WO2021125939A1

WO2021125939A1 - Heavy-duty vehicle comprising a combustion engine.

Info

Publication number: WO2021125939A1
Application number: PCT/NL2020/050722
Authority: WO
Inventors: Cornelius Maria Rops; Patrique Bernhard Theodoor Herman Boerboom
Original assignee: Nederlandse Organisatie Voor Toegepast- Natuurwetenschappelijk Onderzoek Tno
Priority date: 2019-12-18
Filing date: 2020-11-19
Publication date: 2021-06-24
Also published as: EP3839221A1

Abstract

A heavy-duty vehicle (1) comprises an ORC system for waste heat recovery out of flue gas exhausted by the vehicle's combustion engine. The ORC system comprises a condenser (3) which is arranged in the slipstream of the vehicle's base structure (7). The overall width W of the condenser is in the range between 1.0 m and 3.0 m, the overall height H of the condenser is in the range between 1.0 m and 4.0 m, while the overall depth D of the condenser is in the range between 0.05W and 0.30W and in the range between 0.05H and 0.30H. Air-intake and air- outlet openings of the condenser are configured for realizing buoyancy flow of environmental air through the condenser. Thanks to the condenser's location, dimensions and configuration considerable improvements in energy savings are obtained as compared to previously proposed ORC systems for heavy-duty vehicles.

Description

Title: Heavy-duty vehicle comprising a combustion engine.

The invention relates to a heavy-duty vehicle comprising a combustion engine.

As used herein and as commonly known in the art, “heavy-duty vehicles” comprise trucks, buses and coaches. More particularly, as used herein, heavy-duty vehicles may be defined according to a known definition from the European Commission as freight vehicles of more than 3.5 tonnes (trucks) or passenger transport vehicles of more than 8 seats (buses and coaches). The heavy-duty vehicle fleet is very heterogeneous, with vehicles that have different uses and drive cycles. Even trucks are segmented into several categories, including long-haul, regional delivery, urban delivery and construction.

In practice, attempts have been made and are still being made to provide a heavy-duty vehicle with an organic rankine cycle system for waste heat recovery out of flue gas exhausted by the combustion engine. As used herein, an organic rankine cycle system is also called “ORC system”. In general, an ORC system typically comprises an evaporator, an expansion device (such as a turbine or other expander), a condenser and a working fluid pump. In an ORC system, an organic fluid is used. In the expansion device, the energy is recovered as work, which can be used to perform mechanical work and/or to generate electricity.

US 2017/0335723 Al discloses that an on-highway vehicle such as a truck might comprise a combustion engine and an organic rankine cycle system for waste heat recovery out of flue gas exhausted by the combustion engine. See paragraph [0017] of US 2017/0335723 Al: “on-highway vehicles such as cars and trucks”, and see Fig. 7 of US 2017/0335723 Al. In that sense it can be said that US 2017/0335723 Al discloses a heavy-duty vehicle according to the pre-characterizing portion of the appended independent claim 1 of the present invention.

However, ORC systems which have thus far been proposed for incorporation in a heavy-duty vehicle have not yet turned out to be of significant economical interest. The reason is that the energy savings obtained are relatively low as compared to the costs of incorporating such a proposed ORC system in a heavy-duty vehicle. One of the factors therein is that the condenser that has to be used in the ORC system needs considerable cooling, which is achieved via wind- intake opening structures in the heavy-duty vehicle and/or via electrical fans. Applying wind-intake opening structures comes at the price of increased aerodynamic resistance of the vehicle, while the application of electrical fans costs electrical energy. Evidently, these factors cost fuel.

It is an object of the invention to improve the energy savings obtained when an ORC system for waste heat recovery out of flue gas is incorporated in a heavy-duty vehicle.

For that purpose the invention provides a heavy-duty vehicle according to the appended independent claim 1. Preferable embodiments of the invention are provided by the appended dependent claims 2-11.

