluid circuit in the inlet header of the cooler; Leading the first cooling fluid from the outlet of the first cooling fluid circuit from the cooler; and guiding the second cooling fluid from the outlet of the first cooling fluid circuit from the cooler. In particular, the first and second cooling fluids have the same composition.

In this way, the existing cooler surface can be divided into a high temperature area (cooling fluid of the first cooling fluid circuit) and a low temperature area (cooling fluid of the second cooling fluid circuit). The division of the mass flows into partial mass flows to the connections of the input collector (i.e. the respective inlets of the first and second cooling fluid circuit) and thus also the division of the (partial) mass flows through the cooler surface is preferably carried out via one or more valves in the first and / or second Cooling fluid circuit. The adaptation of the proportions of the hot or cold cooler surface takes place automatically depending on the partial mass flows.

The developments mentioned can be used individually or, as claimed, can be combined with one another in a suitable manner.

Further features and exemplary embodiments as well as advantages of the present invention are explained in more detail below with reference to the drawings. It should be understood that the embodiments do not fall within the scope of the present Exhaust invention. It is further understood that some or all of the features described below can also be combined with one another in other ways.

drawings

Fig. 1

shows a first embodiment of the drive system according to the invention.

Fig. 2

shows a second embodiment of the drive system according to the invention.

Fig. 3

shows a third embodiment of the drive system according to the invention.

Fig. 4

shows a fourth embodiment of the drive system according to the invention.

Fig. 5

illustrates the variability of the cooler surfaces.

Fig. 6

is an exemplary representation of the cooling of mixed cooling water in a T-Q diagram.

Fig. 7

is an exemplary representation of the cooling of separate cooling water in a T-Q diagram.

Fig. 8

illustrates various further synergies in the drive system according to the invention.

Embodiments

One possibility, when using waste heat from an internal combustion engine by means of a thermodynamic cyclic process device - such as an ORC system - to exploit synergies with existing components of internal combustion engines, is to use the engine cooler for heat dissipation from the ORC condenser. In operating states with moderate load, such as driving straight ahead and moderate outside temperatures, the entire heat of the engine can be conducted through the ORC system and released into the environment in the cooler become. Operation with a moderate load accounts for the majority of the time in most trucks.

The ORC system is designed in such a way that it can absorb all of the heat from the internal combustion engine in nominal operation (driving straight ahead, outside temperature equal to the nominal temperature / the design temperature). Conversely, however, this means that it cannot absorb all of the heat in the maximum load points (uphill, high outside temperatures). Since the heat extracted from the ORC is of a lower temperature than the engine cooling water, the heat dissipation deteriorates due to the decreasing temperature difference to the environment ΔT _log : $$\dot{Q}=\mathit{UA}\cdot \mathrm{\Delta }{T}_{\mathit{log}}$$

wobei die Temperaturdifferenzen der Medien (Kühlfluid und Luft) vor dem Wärmeaustausch (ΔT₁) und nach dem Wärmeaustausch (ΔT₂) gebildet werden.The logarithmic temperature difference is defined as $$\mathrm{\Delta }{T}_{\mathit{log}}=\frac{\mathrm{\Delta }{T}_1-\mathrm{\Delta }{T}_2}{\ln \left(\mathrm{\Delta }{T}_1/\mathrm{\Delta }{T}_2\right)}$$

whereby the temperature differences of the media (cooling fluid and air) are formed before the heat exchange (ΔT ₁ ) and after the heat exchange (ΔT ₂ ).

If the logarithmic temperature difference decreases, the required area increases with the same amount of heat, which, however, can usually not be implemented in the vehicle for reasons of installation space. The problem is exacerbated when other heat sources are included, e.g. Heat from an exhaust gas recirculation cooler (EGR cooler) or the heat from an ORC system that uses exhaust gas heat.

For a simple and fast implementation of the integration of an ORC in a vehicle, it is important to minimize the structural intervention and to limit the influence on the engine and at the same time to ensure a high efficiency of the ORC process.

