WO2017002624A1

WO2017002624A1 - Power generation system

Info

Publication number: WO2017002624A1
Application number: PCT/JP2016/067819
Authority: WO
Inventors: 晋福永
Original assignee: いすゞ自動車株式会社
Priority date: 2015-06-30
Filing date: 2016-06-15
Publication date: 2017-01-05
Also published as: JP2017014949A

Abstract

Provided is a power generation system comprising: an engine (10) which discharges exhaust and through which circulating cooling water passes; a Rankine cycle in which disposed sequentially within a circulation flow path (41) are an evaporator (43) that uses cooling water to evaporate a working fluid having a boiling point lower than that of the cooling water, an expander (44) that expands the working fluid, a condenser (45) that condenses the working fluid, and a pump (42) that causes the working fluid to circulate within the circulation flow path (41); a cooling water passage (30) that introduces the cooling water that has passed through the engine (10) to the evaporator (43); a first bypass passage (31a) that branches from the cooling water passage (30) and then connects thereto; and a heat exchanger (24) that is provided at a location where an exhaust passage (20) for the exhaust and the first bypass passage (31a) intersect, and that recovers the heat from the exhaust to the cooling water in the first bypass passage (31a).

Description

Power generation system

The present disclosure relates to a power generation system, and more particularly, to a power generation system having a Rankine cycle in which an evaporator evaporates a working fluid with engine coolant.

In recent years, in order to regenerate power using waste heat generated in a vehicle, mounting of a power generation device having a Rankine cycle on the vehicle has been studied. The Rankine cycle is an evaporator that evaporates the working fluid with a heat source, an expander that expands the working fluid, a condenser that condenses the working fluid with a cooling source, and circulates the working fluid in the circulation channel. Arranged in order of circulatory organs.

An organic Rankine cycle that uses a medium with a low boiling point as a working fluid is used as the Rankine cycle. For example, Patent Document 1 below discloses a Rankine cycle in which an evaporator heats a working fluid with engine coolant.

Japanese Unexamined Patent Publication No. 2005-282363

The temperature of the cooling water that has passed through the engine is not always the same temperature, but varies depending on the operating conditions of the vehicle. For this reason, when the temperature of the cooling water is low (for example, when the engine is warmed up), the evaporator cannot properly evaporate the working fluid with the cooling water, and the Rankine cycle may not operate.

Therefore, the present disclosure has been made in view of these points, and an object thereof is to appropriately evaporate a working fluid with engine cooling water in a Rankine cycle.

In one aspect of the present disclosure, an exhaust gas is discharged and an evaporator through which circulating cooling water passes, and an evaporator that evaporates a working fluid having a lower melting point than the cooling water by the cooling water in the circulation flow path. , An expander that expands the working fluid, a condenser that condenses the working fluid, a Rankine cycle that is arranged in order of the circulator that circulates the working fluid in the circulation flow path, and the cooling water that has passed through the engine A first cooling water passage that is introduced into the evaporator, a second cooling water passage that is branched from the first cooling water passage and is connected to the first cooling water passage, an exhaust passage for the exhaust, and the second Provided is a power generation system comprising: a heat exchanger provided at a location where the cooling water passage intersects, and recovering the heat of the exhaust gas into the cooling water of the second cooling water passage.
According to such a power generation system, when the cooling water that has passed through the engine passes through the heat exchanger in the second cooling water passage, the heat of the exhaust gas is recovered, so that the temperature of the cooling water rises. And since the cooling water whose temperature rose is introduced into the evaporator, even if the temperature of the cooling water immediately after passing through the engine is low, the evaporator can appropriately heat the working fluid using the cooling water as a heat source. As a result, the Rankine cycle can be started early.

The power generation system is provided at a branch point of the first cooling water passage with the second cooling water passage, and adjusts a flow rate of the cooling water flowing from the first cooling water passage to the second cooling water passage. A first flow rate adjusting member may be further provided.

The power generation system further includes a control unit that controls the operation of the first flow rate adjusting member, and the control unit controls the first flow rate adjusting member according to an evaporation state of the working fluid in the evaporator. It is good also as operating and adjusting the flow volume of the cooling water which flows into the said 2nd cooling water channel | path.

