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  Heat exchangerRelated Patent Categories: Heat Exchange, Flow Passages For Two Confined FluidsHeat exchanger description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20070068663, Heat exchanger. Brief Patent Description - Full Patent Description - Patent Application Claims
[0001] This application claims priority from International Patent Application No. PCT/EP2005/010303 filed Sep. 23, 2005, and from German Patent Application No. 20 2006 009 464.4, filed Jun. 16, 2006. The entire disclosures of the above patent applications are hereby incorporated by reference. FIELD OF THE INVENTION [0002] The invention relates to a heat exchanger with a channel through which cooling agent flows and a channel through which fluid to be cooled flows, which channels are separated from one another by at least one wall from which issue ribs extending into at least one of the two channels. BACKGROUND OF THE INVENTION [0003] Such heat exchangers are generally known and are described in a number of Applications. There exist heat exchangers in which the ribs project only into the channel conducting cooling agent as well as heat exchangers whose ribs project into the channel through which the fluid to be cooled flows and heat exchangers with ribs pointing in both directions. These ribs distinctly improve the heat transfer between the two fluids. In particular, the ribs increase the residence time and the dynamic pressure in the corresponding channel in comparison with embodiments without ribs. In a heat exchanger used as an exhaust gas heat exchanger in internal combustion engines, such ribs can also be used in order to prevent to the greatest extent possible, a sooting or carbon fouling of the channel through which the exhaust gas flows. [0004] Thus in DE 10 2004 045 923 A1 heat exchangers are described whose ribs are shaped in different ways. They project from two inner walls bordering the channel into the channel conducting the fluid to be cooled. All these ribs feature an axially symmetrical shape and are installed at an angle to the main flow direction, at least over a section. Both the approach area and the flow-off area of these ribs are embodied with a radius. [0005] The disadvantage of the above-mentioned embodiments is that the manufacturing cost is relatively high, since both inner walls must be embodied with ribs and secondly a high pressure drop is present due to the relatively large dynamic pressure zone as the rib is approached. [0006] An improved efficiency is achieved through the plate heat exchanger known from U.S. Pat. No. 2,892,618, whose ribs feature side walls arranged concave to one another, each with an approach edge and a flow-off edge. [0007] From GB 892 534 a heat exchanger is known that features ribs with a straight side wall and a concave side wall. As a result of the linear approach edge, the dynamic pressure zone of the flow as it approaches the rib, in which the speed is reduced to zero, is minimized, so that a lower pressure drop is achieved. Moreover the continuously running side walls cause the formation of a boundary layer that is adjacent in the area of the rib, so that heat can be exchanged over a lengthened cooling zone. [0008] In all the above-mentioned embodiments, however, a relatively high susceptibility of the heat exchanger to sooting arises, in particular during use as an exhaust gas heat exchanger. The efficiency is also limited by a lack of mixing of the fluid to be cooled. [0009] The object of the invention is therefore to develop a heat exchanger whose ribs are optimized with respect to the flow, so that the efficiency of the heat exchanger is increased by raising the heat transfer at the ribs, whereby at the same time the pressure drop in the heat exchanger is to remain as low as possible. Moreover it is desirable to achieve the lowest possible sooting of the ribs, and homogeneity of the fluid to be cooled. SUMMARY OF THE INVENTION [0010] This object is achieved in that each rib features one linear approach edge and two linear flow-off edges, whereby the approach edge and the two flow-off edges delimit two continuously running side walls of the rib. Thus the pressure drop is minimized by means of the single approach edge and boundary layer flows are created along the entire length of the rib due to the continuous course of the side walls, and a separation of the boundary layer flows is prevented, so that the heat transfer is improved. Due to the two flow-off edges, compared with known embodiments a distinctly improved intensive mixing transverse to the flow direction is achieved, so that the homogeneity of the fluid stream is increased, which in turn results in a temperature exchange and temperature equilibrium of the entire mass flow. All this increases the efficiency of the heat exchanger. [0011] In a preferred embodiment, the ribs extend along the main flow direction, as a result of which the pressure drop is minimized and it is ensured that the boundary layer will be adjacent on both sides of the rib. A low pressure drop is particularly advantageous when the heat exchanger is used as an exhaust gas heat exchanger in the low-pressure zone of an internal combustion engine, since in such a use the pressure drop present is very low. [0012] In a further form of embodiment of the invention, the side walls of each rib adjacent to the approach edge and the flow-off edge enclose an angle to one another that is less than or equal to 90.degree.. This ensures that the pressure drop is sufficiently small and undesired turbulence and separation along the cooling zone of each rib are avoided. [0013] In order to ensure that a boundary layer flow first forms behind the dynamic pressure point, i.e. behind the approach edge, in a front area the side walls extending from the approach edge of each rib are arranged with respect to one another essentially wedge-shaped. [0014] In an advantageous alternative embodiment, in a front area the angle between tangents to the two side walls decreases continuously in the main flow direction until the side walls run parallel to one another in a back area. This, too, leads to an increase in the efficiency, since a separation of the boundary layers over the course of the rib is avoided in this manner and a sufficiently long cooling zone is available at the rib. [0015] In a further form of embodiment of the heat exchanger, the ribs are arranged in rows adjacent to one another perpendicular to the main flow direction, whereby the ribs of each row are arranged staggered with respect to the following row. This prolongs the residence time of the fluid flowing through the channel and thus in turn raises the efficiency of the heat exchanger, since a smooth flow-through of the heat exchanger is avoided to the greatest possible extent. Moreover the flow-through speed is raised due to the small cross-sections available for the flow such that a turbulent flow around the ribs is ensured, as a result of which a high wall shearing stress and thus a higher heat transfer factor a is achieved, so that an increase in the cooling performance is ensured by raising the heat convection. [0016] Advantageously a heat exchanger of this type is used as an exhaust gas heat exchanger whose ribs project into the channel conducting exhaust gas. This is particularly advantageous, since a carbon fouling due to the flow speeds and turbulence arising is reliably avoided, whereby at the same time a high efficiency and thus a low necessary size are achieved, which is particularly important in automobile manufacture based on the small space available. [0017] Thus in comparison with the known prior art, a heat exchanger is created that requires a smaller space due to an increase in the efficiency, and is not susceptible to sooting. At the same time it can be produced cost-effectively using the die-casting process. The fluid to be cooled leaves the heat exchanger in a well-homogenized state. [0018] An embodiment of the heat exchanger according to the invention is shown in the Figures and is described below. BRIEF DESCRIPTION OF THE DRAWINGS [0019] FIG. 1 shows a top view of a heat exchanger according to the invention in sectional view. [0020] FIG. 2 shows a head-on view of the heat exchanger from FIG. 1 in sectional view. Continue reading about Heat exchanger... Full patent description for Heat exchanger Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Heat exchanger patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Heat exchanger or other areas of interest. ### Previous Patent Application: Heat exchanger Next Patent Application: Method of manufacturing a cooling plate and a cooling plate manufactured with this method Industry Class: Heat exchange ### FreshPatents.com Support Thank you for viewing the Heat exchanger patent info. 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