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Viewing 15 posts - 16 through 30 (of 32 total)
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  • October 26, 2022 at 5:20 pm in reply to: Warming / Error #2381
    sreekanth.manavalla
    Participant

    For the compressor handling Helium between pressures of 0.65 and 15 bar and the inlet temperature of 252.23 C (to give h=1180 at inlet), the outlet temperature should be 1571 C to give an isentropic efficiency of 100%. If the exit temperature is more than that, the isentropic efficiency will be less than 100%.
    At isentropic efficiency of 100%, the exit enthalpy would be 8027 kJ/kg.
    So, in your case, since the exit enthalpy is less than 8027, the isentropic efficiency is greater than 100% implying that entropy is destroyed which is against 2nd law.

    October 15, 2022 at 5:06 am in reply to: Warming / Error #2321
    sreekanth.manavalla
    Participant

    Isentropic efficiency is computed using the specified inlet and outlet conditions. Dont have to specify. Check whether the entropy at outlet is lower than that at inlet?
    what is the fluid in this case?
    I did not find any image attached.

    October 13, 2022 at 6:22 pm in reply to: Warming / Error #2315
    sreekanth.manavalla
    Participant

    Is this apparatus 1 a compressor or pump? Probably the isentropic efficiency is more than 100%. In such case, this warning would be obtained. Please take a look at the inlet and outlet parameters.

    October 8, 2022 at 4:44 pm in reply to: NEGATIVE MASS FLOW IN PIPE #2295
    sreekanth.manavalla
    Participant

    When mass flow takes opposite to the intended direction, a warning of ‘Negative Mass Flow’ will be thrown at us by the software. In the legend, it appears as a negative number (e.g. -10 kg/s). Negative mass flow rate can be obtained in a heat exchanger when the cold fluid is placed on the secondary side etc.
    There can be other reasons for other components to result in having a nagative mass flow rate.
    It is a serious warning and cannot be ignored.

    September 28, 2022 at 6:45 pm in reply to: Error : Properties of REFPROP fluid not available #2220
    sreekanth.manavalla
    Participant

    Fluidprop does not contain Refprop by default. Refprop has to be purchased separately.
    In your case, you can try choosing your refrigerant from TPSI or freeStanmix fluid libraries.
    What is your refrigerant?

    September 25, 2022 at 4:57 pm in reply to: Excel file export / Sensitivity analysis #2204
    sreekanth.manavalla
    Participant

    It is not possible to transfer data to Excel automatically. Also, it is not possible to carry out a sensitivity analysis automatically. These must be done manually only.
    I am not sure if it can be done using user defined function.

    September 19, 2022 at 11:26 am in reply to: Helium Liquefaction System #2172
    sreekanth.manavalla
    Participant

    In my opinion, a General Separator must be used. You can specify which species to separate and in what amount.

    September 19, 2022 at 11:24 am in reply to: UNITS #2171
    sreekanth.manavalla
    Participant

    No. The units are fixed in SI system.

    September 19, 2022 at 11:24 am in reply to: ERROR_CYCLE TEMPO #2170
    sreekanth.manavalla
    Participant

    It is difficult to tell. I can try if you can mail me your file. My email ID is manavalla.sreekanth@vit.ac.in

    September 19, 2022 at 11:21 am in reply to: Moisture Separator #2169
    sreekanth.manavalla
    Participant

    As per my understanding, there must be 5 pipes.
    1. Gas inflow pipe
    2. Gas outflow pipe
    3. Separated moisture pipe
    4. Cooling medium inlet pipe
    5. Cooling medium outlet pipe

    August 10, 2022 at 4:47 pm in reply to: Heat Exchanger #1955
    sreekanth.manavalla
    Participant

    It is the Log Mean Temperature Difference (LMTD) which is negative. It could have happened if you have placed a cold fluid on the secondary side and hot fluid on the primary side.

    July 18, 2022 at 11:04 am in reply to: Ways of specifying mass flow rate #1829
    sreekanth.manavalla
    Participant

    Thanks for the clarification Dr. Teus.

    July 5, 2022 at 11:01 am in reply to: Negative Exergy destruction values #1773
    sreekanth.manavalla
    Participant

    In the attachment, sink/sources 2, 3 and 7 have negative exergy losses. Does it imply exergy generation?

    July 5, 2022 at 5:53 am in reply to: Calculation of specific heat capacities #1770
    sreekanth.manavalla
    Participant

    However, I think there is no harm in carrying out this little exercise of giving a small rise in temperature to compute the Cp using dH/dT

    July 5, 2022 at 5:12 am in reply to: TREACT in combustor #1769
    sreekanth.manavalla
    Participant

    Thank you for the detailed reply.

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Viewing 15 posts - 16 through 30 (of 32 total)
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