KR101477741B1 - Exhaust heat recovery device from engine - Google Patents

Abstract

And a condenser for condensing the refrigerant discharged from the compressor and supplying the refrigerant to the compressor, wherein the compressor, the compressor, the condenser, the evaporator, (Hereinafter, referred to as a " first refrigerant ") flowing out of the first compressor, and a second refrigerant discharged from the first compressor, the refrigerant flowing out of the first compressor, the refrigerant flowing out of the first compressor, (Hereinafter, referred to as " second refrigerant ") before being introduced into the condenser, heat-exchanges the refrigerant with each other, and discharges the refrigerant; An engine waste heat recovering device including an exhaust pipe;

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine waste heat recovery apparatus, and more particularly, to an engine waste heat recovery apparatus capable of improving waste heat recovery rate by using heat of engine cooling water and exhaust gas discharged from an engine for heat exchange.

As energy depletion and environmental problems arise, various types of exhaust heat recovery apparatuses have been developed in order to recycle the heat contained in the exhaust gas discharged from the engine of the vehicle.

BACKGROUND ART [0002] Conventional exhaust emission heat recovery apparatuses for vehicles are disclosed in, for example, Korean Patent Laid-Open Publication No. 10-2011-0062015, in which waste heat contained in exhaust gas discharged to the outside of a vehicle is supplied to engine cooling water, engine oil or transmission oil And recover heat through heat exchange to improve the heating performance and fuel efficiency of the vehicle.

KR 10-2011-0062015 A

According to an embodiment of the present invention, it is possible to provide an engine waste heat recovery apparatus capable of increasing the recovery rate of waste heat by increasing the temperature of the refrigerant by using remaining heat even after heat exchange between the engine cooling water and the waste heat of the exhaust gas.

According to an embodiment of the present invention, there is provided a compressor comprising: a compressor for compressing and discharging a refrigerant; an expander for flowing refrigerant flowing out of the compressor to discharge refrigerant; a condenser for condensing the refrigerant discharged from the compressor; 1. An engine waste heat recovery apparatus for recovering heat contained in exhaust gas and cooling water discharged from an engine using a refrigerant circulating through the compressor, the inflator, and the condenser, the apparatus comprising: a condenser; (Hereinafter, referred to as a 'first refrigerant') and a refrigerant before being introduced into the condenser (hereinafter referred to as a 'second refrigerant'), exchanges heat with each other, and discharges the refrigerant; An engine waste heat recovering device may be provided.

The engine waste heat recovering apparatus according to an embodiment of the present invention is characterized in that the second refrigerant before being introduced into the first regenerative heat exchanger and the first refrigerant discharged from the first regenerative heat exchanger are introduced into the second regenerative heat exchanger, And a regenerating heat exchanger.

The engine waste heat recovery apparatus according to an embodiment of the present invention further includes a first heat exchanger for introducing the first refrigerant discharged from the first regenerative heat exchanger and the cooling water discharged from the engine to heat exchange with each other, And the first refrigerant into which the second regenerative heat exchanger is introduced may be the first refrigerant discharged from the first heat exchanger.

The engine waste heat recovery apparatus according to an embodiment of the present invention may further include a second heat exchanger for introducing the first refrigerant discharged from the first heat exchanger and the exhaust gas discharged from the engine, .

The engine waste heat recovery apparatus according to an embodiment of the present invention includes a first heat exchanger for exchanging heat between the first refrigerant discharged from the second heat exchanger and the exhaust gas before being introduced into the second heat exchanger, And the exhaust gas into which the second heat exchanger has been introduced may be the exhaust gas discharged from the third heat exchanger.

An engine waste heat recovery apparatus according to an embodiment of the present invention includes an exhaust gas recirculation device for recirculating a portion of exhaust gas discharged from the second heat exchanger to the exhaust gas recirculation device Wherein the second heat exchanger is configured to receive the reprocessed exhaust gas supplied from the exhaust gas recirculation device and to exchange the refilled exhaust gas with the first refrigerant flowing in from the first heat exchanger Exchanged and discharged, and the reprocessed exhaust gas discharged by the second heat exchanger may be provided to the engine.

The engine waste heat recovery apparatus according to an embodiment of the present invention includes a first refrigerant discharged from the second heat exchanger and an exhaust gas discharged from the engine before being introduced into the second heat exchanger, And a third heat exchanger.

The first heat exchanger may further take in atmospheric air from the turbocharger and heat-exchange the atmospheric air and the first refrigerant discharged from the first regenerative heat exchanger with each other.

