JP5440336B2 - Engine waste heat recovery power generation method and apparatus - Google Patents

Description

  The present invention relates to an engine waste heat recovery power generation method and apparatus used for generating power by effectively using waste heat of an engine.

  An engine such as a vehicle converts heat energy generated by fuel combustion into kinetic energy, but its thermal efficiency (energy conversion efficiency) varies depending on the type of engine, but is at most 40 to 50%. Yes, most of the remaining heat energy that is not converted into work is released to the outside as heat (waste heat).

  Therefore, in order to improve the utilization efficiency of engine thermal energy, it has been considered to recover energy from engine waste heat (exhaust heat).

  As one method for recovering energy from the waste heat of this type of engine, for example, it is considered to recover the waste heat energy of the exhaust of the engine (for example, refer to Patent Document 1).

  By the way, in a water-cooled engine, coolant (coolant) is circulated through a coolant flow path (water jacket) provided at a required part of the engine, thereby cooling each part of the engine cylinder, head, etc. to overheat. The coolant that has been heated in connection with the cooling of the engine is guided to the radiator to indirectly exchange heat with the outside air, thereby transferring the heat held by the coolant to the atmosphere. In general, the coolant that has been dissipated and cooled by this heat dissipation is sent again to the cooling passage of the engine.

JP 2009-270522 A

  However, the one disclosed in Patent Document 1 is designed to recover the waste heat energy possessed by the exhaust gas. Normally, various devices for purifying the exhaust gas are provided in the exhaust gas flow path. Some devices for purifying exhaust gas of this type require temperature control, so the heat of the exhaust gas is efficiently recovered in the exhaust gas flow path. When a heat exchanger is provided, it is not sufficient to simply install a heat exchanger, and there is a problem that a significant design change is required for the flow path of the exhaust gas.

  Therefore, the present inventor pays attention to the heat possessed by the coolant in the heated state after being used for cooling the engine that is simply dissipated into the atmosphere by a radiator if it is a normal water-cooled engine. In order to increase the efficiency of use of the thermal energy of the engine and to store the generated electric power by effectively generating heat by using the heat held by the coolant after cooling the engine. The present invention has been made as a result of repeated efforts and research for suppressing the fluctuation of the charge / discharge power of the battery used in the above-mentioned process and extending the life and size of the battery.

  Therefore, an object of the present invention is to generate power by effectively using the heat held by the coolant after being used for cooling the engine in a water-cooled engine, and to store the generated power. It is an object of the present invention to provide an engine waste heat recovery power generation method and apparatus for suppressing fluctuations in the charge / discharge power of a battery used in the above-described method and extending the life and size of the battery.

  In order to solve the above problems, the present invention, corresponding to claim 1, is a working refrigerant that guides the coolant after cooling to the engine to the heat exchanger and supplies the coolant to the heat exchanger from the refrigerant pump. By exchanging heat, steam of the working refrigerant is generated in the heat exchanger, and a turbine connected to a generator is rotated by the steam of the working refrigerant generated in the heat exchanger to generate power by the generator. The power generated by the generator is stored in the battery, and the load power when the power stored in the battery is consumed by the load is equal to the power generation amount of the generator driven by the turbine. An engine waste heat recovery power generation method for adjusting the amount of working refrigerant supplied from the refrigerant pump to a heat exchanger that generates steam of the working refrigerant for driving the turbine; That.

  Corresponding to claim 2, a heat exchanger for exchanging heat between the coolant used for cooling the engine and the working refrigerant is connected to the coolant flow path of the engine, and the heat exchange is further performed. Connected to the refrigerant outlet and refrigerant inlet of the generator are a turbine connected to a generator, a condenser, and a refrigerant circulation line equipped with a refrigerant pump, and further connected to a battery for storing electric power generated by the generator. A load power measuring means for measuring the power consumption of the load and a controller for controlling the operation of the refrigerant pump in accordance with the power consumption of the load measured by the load power measuring means The engine waste heat recovery power generator with

  Further, in the above configuration, the controller drives the turbine connected to the generator from the refrigerant pump so that the power generation amount in the generator is equal to the power consumption of the load measured by the load power measuring means. And a function of adjusting the amount of the working refrigerant supplied to the heat exchanger that generates the working refrigerant vapor.

