JP2011132922A - Waste heat recovery device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize early warming up of an engine for quickly starting waste heat recovery and improving fuel economy. <P>SOLUTION: The waste heat recovery device 100 includes an engine body 1 which is cooled by boiling of a cooling medium inside, an overheat evaporator 7 which performs heat exchange between the cooling medium flowing from the engine body 1 side through a cooling medium supply passage 3 and the exhaust air exhausted from the engine body 1, and a turbine part 9 which recovers energy from the vaporized cooling medium which passes through the overheat evaporator 7. The waste heat recovery device 100 further includes a cooling medium recovery passage 10 which recirculates the cooling medium from which the energy is recovered by the turbine part 9 to the engine body 1 side. A solenoid valve 14 is arranged in the cooling medium supply passage 3, and a unidirectional valve 15 is arranged in the cooling medium recovery passage 10. The waste heat recovery device 100 is divided into the engine body 1 and the overheat evaporator 7 by the solenoid valve 14 and the unidirectional valve 15 during warming up of the engine body 1. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a waste heat recovery apparatus.

  2. Description of the Related Art Conventionally, a waste heat recovery apparatus that recovers waste heat associated with operation of an internal combustion engine (engine) using a Rankine cycle is known. In such a waste heat recovery device, for example, boiling cooling is performed by using a water cooling cooling system of the engine as a closed structure, and an expander (impulsive turbine) is driven by cooling water vaporized by waste heat in the engine, that is, steam. In some cases, the heat energy of the steam is converted into electric energy and recovered. For example, Patent Document 1 discloses an improved version of such a waste heat recovery apparatus.

JP 2009-103060 A

  By the way, in order to perform boiling cooling of the engine, the cooling water passage inside the waste heat recovery apparatus including the engine body is sealed. The inside of the sealed cooling water passage is in a low pressure state at the time of cold start. In the low pressure state, the saturation temperature becomes low (for example, about 10 kPa ABS and about 46 ° C.), and the boiling of the cooling water starts even though the temperature is low. That is, although the warm-up has not been completed, boiling cooling is started. Further, the steam flowing into the condenser provided in the waste heat recovery device is further cooled despite the low temperature. In this case, the waste heat of the engine is released to the atmosphere, and the engine does not warm up easily. If engine warm-up does not proceed, fuel consumption will deteriorate and catalyst warm-up will also be delayed. Further, as the engine warms up and the temperature in the cooling water passage rises, the pressure in the cooling water passage rises. Accordingly, the operation of the Rankine cycle is delayed if the pressure rise in the cooling water passage is delayed with the delay in the temperature rise in the cooling water passage. If the operation of the Rankine cycle is delayed, the waste heat recovery efficiency will also decrease.

  Therefore, the waste heat recovery apparatus disclosed in this specification has a problem of promptly starting the recovery of waste heat and early warming up of the engine for improving fuel efficiency.

  In order to solve this problem, the waste heat recovery apparatus disclosed in the present specification includes an engine body that is cooled by boiling a cooling medium therein, and the cooling medium that flows from the engine body side through the cooling medium supply path. A heat exchange part that exchanges heat between the engine and the exhaust discharged from the engine body, an energy recovery part that recovers energy from the vaporized cooling medium that has passed through the heat exchange part, and an energy recovery part The cooling medium recovery path for recirculating the cooling medium after being recovered to the engine body side, the first blocking means provided in the cooling medium supply path, and the cooling medium recovery path A second shut-off means, and the engine main body and the heat exchanging section are separated by the first shut-off means and the second shut-off means when the engine main body is warmed up. It is set to.

  Such a waste heat recovery apparatus circulates the cooling medium only on the engine body side at the time of warming up, so that early warming up can be completed. Further, the pressure of the cooling medium inside the waste heat recovery device can be increased early as the engine body warms up early. By raising the pressure of the cooling medium, the saturation temperature rises, and the boiling cooling state before the completion of warm-up can be suppressed. By suppressing boiling cooling, warm-up completion is accelerated. Further, when the temperature and pressure of the cooling medium rise early, energy can be recovered quickly, and the efficiency of waste heat recovery is improved. Furthermore, the friction reduction is realized at an early stage by completing the early warm-up of the engine body. As a result, fuel efficiency is improved.

  In such a waste heat recovery apparatus, a gas-liquid separator can be disposed in the cooling medium supply path. And the said 1st interruption | blocking means can be arrange | positioned between the said heat exchange part and the said gas-liquid separator. As a result, the gas-liquid separator is incorporated into the coolant circulation circuit on the engine body side during warm-up.

