JP2016145560A - Waste heat recovery device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a waste heat recovery device enabling improvement of waste heat recovery efficiency.SOLUTION: A waste heat recovery device 1 includes a Rankine cycle device 10 in which working fluid M is circulated. The Rankine cycle device 10 includes: an expansion device 14 into which the working fluid M is made to flow to output power; a gas liquid separator 15 provided downstream of the expansion device 14 to separate a gas phase and a liquid phase of the working fluid M from each other; and an ejector 13 provided upstream of the expansion device 14 to guide the gas phase of the working fluid M separated by the gas liquid separator 15 to the upstream side of the expansion device 14.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a waste heat recovery device, and more particularly to a waste heat recovery device including a Rankine cycle device.

  Conventionally, as a technique related to a waste heat recovery apparatus including a Rankine cycle apparatus, for example, a waste heat recovery apparatus described in Patent Document 1 is known. The waste heat recovery apparatus described in Patent Document 1 includes a Rankine cycle apparatus having an evaporator and an expander, and a gas-liquid separator provided between the evaporator and the expander. In this waste heat recovery apparatus, the liquid phase and the gas phase of the working fluid are separated by a gas-liquid separator, and the working fluid heading to the evaporator is heated using the heat of the liquid phase.

International publication WO2010 / 137360 pamphlet

  Here, as a recent waste heat recovery apparatus, for example, in order to reduce fuel consumption in an engine, an apparatus that can effectively use the energy of the working fluid flowing out from the expander and further improve the waste heat recovery efficiency is required. ing.

  This invention is made | formed in view of the said situation, and makes it a subject to provide the waste heat recovery apparatus which can improve waste heat recovery efficiency.

  A waste heat recovery apparatus according to the present invention is a waste heat recovery apparatus including a Rankine cycle device in which a working fluid is circulated, and the Rankine cycle device includes an expander that receives power and outputs power, and an expander The gas-liquid separator that separates the gas phase and the liquid phase of the working fluid is provided downstream of the expander, and the gas phase of the working fluid that is provided upstream of the expander and separated by the gas-liquid separator is disposed upstream of the expander. And an ejector for guiding.

  In this waste heat recovery apparatus, the gas phase of the working fluid flowing out from the expander is separated by the gas-liquid separator, guided to the upstream side of the expander by the ejector, and again flows into the expander. As a result, the flow rate of the working fluid in the expander can be increased, and the energy of the working fluid flowing out of the expander can be used effectively. Therefore, it is possible to improve the waste heat recovery efficiency.

  The Rankine cycle device may include a condenser that cools and condenses the working fluid, and the gas-liquid separator may be provided between the expander and the condenser. In this case, since the liquid phase of the working fluid separated by the gas-liquid separator flows into the condenser, the amount of heat released for condensation in the condenser is reduced. As a result, downsizing of the condenser is expected.

  The Rankine cycle apparatus may include an evaporator that heats and evaporates the working fluid, and the ejector may be formed integrally with the evaporator on the downstream side of the evaporator. When the evaporator and the ejector are separate, each of the downstream side of the evaporator and the ejector can be a pressure loss point of the working fluid, but if the ejector is integrally formed on the downstream side of the evaporator, the pressure Since loss points are reduced, the pressure loss of the working fluid can be suppressed.

  ADVANTAGE OF THE INVENTION According to this invention, the waste heat recovery apparatus which can improve waste heat recovery efficiency can be provided.

It is a schematic block diagram which shows the waste heat recovery apparatus which concerns on 1st Embodiment. It is a schematic block diagram which shows the waste heat recovery apparatus which concerns on 2nd Embodiment.

