EP1982057A2

EP1982057A2 - Liquid cooling device in internal combustion engines and process for manufacturing same

Info

Publication number: EP1982057A2
Application number: EP07704150A
Authority: EP
Inventors: Claudius Kormann; Gerd Kaibel; Dirk Neumann
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2006-01-27
Filing date: 2007-01-26
Publication date: 2008-10-22
Also published as: KR20080087878A; WO2007085641A3; CN101375032B; CN101375032A; WO2007085641A2; US20100162971A1; JP2009524763A

Abstract

The invention relates to a liquid cooling device in an internal combustion engine (11) and to a process for manufacturing same. The device according to the invention comprises a cooling circuit (13) having at least one cooling duct (23, 24, 41) for a liquid coolant, the duct being in thermal contact with at least one component (12a, 12b, 31) of the internal combustion engine (11). A wall of the cooling duct (23, 24, 41) that comes into contact with the coolant comprises in at least one partial zone a microstructured surface with a certain porosity and roughness. According to the invention, this device is produced by forming a cooling circuit for a liquid coolant, the circuit comprising cooling ducts that can be brought at least in part into thermal contact with the internal combustion engine, and by generating a microstructured surface on at least part of the walls of the cooling ducts that come into contact with the liquid coolant.

Description

Apparatus for liquid cooling of internal combustion engines and process for their production

description

The invention relates to a device for liquid cooling of internal combustion engines and a method for their preparation.

In the operation of internal combustion engines, such as reciprocating engines, such as the diesel or diesel used in the vehicle sector

Otto engines, arise in the combustion chambers of the cylinders temperatures of over 2000 ° C. The transferred from the cylinders via the cylinder walls to the engine block and the cylinder head heat is a danger to other limited heat resistant components of the internal combustion engine and must therefore be removed as efficiently as possible in order to prevent damage to these components by overheating.

From the prior art it is known to cool internal combustion engines with air or a liquid as the cooling medium. In this case, particular preference is given to liquid cooling with water as the cooling liquid, because the high heat capacity and the low viscosity of water enable efficient cooling of the internal combustion engine. In a water-cooled internal combustion engine cooling channels are arranged, for example, in the walls of the cylinder jacket and / or the cylinder head and / or in the crankcase, which form part of a cooling circuit through which the cooling water is passed. In an arranged outside of the internal combustion engine portion of the cooling circuit is an air-cooled heat exchanger, which is referred to in motor vehicles as a cooler and through which the cooling water releases the heat absorbed in the internal combustion engine to the environment. Usually, the cooling liquid enters a deeper area in the

Internal combustion engine and is passed through cooling channels or cooling jackets of the engine block / crankshaft housing in the cylinder head, from where it exits in a higher-lying area of the internal combustion engine. However, it is also known to divide the coolant by means of a preferably controllable valve before entering the motor housing into two separate subcircuits and to conduct separately into the cooling channels or cooling jackets of the crankcase and the cylinder head. In the cooling circuit, other heat exchangers, compressors and

Be arranged capacitors, which cooperate with the heating system or the air conditioning of the motor vehicle. For example, the heat emitted by the internal combustion engine can be used at least for heating the passenger compartment. It is also known to cool the hot exhaust gases of an internal combustion engine via suitable heat exchangers. In this case, for example, the heat energy withdrawn from the hot exhaust gases can be used in the starting phase to heat the cooling liquid, so that the internal combustion engine through which the cooling liquid flows reaches its optimum operating temperature more quickly. Cooling of the exhaust gases is, however, particularly advantageous in so-called exhaust gas recirculation systems, which have recently been used in the automotive sector, on the one hand to reduce consumption in the partial load range and, on the other hand, to reduce the emissions of the internal combustion engines, especially the NO _x emission. In this case, a part of the exhaust gas, which is usually controllable via valves, is returned to the intake tract of the internal combustion engine. The effects of exhaust gas recirculation on fuel consumption and NO _x reduction can be further improved if the recirculated exhaust gas partial flow is cooled by means of an exhaust gas cooler.

The circulation of the cooling liquid is usually carried out by a pump arranged in the cooling pump, which is usually directly driven by a V-belt from the internal combustion engine, so that a dependent of the engine speed coolant flow is generated. In order for the internal combustion engine to reach its optimum operating temperature quickly, it is also known to bridge the radiator via a thermostat-controlled valve in the warm-up phase of the internal combustion engine.

