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May 25, 2019 · Flow work is input to system and is part of the energy that produces shaft work (output). It is not the shaft work itself. It is included as part of the enthalpy entering and exiting a control volume. An example is the input for a turbine that produces shaft work. The following is by way of explanation. There are basically two forms of ...
Jan 26, 2021 · Neither do I pretend the shaft work is the total work. The shaft work sign convention is valid regardless of the system being open/closed. But agree with bobd the sign is not important. $\endgroup$ –
dH = TdS + VdP = VdP δW = dH = VdP (isentropic dS = 0) Therefore VdP is isentropic shaft work from a flowing device. Important points: 1) Both internal energy and enthalpy are state variables, therefore can be measured for a system static or flowing. This is why sometimes there is a tendency to use U and H incorrectly.
Oct 23, 2022 · If the surroundings apply a force of 1334 N on the system, the system exert an equal and opposite force of 1334 N on the surroundings. And this force exerted on the surroundings is in the same direction as the piston displacement. So it is positive (shaft) work done on the surroundings. – Chet Miller.
It's just a convention in physics we are more interested in getting some work output say a mechanical device , engine etc while in chemistry we are more concerned with the internal energy things so we do so in both the cases the result is same physics case : du = dq - dw , doing work on system increases internal energy as dw = negative for work done on system and vice versa
Nov 2, 2020 · Nor is there any shaft work. So the area under the process 2-3 does not represent either boundary work or shaft work. The same applies to the condensation process 4-1. The only type of work done in the Rankine cycle is shaft work, the work of the pump and the turbine. The turbine work is the work done by the system (working fluid).
Sep 16, 2020 · 1. Let's say a steam turbine produces Wt. If the energy of the steam flow entering the turbine is equal to E3, and the energy of the steam flow leaving the turbine is E4, and there is an energy loss of dEf, there is also an energy loss of dq. Are dEf and dq internal energy from the system?
May 14, 2018 · I know shaft work in is expressed as $$ \int v dp $$ In a turbine with fluid in at P1 and V1, and fluid out at P2 and V2, the fluid 1 exerts pressure on the turbine blades equal to P1. The blades must then exert pressure back such that P_blades+P2 = P1. As the fluid undergoes expansion over the blades, it does boundary work $$\int p dv $$
So a simple substitution allows equation 2 to be re-written as equation 3. S = (U - W)/T. Equation 3 This alternate form of the equation works for heat taken out of a system (U is negative) or work done on a system (W is negative), just as well. So now we have a better idea of the classical relation between work, energy and entropy.
Oct 1, 2017 · If so, then you know that (1) the focus of the closed system version is on the working fluid (2) the focus of the open system version is the equipment through which the working fluid is flowing, (3) the open system version splits the work into shaft work and work to force fluid into or out of each piece of equipment, and (4) that the two ...