According to the present invention, the following excellent effects are exhibited.
(1) The coolant after being used for cooling the engine is guided to a heat exchanger, and heat exchange is performed with the working refrigerant supplied from the refrigerant pump to the heat exchanger. And generating a power by the generator by rotating the turbine connected to the generator by the steam of the working refrigerant generated by the heat exchanger, and storing the electric power generated by the generator in a battery. Furthermore, for driving the turbine from the refrigerant pump, the load power when the power stored in the battery is consumed by the load is equal to the power generation amount of the generator driven by the turbine. Since it is an engine waste heat recovery power generation method and device that adjusts the amount of working refrigerant supplied to the heat exchanger that generates the working refrigerant vapor, the cooling after the engine is cooled Thermal power can be generated by effectively utilizing the held runt.
(2) For a battery that stores the generated power, even if the power consumption of the load connected to the battery fluctuates, fluctuations in the charge / discharge power of the battery itself can be suppressed. In addition, since it is possible to reduce the frequency of use by reducing the repetition of charging and discharging of the battery, it is possible to extend the life of the battery.
(3) Further, by suppressing fluctuations in the charge / discharge power of the battery, it is not necessary to compensate for a large charge / discharge current in the battery, so that the size of the battery can be reduced.

1 is a schematic diagram showing an embodiment of an engine waste heat recovery power generation method and apparatus according to the present invention. It is a schematic diagram which shows transition of the charging / discharging electric power of the battery in the apparatus of FIG. It is a schematic diagram which shows transition of battery charging / discharging electric power when not performing operation control of the refrigerant pump based on the measured value of load electric power. It is a schematic diagram which shows the other form of implementation of this invention.

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  1 and 2 show an embodiment of an engine waste heat recovery power generation method and apparatus according to the present invention, which are as follows.

  That is, FIG. 1 shows an apparatus configuration of the engine waste heat recovery power generator according to the present invention. In the coolant-cooled flow path (not shown) of the water-cooled engine 1, coolant is supplied to the coolant inlet 2 and the coolant outlet 3. (Cooling liquid) Cooling the cooling liquid outlet 6b and the cooling liquid inlet 6a in the heat exchanger (evaporator) 6 for evaporating the working refrigerant 5 into vapor 5a by exchanging heat between the working refrigerant 5 and the working refrigerant 5. The liquid supply line 7 and the cooling liquid return line 8 are connected to each other.

  Further, a coolant pump (not shown) is provided on either the coolant inlet 2 portion, the coolant outlet 3 portion, the coolant supply line 7 or the coolant return line 8 of the engine 1. Thereby, the coolant 4 can be circulated and circulated between the coolant flow path of the engine 1 and the heat exchanger 6 by the operation of the coolant pump.

  Between the refrigerant outlet 6d of the working refrigerant 5 and the refrigerant inlet 6c in the heat exchanger 6, a turbine 10 in which a generator 11 is connected to a turbine shaft (not shown), a condenser 12, and a refrigerant pump 13 Are connected in order. Thereby, after the working refrigerant 5 discharged from the pump 13 is circulated through the refrigerant circulation line 9 to the heat exchanger 6, the turbine 10, and the condenser 12 in order by the operation of the refrigerant pump 13. The refrigerant pump 13 is returned to be circulated.

  The working refrigerant 5 is introduced into the heat exchanger 6 in a heated state after being circulated through the coolant flow path of the engine 1 and used for cooling the engine 1 during normal operation of the engine 1. A refrigerant having a boiling point lower than the temperature of the coolant 4, for example, a refrigerant having a boiling point lower than 100 ° C. is used.

  The condenser 12 is, for example, an air-cooled type, and when the working refrigerant vapor 5a is led from the turbine 10 side through the refrigerant circulation line 9, the working refrigerant vapor 5a is cooled and condensed to be a liquid working refrigerant. It can be set back to 5.