  Further, in such a waste heat recovery apparatus, when the temperature and / or pressure of the cooling medium upstream of the first shut-off means is equal to or higher than a predetermined value, the first shut-off means is opened from the engine body side. It can be set as the structure provided with the control part which accept | permits the distribution | circulation of the said cooling medium to the said heat exchange part side.

  Thereby, inflow of the cooling medium in a state where temperature and pressure are low and efficient waste heat recovery in the energy recovery unit cannot be performed is blocked. As a result, the removal of heat by the cooling medium that cannot contribute to efficient waste heat recovery at the time of warm-up is suppressed, so that efficient waste heat recovery can be achieved early. it can. Thereby, efficient waste heat recovery can be performed.

  In such a waste heat recovery apparatus, the second blocking means allows the cooling medium to flow from the heat exchange part side to the engine body side, and the engine body side to the heat exchange part side. It can be a one-way valve that blocks the flow of the cooling medium. Inside the waste heat recovery apparatus, a path for the cooling medium is formed in a loop shape. In the waste heat recovery apparatus having a loop-shaped cooling medium path, the second blocking means divides the engine body side and the heat exchanging portion side together with the first blocking means. Here, since the flow direction of the cooling medium is a fixed direction, a one-way valve can be used as means for avoiding the back flow of the cooling medium. A vane-type pump having a backflow prevention function may be employed as a pump for pumping the cooling medium to avoid backflow of the cooling medium.

  According to the waste heat recovery apparatus disclosed in the present specification, it is possible to warm up the engine early, to quickly start waste heat recovery and to improve fuel efficiency.

FIG. 1 is a schematic configuration diagram of a waste heat recovery apparatus according to an embodiment. FIG. 2 is a flowchart illustrating an example of control of the waste heat recovery apparatus according to the embodiment.

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

  A schematic configuration of the waste heat recovery apparatus 100 will be described with reference to FIG. The waste heat recovery apparatus 100 includes an engine body 1 that is cooled by boiling a cooling medium therein. The engine body 1 includes a cylinder block 1a and a cylinder head 1b. A water jacket is formed in the cylinder block 1a and the cylinder head 1b, and the engine body 1 is cooled by boiling the cooling medium in the water jacket. The engine body 1 further includes an exhaust pipe 2. An exhaust catalyst is incorporated in the exhaust pipe. One end of a cooling medium supply path 3 is connected to the cylinder head 1 b of the engine body 1. The cooling medium warmed by the engine body 1 flows into the cooling medium supply path 3.

  A gas-liquid separator 4 is disposed in the cooling medium supply path 3. The cooling medium flowing into the gas-liquid separator 4 from the engine body 1 side in the gas-liquid mixed state is separated into a gas phase and a liquid phase in the gas-liquid separator 4. One end of the coolant circulation path 5 is connected to the lower end of the gas-liquid separator 4. The other end of the cooling medium circulation path 5 is connected to the cylinder block 1a. The cooling medium circulation path 5 is provided with a first water pump 6 that pumps a liquid cooling medium into the engine body 1. The first water pump 6 is a so-called mechanical type, and uses a crankshaft provided in the engine body 1 as a drive source.

  The other end of the cooling medium supply path 3 is connected to a superheat evaporator 7 corresponding to a heat exchange unit. The superheat evaporator 7 is provided with an evaporator 7a on the lower side and an overheater 7b on the upper side. The cooling medium supply path 3 is connected to the evaporation unit 7a. The exhaust pipe 2 is drawn into the superheated evaporator 7. The exhaust pipe 2 passes through the superheated evaporator 7 so that the exhaust gas flowing through the exhaust pipe 2 passes through the superheated portion 7b and the evaporator 7a in this order. Thus, the superheat evaporator 7 performs heat exchange between the cooling medium flowing from the engine body 1 side through the cooling medium supply path 3 and the exhaust discharged from the engine body 1. Thereby, while generating amount of steam increases, the superheat degree of steam improves and waste heat recovery efficiency improves. A steam discharge pipe 7c is provided at the upper end of the superheated part 7b.

  A turbine section 9 corresponding to an energy recovery section that recovers energy from the vaporized cooling medium that has passed through the superheat evaporator 7 is disposed downstream of the superheat evaporator 7. The turbine unit includes an impulse turbine, and is driven by steam injected from a nozzle 9a provided at the tip of the steam discharge pipe 7c. The rotational force of the impulse turbine is used to assist the rotation of the crankshaft included in the engine body 1 or to drive the generator. Thereby, recovery of waste heat is performed.

