WO2018050408A1

WO2018050408A1 - Waste heat recovery system

Info

Publication number: WO2018050408A1
Application number: PCT/EP2017/071114
Authority: WO
Inventors: Michael Richter; Axel Zuschlag; Gregory Rewers
Original assignee: Robert Bosch Gmbh
Priority date: 2016-09-16
Filing date: 2017-08-22
Publication date: 2018-03-22
Also published as: DE102016217731A1

Abstract

The invention relates to a waste heat recovery system (3) comprising a working fluid circuit (19) which interacts wth a heat exchanger inserted in a coolant circuit (20) of an internal combustion engine (1), the internal combustion engine (1) comprising a cooling system (2) with the coolant circuit (20) and with at least one coolant pump (22), and a coolant radiator (21). The aim of the invention is to provide a waste heat recovery system (3), the coupling of which to the cooling system (2) of the internal combustion engine is improved such that it is optimised in terms of the components thereof. To this end, the heat exchanger is a cooler (35) that is connected to a condenser (31) inserted in the working fluid circuit (19) by means of a working fluid cooling circuit (34) of the waste heat recovery system (3), and the working fluid cooling circuit (34) is connected to the coolant circuit (20). The working fluid cooling circuit (34) and the coolant circuit (20) comprise a common coolant pump (20).

Description

Description Title:

Waste heat recovery system

The invention relates to a waste heat recovery system with a

Arbeitsfluidkreislauf, with a in a coolant circuit of a

Combined internal combustion engine activated heat exchanger, wherein the internal combustion engine has a cooling system with the coolant circuit and with at least one coolant pump, and a coolant radiator.

State of the art

Such a waste heat recovery system is from the

DE 10 2014 019 684 AI known. The waste heat recovery system has a working fluid circuit which cooperates with a heat exchanger connected in a coolant circuit of an internal combustion engine. The internal combustion engine has a cooling system with the coolant circuit and with at least one coolant pump and a coolant radiator. In this case, the heat exchanger is a capacitor which is switched directly into the working fluid circuit.

From DE 10 2013 205 648 AI is another

Waste heat recovery system known. Here, a working fluid circuit of the exhaust heat recovery system into an exhaust pipe of a

Internal combustion engine switched on evaporator, an expansion engine, a condenser and a working fluid pump. The condenser has a coolant supply line and a coolant discharge line, which are connected to a coolant circuit of the internal combustion engine. In this case, a controllable by a bypass valve bypass is arranged between the coolant supply and the Kühlmittelabführleitung. The invention has for its object to provide a waste heat recovery system, the coupling with the cooling system of an internal combustion engine is improved component optimized.

Disclosure of the invention

This object is achieved in that the heat exchanger is a cooler which is connected to a switched-on in the working fluid circuit heat exchanger in the form of a capacitor via a working fluid cooling circuit of the

Waste heat recovery system is connected, and that the

Working fluid cooling circuit is connected to the coolant circuit. These

Design of the waste heat recovery system with the

Working fluid circuit and the working fluid cooling circuit, one in the

Coolant circuit has switched on cooler and a switched-on in the working fluid circuit condenser, and wherein the working fluid circuit and the coolant circuit are interconnected, allows several detailed improvements described in detail below

Waste heat recovery system with respect to its cooling and thus ultimately in terms of the efficiency of the internal combustion engine and the discharged CGremission. In addition, the waste heat recovery system and the entire cooling system can be adapted to a variety of conditions resulting during operation of the internal combustion engine. In development of the invention, the coolant circuit and the

Working fluid cooling circuit on a common coolant pump for the common coolant. This is a significant improvement over systems with a coolant circuit and a working fluid cooling circuit, both of which have independent cooling pumps, because this design, a cooling pump can be saved together with the necessary drive and drive control.

In a further embodiment of the invention, the working fluid cooling circuit and the coolant circuit are connected in parallel with respect to the coolant pump. This is a possible embodiment that follows below possible further embodiments will be described. An alternative embodiment provides that the working fluid cooling circuit and the

Coolant circuit based on the coolant pump are connected in series with each other.

