An arrangement of fins or other convective heat transfer surfaces which provides an improved value of heat transfer per unit pressure drop of the flowing fluid, for a defined geometric envelope. There are at least two flowpaths in parallel. Each flowpath contains a wide densely-surfaced region, call
An arrangement of fins or other convective heat transfer surfaces which provides an improved value of heat transfer per unit pressure drop of the flowing fluid, for a defined geometric envelope. There are at least two flowpaths in parallel. Each flowpath contains a wide densely-surfaced region, called a heat transfer region, which accomplishes heat transfer at a reduced velocity whereby the ratio of heat transfer to pressure drop for that region is improved. In series with that region, in the same flowpath, is a narrow sparsely-surfaced region, called a fluid flow region, which serves to transport the fluid, at higher velocity but with minimal pressure drop, through the region(s) not densely-surfaced. The respective wide and narrow regions can be oppositely placed so that the overall arrangement maintains a constant width dimension so as to resemble conventional design. The invention is applicable to both forced and natural convection, and to laminar transition or turbulent flow, and is particularly applicable to gas side heat exchange.
대표청구항▼
An arrangement of fins or other convective heat transfer surfaces which provides an improved value of heat transfer per unit pressure drop of the flowing fluid, for a defined geometric envelope. There are at least two flowpaths in parallel. Each flowpath contains a wide densely-surfaced region, call
An arrangement of fins or other convective heat transfer surfaces which provides an improved value of heat transfer per unit pressure drop of the flowing fluid, for a defined geometric envelope. There are at least two flowpaths in parallel. Each flowpath contains a wide densely-surfaced region, called a heat transfer region, which accomplishes heat transfer at a reduced velocity whereby the ratio of heat transfer to pressure drop for that region is improved. In series with that region, in the same flowpath, is a narrow sparsely-surfaced region, called a fluid flow region, which serves to transport the fluid, at higher velocity but with minimal pressure drop, through the region(s) not densely-surfaced. The respective wide and narrow regions can be oppositely placed so that the overall arrangement maintains a constant width dimension so as to resemble conventional design. The invention is applicable to both forced and natural convection, and to laminar transition or turbulent flow, and is particularly applicable to gas side heat exchange. und around the rope drum, a pair of sliders connected to the pair of cables and moved by rotation of the rope drum, a pair of actuating bars pivotably coupled to the pair of sliders and tilted by relative movement of the sliders, a shade bar pivotably coupled to the other ends of the pair of actuating bars, a screen coupled to the shade bar, and a take-up shaft coupled to the other end of the screen and intended to elastically wind the screen. A drive assembly including the motor and the rope drum is mounted in a trunk to be isolated from an interior of an automobile, preventing transmission of noise from the assembly to the interior. The cables are maintained in tightened condition by a simple element, improving operational reliability of the apparatus. transfer surface area in contact with the fluid in the second channel upstream region, and the second channel downstream region, has a second channel downstream region total heat transfer surface area in contact with the fluid in the second channel downstream region, and wherein the first channel upstream region total heat transfer surface area and the second channel upstream region total heat transfer surface area define a heat transfer surface area distribution factor which is the larger of those two quantities divided by their sum, and the first channel upstream region flow cross-sectional area and the second channel upstream region flow cross-sectional area define a flow cross-sectional area distribution factor which is the larger of those two quantities divided by their sum, and wherein the heat transfer surface area distribution factor is greater than the flow cross-sectional area distribution factor. 2. The apparatus of claim 1, wherein the first channel flow of the fluid has a first channel flowrate and the second channel flow of the fluid has a second channel flowrate, and the first channel flowrate and the second channel flowrate are substantially equal to each other. 3. The apparatus of claim 1, wherein the first channel flow of the fluid has a first channel flowrate and the second channel flow of the fluid has a second channel flowrate, and the first channel flowrate and the second channel flowrate are substantially equal to each other. 4. The apparatus of claim 1, wherein the additional first channel upstream region heat transfer surface is substantially similar to the additional second channel downstream region heat transfer surface. 