Regarding the advantages of using waste heat from the cooling water of the internal combustion engine with an ORC device and using the with the ORC system The energy gained in the drive device includes the large increase in efficiency of the motor in the range of several percent, cost savings and space savings through fewer components compared to ORC systems that use exhaust gas heat. In the first embodiment of the invention, it is disadvantageous that the cooler generally cannot guarantee the heat dissipation of the ORC when the engine is at maximum load, which, however, is remedied or at least mitigated in the further embodiments.

In the embodiments described below, water is used as the cooling fluid (cooling water) only by way of example. Furthermore, the cooler is only provided as an air cooler by way of example, with waste heat being transferred to air. According to the invention, however, another medium (such as water, for example) can also absorb the heat dissipated in the cooler.

Fig. 1 shows a first embodiment of the drive system according to the invention.

In this embodiment, the drive system 100 according to the invention comprises an internal combustion engine 10 and a cooling device for dissipating waste heat from the internal combustion engine, the cooling device comprising: an air cooler 20 for transferring heat to air; and an ORC device 30 with a working medium, an evaporator 31 for evaporating the working medium by transferring waste heat from the internal combustion engine 10 to the working medium, an expansion device 32 for generating mechanical energy (which is converted into electrical energy here, for example via a generator G) and a condenser 33 for condensing the working medium expanded in the expansion device 32; wherein the cooling device further comprises a condenser cooling fluid circuit 40 for removing heat from the condenser 33 of the thermodynamic cycle device via the cooler 20. The cooling device further comprises an internal combustion engine cooling fluid circuit 50, a first branch 51 of the internal combustion engine cooling fluid circuit 50 leading through the evaporator 31 for transferring heat to the working medium. The internal combustion engine cooling fluid circuit has a first branch 81 into a second branch 52 of the upstream of the evaporator in the direction of flow of the cooling water Combustion engine cooling fluid circuit 50 for bypassing the evaporator 31 and a junction 91 of the second branch 52 with the first branch 51 after the evaporator 31, the second branch 52 having a controlled valve 71, for example with a thermostat.

This is a basic interconnection and enables the use of energy from the engine cooling water. In one example, the outlet temperature of the engine cooling water (MKW) is increased to approximately 110 ° C. via the controlled valve (in particular thermostatic valve) 71. By default, the MKW outlet temperature is lower, in the range of 80 ° C. The increase results in a higher performance of the ORC process. In an alternative embodiment, instead of the generator G, the energy can also be coupled in directly (mechanically or hydraulically), as is the case with all of the following interconnections.

The following problem arises during operation: The system 100 has no emergency running capability in the event of an ORC failure or insufficient heat dissipation. If the ORC process 30 is at the limit of its heat absorption or is not in operation, the water circuit 50 heats up and the engine 10 overheats or is regulated down by an engine controller.

Fig. 2 shows a second embodiment of the drive system according to the invention. The same reference symbols denote the same components as in FIG Fig. 1 . Only the additional components are described below.

Compared to the first embodiment, in the second embodiment of the drive system 200, a coupling of heat from the exhaust gas of the engine 10 via an exhaust gas heat exchanger 15 into the internal combustion engine cooling fluid circuit 50 is provided. The internal combustion engine cooling fluid circuit 50 contains a second branch 82 in the flow direction of the cooling fluid upstream of the evaporator 31 into a third branch 53 of the internal combustion engine cooling fluid circuit 50, the third branch 53 being designed to carry cooling fluid through the radiator 20 and back into the first branch 51 to lead, the second branch 82 a second valve 72, for example a three-way valve 72 comprises. If the heat transfer capacity of the cooler 20 is not sufficient, water can be fed directly to the second valve 72 Cooler 20 are performed. The internal combustion engine cooling fluid circuit 50 has a third branch 83 in the flow direction of the cooling fluid downstream of the evaporator 31 into a fourth branch 54 of the internal combustion engine cooling fluid circuit 50, the fourth branch 54 leading cooling water through the radiator 20 and back into the first branch 51, whereby the third branch 83 has a third valve 73, in particular a three-way valve 73, a junction 94 of the fourth branch 54 in the third branch 53 being provided. The internal combustion engine cooling fluid circuit 50 comprises a junction 95 of the third and fourth branches 53, 54 with the condenser cooling fluid circuit 40 upstream of the radiator 20 in the direction of flow of the cooling fluid.

