KR20080087878A - Liquid cooling device in internal combustion engines and process for manufacturing same - Google Patents

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

LIQUID COOLING DEVICE IN INTERNAL COMBUSTION ENGINES AND PROCESS FOR MANUFACTURING SAME

The present invention relates to an apparatus for liquid cooling of an internal combustion engine and a process for manufacturing the apparatus.

In the operation of piston engines, such as four-stroke gasoline engines or diesel engines used in internal combustion engines such as vehicles, temperatures in excess of 2000 ° C. occur in the combustion chamber of the cylinder. The heat transferred from the cylinder to the engine block and the cylinder head via the cylinder wall is threatening to other components of the internal combustion engine with only limited thermal resistance and thus to avoid damaging these components as a result of overheating. This heat must be removed as efficiently as possible.

Cooling of internal combustion engines using air or liquid as the refrigerant is known from the prior art. Liquid cooling using water as the cooling liquid is particularly preferred in the prior art, since the large heat capacity and low viscosity of the water allows for efficient cooling of the internal combustion engine. In water-cooled internal combustion engines, cooling channels which form part of the cooling circuit through which the conveyed cooling water passes are located, for example, in the crankcase or on the cylinder head and / or the wall of the cylinder. In certain parts of the cooling circuit located outside of the internal combustion engine, there is an air cooled heat exchanger, called a radiator in the case of automobiles, and through this air cooled heat exchanger, the cooling water releases heat taken from the internal combustion engine to the surrounding environment. Cooling liquid usually enters the internal combustion engine in a region of relatively low position and is conveyed to the cylinder head through a cooling jacket or cooling channel of the engine block / crankshaft housing, and the cooling liquid is again flame retarded in the region located higher from here. Exit the organ However, before the liquid for cooling enters the engine housing, it preferably branches the cooling liquid into two separate circuits by means of an actuating valve and separates the branched streams separately from the cooling channels or cooling channels of the crankshaft housing and cylinder head. Transporting in a jacket is also known.

Additional heat exchangers, compressors and condensers may be provided in the cooling circuit which interact with the air conditioning unit or heating system of the motor vehicle. Thus, for example, the heat released by the internal combustion engine can be used to at least partially heat the passenger compartment. Cooling of hot exhaust gases from internal combustion engines by means of suitable heat exchangers is also known. At this time, the thermal energy taken from the hot exhaust gas in the start-up phase can be used, for example, to heat the liquid for cooling, so that the internal combustion engine through which the flowing liquid passes is operated more quickly and optimally. Reaches the temperature. However, cooling of the exhaust gas is particularly advantageous in the case of exhaust gas recycling systems currently used in the automotive sector to reduce consumption in the partial load region and then to reduce emissions from internal combustion engines, in particular NOx. At this time, the substream of exhaust gas, which can usually be controlled by a valve, is recycled to the intake of the internal combustion engine. In addition, the effect of the recycle of exhaust gas on the consumption and reduction of NOx emissions can be further improved when the substream of recycled exhaust gas is cooled by the exhaust gas cooler.

The circulation of the cooling liquid is usually done by a pump located in a cooling circuit driven directly by the internal combustion engine via the V belt, thereby producing a cooling liquid flow which depends on engine rotation. It is also known to bypass the cooler by a thermostat-controlled valve in the heat-up phase of the internal combustion engine so that the internal combustion engine can quickly reach the optimum operating temperature of the internal combustion engine. .

In addition to the absorption of heat generated in the internal combustion engine by heating the cooling liquid, partial vaporization of the cooling liquid occurs in particular in the high temperature region, whereby a very effective cooling of the corresponding engine surface can be achieved by the corresponding vaporization enthalpy. have.

Nowadays, modern internal combustion engines no longer use only water as a cooling liquid, but instead use a liquid, usually called a refrigerant, with a liquid containing additional additives, especially additives that serve to prevent freezing and corrosion. .

Refrigerant compositions in the cooling circuits of internal combustion engines as used in motor vehicles include, usually with water, alkylene glycols which are mainly ethylene glycol and / or propylene glycol and / or glycerol as antifreeze components.

For example, the use of higher order glycols and glycol ethers as well as alkylene glycols as antifreezing components is known from EP-A-816467.