In addition to a recording of heat generated in the internal combustion engine by heating the cooling liquid occurs in areas with a particularly high heat load in addition to a partial evaporation of the cooling liquid, so that over the corresponding enthalpy of vapor highly effective cooling of the corresponding engine surfaces can be effected.

In modern internal combustion engines today not only water is used as a cooling liquid, but one commonly referred to as coolant

Liquid that contains other additives in addition to water, primarily additives that serve the antifreeze and corrosion protection.

Coolant compositions for the cooling circuits of internal combustion engines, as used in motor vehicles, contain water in addition to most Alkylene glycols, mainly ethylene glycol and / or polyglycol and / or glycerin as antifreeze component.

From EP-A-816467 it is known, for example, to use not only the alkylene glycols but also higher glycols and glycol ethers as antifreeze components.

Since components of internal combustion engines are subjected to high temperature loads, both by the absolute temperatures prevailing during operation and by temperature fluctuations, any type and extent of corrosion represents a potential risk factor, which leads to shortening of the running time of the internal combustion engine and reduction of its reliability can. The variety of materials used in a modern internal combustion engine, such as cast iron, copper, brass, soft solder, steel and light alloys, especially magnesium and aluminum alloys, create additional potential corrosion problems, particularly at the points where different metals are in contact. At these points can be very easily different types of corrosion, such as pitting corrosion, steel corrosion, erosion or cavitation occur. Therefore, modern coolant compositions also contain special corrosion inhibitors which serve as anti-corrosive components. DE-A 195 474 49, EP-A 0 552 988 or US Pat. No. 4,561,990, for example, disclose cryoprotectants for the cooling water of internal combustion engines which contain carboxylic acids, molybdates or triazoles. EP-A-0 229 440 describes a corrosion inhibiting component of an aliphatic monobasic acid, a dibasic hydrocarbon acid and a hydrocarbyltriazole. Special acids as corrosion protection components are described, for example, in EP-A 0 479 470. Quaternized imidazoles as corrosion protection component are known from DE-A 196 05 509. The coolant compositions must also be designed to be compatible with non-metallic components of the refrigeration cycle, such as elastomers and other plastics from hose joints or gaskets, and not alter or even attack them.

In addition to the continuous improvement of the anti-freezing and anti-corrosion components of a coolant composition, recent technical developments are aimed in particular at improving the cooling properties of the coolant. For example, it has been proposed to improve the cooling properties by additives which reduce the viscosity and / or the flow resistance of the cooling liquid in the cooling circuit.

The achievable power density of an internal combustion engine is significantly influenced by the efficiency of the liquid cooling. The present The invention is therefore based on the technical problem of providing a device for liquid cooling internal combustion engines, in particular using the liquid coolant described above, in which the cooling effect, in particular on thermally highly stressed surfaces of the internal combustion engine, is further improved. The invention also relates to a method for producing such a device.

This technical problem is solved by the device for liquid cooling of an internal combustion engine with the features of the present claim 1. Advantageous developments of the device according to the invention are subject matters of the dependent claims.

The invention accordingly relates to a device for cooling an internal combustion engine with a cooling circuit comprising at least one cooling channel for a liquid coolant which is in thermal contact with at least one component of the internal combustion engine, wherein the device according to the invention is characterized in that one with the coolant in Contact coming wall of the cooling channel at least in a partial area has a microstructured surface. When in the present description of a liquid coolant is mentioned, this refers to the

State of aggregation of the coolant at temperatures between 0 to 100 ° C and atmospheric pressure. Depending on the antifreeze component used, the coolant may also be liquid at lower or higher temperatures.

While in the known from the prior art cooling circuits for internal combustion engines is usually sought as smooth as possible with the liquid coolant contacting surfaces of the cooling circuit lines, thereby minimizing the flow resistance of the coolant, it has now surprisingly found that with the inventively modified cooling device a significantly better cooling effect can be achieved without significantly impairing the flow properties of the coolant. It has been found, in particular, that the microstructured surface of the cooling device according to the invention leads both to an improvement of the single-phase heat transfer before onset of boiling of the coolant and to a drastic improvement of the biphasic heat transfer, in particular the boiling efficiency and the boiling activity in the region of the bubbling. For example, it has been found that wall overheating, that is, the temperature difference between wall temperature T _w and saturation temperature T _{s of} the coolant at the onset of bubble boiling could be reduced from a range of about 20 to 40 ° C to a range of about 3 to 10 ° C , With the inventive device for liquid cooling of internal combustion engines is therefore possible to improve the cooling of the internal combustion engine crucial. Since, as mentioned above, the power density of modern internal combustion engines is often limited by the efficient heat removal by cooling, it allows the inventive

Device also to increase the power density of internal combustion engines.

