Recent content by Mr bboy

  1. M

    Pressure drop across a valve in hydraulics

    Thank you JBA for the answer. I have an additional question about your last comment: "a coefficient curve based upon flow vs lift or opening position is required." If i understand well the C coefficient will change with the ratio of the valve. Do you have an idea why in the theory for the...
  2. M

    Pressure drop across a valve in hydraulics

    Hello, I read something about the pressure drop across a valve and it was specified this is a singular pressure drop equivalent to K*U²/g (Borda formula). My question is, can we used the Bernouilli formula for a permanant incompressible flow to determine the flow rate function of the pressure...
  3. M

    Useful book to learn hydraulics and pneumatics

    Hello, I'm looking for some books which can help me to learn about hydraulic, pneumatic and fluid mechanics. Can someone advise me a good one ? Thank you !
  4. M

    Fuel cell open circuit voltage and pressure of reactants

    Hello, I have some questions regarding the nernst equation at open circuit voltage. We know E(OCV) = E0+ ln (PH2*PO2^0.5 / PH2O) I have some trouble with this: If I have dry gas (both for O2 and H2), and my circuit is open at 25°C and 1 atm I have no water in the circuit so what become the...
  5. M

    What is the Entropy of a Half Reaction?

    I understand know ! Thank you !
  6. M

    What is the Entropy of a Half Reaction?

    There is something i don't really understand. I looked for the hydrogen's entropy at standard conditions, i found 130.7 J K-1mol-1 In this following link ...
  7. M

    What is the Entropy of a Half Reaction?

    So for the half reaction at anode side I have to take account only the entropy of H2 ? At 293.13 K, for the Anode : 2*ΔS H+ + 2*ΔS e- - ΔS H2 we have ΔS=130.68 J/K/mol ? I just read in a thesis the author make the assumption ΔS at anode side is null and ΔG too (for the same reason you have...
  8. M

    What is the Entropy of a Half Reaction?

    Hi everybody, I have some troubles to define the enthalpy and entropy of a half reaction. If we consider the 2 following reactions : Anode : H2 = 2H+ + 2e- Cathode : 2H+ + 2e- + 1/2O2 = H2O So the global reaction is : H2 + 1/2O2 = H2O We know the global reaction's entropy can...
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