Patent Application
20070144498
The present application relates to apparatus and methods for cooling devices and, more particularly, to apparatus and methods for cooling devices using cooling fluids at low flow rates.
Electronic control modules (ECMs) are used to control electronic fuel injector systems of modem diesel engines. They enable the diesel engines to meet modem pollution standards while enhancing ease of starting, driveability and performance.
Normal operation of an ECM causes a certain amount of heat to be generated by the electronics within the ECM. In some circumstances the generated heat may be dissipated to the air surrounding the ECM. However, oftentimes the ECM is placed in a relatively hot area (e.g., near the engine) or in a location where heat is not easily dissipated, thereby requiring auxiliary cooling.
Liquid coolers have been attached to or included within ECMs to remove the extra heat by circulating various cooling fluids over or through the ECMs. The cooling fluids may be diesel fuel, engine coolant or the like.
One type of diesel fuel cooling/plumbing system utilizes two fluid lines: one line from the fuel tank to the engine and one line from the engine back to the fuel tank. Such systems have the advantage of utilizing high fluid flow rates (i.e., they pass more fuel through the fluid lines than the engine consumes), thereby producing fluid convection behavior that is capable of cooling the ECM without special shapes being as important.
An alternative diesel fuel cooling system utilizes a single fluid line (i.e., one line from the fuel tank to the engine). Such systems operate at much lower fluid flow rates (i.e., typically low-speed laminar flow) and therefore offer less efficient heat transfer.
Specifically, such systems operate at fluid flow rates corresponding to the rate of fuel consumption by the engine (e.g., about 0.25 to about 1.5 liters per minute).
Accordingly, there is a need for an apparatus and method for efficiently cooling various devices (e.g., ECMs) using cooling fluids at low flow rates.
In one aspect, a cooling apparatus includes an elongated body portion having a fluid inlet, a fluid outlet and a fluid channel extending between the fluid inlet and the fluid outlet, wherein the fluid channel includes at least one of a generally G-shaped cross-section, a generally ( )-shaped cross-section and a generally C-shaped cross-section.
In another aspect, a cooling system includes a heated substrate and a cooling unit connected to the heated substrate, wherein the cooling unit includes an elongated body portion having a fluid inlet, a fluid outlet and a fluid channel extending between the fluid inlet and the fluid outlet, wherein the fluid channel includes at least one of a generally G-shaped cross-section, a generally ( )-shaped cross-section and a generally C-shaped cross-section, and a cooling fluid adapted to move through the fluid channel to cool the heated substrate.
In another aspect, a method for cooling a heated substrate includes the steps of providing a cooling unit having an elongated fluid channel extending therethrough, wherein the fluid channel includes at least one of a generally G-shaped cross-section, a generally ( )-shaped cross-section and a generally C-shaped cross-section, contacting the cooling unit to a substrate and passing a cooling fluid through the fluid channel to cool the substrate.
Other aspects of the cooling apparatus and method will become apparent from the following description, the accompanying drawings and the appended claims.
As shown in
In another aspect, the fluid inlet 16 may be in fluid communication with a fluid source (not shown) such as a fuel tank and the fluid outlet 18 may be in fluid communication with the combustion chamber of an engine (not shown) such that fluid exiting the cooling unit 10 by way of the fluid outlet 18 is passed directly to the engine as fuel. Therefore, the cooling fluid may move though the channel 14 at a relatively low flow rate. In one aspect, the fluid flow rate through the channel 14 may be related to the rate that fuel is consumed by the engine (e.g., about 0.25 to about 1.5 liters per minute).
In another aspect, the unit 10 may be formed from aluminum. However, those skilled in the art will appreciate that the unit 10 may be constructed from various materials (including metals and non-metals) capable of conducting thermal energy without reacting with the cooling fluid. In one aspect, the body 12 and channel 14 may be shaped and formed by an aluminum extruding process.
The cooling unit 10 may be provided with an attachment mechanism for securing the cooling unit 10 to a device requiring cooling. For example, as shown in
As shown in
In one aspect, the channel 14 may have an overall cross-sectional diameter D of about 10 to about 40 millimeters and the channel 14 may have a cross-sectional thickness T of about 1 to about 30 millimeters. The generally G-shaped or generally C-shaped channels may be one continuous channel in cross-section or two or more separate channels in cross-section. The generally ( )-shaped channel may be two or more separated channels in cross-section.
Without being limited to any particular theory, it is believed that the “G,” “C” and “( )” shaped channels offer improved heat transfer at low, laminar flow rates due to the low thermal resistance and reduced back pressure achieved by the “G,” “C” and “( )” geometries. In particular, it is believed that the “G,” “C” and “( )” geometries minimize thermal resistance by maximizing the internal surface area (i.e., the flux area) of the channel 14 while minimizing the boundary layer thickness (i.e., the flow gap width) of the unit 10. Furthermore, it is believed that the “G,” “C” and “( )” geometries minimize backpressure by maximizing the cross-sectional flow area of the unit 10, while eliminating sharp corners and intersections.
Two cooling units were prepared as described above using an aluminum extruding process. Each unit was approximately 0.22 meters long. The first unit incorporated a channel having a G-shaped geometry and the second unit incorporated a channel having a ( )-shaped geometry. Each channel had a thickness of about 1.52 mm and an overall diameter of about 14.5 mm. The thermal resistance and backpressure of each unit was determined at various flow rates using mineral oil as the cooling fluid to safely simulate #2 diesel fuel. The results are set forth in Table 1 for the G-shaped channel and Table 2 for the ( )-shaped channel.
Accordingly, cooling units having generally G-shaped and generally ( )-shaped cross-sectional geometries may provide improved heat transfer at low, laminar flow rates.
Although the cooling apparatuses and methods are shown and described with respect to certain aspects, modifications may occur to those skilled in the art upon reading the specification. The cooling apparatuses and methods are limited only by the scope of the claims.
