JP2008008224A - Waste heat utilization device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a waste heat utilization device for using waste heat in multiple ways in an internal combustion engine for performing the supercharging of intake air and effectively using the waste heat. <P>SOLUTION: The waste heat utilization device includes a Rankine cycle 200 for heating an operating fluid within a cycle by heat exchangers 211, 212 by waste heat related to the internal combustion engine 10, expanding the heated operating fluid by an expansion machine 220 and collecting mechanical energy, and condensing and liquefying the expanded operating fluid by a condenser 230. The internal combustion engine 10 is equipped with a supercharger 40 for pressurizing intake air, and the heat exchangers 211, 212 include a first heat exchanger 211 for heating the operating fluid by the stable waste heat from the internal combustion engine 10 as a heat source, and a second heat exchanger 212 for heating the operating fluid by heat from the intake air pressurized by the supercharger 40 as a heat source. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a waste heat utilization device that recovers power by utilizing waste heat of an internal combustion engine such as a vehicle.

As a conventional waste heat utilization apparatus, for example, as shown in Patent Document 1, an apparatus using an exhaust gas of a gas turbine as a heat source for a Rankine cycle is known. In Patent Document 1, as the heat source of the Rankine cycle, in addition to waste heat that is normally lost to the atmosphere, heat of the coolant circulating in the radiator, heat of the compressed combustion air incident on the intercooler , Geothermal, flare exhaust gas heat and the like.
JP 2006-506570 A

  However, in the above-mentioned Patent Document 1, it is only described that the above various heats can be used as a heat source for the Rankine cycle in addition to the exhaust gas heat, and no specific description is given. . For example, in the case of a vehicle, when the heat of compressed combustion air is considered as the heat source of the Rankine cycle, the heat of the compressed combustion air greatly fluctuates according to the running conditions of the vehicle, and as a stable Rankine cycle heat source. It becomes difficult to use.

  Further, Patent Document 1 does not disclose the idea of using waste heat more effectively by using the various heats in combination.

  In view of the above problems, an object of the present invention is to provide a waste heat utilization device that enables effective waste heat utilization by using waste heat in an internal combustion engine that supercharges intake air in a composite manner. .

  In order to achieve the above object, the present invention employs the following technical means.

  In the first aspect of the present invention, the working fluid in the cycle is heated by the heat exchangers (211 and 212) by the waste heat related to the internal combustion engine (10), and the heated working fluid is heated by the expander (220). In a waste heat utilization apparatus having a Rankine cycle (200) that expands and recovers mechanical energy and condenses and liquefies the expanded working fluid in a condenser (230), the internal combustion engine (10) pressurizes the intake air A supercharger (40) is provided, and the heat exchangers (211 and 212) are a first heat exchanger (211) that heats the working fluid using stable waste heat from the internal combustion engine (10) as a heat source, And a second heat exchanger (212) for heating the working fluid using the heat of the intake air pressurized by the supercharger (40) as a heat source.

  Thereby, the working fluid is heated by the first heat exchanger (211) using the stable waste heat from the internal combustion engine (10), and the stable Rankine cycle (200) can be operated. Since the working fluid can be further heated by the second heat exchanger (212) using the heat of the intake air, the thermal energy of the working fluid is increased and mechanical energy that can be recovered by the expander (220). Can be increased. In general, the waste heat utilization apparatus (100) that enables effective waste heat utilization can be obtained.

  The stable waste heat from the internal combustion engine (10) can be the heat of the coolant for cooling the internal combustion engine (10), as in the second aspect of the invention.

  In the invention according to claim 2, in the invention according to claim 3, the second heat exchanger (212) is disposed upstream of the working fluid flow of the first heat exchanger (211). It is a feature.

  Thereby, first, the working fluid can be heated by the second heat exchanger (212). When the coolant temperature is low as at the start of the internal combustion engine (10), the working fluid heated by the second heat exchanger (212) is used using the first heat exchanger (211) as a radiator. The heat can be used to heat the coolant. Therefore, early warm-up of the internal combustion engine (10) can be achieved.

  The invention described in claim 4 is characterized in that switching means (250) for switching the inflow sequence of the working fluid to the first heat exchanger (211) and the second heat exchanger (212) is provided.

