Multi-pass fluid cooler

Abstract

A cooler for fluids uses multiple internal channels to increase the time a hot fluid is contained in the cooler, thus increasing cooling efficiency, and allowing the length of the cooler to be shorter than an equivalent cooler with fewer passes. The cooler uses external and internal heat-exchanging fins to increase surface area for contact with both the fluid and the external environment. The cooler is designed around a cylindrical vessel, equipped with a set of internal baffles, forming the multiple channels. End caps, one of which contains inlet and outlet ports, are welded to the cooling vessel, increasing ability to contain pressure. The small channel size and fluid flow-path holes cut through the baffles prevent air bubbles, which would reduce cooling efficiency. Coolers with four channels are provided for higher-pressure applications and coolers with six channels are provided for lower-pressure applications. Some coolers have an air flow assembly with a fan, to direct more cooling air around the cooler vessel. An airflow assembly with a fan controlled by a thermostat on the cooler is also disclosed.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Patent Application No. 60/490221, filed Jul. 26, 2003, entitled Multi-Pass Fluid Cooler, to inventor Charles Sanders, the contents of which are incorporated by reference herein in their entirety.

FIELD OF THE INVENTION

1. Field

Embodiments relate to the field of cooling systems, and in particular to fluid coolers.

2. Related Art

FIG. 1, from U.S. Pat. No. 4,207,187, to Booth, shows a combination oil-filter and cooler. Oil flows into housing 3, though fitting 17 of end cap 9, which is screwed into housing 3. End cap 9 and filter cartridge 24 seat against O-ring 47. Oil flows through central opening 31 into filter cartridge 24 and element 25 (held in place with cap 27 and spring 35). Oil flows out of end cap 13 (though fitting 19) in direction 6. Cylinder 3 includes outer fins 5 and inner fins 7, to facilitate heat conduction.

The Booth cooler requires a filter, which is no longer a requirement for many modern coolers, because the machinery to which they will be attached already contains sufficient filtering. Including a filter inside a cooler can lead to problems with clogging and requires the use of at least one O-ring seal to facilitate changing the filter element. Under high-pressure flow, O-ring seals tend to leak, potentially resulting in fluid loss and danger to users. Further, the Booth cooler is a single-pass cooler, resulting in fluid being retained in the cooler structure for a limited period of time, lowering cooling efficiency, and requiring hose connections at both ends of the long cooler structure.

FIG. 2 illustrates a transmission oil cooler, marketed by Specialty Auto Tech (SAT), Inc., of Rancho Cucamonga, Calif. In the SAT cooler, a single, axial, wall divides the cooler in half, routing the transmission oil in and out of the same end of the cooler.

Oil flows into housing 203, in direction 270, though fitting 264 and hole 265 of end cap 262, which is welded into housing 203. Housing 203 is divided into upper chamber 253 and lower chamber 255 by wall 250. Wall 250 is provided with upward dimples 251 and downward dimples 252, which direct oil toward inner fins 207, away from wall 250. Oil proceeds in direction 271, through aperture 254. Oil returns through lower chamber 255 and exits housing 203 in direction 272, through hole 266 and fitting 267 in end cap 262, which is welded to housing 203. The other end of vessel 203 is capped by end cap 260. Outer fins 205 (bare aluminum) conduct heat to the air.

The SAT cooler sends oil through two passes (channels 253 and 255). While the two passes do increase cooling efficiency, the cooler is still required to be long to increase surface area to further increase efficiency. Further, the large channel size in both the Booth and SAT coolers contribute to formation of air bubbles, which keep liquid away from the heat-exchanging surfaces (e.g., fins 7 and 207), further lowering cooling efficiency.

Typical automobile radiators use bent metal tubes to create desirable multiple fluid cooling passes. However, the tube structures in typical radiators are difficult to bend over tight radii, require several assembly steps to bend and mount to heat-exchanging structures, take up significant volume (because each part of the tube must withstand fluid pressure), and do not typically achieve high conduction efficiency to the structures to which they are attached.

