reversible process workdone111111111.pptx

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1. Air enters a compressor at 10 5 Pa and 25 ° C having volume of 1.8 m3/kg and is compressed to 5 × 10 5 Pa isothermally . Determine : ( i ) Work done ; ( ii ) Change in internal energy ; and ( iii ) Heat transferred

2. Q = ( u 2 – u 1) + W

3. APPLICATION OF FIRST LAW OF THERMODYNAMICS TO NON-FLOW OR CLOSED SYSTEM Reversible Constant Volume (or Isochoric) Process ( v = constant) :

4. Work done and Heat input Q = ( u 2 – u 1) + W The work done W = = 0 as dv = 0. Q = ( u 2 – u 1) = cv ( T 2 – T 1) where cv = Specific heat at constant volume. For mass, m , of working substance Q = U 2 – U 1 = mcv ( T 2 – T 1)  

5. Reversible Constant Pressure (or Isobaric) Process ( p = constant).

6. Work done and heat input Considering unit mass of working substance and applying first law of thermodynamics to the process Q = (u2 – u1) + W The work done, W = = p(v2 – v1) ∴ Q = (u2 – u1) + p(v2 – v1) = u2 – u1 + pv2 – pv1  

7. Work done and heat input cont.. = ( u 2 + pv 2) – ( u 1 + pv 1) = h 2 – h 1 Q = h 2 – h 1 = c p ( T 2 – T 1) h = Enthalpy (specific), and c p = Specific heat at constant pressure. For mass, m , of working substance Q = H 2 – H 1 = m c p ( T 2 – T 1)

8. Enthalpy One of the fundamental quantities which occur invariably in thermodynamics is the sum of internal energy (u) and pressure volume product ( pv ). This sum is called Enthalpy (h). i.e., h = u + pv

9. For a perfect gas, h = u + pv = c vT + RT as [ pv = RT ] = ( c v + R ) T = c pT as [ c p = c v + R ] i.e. , h = c pT and H = m c pT .

10. Reversible Temperature (or Isothermal) Process ( pv = constant, T = constant) : A process at a constant temperature is called an isothermal process. When a working substance in a cylinder behind a piston expands from a high pressure to a low pressure there is a tendency for the temperature to fall. In an isothermal expansion heat must be added continuously in order to keep the temperature at the initial value. Similarly in an isothermal compression heat must be removed from the working substance continuously during the process

11. Workdone ? Heat input?

12. Reversible Adiabatic Process ( pv γ = constant) : An adiabatic process is one in which no heat is transferred to or from the fluid during the process. Such a process can be reversible or irreversible. The reversible adiabatic non-flow, process will be considered in this section. Considering unit mass of working substance and applying first law to the process Q = ( u 2 – u 1) + W O = ( u 2 – u 1) + W or W = ( u 1 – u 2) for any adiabatic process

13. Workdone ? Heat input?

14. Arya Saha 20:00 Arya Saha Satyajit Bera 20:00 Satyajit bera Satyam Paul 20:00 Satyam paul dibhas singha 20:00 Dibhas singha Ratnadeep Roy 20:00 Ratnadeep Roy CHANDAN KUMAR JHA 20:00 Chandan Kumar Jha Avishek Das Gupta 20:00 Avishek Das Gupta Supriyo Naskar 20:00 Supriyo Naskar Puspita Das 20:00 Puspita Das Souvik Chakraborty 20:00 Souvik Chakraborty Samyak Chatterjee 20:00 Samyak Chatterjee vignesh arumaidurai 20:00 Vignesharumaidurai souvik khan 20:00 Souvik khan Purnendu Pattanayak 20:00 Purnendu Pattanayak TARUN BISWAS 20:01 Tarun Biswas PARTHA NASKAR 20:01 PARTHA Naskar Harsh Kumar 20:02 Harsh Kumar