  Therefore, when the engine 1 is in operation, the coolant pump and the refrigerant pump 13 are both operated, so that the coolant 4 flows through the coolant flow path of the engine 1 and the coolant 4 The heated coolant 4 after cooling the engine 1 and being used for cooling the engine 1 is led to the heat exchanger 6 through the coolant return line 8, and the heat exchanger 6 operates as described above. Heat exchange with the refrigerant 5 is possible. Thereafter, the coolant 4 cooled by heat exchange with the working refrigerant 5 is supplied again to the coolant flow path of the engine 1 through the coolant supply line 7, whereby the heat of the engine 1 is continuously supplied by the coolant 4. So that it can be cooled.

  On the other hand, the working refrigerant 5 supplied to the heat exchanger 6 by the operation of the refrigerant pump 13 exchanges heat with the heated coolant 4 after being used for cooling the engine 1 in the heat exchanger 6. Once done, it will heat and evaporate. Therefore, the steam 5 a of the working refrigerant generated in the heat exchanger 6 is guided to the turbine 10 through the refrigerant circulation line 9, so that the turbine 10 is rotationally driven. The generator 11 can be driven to generate power.

  The working refrigerant vapor 5a after being used for rotational driving of the turbine 10 as described above is led to the condenser 12 through the refrigerant circulation line 9, cooled, condensed, and returned to the liquid working refrigerant 5. After that, the refrigerant pump 13 can be returned to the suction side.

  A battery 14 for storing electric power generated by the generator 11 is connected to the generator 11. Furthermore, a load 15 such as a required power device is connected to the battery 14 via an energization cable 16.

  Furthermore, in the engine waste heat recovery power generator of the present invention, as means for suppressing fluctuations in the charge / discharge power of the battery 14, the energizing cable 16 connecting the battery 14 and the load 15 is provided in the middle. A power meter 17 as a load power (load power consumption) measuring means is provided at the position, and an operation control command is given to the refrigerant pump 13 based on a load power measurement signal input from the power meter 17. It is assumed that the controller 18 is provided.

  More specifically, the controller 18 rotationally drives the turbine 10 that is rotationally driven by the flow rate of the working refrigerant 5 supplied to the heat exchanger 6 and the steam 5 a of the working refrigerant generated in the heat exchanger 6. It is assumed that data on the correlation with the power generation amount of the generator 11 driven by the above is accumulated in advance.

  In addition, when the load power measurement value is input from the power meter 17, the controller 18 causes the power generation amount in the generator 11 to be equal to the load power measurement value input from the power meter 17. The flow rate of the working refrigerant 5 to the heat exchanger 6 required for the heat exchanger 6, the flow rate of the working refrigerant 5 supplied to the heat exchanger 6 stored in the controller 18, and the power generation amount in the generator 11, And a function of giving a control command for operating the refrigerant pump 13 to the refrigerant pump 13 so that the obtained flow rate is achieved.

  When the operation of the refrigerant pump 13 is controlled by the controller 18, if the flow rate of the working refrigerant 5 supplied from the refrigerant pump 13 to the heat exchanger 6 is reduced, the heat exchanger 6 causes the engine 1 to be reduced. Since the amount of the working refrigerant 5 for exchanging heat with the coolant 4 after being cooled is reduced, the temperature of the coolant 4 that is circulated and supplied to the coolant flow path of the engine 1 is sufficiently cooled. It is thought that it will disappear.

  For this purpose, in the engine waste heat recovery power generator according to the present invention, a branch coolant return line 19 is provided at a position in the middle of the coolant return line 8, and a radiator is provided downstream of the branch coolant return line 19. 20 is connected to the outlet side of the radiator 20 through a coolant line 21 to the middle of the coolant supply line 7. Further, the coolant line in the coolant supply line 7 is connected to the outlet side of the radiator 20. A thermostat 22 for adjusting the flow rate of the coolant 4 that flows into the coolant supply line 7 from the coolant line 21 is provided at the connection portion 21. Thereby, the temperature of the coolant 4 supplied from the heat exchanger 6 to the coolant flow path of the engine 1 through the coolant supply line 7 is higher than a certain set temperature desired for the coolant 4 supplied to the engine 1. Is higher, the amount of the coolant 4 that flows into the coolant supply line 7 from the coolant line 21 by the operation of the thermostat 22, that is, the coolant 4 flows through the coolant return line 8 after being used for cooling the engine 1. Of the coolant 4, the coolant 4 is led from the middle position of the coolant return line 8 through the branch coolant return line 19 to the radiator 20, cooled by the radiator 20, and then guided to the coolant line 21. By increasing the temperature of the coolant 4 supplied to the engine 1 from the coolant supply line 7, the temperature of the radiator 20 is increased. The amount of coolant 4 to cool are to be adjusted by.