Emergency operation is possible via the 3-way valves 72 and 73. When the ORC is operating, the mean temperature at the inlet of the cooler 20 falls (due to the merging 95 of the internal combustion engine cooling fluid circuit 50 and the condenser cooling fluid circuit 40), which has a negative effect on the heat transfer capacity, which is determined by the logarithmic temperature difference between the heat absorbing and the heat dissipating Medium is determined. If the heat transfer capacity of the radiator 20 is insufficient and / or if there is no or insufficient cooling of the engine cooling water in the evaporator 31, then engine cooling water is fed directly to the radiator 20 via one of the two valves 72 or 73 or by actuating both valves. This increases the temperature of the water supplied to the cooler 20, the logarithmic temperature difference increases and more heat is transferred. However, it is disadvantageous that the ORC also has relatively hot water flowing through it, which has a negative effect on the electrical power.

Fig. 3 shows a third embodiment of the drive system according to the invention. The same reference symbols denote the same components as in FIG Fig. 1 and 2 . Only the additional components are described below.

According to the third embodiment of the drive system 300 according to the invention, the cooler 20 has an input collector 21, an output collector 25, and has channels lying in between, which connect opposite areas of the input collector 21 and the output collector 25 with one another, with an input 22 of the condenser cooling fluid circuit 40 in the input collector 21 and an input 23 of the third branch 53 of the internal combustion engine cooling fluid circuit 50 in the input collector 21 are arranged at respective end regions of the input collector 21, and wherein an output 26 of the condenser cooling fluid circuit 40 from the output collector 25 and an output 27 of the third branch 53 of the internal combustion engine cooling fluid circuit 50 from the output collector 25 are arranged at respective end regions of the output collector 25, wherein the inlet 22, 23 and outlet 26, 27 of the condenser cooling fluid circuit 40 as well as of the internal combustion engine cooling fluid circuit 50 are arranged in opposite areas of the input collector 21 and the output collector 25, respectively.

The existing radiator area is thus divided into a high temperature area (engine cooling water, MKW) and a low temperature area (return to the ORC condenser). Depending on the operating point, part of the MKW mass flow can be passed through the ORC 30 and part can be cooled directly against air, as was described for the second embodiment. This makes it possible to separate the two mass flows, and in this way the lowest possible temperature can be made available to the ORC condenser and the excess heat can be removed at a high temperature level, which has a positive effect on the performance of a cooler and also has a positive effect on the auxiliary energy requirement for dissipating the heat to the environment.

The third embodiment provides a solution for realizing a division of the two partial flows over the surface of the cooler in the simplest possible way and for setting this division advantageously depending on the operating state. The requirements here are that most of the heat is conducted through the ORC in order to achieve the greatest possible increase in the efficiency of the overall system. Furthermore, it is particularly advantageous to use the lowest temperature for cooling the capacitor in order to ensure a higher efficiency of the ORC process. In addition, suitable return temperatures for the motor must be maintained. Although this could be achieved by structurally or hydraulically separate coolers, they are, however then the areas available for the respective mass flows are fixed, which does not, however, match different load points.

The mass flow in the branch 82 or 83 is divided by means of the valve 72 or 73. Depending on the temperature or another characteristic value, this leads a partial flow of the MKW to the cooler 20. The temperature limit depends on whether the variant with valve 72 or 73 is present. For example, when a maximum cooling water temperature is reached, the valve 72 would switch the flow in the direction of the cooler 20 and bypass the ORC. If the required cooling is not achieved, the valve 73 directs the cooling water in the direction of the cooler 20.