Therefore, what is required is a compact cooler with small multiple channels, requiring minimal wall material, to provide safe and highly efficient cooling.

SUMMARY

Embodiments include coolers for cooling hot fluids, comprising a vessel provided with multiple inner channels for fluid flow and heat exchange. In some embodiments, the vessel is formed by extrusion.

Embodiments include low-pressure coolers, provided with six inner channels, formed by a baffle assembly, in which cooling fluid makes four passes through the six channels of the cooler. Embodiments include high-pressure coolers, provided with four inner channels, formed by a baffle assembly, in which cooling fluid makes four passes through the four channels of the cooler.

Embodiments include methods of cooler manufacture, comprising cutting a piece of extruded vessel material to a desired length, inserting a baffle assembly, and welding on end caps.

Embodiments include fluid coolers, surrounded by airflow assemblies, to facilitate exchange of heat with the ambient environment. In some embodiments, cooling is further facilitated with an air fan. In some embodiments, the fan is switched on and off by means of a temperature sensor integrated in contact with the cooler.

BRIEF DESCRIPTION OF THE ILLUSTRATIONS

FIG. 1 (prior art) is an illustration from U.S. Pat. No. 4,207,187 to Booth.

FIG. 2 (prior art) is an illustration of a double-pass transmission fluid cooler.

FIG. 3A is an assembly view of a six-channel fluid cooler, according to of the present invention.

FIG. 3B is an external view of a six-channel fluid cooler, according to the present invention.

FIG. 4A is an end-view of a six-channel baffle assembly, according to the present invention.

FIG. 4B is a lateral view of a six-channel baffle assembly, according to the present invention.

FIG. 4C is a diagram of six-channel fluid flow, according to the present invention.

FIG. 5A and FIG. 5B are end and side views of an end cap, according to the present invention.

FIG. 6A and FIG. 6B are end and side views of an end cap with inlet and outlet ports, according to the present invention.

FIGS. 7A and 7B are end views of a cooling vessel with and without baffles inserted, according to the present invention.

FIG. 8 is a schematic diagram of an application of a fluid cooler, according to the present invention.

FIG. 9A is a perspective view of a four-channel fluid cooler baffle assembly, according to of the present invention.

FIG. 9B is an end view of a four-channel fluid cooler vessel and baffle assembly, according to the present invention.

FIG. 10 is a perspective view of a cooler with an airflow assembly, according to the present invention.

DESCRIPTION

FIG. 3A and FIG. 3B are assembly and external views of a six-channel, four-pass, fluid cooler, according to the present invention. Multi-pass cooler 300 is formed of vessel 310, baffle assembly 320, first end cap 340, and second end cap 342. Vessel 310 includes internal cylindrical chamber 314, capable of withstanding the pressure of hot, compressed fluid being pumped through it. For example, a wall thickness of approximately 0.072 in. (0.065-0.080) of a two-inch aluminum vessel provides sufficient strength for vessel 310 to be used for a cooler, under a static pressure of 3000 psi. Vessel 310 may be formed by many processes, including casting, extrusion, machining, or any other method of creating a robust vessel. In some embodiments, vessel 310 is formed out of aluminum, for improved heat transfer, strength, low-weight, and relative ease of welding. However, other materials, such as steel, copper, ceramic, silicon carbide, alumet, high temperature plastics, or other materials with appropriate strength and relatively high thermal conductivity (e.g., similar to or greater than that of aluminum) may be used.

By flowing the fluid through multiple (more than two) channels, multi-pass coolers lower the occurrence of air bubbles and effectively increase the length (and therefore efficiency) of cooling, by maintaining fluid in the cooler for a longer time than a single or double pass cooler.

