JP2010255604A - Waste heat recovery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste heat recovery device capable of efficiently recovering the cooling waste heat and the exhaust waste heat of an air cooled type internal combustion engine. <P>SOLUTION: An engine system 1 includes: a steam generating means; a steam overheating means; an energy recovering means; a condensing means; and a liquid phase medium supplying means. The heat of air which is heat-exchanged with the engine 100 is used to generate steam, and the generated steam is overheated by using the exhaust waste heat, and the heat energy of the overheated steam can be recovered as kinetic energy. The cooling waste heat and the exhaust waste heat of an air cooled type internal combustion engine can be thereby efficiently recovered. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a waste heat recovery apparatus that recovers waste heat of an internal combustion engine.

  2. Description of the Related Art Conventionally, there is known a waste heat recovery device that recovers cooling waste heat and exhaust waste heat of an internal combustion engine using a Rankine cycle. In such a waste heat recovery device, for example, an expander (for example, a turbine) is driven by the vapor of the liquid phase medium evaporated by exchanging heat with the waste heat of the internal combustion engine, and the thermal energy of the steam is obtained. Some are converted to electrical energy and collected.

  As such a waste heat recovery device, the expander is designed to increase the cooling efficiency of the upstream gas phase part of the condenser connected to the downstream side of the expander than the cooling efficiency of the downstream liquid phase part. Patent Document 1 discloses a technique for improving the condensation performance of discharged steam and reducing the consumption energy of refrigerant evaporation in the evaporator by preventing the overcooling of the condensed refrigerant.

  Further, the exhaust gas of the internal combustion engine and the liquid phase medium are heat-exchanged by the first heat exchanger, and the liquid phase medium heat-exchanged to a constant temperature and the Rankine cycle refrigerant are heat-exchanged by the second heat exchanger. Patent Document 2 discloses a technique for effectively using the heat energy of exhaust gas by converting the heat energy of the refrigerant into mechanical energy by the Rankine cycle.

JP 2002-115504 A JP 2008-095591 A

  In the Rankine cycle power generation, when cooling waste heat of a water-cooled internal combustion engine is used, the amount of heat energy that can be recovered is low because the cooling water temperature of the internal combustion engine is about 80 ° C. in the normal temperature range. Therefore, a means for recovering high thermal energy by exchanging heat of the cooling water of the internal combustion engine with higher temperature exhaust waste heat is used. However, since the antifreezing liquid is used for the cooling water, there is a problem that when the cooling water is boiled, the dissolved substance is deposited and adheres to the apparatus, or the cooling water is altered and deteriorated. On the other hand, measures have been taken to exchange heat with other liquid phase media so as not to boil the cooling water of the internal combustion engine, but since several types of liquid phase media are required, these liquid phase media are sufficient. There is a problem that a long time is required until the Rankine cycle power generation is started after being heated to the temperature.

  Further, since the flow rate and temperature of the exhaust gas of the internal combustion engine greatly fluctuate depending on the operating state, the exhaust waste heat amount changes greatly. Therefore, when steam is generated from the liquid phase medium by exchanging heat with exhaust waste heat, there is a problem that it is difficult to efficiently recover thermal energy depending on the operating state. Furthermore, when heat exchange with the liquid phase medium is performed on the upstream side of the purification catalyst or the like, there is a concern that the purification action of the purification catalyst is reduced due to a decrease in the temperature of exhaust waste heat. When heat is exchanged with the liquid phase medium on the downstream side of the purification catalyst or the like, there is a problem that the amount of heat energy that can be recovered may be low because exhaust waste heat is low temperature.

  However, the conventional technique and the techniques disclosed in Patent Documents 1 and 2 do not include means for solving the above-described problems. Therefore, there is a problem that it is difficult to efficiently recover the cooling waste heat and the exhaust waste heat of the internal combustion engine.

  The present invention has been made in view of such a point, and the internal combustion engine itself is air-cooled, and the cooling waste heat of the internal combustion engine, that is, the heat of the outside air heat-exchanged with the internal combustion engine is used as a heat source. An object of the present invention is to provide a waste heat recovery device capable of recovering cooling waste heat and exhaust waste heat of an internal combustion engine with high efficiency.

