Patent Application
20130112382
This nonprovisional application is a continuation of International Application No. PCT/EP2010/065899, which was filed on Oct. 21, 2010, and which claims priority to German Patent Application No. DE 10 2009 050 889.9, which was filed in Germany on Oct. 27, 2009, and which are both herein incorporated by reference.
1. Field of the Invention
The present invention relates to an evaporator, in particular an exhaust gas evaporator, for an exhaust gas system of a motor vehicle.
2. Description of the Background Art
The recovery of thermal energy from exhaust gases of an internal combustion engine is growing steadily in importance in the area of automotive engineering. In particular, the focus is increasingly on the recovery of thermal energy with the aid of exhaust gas evaporators in order to thereby increase efficiency with regard to the operation of the internal combustion engine. In an exhaust gas evaporator, heat is removed from the exhaust gas and supplied to a coolant or refrigerant, which is usually evaporated during this process. The thermal energy removed from the exhaust gas may be used for a downstream Clausius-Rankine process.
For example, DE 10 2007 060 523 A1, which corresponds to US 20100319887, and which is incorporated herein by reference, discloses an exhaust gas evaporator, the exhaust gas evaporator having a sandwich design in which exhaust gas planes and coolant planes are alternately disposed immediately next to each other.
It is therefore an object of the invention to provide an evaporator which is improved with regard to its pressure stability and which is also easy and cost-effective to manufacture.
According to an embodiment of the invention, the evaporator, which is suitable, in particular, for use as an exhaust gas evaporator for an exhaust gas system of a motor vehicle, has a plate sandwich structure including multiple fluid-guiding plate elements which are stacked on top of each other for guiding a first fluid, at least one rib, in particular a connecting rib or a corrugated rib, being disposed between two plate elements for guiding a second fluid, a plate element comprising at least one cover plate covering a flow channel and a flow channel plate unit, the flow channel plate having at least one flow channel plate provided with flow channels in order to guide the first fluid from an inlet to an outlet.
Representing the evaporator in a plate sandwich structure provides the evaporator with a particularly high pressure stability, and it may thus sufficiently withstand the working pressures of up to 100 bar, which occur, for example, in a Clausius-Rankine process.
In an embodiment, the flow channel plate unit comprises a single flow channel plate, the flow channel plate being closed by a cover plate covering the flow channel. A specific embodiment of this type represents the simplest and most cost-effective design of a flow channel plate unit.
In a further embodiment, another cover element is provided which is disposed between the single flow channel plate and the at least one rib, so that the flow channel plate is disposed between the two cover plates.
In other words, plate elements in the sequence of cover plate—flow channel plate—cover plate are disposed between two ribs, so that the two cover plates represent a good contact surface or a flat connection to the rib.
In a further embodiment, the flow channel plate unit comprises exactly two flow channel plates, which are disposed between two cover plates. Due to the integral connection of the two channel plates, a channel structure is provided which has an increased pressure resistance.
The flow channels of the flow channel plates are preferably provided by means of an embossing process or a deep-drawing process. Methods of this type are cost-effective and, in addition, this method makes it possible to introduce different channel structures into the flow channel plates. For example, a meander-shaped channel structure is conceivable, in which the first fluid, for example water or an alcohol mixture of a Clausius-Rankine cycle, may be guided from an inlet to an outlet.
In another embodiment, the flow channels are formed by parallel seams which are connected to each other by openings. Due to a specific embodiment of this type, a particularly easy-to-manufacture flow channel plate is provided, it being possible to introduce the in particular stamped channels at any point, depending on the application.
In another embodiment, the flow channels of the flow channel plates are designed as openings, the openings in the two flow channel plates overlapping to form one or multiple flow channels. The overlapping openings are preferably designed to have different widths, so that any burrs that may be present on the edges of the openings do not hinder the fluid interconnection of the flow channels.
The openings can be provided by means of a stamping process, by laser cutting or water jet cutting.
In another embodiment, the inlet and/or the outlet is/are disposed in a central area of the evaporator. A specific embodiment of this type achieves the fact that a thermal expansion, in particular in a longitudinal direction of the evaporator, is not hindered. According to the invention, a “central area” is understood to be an area which extends 0 to 20 percent, preferably 0 to 10 percent, of the entire length of the evaporator in both directions from the geometric center of the evaporator.