5. The apparatus of claim 1, wherein either the first channel upstream region or the second channel downstream region, or both, comprises: a first sub-channel comprising a first sub-channel upstream region having a first sub-channel upstream region flow cross-sectional area, in series with a first sub-channel downstream region having a first sub-channel downstream region flow cross-sectional area, the first sub-channel having boundaries disposed to engage in heat transfer with the fluid in the first sub-channel, and, in parallel with the first sub-channel, a second sub-channel comprising a second sub-channel upstream region having a second sub-channel upstream region flow cross-sectional area, in series with a second sub-channel downstream region having a second sub-channel downstream region flow cross-sectional area, the second sub-channel having boundaries disposed to engage in heat transfer with the fluid in the second sub-channel, and, in the first sub-channel upstream region, additional first sub-channel upstream region heat transfer surface disposed to engage in heat transfer with a first sub-channel fluid, and, in the second sub-channel downstream region, additional second sub-channel downstream region heat transfer surface disposed to engage in heat transfer with a second sub-channel fluid. 6. The apparatus of claim 1, further comprising a gradual transition between the first channel upstream region and the first channel downstream region, and a gradual transition between the second channel upstream region and the second channel downstream region. 7. The apparatus of claim 1, wherein the additional first channel upstream region heat transfer surface is configured as fins which are substantially parallel to the first channel boundary, and the additional second channel downstream region heat transfer surface is configured as fins which are substantially parallel to the second channel boundary. 8. The apparatus of claim 1, wherein the heat transfer surface area comprises fins which are flat in a first fin direction and curved in a second fin direction perpendicular to the first fin direction, and the flow of the first channel fluid and the flow of the second channel fluid have a common overall flow direction, and the overall flow direction is substantially along the first fin direction. 9. The apparatus of claim 1, wherein the heat transfer surface area comprises fins which are flat in a first fin direction and curved in a second fin direction perpendicular to the first fin direction, and the flow of the first channel fluid and the flow of the second channel fluid have a common overall flow direction, and the overall flow direction is substantially along the second fin direction. 10. The apparatus of claim 1, wherein the additional first channel upstream region heat transfer surface, or the additional second channel downstream region heat transfer surface, or both, comprises perforated fins, or one or more fins punctured by one or more fluid-carrying tubes, or wire mesh, or a porous material, or pins, or tubes in crossflow, or tubes in other geometries. 11. The apparatus of claim 1, wherein the apparatus is repeated a plurality of times side-by-side. 12. The apparatus of claim 1, wherein the flow in the first channel upstream region is in a regime which is selected from the group consisting of laminar flow, turbulent flow and transition regime flow, and the flow in the first channel downstream region is in a regime which is selected from the group consisting of laminar flow, turbulent flow and transition regime flow. 13. The apparatus of claim 1, wherein the fluid is selected from the group consisting of: a gas; a liquid; a mixture of an evaporating liquid and a gas; a mixture of a condensing gas and a liquid; a multi-phase fluid; and a supercritical fluid. 14. The apparatus of claim 1, wherein the flow is forced convection driven by a pump, fan, blower, impeller or compressor, or natural convection, or mixed convection. 15. The apparatus of claim 1, wherein the apparatus is part of a liquid-to-gas heat exchanger, an evaporator, a condenser, air conditioning or heating equipment, a vehicular radiator, a gas-to-gas heat exchanger, a heat sink for electronics or other purposes, process equipment, a process or power plant in which the circulating fluid is a gas, a process or power plant which rejects heat to the atmosphere, or a liquid-to-liquid heat exchanger. 16. The apparatus of claim 1, wherein the apparatus has a cylindrical geometry having an axial direction and a radial direction, and the first channel flow of the fluid and the second channel flow of the fluid have a common overall flow direction, and the overall flow direction is in the radial direction of the cylindrical geometry. 17. The apparatus of claim 1, wherein every point on every fin or heat transfer surface has a local surface temperature, and adjacent to every such point the fluid has a local fluid temperature, and the local surface temperature is everywhere greater than or equal to the local fluid temperature. 18. A method of promoting heat transfer with a flowing fluid, comprising passing the fluid through the apparatus of claim 1. 