Search results

  1. M

    Heat transfer and combustion correlations

    Your thermal conductivity is given in kW m-1 k-1 this will give your answer x10-3 kW m-2 k-2 which when you covert to W you get your answer
  2. M

    Heat transfer and combustion correlations

    Yes that looks correct but there needs to be a power of 0.25 at the end of your equation
  3. M

    Heat transfer and combustion correlations

    Try working out the nusselt number with the values given and 0.915 you worked out. Once you have nu you can then put this into the heat transfer coefficient equation
  4. M

    Heat transfer and combustion correlations

    I am not sure what you are trying to do? Your 0.915 is essentially Pr but you can just plug the values into the equation you quoted in post #18
  5. M

    Heat transfer and combustion correlations

    Yes you are correct on both counts
  6. M

    Flame Temperature

    Hi I will dig out my notes and let you know. I am not 100% off the top of my head Regards
  7. M

    Heat Transfer Coefficient -Air Flow onto perpendicular plane

    The air isn't coming from the vents it is being extracted there. The air is coming from above the surface being blown downwards
  8. M

    Heat Transfer Coefficient -Air Flow onto perpendicular plane

    Thanks for this guidance - much appreciated I will look into this as it is a practical problem Thanks again
  9. M

    Heat Transfer Coefficient -Air Flow onto perpendicular plane

    Is that not for just jets onto a heated surface? Rather than air? Thanks again
  10. M

    Heat Transfer Coefficient -Air Flow onto perpendicular plane

    Thanks, rough sketch shows the air being forced into surface, this will create turbulent flow? But can't find anything on how to approach this and it is both linear and turbulent to some extent Thanks
  11. M

    Heat Transfer Coefficient -Air Flow onto perpendicular plane

    Hi Nidum, thanks for your reply - yes I can attach a sketch although I am not too sure how to do it on this forum - any ideas? (Apologies)
  12. M

    Heat Transfer Coefficient -Air Flow onto perpendicular plane

    Hi All, I have a situation were I need to evaluate the heat transfer coefficient of a horizontal surface. The surface has tubes within although I first used "flow across a bank of tubes", this has been untrue due to the air flow coming from above the surface flowing vertically (and...
  13. M

    Mechanical principles rotating systems

    No problem, do u think that is on the right lines or way off?
  14. M

    Mechanical principles rotating systems

    5000N x 2m - ((m1 x .1m x157^2)x1.5) - ((m2 x .1m x 157^2)x0.5m) =0 10,000 - (m1 x 3697.35) + (m2x1232.45)=0 10000/(3697.35+1232.45)=m1+m2 2.028= m1+m2 Pretty sure this is wrong to be honest but not sure where to go from here or what approach I should be making Thanks
  15. M

    Mechanical principles rotating systems

    Homework Statement A shaft 2 m long rotates at 1500 revs min–1 between bearings as shown in FIGURE 2. The bearings experience forces of 5 kN and 3 kN acting in the same plane as shown. A single mass is to be used to balance the shaft, so that the reactions are zero. The mass is to be placed at...
  16. M

    Heat exchangers

    Ah so it is simply 300- 11.4 to give the outlet temperature of the flue gas?
  17. M

    Heat exchangers

    I'm not sure hahah! So what is the 11.4 difference in temperature?
  18. M

    Heat exchangers

    2113 kg/hr? I used the liquid heat cp 90c + 5bar + enthalpy of vaporisation 5 bar 4.208+2.32+2107=2113
  19. M

    Heat exchangers

    What would the usual difference be between inlet and outlet temperatures with regards to flue gas as I have worked it out although it barely differs from the inlet temp (around4 degrees) surely I have gone wrong?
  20. M

    Heat exchangers

    Thanks mate I will give it ago using this!
  21. M

    Heat exchangers

    Thanks for the explanation would you be willing to give me a formula to use I might be able to tackle it and give it a go that way Thanks
  22. M

    Heat exchangers

    Yes it is the final part there is one after the flame temp question that I believe to have completed just the notes are not very clear, The flow rate of flue gas is 1400 kmol h^-1 And it does not state any water feed rate, what is the equation that you are intending on using please
  23. M

    Heat exchangers

    Thanks for your reply, so is there a different equation that is used? Because you do not need to use specific heat capacity when using the method I described I believe
  24. M

    Heat exchangers

    Homework Statement If the flue gases exiting the boiler are used to preheat the water fed to the boiler from a temperature of 28 C to 90 C and assuming: • a mean specific heat capacity for water over this temperature range to be 4.2 kJ kg–1 K–1 a mean molar heat capacity for the flue...
  25. M

    Flame Temperature

    Hi I was wondering if you would know what equation to use for this ... (i) If 5% of the heat available for steam production is lost to the atmosphere, determine the amount of steam raised per hour when the total flow of flue gases is 1400 kmol h–1. Can I just deduct 5% from the heat...
  26. M

    Flame Temperature

    Ah I get this now I will re do this and hopefully it will work out- thanks for your help Much appreciated
  27. M

    Flame Temperature

    No problem, the lecturer has stated we can use the same value for both butane and butene although these are slightly different. 1-2% would not change my final value so it would fit that of the table. Is it possible it is above 2200 deg C or is this too high ? The question stated max temp so...
  28. M

    Flame Temperature

    I'm not sure how to obtain this value With the flue gas being a gas I'm assuming this is going to be a really low value?
Top