  Reference numeral 23 denotes a manual valve provided on the upstream side of the coolant supply line 7 in the coolant supply line 7, and the coolant flowing through the heat exchanger 6 is adjusted by adjusting the throttle amount of the manual valve 23. The amount of 4 and the amount of coolant 4 through which the radiator 20 is circulated can be manually adjusted.

  When power is generated by the engine waste heat recovery power generator of the present invention having the above-described configuration, the engine 1 is operated, and when the coolant pump and the refrigerant pump 13 are both operated, the engine 1 is cooled. In the heat exchanger 6 to which the heated coolant 4 is guided through the coolant return line 8, the waste heat of the engine 1 that is the heat held by the coolant 4 and the heat from the coolant pump 13 through the coolant circulation line 9. Heat exchange of the working refrigerant 5 supplied to the exchanger 6 is performed, and the working refrigerant 5 is evaporated by this heat exchange, and a vapor 5a of the working refrigerant is generated.

  When the liquid working refrigerant 5 evaporates and the working refrigerant vapor 5a is generated as described above, the volume expands and the pressure increases. Therefore, the working refrigerant vapor 5a whose pressure has increased. Is guided to the turbine 10 through the refrigerant circulation line 9, and the generator 11 generates power as the turbine 10 is driven to rotate.

  The electric power generated by the generator 11 is temporarily stored in the battery 14 connected to the generator 11, and then supplied to the load 15 via the energizing cable 16 and consumed by the load as necessary. Will come to be.

  At this time, when load power is measured by the wattmeter 17 provided on the energizing cable 16, a control command is given to the refrigerant pump 13 by the controller 18 based on the measured value, and the refrigerant pump 13, the flow rate when supplying the working refrigerant 5 to the heat exchanger 6 is required to make the power generation amount in the generator 11 equal to the measured value of the load power input from the wattmeter 17. The flow rate is adjusted.

  Here, as a comparison, considering the case where the refrigerant pump 13 is not operated according to the load power as described above, in this case, the amount of heat generated in the engine 1 is substantially constant in the steady operation state of the engine 1. Therefore, heat is exchanged between the heated coolant 4 after the cooling of the engine 1 and the heat exchanger 6 and the coolant 4 is cooled to a set temperature desired for supplying the coolant 4 to the engine 1. For this purpose, the working refrigerant 5 may be supplied from the refrigerant pump 13 to the heat exchanger at a constant flow rate.

  Therefore, since the flow rate of the working refrigerant vapor 5a supplied from the heat exchanger 6 to the turbine 10 is substantially constant, the electric power [W] generated by the generator 11 is represented by a line D in FIG. Furthermore, the value is substantially constant with respect to the elapsed time [s].

  However, in this case, as shown by a line E in FIG. 3, when the load power fluctuates, the charge / discharge power of the battery 14 shown by the line F in FIG. 3 fluctuates according to the load fluctuation. Therefore, since the battery 14 is repeatedly charged and discharged according to the fluctuation of the load power, the frequency of use of the battery 14 increases and the life of the battery 14 decreases. Furthermore, since it becomes necessary to compensate the battery 14 for a sufficient charge / discharge current, the size of the battery 14 increases.

  Therefore, in the engine waste heat recovery power generator according to the present invention, when the load power fluctuates as shown by line B in FIG. 2, the operation of the refrigerant pump 13 is controlled according to the fluctuation, and the heat exchanger By controlling the flow rate of the working refrigerant 5 supplied to 6, the power generation amount of the generator 11 driven by the turbine 10 is such that the load power (line B in FIG. 2) as shown by the line A in FIG. 2. It is designed to be controlled equally. As a result, in the battery 14 that supplies power to the load 15 and stores the power generated by the generator 11, as shown by line C in FIG. Become.