In some embodiments, vessel 310 includes outer fins 312, to facilitate conduction of heat from vessel 310 to the ambient environment, or another external heat-conducting medium (e.g., water, oil). In some embodiments outside surface 316 of vessel 310 is coated with high-temperature, high-emissivity paint (such as produced by Aremco) to facilitate radiation of heat to the ambient environment. In some embodiments, outer surface 316 is left as bare metal, brushed, or coated (e.g., anodized, glazed, painted). In some embodiments, mounts 318 are attached to (or formed as part of) vessel 310, in order to allow it to mount to another piece of machinery, for example, to the frame rail of a vehicle.

In some embodiments, baffle assembly 320 is formed of baffles 321, 322, 323, 324, 325, and 326, arranged around center axis 328, forming six channels. Sets of holes 330 and 332 allow fluid to flow between channels.

In some embodiments, baffle assembly 320 and vessel 310 are formed as separate pieces. Extrusion, particularly of long, complex assemblies, having small internal volumes can be challenging. Therefore, vessel 310 is extruded, but baffle assembly 320 is formed separately. In some embodiments, baffle assembly 320 is inserted into vessel 310 and tack-welded, so it will not rotate. Vessel 310 is sealed by end cap 340 (equipped with inlet port 344 and outlet port 346) and end cap 342, which are welded in-place. Inlet port 344 and outlet port 346 are capable of attaching to lines 350 and 354, to allow fluid to enter in direction 352 and exit in direction 356.

FIG. 4A is an end-view of a six-channel, four-pass, baffle assembly, according to the present invention. Baffle assembly 320 is shown in chamber 314 of vessel 310. Baffle assembly 320 divides chamber 314 into axial channels (a-f).

In some embodiments baffles 321-326 are arranged at equal angular spacing, 60 degrees apart. In some embodiments, channels a and d occupy 72 degrees, while channels b, c, e, and f occupy 54 degrees, allowing extra space for fluid input and output. However, intermediate or exaggerated angular spacing may be used, if sufficient room remains for input and output ports, and if there is consistent flow of fluid through the channels. In some embodiments (for example, for transmission fluid cooling), baffles 321-326 are formed of aluminum, with a thickness of 0.040 to 0.060 inches.

Heat conduction from baffle assembly 320 to vessel 310 is very high, and issues of differential expansion between baffle assembly 320 and vessel 310 are reduced. There is also no issue of rotational alignment between baffle assembly 320 and vessel 310. An additional benefit is that if long extrusions (vessel blanks) are produced, they can be cut into vessels (segments of the vessel blank) of any desired length, simplifying the manufacture of varying lengths of coolers. However, the state-of-the-art of metal extrusion may limit the sizes, lengths, and quality of these embodiments as extrusions with complex internal structures are difficult to cool uniformly.

FIG. 4B is a lateral view of six-channel baffles, according to the present invention. In some embodiments, baffles 321, 323, 324, and 326 have semi-circular holes, 330, at the first end of baffle assembly 310, near cap 342. Baffles 322 and 325 are shown with semi-circular holes 332 at the second end of baffle assembly 320, near cap 340. Holes 330 and 332 allow fluid-flow to transfer to the next channel and return the other direction. In the example of an approximately 2-inch transmission fluid cooler, holes 330 and 332 have approximately {fraction (5/32)}-inch radii, to provide even distribution of fluid into multiple channels.

In some embodiments, holes 330 and 332 are replaced or supplemented with other apertures (e.g., semi-circles, circles, squares, rectangles, ovals) in other locations, or baffles 321-326 are shortened at the appropriate end to provide a means for fluid to pass between channels. For example, baffles 321, 323, 324, and 326 can be cut (e.g., ground, sawed, snipped, welded) at line 431 and baffles 322 and 325 can be cut at line 433. In some embodiments, where vessel 310 and baffle assembly 320 are a single extrusion, holes 330 and 332 are ground or cut from the ends of baffles 321-326 after vessel 310 is cut to the desired length from the extruded vessel blank.

