JP2014190216A - Waste heat regeneration system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to detect leakage of refrigerant at an early stage if a water-heat exchanger on a Rankine cycle circuit fails and the refrigerant leaks to a cooling water circuit, and to remove the refrigerant from the cooling water circuit.SOLUTION: A waste heat regeneration system 100 includes: a Rankine cycle circuit 10 that includes a cooling water boiler 3 and in which refrigerant circulates; a first water circuit 31 connected to the cooling water boiler 3, and for causing water circulating inside to exchange heat with the refrigerant in the cooling water boiler 3; and operating fluid removing means 13 that includes a chlorofluorocarbon detector 13a for detecting presence of the refrigerant in the first water circuit 31 and a relief valve 13b for discharging the refrigerant to an outside of the first water circuit 31.

Description

  The present invention relates to a waste heat regeneration system, and more particularly to a waste heat regeneration system that uses waste heat of a vehicle engine using a Rankine cycle.

  Waste heat regeneration systems for vehicles using Rankine cycle circuits that recover mechanical energy (power) from engine waste heat have been developed. A general Rankine cycle circuit includes a pump that pumps a refrigerant such as chlorofluorocarbon as a working fluid, a boiler that heats the refrigerant by exchanging heat with waste heat of the engine, and expands the heated refrigerant to generate mechanical energy. An expander to be recovered and a condenser that cools and condenses the expanded refrigerant are connected and sequentially connected to form a closed circuit.

  The boiler provided in the Rankine cycle circuit of Patent Literature 1 is connected to a cooling water circuit for engine cooling, and performs heat exchange between the cooling water in the cooling water circuit and the refrigerant in the Rankine cycle circuit. A device that exchanges heat between the cooling water in the cooling water circuit and the refrigerant in the Rankine cycle circuit like this boiler is referred to as a water heat exchanger. When such a water heat exchanger fails and the connection between the coolant circuit and the Rankine cycle circuit communicates, the pressure in the Rankine cycle circuit is higher than that of the coolant circuit. There is a possibility of leakage to the circuit side. And when a refrigerant | coolant mixed in the cooling water of a cooling water circuit, cavitation generate | occur | produced in the water pump of a cooling water circuit, and there existed a possibility of causing the failure of the apparatus on a cooling water circuit.

  Here, Patent Document 2 describes a configuration in which the pressure of air in the water tank on the cooling water circuit is detected, and when the air pressure becomes high, the pressure valve is opened to release the air to the outside. ing.

JP 2012-67687 A Utility Model Public Notice No. 3-20491

  In the cooling water circuit of the waste heat regeneration system as described in Patent Document 1, in order to detect the leakage of the refrigerant from the Rankine cycle circuit and remove the refrigerant, the cooling water circuit as in Patent Document 2 is used. A method of degassing by detecting the pressure of the gas at the bottom can be considered. That is, in the method described in Patent Document 2, the gas is discharged outside after the detected gas pressure exceeds a certain value. However, when the hole opened at the junction between the coolant circuit and the Rankine cycle circuit is small, the refrigerant gradually enters the coolant circuit side over time. Therefore, it takes time until the pressure reaches a certain value, and the leakage of the refrigerant cannot be detected immediately.

  In order to solve such problems, the present invention detects the leakage of the working fluid at an early stage when the water heat exchanger on the Rankine cycle circuit breaks down and the working fluid leaks to the cooling water circuit side. An object of the present invention is to provide a waste heat regeneration system capable of removing a working fluid from a water circuit.

In order to solve the above problems, a waste heat regeneration system according to the present invention includes a water circuit through which water flows, and a Rankine cycle circuit that has a water heat exchanger and through which a working fluid flows. Connected to the heat exchanger and exchanges heat with the Rankine cycle circuit, working fluid detection means for detecting the presence of the working fluid in the water circuit, and based on the detection of the presence of the working fluid by the working fluid detection means Working fluid discharge means for discharging the fluid to the outside of the water circuit.
As a result, even before the pressure in the water circuit rises to a certain value, the working fluid detection means detects the presence of the working fluid that has entered the water circuit, and the working fluid is discharged to the outside of the water circuit. Can be discharged.