Hence the invention provides a heavy-duty vehicle comprising a combustion engine and an organic rankine cycle system for waste heat recovery out of flue gas exhausted by the combustion engine, wherein:

- said organic rankine cycle system is configured for performing organic rankine cycles with an organic working fluid which is heated by said flue gas;

- said organic rankine cycle system comprises a condenser for condensing said organic working fluid by heat transfer with environmental air of the heavy- duty vehicle;

- the heavy-duty vehicle has:

- a predefined forward straight driving direction, and

- a forward straight driving operation condition in which the heavy- duty vehicle is driving in said predefined forward straight driving direction; and

- the heavy-duty vehicle has mutually orthogonal vehicle directions in the form of a vehicle length direction, a vehicle width direction, and a vehicle height direction, said vehicle length direction being parallel to said predefined forward straight driving direction, said vehicle width direction extending horizontally when the vehicle is driving on a horizontal floor, and said vehicle height direction extending vertically when the vehicle is driving on a horizontal floor; characterized in that: - the condenser is arranged in a slipstream of a base structure of the heavy-duty vehicle, said base structure comprising a cabin of the heavy-duty vehicle, and said slipstream being defined as occurring in said forward straight driving operation condition of the heavy-duty vehicle;

- the condenser has mutually orthogonal condenser directions in the form of a condenser depth direction, a condenser width direction, and a condenser height direction, said condenser depth direction being parallel to said vehicle length direction, said condenser width direction being parallel to said vehicle width direction, and said condenser height direction being parallel to said vehicle height direction;

- the condenser has an overall depth D in said condenser depth direction, an overall width W in said condenser width direction, and an overall height H in said condenser height direction;

- said overall width W has a value in the range 1.0 m < W < 3.0 m;

- said overall height H has a value in the range 1.0 m < H < 4.0 m;

- said overall depth D has a value in the range 0.05W < D < 0.30W;

- said overall depth D has a value in the range 0.05H < D < 0.30H; and

- said condenser has at least one air-intake opening for allowing said environmental air to enter the condenser and at least one air-outlet opening for allowing said environmental air, when entered into and heated inside the condenser, to exit the condenser, wherein said at least one air-intake opening is located at a lower position along said height direction than said at least one air- outlet opening.

As used herein and as commonly known in the art, a “cabin” of a heavy- duty vehicle can be a truck-cabin, in case the heavy-duty vehicle is a truck, and can be a passenger compartment, in case the heavy-duty vehicle is a bus or a coach.

Some surprising key features of the heavy-duty vehicle according to the invention are summarized as follows. i. The condenser is arranged at a surprising location in the slipstream of the vehicle’s base structure. ii. The values of the overall width W, overall height H and overall depth D of the condenser are forming a surprisingly huge condenser for a heavy-duty vehicle. iii. Said at least one air-intake opening is surprisingly located at a lower position than said at least one air-outlet opening.

The combination of these surprising key features (i), (ii) and (iii) allows for a remarkably effective buoyancy flow of environmental air through the condenser. In other words, a kind of chimney effect is created according to which environmental air that is heated inside the condenser automatically rises up. The combination of these key features (i), (ii) and (iii) considerably improves the efficiency of the ORC system of the heavy-duty vehicle, without necessity to use wind-intake opening structures in the heavy-duty vehicle and/or electrical fans for the air-cooling of the condenser. Hence, this is achieved with more or less zero aerodynamic impact and zero electrical energy for cooling. This way the energy savings obtained for a heavy-duty vehicle are improved to such an extent that the present invention makes the application of an ORC system in a heavy-duty vehicle economically worth wile.

In a preferable embodiment of a heavy-duty vehicle according to the invention, said overall width W has a value in the range 1.5 m < W < 2.5 m.

In another preferable embodiment of a heavy-duty vehicle according to the invention, said overall height H has a value in the range 1.5 m < H < 2.5 m.

In another preferable embodiment of a heavy-duty vehicle according to the invention, said overall depth D has a value in the range 0.10W < D < 0.20W.