The apparatus for recovering waste heat according to an embodiment of the present invention may further include a second inflator for introducing the exhaust gas discharged from the second heat exchanger to cause the turbocharger to work.

Wherein the first regenerative heat exchanger exchanges heat with the refrigerant flowing in from the compressor through the atmospheric air discharged from the second heat exchanger.

According to the embodiment of the present invention, since the evaporation temperature of the refrigerant by the first heat exchanger is slightly lower than the engine cooling water, even if the refrigerant is preheated in the first regenerative heat exchanger, the first heat exchanger can utilize the engine cooling water heat as 100% .

Further, by utilizing the engine cooling water heat as the evaporation heat at the maximum of 100%, the engine waste heat recovery apparatus can reduce the temperature difference between the heat source and the working fluid in the process of evaporating the refrigerant in the first heat exchanger, It is possible to reduce the irreversible loss caused by the temperature difference in the evaporation process.

Further, according to the embodiment of the present invention, as the ratio of the high-temperature exhaust gas heat to the low-temperature engine coolant water ratio varies according to the condition of the engine, both of them can be utilized for heat exchange by maximally utilizing 100%.

1 is a view showing a first waste heat recovering apparatus according to an embodiment of the present invention,
2 is a graph showing an ORC Ts diagram related to engine waste heat recovery in the first waste heat recovery apparatus described with reference to FIG. 1,
3 is a graph showing an ORC Ts diagram related to the recovery of engine waste heat in the first waste heat recovery apparatus when the refrigerant flow rate is the optimum flow rate,
4 is a graph showing an ORC Ts diagram related to the recovery of engine waste heat in the first waste heat recovery apparatus when the refrigerant flow rate is less than the optimum flow rate,
5 is a graph showing an ORC Ts diagram related to the recovery of engine waste heat in the first waste heat recovery apparatus when the refrigerant flow rate is larger than the optimum flow rate,
6 to 8 are graphs for explaining the case where the optimum flow rate of the coolant is varied according to the ratio of the heat of the engine coolant to the heat of the exhaust gas,
9 is a view showing a second waste heat recovering apparatus according to another embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The above and other objects, features, and advantages of the present invention will become more readily apparent from the following description of preferred embodiments with reference to the accompanying drawings. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments disclosed herein are provided so that the disclosure can be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

In this specification, when an element is referred to as being on another element, it may be directly formed on another element, or a third element may be interposed therebetween. Further, in the drawings, the thickness of the components is exaggerated for an effective description of the technical content.

Where the terms first, second, etc. are used herein to describe components, these components should not be limited by such terms. These terms have only been used to distinguish one component from another. The embodiments described and exemplified herein also include their complementary embodiments.

The expression that component A and component B are connected (or connected or fastened or coupled) to each other in the description and / or claims of the present application means that component A and component B are directly connected or that one or more of the other components Quot; is used in the meaning including to be connected by an intermediary.

Also, terms used herein are for the purpose of illustrating embodiments and are not intended to limit the invention. In the present specification, the singular form includes plural forms unless otherwise specified in the specification. The terms "comprises" and / or "comprising" used in the specification do not exclude the presence or addition of one or more other elements.

Hereinafter, the present invention will be described in detail with reference to the drawings. In describing the specific embodiments below, various specific details have been set forth in order to explain the invention in greater detail and to assist in understanding it. However, it will be appreciated by those skilled in the art that the present invention may be understood by those skilled in the art without departing from such specific details. In some instances, it should be noted that portions of the invention that are not commonly known in the description of the invention and are not significantly related to the invention do not describe confusing reasons for explaining the present invention.

FIG. 1 is a view showing a first waste heat recovering apparatus according to an embodiment of the present invention, and FIG. 2 is a graph showing an ORC Ts diagram related to an engine waste heat recovery in the first waste heat recovering apparatus described with reference to FIG. In the ORC Ts diagram of FIG. 2, P _H represents the temperature and entropy of the refrigerant under high pressure, and P _L represents the temperature and entropy of the refrigerant at low pressure.