In a further development of the invention, the working fluid cooling circuit is the delivery side of the coolant pump via a connection with the involvement of a in the

Working cooling circuit arranged valve with the coolant circuit and the suction side of the coolant pump via a connection directly to the

Coolant circuit connected. In a further embodiment of the

Working fluid cooling circuit on the delivery side of the coolant pump via a connection to the coolant circuit and the suction side of the coolant pump connected via a connection to the coolant circuit, wherein in the suction-side connection in the working fluid cooling circuit, a 3-way valve is arranged, from which a connection via a connecting line with the conveyor side

Connection is connected and thus represents a bypass to the connections. Again, another or alternative embodiment provides that the working fluid cooling circuit is connected on the delivery side of the coolant pump via a connection and the suction side of the coolant pump via a connection to the coolant circuit, and wherein the downstream

conveyor-side connection in the working fluid cooling circuit a 3-way valve is arranged, of which a connection via a connecting line represents a bypass of the connections.

Finally, it is provided in the serial circuit that the

Working fluid cooling circuit on the output side of the coolant radiator and a

By means of the passes to the coolant radiator with the coolant circuit via a connection and on the suction side of the coolant pump with the coolant

Coolant circuit is connected via a connection, and that between the two connections a valve in the working fluid cooling circuit is arranged.

These are all advantageous embodiments, which can be arbitrarily combined with each other and each other with respect to their individual features, as far as this is technically feasible. Advantage of these described embodiments is:

It eliminates a separate cooling pump for the working fluid cooling circuit; their function is handled by the coolant pump of the coolant circuit.

It eliminates other components in the working fluid cooling circuit, such as a surge tank, connections for filling and venting the working fluid cooling circuit and other components.

There is a defuse of security requirements that

For example, when using an additional electric cooling pump for the working fluid cooling circuit would be required, because if the mechanical coolant pump fails, the vehicle must be stopped.

It is the use of a very high mass flow through the

Coolant circuit possible. The usual electrical separate

Cooling pump for the working fluid cooling circuit is typically limited to a flow rate of two kilograms per second. This may be insufficient at high ambient temperature and high load of the waste heat recovery system so as not to exceed the boiling temperature of the working fluid cooling circuit coolant.

It is the prerequisite for a quick warm up of the

Coolant circuit created via exhaust heat.

The radiator can, in addition to the efficient cooling of the engine and to optimize the overall efficiency of the

Internal combustion engine can be used together with the waste heat recovery system.

In the event that the waste heat recovery system is not active, or if this still reserves in the

Having working fluid cooling circuit, this can also be used for cooling the internal combustion engine. This offers the possibility

Cooling system capacities from the coolant circuit and the Working fluid cooling circuit to use as needed and thus the commissioning of a fan can be delayed or prevented.

In a shutdown of the waste heat recovery system is a virtual increase in the cooling surfaces of the cooling system of

Internal combustion engine possible.

In a further development of the invention, the working fluid cooling circuit has a

Radiator bypass with a radiator bypass control valve to the radiator and / or the working fluid cooling circuit has a condenser bypass with a

Capacitor bypass control valve on. These embodiments are also advantageous in the system described above implemented and expand, for example, the control options or

Control options of the entire system.

Further advantageous embodiments of the invention are the

Drawing description can be seen in the embodiments illustrated in the figures of the invention are described in more detail.

Show it:

1 is a schematic diagram of a waste heat recovery system having a working fluid circuit and a working fluid cooling circuit connected to a coolant circuit of a cooling system of an internal combustion engine in a first embodiment;

FIG. 2 shows a detailed view of a coupling of a working fluid cooling circuit with a coolant circuit in a further embodiment,

FIG. 3 shows a detailed view of a coupling of a working fluid cooling circuit with a coolant circuit in a further embodiment,

FIG. 4 is a schematic diagram of a waste heat recovery system having a working fluid circuit and a working fluid cooling circuit. the with a coolant circuit of a cooling system a

Internal combustion engine is connected in another

embodiment,

FIG. 5 shows a working fluid cooling circuit with a capacitor bypass in a first embodiment,

FIG. 6 shows a working fluid cooling circuit with a condenser bypass in a second embodiment,

7 shows a working fluid cooling circuit with a radiator bypass in a first

Embodiment and

FIG. 8 shows a working fluid cooling circuit with a radiator bypass in one

second embodiment.