The water circuit of the waste heat regeneration system according to the present invention may include a water circuit pump, and the working fluid detection means and the working fluid discharge means may be provided downstream of the water heat exchanger and upstream of the water circuit pump.
In addition, the working fluid detection unit and the working fluid discharge unit may be arranged on the top side in the top-to-bottom direction with respect to the region where water exists in the water circuit.

In addition, a gas-liquid separation tank is provided on the water circuit of the waste heat regeneration system according to the present invention, and the working fluid detection means and the working fluid discharge means are located within the gas-liquid separation tank more than the area where water exists. It may be arranged on the top side of the direction.
In addition, the water circuit protrudes into the gas-liquid separation tank and flows into the gas-liquid separation tank, and the water circuit protrudes into the gas-liquid separation tank and separates the water in the water circuit from gas to liquid. And an upper end of the outflow end portion may be located below the upper end of the inflow end portion.

  Moreover, the water circuit of the waste heat regeneration system according to the present invention includes a radiator that cools water flowing through the water circuit, and the radiator replenishes the radiator with water or discharges unnecessary water in the radiator. The working fluid detection means and the working fluid discharge means may discharge the refrigerant in the water circuit to the overflow path.

  According to the waste heat regeneration system according to the present invention, when the water heat exchanger on the Rankine cycle circuit fails and the working fluid leaks to the cooling water circuit side, the leakage of the working fluid is detected at an early stage to detect the cooling water. The working fluid can be removed from the circuit.

It is a schematic diagram which shows the structure of the waste heat regeneration system which concerns on Embodiment 1 of this invention. It is a schematic diagram which shows the structure of the working fluid removal means on the cooling water circuit in the waste heat regeneration system shown in FIG. It is a schematic diagram which shows the structure of the waste heat regeneration system which concerns on Embodiment 2 of this invention. It is a schematic diagram which shows the structure of the working fluid removal means on the cooling water circuit in the waste heat regeneration system shown in FIG. It is a schematic diagram which shows the relationship between the cooling water circuit and reservoir tank in the waste heat regeneration system which concerns on Embodiment 3 of this invention. It is a schematic diagram which shows the structure of the working fluid removal means on the cooling water circuit in the waste heat regeneration system shown in FIG. It is a schematic diagram which shows the structure of the waste-heat regeneration system which concerns on Embodiment 4 of this invention.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
A waste heat regeneration system 100 according to Embodiment 1 of the present invention will be described with reference to FIGS.
FIG. 1 shows an overall configuration of the waste heat regeneration system 100.
The waste heat regeneration system 100 includes a pump 2, a cooling water boiler 3, an exhaust gas boiler 4, an expander 6, and a condenser 8, which are sequentially connected to form a Rankine cycle circuit 10 that is a closed circuit. To do. In the Rankine cycle circuit 10, a refrigerant as a working fluid is circulated. The pump 2 is connected to the motor 5.
Here, the cooling water boiler 3 comprises a water heat exchanger. In the present embodiment, chlorofluorocarbon is used as the refrigerant.

  The pump 2 is driven by the motor 5 and pumps the refrigerant in the Rankine cycle circuit 10 in the waste heat regeneration system 100. Further, the cooling water boiler 3 heats and evaporates the refrigerant with the waste heat of the cooling water that has cooled the engine 20, and the exhaust gas boiler 4 with the waste heat of the exhaust gas of the engine 20. The expander 6 expands the refrigerant vaporized in the cooling water boiler 3 and the exhaust gas boiler 4 to generate mechanical energy. Here, the expander 6 has an expander side drive shaft 26, and the engine 20 has an engine side drive shaft 21. A belt 22 is attached between the expander side drive shaft 26 and the engine side drive shaft 21. The mechanical energy generated in the expander 6 assists the engine 20 via the expander side drive shaft 26, the belt 22, and the engine side drive shaft 21. Further, the condenser 8 cools and condenses the vaporized refrigerant to liquefy it.