1 and 2, the waste heat recovery when the refrigerant for the waste heat recovery apparatus in FIG. 1 is located at a point indicated by "1" (a point between the first condenser 25 and the first compressor 11) The temperature of the refrigerant for the apparatus is indicated by '1' on the ORC Ts diagram of FIG. 2 to FIG. 7, respectively. 1, the temperature of the refrigerant for the waste heat recovery apparatus when the refrigerant for the waste heat recovery apparatus is located at the point indicated by "2" (the point between the first compressor 11 and the first regenerative heat exchanger 19) Quot; 2 " on the ORC Ts diagrams of Figs. 2 to 7. Similarly, in FIG. 1, the refrigerant for the waste heat recovery apparatus is located at a point indicated by '3', '4', '5', '6', '7', '8' The temperature at the time when the temperature was measured was indicated as '3', '4', '5', '6', '7', '8', and '9' on the ORC Ts diagrams of FIGS.

1, a refrigerant (1) refers to a refrigerant at a point indicated by reference numeral 1 in FIG. 1, and when referring to a refrigerant (2) The refrigerant 4, the refrigerant 5, the refrigerant 6, the refrigerant 7, and the refrigerant 6 in a similar manner to the refrigerant 3, 3 ',' 4 ',' 5 ',' 6 ',' 7 ',' 8 ', and' 9 'in FIG. 1 when referring to the refrigerant 8 and the refrigerant 9, Means a refrigerant when it is located at one point.

1, the first waste heat recovering apparatus includes a first compressor 11, a first heat exchanger 13, a second heat exchanger 15, a third heat exchanger 17, a first regenerative heat exchanger 19 ), A second regenerative heat exchanger (21), a first inflator (23), and a first condenser (25). On the other hand, the engine 27 is additionally shown in Fig. 1 for the purpose of describing the first waste heat recovering apparatus.

In operation of the engine 27, exhaust gas of high temperature is discharged from the engine 27. In order to reduce or eliminate the heat generated during operation of the engine 27, low-temperature cooling water flows into the engine 27, absorbs heat generated from the engine 27, and flows out as high-temperature cooling water.

The first regenerative heat exchanger 19, the first heat exchanger 13, the second heat exchanger 15, the second regenerative heat exchanger 21, and the second regenerative heat exchanger 21. In the first waste heat recovering apparatus, The third heat exchanger 17 and the first inflator 23 and the refrigerant flowing out of the first inflator 23 flows into the first compressor 11 again and is circulated.

The refrigerant for the waste heat recovery apparatus is circulated in the first waste heat recovering apparatus to recover the heat contained in the exhaust gas discharged from the engine 27 and the heat contained in the cooling water flowing out to the engine 27, The heat recovery efficiency is maximized by performing heat exchange between the refrigerants.

In the present specification, the cooling water flowing into the engine 27 for the purpose of the present invention is referred to as "engine cooling water" or "cooling water", and the refrigerant circulated in the first waste heat recovery apparatus is referred to as " Refrigerant "or simply" refrigerant ".

On the other hand, for the purpose of the description of the present invention, the refrigerant for the waste heat recovery apparatus may be referred to as " first refrigerant " or " second refrigerant " For example, in the present specification, a refrigerant for a waste heat recovery apparatus is referred to as a " first refrigerant " when it is located at a point indicated by 1, 2, 3, 4, 5, , Or when it is located at the point marked 9, it is called "second refrigerant".

The first compressor (11) receives the first refrigerant (1) flowing out from the first condenser (15), compresses it, and discharges it to the first regeneration heat exchanger (19) side.

The first refrigerant 2 discharged from the first compressor 11 and the second refrigerant 8 discharged from the second regenerative heat exchanger 21 flow into the first regenerative heat exchanger 19. Here, the first regenerative heat exchanger (19) is configured to perform heat exchange between the first refrigerant (2) and the second refrigerant (8) into which it flows.

The second refrigerant (8) discharged from the second regenerative heat exchanger (21) contains residual heat.

Referring to FIG. 2, the temperature of the second refrigerant 8 discharged from the second regenerative heat exchanger 21 is the position indicated by "8" in the ORC Ts diagram, and flows into the first regenerative heat exchanger 19 Since the temperature of the first refrigerant 2 before the first regenerative heat exchanger 19 is at the position indicated by "2" in the ORC Ts diagram, heat exchange is performed between the first refrigerant and the second refrigerant introduced into the first regenerative heat exchanger 19, The residual heat of the second refrigerant having a higher temperature is transferred to the first refrigerant.

Referring to FIG. 2, in the first regenerative heat exchanger 19, the first refrigerant is supplied with the heat amount Q _R1 from the second refrigerant. As a result, the temperature of the first refrigerant 3 discharged from the first regenerative heat exchanger 19 becomes higher than the temperature of the first refrigerant 2 before entering the first regenerative heat exchanger 19, The temperature of the second refrigerant 9 discharged from the first regenerative heat exchanger 19 becomes lower than the temperature of the second refrigerant 8 before entering the first regenerative heat exchanger 19.