In order to achieve the above object, a waste heat recovery apparatus according to the present invention includes a steam generating means for generating steam from a liquid phase medium using heat of outside air after heat exchange with an air-cooled internal combustion engine, and the steam generating means. Steam overheating means for heating the steam generated by using the exhaust heat of the internal combustion engine, energy recovery means for recovering thermal energy of the steam superheated by the steam overheating means as kinetic energy, and the energy recovery means A condensing means for condensing the vapor after passing through the liquid phase medium, and a liquid phase medium supplying means for supplying the liquid phase medium condensed by the condensing means to the vapor generating means. (Claim 1).
With such a configuration, the cooling waste heat and exhaust waste heat of the air-cooled internal combustion engine can be recovered with high efficiency.

In particular, the waste heat recovery apparatus of the present invention may be characterized in that the condensing means condenses the steam into a liquid phase medium using the outside air after heat exchange by the steam generating means (claim). Item 2).
By setting it as such a structure, since the load which introduces the external air for condensing a vapor | steam to a condensing means can be reduced, energy recovery efficiency can be improved.

The waste heat recovery apparatus of the present invention further includes outside air introduction means for introducing outside air different from outside air heat-exchanged with the internal combustion engine into the condensation means, and the condensation means is outside air introduced by the outside air introduction means. To condense the vapor into a liquid phase medium (claim 3).
By setting it as such a structure, since cooler external air can be introduce | transduced into a condensing means, the efficiency which condenses a vapor | steam to a liquid phase medium can be improved. In addition, since the condensed liquid phase medium can be further cooled, the occurrence of cavitation can be suppressed.

  According to the waste heat recovery apparatus of the present invention, steam is generated using the heat of the outside air heat-exchanged with the internal combustion engine, the generated steam is superheated using exhaust waste heat, and the heat energy of the superheated steam is reduced. It can be recovered as kinetic energy. Accordingly, since highly efficient Rankine cycle power generation can be realized, the cooling waste heat and exhaust waste heat of the air-cooled internal combustion engine can be recovered with high efficiency.

It is the block diagram which showed schematic structure of the engine system incorporating the waste heat recovery apparatus of the Example.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for implementing the present invention will be described in detail with reference to the drawings.

  Embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram showing a schematic configuration of an engine system 1 incorporating a waste heat recovery device 51 of the present invention. In addition, in FIG. 1, the arrow has shown the flow direction of refrigerant gas (outside air).

  The waste heat recovery apparatus 51 shown in FIG. 1 forms a Rankine cycle. The engine system 1 includes an engine 100 that is an internal combustion engine, and includes a waste heat recovery device 51 and an ECU (Electronic Control Unit) 10 that comprehensively controls the operation of the engine 100. The engine system 1 also includes a first fan 21 for sending outside air after heat exchange to the steam generator 22 while taking in outside air that cools the engine 100. The engine system 1 includes a second fan 30 for sending outside air that is different from outside air heat-exchanged with the engine 100 to the condenser 25.

The engine 100 is an air-cooled multi-cylinder engine mounted on a vehicle, and each cylinder includes a piston that constitutes a combustion chamber. The piston of each combustion chamber is connected to a crankshaft as an output shaft member via a connecting rod.
The mixed gas flowing into the combustion chamber from the intake port is compressed in the combustion chamber by the upward movement of the piston. The ECU 10 determines the ignition timing based on the position of the piston from the crank angle sensor and the cam shaft rotation phase information from the intake cam angle sensor, and sends a signal to the igniter. The igniter energizes the spark plug with the electric power from the battery at the instructed ignition timing according to the signal from the ECU 10. The spark plug is ignited by electric power from the battery, ignites the compressed mixed gas, expands in the combustion chamber, and lowers the piston. The descending motion is changed to the shaft rotation of the crankshaft through the connecting rod, whereby the engine 100 obtains power.