In another preferable embodiment of a heavy-duty vehicle according to the invention, said overall depth D has a value in the range 0.10H < D < 0.20H.

In another preferable embodiment of a heavy-duty vehicle according to the invention, said condenser comprises a condenser housing containing at least two flat condensing structures configured for containing said organic working fluid and for condensing said organic working fluid contained therein, wherein said at least two flat condensing structures are extending mutually parallel and perpendicularly to said condenser depth direction, and wherein said at least two flat condensing structures are mutually spaced in said condenser depth direction. It is remarked that, instead of the last-mentioned preferable embodiment in which the condenser comprises a condenser housing containing at least two flat condensing structures, the condenser of a heavy-duty vehicle according to the invention may, more generally, comprise a condenser housing which contains one, and only one, flat condensing structure which is configured for containing said organic working fluid and for condensing said organic working fluid contained therein, wherein said one, and only one, flat condensing structure is extending perpendicularly to said condenser depth.

The last-mentioned preferable embodiment in which the condenser comprises a condenser housing containing said at least two flat condensing structures, instead of only one flat condensing structure, has the advantage of improved condenser efficiency, at the price of only restricted additional space requirement for the condenser in the slipstream of the vehicle’s base structure.

In another preferable embodiment of a heavy-duty vehicle according to the invention, said condenser comprises a first interspace in-between two mutually neighbouring ones of said at least two flat condensing structures, wherein said first interspace is configured for containing said environmental air for heating of said environmental air, and wherein said first interspace has a first overall interspace dimension D1 in said condenser depth direction having a value in the range 5 cm < D1 < 15 cm. This further improves the condenser efficiency.

In another preferable embodiment of a heavy-duty vehicle according to the invention, said first interspace contains at least two first airfins, which are extending in said condenser height direction, and which are mutually spaced in said condenser width direction, and wherein each of said at least two first airfins is extending in said condenser depth direction in such manner that it is interconnecting said two mutually neighbouring ones of said at least two flat condensing structures. Said at least two first airfins provide for improved heat transfer from the organic working fluid to the environmental air, as well as for improved structural strength of the condenser structure.

In another preferable embodiment of a heavy-duty vehicle according to the invention, said condenser comprises a second interspace in-between said condenser housing and a neighbouring one of said at least two flat condensing structures, wherein said second interspace is configured for containing said environmental air for heating of said environmental air, and wherein said second interspace has a second overall interspace dimension D2 in said condenser depth direction having a value in the range 1 cm < D2 < 10 cm. This further improves the condenser efficiency.

In another preferable embodiment of a heavy-duty vehicle according to the invention, said second interspace contains at least two second airfins, which are extending in said condenser height direction, and which are mutually spaced in said condenser width direction, and wherein each of said at least two second airfins is extending in said condenser depth direction in such manner that it is interconnecting said condenser housing and said neighbouring one of said at least two flat condensing structures. Said at least two second airfins provide for improved heat transfer from the organic working fluid to the environmental air, as well as for improved structural strength of the condenser structure.

In another preferable embodiment of a heavy-duty vehicle according to the invention, said condenser is a first heat exchanger being assembled within a combined heat exchanging unit that is located in said slipstream of said base structure, and wherein said combined heat exchanging unit further comprises at least one further heat exchanger for heat transfer with environmental air of the heavy-duty vehicle, said at least one further heat exchanger having at least one further air-intake opening for allowing said environmental air to enter said at least one further heat exchanger and at least one further air-outlet opening for allowing said environmental air, when entered into and heated inside the condenser, to exit said at least one further heat exchanger, wherein said at least one further air- intake opening is located at a lower position along said height direction than said at least one further air-outlet opening. Thanks to said combined heat exchanging unit, said at least one further heat exchanger may benefit at least from advantages similar to the advantages of the condenser of the ORC system, i.e. improved efficiency of the at least one further heat exchanger of the heavy-duty vehicle, without necessity to use wind-intake opening structures in the heavy-duty vehicle and/or electrical fans for the air-cooling of the at least one further heat exchanger.