Different components of an internal combustion engine can be cooled by the cooling channels with microstructured surface provided according to the invention. In the first place, the cooling channels are in thermal contact with components of the engine block of the internal combustion engine, for example with the cylinder head and / or the crankcase. However, the term "components of the internal combustion engine" within the meaning of the present invention also includes components outside the actual engine block, in particular further arranged in the cooling system of the internal combustion engine heat exchanger, such as exhaust gas cooler or oil cooler. These heat exchangers each have separate Kühlflüssigkeitskreislaufe; However, they are preferably cooled via partial circuits of the cooling circuit of the internal combustion engine, wherein the distribution of the cooling liquid flow in the individual sections is particularly preferably controlled by suitable valves.

According to an advantageous embodiment of the device according to the invention, the microstructured surface has an average surface roughness Ra in the range from 1 to 1500 .mu.m, preferably in the range from 20 to 200 .mu.m.

Particularly preferably, the microstructured surface has a porous structure. The pore size of the porous microstructures is advantageously in the range of 1 to 500 microns. The pore size refers to the largest pore diameter in cross section. For example, the pores may have a substantially circular cross-sectional area, but any other pore geometries are also possible. The proportion of pores in the microstructured surface layer may be in a range from 1 to 90%, preferably in a range from 10 to 80% and particularly preferably in the range from 10 to 70%.

The rough and / or porous microstructures of the device according to the invention can be distributed regularly or stochastically on the surface. The preferred pore depth corresponds to a stochastic arrangement of the pores approximately the pore diameter. Particularly in the case of a mechanical incorporation of the pores into the surface, it is possible to move from round pore shapes to any desired geometric shapes, for example differently profiled longitudinal channels. The depth of the pores or of the channels or other depressions is thereby regardless of the pore width. The layer thickness of the microstructured surface is preferably in the range of a few micrometers to a few millimeters, for example in the range of 1 to 10,000 microns, preferably in the range of 10 to 1000 microns.

According to a variant of the device according to the invention, the entire wall surface of the lines and channels of the cooling circuit coming into contact with the liquid coolant can be designed as a microstructured surface. According to a preferred variant, however, the microstructured surfaces are limited to areas of the cooling circuit that are in the area to be cooled

Internal combustion engine are located and / or optionally arranged in the cooling circuit heat exchangers for cooling hot gases, such as the above-mentioned exhaust gas cooler.

As the liquid coolant, it is preferable to use the above-described water-based alkylene glycol-containing coolant compositions. The coolant may according to a preferred variant of the device according to the invention contain surface-active additives, such as surfactants, which reduce the surface tension of the coolant. Such surface-active additives additionally facilitate the boiling process by further reducing wall overheating required for onset of bubble boiling.

Usually cooling circuits of modern internal combustion engines are operated at a pressure of 1, 5 to 5 bar absolute to increase the saturation temperature of the liquid coolant and thus to further improve the cooling effect.

The invention also relates to a method for producing the device according to the invention for liquid cooling of internal combustion engines. According to the invention forms a cooling circuit for a liquid coolant having cooling channels, which are at least partially in thermal contact with the internal combustion engine, wherein at least on a part of the coming into contact with the liquid coolant walls of the cooling channels generates a microstructured surface.

Methods for producing cooling circuits for internal combustion engines, in particular internal combustion engines, are known to the person skilled in the art, so that the following statements may be limited to the production of the microstructured surfaces provided according to the invention. The inner wall of the cooling channel on which the microstructured surface is formed preferably consists of a good heat-conducting material, in particular of metal. Particularly preferably, the channels are already formed during the casting of the internal combustion engine, then that the channel wall is usually made of the same material as the engine block, the

Cylinder head cover or the crankcase is made.

According to a first variant of the method according to the invention, the microstructured surface is produced by mechanical processing of the inner walls of the cooling channels. For example, suitable microstructures can be produced by machining the walls, such as milling grooves and other depressions, or by impressing structures by means of correspondingly profiled rolling rolls or disks. Suitable microstructured coatings, as can also be used in the device according to the invention, are known, for example, from chemical engineering. Wieland-Werke AG, Ulm, Germany, for example, produces heat exchanger tubes under the name "Enhanced Boiling Tubes." Mechanically applied microstructures serve to improve the heat transfer during vaporization

Production of such structures are described, for example, in EP-A 0 607 839, DE-C 101 56 374, DE-C 44 04 357 and DE-A-102 10 016.