  A first water circuit 31 is connected to the cooling water boiler 3. The first water circuit 31 is configured by sequentially connecting a cooling water boiler 3, a first radiator 34, and a water circuit pump 32. Here, the first radiator 34 is for cooling the refrigerant flowing through the first water circuit 31. Further, a working fluid removing means 13 described later is provided downstream of the cooling water boiler 3 and upstream of the first radiator 34, that is, downstream of the cooling water boiler 3 and upstream of the water circuit pump 32. The first water circuit 31 passes through the engine 20 downstream of the water circuit pump 32 and upstream of the cooling water boiler 3. The cooling water pumped by the water circuit pump 32 receives the waste heat of the engine 20 to cool the engine 20. The cooling water heated by the waste heat of the engine 20 exchanges heat with the refrigerant in the Rankine cycle circuit 10 in the cooling water boiler 3. Next, the cooling water is cooled by the first radiator 34 and then pumped to the engine 20 by the water circuit pump 32 again.

  An exhaust pipe 41 is connected to the exhaust gas boiler 4. High-temperature exhaust gas discharged from the engine 20 circulates in the exhaust pipe 41, and heat is exchanged with the refrigerant flowing through the Rankine cycle circuit 10 in the exhaust gas boiler 4 to heat the refrigerant.

Next, the configuration of the working fluid removing means 13 will be described with reference to FIG. In the following description, the upward direction in the vertical direction is the top side X in the vertical direction.
The working fluid removing means 13 includes a Freon detector 13a and a relief valve 13b. The Freon detector 13a is a semiconductor sensor, and is attached to the top side X in the top-and-bottom direction relative to the region where the cooling water of the first water circuit 31 exists. Further, an opening 39 is formed adjacent to the chlorofluorocarbon detector 13a on the top side X from the region where the cooling water of the first water circuit 31 exists. The relief valve 13 b is attached to the opening 39. The Freon detector 13a and the relief valve 13b are electrically connected.
Here, the chlorofluorocarbon detector 13a constitutes a working fluid detection means, and the relief valve 13b constitutes a working fluid discharge means.

  When the coolant boiler 3 fails and the refrigerant in the Rankine cycle circuit 10 leaks into the first water circuit 31, the Freon detector 13a of the working fluid removing means 13 detects the presence of the refrigerant. The CFC detector 13a that has detected the presence of the refrigerant sends a detection signal to the relief valve 13b. The relief valve 13b that has received the detection signal is opened, and the refrigerant is discharged to the outside of the first water circuit 31 through the opening 39.

  As described above, in the waste heat regeneration system 100 according to the first embodiment, by providing the first water circuit 31 with the Freon detector 13a and the relief valve 13b, the first water circuit 31 due to the failure of the cooling water boiler 3 is provided. The refrigerant leakage can be detected at an early stage, and the refrigerant can be removed. That is, when refrigerant leakage is detected by pressure as in the prior art, refrigerant cannot be detected unless the gas pressure in the first water circuit 31 exceeds a certain value, but if the CFC detector 13a is used, the first water circuit 31 is used. It is possible to immediately detect the presence of chlorofluorocarbon as a refrigerant before the pressure increases. When the relief valve 13b of the opening 39 is opened by the detection signal from the Freon detector 13a, the refrigerant is released to the atmosphere outside the first water circuit 31 through the opening 39. Therefore, the refrigerant can be removed from the water circuit 31 before the refrigerant enters the water circuit pump 32 and cavitation occurs.

Further, by providing the working fluid removing means 13 downstream of the cooling water boiler 3 and upstream of the water circuit pump 32, the refrigerant that has entered from the failed cooling water boiler 3 can be removed before entering the water circuit pump 32. . Therefore, the occurrence of cavitation in the water circuit pump 32 can be prevented.
Furthermore, since the vaporized refrigerant is accumulated above the first water circuit 31, by disposing the working fluid removing means 13 on the top side X in the vertical direction from the region where the cooling water exists in the first water circuit 31, The refrigerant can be removed more reliably.