It is noted that said at least one further heat exchanger may for example be an engine oil heat exchanger and/or a transmission oil heat exchanger and/or an air- conditioning condenser and/or any other heat exchanger used in a heavy-duty vehicle.

In the following, the invention is further elucidated with reference to non limiting embodiments and with reference to the schematic figures in the appended drawing, in which the following is shown.

Fig. 1 shows, in a perspective view, an example of an embodiment of a heavy-duty vehicle according to the invention.

Fig. 2 shows, in a more detailed perspective view, the condenser of the ORC system of the heavy-duty vehicle of Fig. 1.

Fig. 3 shows the heavy-duty vehicle of Fig. 1 in a side view.

Fig. 4 shows the condenser of Fig. 1 in a cross-section perpendicular to the condenser width direction.

Fig. 5 shows, in a cross-section perpendicular to the condenser width direction, an example in which the condenser of Figs. 1-4 is assembled within an example of an embodiment of the above-mentioned combined heat exchanging unit.

The reference signs used in Figs. 1-5 are referring to the above-mentioned parts and aspects of the invention, as well as to related parts and aspects, in the following manner.

1 . heavy-duty vehicle

2 . combustion engine

3 . condenser of organic rankine cycle system

3A . further heat exchanger

3B . further heat exchanger

3C . further heat exchanger

4 . parts of organic rankine cycle system, other than the condenser

5 . organic working fluid

6 . environmental air

7 . base structure

8 . at least one air-intake opening

8A . at least one further air-intake opening

8B . at least one further air-intake opening 8C . at least one further air-intake opening

9 . at least one air-outlet opening

9A . at least one further air-outlet opening

9B . at least one further air-outlet opening

9C . at least one further air-outlet opening

10 . condenser housing

11 . flat condensing structure

12 . flat condensing structure

14 . combined heat exchanging unit

15 . vapour supply pipe

16 . T-connection piece

17 . liquid discharge pipe structure

21 . first interspace

22A . second interspace

22B . second interspace

31 . first airfin

32A . second airfin

32B . second airfin

F . predefined forward straight driving direction

Xc . condenser depth direction

Yc . condenser width direction

Zc . condenser height direction

Xv . vehicle length direction

Yv . vehicle width direction

Zv . vehicle height direction

Based on the above introductory description, including the brief description of the drawing figures, and based on the above-listed reference signs used in Figs. 1-5, the examples of Figs. 1-5 are readily self-explanatory. The following extra explanations are given.

The heavy-duty vehicle 1 of Figs. 1 and 3 is a truck, wherein the base structure 7 of the truck is formed by a cabin and a cabin top deflector mounted on top of the cabin. The ORC system of the vehicle 1 comprises the condenser 3, which is located in the slipstream of the base structure 7. Other parts of the ORC system have been shown and indicated highly schematically by item 4 in Fig. 1. It is noted that, in case the heavy-duty vehicle would be a bus, the condenser can be located in the slipstream on, for example, the backside of the bus.

In the shown example, the condenser 3 substantially has the shape of a rectangular parallelepiped having the overall depth D, the overall width W and the overall height H as mentioned above. In the perspective view of Fig. 2 and in the side view of Fig. 3 the condenser 3 is shown partly in ghost view, so as to indicate some internal parts within the housing 10 of the condenser 3. The indicated internal parts are the two flat condensing structures 11, 12, the first interspace 21, and the two second interspaces 22A, 22B. In Fig. 2 it is seen that the environmental air 6 enters the condenser 3 via the lower air-intake openings 8 and exits the condenser 3 via the upper air-outlet openings 9. In the first interspace 21 and the two second interspaces 22A, 22B the environmental air 6 is heated by heat transfer from the organic working fluid 5 inside the two flat condensing structures 11, 12.