Microstructuring of the highly thermally stressed walls can also be produced, for example, by abrasive machining of the walls, for example by blasting with sand, metal or ceramic beads or other abrasive particles. The microstructured surface layer can also be produced by chemical treatment of the walls, for example by etching the wall surface with suitable acids or bases.

According to a further variant of the method according to the invention, the microstructured surface is produced by depositing a rough and / or porous layer on the walls to be processed. The microstructured surface may in this case also consist of a different material than the inner wall of the cooling channels. Various methods known from coating technology can be used, such as flame spraying, PVD or CVD processes, powder or plasma coatings, sputtering or various spraying or sputtering processes. It is also possible to use coatings known from the patented "High-Flux Tubes" porous coated pipes from UOP LLC, Despaines, IL, USA, in which there is an improvement in the heat transfer during evaporation A method for producing such porous layers by applying a porous foam and then plating the foam is described in US-A 4,136,427 Other processes for producing suitable layers are JP-A 2001-038463 or FR-A-0122, for example 782 described in which metal particles of suitable particle size by a solder material to a porous Surface layer are joined together. Another possibility is to add an additive to the coolant, which decomposes thermally and thereby forms degradation products, which precipitate on the cooling surface as a porous coating.

According to a particularly preferred variant of the method according to the invention, the microstructured surface is produced directly during the casting of the internal combustion engine. In this case, the casting mold can already have a corresponding microstructure. A particularly simple possibility, however, is to superficially coat the moldings for the cavities of the engine block with a slurry or a slurry of metal and / or ceramic particles of corresponding particle size and a polymer which decomposes during the casting process during the casting process of the engine block.

The invention will be explained in more detail below with reference to an embodiment shown schematically in the accompanying drawing and based on comparative experiments carried out in a Siedeprüfstand.

In the drawing shows:

Figure 1 is a schematically illustrated device for liquid cooling a

Internal combustion engines; FIG. 2 shows boiling curves which show the aging behavior of a cast sleeve provided with a microstructured surface according to the invention;

FIG. 3 shows boiling curves of a comparative experiment of a novel process

Cast sleeve and an unmodified cast sleeve; and FIG. 4 shows boiling curves of a further comparative test of cast casings according to the invention and unmodified cast casings at different flow velocities.

In Fig. 1, a device 10 according to the invention for the liquid cooling of an internal combustion engine 11 is shown schematically. In the example shown, the internal combustion engine 1 1 is designed as an internal combustion engine having a cylinder head 12 a and a crankcase engine block 12 b. Of the

Internal combustion engine 1 1 is cooled by a coolant circulating in a cooling circuit 13. The cooling circuit 13 has a delivery pump 14 and an external, air-cooled main heat exchanger 15, which is usually referred to as "radiator" in a motor vehicle. <br/><br/> A thermostat valve 17 controlled by a temperature sensor 16 is arranged in front of the inlet of the radiator 15, which depends on the coolant flow from the operating conditions of Internal combustion engine, either in a large circuit 18, which passes through the heat exchanger 15, or in a small circuit 19, which bridges the heat exchanger 15.

The coolant flow coming from the main heat exchanger 15 enters the internal combustion engine 11 via a coolant inlet 20 arranged in the region of the crankcase 12b. Depending on the number of cylinders of the engine, the coolant flow in the internal combustion engine is divided into a plurality of sub-streams and guided in cooling channels 23, 24 along the outer wall of the combustion chambers 25, 26 in the cylinder head 12 a, where the partial flows back to a

Connect outlet 27, which leaves the engine 1 1 via the output 28. The subsequent to the output 28 line section 29 returns the coolant to the heat exchanger 15, where it emits the heat absorbed in the engine 11 to the environment.

In the thermally particularly stressed sections in the interior of the internal combustion engine, in particular in the regions 23, 24 surrounding the combustion chambers, the inner walls of the coolant lines or channels are provided with the microstructured surface according to the invention.