Hereinafter, preferred embodiments according to one aspect of the present invention will be described in detail with reference to the drawings. In the following description, the same or equivalent elements will be denoted by the same reference numerals, and redundant description will be omitted.
(First embodiment)

  FIG. 1 is a schematic block diagram showing a waste heat recovery apparatus according to the first embodiment. As shown in FIG. 1, the waste heat recovery apparatus 1 according to the first embodiment includes a Rankine cycle apparatus 10 and is mounted on a vehicle, for example. Examples of the vehicle to be applied include commercial vehicles such as trucks and buses. The vehicle is not particularly limited, and may be a large vehicle, a medium vehicle, a normal passenger vehicle, a small vehicle, a light vehicle, or the like.

  The Rankine cycle apparatus 10 receives, for example, waste heat of the engine 20 as heat input, converts thermal energy related to the waste heat into power, and outputs the power. The Rankine cycle apparatus 10 includes a working fluid pump 11, an evaporator 12, an expander 14, and a condenser 16 in the flow path 17. The flow path 17 of the Rankine cycle device 10 includes a first flow path 17 a to a seventh flow path 17 g, and the working fluid M is circulated through the flow path 17. Various fluids can be used as the working fluid M. Here, R134a which is a low boiling point medium is used.

  The working fluid pump 11 is a pump that feeds (pressurizes) the working fluid M and circulates it on the flow path 17. The working fluid pump 11 compresses the working fluid M and sends the working fluid M to the first flow channel 17 a on the downstream side of the flow channel 17.

  The evaporator 12 is a heat exchanger that is provided on the downstream side of the first flow path 17a and heats and evaporates the working fluid M compressed by the working fluid pump 11. In the evaporator 12, the cooling water W of the engine 20 is circulated. The evaporator 12 heats the working fluid M by the waste heat of the engine 20 that is input via the cooling water W. The evaporator 12 flows the evaporated working fluid M out to the second flow path 17 b on the downstream side of the flow path 17.

  The ejector 13 is provided on the downstream side of the second flow path 17 b and is provided on the upstream side of the expander 14. The ejector 13 includes a throttle portion 13a, a suction portion 13b, and an expansion portion 13c. The throttle portion 13 a is a nozzle-like member that is connected to the downstream side of the second flow path 17 b and tapers toward the downstream side of the flow path 17. The suction part 13b is disposed at the boundary between the throttle part 13a and the expansion part 13c, and connects the expansion part 13c and the gas-liquid separator 15 via the fifth flow path 17e. The inflating portion 13 c has a substantially conical shape that is widened toward the downstream side of the flow path 17. The expansion part 13c is connected to the upstream side of the third flow path 17c. The ejector 13 flows out the gas phase of the working fluid M evaporated by the evaporator 12 and the gas phase of the working fluid M guided from the gas-liquid separator 15 into the third flow path 17 c on the downstream side of the flow path 17. (Details will be described later).

  The expander 14 is provided on the downstream side of the third flow path 17c. The expander 14 is rotated by the inflowing working fluid M expanding, and outputs power. For example, a turbine or the like is used as the expander 14. The expander 14 may output a mechanical output, for example, and may be connected to a generator to output an electrical output, for example. The expander 14 flows the expanded working fluid M into the fourth flow path 17 d on the downstream side of the flow path 17.

  The gas-liquid separator 15 is provided downstream of the fourth flow path 17d (downstream of the expander 14), and the working fluid M that has flowed out of the expander 14 flows in. The gas-liquid separator 15 separates the gas phase and the liquid phase of the working fluid M that has flowed out of the expander 14. As the gas-liquid separator 15, for example, a centrifugal type in which the liquid phase of the working fluid M is separated by centrifugal force can be employed. The gas-liquid separator 15 flows the separated vapor phase of the working fluid M into the fifth flow path 17e. Moreover, the gas-liquid separator 15 is provided between the expander 14 and the condenser 16, and the separated liquid phase of the working fluid M flows out to the sixth flow path 17f.