  Thus, when the working fluid is switched so as to flow in the order from the second heat exchanger (212) to the first heat exchanger (211), the internal combustion engine (10) can be moved as early as the invention according to claim 3. Warm-up can be achieved. Conversely, when switching is made so that the working fluid flows in the order from the first heat exchanger (211) to the second heat exchanger (212), the temperature of the heat source with respect to the working fluid may increase in order. Therefore, a sufficient temperature difference between the working fluid and each heat source can be secured, and effective heat exchange (heating of the working fluid) can be performed.

  In the invention according to claim 5, when the internal combustion engine (10) is operated, the Rankine cycle (200) is always operated, and the second heat exchanger (212) is operated with the pressurized suction. It also functions as an intercooler (13) that cools the air.

  Thereby, the intercooler (13) normally set for cooling the intake air can be eliminated.

  The invention according to claim 6 is characterized by comprising a refrigeration cycle (300) formed by sharing the condenser (230) with the Rankine cycle (200) and circulating the working fluid in the cycle. Yes.

  Accordingly, the Rankine cycle (200) and the refrigeration cycle (300) can be configured by sharing a part of the working fluid and the circuit.

  In addition, the waste heat utilization apparatus (100) of this invention is suitable for use for vehicles provided with the engine (10) as an internal combustion engine (10) like the invention of Claim 7.

  Incidentally, the reference numerals in parentheses of each means described above are an example showing the correspondence with the specific means described in the embodiments described later.

(First embodiment)
A first embodiment of the present invention is shown in FIG. 1, and a specific configuration will be described first. The waste heat utilization apparatus 100 of this embodiment is applied to a vehicle that uses an engine 10 (corresponding to the internal combustion engine of the present invention) as a drive source. The waste heat utilization apparatus 100 has a Rankine cycle 200 that uses waste heat related to the engine 10 as a heat source.

  The engine 10 is water-cooled, and a radiator circuit 20 that cools the engine 10 by circulation of engine coolant (corresponding to the coolant of the present invention), and a heater circuit that heats conditioned air using the engine coolant (hot water) as a heat source. 30. The engine 10 is provided with an alternator (not shown) that is driven by the driving force of the engine 10 to generate electric power. The electric power generated by the alternator is charged in a battery (not shown), and the electric power charged in the battery is supplied to a vehicle electric load (headlamp, wiper, audio, etc.).

  A radiator 21 is provided in the radiator circuit 20. The radiator 21 is disposed in front of the vehicle engine room (behind the grill), and cools engine coolant circulated by the hot water pump 22 by heat exchange with outside air flowing in from the grill. Here, the hot water pump 22 is a mechanical pump driven by the engine 10. The hot water pump 22 may be an electric pump driven by an electric motor.

  The radiator circuit 20 is provided with a radiator bypass passage 23 through which the cooling water flows around the radiator 21, and the cooling water amount flowing through the radiator 21 by the thermostat 24 and the cooling through the radiator bypass passage 23. The amount of water is adjusted. Thus, during steady operation of the engine 10, the temperature of the engine coolant on the outlet side of the engine 10 is maintained around 90 ° C.

  The heater circuit 30 is formed so as to branch from the radiator circuit 20, pass through the heater core 31, and then merge with the radiator circuit 20, and engine cooling water is circulated by the hot water pump 22. . The heater circuit 30 is provided with a heater core 31 for heating the conditioned air using engine cooling water (hot water) as a heat source. The heater core 31 is disposed in an air conditioning case of an air conditioning unit (not shown), and heats conditioned air blown by a blower (not shown) by heat exchange with engine cooling water.

  The engine 10 includes a supercharger 40 that pressurizes combustion air (hereinafter, intake air) sucked from the suction pipe 11. The supercharger 40 has an exhaust turbine 41 and a compressor 42 connected to the exhaust turbine 41. In the supercharger 40, the exhaust turbine 41 is rotationally driven by the exhaust gas exhaust force exhausted from the exhaust pipe 12 of the engine 10, and the compressor 42 is rotationally driven as the exhaust turbine 41 is rotationally driven. The compressor 42 pressurizes the intake air sucked from the suction pipe 11 of the engine 10 and supplies it to the engine 10.