In addition, the internal combustion engine 11 shown in FIG. 1 has an exhaust gas recirculation system designated overall by the reference numeral 30, which contains an exhaust gas cooler 31. Air is drawn into the combustion chambers 25, 26 of the internal combustion engine 1 1 via an intake line 32. The resulting after the combustion of the fuel exhaust gas is discharged via an exhaust pipe 33. Via a valve-controlled branch 34, a partial flow of the exhaust gas via an exhaust gas recirculation line 35, 36 is returned to the intake manifold 32, so that the excess of oxygen in the combustion chambers is reduced and the combustion temperature is reduced, resulting in a reduction of NO _x pollution of the exhaust gases and a lower fuel consumption leads. By cooling the recirculated exhaust gases, these effects can be amplified. For this purpose, an exhaust gas cooler 31 is arranged in the exhaust gas recirculation line 35, 36, which cools the hot exhaust gases. The exhaust gas cooler 31 may have a separate cooling circuit. In the illustrated embodiment, however, a partial flow of the cooling circuit 13 is passed to a valve-controlled branch 37 via a line 38 in the exhaust gas cooler 31. The heated coolant is then returned via a line 39 into the cooling circuit 13. The exhaust gas cooler 31 may be formed, for example, as a tube bundle heat exchanger, wherein the exhaust gas stream is divided into individual tubes 40, which are surrounded by the coolant 41. The outer shells of the tubes 40 are provided with the microstructured surface layer according to the invention. For further, known to those skilled in the features of the cooling circuits of modern internal combustion engines, such as pressure devices, secondary heat exchangers, which are in thermal contact with the heating system of the passenger compartment, etc, was omitted in the schematic representation of FIG. 1 for reasons of clarity.

Comparative tests:

To verify the effectiveness of the microstructured surface layer provided according to the invention, conventional cast iron cast casings (cast iron with 3.5% C, 2.0% Si, 0.7% Mn and 0.5% phosphorus as the essential alloying elements) with unprocessed cast skin were used Siedeprüfstand compared with a similar casting sleeve, in which a microstructured surface layer according to the invention was applied to the casting skin. For this purpose, by metal spraying with compressed air, a porous layer of an iron alloy (Cr. Ca.29%, Ni about 6%, B about 3% remainder: iron) with a layer thickness of about 200-400 microns applied. The current for melting the iron wires was about 150 A at about 40 volts. The molten metal was distributed with approximately 4 bar compressed air on the surface of the boiling sleeve. The approx. 4 cm long sleeve with a

Diameter of about 1 cm was finished coated after about 10 seconds coating time.

In a Siedeprüfstand the effectiveness of the heat transfer depending on temperature, cooling medium used and flow velocity was determined by means of so-called boiling characteristics. Boiling curves describe the relationship between the transmitted heat flow per area (heat flow density) and the wall temperature or the difference between the wall temperature and saturation temperature of the liquid (the so-called wall overheating T _w -T T _sat ) in one or two-phase heat transfer.

For carried out with the coated casting sleeve measurements sold commercially by the assignee of coolants "Glysantin ^® Alu Protect" was used without defoamer. For a comparative experiment with uncoated cast sleeve was also commercially marketed by the Applicant

Coolant "Glysantin ^® Protect Plus" used. In all the cases considered, the system pressure was p _sys = 3.2 bar absolute, and the temperature of the cooling medium was kept constant at T _sys = 100 ° C.

The typical course of boiling characteristics can be described as follows: at wall temperatures below the saturation temperature and at lower temperatures Wall overheating is the heat transfer by free, single-phase convection, which leads to better heat transfer coefficients with increasing temperature difference and thus to a slight increase in the boiling curve. Depending on the wettability of the wall arise after a more or less severe bumping first vapor bubbles at certain points of the wall surface, the number and size grows with increasing wall overheating. After detachment of the first bubbles from the contact surface, the so-called nucleate boiling begins. The contact surface is still completely wetted by the liquid in this area. Due to the increased steam production and the intensive stirring effect of coalescing vapor bubbles, the heat flux increases steeply.

1. aging behavior

The first investigation concerned the aging behavior of the surface and the associated changes in the boiling heat transfer.

For this purpose, several boiling characteristics were recorded within a time interval of 28 h at a mean flow velocity U _b = 0.25 m / s.

The result of the experiment is shown in FIG.

It is clear from the boiling characteristics recorded in this time interval that virtually no aging, i. E. no deterioration in the boiling behavior can be determined, since the individual boiling characteristics with different aging states practically coincide with one another.

2. Comparison of coated and uncoated cast sleeve

In the diagram of Figure 3, the boiling behavior of the uncoated casting sleeve using "Glysantin ^® Protect Plus" is (curve A1 in Fig. 3) and "Glysantin ^® Alu Protect" (curve A2) as a refrigerant to that of the coated casting sleeve using "Glysantin ^® AIu Protect" (curve B1) compared as a coolant. All boiling characteristics considered here have the same state of aging. The comparison is again carried out for the case of the average flow velocity of U _b = 0.25m / s.