The first heat exchanger 13 receives the high temperature engine cooling water discharged to the engine 27 and the preheated first refrigerant 3 discharged from the first regenerative heat exchanger 19. In the first heat exchanger (13), heat exchange is performed between the high temperature engine cooling water and the preheated first refrigerant.

2, since the temperature of the first refrigerant 3 discharged from the first regenerative heat exchanger 19 is the position indicated by "3" in the ORC Ts diagram, in the first heat exchanger 13, (3), the heat of the engine cooling water having a higher temperature is transferred to the first refrigerant.

Referring to FIG. 2, in the first heat exchanger 13, the first refrigerant is supplied with the heat quantity Q _H1 from the engine-use cooling water. The temperature of the engine cooling water discharged from the first heat exchanger 13 is lower than the temperature of the engine cooling water injected into the first heat exchanger 13 and the temperature of the first refrigerant discharged from the first heat exchanger 13 Becomes higher than the temperature of the first refrigerant (3) before it flows into the first heat exchanger (13).

The optimum flow rate of the first refrigerant used for the heat exchange with the engine cooling water is determined by the heat recovery amount Q _H1 of the engine cooling water, the first refrigerant 2 discharged from the first compressor 11 and the first refrigerant discharged from the first heat exchanger 13 (H4-h2) between the first refrigerant 4 and the heat amount Q _R1 recovered by the first regenerative heat exchanger 19 can be determined. This will be described later with reference to FIG. 2 and [Equation 1].

The engine cooling water discharged from the first heat exchanger 13 is supplied to the engine 27 again and the first refrigerant 4 discharged from the first heat exchanger 13 is supplied to the second heat exchanger 15 and the second regenerator And then flows into the heat exchanger (21). Here, the second heat exchanger (15) is configured to perform heat exchange between the first refrigerant and the exhaust gas, and the second regenerative heat exchanger (21) performs heat exchange between the first refrigerant and the second refrigerant .

In the second heat exchanger (15), heat exchange occurs between the exhaust gas discharged from the first refrigerant (4) discharged from the first heat exchanger (13) and the third heat exchanger (17).

2, since the temperature of the first refrigerant 4 discharged from the first heat exchanger 13 is the position indicated by "4" in the ORC Ts diagram, the second refrigerant in the second heat exchanger 15 4) Heat of the exhaust gas having a higher temperature is transferred to the first refrigerant.

Referring to FIG. 2, in the second heat exchanger 15, the first refrigerant is supplied with the heat amount Q _H2 from the exhaust gas, whereby the temperature of the first refrigerant 5 is higher than the temperature of the first refrigerant 4 While the temperature of the exhaust gas is lower than before the exhaust gas is introduced into the second heat exchanger 15. The exhaust gas whose temperature has been lowered by the heat exchange in the second heat exchanger 15 can be discharged from the engine 27 or can be re-supplied to the engine 27 after being reprocessed in a re-supplyable state. This will be described later with reference to FIG.

The third heat exchanger 17 performs heat exchange between the exhaust gas discharged from the engine 27 and the first refrigerant 5 discharged from the second heat exchanger 15 or the second regenerative heat exchanger 21. Here, the third heat exchanger (17) is configured to perform heat exchange between the first refrigerant and the exhaust gas.

Referring to FIG. 2, since the temperature of the first refrigerant 5 is the position indicated by '5' in the ORC T-s diagram, the heat of the exhaust gas is transferred to the first refrigerant in the third heat exchanger 17.

Referring to FIG. 2, in the third heat exchanger 17, the first refrigerant 5 is supplied with the heat quantity Q _H3 from the exhaust gas. As a result, the temperature of the first refrigerant 6 discharged from the third heat exchanger 17 becomes higher than the temperature of the first refrigerant 5, while the temperature of the exhaust gas discharged from the third heat exchanger 17 becomes Is lower than before it is injected into the third heat exchanger (17).

The flow rate of the second refrigerant used for the heat exchange with the exhaust gas is determined by the heat recovery amount QH3 of exhaust gas, the first refrigerant 4 discharged from the first heat exchanger 13 and the second refrigerant discharged from the third heat exchanger 17 (H6-h4) between the first refrigerant (6) and the heat amount (QR2) recovered by the second regenerative heat exchanger (21). This will be described later with reference to FIG. 2 and [Equation 2].