  In the suction pipe 11, an intercooler 13 is provided between the compressor 42 and the engine 10. The intercooler 13 is disposed adjacent to the radiator 21 in the front (rear of the grill) in the vehicle engine room, and heat of the intake air pressurized by the compressor 42 and heated to the outside air flowing in from the grill. Cool by replacement. The intake air rises to around 200 ° C. by the pressurization of the compressor 42, but is cooled to around 60 ° C. (predetermined cooling temperature) by the intercooler 13.

  The Rankine cycle 200 collects waste heat energy (heat energy of engine cooling water and heat energy of intake air) generated in the engine 10 and converts the waste heat energy into electric energy and uses it. . Hereinafter, the Rankine cycle 200 will be described.

  The Rankine cycle 200 includes a heater (corresponding to the first heat exchanger of the present invention) 211, a heat exchanger (corresponding to the second heat exchanger of the present invention) 212, an expander 220, a condenser 230, and a pump 240. These are sequentially connected to form a closed circuit, and a refrigerant (corresponding to the working fluid of the present invention) is circulated by the pump 240 in the closed circuit. The pump 240 is an electric pump that uses an electric motor (not shown) as a drive source, and its operation is controlled by a control device (not shown). In the present embodiment, HFC134a is used as the refrigerant of Rankine cycle 200.

  A combination of the heater 211 and the heat exchanger 212 corresponds to the heat exchanger of the present invention, and performs basic refrigerant heating in the Rankine cycle 200. That is, the heater 211 heats the refrigerant by exchanging heat between the refrigerant sent from the pump 240 and the high-temperature engine cooling water flowing through the radiator circuit 20. The heat exchanger 212 is disposed on the downstream side of the refrigerant flow of the heater 211, and the refrigerant flowing out of the heater 211 and the intake air pressurized by the supercharger 40 (compressor 42). The refrigerant is further heated by exchanging heat between them.

  The expander 220 is a fluid device that generates a rotational driving force by the expansion of the superheated steam refrigerant heated by the heater 211 and the heat exchanger 212. A power generator (not shown) is connected to the expander 220, and the power generator is operated by the driving force of the expander 220, and the power generated by the power generator is charged to the battery via a control circuit (inverter) (not shown). It has come to be.

  The refrigerant that flows out of the expander 220 reaches the condenser 230. The condenser 230 is a heat exchanger disposed on the upstream side of the outside air flow of the radiator 21 in the vehicle engine room, and condenses and liquefies the refrigerant by heat exchange with the outside air flowing in from the grill. The refrigerant liquefied by the condenser 230 is sent to the heater 211 by the pump 240 as described above.

  Hereinafter, the operation of the waste heat utilization apparatus 100 according to the present embodiment will be described. When the engine coolant temperature on the outlet side of the engine 10 becomes equal to or higher than a predetermined temperature as the engine 10 is operated, there is sufficient waste heat obtained from the engine coolant, and the temperature of the engine coolant flowing into the heater 211 is sufficiently high. As a result, the pump 240 is operated by a control device (not shown) and the Rankine cycle 200 is operated. Further, as the engine 10 is operated, the supercharger 40 is operated, and the intake air is pressurized by the compressor 42.

  When the Rankine cycle 200 is operated, the liquid refrigerant on the condenser 230 side is pressurized by the pump 240 and sent to the heater 211. The liquid refrigerant is heated by the engine coolant in the heater 211, further heated by the intake air in the heat exchanger 212, and sent to the expander 220 as superheated vapor refrigerant.

  The intake air is cooled by heating the refrigerant in the heat exchanger 212, further cooled to a predetermined cooling temperature (around 60 ° C.) by the intercooler 13, and sucked into the engine 10.

  In the expander 220, the superheated vapor refrigerant is expanded and reduced in an isentropic manner, and part of the heat energy and pressure energy is converted into a rotational driving force. A generator (not shown) is activated by the rotational driving force extracted by the expander 220, and the generator generates power. The electric power obtained by the generator is charged to the battery via the control circuit and used for the operation of various auxiliary machines. Note that the refrigerant decompressed by the expander 220 is condensed by the condenser 230 and sucked into the pump 240 again.