Embodiment 2. FIG.
A waste heat regeneration system 200 according to Embodiment 2 of the present invention will be described with reference to FIGS.
The overall configuration of the waste heat regeneration system 200 is shown in FIG. In the waste heat regeneration system 100, the waste heat regeneration system 200 is gas-liquid separated downstream of the cooling water boiler 3 on the first water circuit 31 and upstream of the first radiator 34, that is, downstream of the cooling water boiler 3 and upstream of the pump 2. A tank 38 is provided. A working fluid removing means 23 is provided inside the gas-liquid separation tank 38.
Since the same reference numerals as those in FIG. 1 are the same or similar components, detailed description thereof is omitted.

The configurations of the gas-liquid separation tank 38 and the working fluid removing means 23 will be described with reference to FIG.
The gas-liquid separation tank 38 has a substantially cylindrical shape, and the cooling water and the refrigerant that has entered the first water circuit 31 are stored therein. Here, the CFC detector 23a is attached to the upper side in the gas-liquid separation tank 38, that is, the top side X in the top-and-bottom direction from the region where the cooling water exists. Further, an opening 38a is formed adjacent to the Freon detector 23a on the top side X in the vertical direction from the region where the cooling water in the gas-liquid separation tank 38 exists. The relief valve 23b is attached to the opening 38a. The Freon detector 23a and the relief valve 23b are electrically connected.
Here, the working fluid removing means 23 includes a Freon detector 23a and a relief valve 23b. Further, the CFC detector 23a constitutes a working fluid detection means, and the relief valve 23b constitutes a working fluid discharge means. The CFC detector 23a is a semiconductor sensor.

  Inside the gas-liquid separation tank 38, the inflow end portion 31 a and the outflow end portion 31 b of the first water circuit 31 protrude toward the top side X in the vertical direction through the bottom portion 38 b. The upper end 31ba of the outflow end 31b is positioned below the upper end 31aa of the inflow end 31a. Further, in a normal state in which cooling water is accumulated in the gas-liquid separation tank 38, if the portion above the coolant surface is the upper portion 38c and the lower portion is the lower portion 38d, the upper end 31aa of the inflow end portion 31a is In the upper part 38c, the upper end 31ba of the outflow end part 31b is located in the lower part 38d. The cooling water flowing through the first water circuit 31 flows into the gas-liquid separation tank 38 from the inflow end portion 31a and flows out of the gas-liquid separation tank 38 from the outflow end portion 31b.

  When the cooling water boiler 3 breaks down and the refrigerant in the Rankine cycle circuit 10 enters the first water circuit 31, the flon detector 23 a detects the presence of the refrigerant that has entered the gas-liquid separation tank 38. The chlorofluorocarbon detector 23a that has detected the refrigerant sends a detection signal to the relief valve 23b to open the relief valve 23b.

As described above, in the waste heat regeneration system 200 according to this embodiment, the gas-liquid separation tank 38 is provided on the first water circuit 31, so that the gas containing the refrigerant in the gas-liquid separation tank 38 is in the upper portion 38c. In addition, the cooling water is separated into the lower portion 38d. Therefore, even when the cooling water boiler 3 is broken down by the working fluid removing means disposed on the top side X in the vertical direction from the region where the cooling water in the gas-liquid separation tank 38 exists, the inside of the first water circuit 31 can be more reliably The refrigerant can be removed.
Further, since the upper end 31ba of the outflow end 31b of the first water circuit 31 is located in the lower part 38d of the gas-liquid separation tank 38, the upper end 31ba of the outflow end 31b is usually located below the water surface of the cooling water. . Therefore, only the cooling water flows out from the outflow end portion 31b to the outside of the gas-liquid separation tank 38, and the refrigerant does not enter the first water circuit 31 again through the outflow end portion 31b. Therefore, it is possible to more reliably prevent the refrigerant from entering the water circuit pump 32 and the occurrence of cavitation.

Embodiment 3 FIG.
A waste heat regeneration system 300 according to Embodiment 3 of the present invention will be described with reference to FIGS.
FIG. 5 shows the relationship between the first water circuit 31 and the reservoir tank 36.
In the waste heat regeneration system 300, the reservoir tank pipe line 35 connected to the reservoir tank 36 and the first water circuit 31 are connected via the communication path 51. The communication passage 51 is connected to the first water circuit 31 at a position downstream of the first radiator 34 on the first water circuit 31 and upstream of the water circuit pump 32, that is, downstream of the cooling water boiler 3 and upstream of the water circuit pump 32. It is. Furthermore, a working fluid removing means 33 is provided at a position where the first water circuit 31 and the communication path 51 are connected.
Since the same reference numerals as those in FIG. 1 are the same or similar components, detailed description thereof is omitted.