In some embodiments, baffle assembly 310 is formed by welding baffles 321-326 together at a common axis. In some embodiments, baffle assembly 310 is formed of three V-shaped sections welded together.

FIG. 4C is a diagram representing fluid flow through a six-channel, four-pass, baffle assembly, according to the present invention. Referring to FIG. 4B, fluid flows into channel a, between baffles 321 and 326, through holes 330 in baffles 321 and 326, then back through both channel b, between baffles 321 and 322, and channel f, between baffles 326 and 325. Fluid then flows through holes 332 in baffles 322 and 325 to channel e, between baffles 324 and 325, and channel c, between baffles 322 and 323. Fluid then flows along channels e and c, through holes 330 in baffles 323 and 324 to channel d, and returns along channel d, between baffles 323 and 324. By dividing axial volume 314 into small channels (a-f), air bubbles, which may form in large channels, are discouraged.

The length of time hot fluid is contained in the vessel, in part, determines the amount of cooling. Increasing time in the vessel increases heat transfer. Therefore the four passes through six-channel cooler 300 effectively lengthens cooler 300, providing efficient cooling than a single or double pass cooler. In the example of automotive transmission fluid cooling, an 18-inch-long cooler, having an approximately 2-3 inch diameter chamber significantly increases vehicle cooling. While some types of coolers use bent metal tubes to increase fluid travel length, it is difficult to bend tubes in a small space. Thus, cooler 300 provides efficient cooling by virtue of multiple passes and takes up a small space by virtue of baffle assembly 320 being used in preference to tubes.

Small channels force fluid against the walls of vessel 310, providing good heat-exchange, whereas larger channels may result in lower pressure fluid flowing away from the walls of vessel 310.

FIG. 5A is an end view of an end cap, according to the present invention. In some embodiments, end cap 342 is formed out of the same material as vessel 310 (e.g., aluminum), in order to minimize differential expansion as cooler 300 is heated by hot fluid. In some embodiments, end cap 342 has a diameter of 1¾-inches.

FIG. 5B is a side view of an end cap, according to the present invention. In some embodiments, end cap 342 is provided with bevel 543, for aesthetic and safety purposes. End cap 342 is formed with a stepped shape in order to facilitate welding and to provide increased pressure containment by allowing increased fill with weld.

FIG. 6A is an end view of an end cap with inlet and outlet ports, according to the present invention. End cap 340 is formed with inlet port 344 and outlet port 346. Inlet port 344 is positioned to line up with channel a, and outlet port 346 is positioned to line up with channel d. Inlet port 344 and outlet port 346 may be threaded with thread 348 or provided with any convenient fluid interface. Port and thread sizes can be chosen to accommodate standards in the industry or type of machine for which cooler 300 is intended. For example, for use in vehicle cooling, some embodiments have thread 648 cut as ¼-inch National Pipe Thread (NPT) standard threads.

In some embodiments, end cap 340 is ⅛-inch larger than end cap 342 (1 and ⅞-inches) to provide sufficient space for inlet port 344 and outlet port 346 without weakening its structure.

FIG. 6B is a side view of an embodiment of an end cap provided with a transition, according to the present invention. End cap 340 is formed with a stepped shape in order to facilitate welding and to provide increased pressure containment by allowing increased fill with weld. In some embodiments, end cap 340 is provided with bevel 543, for aesthetic and safety purposes.

FIG. 7A and 7B are end views of a cooling vessel with and without baffles inserted, according to the present invention. Internal cooling fins 411 and 413, of different lengths, are added to increase heat transfer from the fluid.

In some automotive applications, cooler 300 is sized per the following example. In an approximately 2-inch cooler, twenty outer fins 312, set at even spacing 740 (18 degrees), extend to diameter 702, 3-inches. Fins 312 join vessel 310 at bend radius 732 (0.060 inches), in preference to a right angle, to maximize conduction and to add strength to vessel 310. Outer fins 312 are formed with width 720, 0.060-inches, and terminate in an arc of radius 730, 0.020 inches.