The exhaust gas whose temperature is lowered in the third heat exchanger 17 flows into the second heat exchanger 15 and the first refrigerant 6 whose temperature is increased flows into the first expander 23.

The first refrigerant 6 whose temperature has been raised by the third heat exchanger 17 performs work _equivalent to W _E in the first inflator 23 and then flows into the second regenerative heat exchanger 21.

In the second regenerative heat exchanger (21), heat exchange is performed between the first refrigerant (4) discharged from the first heat exchanger (13) and the second refrigerant (7). 2, the first refrigerant 4 and the second refrigerant 7 are introduced into the second regenerative heat exchanger 21 and the first refrigerant 4 in the second regenerative heat exchanger 21 flows into the second regenerative heat exchanger 21, And receives the heat amount Q _R2 from the refrigerant 7.

The second refrigerant (8) whose temperature is lowered in the second regenerative heat exchanger (21) flows into the first regenerative heat exchanger (19).

2, the temperature of the second refrigerant 8 is still higher than that of the first refrigerant 2, and thus the heat of the second refrigerant 8 in the second regenerative heat exchanger 21 is supplied to the first refrigerant 8, (2). The first refrigerant is preheated to some extent in the second regenerative heat exchanger 21 and then flows into the third heat exchanger 17 described above.

The second refrigerant 8 flows through the second regenerative heat exchanger 21 and flows into the first condenser 25 after the temperature drops so that the energy required to cool the second refrigerant 9 in the first condenser 25 Can be reduced.

The first condenser 25 condenses the lowered second refrigerant 9 in the first regenerative heat exchanger 19 to further lower the temperature of the second refrigerant 9. [ The first refrigerant (1) whose temperature has been lowered by condensation is supplied to the first compressor (11). The second refrigerant 8 flowing into the first condenser 25 is lowered in temperature by the second regenerative heat exchanger 21 and the first regenerative heat exchanger 19 and is supplied to the first regenerative heat exchanger 19, A part of the residual heat is used. Thus, the first condenser 25 can condense the second refrigerant 9 with less cooling capacity than before the first regenerative heat exchanger 19 is provided.

The first refrigerant 1 condensed in the first condenser 25 is compressed by the first compressor 11 and then supplied to the first regenerative heat exchanger 19, the first heat exchanger 13, the second regenerative heat exchange The refrigerant is circulated to the first heat exchanger 21, the second heat exchanger 15, the third heat exchanger 17, the first inflator 23, the second regenerative heat exchanger 21 and the first regenerative heat exchanger 19 .

According to the first waste heat recovering apparatus described with reference to Fig. 1, the heat of the engine cooling water can be utilized by providing the low-temperature first regenerative heat exchanger 19 and the high-temperature second regenerative heat exchanger 21. [ That is, it is possible to maximize the heat recovery from the same waste heat source by maximizing utilization of the remaining heat of the refrigerant and the heat of the engine cooling water after the refrigerant is expanded in the first inflator 23.

Specifically, the first refrigerant (3) in the liquid state preheated by the low-temperature first regenerative heat exchanger (19) is evaporated by the high temperature of the engine coolant in the first heat exchanger (13) Is superheated by the heat exchanger 21 and is superheated to the maximum temperature in the second heat exchanger 15 and the third heat exchanger 17 by the heat of the exhaust gas of the engine 27 to be supplied to the first inflator 23, .

According to the present embodiment, the evaporation temperature of the refrigerant in the liquid state by the first heat exchanger 13 is slightly lower than the engine cooling water, and is disposed between the first regenerative heat exchanger 19 and the second regenerative heat exchanger 21 Even if the first refrigerant 2 in the liquid state is preheated by the first regenerative heat exchanger 19 and then flows into the first heat exchanger 13, the first refrigerant 2 flowing into the first heat exchanger 13 Can utilize 100% of the heat contained in the engine cooling water as evaporation heat.

In this way, the first waste heat recovering device can reduce the temperature difference between the heat source and the working fluid during the evaporation of the first refrigerant (2). Therefore, the temperature difference in the process of evaporation due to heat contained in the existing engine exhaust gas Lt; RTI ID = 0.0 > irreversible < / RTI >

Also, the ratio of the high-temperature exhaust gas heat and the low-temperature engine coolant water ratio may be different depending on the conditions of the engine 27. Even in this case, the first waste heat recoverer can utilize both the exhaust gas heat and the engine coolant water heat up to 100% The heat recovery from the same waste heat source can be maximized.