In addition, the power generation system adjusts a bypass passage that bypasses the evaporator in the first cooling water passage, a flow rate of cooling water introduced into the evaporator, and a flow rate of cooling water flowing into the bypass passage. And a flow rate adjusting member.

The power generation system further includes a control unit that controls the operation of the second flow rate adjustment member, and the control unit operates the second flow rate adjustment member when the engine is warmed up, so that the evaporator The cooling water may be caused to flow through the bypass passage without introducing the cooling water into the bypass passage.

According to the present disclosure, there is an effect that the working fluid can be appropriately evaporated by the engine coolant in the Rankine cycle.

FIG. 1 is a schematic diagram illustrating an example of a configuration of a power generation system S according to an embodiment of the present disclosure. FIG. 2 is a schematic diagram illustrating a configuration of a power generation system 900 according to a comparative example.

<Configuration of power generation system>
The configuration of the power generation system S according to one embodiment of the present disclosure will be described with reference to FIG. Drawing 1 is a mimetic diagram showing an example of composition of power generation system S concerning one embodiment.

The power generation system S is mounted on a vehicle having an engine that is an internal combustion engine. For example, the power generation system S is mounted on a large vehicle such as a truck or a bus. The power generation system S regenerates power by using the waste heat generated in the vehicle by the Rankine cycle. As shown in FIG. 1, the power generation system S includes an engine 10, an exhaust passage 20, a cooling water passage 30, a Rankine cycle 40, a sensor group 70, and an ECU 80.

The engine 10 is an engine including a plurality of cylinders, and is a diesel engine in the present embodiment. The engine 10 generates power by burning and expanding a mixture of fuel and intake air (air) in a cylinder. The intake air is drawn into the cylinders of the engine 10 through an intake passage (not shown). Further, the engine 10 exhausts exhaust gas (exhaust gas) after combustion.

The exhaust passage 20 is a passage for exhausting the exhaust discharged from the engine 10 to the outside of the vehicle. In FIG. 1, the exhaust flow path is indicated by a dashed arrow. In the exhaust passage 20, a supercharger 22, an aftertreatment device 23, and a heat exchanger 24 are provided.

The supercharger 22 is a device that supercharges intake air sucked into the engine 10 by using exhaust pressure as a power source. The supercharger 22 is, for example, a turbocharger, and includes a turbine provided in the exhaust passage 20 and a compressor provided in the intake passage.

The post-processing device 23 is a device that purifies exhaust gas. For example, the post-processing device 23 collects PM in exhaust gas or selectively reduces and purifies NO _x in exhaust gas using ammonia (NH ₃ ) hydrolyzed from urea water as a reducing agent. To do.

The heat exchanger 24 is provided at a location where the exhaust passage 20 and the cooling water passage 30 (specifically, a first bypass passage 31a described later) intersect. The heat exchanger 24 is a device that recovers the heat of the exhaust gas in the exhaust passage 20 into the cooling water in the cooling water passage 30. Thereby, the cooling water flowing through the cooling water passage 30 is warmed.

The cooling water passage 30 is a passage for circulating cooling water for cooling the engine 10 in order to prevent the engine 10 from being overheated. In FIG. 1, the flow path of the cooling water is indicated by solid arrows. The cooling water passage 30 is provided so that the cooling water passes through the engine 10, and the cooling water takes the heat of the engine 10 to lower the temperature of the engine 10. In the present embodiment, the cooling water warmed after passing through the engine 10 is introduced into the evaporator 43 of the Rankine cycle 40 as a heat source. The cooling water passage 30 includes a first bypass passage 31a, a second bypass passage 31b, a third bypass passage 31c, a radiator 32, a pump 33, a first adjustment valve 34, a second adjustment valve 35, A third adjustment valve 36 is provided.

The first bypass passage 31 a is a passage that branches from the downstream side of the engine 10 in the cooling water passage 30 and is connected to the cooling water passage 30 on the upstream side of the evaporator 43. The first bypass passage 31a is configured to pass through the heat exchanger 24 on the way. Thereby, the cooling water flowing through the first bypass passage 31a recovers the heat of the exhaust gas by the heat exchanger 24 and is warmed. The cooling water sent from the first bypass passage 31a to the cooling water passage 30 joins with the cooling water that does not flow through the first bypass passage 31a, whereby the temperature of the cooling water sent to the evaporator 43 rises. In the present embodiment, the cooling water passage 30 corresponds to the first cooling water passage, and the first bypass passage 31a corresponds to the second cooling water passage.