In another embodiment, the inlet and/or the outlet is/are disposed on the side of the evaporator so as not to hinder the flow of the second fluid, in particular an exhaust gas of a motor vehicle. The plate elements, which have an essentially rectangular design, have projections with openings on both longitudinal sides for this purpose. Stacking the individual plate elements forms an inlet having an inlet collecting channel, on the one hand, and a corresponding outlet having an outlet collecting channel, on the other hand.
In another embodiment, at least one, preferably each, flow channel plate unit has an element which is designed to generate an elevated pressure loss. The element is preferably designed as a nozzle, an aperture or a labyrinth. A specific embodiment of this type achieves the fact that the pressure loss difference between the individual flow channels of different flow channel plate units is lower in terms of percentage by selectively introducing a “preliminary pressure loss.” This ensures uniform medium distribution of the first fluid to the respective flow channel plate units.
An evaporator of this type can be used as an exhaust gas evaporator in an exhaust gas system of a motor vehicle, it being possible to couple an exhaust gas evaporator of this type to a Clausius-Rankine cycle.
It is understood that the aforementioned features and the features still to be explained below may be used not only in the combinations indicated but also in other combinations or alone without going beyond the scope of the present invention.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.
The present invention will become more fully understood from the detailed description given hereinbelow and the accompanying drawings which are given by way of illustration only, and thus, are not limitive of the present invention, and wherein:
a to 2d show schematic representations of a view of different flow channel plates;
Motor vehicle 1 shown in
As furthermore shown in
a through
If a stack of plate elements 15 of this type is then constructed by alternately placing one plate element 15 and one rib 16 on top of each other and subsequently soldering them to each other, this results in an exhaust gas evaporator, as shown in
The exhaust gas evaporator has an inlet 13 and an outlet 14 which are disposed approximately in the center, viewed in the longitudinal direction. The fluid, for example water from a Clausius-Rankine cycle, flows from inlet 13 into a collecting channel 13a, which is formed by plate elements 15 and intermediate elements 13b inserted between them.
From there, the fluid is distributed to the respective plate elements and, once it has been collected in a second collecting channel 14a, flows out of the evaporator through outlet 14. Second collecting channel 14a is also formed from respective plate elements 15 and intermediate elements 14b inserted inbetween. The two collecting channels 13a and 14a are disposed on the side of the evaporator so that the flow of the second fluid, in particular an exhaust gas of a motor vehicle, is not hindered along ribs 16.
As demonstrated by the exemplary embodiment according to
As shown in
Due to the provision of a pressure loss “dp,” the pressure loss difference through different zones 22 through 24 is lower in terms of percentage. This measure ensures a more uniform distribution of medium. The ratio between the preliminary pressure loss and the pressure loss in the rest of flow channel 17 should thus be between 0.25 and 1.
The additional pressure loss does not produce any major losses in the overall efficiency of the Clausius-Rankine cycle, since the power of pump 21 increases only minimally due to the low mass flows caused by the additional overall pressure loss via evaporator 5.
In another exemplary embodiment according to
The level of the mass flows varies, depending on the working fluid selected. For example, a parallel disposition of flow channels 17 is suitable for alcohols, as shown in
Under certain circumstances, this second cover plate 11 may be eliminated so that flow channel plate 12a directly adjoins rib 16.
The specific embodiment according to
If necessary, lower second cover plate 11 may also be omitted in this specific embodiment.
Based on a plurality of tests, the following geometric parameters have proven to be particularly favorable:
0.5 mm≦h≦3 mm, preferably: 0.8 mm≦h≦2 mm;
mm≦b1≦8 mm, preferably: 3.0 mm≦b1≦5 mm;
mm≦b2≦8 mm, preferably: 3.0 mm≦b2≦5 mm;
where: b2<b1;
0.5 mm≦c1≦3 mm, 0.5 mm≦c2≦3 mm, where: c1<c2;
The thicknesses of cover plates 11 are preferably 0.5 mm to 0.8 mm. The thickness of the at least one flow channel plate is preferably between 0.3 mm and 0.7 mm; this means that the at least one flow channel plate may be of a thinner design than the at least one cover plate.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the invention, and all such modifications as would be obvious to one skilled in the art are to be included within the scope of the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| DE102009050889.9 | Oct 2009 | DE | national |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/EP2010/065899 | Oct 2010 | US |
| Child | 13457974 | US |