Figure 1 shows a waste heat recovery system 3, which at a

Internal combustion engine 1 is installed with a cooling system 2. The

Internal combustion engine 1 further comprises a fresh gas line 4 and a

Exhaust pipe 5 on. About the fresh gas line 4 of the internal combustion engine 1 combustion air is supplied, which is in the embodiment of the compressor 6 of an exhaust gas turbocharger 7, which in turn is driven by a switched-on in the exhaust pipe 5 turbine 8, is compressed. The compressor 6, a charge air cooler 9 and a throttle valve 10 are connected downstream. The individual combustion chambers of the internal combustion engine 1 with simultaneous supply of fuel, such as diesel fuel, supplied fresh gas burns in combustion chambers of the engine lunter generation of work, which is delivered for example via a connected to the transmission of a crankshaft of the engine 1 output shaft 11 to a drive axle 12 with which any vehicle in which the

Internal combustion engine 1 is installed, is driven. About the exhaust pipe 5, the burned in the combustion chambers of the internal combustion engine 1 mixture of fuel and fresh gas as hot exhaust gas is finally discharged into the environment. The exhaust pipe 5 is connected to the fresh gas line 4 via a

Exhaust gas recirculation line 13 with a switched exhaust gas recirculation cooler 14 and an exhaust gas recirculation valve 15 is connected. Via the exhaust gas recirculation line 13 controlled exhaust gas is recycled into the fresh gas line 4 in particular to reduce the harmful exhaust emissions. Downstream of the turbine 8 is an exhaust aftertreatment device 16, which has, for example, a soot filter and / or catalyst turned on. The

Exhaust after-treatment device 16 is also provided to reduce harmful exhaust emissions. Further downstream is in the exhaust pipe 5, a heat exchanger in the form of a superheater 17 of the

Abwärm recovery system 3 is turned on, the one over

Exhaust line bypass 18 controlled bypassed. The superheater 17 is incorporated in a working fluid circuit 19 of the waste heat recovery system 3, as explained in more detail below.

The internal combustion engine 1 further comprises the cooling system 2 with a

Coolant circuit 20 on. The cooling system 2 is used to cool the

Internal combustion engine 1 and has a built-in coolant circuit 20 coolant radiator 21 and a coolant pump 22. The coolant pump 22 conveys the coolant through cooling chambers of the internal combustion engine 1 into the coolant cooler 21, which is connected on the output side to the suction side of the coolant pump 22. The coolant cooler 21 is via one of a

Coolant bypass valve 23 controlled coolant bypass 24 bypass. The passage through the coolant bypass 24 is switched in particular for cold coolant and cold internal combustion engine 1 for quickly reaching the operating temperature of the coolant and the internal combustion engine 1. In the coolant circuit 20, a lubricating oil heat exchanger 25 and a retarder heat exchanger 26 are still involved. By doing

Lubricating oil heat exchanger 25 is cooled by a lubricating oil circuit 27 circulating lubricating oil of the internal combustion engine 1, while in the retarder heat exchanger 26 circulating through a retarder 28

Working hydraulic fluid is cooled. The retarder 28 is for example connected to the output shaft 11 and active in the braking operation of the vehicle. The lubricating oil heat exchanger 25 and the retarder heat exchanger 26 may be turned on as shown in the coolant circuit 20 or in another constellation. Furthermore, the intercooler 9 and the exhaust gas recirculation cooler 14 is suitably incorporated into the coolant circuit 20.

Coming back to the waste heat recovery system 3, this has the working fluid circuit 19 with the superheater 17 switched into the exhaust gas line 5. Furthermore, in the working fluid circuit 19, an expansion machine 29 is turned on, which is driven by the same in the superheater 17 transferred to the gaseous state working fluid under expansion and output power to the internal combustion engine 1 or other machine, such as a generator. In this case, the expansion machine 29 can be bypassed via a controlled working fluid bypass 30. Further, downstream of the expansion machine 29 in the working fluid circuit 19, a condenser 31 is turned on, in which the working fluid is normally cooled back to the liquid state and then a working fluid pump 32 is supplied. The working fluid pump 32 is, for example, electrically driven and promotes the recooled working fluid back to the

Superheater 17. Here, the output side of the working fluid pump 32 a

Pressure equalization tank 33 in the working fluid circuit 19 is turned on.