Fig. 4 shows a fourth embodiment of the drive system according to the invention. The same reference symbols denote the same components as in FIG Figs. 1 to 3 . Only the additional components are described below.

According to the fourth embodiment 400 of the drive system according to the invention, a further branch is provided in front of the radiator 20 compared to the third embodiment 300 in order to guide hot cooling fluid via a heat sink 110 in order to use some of the heat for other purposes, for example for heating purposes.

The mode of operation of the division of the mass flows in the third and fourth embodiment is described below in connection with Fig. 5 described. The adaptation of the proportions of the hot or cold cooler surface takes place automatically in this connection depending on the mass flows which are passed through the 3-way valve 72 or 73 to the cooler. The greater the mass flow ṁ _{H of} the hot MKW or ṁ _{K of} the cold condenser circuit, the greater the respective proportion of the cooler surface. The underlying operating principle is that the pressure difference between the flow and return is the same. If a first mass or volume flow into the cooler is increased at a first connection, this would result in a greater pressure loss in the first step in the cooler channels through which this first volume flow flows. However, since the channels are connected via the collector, there is the same pressure loss across all channels, so that the volume flow through the channels through which the second mass flow flows increases. However, if the second mass flow remains constant, then the number of channels must be reduced so that more area is available for the larger first mass flow and the pressure losses are adjusted accordingly.

By separating temperature levels, the available heat transfer surface of the cooler 20 is advantageously used in the best possible way. Compared to the (previously described) mixing of the temperatures of two partial flows, significantly lower temperatures can be achieved on the cold side. This has advantages when operating an ORC but also for all other applications where two temperature levels are to be cooled back via a circuit, as is e.g. is the case with stationary engines for cooling the engine cooling water and the charge air. The proposed interconnection allows heat to be dissipated to the environment with the greatest possible temperature difference, which leads to a reduction in the auxiliary energy requirement, and the lower temperature volume flow is cooled to lower temperatures than if the two volume flows are mixed. As shown, the device can also be provided in a cooler by connecting any number of coolers by means of pipelines.

The Figures 6 and 7 explain the functionality and advantages of the interconnection according to the third and fourth embodiment in comparison to the second embodiment in TQ diagrams (T: temperature; Q: heat flow).

Fig. 6 shows an example of the cooling of the water mass flow from 90 ° C, whereby the hotter of the two heat sources enables a temperature of 115 ° C. A re-cooling temperature of the water of 70 ° C is reached.

When using two temperature levels, as in Fig. 7 illustrated, the first mass flow enters the cooler at 115 ° C. and is cooled down to 88 ° C. in this example, this temperature being set when 20% of the total mass flow flowing through the cooler is at a high temperature level. As described above, the areas are divided according to the mass flow, and thus 20% of the area is available for the heat transfer of the first, hot mass flow. If you now calculate the heat flows, however, 27% of the total amount of heat is transferred over this area. The remaining 73% the amount of heat is then transferred over the remaining 80% of the surface, which is now the case at lower temperatures. This amount of heat can be transferred with a flow temperature of the hot water of 84 ° C and a return temperature of 65 ° C, which means a return temperature of 5 K lower. This goes hand in hand with an increase in the performance of the ORC or an improvement in heat transfer in other components (intercooler, etc.).

It should be noted here that the temperature and power values described are only to be seen as examples; further potential can be raised by optimizing and adapting temperature limits. In addition to the temperature, an optimization also takes into account the influence of the mass flow on the heat transfer capacity / performance of a heat exchanger.