Vessel 310 is approximately 18-inches long and has outer diameter 704 of 1.9 inches and inner diameter 706 of 1.75 inches. Inner fins 411 extend to limit diameter 708 of 1.26 inches, and inner fins 413 extend to limit diameter 710 of 1.06 inches. Fins 411 and 413 are approximately 0.040 inches thick, terminating in an arc of radius 730, 0.020 inches.

In some embodiments, vessel 310 is formed for later insertion of baffle assembly 320 by extrusion, machining, or casting, and internal fins 412 and/or 413 are used to hold baffle assembly 310 in correct rotational alignment, baffles 321-326 being tack-welded between pairs of fins 411, 413.

FIG. 8 is a schematic diagram of an application of a multi-pass fluid cooler, according to the present invention. As an example, vehicle 800, having transmission 820, is shown equipped with cooler 300. In some embodiments, mounts 318 of cooler 300 are suitable for mounting cooler 300 to frame rail 810. Pump 821, representative of any fluid pump in a system to be cooled, pumps fluid out of transmission 820, through line 352, which is attached to inlet port 344 of cooler 300. The fluid exchanges heat through cooler 300 to the ambient environment, and exits cooler 300 through outlet port 346. Fluid returns through line 356, attached to outlet port 346, to transmission 820. In vehicular applications, it can be advantageous to mount cooler 300 outside vehicle 800, where cooler 300 can receive the benefit of flowing air as the vehicle moves, to further facilitate cooling.

While FIG. 8 shows transmission 820 and vehicle 800 as an illustrative example application and location of cooler 300, those skilled in the art will appreciate that cooler 300 is applicable for use with many different types of machinery (e.g., vehicle engines, machinery engines, hydraulic equipment), and mounted in many different locations, where it could be attached to cooling lines, such as 352 and 356, and maintain contact with a heat exchanging medium (e.g., air, water, oil). Those skilled in the art will also appreciate that cooler 300 can cool many types of fluids (e.g., engine oil, hydraulic fluid, water). While the above-described approximately 2-inch diameter, approximately 18-inch long, six-channel, four-pass cooler is exemplary of coolers for transmission fluid cooling. The approximate 2-inch size conveniently fits under or in the engine compartment of a typical automobile. However, embodiments of different sizes and/or proportions have many different applications.

FIG. 9A is a perspective view of a four-channel, four-pass internal baffle assembly, according to of the present invention. In some embodiments, cooler 300 is provided with four-channel, four-pass baffle assembly 900 rather than six-channel baffle-assembly 320. In some embodiments, upper baffle 910 includes planes 912, 914, and 916, and forms the first of the four channels. In some embodiments, planes 912 and 916 are 72 degrees apart.

Upper baffle 910 is joined to lower baffle 930 (including planes 932, 934, and 936) by middle baffle 920. Plane 916 is provided with aperture 918. In some embodiments, aperture 918 is an elongated slit, as shown in FIG. 9A. Providing a high pressure, four-channel cooler baffle assembly with slits, rather than semicircles (see FIG. 3A), provides less resistance to fluid flow and facilitates cooler of higher flow rate liquids, such as automotive oil. Middle baffle 920 and plane 936 are similarly provided with apertures 928 and 938, respectively.

FIG. 9B is an end view of a four-channel fluid cooler vessel and internal baffle assembly, according to the present invention. Fluid enters baffle assembly 900 from port 344 and flows along the first channel, formed between planes 912, 914, and 916 (and a portion of the internal wall of vessel 310). Fluid then flows through aperture 918 in plane 916 into and along the second, intermediate, channel, formed between plane 916, middle divider 920, and plane 932 (and a portion of the internal wall of vessel 310). Fluid then flows through aperture 928 in middle divider 920 and into and along the third, intermediate, channel formed by plane 912, middle divider 920, and plane 936 (and a portion of the internal wall of vessel 110). Fluid then flows through aperture 938 in plane 936 and into and along the fourth, last, channel formed by planes 936, 934, and 938 (and a portion of the internal wall of vessel 310), exiting through port 346.