The exhaust gas after combustion merges in the exhaust passage 31 through the exhaust port when the exhaust valve of each cylinder is opened, passes through the purification catalyst 32, and is discharged to the outside of the engine 100. The purification catalyst 32 is a three-way catalyst that can purify HC, CO, and NOx in the exhaust gas of the engine 100. The purification catalyst 32 occludes NOx when the air-fuel ratio of the inflowing exhaust gas is lean, and reduces and purifies NOx occluded when the air-fuel ratio is stoichiometric or rich with a reducing component (HC or the like). In this case, a plurality of the purification catalysts 32 may be used in combination depending on the displacement of the engine 100, the use area, and the like.
The exhaust passage 31 is provided with an exhaust temperature sensor 33, an A / F sensor, and an O2 sensor. The exhaust passage 31 detects the temperature and air-fuel ratio of exhaust gas discharged from the combustion chamber, and transmits the result to the ECU 10. Further, the purification catalyst 32 is provided with a catalyst temperature sensor 34, detects the temperature of the purification catalyst 32, and transmits the result to the ECU 10. The ECU 10 determines whether or not the purification catalyst 32 is in the activation temperature range based on the detection result of the catalyst temperature sensor 34.

  The engine 100 includes an oil temperature sensor 35 that detects the temperature of the lubricating oil inside the engine 100, and transmits a detection result of the temperature of the lubricating oil to the ECU 10. The ECU 10 recognizes the temperature of the engine 100 based on the detection result of the oil temperature sensor 35, and controls the operation of the first fan 21 described later to adjust the amount of outside air introduced. Thereby, engine 100 can be cooled to an appropriate temperature.

  The waste heat recovery apparatus 51 includes a steam generator 22, a steam superheater 23, a recovery machine 24, a condenser 25, a catch tank 26, and a supply pump 27, which are connected by a distribution path 28. In addition, the waste heat recovery apparatus 51 includes the first fan 21, introduces outside air into the engine 100, and blows outside air heat-exchanged with the engine 100 to the steam generator 22.

The first fan 21 is provided between the engine 100 and the steam generator 22, and cools the engine 100 to an appropriate temperature by introducing outside air into the engine 100 in accordance with an instruction from the ECU 10. The first fan 21 has a configuration in which the fan can be rotated by a power source such as an actuator. The ECU 10 controls the rotational speed of the first fan 21 based on the detection results of the oil temperature sensor 35 and the outside air temperature sensor 36, thereby adjusting the flow rate of outside air introduced from outside the system and cooling the engine 100. As a result, the cooling capacity of the engine 100 can be kept substantially constant, and therefore it is possible to suppress the occurrence of variations in wall temperature, which is a problem of the air-cooled internal combustion engine.
Further, the first fan 21 collects the heat of the outside air by the steam generator 22 by blowing the outside air heat-exchanged with the engine 100 to the steam generator 22. In this case, instead of the first fan 21, other means that can introduce the outside air into the engine 100 and blow the outside air heat-exchanged with the engine 100 to the steam generator 22 may be applied.

An outside air temperature sensor 36 is provided between the engine 100 and the first fan 21. The ECU 10 recognizes the temperature of the outside air that has exchanged heat with the engine 100 based on the detection result of the outside air temperature sensor 36. Then, the ECU 10 controls the operation of the supply pump 27 based on the recognized outside air temperature and the amount of outside air introduced from the operating state of the first fan 21, so that the ECU 10 can appropriately control the waste heat temperature of the engine 100. A sufficient amount of liquid phase medium is supplied to the steam generator 22.
The supply pump 27 corresponds to the liquid medium supply unit of the present invention.

In the steam generator 22, the liquid phase medium supplied from the supply pump 27 circulates, and the liquid phase medium is recovered by collecting the heat of the outside air exchanged with the engine 100 blown from the first fan 21. Generate steam from. The steam generated in the steam generator 22 proceeds to the steam superheater 23 through the distribution path 28. In this case, water is used as the liquid phase medium that circulates inside the waste heat recovery apparatus 51, but the liquid phase medium is not limited to this, and a known liquid phase medium such as Freon or synthetic resin-based organic heat medium oil is applied. You can also.
The steam generator 22 corresponds to the steam generating means of the present invention.

