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Recent content by jehar

  1. jehar

    help with printing in VB .net

    Hi Leetech, If you are wanting to print the form, this is the method I use. For the form, Met3Grid, the code for the Print Form Button (Command4) is as shown below. Most of this code simply turns off stuff not to be printed and then after printing, turning the stuff back on. Private Sub...
  2. jehar

    ASME Heater versus API Heater

    You may want to visit http://www.HeaterDesign.com. Thanks, Jack Hardie
  3. jehar

    Fired Heaters convection and radiant sections

    Hi AndreChE, I am not sure why you are wanting to separate the radiant and convection for efficiency calculation. Doing it the way you are proposing gives you values for efficiency, but they don't have much meaning. Normally, the heater efficiency would be based on the...
  4. jehar

    Serrated fins

    Hi Roaling, Probably the best study of heat transfer coefficients for serrated fins was done by Escoa Fintube Company. They developed a complete method for thermal rating both solid and serrated fins. You can find their method explained as well as JavaScripts to do the calculations at...
  5. jehar

    Furnaces courses

    Yes, I do know a good furnace and combustion course, and it is online and free. Visit http://www.HeaterDesign.com Thanks, Jack Hardie
  6. jehar

    Sulfur dew point

    Sorry about the post with bad link, it should be http://www.jehar.com/online.stm
  7. jehar

    Sulfur dew point

    There are two sulphur dew point calculators at http://www.jehar.com/online.htm. These are in Javascript, so just right click on calculator and select view source to get formulas used.
  8. jehar

    Steam and Boilers

    You may find the answer you are looking for at http://www.HRSGdesign.com, under thermosyphon circulation. There are example calculations that show the relationship between the downcomers and risers and develops the mechanism that causes the cicuits to circulate. Jack
  9. jehar

    Boilers Softwares

    You may download WinBoil program for rating water-tube Heat Recovery Steam Generator type boilers at http://www.HeaterDesign.com/download/Winboil.exe Jack Hardie
  10. jehar

    Positive Heater Draft

    sshep, raises a very good point. Dampers are in stacks to control draft, not O2(air flow). The damper, which as mentioned, is useually not a full shut off type so as to prevent total closure, is there to prevent excess draft and is to be manipulated to reduce but not eliminate a negative draft...
  11. jehar

    Heat transfer coefficient

    You can find calculation methods for heat loss through insulation at http://www.HRSGdesign.com under "Other". And, you can find the publication "Determination of Heat Gain or Loss and the Surface Temperatures of Insulated Pipe and Equipment Systems by the Use of a Computer...
  12. jehar

    Positive Heater Draft

    Direct fired heaters can and are designed and manufactured for either positive of negative draft. The more common is the negative draft. The reason is that it is much more difficult to seal the casing and pipe portals for positive pressure. Hot flue gas leaks could cause structural failures...
  13. jehar

    Static Pressure calculation

    Hi, For help with pressure loss in ducting, enclosures, and other pieces, along with help in calculating the system pressures, go to http://www.HRSGdesign.com, under Process/Ducting Pressure Losses. Jack Hardie
  14. jehar

    thermic fluid heater design?

    I too have been attempting to find data on design of these heaters. I have a website at http://www.HeaterDesign.com/wintherm/ where I have been working on the design criteria and formulas, etc., for thermal fluid heaters. If anyone can contribute to this free educational web site development...
  15. jehar

    Coking versus fouling factor

    Anyone know of a fgood source for formulas to convert coke thickness from inches to hr-ft2-°F/Btu fouling factor as used in Thermal Design? How about roughness factor/friction factor when calculating pressure loss in tubes when fouled with coke? Thanks for any help.

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