From Figure 3, the improved boiling heat transfer of the cast sleeve with a porous surface over that of the standard cast sleeve is clearly visible. This improvement in the boiling heat transfer is reflected at high heat flux densities (~ 400,000 W / m ² ) in a reduction of the surface temperature T _w over the standard cast sleeve by an amount of ΔT _W = 15 to 20 ° C. A closer look at the Temperature range in which the boiling sets in, shows that in the modified cast sleeve with a porous surface, the boiling already at a wall temperature T _w <T _sat sets (deviation of the boiling curve of the linearity).

3. Variation of the flow velocity

In the diagram of FIG. 4, boiling characteristics of the uncoated (family of curves Ai) and of the coated casting sleeve (family of curves Bi) are shown at different mean flow velocities u _b .

In all cases shown, the temperature of the cooling medium T _sys = 100 ° C and the absolute system pressure p _sys = 3.2 bar. "Glysantin ^® Alu Protect" were respectively used as the cooling medium. The indices i of the family of curves Ai and Bi respectively denote flow velocities Ub of 0.1 m / s (i = 1),

0.25 m / s (i = 2), 0.5 m / s (i = 3), 0.75 m / s (i = 4), 1.0 m / s (i = 5) and 1.5 m / s (i = 6).

For all cases considered, the significant improvement of both the single-phase and the two-phase heat transfer when using the modified cast sleeve with a porous surface compared to the uncoated cast sleeve recognizable.

In summary, it can be stated as the result of the comparative experiments:

It is clear from the boiling characteristics recorded with the modified cast sleeve that virtually no aging of the surface, i. no deterioration in the boiling behavior is detectable.

• Due to the greater surface roughness, a significant improvement in the single-phase heat transfer was observed when using the test specimen with a porous surface compared to the standard sleeve.

• Both the boiling efficiency and the boiling activity could be significantly increased when using the porous surface compared to the standard surface with untreated casting skin. As a result, the surface temperature at high heat fluxes could be reduced by about 15 ° C.

Claims

claims

An apparatus for cooling an internal combustion engine (1 1) with a cooling circuit (13) comprising at least one cooling channel (23,24,41) for a liquid coolant, which with at least one component (12a, 12b, 31) of the

Internal combustion engine (1 1) is in thermal contact, characterized in that a coming into contact with the coolant wall of the cooling channel (23,24,41) has a microstructured surface at least in a partial region.

2. Device according to claim 1, characterized in that the microstructured surface has an average surface roughness Ra in the range of 1 to 1500 microns.

3. Device according to one of claims 1 or 2, characterized in that the microstructured surface has a porous structure.

4. The device according to claim 3, characterized in that the average size of the pores of the microstructured surface in the range of 1 to 500 microns.

5. Device according to one of claims 3 or 4, characterized in that the pore content is in the range of 1 to 90%.

6. Device according to one of claims 3 to 5, characterized in that the microstructured surface having a porous structure has a layer thickness of 1 to 10,000 microns.

7. Device according to one of claims 3 to 6, characterized in that the structures of the microstructured surface are arranged regularly.

8. Device according to one of claims 3 to 6, characterized in that the structures of the microstructured surface are arranged stochastically.

9. Device according to one of claims 1 to 8, characterized in that at least the thermally highly stressed during operation sections of the wall or the walls of the cooling channel having the microstructured surfaces.

10. Device according to one of claims 1 to 9, characterized in that with at least one cooling channel (23,24,41) in thermal contact Component of the internal combustion engine (1 1) is a cylinder head (12 a) and / or a crankcase (12 b) of the internal combustion engine and / or an exhaust gas cooler (31).

1 1. A device according to any one of claims 1 to 10, characterized in that an aqueous coolant circulates in the cooling circuit, which contains surface-active additives, in particular surfactants.

12. A method for producing a device for cooling an internal combustion engine, wherein a cooling circuit for a liquid

Forms coolant having cooling channels, which are at least partially in thermal contact with the internal combustion engine, wherein at least on a part of the coming into contact with the liquid coolant walls of the cooling channels generates a microstructured surface.

13. The method according to claim 12, wherein the microstructured surface produced by mechanical and / or chemical processing of the walls.

14. The method of claim 12, wherein the microstructured surface is formed by applying or depositing a coating material on the walls.

15. The method according to claim 12, wherein the microstructured surface is produced during casting of the internal combustion engine.