Since the components of the internal combustion engine undergo large thermal stresses as a result of the dominant absolute temperature during operation and also as a result of temperature fluctuations, any type and any level of corrosion can lead to a shortening of the operating life of the internal combustion engine and an internal combustion engine. It is also a potential risk factor that can lead to a decrease in reliability. Many of the materials used in modern internal combustion engines, such as cast iron, copper, brass, wax, steel, and light metal alloys, in particular magnesium alloys and aluminum alloys, present additional potential corrosion problems, particularly at locations where different metals are in contact with each other. cause. Various types of corrosion, such as pit corrosion, steel corrosion, erosion, or cavitation, can occur particularly easily at these locations. Thus, modern refrigerant compositions also include certain corrosion inhibitors that serve as corrosion protection components. DE-A 195 474 49, EP-A 0 552 988 or US-A 4,561,990 disclose cryoprotectants comprising carboxylic acids, molybdates, or triazoles, for example for cooling water in internal combustion engines. EP-A 0 229 440 discloses a corrosion protection component comprising aliphatic monobasic acid, dibasic hydrocarbon acid, and hydrocarbon triazoles. Specific acids as corrosion protection components are described for example in EP-A 0 479 470. Quaternized imidazoles as corrosion protection components are known from DE-A 196 05 509. The refrigerant composition must also be suitable for non-metallic components of the cooling circuit, such as hose connections or other plastics and elastomers as seals and to not alter or corrode these components.

Besides the steady improvement in the freeze protection component and the corrosion protection component of the refrigerant composition, the latest technology development aims at improving the cooling characteristics of the cooling liquid, in particular. Therefore, it has been proposed to improve the cooling properties, for example by additives which reduce the viscosity and / or flow resistance of the cooling liquid in the cooling circuit.

The power density that can be achieved by an internal combustion engine is critically influenced by the efficiency of liquid cooling. It is therefore an object of the present invention to provide a liquid cooling device of an internal combustion engine, in particular of an internal combustion engine using the above-mentioned liquid refrigerant, wherein the cooling action is further improved at the surface of the internal combustion engine which is particularly exposed to large thermal stresses. The invention also relates to a process for making such a device.

This object is achieved by a liquid cooling device of an internal combustion engine having the features of claim 1 herein. Advantageous embodiments of the device according to the invention are the subject of the dependent claims.

The present invention thus provides an internal combustion engine cooling apparatus consisting of a cooling circuit comprising at least one cooling channel for a liquid refrigerant in thermal contact with at least one component of the internal combustion engine, wherein the wall of the cooling channel is brought into contact with the refrigerant. Has at least a microstructured surface in the subregion. When referring to the liquid refrigerant in the present invention, the liquid refrigerant refers to the state of the refrigerant material at a temperature of 0 to 100 ° C. and atmospheric pressure. Depending on the freeze protection component used, the refrigerant may also be liquid at lower or higher temperatures.

In cooling circuits known from the prior art for internal combustion engines, attempts have been made to make the surface of the cooling circuit line as smooth as possible in normal contact with the liquid refrigerant as much as possible in order to minimize the flow resistance of the refrigerant. It has been found that even better cooling action can be achieved by the cooling device modified according to the present invention without giving. In particular, the microstructured surface of the cooling device according to the invention improves single phase heat transfer before the initiation of the boiling of the refrigerant, and also provides two-phase heat transfer, in particular rapid boiling and bubble boiling sections of the refrigerant. It has also been found to significantly improve boiling in. Thus, for example, the temperature difference between the superheat of the wall, ie the wall temperature T _w at the bubble boiling start point and the saturation temperature T _s of the refrigerant, is about 3 to 10 in the range of about 20 to 40 ° C. It has been found that it can be reduced in the range of ° C.

Thus, the device of the present invention for liquid cooling of an internal combustion engine makes it possible to achieve a decisive improvement in the cooling of an internal combustion engine. As described above, the power density of modern internal combustion engines is mainly limited by the efficiency of heat removal by cooling, so that the apparatus of the present invention also makes it possible to increase the power density of internal combustion engines.

The various components of the internal combustion engine can be cooled by cooling channels having a microstructured surface provided according to the present invention. Above all, the cooling channel is in thermal contact with the components of the engine block of the internal combustion engine, such as the cylinder head and / or the crankcase. However, as used in connection with the present invention, the term "component of an internal combustion engine" also refers to an additional heat exchanger such as an exhaust gas cooler or an oil cooler located in a component outside the actual engine block, in particular in the cooling system of the internal combustion engine. It includes. These heat exchangers each have a separate cooling liquid circuit, but particularly preferably in a situation where the cooling liquid stream divided into individual small parts can be controlled by an appropriate valve, which mediates the sub-circuits of the cooling circuit of the internal combustion engine. It is preferable to cool these heat exchangers.