The drive system can be further developed with regard to further synergies that are associated with Fig. 8 and each of which can be used individually or in combination. The mechanical energy generated by the expansion device can be used via a respective electrical, mechanical or hydraulic coupling for (a) driving a fan of the condenser 30 and / or a fan of the cooler; and / or (b) driving a circulation pump 101 in the internal combustion engine cooling fluid circuit and / or a feed pump 102 of the thermodynamic cycle device and / or a circulation pump 103 in the condenser cooling fluid circuit and / or a water pump and / or a hydraulic pump and / or an oil pump; and / or (c) driving an alternator 105 and / or a starter of the drive system; and / or (d) driving a refrigeration compressor 106 of an air conditioning system. A partial flow of the evaporated working medium can be used to drive a fan of the condenser and / or a fan 107 of the cooler. This minimizes conversion losses. Furthermore, heat can be extracted from the condensed working medium and / or from the internal combustion engine cooling fluid circuit for feeding into a heating device.

The illustrated embodiments are exemplary only, and the full scope of the present invention is defined by the claims.

Claims (12)

1. Drive system, comprising:

   a combustion engine (10); and

   a cooling device for discharging heat from the combustion engine;

   wherein the cooling device comprises:

   a radiator (20) for transferring heat to a surrounding medium, wherein in particular the radiator is an air cooler and the surrounding medium is air; and

   a thermodynamic cycle device (30), in particular an ORC device, having a working medium, an evaporator (31) for evaporating the working medium by transferring waste heat of the combustion engine (10) to the working medium, an expansion device (32) for generating mechanical energy, and a condenser (33) for condensing the working medium expanded in the expansion device (32);

   wherein the cooling device comprises a condenser coolant circuit (40) for discharging heat from the condenser (33) of the thermodynamic cycle device (30) via the radiator (20); and

   wherein the cooling device further comprises a combustion engine coolant circuit (50), wherein a first branch (51) of the combustion engine coolant circuit passes through the evaporator (31) for transferring heat to the working fluid;

   characterized in that

   the combustion engine coolant circuit in the flow direction of a cooling fluid upstream of the evaporator comprises a first branch-off (81) into a second branch (52) of the combustion engine coolant circuit (50) for bypassing the evaporator (31) and a merging (91) of the second branch (52) with the first branch (51) downstream of the evaporator (31), the second branch (52) comprising a first valve (71), preferably a controlled valve.
2. Drive system according to claim 1, wherein the combustion engine coolant circuit (50) in the flow direction of the cooling fluid upstream of the evaporator (31) comprises a second branch-off (82) into a third branch (53) of the combustion engine coolant circuit (50), and wherein the third branch (53) is configured to move cooling fluid through the radiator (20) and back into the first branch (51), wherein the second branch-off (82) preferably comprises a second valve (72), in particular a three-way valve.
3. Drive system according to any one of claims 1 to 2, wherein the combustion engine coolant circuit (50) comprises, in the flow direction of the cooling fluid downstream of the evaporator (31), a third branch-off (83) into a fourth branch (54) of the combustion engine coolant circuit (50), and wherein the fourth branch (54) is configured to move cooling fluid through the radiator (20) and back into the first branch (51), wherein the third branch-off (83) preferably comprises a third valve (73), in particular a three-way valve, wherein in combination with claim 4, a merging (94) of the fourth branch (54) into the third branch (53) is provided.
4. Drive system of claim 2 or 3, wherein the combustion engine coolant circuit (50) in the flow direction of the cooling fluid upstream the radiator comprises a merging (95) of the third (53) and/or fourth branch (54) with the condenser coolant circuit (50).
5. Drive system of claim 2 or 3, wherein the radiator (20) has an inlet collector (21), an outlet collector (25), and intermediate channels interconnecting respective opposite portions of the inlet collector (21) and the outlet collector (25), and wherein an inlet (22) of the condenser cooling fluid circuit (40) into the inlet collector (21) and an inlet (23) of the third (53) and/or fourth branch (54) of the combustion engine coolant circuit (50) into the inlet collector (21) are spaced from each other, in particular arranged at respective end portions of the inlet collector, and wherein an outlet (26) of the condenser coolant circuit (40) from the outlet collector (25) and an outlet (27) of the third (53) and/or fourth branch (54) of the combustion engine coolant circuit (50) from the outlet collector (25) are spaced from each other, in particular arranged at respective end portions of the outlet collector, wherein the inlet (22, 23) and outlet (26, 27) of the condenser coolant circuit (40) and the combustion engine coolant circuit (50) are each arranged at respective opposite areas of the inlet collector (21) and the outlet collector (25).
6. Drive system according to any one of claims 1 to 5, wherein the cooling device further comprises at least one heat exchanger (15) for transferring heat in exhaust gas of the combustion engine to the combustion engine coolant circuit.
7. Drive system according to any one of claims 1 to 6, further comprising a generator (G), by means of which the mechanical energy generated by the expansion device (32) is convertible into electrical energy.
8. Drive system according to any one of claims 1 to 7, wherein mechanical energy generated by the expansion device (32) can be used via a respective electrical, mechanical or hydraulic coupling for