The aforementioned capacitor 31 is itself part of a

Working fluid cooling circuit 34, which further comprises a cooler 35. The cooler 35 is arranged, for example, in front of or behind the coolant radiator 21 and is cooled by a flow of cooling air, for example from one of the

Internal combustion engine 1 directly or indirectly driven fan 36 flows through.

An essential aspect of the invention is that the

Working fluid cooling circuit 34 is connected to the coolant circuit 20 and the working fluid cooling circuit 34 and the coolant circuit 20 having a common coolant pump 22 for the common coolant. As a result, a separate cooling pump for the working fluid cooling circuit 34 is saved. The various possibilities of interconnecting the coolant circuit 20 and the working fluid cooling circuit 34 will be explained in detail in the following. For controlling the internal combustion engine 1 and the previously described

Components and optionally also other components such as the fuel injection system, an electronic control device 37 is present, the entire system, for example, according to specifications of a vehicle driver and state variables of the overall system, such as temperature readings

T and pressure readings p, which are taken anywhere, controls.

In the embodiment shown in FIG. 1, the working fluid cooling circuit 34 is connected to the coolant circuit 20 on the suction side of the coolant pump 22 on the output side of the condenser 34 via a connection 48a.

On the delivery side of the coolant pump 22, the working fluid cooling circuit 34 is also connected to the coolant circuit 20 via a connection 48b, wherein the conveyor side of the coolant pump 22 and the connection 48b in a supply line 49 to the radiator 35, a valve 38 is switched into the working fluid cooling circuit 34. In the connection 48b, the common coolant of the working fluid cooling circuit 34 and the coolant circuit 20 is at a comparable temperature level. When the valve 38 is opened, a defined amount of coolant is conveyed from the coolant pump 22 into the coolant circuit 20 and the working fluid cooling circuit 34. Increasing closure of the valve 38 reduces the amount of coolant circulating through the working fluid cooling circuit 34 to a full stop. In the embodiment shown in Figure 1 and described above are the

Coolant circuit 20 and the working fluid circuit 34 with respect to the common coolant pump 22 connected in parallel.

The reproduced in Figure 2 in a detailed representation connection of the

Arbeitsfluidkühlkreislaufs 34 to the coolant circuit 20 differs from that of Figure 1 in that here although the working fluid cooling circuit 34 on the delivery side of the coolant pump 22 also via the connection 48 a with the

Coolant circuit 20 is connected, but here in the supply line 49 to the radiator 35, no valve 38 is present. Instead, a 3-way valve 39 designed as a thermostat is arranged in the working fluid cooling circuit 34 before the suction-side connection 48a, its preferably third connection via a connecting line 40 to the supply line 49 to the radiator 35th is connected downstream of the conveyor-side connection 48a. In the

Connecting line 40 is an opening in the direction of the radiator 35

Check valve 41 installed. Thus, a defined volumetric flow of coolant from the working fluid cooling circuit 34 into the coolant circuit 20 can be conducted via the 3-way valve 39 designed as a thermostat, while the connecting line 40 with the check valve 42 forms a bypass to the connections 48a, 48b. Thus, that is, the working fluid cooling circuit 34 can, with a corresponding position of the 3-way valve 39 of the

Coolant circuit 20 are shut off and it flows in the result no

Coolant through the working fluid cooling circuit 34th

In the embodiment according to FIG. 3, the working fluid cooling circuit 34 is again connected to the coolant circuit 20 via connections 48a, 48b, as described above, and the 3-way valve 39 is arranged here in the supply line 49 in front of the cooler 35.