In 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 μm, preferably in the range from 20 to 200 μm.

The microstructured surface particularly preferably has a porous structure. The size of the pores of the porous microstructure is advantageously in the range from 1 to 500 μm. The pore size then relates to the maximum pore diameter in the cross section. The voids can, for example, have a substantially round cross section, but any other void shape is likewise possible. The proportion of voids in the microstructured surface layer may range from 1 to 90%, preferably from 10 to 80%, most preferably from 10 to 70%.

The coarse and / or porous microstructures of the device according to the invention may be distributed regularly or disorderly over the surface. The preferred pore depth when the pores are arranged randomly corresponds approximately to the diameter of the pore. Especially in the case of machining voids on the surface, it can vary from rounded void shapes to arbitrary geometric shapes, eg longitudinal channels with different profiles. The depth of the void or channel or other depressions depends on the width of the void. The depth of the microstructured surface layer is preferably in the range of several microns to several millimeters, for example in the range of 1 to 10,000 μm, preferably of 10 to 1000 μm.

In one variant of the device according to the invention, the entire wall surface of the lines and channels of the cooling circuit which come into contact with the liquid refrigerant can be configured as a microstructured surface. In a preferred variant, however, the microstructured surface is a region of the cooling circuit located in an area which is cooled in any heat exchanger for cooling the hot gas disposed in the internal combustion engine and / or the cooling circuit, such as the exhaust gas cooler described above. Limited to.

As the liquid refrigerant, preference is given to using the aforementioned water based refrigerant composition comprising alkylene glycols. In a preferred variant of the device according to the invention, the refrigerant may comprise surface active additives, such as surfactants, which reduce the surface tension of the refrigerant. These surface active additives further aid the boiling process by further lowering the superheat of the walls required for initiation of bubble boiling.

The cooling circuits of modern internal combustion engines are usually operated at absolute pressures of 1.5 to 5 bar in order to increase the saturation temperature of the liquid refrigerant and thus further improve the cooling action.

The invention also provides a manufacturing process for producing the device of the invention for liquid cooling of an internal combustion engine. According to the present invention there is provided a cooling circuit for a liquid refrigerant having a cooling channel at least partially in thermal contact with an internal combustion engine, wherein the microstructured surface is formed in at least a portion of the wall of the cooling channel in contact with the liquid refrigerant. Is formed.

Since manufacturing processes for manufacturing cooling circuits for internal combustion engines, in particular automotive engines, are known to those skilled in the art, the following information may be limited to the formation of the microstructured surface provided in accordance with the present invention. The inner wall of the cooling channel in which the microstructured surface is formed preferably comprises a material, in particular a metal, having good thermal conductivity. Such a channel is particularly preferably formed during the casting of an internal combustion engine, so that the channel wall is usually made of the same material as the engine block, cylinder head cover, or crankcase.

In a first variant of the manufacturing process according to the invention, the microstructured surface is formed by mechanical treatment of the inner wall of the cooling channel. For example, suitable microstructures can be formed by cutting the walls, for example by milling grooves and other depressions, or by embossing the structure with rollers or plates of appropriate profiles. In addition, suitable microstructured coatings that can be used in the apparatus of the invention are known, for example, from chemical treatment techniques. Thus, for example, Viland-Berke AG, a company in Ulm, Germany, manufactures heat exchanger tubes under the name "enhanced boiling tubes". Here, the microstructures mechanically formed by the targeted manner serve to improve heat transfer during vaporization. Suitable mechanical methods for forming 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 walls that are exposed to large thermal stresses can be done, for example, by polishing the walls, for example by striking hard with sand, metal spheres, or ceramic spheres, or other abrasive particles. In addition, the microstructured surface layer may be formed by chemical treatment of the wall, for example by etching of the wall with a suitable acid or base.