Meanwhile, the ORC T-s diagram shown in FIG. 3 is a graph showing a case where the refrigerant flow rate is the optimum flow rate at which the heat recovery is maximized. Hereinafter, the process of calculating the optimum refrigerant flow rate will be described.

The control characteristics for constructing the line as shown in FIG. 3 are as follows. P _H , P _L, and T max, from which the maximum efficiency of the cycle can be obtained, are determined by the following control characteristics.

First, the high pressure (P _H ) condition of the refrigerant improves the cycle efficiency as the pressure increases, but in the embodiment of the present invention, the high pressure condition is determined by the boiling point of the refrigerant, and the temperature of the refrigerant is set to be lower than the temperature of the engine cooling water .

Second, the higher the maximum heating temperature Tmax of the refrigerant at the upstream side of the first inflator 23 is, the higher the cycle efficiency is. However, the maximum heating temperature Tmax of the refrigerant is limited by the maximum operating temperature in consideration of the thermal stability of the refrigerant .

Third, the low pressure (P _L ) condition of the refrigerant improves the cycle efficiency as the pressure is lower, but in the embodiment of the present invention, the low pressure condition is determined by the condensation temperature of the refrigerant, and is determined according to the given condensation environment.

Considering the above three conditions, in order to utilize the heat of the engine cooling water and the heat of the exhaust gas at the same time at maximum 100% under a given engine condition, for example, the optimum refrigerant flow rate can be determined by the following relation.

In Equation (1), Q _H1 is the heat recovery amount of the engine cooling water recovered in the first heat exchanger (13), and m _dot is the optimum amount of the first refrigerant used for heat exchange with the engine cooling water H2 is the enthalpy of the first refrigerant 2 discharged from the first compressor 11, h4 is the enthalpy of the first refrigerant 4 discharged from the first heat exchanger 13, and (h4-h2) 1 is the enthalpy increase amount between the refrigerant 2 and the first refrigerant 4 and Q _R1 is the amount of heat recovered from the second refrigerant 8 by the first regenerative heat exchanger 19.

In Equation (2), Q _H3 is the heat recovery amount of the exhaust gas recovered in the third heat exchanger 17, and m _dot is the optimum amount of the first refrigerant used for heat exchange with the exhaust gas in the optimum refrigerant flow amount used for heat exchange. H4 is the enthalpy of the first refrigerant 4 discharged from the first heat exchanger 13, h6 is the enthalpy of the first refrigerant 6 discharged from the third heat exchanger 17, (h6-h4) The enthalpy increase amount between the first refrigerant 6 and the first refrigerant 4 and Q _R2 is the amount of heat recovered from the second refrigerant 7 by the second regenerative heat exchanger 21.

A first waste heat recovery apparatus according to an embodiment of the present invention, Equation 1 and determines the optimum coolant flow rates (m _dot) by a relational expression of Equation (2), the determined m _dot is on the Ts diagram of Figure 2 4 points. The graph shown in Fig. 2 shows a diagram when the refrigerant flow rate used is set to the optimum flow rate.

At the same time, the rotational speed of the first inflator 23 can also be controlled and determined optimally for the refrigerant conditions (P _H and T max) and the refrigerant flow rate (m _dot ) at the front end of the first inflator 23.

4 is a graph showing an ORC T-s diagram related to the recovery of engine waste heat in the first waste heat recovery apparatus when the refrigerant flow rate is less than the optimum flow rate.

In FIG. 4, 'OPT' means the optimum refrigerant flow rate.

Referring to FIG. 4, when the flow rate of the first refrigerant 2 is less than the optimum flow rate obtained by Equations (1) and (2) The position of the refrigerant 4 moves to the right in comparison with FIG. Even if the flow rate of the refrigerant is small, the '3' point heated through the first regenerative heat exchanger 19 is the same, but when the flow rate of the refrigerant becomes small, the '4' point heated by the same engine coolant water flows to the right Because it moves.

Accordingly, the refrigerant flow rate (m _dot ) decreases in (2) and the amount of increase in enthalpy from the point '4' to the point '6' decreases, _H3 ) is decreased and the ORC output is also reduced accordingly.

5 is a graph showing an ORC T-s diagram related to the recovery of engine waste heat in the first waste heat recovery apparatus when the refrigerant flow rate is greater than the optimum flow rate.

In FIG. 5, 'OPT' means the optimum refrigerant flow rate.