  As described above, according to the engine waste heat recovery power generation method and apparatus of the present invention, it is possible to generate power by effectively using the heat held by the coolant 4 after cooling the engine 1. Moreover, in the battery 14 configured to store the generated power, even when the power consumption (load power) of the load 15 connected to the battery 14 fluctuates, the charging / discharging of the battery 14 itself is performed. Electric power fluctuation can be suppressed. Therefore, since the repetition of charging / discharging of the battery 14 can be reduced and the use frequency of the battery 14 can be reduced, the life of the battery 14 can be extended. Furthermore, since it is not necessary to compensate for a large charge / discharge current in the battery 14 as the fluctuation of the charge / discharge power of the battery 14 is suppressed, the size of the battery 14 can be reduced.

  In the above-described embodiment, the configuration in which the wattmeter 17 is provided in the middle of the energization cable 16 that connects the battery 14 and the load 15 as the load power measuring means has been shown. It is good also as a provided structure. In this case, based on the fact that the voltage of the battery 14 is substantially constant, the controller 18 loads the product of the measured value of the supply current to the load 15 measured by the ammeter and the voltage of the battery 14. The processing for obtaining the power consumed in 15 may be performed.

  Furthermore, as shown in FIG. 4, the load power measuring means may be configured by a resistor 24 provided at an intermediate position of the energizing cable 16 and a voltmeter 25 connected in parallel to the resistor 24. The resistor 24 may be a resistor having a known small resistance value. Other configurations are the same as those shown in FIG. 1, and the same components are denoted by the same reference numerals.

  In the case of such a configuration, the controller 18 calculates the supply current to the load 15 based on the known resistance value of the resistor 24 and the voltage measurement value by the voltmeter 25, and this calculation is performed. A process for obtaining the power consumed by the load 15 by the product of the obtained current value and the voltage of the battery 14 may be performed.

  The present invention is not limited to the above-described embodiment, and may be applied to an engine 1 other than the vehicle as long as it is a water-cooled engine 1.

  Of course, various modifications can be made without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Engine 4 Coolant 5 Working refrigerant 5a Steam of working refrigerant 6 Heat exchanger 6d Refrigerant outlet 6c Refrigerant inlet 9 Refrigerant circulation line 10 Turbine 11 Generator 12 Condenser 13 Refrigerant pump 14 Battery 15 Load 17 Wattmeter (Load power measuring means)
18 Controller 24 Resistance (Load power measuring means)
25 Voltmeter (load power measurement means)

Claims (3)

  The coolant after being used for cooling the engine is led to a heat exchanger, and heat exchange is performed with the working refrigerant supplied to the heat exchanger from a refrigerant pump, thereby generating steam of the working refrigerant in the heat exchanger, The turbine connected to the generator is rotated by steam of the working refrigerant generated in the heat exchanger, the power is generated by the generator, and the electric power generated by the generator is stored in the battery. The refrigerant pump supplies the working refrigerant for driving the turbine so that the load power when the power stored in the battery is consumed by the load is equal to the power generation amount of the generator driven by the turbine. An engine waste heat recovery power generation method characterized by adjusting the amount of working refrigerant supplied to a heat exchanger that generates steam.   A heat exchanger for exchanging heat between the coolant used for cooling the engine and the working refrigerant is connected to the coolant flow path of the engine, and power generation is performed at the refrigerant outlet and the refrigerant inlet of the heat exchanger. For measuring the power consumption of a load connected to a battery connected to a turbine for connecting a turbine, a condenser, and a refrigerant circulation line including a refrigerant pump, and further storing electric power generated by the generator. Engine waste heat comprising: a load power measuring means; and a controller for controlling the operation of the refrigerant pump in accordance with the power consumption of the load measured by the load power measuring means Recovery power generator.   The controller uses a refrigerant pump to drive the turbine connected to the generator from the refrigerant pump so that the power generation amount in the generator is equal to the power consumption of the load measured by the load power measuring means. The engine waste heat recovery power generator according to claim 2, which has a function of adjusting the amount of working refrigerant supplied to a heat exchanger that generates heat.

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