In a further variant of the manufacturing process according to the invention, the microstructured surface is formed by depositing a rough layer and / or a porous layer on the surface to be treated. The microstructured surface may in this case also comprise a material different from the material of the inner wall of the cooling channel. A wide range of processes known from coating techniques can be employed, such as flame spraying, PVD processes or CVD processes, powder coating or plasma coating, sputtering or various spraying or atomizing processes. In addition, coatings, such as those known from known tubes with a porous coating, available under the name "high-flux tubes" from UF LLC, Des Plaines, Ill., Can be used. At this time, the improvement of heat transfer during vaporization is achieved by disorderly distributed pores. The process for producing such porous layers by applying zinc plating of porous foams and subsequent foams is described in US Pat. No. 4,136,427. Other methods of making suitable layers are described, for example, in JP-A 2001-038463 or FR-A 0 112 782, in which the metal particles having the appropriate particle size are connected to each other by a brazing material to form a porous surface layer. do. It is also possible to mix additives with the refrigerant which thermally decompose and thus form a degradation product which is deposited as a porous coating on the cooling surface.

In a particularly preferred variant of the process according to the invention, the microstructured surface is formed directly during the casting of the internal combustion engine. At this time, the casting mold may be provided with an appropriate microstructure. However, particularly briefly, before casting the engine block to the high spaces of the engine block, the surface of the body formed into slips or slurries of metal and / or ceramic particles of suitable particle size and polymers that degrade during casting It is also possible to coat on.

The invention is explained below by means of examples schematically illustrated in the accompanying drawings and by comparative experiments conducted in boiling rigs.

1 is a schematic diagram of a liquid cooling apparatus of an internal combustion engine.

FIG. 2 shows a boiling line showing the aging behavior of a casting tube with a microstructured surface according to the invention.

3 shows the boiling curves of casting tubes and modified casting tubes according to the invention in a comparative experiment.

4 shows the boiling curves of casting tubes and modified casting tubes according to the invention at different flow rates for further comparative experiments.

1 is a schematic illustration of an apparatus 10 according to the invention for liquid cooling of an internal combustion engine 11. In the example shown, the internal combustion engine 11 is configured as an automobile engine with an engine block 12b with a crank chamber and a cylinder head 12a. The vehicle engine 11 is cooled by a refrigerant circulating in the cooling circuit 13. The cooling circuit 13 has a pump 14 and an external air-cooled main heat exchanger 15, commonly referred to as a "radiator" in the case of motor vehicles. The thermostat valve 17, controlled by the temperature sensor 16, is located upstream of the inlet of the radiator 15, and in accordance with the operating conditions of the internal combustion engine, a long circuit in which the refrigerant stream extends through the heat exchanger 15 ( 18) or short circuit 19 bypassing the heat exchanger 15.

The refrigerant stream coming from the main heat exchanger 15 enters the vehicle engine 11 through the cooling liquid inlet 20 located in the region of the crank chamber 12b. Depending on the number of cylinders in the engine, the refrigerant stream is divided into a plurality of substreams in the internal combustion engine, which substreams the cylinder head 12a in the cooling channels 23, 24 along the outer walls of the combustion chambers 25, 26. The substream is conveyed back to the outlet line 27, which is merged again at the cylinder head and exits the motor vehicle 11 via the outlet 28. The outlet portion 28 and the adjacent line portion 29 direct the refrigerant back to the heat exchanger 15 which releases the heat taken from the motor vehicle 11 to the surrounding environment.

Particularly exposed to large thermal stresses in the interior of an automobile engine, specifically in the areas 23 and 24 surrounding the combustion chamber, the inner wall of the refrigerant line or channel is provided with a microstructured surface according to the invention. .

In addition, the internal combustion engine 11 shown in FIG. 1 is provided with an exhaust gas recirculation facility, which is generally designated 30 and includes an exhaust gas cooler 31. Air enters the combustion chambers 25, 26 of the internal combustion engine 11 via the suction line 32. The exhaust gas produced after combustion of the fuel is discharged through the exhaust gas line 33. The substream of exhaust gas branches from the valve controlled branch point 34 and is conveyed through the exhaust gas return lines 35 and 36 to the intake line 32, thereby reducing excess oxygen in the combustion chamber and lowering the combustion temperature so that the exhaust gas is reduced. To reduce the NOx load and reduce fuel consumption. This effect can be enhanced by cooling the recycled exhaust gas. For this purpose, an exhaust gas cooler 31 for cooling the hot exhaust gas is located in the exhaust gas return lines 35 and 36. The exhaust gas cooler 31 may be provided with a separate cooling circuit. However, in the illustrated embodiment, the substream of the cooling circuit 13 is branched at the valve controlled branch point 37 and conveyed to the exhaust gas cooler 31 via the predetermined line 38. The heated refrigerant is subsequently recycled to the cooling circuit 13 via the predetermined line 39. The exhaust gas cooler 31 may be configured as a shell-and-tube heat exchanger, for example, in which the exhaust gas stream is divided into one of the individual tubes 40 in which the refrigerant 41 flows around. . The outer wall of the tube 40 is provided with a surface layer of microstructure according to the present invention.