The steam superheater 23 is installed at any location downstream of the purification catalyst 32 on the exhaust gas path from the exhaust passage 31 of the engine 100 through the purification catalyst 32 to the muffler. In the steam superheater 23, steam circulates inside, and the exhaust heat of the exhaust gas of the engine 100 is recovered to superheat the steam and raise the temperature. In this case, the steam superheater 23 may be installed at any location upstream of the purification catalyst 32 on the exhaust gas path. The steam superheated by the steam superheater 23 proceeds to the recovery machine 24 through the distribution path 28.
The steam superheater 23 corresponds to the steam superheating means of the present invention.

The recovery machine 24 includes a turbine and a generator. The turbine is driven by steam flowing from the steam superheater 23, and converts the thermal energy of the steam into kinetic energy. The turbine and the generator have a common drive shaft. When the turbine is driven, power, that is, kinetic energy is transmitted to the generator through the drive shaft. The generator converts the transferred kinetic energy into electrical energy and recovers it. The steam whose thermal energy has been partially recovered by the recovery machine 24 proceeds to the condenser 25 through the distribution path 28.
The recovery machine 24 corresponds to the energy recovery means of the present invention.

The condenser 25 condenses the steam into a liquid phase medium by exchanging heat between the steam that has passed through the recovery machine 24 and recovered a part of the thermal energy and the outside air. The condenser 25 is installed at a position where the external air cooled by the air blown from the first fan 21 and heat exchanged by the steam generator 22 circulates. By adopting such a configuration, it is possible to reduce the load for introducing the refrigerant gas into the condenser 25, and thus it is possible to improve the energy recovery efficiency. The liquid phase medium condensed in the condenser 25 proceeds to the catch tank 26 through the distribution path 28.
The condenser 25 corresponds to the condensing means of the present invention.

  Further, the condenser 25 is provided with a pressure sensor 37 and a temperature sensor 38. The ECU 10 recognizes the vapor pressure inside the condenser 25 based on the detection result of the pressure sensor 37, and recognizes the temperature of the liquid phase medium inside the condenser 25 based on the detection result of the temperature sensor 38. Then, the ECU 10 adjusts the temperature of the outside air introduced into the condenser 25 by controlling the operation of the second fan 30 to be described later based on the recognized pressure of the vapor inside the condenser 25 and the temperature of the liquid phase medium. .

  The catch tank 26 stores the liquid phase medium condensed by the condenser 25. The supply pump 27 pressure-feeds the liquid medium stored in the catch tank 26 to the steam generator 22 through the flow path 28 in accordance with an instruction from the ECU 10. A check valve 29 is provided in the flow path 28 between the supply pump 27 and the steam generator 22. Thereby, it is suppressed that a liquid phase medium flows backward to the supply pump 27 side.

The second fan 30 is provided separately from the circulation path of the outside air that circulates from the first fan 21 to the steam generator 22 and the condenser 25. 25 can be directly installed. The second fan 30 improves the condensation performance of the condenser 25 by introducing cooler outside air into the condenser 25 in accordance with an instruction from the ECU 10. Similar to the first fan 21, the second fan 30 has a configuration in which the fan can be rotated by a power source such as an actuator. The ECU 10 adjusts the flow rate and temperature of the outside air introduced from the outside of the system by controlling the rotational speed of the second fan 30 based on the detection results of the pressure sensor 37 and the temperature sensor 38. In this case, instead of the second fan 30, other means that can directly introduce the outside air different from the outside air heat-exchanged with the engine 100 from the outside of the system to the condenser 25 may be applied.
The second fan 30 corresponds to the outside air introducing means of the present invention.

  The ECU 10 includes a CPU (Central Processing Unit) that performs arithmetic processing, a ROM (Read Only Memory) that stores programs, a RAM (Random Access Memory) that stores data, and an NVRAM (Non Volatile RAM). It is a computer. The ECU 10 reads the detection results of various sensors such as the exhaust temperature sensor 33, the catalyst temperature sensor 34, and the oil temperature sensor 35, and operates the throttle valve, intake valve, exhaust valve, injector, and ignition plug ignition timing. For example, the operation of the engine 100 is controlled in an integrated manner.