In Fig. 2 the reference numerals 5 serve to indicate that the organic working fluid 5 may enter the two flat condensing structures 11, 12 from above in gaseous form and may exit the two flat condensing structures 11, 12 from below in condensed form. This is also illustrated by the cross-sectional view of Fig. 4, which illustrates that, in the shown example, a vapour supply pipe 15 is used that is extending from under the condenser 3 upwardly into and through the first interspace 21 and then connects via a T-connection piece 16 with top inlets of the two flat condensing structures 11, 12. Fig. 4 further illustrates that, in the shown example, a liquid discharge pipe structure 17 is connected to bottom outlets of the two flat condensing structures 11, 12.

Fig. 2 further indicates upper parts of the first airfins 31, the second airfins 32A and the second airfins 32B, which are extending in the first interspace 21, the second interspace 22 A and the second interspace 22B, respectively. In the shown example, although not visibile in Fig. 2, these first and second airfins 31, 32A, 32B are extending in the condenser height direction Zc along the full height H of the condenser 3. Fig. 4 further indicates, for the first interspace 21, the first overall interspace dimension Dl; for the second interspace 22 A, the value D2A of the second overall interspace dimension D2; and for the second interspace 22B, the value D2_B of the second overall interspace dimension D2. All these dimensions are as measured in the condenser depth direction Xc.

Fig. 5 shows the combined heat exchanging unit 14, which comprises the condenser 3 with its at least one air-intake opening 8 and its at least one air-outlet opening 9, wherein the condenser 3 is the condenser of the ORC system of the heavy- vehicle 1. In addition the combined heat exchanging unit 14 comprises the further heat exchanger 3A with its at least one air-intake opening 8A and its at least one air-outlet opening 9A, the further heat exchanger 3B with its at least one air-intake opening 8B and its at least one air-outlet opening 9B, and the further heat exchanger 3C with its at least one air-intake opening 8C and its at least one air-outlet opening 9C. The further heat exchanger 3A may for example be an engine oil heat exchanger. The further heat exchanger 3B may for example be a transmission oil heat exchanger, and the further heat exchanger 3C may for example be an air-conditioning condenser.

Claims

1. A heavy-duty vehicle (1) comprising a combustion engine (2) and an organic rankine cycle system (3, 4) for waste heat recovery out of flue gas exhausted by the combustion engine, wherein:

- said organic rankine cycle system is configured for performing organic rankine cycles with an organic working fluid (5) which is heated by said flue gas;

- said organic rankine cycle system comprises a condenser (3) for condensing said organic working fluid by heat transfer with environmental air (6) of the heavy-duty vehicle;

- the heavy-duty vehicle has:

- a predefined forward straight driving direction (F), and

- a forward straight driving operation condition in which the heavy- duty vehicle is driving in said predefined forward straight driving direction (F); and

- the heavy-duty vehicle has mutually orthogonal vehicle directions in the form of a vehicle length direction (Xv), a vehicle width direction (Yv), and a vehicle height direction (Zv), said vehicle length direction (Xv) being parallel to said predefined forward straight driving direction (F), said vehicle width direction (Yv) extending horizontally when the vehicle is driving on a horizontal floor, and said vehicle height direction (Zv) extending vertically when the vehicle is driving on a horizontal floor; characterized in that:

- the condenser is arranged in a slipstream of a base structure (7) of the heavy-duty vehicle, said base structure comprising a cabin of the heavy-duty vehicle, and said slipstream being defined as occurring in said forward straight driving operation condition of the heavy-duty vehicle;

- the condenser has mutually orthogonal condenser directions in the form of a condenser depth direction (Xc), a condenser width direction (Yc), and a condenser height direction (Zc), said condenser depth direction (Xc) being parallel to said vehicle length direction (Xv), said condenser width direction (Y_c) being parallel to said vehicle width direction (Yv), and said condenser height direction (Zc) being parallel to said vehicle height direction (Zv);

- the condenser has an overall depth D in said condenser depth direction (Xc), an overall width W in said condenser width direction (Yc), and an overall height H in said condenser height direction (Zc);

