Thermodynamics- Work done- Adiabatic process

In summary, the speaker has a doubt regarding the workdone derivation in an adiabatic process. They provide a derivation using the equation W= (P1V1-P2V2) and note that the textbook uses a different equation, W=Cp(T1-T2). The speaker asks for help in solving this doubt, which they encountered while deriving the Brayton cycle. The expert responds by stating that the first law of thermodynamics in flow systems operating at steady state applies to this situation, and the speaker should review this derivation.
  • #1
kaundinya
2
0
I have a small doubt regarding the workdone derivation in adiabatic process. Here is the derivation
W= (P1V1-P2V2)
= mR(T1-T2)/n-1

AS we know R/n-1 = Cv and Cp/Cv=1 also considering m=1

W=Cv(T1-T2)

but in textbook it is quoted as

W=Cp(T1-T2)


please can u help me in solving this.( i found this during deriving Brayton cycle)
 
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  • #2
kaundinya said:
I have a small doubt regarding the workdone derivation in adiabatic process. Here is the derivation
W= (P1V1-P2V2)
= mR(T1-T2)/n-1

AS we know R/n-1 = Cv and Cp/Cv=1 also considering m=1

W=Cv(T1-T2)

but in textbook it is quoted as

W=Cp(T1-T2)


please can u help me in solving this.( i found this during deriving Brayton cycle)
The adiabatic compression step and the adiabatic expansion step in the Brayton cycle takes place in an open system operating at steady state, with gas flowing through the system. For such circumstances, you need to use the flow form of the first law, which focuses on each parcel of mass flowing through the system. The form of the first law that applies here is Δh=-ws, where Δh is the enthalpy change per unit mass passing through the system, and ws is the shaft work per unit mass. The enthalpy change per unit mass is Cp(T2-T1). You need to go back and review the derivation of the form of the first law that applies to flow systems operating at steady state.

Chet
 
  • #3
thank you
 

1. What is thermodynamics?

Thermodynamics is a branch of physics that deals with the relationships and conversions between heat, work, energy, and other mechanical properties of matter.

2. What is work done in thermodynamics?

Work done in thermodynamics is the transfer of energy from one system to another through the application of a force. This can involve mechanical work, electrical work, or other forms of work.

3. What is an adiabatic process?

An adiabatic process is one in which there is no heat transfer between a system and its surroundings. This means that the energy of the system remains constant, and the only way to change the internal energy is through work done on the system.

4. How is work done in an adiabatic process?

In an adiabatic process, work is done by changing the volume of the system against an external pressure. This can be done by compressing or expanding a gas, for example.

5. What is the first law of thermodynamics?

The first law of thermodynamics states that energy cannot be created or destroyed, only transferred or converted from one form to another. This means that the total energy of a closed system remains constant over time.

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