  A cooling medium recovery path 10 is provided on the downstream side of the turbine unit 9 to recirculate the cooling medium after energy is recovered in the turbine unit 9 to the engine body side. One end of the cooling medium recovery path 10 is connected to the turbine unit 9. The other end of the cooling medium recovery path 10 is connected to the upstream side of the first water pump 6 in the cooling medium circulation path 5. A condenser 11 is disposed in the cooling medium recovery path 10. The condenser 11 cools and condenses the vaporized cooling medium, and returns the cooling medium to a liquid state. A first condensing tank 11a is provided at the lower end of the condenser 11, and the condensed cooling medium is temporarily stored. A second condensing tank 12 is disposed downstream of the condenser 11 in the cooling medium recovery path 10. The second condensing tank 12 stores the liquid cooling medium once stored in the first condensing tank 11a.

  A second water pump 13 is disposed downstream of the second condensing tank 12 in the cooling medium recovery path 10. The second water pump 13 is an electric pump. When the second water pump 13 is activated, the cooling medium in the second condensing tank 12 is supplied to the cooling medium circulation path 5.

  As described above, the waste heat recovery apparatus 100 includes a path through which the cooling medium circulates. The waste heat recovery apparatus 100 includes an electromagnetic valve 14 corresponding to the first shut-off means disposed in the cooling medium supply path 3. Specifically, the electromagnetic valve 14 is disposed between the gas-liquid separator 4 and the superheated evaporator 7.

  In addition, the waste heat recovery apparatus 100 includes a one-way valve 15 that corresponds to a second shut-off unit disposed downstream of the second water pump 13 in the cooling medium recovery path 10. The waste heat recovery apparatus 100 includes a pressure sensor 17 and a temperature sensor 18 in the gas-liquid separator 4. The pressure sensor 17 measures the pressure of the coolant on the upstream side of the electromagnetic valve 14, that is, on the side closer to the engine body 1 than the electromagnetic valve 14. The temperature sensor 18 measures the temperature of the coolant on the upstream side of the electromagnetic valve 14, that is, on the side closer to the engine body 1 than the electromagnetic valve 14. A float type liquid level sensor 19 is provided in the gas-liquid separator 4. The waste heat recovery apparatus 100 includes an ECU (Electronic control unit) 20 corresponding to a control unit. The ECU 20 is electrically connected to the second water pump 13 and the electromagnetic valve 14, respectively. The ECU 20 is electrically connected to the pressure sensor 17, the temperature sensor 18, and the liquid level sensor 19.

  The second water pump 13 is driven and controlled by the ECU 20. Specifically, when the liquid level of the cooling medium in the gas-liquid separator 4 is lowered by the liquid level sensor 19, a drive command is issued by the ECU 20, and the liquid cooling medium is supplied from the second condensation tank 12 to the engine body. Pump to 1 side. Thereby, it is possible to avoid a situation where the liquid-phase cooling medium is insufficient in the engine body 1.

  The electromagnetic valve 14 is controlled to be opened and closed by the ECU 20. Specifically, when the temperature and / or pressure of the cooling medium is equal to or higher than a predetermined value, the electromagnetic valve 14 is opened to allow the cooling medium to flow from the engine body 1 side to the superheated evaporator 7 side.

  On the other hand, the valve 15 allows the cooling medium to flow from the superheated evaporator 7 side to the engine main body 1 side, and blocks the flow of the cooling medium from the engine main body 1 side to the superheated evaporator 7 side. That is, when the second water pump 13 is operated, only the flow of the cooling medium from the superheated evaporator 7 side to the engine body 1 side is allowed. Therefore, unless the second water pump 13 receives an operation command from the ECU 20, the one-way valve 15 is in a state in which the cooling medium recovery path 10 is divided.

  The waste heat recovery apparatus 100 divides the engine body 1 and the superheated evaporator 7 by the electromagnetic valve 14 and the one-way valve 15 when the engine body 1 is warmed up. Thereby, a sealed circuit is formed when the engine body 1 is warmed up. When the engine body 1 is warmed up, the cooling medium is closed in a sealed circuit, that is, the first water pump 6, the cylinder block 1 a, the cylinder head 1 b, the gas-liquid separator 4, and the first water pump 6 again. Circulate in the circuit. As a result, the temperature of the cooling medium is quickly raised by the heat generated by the engine body 1, and warm-up is completed early. Moreover, since the pressure in the sealed circuit increases, the saturation temperature of the cooling medium increases. And the boiling of the cooling medium in the engine main body 1 is suppressed. As a result, cooling in a state where warm-up has not been completed is avoided. By completing the warm-up of the engine body 1 at an early stage, friction reduction is realized at an early stage. As a result, fuel efficiency is improved.