Further, the ECU 10 controls the operation of the first fan 21, the second fan 30 and the supply pump 27 based on the detection results of the oil temperature sensor 35, the outside air temperature sensor 36, the pressure sensor 37, and the temperature sensor 38, so that the engine Control for improving the efficiency of 100 waste heat recovery is executed.
Below, an example of the control which ECU10 performs is demonstrated. First, the ECU 10 receives the detection result of the oil temperature sensor 35 and recognizes the temperature of the engine 100. The ECU 10 adjusts the amount of outside air introduced into the engine 100 to a desired amount by controlling the rotational speed of the first fan 21 based on the recognition result of the temperature of the engine 100. By executing this control, the cooling capacity can be adjusted according to the temperature of the engine 100, so that the temperature of the engine 100 can be maintained at an appropriate temperature.

  Subsequently, the ECU 10 receives the detection result of the outside air temperature sensor 36 and recognizes the temperature of the outside air that has exchanged heat with the engine 100. The ECU 10 controls the operation of the supply pump 27 based on the recognition result of the temperature of the outside air and the introduction amount of the outside air estimated from the operating state of the first fan 21, thereby supplying the liquid to be supplied to the steam generator 22 by pressure. Adjust the amount of phase medium to the desired amount. By executing this control, an appropriate amount of liquid phase medium according to the waste heat temperature of the engine 100 can be supplied to the steam generator 22. Therefore, since the steam generation efficiency can be improved, the waste heat of engine 100 can be efficiently recovered.

Then, the ECU 10 receives the detection results of the pressure sensor 37 and the temperature sensor 38 and recognizes the pressure of the steam inside the condenser 25 and the temperature of the liquid phase medium. The ECU 10 controls the rotational speed of the second fan 30 based on the recognition result of the steam pressure and the temperature of the liquid phase medium inside the condenser 25, so that the heat is exchanged in the steam generator 22 and then the condenser 25. Adjust the amount and temperature of outside air introduced to the desired value.
By executing this control, it is possible to introduce into the condenser 25 a refrigerant gas having an appropriate amount and temperature according to the vapor pressure inside the condenser 25 and the temperature of the liquid phase medium. Therefore, the temperature of the liquid phase medium can be adjusted appropriately while improving the steam condensation efficiency, so that the efficiency of waste heat recovery of the engine 100 can be improved.

For example, when the vapor pressure inside the condenser 25 and the temperature of the liquid phase medium are both low, the ECU 10 determines that the condenser 25 has sufficient condensing capacity and that the temperature of the liquid phase medium is appropriate. The rotation of the second fan 30 is stopped while maintaining the rotation speed of the first fan 21.
On the other hand, when the pressure of the steam inside the condenser 25 is high, the ECU 10 determines that the condenser 25 has insufficient condensing capacity, and rotates the second fan 30 while maintaining the rotational speed of the first fan 21. Introduce cooler outside air. By this control, a lower temperature refrigerant gas can be introduced into the condenser 25, so that the condensation efficiency of the condenser 25 can be improved.
When the temperature of the liquid medium is high, the ECU 10 determines that cavitation may occur when the supply pump 27 pumps and supplies the liquid medium, and maintains the rotation speed of the first fan 21. The second fan 30 is rotated to introduce cooler outside air. By this control, a lower temperature refrigerant gas can be introduced into the condenser 25, so that the temperature of the liquid phase medium in the condenser 25 can be lowered, and the cavitation of the liquid phase medium when pumped is supplied. Occurrence can be suppressed.
When the vapor pressure inside the condenser 25 and the temperature of the liquid phase medium are both high, the ECU 10 does not have sufficient condensing capacity of the condenser 25, and the temperature of the liquid phase medium is not appropriate, which may cause cavitation. The second fan 30 is rotated significantly while maintaining the rotational speed of the first fan 21 to introduce cooler outside air. Since the amount of refrigerant gas introduced into the condenser 25 can be increased by this control, the temperature of the liquid phase medium inside the condenser 25 is lowered and cavitation is generated while improving the condensation efficiency of the condenser 25. Can be suppressed.