Referring to FIG. 5, when the flow rate of the first refrigerant 2 is greater than the optimum flow rate obtained by the equations (1) and (2), on the contrary, 1, the position of the refrigerant 4 moves to the left in comparison with FIG. Therefore, the recovery heat quantity Q _{H3 of the} exhaust gas heat of the engine can be maximized in the equation (2), but (h6-h4) decreases as the refrigerant flow rate m _dot increases, (I.e., the maximum temperature before the first inflator 23) is lower than Tmax in Fig. This temperature reduction causes the cycle efficiency to decrease and thus the ORC output to the same input calorie is reduced.

6 to 8 are graphs for explaining a case where the optimum flow rate of the coolant varies according to the ratio of the heat of the engine coolant to the heat of the exhaust gas.

6 is a graph showing the optimum flow rate of the refrigerant when the heat of the engine coolant and the heat of the exhaust gas are the same.

Referring to FIG. 6, the ratio of the heat of the engine coolant and the heat of the exhaust gas, which discharge the heat, is changed according to the condition of the engine 27. According to an embodiment of the present invention, the first waste heat recovering apparatus can _reduce the refrigerant flow rate at the point "4" to the reference flow rate (that is, the optimum flow rate) when the heat of the engine cooling water Q _H1 and the heat of the exhaust gas Q _H3 are the same Refrigerant flow rate).

7 is a graph showing the optimum flow rate of the refrigerant when the heat of the engine coolant is larger than the heat of the exhaust gas.

Referring to FIG. 7, when the temperature QH1 of the engine cooling water and the temperature QH3 of the exhaust gas become larger than the reference temperature of the engine, the '4' point heated by the engine cooling water is higher than the '4' To the right. Therefore, the enthalpy increase amount from the '2' point to the '4' point heated by the heat of the engine cooling water is larger than that of FIG. 6, and the enthalpy increase amount from the '4' point to the '6' The refrigerant flow rate is optimized so that the heat of the engine cooling water and the heat of the exhaust gas can be utilized to the utmost.

The first waste heat recovery apparatus can determine the optimum refrigerant flow rate in the same manner as described with reference to Equations (1) and (2). That is, if the refrigerant flow rate is smaller than the optimum refrigerant flow rate, the heat recovery amount Q _H3 of the engine exhaust gas is reduced and the ORC output is reduced accordingly. Conversely, when the refrigerant flow rate is greater than the optimum refrigerant flow rate, the point '6' (i.e., the maximum temperature before the first inflator 23) moves below the reference in FIG. 6, The ORC output is reduced.

8 is a graph showing the optimum flow rate of the refrigerant when the heat of engine cooling water is smaller than the heat of the exhaust gas.

8, when the heat (Q _H1 ) of engine cooling water becomes smaller than the heat (Q _H3 ) of the exhaust gas, the '4' point heated by the engine cooling water becomes '4' To the left of the point. Therefore, the enthalpy increase amount from the '2' point to the '4' point heated by the heat of the engine coolant water is reduced as compared with the increase amount of the enthalpy from the '4' point to the '6' So that the heat of the engine cooling water and the heat of the exhaust gas can be utilized to the utmost.

9 is a view showing a second waste heat recovering apparatus according to another embodiment of the present invention.

9, the second waste heat recovering apparatus includes a first compressor 11, a first heat exchanger 13, a second heat exchanger 15, a third heat exchanger 17, a first regenerative heat exchanger 19 The second recuperator 33 and the second compressor 35. The second recuperator 23 is connected to the second recuperator 23 and the second recuperator 25 via the second recuperator 23, ). 1 and 8, the same reference numerals are used for the same constituent elements, and thus detailed description of the constituent elements shown in FIG. 1 is omitted.

As shown in Fig. 9, the second waste heat recovery apparatus further includes an exhaust gas recycling apparatus 31, a second inflator 33, and a second compressor 35 more than the first waste heat recovery apparatus.

The exhaust gas recirculation device 31 can perform the recirculation process of the exhaust gas whose temperature has been lowered by the second heat exchanger 15. In general, the exhaust gas recirculation device is subjected to a separate cooling process and then supplied to the engine 27 side, and the exhaust gas heat is discarded. In the case where the engine exhaust heat recovery apparatus is provided as in the present invention to utilize such waste heat that is discarded in the cooling process of the exhaust gas recirculation apparatus, the cooling process of the exhaust gas recirculation apparatus is performed by the second heat exchanger 3 heat exchanger 18 so as to perform heat exchange with the first refrigerant.