Other features of the cooling circuits of modern automotive engines known per se to those skilled in the art, such as pressure devices, auxiliary heat exchangers in thermal contact with the heating system of the cabin, and the like, have been omitted from the schematic diagram of FIG. 1 for reasons of clarity.

Comparative experiment

To test the effectiveness of the microstructured surface layer prepared in accordance with the present invention, gray cast iron (cast iron comprising 3.5% C as the main alloying element, 2.0% Si, 0.7% Mn, and 0.5% phosphorus) was used. Conventional casting tubes with fabricated and untreated casting skins were compared in boiling test rigs with similar casting tubes in which microstructured surface layers were applied to the casting skins according to the present invention. For this purpose, the porous layer of the iron alloy (about 29% Cr, about 6% Ni, about 3% B, the remainder iron) has a layer thickness of about 200 to 400 μm by metal spraying with compressed air Was applied. The current for melting the iron wire was about 150 A at about 40 V. The molten metal was distributed by about 4 bar of compressed air over the surface of the boiling tube. Coating of the tube about 1 cm in diameter and greater than 4 cm in length was terminated after a coating time of about 10 seconds.

The effectiveness of heat transfer was determined by the boiling curve in the boiling test rig as a function of temperature, cooling medium used and flow rate. The boiling curve for single-phase or two-phase heat transfer is based on the relationship between the heat flow (heat flux) and wall temperature transmitted per unit area or the difference between the wall temperature and the saturation temperature of the liquid (T _w -T _sat ). Known as.

For the measurements made with the coated casting tubes, a commercially available radiator protection product "Glysantin ^® Alu Protect" by the applicant was used without antifoam. For comparative experiments with uncoated cast tubes, a commercially available radiator protection product "Glysantin ^® Protect Plus" was also used by the applicant. In all cases where the test was conducted the system pressure was p _sys = 3.2 by absolute pressure and the temperature of the cooling medium was kept constant at T _sys = 100 ° C.

The typical shape of the boiling curve can be explained as follows. At wall temperatures below the saturation temperature and at low superheated walls, heat transfer is achieved by natural convection in the single phase, which leads to better heat transfer efficiency as the temperature difference increases and thus a gentle rise in the boiling curve. cause. Depending on the wettability of the wall, the first vapor bubbles form at certain locations on the wall surface after some apparent boiling delay, and the number and size of these bubbles increase with increasing superheat of the wall. After the first bubble is released from the contact surface, bubble boiling begins. In this section, the contact surface is still completely wet by the liquid. As a result of the increase in vapor production and the strong stirring action of the vapor bubbles being merged, the heat flux increases rapidly.

1. Aging behavior

The first study relates to changes in the transfer of vaporization heat, which is related to the aging behavior of the surface and generally the aging behavior of the surface. For this purpose, a plurality of boiling curves were recorded over 28 hours at an average flow velocity u _b of 0.25 m / s.

The experimental results are shown in FIG.

From the boiling curves recorded over this time, it can be clearly seen that no aging effect is observed, i.e. no deterioration of boiling behavior is observed, since each boiling curve in virtually different ages coincides with a single line. .

2. Comparison of uncoated casting tube and coated casting tube

In the graph of Figure 3, the boiling behavior of the "Glysantin ^® Protect Plus" the non-casting tube being coated with (curve in Fig. 3 A1) and "Glysantin ^® Alu Protect" the casting tube (curve A2) uncoated used as a cooling medium , Compare the boiling behavior of the coated casting tube (curve B1) with "Glysantin ^® Alu Protect" as refrigerant. At this time, all the boiling curves tested had the same aging state. Compare again for the case where the medium flow rate u _b is 0.25 m / s.