  Moreover, since the inflow of the cooling medium to the superheated evaporator 7 side is avoided, the temperature drop of the exhaust gas flowing through the exhaust pipe 2 is also avoided. As a result, the exhaust catalyst can be warmed up early.

  Furthermore, since the inflow of the cooling medium to the condenser 11 is also avoided, the release of heat from the condenser 11 during warm-up is also avoided.

  Warm-up is completed early and the cooling medium reaches a state in which the cooling medium can drive the turbine unit 9 at an early stage, thereby improving the waste heat recovery efficiency.

  Next, an example of the control of the waste heat recovery apparatus 100 will be described with reference to the flowchart shown in FIG.

  When the engine body 1 is started, the ECU 20 acquires data from the pressure sensor 17 and the temperature sensor 18 and determines whether or not the engine is in a warm-up completion state. Specifically, in step S1, it is determined whether or not the pressure measurement value P by the pressure sensor 17 is equal to or greater than a predetermined pressure value P0. If YES is determined in step S1, the process proceeds to step S3. In step S <b> 3, the ECU 20 issues an open command to the electromagnetic valve 14. On the other hand, if NO is determined in step S1, the process proceeds to step S2. If it is determined in step S2 that the temperature measurement value T measured by the temperature sensor 17 is equal to or higher than the predetermined temperature value T0 in step S2, the process proceeds to step S3. In step S3, as described above, the ECU 20 issues an open command to the electromagnetic valve 14. On the other hand, when NO is determined in step S2, the steps from step S1 are repeated again.

  Here, the predetermined pressure value P0 and temperature value T0 are both set as threshold values for determining the completion of warm-up. In this embodiment, it is determined that the warm-up has been completed when the pressure or temperature of the cooling medium is equal to or higher than a predetermined value. It may be determined that the warm-up is complete when both the pressure value and the temperature value are equal to or greater than a predetermined value. Alternatively, only one of the pressure sensor and the temperature sensor may be provided, and the completion of warm-up may be determined based on data acquired by the sensor.

  As described above, according to the waste heat recovery apparatus 100 of the present embodiment, it is possible to warm up the engine early, to quickly start the recovery of waste heat and to improve fuel efficiency.

  The above-described embodiments are merely examples for carrying out the present invention, and the present invention is not limited thereto. Various modifications of these embodiments are within the scope of the present invention. It is apparent from the above description that various other embodiments are possible within the scope.

DESCRIPTION OF SYMBOLS 1 ... Engine main body 1a ... Cylinder block 1b ... Cylinder head 2 ... Exhaust pipe 3 ... Cooling medium supply path 4 ... Gas-liquid separator 5 ... Cooling medium circulation path 6 ... 1st water pump (W / P)
7 ... Superheated evaporator (heat exchanger)
7a ... evaporation part 7b ... superheat part 9 ... turbine part (energy recovery part)
DESCRIPTION OF SYMBOLS 10 ... Cooling medium collection | recovery path 11 ... Condenser 11a ... 1st condensation tank 12 ... 2nd condensation tank 13 ... 2nd water pump (W / P)
14 ... Solenoid valve (first blocking means)
15 ... One-way valve (second shut-off means)
17 ... Pressure sensor 18 ... Temperature sensor 19 ... Liquid level sensor 20 ... ECU (control unit)
100 ... Waste heat recovery device

Claims (4)

An engine body cooled by boiling the cooling medium inside,
A heat exchanging unit that performs heat exchange between the cooling medium flowing in from the engine body through the cooling medium supply path and the exhaust discharged from the engine body;
An energy recovery unit that recovers energy from the vaporized cooling medium that has passed through the heat exchange unit;
A cooling medium recovery path for recirculating the cooling medium after energy is recovered in the energy recovery unit to the engine body side;
First blocking means disposed in the cooling medium supply path;
Second blocking means disposed in the cooling medium recovery path;
With
A waste heat recovery apparatus, wherein the engine main body and the heat exchanging section are separated by the first shut-off means and the second shut-off means when the engine main body is warmed up.   The gas-liquid separator is disposed in the cooling medium supply path, and the first shut-off means is disposed between the heat exchange unit and the gas-liquid separator. Waste heat recovery device.   When the temperature and / or pressure of the cooling medium on the upstream side of the first shut-off means is equal to or higher than a predetermined value, the first shut-off means is opened, and The waste heat recovery apparatus according to claim 1, further comprising a control unit that allows distribution.   The second blocking means is a one-way valve that allows the flow of the cooling medium from the heat exchange part side to the engine body side and blocks the flow of the cooling medium from the engine body side to the heat exchange part side. The waste heat recovery apparatus according to claim 1, wherein the heat recovery apparatus is a waste heat recovery apparatus.

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