  Thus, when the condensation performance of the condenser 25 is sufficient and the temperature of the liquid phase medium in the condenser 25 is low, only the first fan 21 is operated to condense the outside air for condensing the steam. The load to be introduced can be reduced. On the other hand, when the condensation performance of the condenser 25 is not sufficient, or when the temperature of the liquid phase medium inside the condenser 25 is high, the first fan 21 and the second fan 30 are operated to condense cooler outside air. It can be introduced into the vessel 25. Therefore, the occurrence of cavitation in the liquid phase medium can be suppressed while improving the vapor condensation efficiency.

  By executing the above control, it is possible to realize highly efficient Rankine cycle power generation using the heat of the outside air exchanged with the engine 100, so that the cooling waste heat and exhaust waste heat of the air-cooled internal combustion engine are increased. It can be recovered efficiently.

  As described above, the engine system 1 of the present embodiment exchanges heat with the internal combustion engine by including the steam generation means, the steam superheating means, the energy recovery means, the condensation means, and the liquid phase medium supply means. Since steam can be generated using the heat of the outside air, the generated steam can be superheated using exhaust waste heat, and the heat energy of the overheated steam can be recovered as kinetic energy. Waste heat and exhaust waste heat can be recovered with high efficiency.

  The engine system 1 of the present embodiment also includes outside air introduction means for introducing outside air different from outside air heat-exchanged with the internal combustion engine into the condensation means, and the condensation means uses the outside air introduced by the outside air introduction means to cause the condensation means to generate steam. By executing the control to condense into the liquid phase medium, it is possible to introduce a lower temperature refrigerant gas into the condensing means, thereby suppressing the occurrence of cavitation in the liquid phase medium while improving the vapor condensing efficiency. it can.

  The above embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to these, and various modifications and changes can be made within the scope of the gist of the present invention described in the claims.

For example, the waste heat recovery apparatus of the present invention may be applied to a water-cooled internal combustion engine. In that case, the waste heat of the internal combustion engine can be effectively used by introducing the outside air heat-exchanged with the radiator into the steam generator.
Further, as the outside air introduced into the system, air outside the system is used, but the outside air is not limited to this and a known cooling medium can be used.

1 Engine system 10 ECU
21 First fan 22 Steam generator (steam generating means)
23 Steam superheater (steam superheater)
24 Recovery machine (energy recovery means)
25 Condenser (condensing means)
26 Catch tank 27 Supply pump (liquid phase medium supply means)
28 Flow path 29 Check valve 30 Second fan (outside air introduction means)
31 exhaust passage 32 purification catalyst 33 exhaust temperature sensor 34 catalyst temperature sensor 35 oil temperature sensor 36 outside air temperature sensor 37 pressure sensor 38 temperature sensor 51 waste heat recovery device 100 engine

Claims (3)

Steam generating means for generating steam from the liquid phase medium using heat of the outside air after heat exchange with the air-cooled internal combustion engine;
Steam overheating means for heating the steam generated by the steam generation means using exhaust heat of the internal combustion engine;
Energy recovery means for recovering thermal energy of the steam superheated by the steam superheating means as kinetic energy;
Condensing means for condensing the vapor after passing through the energy recovery means into a liquid phase medium;
A liquid phase medium supplying means for supplying the liquid phase medium condensed by the condensing means to the vapor generating means;
A waste heat recovery apparatus comprising:   The waste heat recovery apparatus according to claim 1, wherein the condensing unit condenses the vapor into a liquid phase medium using outside air after heat exchange by the vapor generating unit. An outside air introduction means for introducing outside air different from outside air heat-exchanged with the internal combustion engine into the condensing means;
The waste heat recovery apparatus according to claim 2, wherein the condensing unit condenses the vapor into a liquid phase medium using the outside air introduced by the outside air introducing unit.

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