19. The apparatus of claim 1, wherein the heat transfer surface area distribution factor is greater than approximately 85% and the flow cross-sectional area distribution factor is between approximately 65% and 85%. 20. The apparatus of claim 1 wherein: the first channel upstream region total heat transfer surface area is the sum of the surface area of the first channel boundary in contact with the fluid in the first channel upstream region, plus the surface area of the interchannel boundary in contact with the fluid in the first channel upstream region, plus the surface area of the additional first channel upstream region heat transfer surface; and the first channel downstream region total heat transfer surface area is the sum of the surface area of the first channel boundary in contact with the fluid in the first channel downstream region, plus the surface area of the interchannel boundary in contact with the fluid in the first channel downstream region; and the second channel upstream region total heat transfer surface area is the sum of the surface area of the interchannel bounda ry in contact with the fluid in the second channel upstream region, plus the surface area of the second channel boundary in contact with the fluid in the second channel upstream region; and the second channel downstream region total heat transfer surface area is the sum of the surface area of the interchannel boundary in contact with the fluid in the second channel downstream region, plus the surface area of the second channel boundary in contact with the fluid in the second channel downstream region, plus the surface area of the additional second channel downstream region heat transfer surface. 21. The apparatus of claim 1, wherein the first channel upstream region flow cross-sectional area substantially equals the second channel downstream region flow cross-sectional area and the first channel downstream region flow cross-sectional area substantially equals the second channel upstream region flow cross-sectional area. 22. The apparatus of claim 1, wherein one or more of the left channel boundary, the right channel boundary and the interchannel boundary comprises a fin punctured by one or more fluid-carrying tubes. 23. The apparatus of claim 1, further comprising, in the first channel, a first channel extreme downstream region downstream of the first channel downstream region and substantially resembling the first channel downstream region, and in the second channel, a second channel extreme downstream region downstream of the second channel downstream region and substantially resembling the second channel upstream region, and further comprising a third channel boundary which is a heat transfer surface, the third channel boundary and the second channel boundary at least partially defining a third channel which is configured to confine a third channel flow of the fluid, the second channel boundary and the third boundary both being disposed to engage in heat transfer with the fluid in the third channel, the third channel being in parallel with the first channel and the second channel, the third channel comprising a third channel upstream region having a third channel upstream region flow cross-sectional area, in series with a third channel downstream region substantially resembling the third channel upstream region and having a third channel downstream region flow cross-sectional area, in series with a third channel extreme downstream region having third channel extreme downstream region flow cross-sectional area, the third channel extreme downstream region flow cross-sectional area being greater than the third channel downstream region flow cross-sectional area, and further comprising, in the third channel extreme downstream region, additional third channel extreme downstream region heat transfer surface disposed to engage in heat transfer with the fluid in the third channel extreme downstream region. 24. The apparatus of claim 1, wherein every point on every fin or heat transfer surface has a local surface temperature, and adjacent to every such point the fluid has a local fluid temperature, and the local surface temperature is everywhere less than or equal to the local fluid temperature. 25. An apparatus for engaging in heat transfer with a flowing fluid, comprising: a first channel boundary which is a heat transfer surface and an interchannel boundary which is a heat transfer surface, the first channel boundary and the interchannel boundary at least partially defining a first channel which is configured to confine a first channel flow of the fluid, the first channel boundary and the interchannel boundary both being disposed to engage in heat transfer with the fluid in the first channel; and a second channel boundary which is a heat transfer surface, located such that the interchannel boundary is between the first channel boundary and the second channel boundary, the second channel boundary and the interchannel boundary at least partially defining a second channel which is configured to confine a second channe
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