The improved vaporization heat transfer of a casting tube with a porous surface as compared to the standard casting tube vaporization heat transmission can be clearly seen in FIG. 3. This improvement in vaporization heat transfer is reflected at large heat fluxes (about 400,000 W / m 2) where the surface temperature T _w is lowered by ΔT _w = 15-20 ° C. compared to standard casting tubes. More precise experiments on the temperature range at which boiling begins, show that boiling commences when the wall temperature T _w is less than T _sat (deviation from the linearity of the boiling curve) in the case of modified casting tubes with porous surfaces.

3. Fluctuations in Flow Velocity

The graph of FIG. 4 shows the boiling curves of uncoated cast tubes (set of curves Ai) and coated cast tubes (set of curves Bi) at various average flow rates u _b .

In all cases shown, the temperature T _sys of the cooling medium is 100 ° C. and the absolute pressure p _sys of the system is 3.2 bar. As the cooling medium, "Glysantin ^® Alu Protect" was used in each case. The subscript i of the set of curves (Ai or Bi) indicates the flow velocity in each case [u _b is 0.1 m / s for i = 1, u _b is 0.25 m / s for i = 2, i U _b is 0.5 m / s for = 3, u _b is 0.75 m / s for i = 4, u _b is 1.0 m / s for i = 5, and u _b is 1.5 m / s for i = 6 s.

When using modified casting tubes with porous surfaces relative to uncoated casting tubes, a clear improvement can be seen in both single phase and two phase heat transfer in all cases tested.

In summary, the results of the comparative experiments are as follows.

From the boiling curves recorded using modified cast tubes, it is clear that virtually no aging of the surface, ie deterioration of boiling behavior, is observed.

Thanks to the greater surface roughness, a clear improvement in single phase heat transfer was observed when using samples with porous surfaces compared to standard tubes.

When using porous surfaces as compared to standard surfaces with uncoated cast skins, both the ease of boiling and the effect of boiling could increase significantly. As a result, the surface temperature could be reduced by about 15 ° C when the heat flow was large.

Claims (15)

Internal combustion engine comprising a cooling circuit 13 comprising one or more cooling channels 23, 24, 41 for liquid refrigerant in thermal contact with one or more components 12a, 12b, 31 of the internal combustion engine 11. (11) As a cooling device, The wall of the cooling channel (23, 24, 41) in contact with the refrigerant has a microstructured surface at least in a subregion. The internal combustion engine cooling apparatus according to claim 1, wherein the average surface roughness Ra of the microstructured surface is in the range of 1 to 1500 μm. The internal combustion engine cooling apparatus according to claim 1 or 2, wherein the microstructured surface has a porous structure. 4. The internal combustion engine cooling apparatus according to claim 3, wherein the average size of the pores of the microstructured surface is in the range of 1 to 500 m. The internal combustion engine cooling apparatus according to claim 3 or 4, wherein the proportion of the voids is in the range of 1 to 90%. 6. The internal combustion engine cooling apparatus according to any one of claims 3 to 5, wherein the thickness of the microstructured surface layer having a porous structure is in the range of 1 to 10,000 m. The internal combustion engine cooling apparatus according to any one of claims 3 to 6, wherein the structure of the microstructured surface is regularly arranged. The internal combustion engine cooling apparatus according to any one of claims 3 to 6, wherein the structure of the microstructured surface is arranged randomly. The internal combustion engine cooling apparatus according to claim 1, wherein at least some portion of the wall (s) of the cooling channel exposed to high thermal stress during operation has a microstructured surface. 10. The component of the internal combustion engine 11 according to claim 1, which is in thermal contact with one or more cooling channels 23, 24, 41 is a cylinder head 12a of the internal combustion engine and / or. Or at least a crank chamber (12b) and / or an exhaust gas cooler (31). 11. An internal combustion engine cooling device according to any one of the preceding claims, wherein the water based refrigerant comprising surface active additives, in particular surfactants, circulates in the cooling circuit. A manufacturing process of an internal combustion engine cooling device, comprising: a cooling circuit for a liquid refrigerant having a cooling channel at least partially in thermal contact with an internal combustion engine, wherein at least a part of a wall of the cooling channel in contact with the liquid refrigerant has a microstructure. The manufacturing process of the internal combustion engine cooling apparatus by which the surface is formed. 13. The process of claim 12 wherein the microstructured surface is formed by mechanical and / or chemical treatment of the wall. The process of claim 12, wherein the microstructured surface is formed by applying or depositing a coating material on a wall. 13. The process of claim 12 wherein the microstructured surface is formed during casting of the internal combustion engine.

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