  The condenser 16 is a heat exchanger that is provided on the downstream side of the sixth flow path 17f and cools and condenses (liquefies) the working fluid M. The condenser 16 is cooled by a low-temperature heat source (not shown). The low-temperature heat source includes, for example, a sub-radiator, and cools the condenser 16 with traveling wind when the vehicle travels. The condenser 16 flows the condensed working fluid M into the seventh flow path 17 g on the downstream side of the flow path 17.

  The engine 20 is an internal combustion engine such as a water-cooled diesel engine, for example, and includes an EGR cooler 21, a cooling water flow path 22, and a radiator 23. The EGR cooler 21 is a heat exchanger for cooling EGR [Exhaust Gas Recirculation] gas. The cooling water channel 22 is a channel through which the cooling water W of the engine 20 flows. In the cooling water flow path 22, for example, the cooling water W is circulated through the cylinder head of the engine 20 and the cylinder block to cool the engine 20, and the cooling water W is circulated through the EGR cooler 21 to cool the EGR cooler 21. Is done. The cooling water channel 22 is connected to the radiator 23. The radiator 23 cools the cooling water W that has cooled the engine 20 and the EGR cooler 21 by, for example, heat exchange with traveling wind.

  In the waste heat recovery apparatus 1 configured as described above, the ejector 13 uses the pressure drop of the working fluid M generated when the working fluid M from the evaporator 12 passes through the throttle portion 13a. The gas phase of the working fluid M separated by the separator 15 is guided upstream of the expander 14.

  Specifically, the working fluid M evaporated by the evaporator 12 (the gas phase of the working fluid M) flows into and passes through the throttle portion 13a. Since the working fluid M that has passed through the throttle portion 13a expands in the expansion portion 13c, the pressure of the working fluid M in the expansion portion 13c decreases. Therefore, the pressure of the working fluid M in the expansion portion 13c is lower than the pressure of the working fluid M on the gas-liquid separator 15 side (the fifth flow path 17e side). As a result, the gas phase of the working fluid M separated by the gas-liquid separator 15 is guided to the suction part 13b by the pressure difference via the fifth flow path 17e and introduced into the expansion part 13c of the ejector 13. .

  The working fluid M evaporated by the evaporator 12 and the gas phase of the working fluid M guided from the gas-liquid separator 15 by the ejector 13 flow into the expander 14. As a result, the flow rate of the working fluid M in the expander 14 is increased, and among the working fluid M that has flowed out of the expander 14, the gas phase having higher energy than the liquid phase flows into the expander 14 again.

  On the other hand, the liquid phase of the working fluid M separated by the gas-liquid separator 15 flows into the condenser 16. Specifically, since the gas-liquid separator 15 is provided between the expander 14 and the condenser 16, the condenser 16 receives from the vapor phase the working fluid M that has flowed out of the expander 14. However, the liquid phase with low energy flows in. As a result, the heat dissipation amount (necessary heat dissipation amount) related to the condensation in the condenser 16 is reduced, and the working fluid M in the condenser 16 is compared with the case where the gas phase and the liquid phase of the working fluid M are mixed. The heat capacity of the condenser 16 is increased and the heat exchange efficiency of the condenser 16 is improved.

  As described above, according to the waste heat recovery apparatus 1 according to the first embodiment, the working fluid M flowing out from the expander 14 is separated into a liquid phase and a gas phase by the gas-liquid separator 15. The separated gas phase of the working fluid M is guided upstream of the expander 14 by the ejector 13 and flows into the expander 14 again. Thereby, the flow volume of the working fluid M in the expander 14 can be increased, and the waste heat of the working fluid M flowing out from the expander 14 can be used as it is. Thus, the energy of the working fluid M flowing out from the expander 14 can be used effectively, and the waste heat recovery efficiency (system efficiency) can be improved.