  In the heater core 31, the conditioned air to be blown is heated by engine cooling water (hot water) to heat the passenger compartment.

  As described above, in the present embodiment, the coolant is heated by the heater 211 using the heat of the engine cooling water as the stable waste heat from the engine 10, and the Rankine cycle 200 can be stably operated. And since the refrigerant | coolant can be further heated with the heat exchanger 212 using the heat | fever of intake air, the thermal energy of a refrigerant | coolant can be raised and the mechanical energy which can be collect | recovered with the expander 220 can be increased. Therefore, the amount of power generation in the generator can be increased, the operation frequency of the alternator can be reduced, and the load on the engine 10 can be reduced. In general, the waste heat utilization apparatus 100 that enables effective waste heat utilization can be obtained.

  In addition, since the intake air is cooled in the heat exchanger 212, the size of the intercooler 13 can be reduced accordingly. Since the heat exchanger 212 exchanges heat between the intake air and the refrigerant, unlike the radiator 21 and the condenser 230, a specific installation area in which outside air easily flows is not required in the engine room. . Therefore, the mountability of the radiator 21 and the condenser 230 can be improved as the intercooler 13 is downsized in the engine room. Furthermore, since the intercooler 13 can be reduced in size, the amount of heat dissipated in the intercooler 13 can be reduced, the temperature rise of the outside air can be suppressed, and the heat dissipation performance of the radiator 21 and the condenser 230 can be improved. As a result, the load of the engine 10 can be reduced.

  In addition, since the refrigerant flows in the order from the heater 211 to the heat exchanger 212, the temperature of the heat source with respect to the refrigerant can be increased in order, and a sufficient temperature difference between the refrigerant and each heat source is ensured. Thus, effective heat exchange, that is, heating of the refrigerant can be performed.

(Second Embodiment)
A second embodiment of the present invention is shown in FIG. 2nd Embodiment changes the arrangement | positioning position of the heater 211 and the heat exchanger 212 in the refrigerant | coolant flow direction of Rankine cycle 200 with respect to the said 1st Embodiment. Hereinafter, components different from those in the first embodiment in the present embodiment will be described.

  Here, a heat exchanger 212 is disposed on the refrigerant discharge side of the pump 240, and a heater 211 is disposed on the downstream side of the refrigerant flow of the heat exchanger 212. The refrigerant is pump 240 → heat exchanger 212 → heating. It circulates in the order of the vessel 211 → the expander 220 → the condenser 230.

  Immediately after the engine 10 is started, the engine coolant temperature is at a low level equal to or lower than a predetermined temperature, and the refrigerant cannot be heated by the heater 211. Rather, the engine 10 is in a state where it is desired to raise the temperature of the engine coolant early in order to reduce friction loss and the like.

  In the second embodiment, when the pump 240 is operated after the engine 10 is started, the refrigerant is heated by the heat exchanger 212 and then reaches the heater 211. In this heater 211, the temperature of the heated refrigerant becomes higher than the temperature of the engine cooling water, and the heater 211 acts as a radiator that releases the heat of the refrigerant to the engine cooling water. To heat positively.

  Thereby, early warm-up of the engine 10 using the Rankine cycle 200 can be aimed at, and a fuel consumption can be improved. In this case, since the sufficiently heated refrigerant cannot be supplied from the heater 211 to the expander 220, mechanical energy cannot be recovered as the Rankine cycle 200.

  Further, when the engine cooling water reaches a predetermined temperature or more due to the warm-up, the heater 211 performs the original heating function to heat the refrigerant, and as in the first embodiment, the expander By actuating 220, mechanical energy can be recovered by the Rankine cycle 200 (further power generation by a generator, etc.).

  At this time, the refrigerant is heated by the heater 211 after being heated by the heat exchanger 212, and the heat source temperature for the refrigerant is shifted from the higher side (intake air temperature) to the lower side (engine coolant temperature). become. Therefore, the refrigerant is suppressed at a level not exceeding the engine coolant temperature by the heater 211, becomes a superheated vapor refrigerant having a stable temperature, and is supplied to the expander 220. As a Rankine cycle 200, the mechanical is stable. Energy can be recovered.