The reservoir tank 36 is connected to the first radiator 34 via a reservoir tank conduit 35. Cooling water flows through the reservoir tank pipe 35, and the flowing direction of the cooling water is changed according to the pressure inside the first radiator 34. That is, when the pressure inside the first radiator 34 is high, the cooling water overflows and flows out from the first radiator 34, and unnecessary cooling water is discharged to the reservoir tank 36 via the reservoir tank pipe 35. On the other hand, when the pressure inside the first radiator 34 is low, the cooling water stored in the reservoir tank 36 is supplied to the first radiator 34 via the reservoir tank conduit 35. A drain pipe 37 is attached to the reservoir tank 36. When the cooling water stored in the reservoir tank 36 exceeds a certain amount, it is discharged to the outside through the drain pipe 37.
The reservoir tank conduit 35 and the reservoir tank 36 constitute an overflow path.

The configuration of the working fluid removing means 33 will be described with reference to FIG.
The working fluid removing means 33 is composed of a Freon detector 33a and a relief valve 33b, like the working fluid removing means 13 shown in FIG. The Freon detector 33a is attached to the top side X in the vertical direction from the region where the cooling water in the first water circuit 31 exists. Further, the communication path 51 is branched from the area of the first water circuit 31 where the cooling water exists to the top side X adjacent to the Freon detector 33a. The relief valve 33 b is provided on the communication path 51 at a position close to the first water circuit 31. Further, the Freon detector 33a and the relief valve 33b are electrically connected. The CFC detector 33a is a semiconductor sensor.
Here, the CFC detector 33a constitutes a working fluid detection means, and the relief valve 33b constitutes a working fluid discharge means.

  When the cooling water boiler 3 breaks down and the refrigerant in the Rankine cycle circuit 10 leaks into the first water circuit 31, the CFC detector 33a of the working fluid removing means 33 detects the presence of the refrigerant and sends the detection signal to the communication path 51. It sends to the upper relief valve 33b. The relief valve 33 b that has received the detection signal is in an open state, and the first water circuit 31 and the reservoir tank conduit 35 are in communication with each other via the communication passage 51. Then, the refrigerant in the first water circuit 31 is discharged to the reservoir tank pipe 35 through the communication path 51.

  As described above, in the waste heat regeneration system 300 according to this embodiment, the first water circuit 31 and the reservoir tank pipe 35 are connected via the communication path 51, and the relief valve 33 b is provided on the communication path 51. It has been. Thus, even when the infiltrated refrigerant is removed from the first water circuit 31 and the cooling water is also discharged from the communication path 51, the cooling water remains in the reservoir tank pipe 35 and the reservoir tank 36. It can be prevented from leaking outside the device. Further, since the cooling water discharged to the reservoir tank conduit 35 and the reservoir tank 36 flows into the first water circuit 31 again via the first radiator 34, the water can be effectively used. The refrigerant discharged to the reservoir tank conduit 35 and the reservoir tank 36 is discharged to the outside through the drain pipe 37.

  The working fluid removing means 33 is not limited to the one shown in FIG. 6 and is installed inside the gas-liquid separation tank provided on the second water circuit 61 in the same manner as the working fluid removing means 23 shown in FIG. CFC detectors and relief valves may be used.