The Rankine cycle apparatus 10 includes a condenser 16 that cools and condenses the working fluid M, and the gas-liquid separator 15 is provided between the expander 14 and the condenser 16. In this case, since the liquid phase of the working fluid M separated by the gas-liquid separator 15 flows into the condenser 16, the amount of heat release related to condensation is reduced in the condenser 16. As a result, downsizing of the condenser 16 is expected.
(Second Embodiment)

  Next, a second embodiment will be described. The waste heat recovery apparatus 1A according to the second embodiment is basically the same as the first embodiment except that the ejector 13 is formed integrally with the evaporator 12 on the downstream side of the evaporator 12. . In the following description, only matters different from the first embodiment will be described, and the same description as in the first embodiment will be omitted.

  FIG. 2 is a schematic block diagram showing a waste heat recovery apparatus according to the second embodiment. As shown in FIG. 2, the ejector 13 is formed integrally with the evaporator 12 on the downstream side of the evaporator 12. The ejector 13 includes a throttle portion 13d, a suction portion 13b, and an expansion portion 13c. The suction part 13b and the expansion part 13c are configured in the same manner as in the first embodiment.

  The throttling part 13d is a nozzle-like member that tapers toward the downstream side in the flow path 17, and is connected to the outlet part on the downstream side of the evaporator 12 without passing through the second flow path 17b. The throttle portion 13 d can be formed integrally with the evaporator 12 by forming, for example, an outlet portion on the downstream side of the evaporator 12 so as to taper toward the downstream side in the flow path 17.

  By the way, in general, when the evaporator 12 and the ejector 13 are provided separately, the evaporator 12 is throttled at the outlet portion on the downstream side of the evaporator 12 and is throttled by the throttle portion 13a of the ejector 13, that is, the evaporator 12 The cross-sectional area change occurs in the flow path 17 of the working fluid M on both the downstream side and the ejector 13. Therefore, the downstream side of the evaporator 12 and the throttle portion 13a of the ejector 13 can be a pressure loss portion where the pressure loss of the working fluid M is large. In this regard, in the second embodiment, since the ejector 13 is formed integrally with the evaporator 12 on the downstream side of the evaporator 12, the pressure loss portion where the cross-sectional area change occurs in the flow path 17 of the working fluid M is obtained. Can be collected in one place. Therefore, since the pressure loss location is reduced, the pressure loss of the working fluid M can be suppressed.

  As mentioned above, although preferred embodiment which concerns on this invention was described, this invention is not limited to the said embodiment, It deform | transforms in the range which does not change the summary described in each claim, or is applied to another thing. May be.

  For example, in the above embodiment, the diesel engine is used as an example of the engine 20, but an engine such as a gasoline engine may be used.

  Moreover, although the ejector 13 which has the aperture | diaphragm | squeeze part 13a (13d), the attraction | suction part 13b, and the expansion part 13c was illustrated, the ejector 13 is not limited to this. Various ejectors can be used as long as they are provided upstream of the expander 14 and guide the gas phase of the working fluid M separated by the gas-liquid separator 15 to the upstream of the expander 14.

  DESCRIPTION OF SYMBOLS 1,1A ... Waste heat recovery apparatus, 10 ... Rankine cycle apparatus, 12 ... Evaporator, 13 ... Ejector, 14 ... Expander, 15 ... Gas-liquid separator, 16 ... Condenser, M ... Working fluid.

Claims (3)

A waste heat recovery device including a Rankine cycle device in which a working fluid is circulated,
The Rankine cycle device is
An expander that receives the working fluid and outputs power;
A gas-liquid separator that is provided downstream of the expander and separates a gas phase and a liquid phase of the working fluid;
An exhaust heat recovery apparatus, comprising: an ejector provided upstream of the expander and guiding the gas phase of the working fluid separated by the gas-liquid separator to the upstream of the expander. The Rankine cycle device has a condenser that cools and condenses the working fluid,
The waste heat recovery apparatus according to claim 1, wherein the gas-liquid separator is provided between the expander and the condenser. The Rankine cycle device has an evaporator for heating and evaporating the working fluid,
The waste heat recovery apparatus according to claim 1 or 2, wherein the ejector is formed integrally with the evaporator on a downstream side of the evaporator.

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