1. T

    Compressed air system question

    When dealing with a compressed air system I would like to know how to make some calculations to predict pressure and flow rate throughout a system. e.g. If I have a compressor that can supply 50 cfm @ 100 psi at the source, and the air flows through a system of pipes, filters, turns, etc...
  2. E

    Calculate the time it takes for river gravel to take on the same temperature as the a

    Heres the scenario: Water level drops in a river. The previously saturated gravel slowly takes on the same temperature as the air. Assuming the gravel was originally the same temperature as the water, and the surface is flat, How long does it take? I believe these are the relevant formulas...
  3. M

    Physics Software Thermodynamic limit in Monte Carlo simulation

    Hi guys. I'm using the Monte Carlo method to simulate a spin lattice. If I have a square lattice, L x L, I can plot the phase transition temperature by the inverse of the lattice length (1/L) to find the phase transition temperature in the thermodynamic limit (extrapolating the curve for...
  4. P


    The heat capacity of the interior of a refrigerator is 4.2 / kJ K . The minimum work that must be done to lower the internal temperature from 18 degree C to 17 degree C, when the outside temperature is 27 degree C will be
  5. L

    Thermodynamic Potential

    Hello, I came across the Lagrange Transformation explaining the Thermodynamic Potential. Textbooks show, how the math is executed. Can someone explain the practical use of transforming the energies pdV and TdS into Vdp and TdS. Regards Lothar
  6. A

    thermodynamic question

    What pressure increase is needed to make a cubic block of magnesium metal retain its initial volume while it is being heated from 0 to 50C? The average linear expansion coefficient αL = 2.5x10-7 K-1 , the isothermal compressibility factor β = 2.95x10-10 (N/cm2 )-1 .
  7. G

    Exact thermodynamic equation of state

    Dear all, I am using molecular dynamics to calculate energy for ionic liquid. In the article that is proposed equation of state that I want to use, the author would call the energy in the following formula(u) conformational(potential energy): (du/dv)T + T(dp/dT)V = ptot But the other article...
  8. A

    Thermodynamic question about open systems

    A steam turbine takes in steam, with specific enthalpy 3095 kJ/kg, the steam leaves the turbine with specific enthalpy 2660 kJ/kg, work output is 0.5 MW, If heat losses from the turbine are 120 kW, determine a) the mass flowrate of the steam. b) the work output per kilogram , assume that...
  9. A

    How to read a Thermodynamic table?

    When solving a word problem in Thermodynamics and are given both pressure and tempreature of a fluid or water, how do we know if we should get information about internal energy and entropy from the Pressure Table or the Temperature Table?
  10. J

    Thermodynamic phase problem

    Hello everyone i could really use help with the following problem as it has been puzzling me for a while.I do not really know where to start from so i would be really grateful if anyone could provide me with some guidelines or any help An experiment requires supplying a reactor with ammonia...
  11. B

    How do I determine the amount of water in a sealed container to create a given pressu

    I have a sealed container with a volume of 1 liter. I want to go from an initial pressure of p1=1 atm and an initial temperature of T1=298 to a final pressure of p2=10 atm and a final temperature of T2=453 K. I want to to use water to create the pressure. But I do not know how to determine the...
  12. S

    Thermodynamic problem

    A long, insulated tube (Fig. P4.21) is divided into chambers of equal volume by rigid, adiabatic partitions. Each partition has a fast operating valve to allow flow of gas between compartments when the valve is open. The operation of this device is as follows. Compartment A is initially filled...
  13. kelsiu

    Question about thermodynamic temperature derivation

    In deriving thermodynamic temperature scale, it uses the concept that heat transfer between two reservoirs is the function of the reservoirs' temperatures. i.e. Q1/Q2=Φ(T1,T2). And then further express that Φ(T1,T2)=ψ(T1)/ψ(T2). I have two questions. Is it a hidden assumption that the...
  14. B


    can anyone help me for this question? A gas at specified stagnation temperature and pressure is accelerated to M=2 in a converging-diverging nozzle and to M=3 in another nozzle , what can you say about the pressures at the throats of these two nozzles?
  15. kelsiu

    Questions about thermodynamic relations

    We know that for constant pressure thermodynamic processes which only expansion work is possible, dH=dQp. My question is, is it necessary that both work W and Qv be reversible to arrive this relation? What if the heat transfer is irreversible? Similar question for dU=dQv, does the heat...
  16. F

    thermodynamic bumble bees

    Physics in general is a grey area for me, as the same people who clearly state that perpetual motion is an impossibility, come from the same group of people that would have you believe that a bumble bee can not fly, due to its wings being far too small for its body. . Did the humble bumble bee...
  17. K

    Thermodynamic Efficiency

    Can any one pls tell me how solar power are transformed into electricity using a solar panel? Here in this page ( it is said solar cells maximum efficiency is only 44% why?
  18. H

    thermodynamic's first law

    Hi there, I have some simple questions in thermodynamics ... Hope I can find the correct answers to them *the quantities: pressure(P) , volume(V) , concentration , are called state function ... is this sentence correct or incorrect ? and why ? I obtained these from a youtube video: in...
  19. V

    Thermodynamic problem

    A working fluid in an engine executes a cyclic process and two work interaction are done. 40KJ to the working fluid and 30KJ from the working fluid The cycle also involves three heat interactions. 75KJ to the working fluid and 40KJ from the working fluid Determine the third heat interaction...