The second bypass passage 31b is a passage that branches from the upstream of the evaporator 43 of the Rankine cycle 40 in the cooling water passage 30 and bypasses the evaporator 43. For example, when the engine 10 is warmed up, the cooling water is bypassed from the evaporator 43 by the second bypass passage 31b.

The third bypass passage 31 c is a passage that branches from the upstream side of the radiator 32 in the cooling water passage 30 and bypasses the radiator 32. For example, when the engine 10 is warmed up, the engine 10 is warmed by the cooling water flowing through the third bypass passage 31c.

The radiator 32 dissipates the cooling water whose temperature has increased by passing through the engine 10. Specifically, the radiator 32 lowers the temperature of the cooling water by releasing the heat of the sent cooling water into the atmosphere. A cooling fan may be provided behind the radiator 32 in order to promote heat dissipation of the cooling water.

The pump 33 circulates the cooling water in the cooling water passage 30. The pump 33 is provided on the downstream side of the engine 10 and pumps the cooling water. The pump 33 operates by receiving a driving force from the engine 10, for example.

The first adjusting valve 34 is a flow rate adjusting member that adjusts the flow rate of the coolant that has passed through the engine 10 to the first bypass passage 31a. The first adjustment valve 34 is provided at a branch point between the cooling water passage 30 and the first bypass passage 31a. Thereby, the flow rate of the cooling water for recovering the heat of the exhaust in the heat exchanger 24 can be adjusted.

The second adjustment valve 35 adjusts the flow rate of the cooling water to be sent to the evaporator 43 and the flow rate of the cooling water to be diverted to the second bypass passage 31b. The second adjustment valve 35 is provided at the branch point of the cooling water passage 30 to the second bypass passage 31b. In the present embodiment, the first adjustment valve 34 corresponds to a first flow rate adjustment member, and the second adjustment valve 35 corresponds to a second flow rate adjustment member.

The third adjustment valve 36 adjusts the flow rate of the cooling water to be sent to the radiator 32 and the flow rate of the cooling water to be diverted to the third bypass passage 31c. The third adjustment valve 36 is provided at the branch point of the cooling water passage 30 to the third bypass passage 31c.

Rankine cycle 40 is a power generation cycle that generates electric power using cooling water that has passed through engine 10. As shown in FIG. 1, the Rankine cycle 40 includes a circulation channel 41, a pump 42, an evaporator 43, an expander 44, and a condenser 45. In the Rankine cycle 40, a pump 42, an evaporator 43, an expander 44, and a condenser 45 are arranged in this order in the circulation flow path 41 to form a closed circuit.

The circulation channel 41 is a channel through which the working fluid circulates, and is indicated by a one-dot chain line in FIG. The Rankine cycle 40 of the present embodiment is an organic Rankine cycle in which chlorofluorocarbon, which is a medium having a low boiling point, is circulated as a working fluid. The melting point of the working fluid is lower than the melting point of the cooling water. As the working fluid, for example, known HFC-245fa and HFC-134a are used.

The pump 42 is a circulator that circulates the working fluid in the circulation channel 41. The pump 42 sucks the liquid-phase working fluid and pumps it to the evaporator 43. As the pump 42, a centrifugal pump, a gear pump, or the like is used.

The evaporator 43 is provided on the downstream side of the pump 42 in the circulation flow path 41 and evaporates the working fluid with cooling water. Specifically, the evaporator 43 heats the working fluid by exchanging heat between the working fluid sent from the pump 42 and the cooling water flowing through the cooling water passage 30. In the present embodiment, the cooling water whose exhaust heat has been recovered by the heat exchanger 24 is introduced into the evaporator 43, so that the working fluid can be heated by the cooling water whose temperature is higher than when passing through the engine 10.

