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  1. roaling

    Price estimation for air-cooled chillers

    Is there someone confirming that 100 $/kW is a good figure to roughly evaluate the price of air-cooled chillers for air-conditiong application in the range 600-1200 kW of refrigeration (170-340 RT)? Thanks in advance. Roaling
  2. roaling

    CO2 effect on flue gas dew point

    Thanks Guidoo. I know the relation between dew point and partial water vapor pressure. What is unknow to me is the relation with the H20-CO2 system that beeing an acid is a condensing agent. Good day, Roaling
  3. roaling

    CO2 effect on flue gas dew point

    The question is simple and clear. How does CO2 content effect the dew point of flue gas exhausted from natural gas fuelled gas turbine towards a HRSG? Thank a lot for your help.
  4. roaling

    Serrated fins

    To IRstuff. Frankly,I know something about plain fins but nothing on serrated. Reference books just to start with the principles and then more detailed info will be very much useful.
  5. roaling

    Serrated fins

    I should appreciate to have information, formulas and procedures on how calculate the heat transfer coefficient of tubes with serrated fins. Thanks for your help.
  6. roaling

    citric acid = lactic acid ?

    Try to drink a lemon juice and compare with a glass of milk. What do you prefer ? Sorry, your question is not well addressed.
  7. roaling

    NPSHA vs NPSHR

    You have two ways: to make calculation referring to feet or to psi. If you chose psi then you have to convert to feet. Anyway, your assumption to divide atmospheric pressure in feet by S.G. is correct.
  8. roaling

    NPSHA vs NPSHR

    Dear Morten, May be I was not clear. The correction factor to apply is on the NPSHR not NPSHA. In case of gasoline, I think that no correction is needed.
  9. roaling

    NPSHA vs NPSHR

    In calculating NPSHA you should refer to gasoline applying correction factor, if any, on NPSHR with water.
  10. roaling

    determining centrifugal pump flow rate

    Information from other guys are correct. I suggest you to refer to pipe size or discharge nozzle size assuming respectively a velocity of 2-2.5 m/s or 5-6 m/s. In this way it is very easy to roughly estimate the flow. For. ex. : 2.5*(3.1416*0.05^2/4)*3600 = 17.7 m3/h (checking the result with...
  11. roaling

    Droplet Size?

    Yes, MGlycol is right. A demister is more than what required. An adequately sized cyclone separator could be enough. Anyway, go ahead with the demister.
  12. roaling

    Inspection to double jacketed tank

    PlantEng, in your experience have you never seen vessel jacket of such dimensions to be inspected inside ? Do exist regulations requiring to inspect inside the jacket ? Thanks.
  13. roaling

    u/g tank heat loss calculation

    Sorry j I insist. Assuming 10 mm SS wall: 0.01/15 = 0.00067 8 mm air gap: 0.008/0.025 = 0.32 Assuming 10 mm CS wall: 0.01/40 = 0.00025 1/K = 0.00067 + 0.32 + 0.0025 = 0.32092 K = 3.12 W/sqm°C This figure differs from that calculated by you (17). Am I wrong ?
  14. roaling

    u/g tank heat loss calculation

    j, I think you are wrong. If gap thickness is only 8 mm, I should consider only air conductivity, so the coefficient is much lower. Unfortunately, I have Perry 6th and cannot check your reference.
  15. roaling

    Vacuum pump installed in a high position can give better vacuum

    In my opinion, the pump installation at high position is better to avoid any possible liquid carry-over and not to get an higher vacuum.
  16. roaling

    A sticky question of heat transfer

    I wish to thank all friends partecipating to this thread. On the basis of info had from you and others from my knowledge and library, I have reached the following conclusion. Disregarding the terms relevant to steel walls and glycol side, only three are partecipating to the heat transfer: -...
  17. roaling

    u/g tank heat loss calculation

    jmelia, thank for your clarification. Since I have a problem similar to yours, would you please specify how did you treat the air resistance and what is the gap thickness ? Apart from the soil, I think that the air chamber has a significant heat resistance. Thanks, Roal
  18. roaling

    u/g tank heat loss calculation

    Is the tank jacketed ? I expect yes because underground.
  19. roaling

    A sticky question of heat transfer

    Dear IRstuff, Tank dimensions are approx 9.5 x 4 x 4 m (LxWxH). Top of the tank is identical to the bottom; all wall surfaces are subject to a small internal pressure, approx 0.2 barg plus liquid head where applicable. The tank jacket is under higher pressure, approx 0.8 barg. The tank is...
  20. roaling

    A sticky question of heat transfer

    Awaiting other suggestions, I got the following result: 12 W/sqm. What do you think ? Thank again. A clarification: the steel wall in contact with the glycol is the enclosure of a rectangular tank of approx 120 cum capacity. The second steel wall is the outside enclosure of the tank jacket in...
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