   (a) driving a fan of the condenser (30) and / or a fan of the radiator; and / or

   (b) driving a circulation pump (101) in the combustion engine coolant circuit and / or a feed pump (102) of the thermodynamic cycle device and / or a circulation pump (103) in the condenser coolant circuit and / or a water pump and / or a hydraulic pump and / or an oil pump; and or

   (c) driving a generator (105) and / or a starter of the drive system; and / or

   (d) driving a refrigeration compressor (106) of an air conditioner; and / or

   (e) coupling the mechanical energy generated by the expansion device in a drive train of the combustion engine, in particular directly to a drive shaft.
9. Drive system according to any one of claims 1 to 8, wherein a partial flow of the vaporized working medium is usable to drive a fan of the condenser and / or a fan (107) of the radiator and / or a refrigeration compressor.
10. Drive system according to any one of claims 1 to 9, wherein heat from condensed working medium and / or from the combustion engine coolant circuit can be coupled out for feeding into a heating device.
11. Method for discharging heat from a combustion engine by means of a cooling device, wherein the cooling device comprises a radiator, a thermodynamic cycle device, in particular an ORC device, with a working medium, an evaporator, an expansion device and a condenser and a condenser coolant circuit, and wherein the method comprises the following steps:

    transferring heat to a surrounding medium with the radiator, wherein in particular the radiator is an air cooler and the surrounding medium is air;

    vaporizing the working medium with the evaporator by transferring heat from the combustion engine to the working medium;

    generating mechanical energy by means of the expansion device;

    condensing the working medium expanded in the expansion device by means of the condenser;

    discharging heat from the condenser of the thermodynamic cycle device via the radiator; and

    passing a first branch of a combustion engine coolant circuit through the evaporator to transfer heat to the working fluid;

    characterized by

    first branching-off of a cooling fluid in the combustion engine coolant circuit in the flow direction upstream the evaporator into a second branch of the combustion engine coolant circuit for bypassing the evaporator and merging the second branch with the first branch downstream the evaporator.
12. Method of claim 11, further comprising the steps of:

    second branching-off of the cooling fluid upstream of the evaporator into a third branch of the combustion engine coolant circuit, the third branch passing cooling fluid through the radiator and back into the first branch; and / or

    third branching-off of the cooling fluid downstream of the evaporator into a fourth branch of the combustion engine coolant circuit, the fourth branch passing cooling fluid through the radiator and back into the first branch;

    wherein the radiator has an inlet collector, an outlet collector, and intermediate channels interconnecting respective opposite portions of the inlet collector and the outlet collector, and wherein an inlet of the condenser cooling fluid cycle into the inlet collector and an inlet of the third and/or fourth branches of the combustion engine coolant circuit into the inlet collector are spaced from each other, in particular are arranged at respective end portions of the inlet collector, and wherein an outlet of the condenser coolant circuit from the outlet collector and an outlet of the third and/or fourth branch of the combustion engine coolant circuit from the outlet collector, respectively, are spaced from each other, in particular arranged at respective end portions of the outlet collector, wherein the inlet and outlet of the condenser coolant circuit and of the combustion engine coolant circuit are arranged at respective opposite portions of the inlet and the outlet collector.

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