As fluid passes through the channels, it exchanges heat with baffle assembly 900, and vessel 310. Heat exchange with vessel 310 is facilitated by larger internal fins 411 and smaller internal fins 413. In some embodiments, baffle assembly 900 is made from material approximately 0.049 to 0.058 inches thick. Baffle assembly 900 is secured in vessel 310 against larger internal fins 411, and can be tack-welded to keep it from shifting position in cooler 300.

Embodiments including four-channel, four-pass coolers are efficient for cooling of high-flow-rate coolants, for example, automobile oil and water cooling systems. An advantage of four-channel embodiments is that fewer, larger channels facilitate higher-flow-rates, and it is possible to cut larger apertures (as shown in FIG. 9A) between the baffles of four-channel assemblies.

FIG. 10 is a perspective view of a cooler air flow assembly, according to the present invention. In some embodiments, cooler 300 is surrounded by air pipe 1010. Air pipe 1010 directs air to pass by outer fins 312 of cooler 300, drawing heat out of cooler 300 more efficiently than would static air. Air pipe 1010 has an inner diameter matching the outer diameter of fins 312, for example 3-inches and can form a friction fit to cooler 300. In some embodiments, air pipe 1010 has a wall thickness of 0.062 inches.

In some embodiments, air pipe 1010 includes fan 1020. Fan 1020 provides airflow through air pipe 1010 when there is no (or little) air flowing in direction 1011. As an example, fan 1020 may be a 2.8 amp fan, operating at approximately 9500 rpm. In embodiments where cooler 300 is mounted on a vehicle, fan 1020 is capable of providing air flow when the vehicle is stopped or moving too slowly to provide sufficient air for heat exchange with cooler 300. Heated air exits through air-port 1028.

In some embodiments, fan 1020 includes blade 1024 and is mounted in fan housing 1026, by fan mount 1022. Fan 1020 is provided with power over lines 1021, which may be provided by a vehicle power system.

In some embodiments a relay or switch (for example in vehicle 800) determines when power is provided to fan 1024. In some embodiments, cooler 300 is provided with thermostat 1030 and control electronics 1032 (e.g., relay, electronic switch), so that fan 1020 may be switched on and off according to the temperature of cooler 300 (and thus the fluid inside it).

While various embodiments of the invention have been described, it should be understood that they have been presented by way of example and not limitation. Those skilled in the art will understand that various changes in forms or details may be made without departing from the spirit of the invention. Thus, the above description does not limit the breadth and scope of the invention as set forth in the following claims.

Claims

1. A multi-pass cooler, comprising:

a heat-conducting vessel provided with an internal cylindrical chamber, having a first end and a second end, comprising:

an internal baffle structure, comprising: a plurality of baffles, forming a multiplicity of channels, the multiplicity comprising a first channel, intermediate channels, and a last channel; a first end cap, fixed to the first end of the heat-conducting vessel; and a second end cap, comprising an inlet port and an outlet port, fixed to the second end of the heat-conducting vessel; wherein, the inlet port is capable of receiving a fluid and directing the fluid into the first channel, and the outlet port is capable of receiving the fluid from the last channel, and directing the fluid out of the cooler.

2. The multi-pass cooler of claim 1, wherein the baffle structure comprises six baffles forming six channels.

3. The multi-pass cooler of claim 2 wherein the six baffles are spaced at 60 degree angles.

4. The multi-pass cooler of claim 2, wherein two channels are formed by baffles spaced at 72 degrees and four channels are formed by baffles spaced at 54 degrees.

5. The multi-pass cooler of claim 1, wherein the baffle structure comprises three baffles forming four channels.

6. The multi-pass cooler of claim 5, wherein two of the channels are formed by baffles spaced at a 72 degree angle and two of the channels are formed by baffles spaced at a 104 degree angle.