Again, preferably the third port of the 3-way valve 39 via the connecting line 40 via the connection 48 a with the suction side of

Coolant pump 22 connected. Depending on the position of the 3-way valve 39 is coolant through the radiator 35 (according to arrow 1) or through the

Connecting line 40 (arrow 2) promoted back to the suction side of the coolant pump 22. In this case, the volume flow of the coolant removed via the connection 48b is almost the same for all positions of the 3-way valve 39. In order to prevent that coolant is conveyed on the wrong way back to the condenser 31, here is the output side of the capacitor 31 in the line leading to the connecting line 40 or connection 48 a

Working fluid cooling circuit 34, the check valve 41 is arranged. The 3-way valve 39 may be a complex valve in the embodiments of Figures 2 and 3 or consist of several valves. While in the embodiments of Figures 1 to 3 of

Working fluid cooling circuit 34 and the coolant circuit 20 with respect to the coolant pump 22 are connected in parallel to each other, they are connected in series in the embodiment of Figure 4 to each other. Here, the coolant pump 22 conveys coolant through the internal combustion engine 1 and then through the coolant cooler 21 or the coolant bypass 24. Subsequently, a the connection 48b to the working fluid cooling circuit 34 in front of the cooler 35 via a connection line 42. By the downstream of the junction of the connection line 42 arranged in the working fluid cooling circuit 34 valve 38, the mass flow or volume flow of the coolant is adjusted by the working fluid cooling circuit 34. In order to ensure that the coolant conveyed by the coolant pump 22 also flows through the cooler 35 and then through the condenser 31, in particular when the valve 38 is fully open, the connection 48a is downstream of a suction connection line 43 which connects the working fluid cooling circuit 34 to the coolant pump 22 on the suction side , a check valve 41 is arranged. Otherwise, the illustrated corresponds

System to the system shown in Figure 1.

The detailed views shown in Figures 5 and 6 show basically already previously described embodiments of the working fluid cooling circuit 34, wherein in both figures, the working fluid cooling circuit 34 one of a

Capacitor bypass control valve 45 controlled capacitor bypass 44 to the capacitor 31 has. In this case, the condenser bypass control valve 45 can be controlled both actively via, for example, the control device 37 or passively in the form of a thermostat. The condenser bypass control valve 45 may be installed in the working fluid cooling circuit 34 both downstream and upstream of the condenser 31. Basically, any combination of valve types (passive or active) and any mounting position

(downstream, upstream) possible. The benefit of this

Capacitor bypass 44 is also independent of a parallel or serial circuit of the working fluid cooling circuit 34 and the coolant circuit 20 with respect to the coolant pump 22.

Advantages of the condenser bypass 44 are: - There is a decoupling of the volume flow in the cooler 35 and in the condenser 31, whereby a more flexible and simultaneously

needs-based cooling capacity displacement and cooling of the

Working fluid cooling circuit 34 is possible. Thus, a simpler needs-based cooling surface enlargement of the coolant radiator 21 is possible. This brings with it the advantage that, by displacing cooling demand from the coolant circuit 20 into the working fluid cooling circuit 34, commissioning of the fan 36 can be avoided or delayed. Thus, it is possible, for example, to completely use all the cooling capacities for the vehicle cooling, ie for the coolant circuit 20, by completely bypassing the capacitor 31.

Free cooling capacities in the working fluid cooling circuit 34 can be used for the coolant circuit 20 without the volume flow in the condenser 31 or possible pressure losses rising. This has the advantage that despite qualification of the working fluid cooling circuit 34 for the coolant circuit 20 no separate interpretation of

Capacitor 31 is necessary for example for higher volume flows.

FIGS. 7 and 8 show different embodiments of the invention

Working fluid cooling circuit 34 with a radiator bypass 46 controlled by a radiator bypass control valve 47 to the radiator 35. Through the radiator bypass 46, a portion of the circulating through the working fluid cooling circuit 34 volume flow of the coolant, which may be, for example cooling water, is passed to the radiator 35. This is at low

Temperatures of advantage, otherwise very low pressures in the

Working fluid cooling circuit 34 arise. These pressures in turn mean high demands on the components and the capacity. In addition, at low pressures in the working fluid cooling circuit 34, heat in the condenser 31 is very difficult to remove. A countermeasure would be to greatly reduce the mass flow in the working fluid cooling circuit 34 or the additional cooling pump. However, such a measure is not sufficient at very low coolant temperatures in the working fluid cooling circuit 34, which is why "bypassing" of the cooler 35 via the cooler bypass 46 is advantageous Training as a thermostat to be controlled

Radiator bypass control valve 47 may be incorporated into the working fluid cooling circuit 34 both downstream and upstream of radiator 35. each Combination of types of the cooler bypass control valve 47 (passive or active) and each installation location (downstream, upstream of the radiator 35) is possible.

