In a radiant heating box there is a convection current which flows over the surface of tubes in the box. Adding ribs to the external surface of vertical tubes provides an enhancement to the heat transfer by convection and increases the heat transfer to the tubes.
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What is claimed is: 1. A method to increase by at least 5% the convection heat transfer from an external fluid heat transfer medium to a vertical surface selected from the group consisting of metal or ceramic in a radiant fired heater box, and increasing the total heat flux into the surface by at l
What is claimed is: 1. A method to increase by at least 5% the convection heat transfer from an external fluid heat transfer medium to a vertical surface selected from the group consisting of metal or ceramic in a radiant fired heater box, and increasing the total heat flux into the surface by at least 2% used to heat an internal process fluid by increasing the turbulent flow of the fluid heat transfer medium at the external surface comprising forming on the external surface ribs which have: (i) a ratio of the rib height to the diameter of the tube (e/D) from 0.05 to 0.35; (ii) a ratio of the distance between the leading edge of consecutive ribs to rib height (P/e) less than 40; and (iii) a ratio of the thickness of the rib to the height of the rib (t/e) from 0.5 to 3. 2. The method according to claim 1, wherein the rib has an e/D ratio from 0.1 to 0.25. 3. The method according to claim 2, wherein the rib has a P/e ratio from 2 to 20. 4. The method according to claim 3, wherein the rib has a t/e ratio from 1 to 2. 5. The method according to claim 4, wherein the rib has a cross section profile selected from the group consisting of a square, a triangle, semi-circular and semi-elliptical. 6. The method according to claim 5, wherein the surface is selected from the group consisting of stainless steel, cast alloys, wrought alloys, carbon steel and ceramic. 7. The method according to claim 6, wherein the surface is one or more tubes. 8. The method according to claim 7, wherein said one or more tubes have an external diameter up to 8 inches. 9. The method according to claim 8, wherein the external fluid heat transfer medium is a gas selected from the group consisting of the combustion products of hydrogen, hydrocarbons and a mixture thereof. 10. The method according to claim 9, wherein the internal process fluid is selected from the group consisting of ethane, propane, butane, naphtha, gas oils, dilution steam, and mixtures thereof. 11. The method according to claim 10, having an internal surface resistant to coking. 12. The method according to claim 10, wherein the rib has a P/e ratio from 4 to 16. 13. The method according to claim 12, wherein the convection heat transfer is increased by at least 8%. 14. The method according to claim 13, wherein the rib has a triangular, semi-circular or semi-elliptical cross section profile. 15. The method according to claim 14, wherein the rib is horizontal. 16. The method according to claim 14, wherein the rib is helical. 17. The method according to claim 15, wherein said one or more tubes have an internal surface resistant to coking. 18. The method according to claim 17, wherein one or more tubes further have one or more internal modifications to increase heat transfer. 19. The method according to claim 16, wherein said one or more tubes have an internal surface resistant to coking. 20. The method according to claim 19, wherein said one or more tubes further have one or more internal modifications to increase heat transfer. 21. A tube used in a chemical reaction requiring the input of heat to the reaction having on the external surface of the tube ribs which have: (i) a ratio of the rib height to the diameter of the tube (e/D) from 0.05 to 0.35; (ii) a ratio of the distance between the leading edge of consecutive ribs to rib height (P/e) less than 40; and (iii) a ratio of the thickness of the rib to the height of the rib (t/e) from 0.5 to 3. 22. The tube according to claim 21, made from a material selected from the group consisting of stainless steel, cast alloys, wrought alloys, carbon steel and ceramic. 23. The tube according to claim 22, having an e/D ratio from 0.1 to 0.25. 24. The tube according to claim 23, having a P/e ratio from 2 to 20. 25. The tube according to claim 24, having a t/e ratio from 1 to 2. 26. The tube according to claim 25, wherein the rib has a cross section profile selected from the group consisting of a square, a triangle, semi-circular and semi-elliptical. 27. The tube according to claim 26, wherein the rib has a triangular, semi-circular or semi-elliptical cross section profile. 28. The tube according to claim 27, wherein the rib is horizontal. 29. The tube according to claim 27, wherein the rib is helical. 30. The tube according to claim 28, having an internal surface resistant to coking. 31. The tube according to claim 28, wherein the tube further has one or more internal modifications to increase heat transfer. 32. The tube according to claim 31, wherein the tube further has one or more internal modifications to increase heat transfer. 33. The tube according to claim 29, having an internal surface resistant to coking. 34. The tube according to claim 29, wherein the tube further has one or more internal modifications to increase heat transfer. 35. The tube according to claim 34, wherein the tube further has one or more internal modifications to increase heat transfer. 36. A process to make a rib on a metal tube according to claim 22, comprising one or more processes selected from the group consisting of casting, machining, and welding. 37. A process to make a rib on a metal tube according to claim 22, comprising depositing additional material. 38. A process to make a rib on a ceramic tube according to claim 22, comprising one or more processes selected from the group consisting of casting, and machining. 39. A process to make a rib on a ceramic tube according to claim 22, comprising depositing additional material.
Fishgal Semyon I. (1908-35 High Park Ave. Toronto CAX) Fishgal Aleksander S. (1908-35 High Park Ave. Toronto CAX) Pass-Fishgal Irina G. (1908-35 High Park Ave. Toronto CAX M6P 2R6), Hollow article with zigzag projections.
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