7. The multi-pass cooler of claim 6, wherein slits are provided at a portion of the ends of a portion of the baffles to facilitate fluid flow between channels.

8. The multi-pass cooler of claim 7 wherein the vessel further comprises external heat-transfer fins; and internal heat-transfer fins.

9. The multi-pass cooler of claim 8, wherein the conducting vessel is formed by extrusion of aluminum.

10. A multi-pass fluid cooler, comprising:

a vessel, comprising a cylindrical inner volume, a heat-radiating outer surface, a heat-conducting inner surface, a first end opening, and a second end opening;

a baffle structure, comprising: a first baffle, comprising an exit hole; a second baffle, comprising an entrance hole and an exit hole; a third baffle, comprising an entrance hole and an exit hole; a fourth baffle, comprising an entrance hole; a fifth baffle, comprising an entrance hole and an exit hole; and a sixth baffle, comprising an entrance hole and an exit hole;

wherein, the first baffle, second baffle, third baffle, fourth baffle, fifth baffle, and sixth baffle radiate from a central axis, and extend to substantially fill the cylindrical inner volume of the vessel;

a first end-cap, fastened to the first end opening of the vessel; and

a second end-cap, comprising an inlet port and an outlet port, fastened to the second end opening of the vessel, wherein the inlet port is located between the first baffle and the second baffle of the baffle structure, and the outlet port is located between the fourth baffle and the fifth baffle of the baffle structure.

11. The multi-pass cooler of claim 10, wherein the vessel is extruded of aluminum.

12. The multi-pass cooler of claim 11, wherein the vessel cylindrical inner volume has a diameter between 1 and 3 inches.

13. A method of making a cooler, comprising the steps of:

a. Extruding a vessel blank, comprising a plurality of external cooling fins, and a plurality of internal cooling fins;

b. Creating a vessel by cutting a segment of the vessel blank to a desired length, having a first end and a second end;

c. Inserting a baffle assembly, comprising: a plurality of baffles provided with apertures for fluid flow;

d. Forming a first end cap.

e. Welding the first end-cap onto the first end of the vessel;

f. Forming a second end cap, provided with an inlet port and an outlet port; and

g. Welding the second end-cap onto the second end of the vessel.

14. A four-pass fluid cooler, comprising:

a vessel, comprising a cylindrical inner volume, a heat-radiating outer surface, a heat-conducting inner surface, a first end opening, and a second end opening;

a baffle structure, positioned in the vessel, comprising: an upper baffle, comprising an exit slit, forming an upper channel; an intermediate baffle, comprising an entrance slit and an exit slit, forming two intermediate channels; a lower baffle, comprising an entrance slit, forming a lower channel;

a first end-cap, fastened to the first end opening of the vessel; and

a second end-cap, comprising an inlet port and an outlet port, fastened to the second end opening of the vessel, wherein the inlet port is aligned with the upper channel and the outlet port is aligned with the lower channel.

15. The four-pass fluid cooler of claim 14, wherein the upper baffle and lower baffle are each formed of a horizontal plane segment and two angled plane segments, and wherein the intermediate baffle is a vertical plane segment.

16. The four-pass fluid cooler of claim 15, wherein the two angled plane segments of the upper baffle and of the lower baffle angled at approximately 72 degrees to each other.

17. The four-pass fluid cooler of claim 16, wherein slits are provided at a portion of the ends of a portion of the baffles to facilitate fluid flow between channels.

18. The four-pass fluid cooler of claim 17, wherein the conducting vessel is formed by extrusion of aluminum.

19. The cooler of any of claims 2, 5, 14, or 18, further comprising an airflow assembly, comprising an air pipe surrounding a portion of the cooling vessel, and having a fan at one end.

20. The cooler of claim 19, further comprising a temperature sensor, in thermal contact with the vessel, capable of turning the fan off and on.