Advantages of this embodiment are:

By the cooler bypass 46, a further degree of freedom arises in the regulation of the coolant temperature in the working fluid cooling circuit 34.

The coolant volume flow and the coolant temperature can be controlled independently of each other by, for example, the rotational speed of an optional separate cooling pump for the working fluid cooling circuit 34 or the Zumischgrad when combined with the coolant circuit 20th

The heating phase of the working fluid cooling circuit 34 can be shortened.

The system becomes more independent of lower ambient temperatures and prevention of the occurrence of negative pressure is possible as well as the sensitivity to the filling amount of the working fluid cooling circuit 34 is lower.

In the case of a coupled working fluid cooling circuit 34 and

Coolant circuit 20 is the prerequisite for a faster

Warming the coolant of the coolant circuit 20 via exhaust heat possible.

Finally, it is pointed out that any individual features described above can be combined with each other and with each other.

Claims

claims

A waste heat recovery system (3) comprising a working fluid circuit (19) cooperating with a heat exchanger connected in a coolant circuit (20) of an internal combustion engine (1), wherein the

Internal combustion engine (1) a cooling system (2) with the coolant circuit (20) and with at least one coolant pump (22) and a

Having coolant cooler (21),

characterized in that the heat exchanger is a cooler (35) which is switched on with one in the working fluid circuit (19)

Condenser (31) via a working fluid cooling circuit (34) of the

Waste heat recovery system (3) is connected, and that the working fluid cooling circuit (34) is connected to the coolant circuit (20).

2. waste heat recovery system (3) according to claim 1,

characterized in that the coolant circuit (20) and the working fluid cooling circuit (34) have a common coolant pump (22).

3. waste heat recovery system (3) according to claim 2,

characterized in that the working fluid cooling circuit (34) and the coolant circuit (20) with respect to the coolant pump (22) are connected in parallel. A waste heat recovery system (3) according to claim 3,

characterized in that the working fluid cooling circuit (34) on the delivery side of the coolant pump (22) via a connection (48b) using a arranged in the working cooling circuit (34) valve (38) with the coolant circuit (20) and the suction side of the coolant pump (22) via a Connection (48a) directly with the

Coolant circuit (20) is connected.

A waste heat recovery system (3) according to claim 3,

characterized in that the working fluid cooling circuit (34) on the delivery side of the coolant pump (22) via a connection (48b) to the coolant circuit (20) and the suction side of the coolant pump (22) via a connection (48a) with the coolant circuit (20) is connected, and in front of the suction-side connection (48a) in the

Working fluid cooling circuit (34) a 3-way valve (39) is arranged, of which a connection via a connecting line (40) is a bypass of the connections (48b, 48a).

A waste heat recovery system (3) according to claim 3,

characterized in that the working fluid cooling circuit (34) on the delivery side of the coolant pump (22) via a connection (48b) and the suction side of the coolant pump (22) via a connection (48a) to the coolant circuit (20) is connected, and that downstream of the conveyor-side connection ( 48b) in the working fluid cooling circuit (34) a 3-way valve (39) is arranged, of which a connection via a connecting line (40) is a bypass of the connections (48b, 48a).

A waste heat recovery system (3) according to claim 2,

characterized in that the working fluid cooling circuit (34) and the coolant circuit (20) with respect to the coolant pump (22) are connected in series with each other. A waste heat recovery system (3) according to claim 7,

characterized in that the working fluid cooling circuit (34) on the output side of the coolant radiator (21) and a Kühlmittelby passes (24) to the coolant radiator (21) with the coolant circuit (20) via a connection (48b) and the suction side of the coolant pump (22) with the coolant circuit (20) is connected via a connection (48a), and that between the two connections (48b, 48a) a valve (38) in the working fluid cooling circuit (34) is arranged.

The waste heat recovery system (3) of any one of claims 2 to 8, characterized in that the working fluid cooling circuit (34) includes a radiator bypass (46) having a radiator bypass control valve (47) to the radiator (35).

A waste heat recovery system (3) according to any one of claims 2 to 9, characterized in that the working fluid cooling circuit (34) has a condenser bypass (44) with a condenser bypass control valve (45) to the condenser (31).