The expander 44 is provided on the downstream side of the evaporator 43 in the circulation channel 41, and expands the gas phase working fluid heated by the evaporator 43. The expander 44 generates a rotational driving force by expanding the working fluid. A power generator 44 a is connected to the expander 44. The generator 44a generates electric power by being rotated by the rotational driving force generated by the expander 44. The generated electric power is supplied to, for example, a vehicle battery.

The condenser 45 is provided on the downstream side of the expander 44 in the circulation channel 41, and condenses the working fluid expanded by the expander 44. Specifically, the condenser 45 liquefies the working fluid by exchanging heat between the working fluid discharged from the expander 44 and the atmosphere as a cooling source. The liquefied working fluid is supplied to the pump 42.

The sensor group 70 has a plurality of sensors and can detect various states relating to the vehicle. For example, the sensor group 70 detects the temperature of the cooling water in the cooling water passage 30. The sensor group 70 may detect the heating state of the working fluid in the evaporator 43.

The ECU 80 is an electronic control unit (Electric Control Unit) including a microcomputer having a CPU, a ROM, a RAM, and the like. The ECU 80 controls the operation of each device described above. For example, the ECU 80 has a function of a control unit that controls operations of the first adjustment valve 34, the second adjustment valve 35, and the third adjustment valve 36. Further, the ECU 80 may control the operation of the Rankine cycle 40.

<About the flow of cooling water during Rankine cycle operation>
In the power generation system S described above, the flow of cooling water during the operation of the Rankine cycle 40 will be described. Here, it is assumed that the exhaust gas is discharged from the engine 10 and the cooling water is circulating in the cooling water passage 30.

First, the first adjustment valve 34 adjusts the opening and closing of the valve so that a part of the cooling water passing through the engine 10 flows to the first bypass passage 31a. Then, the cooling water that has flowed into the first bypass passage 31 a recovers the heat of the exhaust gas that flows through the exhaust passage 20 by the heat exchanger 24. The cooling water from which the heat has been recovered merges with the cooling water that has not flowed through the first bypass passage 31a at the connection point between the first bypass passage 31a and the cooling water passage 30. Thereby, the cooling water is warmed and becomes higher than the temperature when passing through the engine 10.

The cooling water whose temperature has been increased is introduced into the evaporator 43 of the Rankine cycle 40. Thereby, since heating of the working fluid by the cooling water as a heat source is promoted, the Rankine cycle 40 can operate appropriately. In particular, even when the temperature of the cooling water that has passed through the engine 10 is low, the temperature is increased by the heat exchanger 24, so that the evaporator 43 can appropriately heat the working fluid. As a result, the Rankine cycle 40 can be started early.

The cooling water that has passed through the evaporator 43 is radiated when passing through the radiator 32, or bypasses the radiator 32 through the third bypass passage 31c. When the coolant passes through the engine 10, it absorbs heat inside the engine 10 and warms up. Thereafter, the cooling water circulates as described above, and continues to serve as a heat source for heating the working fluid in the evaporator 43.

Note that the ECU 80 may control the open / close state of the first adjustment valve 34 in accordance with the heating state of the working fluid in the evaporator 43. For example, when the working fluid is sufficiently heated in the evaporator 43, the ECU 80 changes the open / close state of the first adjustment valve 34 so that the cooling water does not flow into the first bypass passage 31a. Thereby, since cooling water does not collect | recover the heat | fever of exhaust_gas | exhaustion in the heat exchanger 24, it can suppress that cooling water warms up excessively. As a result, it is not necessary to cool the excessively heated cooling water with the radiator 32.

In addition, even when the cooling water recovers the heat of the exhaust gas in the heat exchanger 24 when the engine 10 starts to warm up, the temperature of the cooling water does not immediately rise to a temperature at which the working fluid can be appropriately heated in the evaporator 43. There is. Therefore, the ECU 80 may control the second adjustment valve 35 so that the cooling water flows to the second bypass passage 31b without being introduced into the evaporator 43 at the start of warm-up. In such a case, the cooling water that has not been heat-recovered as the working fluid in the evaporator 43 passes through the engine 10, so that the temperature of the engine 10 having a low temperature can be effectively increased. Can be promoted.