(Third embodiment)
A third embodiment of the present invention is shown in FIGS. 3rd Embodiment enables it to switch the flow direction of the refrigerant | coolant between the pump 240 and the expander 220 with respect to the said 1st Embodiment. Hereinafter, components different from those in the first embodiment in the present embodiment will be described.

  Here, a four-way valve 250 is provided as a switching means for connecting between the pump 240 and the heater 211 and between the heat exchanger 212 and the expander 220. The four-way valve 250 is controlled by a control device (not shown) so as to open and close each flow path connected to the pump 240, the heater 211, the heat exchanger 212, and the expander 220. Specifically, the refrigerant flow is switched to either the first mode shown in FIG. 3 or the second mode shown in FIG. 4 by opening or closing each flow path of the four-way valve 250. In the first mode, the refrigerant flow (solid arrow in FIG. 3) is in the order of the pump 240 → the heater 211 → the heat exchanger 212 → the expander 220 → the condenser 230. In the second mode, the refrigerant flow ( The broken line arrows in FIG. 4 are arranged in the order of pump 240 → heat exchanger 212 → heater 211 → expander 220 → condenser 230.

  A control device (not shown) switches the refrigerant flow to the first mode by the four-way valve 250 when the engine coolant temperature becomes equal to or higher than a predetermined temperature after the engine 10 is started and the steady operation state is reached. In this case, the Rankine cycle 200 can be operated using the waste heat of the engine cooling water and the intake air effectively as in the first embodiment.

  Moreover, if it is immediately after starting of the engine 10, the control apparatus which is not illustrated switches a refrigerant | coolant flow to a 2nd mode with the four-way valve 250. FIG. In this case, it is possible to operate the Rankine cycle 200 that enables the engine 10 to be warmed up early as in the second embodiment.

  Thus, in 3rd Embodiment, it can be set as the waste-heat utilization apparatus 100 provided with the merit of both 1st Embodiment and 2nd Embodiment.

(Fourth embodiment)
A fourth embodiment of the present invention is shown in FIG. In the fifth embodiment, the intercooler 13 is eliminated from the first embodiment. Hereinafter, components different from those in the first embodiment in the present embodiment will be described.

  Here, as the heat exchange capability of the heat exchanger 212, the pressurized intake air temperature can be cooled to a predetermined cooling temperature. In the fourth embodiment, the Rankine cycle 200 is always operated by a control device (not shown) while the engine 10 is operated. The driving force obtained by the expander 220 is used for assisting the engine 10.

  As a result, the refrigerant in the Rankine cycle 200 can be heated by the heat exchanger 212 in addition to the heater 211. The pressurized intake air is always radiated to the refrigerant side by the heat exchanger 212, so that the intake air can be cooled to a predetermined cooling temperature. Usually, an intercooler (13 for cooling the intake air is set. ) Can be abolished.

(Fifth embodiment)
A fifth embodiment of the present invention is shown in FIG. The fifth embodiment is a waste heat utilization apparatus 100 provided with a refrigeration cycle 300 that shares the condenser 230 of the Rankine cycle 200 with respect to the first embodiment. Hereinafter, components different from those in the first embodiment in the present embodiment will be described.

  The refrigeration cycle 200 includes a compressor 310, the condenser 230, an expansion valve 320, and an evaporator 330, which are sequentially connected to form a closed circuit. The same refrigerant as in the Rankine cycle 200 is circulated in the refrigeration cycle 300. In the present embodiment, the HFC 134a is used as the refrigerant of the Rankine cycle 200 and the refrigeration cycle 300, similarly to the refrigerant of the Rankine cycle 200 in the first embodiment.