Embodiment 4 FIG.
A waste heat regeneration system 400 according to Embodiment 4 of the present invention will be described with reference to FIG. FIG. 7 shows the overall configuration of the waste heat regeneration system 400.
In the waste heat regeneration system 400, the capacitor 8 is connected to the second water circuit 61 in the waste heat regeneration system 100 according to the first embodiment. The second water circuit 61 is a circuit through which cooling water for cooling the intercooler 66 that cools the intake air compressed by the turbocharger (not shown) flows. The second water circuit 61 is configured by sequentially connecting a second water circuit pump 62, a capacitor 8, an intercooler 66, and a second radiator 64. The second radiator 64 is for cooling the refrigerant flowing through the first water circuit 31. A working fluid removing means 63 is provided downstream of the condenser 8 and upstream of the intercooler 66, that is, downstream of the condenser 8 and upstream of the second water circuit pump 62. The working fluid removing means 63 is composed of a Freon detector and a relief valve, like the working fluid removing means 13 shown in FIG. However, the present invention is not limited to this, and the working fluid removal means 63 is, as in the working fluid removal means 23 described in FIG. 4, a freon detection attached inside the gas-liquid separation tank provided on the second water circuit 61. And a relief valve.

  As described above, in the waste heat regeneration system 400 according to this embodiment, even if the condenser 8 fails, as in the waste heat regeneration systems 100, 200, 300 of the first to third embodiments, the second water The refrigerant that has entered the circuit 61 can be removed early. As a result, it is possible to prevent the refrigerant from entering the second water circuit pump 62 and the occurrence of cavitation.

  In the first to third embodiments, the water heat exchanger connected to the water circuit is only the cooling water boiler 3, and in the fourth embodiment, the cooling water boiler 3 and the condenser 8 are water heat exchangers. However, the condenser 8 alone may be provided as a water heat exchanger.

In the first to fourth embodiments, a semiconductor sensor is used for the chlorofluorocarbon detector. However, the present invention is not limited to this, and an infrared optical sensor or the like may be used.
Moreover, the refrigerant | coolant which distribute | circulates the Rankine cycle circuit 10 is not limited to Freon, Ethanol may be sufficient, and a working fluid detection means may be an ethanol detector instead of a Freon detector.

  100, 200, 300, 400 Waste heat regeneration system, 3 Cooling water boiler (water heat exchanger), 8 condenser (water heat exchanger), 10 Rankine cycle circuit, 13, 23, 33, 63 Working fluid removing means, 13a , 23a, 33a Freon detector (working fluid detection means), 13b, 23b, 33b Relief valve (working fluid discharge means), 20 engine, 31 first water circuit (water circuit), 31a inflow end, 31aa inflow end 31b, outflow end, 31ba, upper end of outflow end, 32, 62 water circuit pump, 38 gas-liquid separation tank, X upside down.

Claims (6)

A water circuit through which water flows, and a Rankine cycle circuit having a water heat exchanger and through which a working fluid flows, wherein the water circuit is connected to the water heat exchanger and exchanges heat with the Rankine cycle circuit. A waste heat regeneration system to perform,
Working fluid detection means for detecting the presence of the working fluid in the water circuit;
A waste heat regeneration system comprising: a working fluid discharge unit that discharges the working fluid to the outside of the water circuit based on detection of the presence of the working fluid by the working fluid detection unit. The water circuit comprises a water circuit pump;
The waste heat regeneration system according to claim 1, wherein the working fluid detection means and the working fluid discharge means are provided downstream of the water heat exchanger and upstream of the water circuit pump.   3. The waste heat regeneration system according to claim 1, wherein the working fluid detection unit and the working fluid discharge unit are disposed on the top side in the top-and-bottom direction of the water circuit in the water circuit. A gas-liquid separation tank is provided on the water circuit,
3. The waste heat regeneration system according to claim 1, wherein the working fluid detection unit and the working fluid discharge unit are arranged on the top side in the top-to-bottom direction with respect to a region where water exists in the gas-liquid separation tank. The water circuit is
An inflow end that protrudes into the gas-liquid separation tank and allows water in the water circuit to flow into the gas-liquid separation tank;
An outflow end that protrudes into the gas-liquid separation tank and causes water in the water circuit to flow out of the gas-liquid separation tank;
Have
The waste heat regeneration system according to claim 4, wherein an upper end of the outflow end is positioned below an upper end of the inflow end. The water circuit includes a radiator that cools water flowing through the water circuit,
The radiator includes an overflow path for supplying water to the radiator or discharging unnecessary water in the radiator,
The waste heat regeneration system according to any one of claims 1 to 5, wherein the working fluid detection unit and the working fluid discharge unit discharge the refrigerant in the water circuit to the overflow path.

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