<Effect in this embodiment>
The effectiveness of the power generation system S according to the present embodiment will be described in comparison with the power generation system 900 according to the comparative example illustrated in FIG.

FIG. 2 is a schematic diagram showing a configuration of a power generation system 900 according to a comparative example. In the comparative example, the heat exchanger 24, the first bypass passage 31a, and the first adjustment valve 34 shown in FIG. 1 are not provided. That is, in the comparative example, the cooling water that has passed through the engine 10 is introduced into the evaporator 43 of the Rankine cycle 40 without collecting the heat of the exhaust. In such a comparative example, when the temperature of the cooling water that has passed through the engine 10 is low, the evaporator 43 cannot appropriately heat the working fluid using the cooling water as a heat source, and the Rankine cycle 40 may not operate. In particular, when the engine 10 is warm when the temperature of the engine 10 is low, the temperature of the cooling water passing through the engine 10 is also low, so the evaporator 43 cannot properly heat the working fluid with the cooling water.

In contrast, in the present embodiment, the cooling water that has passed through the engine 10 includes the heat exchanger 24 and the first bypass passage 31a so that the heat of the exhaust can be recovered. In such a case, when the cooling water that has passed through the engine 10 passes through the heat exchanger 24 in the first bypass passage 31a, the temperature of the cooling water rises in order to recover the heat of the exhaust gas. For this reason, even if the temperature of the cooling water immediately after passing through the engine 10 is low, the cooling water whose temperature has risen is introduced into the evaporator 43, so that the evaporator 43 appropriately heats the working fluid using the cooling water as a heat source. it can. As a result, it becomes possible to start the Rankine cycle 40 early.

As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

This application is based on a Japanese patent application (Japanese Patent Application No. 2015-130701) filed on June 30, 2015, the contents of which are incorporated herein by reference.

The present invention has an effect that the working fluid can be appropriately evaporated by engine coolant in the Rankine cycle, and is useful for a power generation system and the like.

DESCRIPTION OF SYMBOLS 10 Engine 20 Exhaust passage 24 Heat exchanger 30 Cooling water passage 31a 1st bypass passage 31b 2nd bypass passage 32 Radiator 34 1st adjustment valve 35 2nd adjustment valve 40 Rankine cycle 41 Circulation flow path 42 Pump 43 Evaporator 44 Expander 45 Condenser 80 ECU
S power generation system

Claims

An engine that exhausts exhaust and through which circulating cooling water passes;
An evaporator for evaporating the working fluid having a lower melting point than the cooling water by the cooling water, an expander for expanding the working fluid, a condenser for condensing the working fluid, and circulating the working fluid in the circulation channel Rankine cycle arranged in the order of the circulator to circulate in the flow path,
A first cooling water passage for introducing the cooling water that has passed through the engine into the evaporator;
A second cooling water passage connected to the first cooling water passage after branching from the first cooling water passage;
A heat exchanger provided at a location where the exhaust passage of the exhaust and the second cooling water passage intersect, and recovering the heat of the exhaust into the cooling water of the second cooling water passage;
A power generation system comprising:
A first flow rate adjusting member that is provided at a branch point of the first cooling water passage with the second cooling water passage and adjusts the flow rate of the cooling water flowing from the first cooling water passage to the second cooling water passage; Characterized by comprising,
The power generation system according to claim 1.
A control unit for controlling the operation of the first flow rate adjusting member;
The control unit adjusts the flow rate of the cooling water flowing into the second cooling water passage by operating the first flow rate adjusting member according to the evaporation state of the working fluid in the evaporator.
The power generation system according to claim 2.
A bypass passage that bypasses the evaporator in the first cooling water passage;
A second flow rate adjusting member that adjusts the flow rate of the cooling water introduced into the evaporator and the flow rate of the cooling water flowing into the bypass passage,
The power generation system according to any one of claims 1 to 3.
A controller for controlling the operation of the second flow rate adjusting member;
The control unit operates the second flow rate adjusting member when the engine is warmed up, and causes the cooling water to flow through the bypass passage without introducing the cooling water into the evaporator.
The power generation system according to claim 4.
The controller is configured to operate the second flow rate adjusting member after the engine is warmed to flow cooling water through the evaporator.
The power generation system according to claim 5.