  The evaporator 330 is disposed in the air conditioning case 410 of the air conditioning unit 400, evaporates the refrigerant decompressed and expanded by the expansion valve 320, and cools the conditioned air sent from the blower by the latent heat of evaporation at that time. The heater core 31 in the heater core circuit 30 is also disposed in the air conditioning case 410, and heats the conditioned air blown by the blower by heat exchange with the engine cooling water, as in the first embodiment. Therefore, the mixing ratio of the conditioned air cooled by the evaporator 330 and the conditioned air heated by the heater core 31 is adjusted according to the opening of an air mix door (not shown) and adjusted to a temperature set by the occupant.

  As described above, in the waste heat utilization apparatus 100 including the Rankine cycle 200 and the refrigeration cycle 300, the refrigerant and the condenser 230 are shared, so that an inexpensive response can be achieved. Moreover, since only one condenser 230 is required for the two cycles 200 and 300, the mounting property on the vehicle can be improved.

  In this waste heat utilization apparatus 100, each cycle 200, 300 can be operated independently. That is, Rankine cycle independent operation, refrigeration cycle independent operation, and simultaneous operation of the refrigeration cycle and Rankine cycle are possible.

(Other embodiments)
In each of the above embodiments, the heat of the engine cooling water is used as the stable waste heat from the engine (internal combustion engine) 10. However, the present invention is not limited to this, and the heat of the exhaust gas may be used.

  Moreover, in each said embodiment, although the waste-heat utilization apparatus 100 of this invention was applied to the vehicle, application of this invention is not limited to this.

It is a schematic diagram which shows the whole structure of the waste-heat utilization apparatus in 1st Embodiment. It is a schematic diagram which shows the whole structure of the waste-heat utilization apparatus in 2nd Embodiment. It is a schematic diagram which shows the whole structure of the waste-heat utilization apparatus in 3rd Embodiment, and the refrigerant | coolant flow in 1st mode. It is a schematic diagram which shows the whole structure of the waste-heat utilization apparatus in 3rd Embodiment, and the refrigerant | coolant flow in 2nd mode. It is a schematic diagram which shows the whole structure of the waste-heat utilization apparatus in 4th Embodiment. It is a schematic diagram which shows the whole structure of the waste-heat utilization apparatus in 5th Embodiment.

Explanation of symbols

10 Engine (Internal combustion engine)
13 Intercooler 40 Supercharger 100 Waste heat utilization device 200 Rankine cycle 211 Heater (first heat exchanger)
212 Heat exchanger (second heat exchanger)
220 expander 230 condenser 250 four-way valve (switching means)
300 Refrigeration cycle

Claims (7)

The working fluid in the cycle is heated by the heat exchangers (211 and 212) by the waste heat related to the internal combustion engine (10), and the heated working fluid is expanded by the expander (220) to recover mechanical energy. In the waste heat utilization apparatus having the Rankine cycle (200) for condensing and liquefying the expanded working fluid in the condenser (230),
The internal combustion engine (10) includes a supercharger (40) that pressurizes intake air,
The heat exchangers (211 and 212) include a first heat exchanger (211) that heats the working fluid using stable waste heat from the internal combustion engine (10) as a heat source,
A waste heat utilization apparatus comprising: a second heat exchanger (212) that heats the working fluid using heat of the intake air pressurized by the supercharger (40) as a heat source.   The waste heat utilization apparatus according to claim 1, wherein the stable waste heat from the internal combustion engine (10) is heat of a coolant for cooling the internal combustion engine (10).   The waste heat utilization apparatus according to claim 2, wherein the second heat exchanger (212) is disposed on the upstream side of the working fluid flow of the first heat exchanger (211).   The switching means (250) for switching the flow order of the working fluid into the first heat exchanger (211) and the second heat exchanger (212) is provided. The waste heat utilization device described. During operation of the internal combustion engine (10), the Rankine cycle (200) is always operated,
The said 2nd heat exchanger (212) serves as the function of the intercooler (13) which cools the said pressurized said intake air, The Claim 1 characterized by the above-mentioned. Waste heat utilization equipment.   The refrigeration cycle (300) formed by sharing the condenser (230) with the Rankine cycle (200) and circulating the working fluid in the cycle is provided. Item 6. The waste heat utilization apparatus according to any one of Items 5.   The waste heat utilization apparatus according to any one of claims 1 to 6, wherein the internal combustion engine (10) is an engine (10) mounted on a vehicle.

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