- said overall width W has a value in the range 1.0 m < W < 3.0 m;

- said overall height H has a value in the range 1.0 m < H < 4.0 m;

- said overall depth D has a value in the range 0.05W < D < 0.30W;

- said overall depth D has a value in the range 0.05H < D < 0.30H; and

- said condenser has at least one air-intake opening (8) for allowing said environmental air to enter the condenser and at least one air-outlet opening (9) for allowing said environmental air, when entered into and heated inside the condenser, to exit the condenser, wherein said at least one air-intake opening is located at a lower position along said height direction than said at least one air- outlet opening.

2. A heavy-duty vehicle according to claim 1, wherein said overall width W has a value in the range 1.5 m < W < 2.5 m.

3. A heavy-duty vehicle according to any one of the preceding claims, wherein said overall height H has a value in the range 1.5 m < H < 2.5 m.

4. A heavy-duty vehicle according to any one of the preceding claims, wherein said overall depth D has a value in the range 0.10W < D < 0.20W.

5. A heavy-duty vehicle according to any one of the preceding claims, wherein said overall depth D has a value in the range 0.10H < D < 0.20H;

6. A heavy-duty vehicle according to any one of the preceding claims, wherein said condenser comprises a condenser housing (10) containing at least two flat condensing structures (11, 12) configured for containing said organic working fluid and for condensing said organic working fluid contained therein, wherein said at least two flat condensing structures are extending mutually parallel and perpendicularly to said condenser depth direction (Xc), and wherein said at least two flat condensing structures are mutually spaced in said condenser depth direction (Xc).

7. A heavy-duty vehicle according to claim 6, wherein said condenser comprises a first interspace (21) in-between two mutually neighbouring ones of said at least two flat condensing structures, wherein said first interspace is configured for containing said environmental air for heating of said environmental air, and wherein said first interspace has a first overall interspace dimension D1 in said condenser depth direction (Xc) having a value in the range 5 cm < D1 < 15 cm.

8. A heavy-duty vehicle according to claim 7, wherein said first interspace (21) contains at least two first airfins (31), which are extending in said condenser height direction (Zc), and which are mutually spaced in said condenser width direction (Yc), and wherein each of said at least two first airfins is extending in said condenser depth direction (Xc) in such manner that it is interconnecting said two mutually neighbouring ones of said at least two flat condensing structures.

9. A heavy-duty vehicle according to any one of claims 6-8, wherein said condenser comprises a second interspace (22A, 22B) in-between the condenser housing and a neighbouring one of said at least two flat condensing structures, wherein said second interspace is configured for containing said environmental air for heating of said environmental air, and wherein said second interspace has a second overall interspace dimension D2 in said condenser depth direction (Xc) having a value in the range 1 cm < D2 < 10 cm.

10. A heavy-duty vehicle according to claim 9, wherein said second interspace contains at least two second airfins (32 A, 32B), which are extending in said condenser height direction (Zc), and which are mutually spaced in said condenser width direction (Yc), and wherein each of said at least two second airfins is extending in said condenser depth direction (Xc) in such manner that it is interconnecting said condenser housing and said neighbouring one of said at least two flat condensing structures.

11. A heavy-duty vehicle according to any one of the preceding claims, wherein said condenser (3) is a first heat exchanger (3) being assembled within a combined heat exchanging unit (14) that is located in said slipstream of said base structure, and wherein said combined heat exchanging unit further comprises at least one further heat exchanger (3A, 3B, 3C) for heat transfer with environmental air of the heavy-duty vehicle, said at least one further heat exchanger having at least one further air-intake opening (8A, 8B, 8C) for allowing said environmental air to enter said at least one further heat exchanger and at least one further air- outlet opening (9A, 9B, 9C) for allowing said environmental air, when entered into and heated inside the condenser, to exit said at least one further heat exchanger, wherein said at least one further air-intake opening is located at a lower position along said height direction than said at least one further air-outlet opening.