 That is, unlike a general exhaust gas recirculation apparatus having a cooling apparatus having a large heat capacity for cooling a high temperature exhaust gas to a low temperature, when the engine exhaust heat recovery apparatus is provided as in the present invention, the second heat exchanger 15 and the third A part of the exhaust gas at a relatively low temperature passed through the heat exchanger 18 is supplied to the engine 27 side at a predetermined proper temperature by a slight cooling by the exhaust gas recirculation device 31. [

In the second inflator (33), the exhaust gas whose temperature has been lowered by the second heat exchanger (15) can perform work. For example, if the second inflator 33 is a turbine, the exhaust gas will pass through the second inflator 33, causing the second inflator 33 to work. For example, the second expander (33) allows the second compressor (35) to work by the exhaust gas supplied from the second heat exchanger (15). Thereby, the second compressor (35) can inflow and compress atmospheric air. Generally, the air pressurized by the second compressor (35) is supplied to the engine through a separate cooling process. When the engine waste heat recovering device is provided as in the present invention, air compressed by the second compressor (35) Is supplied to the first heat exchanger (13) and the first regenerative heat exchanger (19), cooled by the first refrigerant, and supplied to the engine. That is, the first heat exchanger 13 and the first regenerative heat exchanger 19 further receive atmospheric air from the second compressor 35 and further transfer heat from the injected atmospheric air to the first refrigerant, Contributing to the improvement of the output of the microcomputer 23. The amount of heat discharged from the atmospheric air in the first heat exchanger 13 and the first regenerative heat exchanger 19 for heat exchange is Q _H6 .

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, And variations are possible. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be determined by the equivalents of the claims, as well as the following claims.

11: first compressor 13: first heat exchanger
15: second heat exchanger 17: third heat exchanger
19: first regenerative heat exchanger 21: second regenerative heat exchanger
23: first expander 25: first condenser
27: engine 31: exhaust gas recirculation device
33: second expander 35: second compressor

Claims (10)

And a condenser for condensing the refrigerant discharged from the compressor and supplying the refrigerant to the compressor, wherein the compressor, the compressor, the condenser, the evaporator, An engine waste heat recovery apparatus for recovering exhaust gas discharged from an engine and heat contained in cooling water by using an expander and a refrigerant circulating through the condenser,
(Hereinafter, referred to as "first refrigerant") flowing into the condenser and a refrigerant (hereinafter referred to as "second refrigerant") before flowing into the condenser, heat-exchanges the refrigerant with each other, group; And
And a second regenerative heat exchanger for receiving the second refrigerant before being introduced into the first regenerative heat exchanger and the first refrigerant discharged from the first regenerative heat exchanger, exchanging heat with each other, and discharging the second refrigerant. delete The method according to claim 1,
And a first heat exchanger for receiving the first refrigerant discharged from the first regenerative heat exchanger and the cooling water discharged from the engine, exchanging heat with each other, and discharging the refrigerant,
And the first refrigerant flowing into the second regenerative heat exchanger is the first refrigerant discharged from the first heat exchanger. The method of claim 3,
And a second heat exchanger for receiving the first refrigerant discharged from the first heat exchanger and the exhaust gas discharged from the engine, exchanging heat with each other, and discharging the discharged refrigerant. 5. The method of claim 4,
And a third heat exchanger for receiving the first refrigerant discharged from the second heat exchanger and the exhaust gas before being introduced into the second heat exchanger, exchanging heat with each other, and discharging the discharged refrigerant,
And the exhaust gas into which the second heat exchanger is introduced is exhaust gas discharged from the third heat exchanger. 5. The method of claim 4,
Further comprising: an exhaust gas recirculation device that receives a part of the exhaust gas discharged from the second heat exchanger, processes the exhaust gas so that the engine can be reused, and provides the engine to the engine side. 5. The method of claim 4,
And a third heat exchanger for receiving the first refrigerant discharged from the second heat exchanger and the exhaust gas discharged from the engine before being introduced into the second heat exchanger, exchanging heat with each other, and discharging the discharged refrigerant. Waste heat recovery device. 5. The method of claim 4,
Wherein the first heat exchanger further introduces atmospheric air from the turbocharger and exchanges heat between the atmospheric air and the first refrigerant discharged from the first regenerative heat exchanger. 9. The method of claim 8,
And a second inflator for allowing the exhaust gas discharged from the second heat exchanger to flow into the turbocharger. 9. The method of claim 8,
Wherein the first regenerative heat exchanger exchanges heat with the refrigerant flowing in from the compressor through the atmospheric air discharged from the second heat exchanger.

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