Category: Gas Power Cycles

The comparison parameters selected are: Figure 9.14 Comparison for equal compression ratio and heat input:(a) p-v diagram, (b) T-s diagram Figure 9.17 Comparison for equal compression ratio and heat rejection: (a) p-v diagram, (b) T-s diagram Example 9.1 A Carnot cycle has lowest temperature and pressure of 20°C and 1 bar. The pressures are: 4 bar after…

The air standard Brayton or Joule cycle is a constant pressure cycle used in gas turbine power plants. The p-v and T-S diagrams are shown in Fig 9.12. It consists of the following processes: 1−2: Isentropic compression in the compressor 2−3: Constant pressure heat addition. 3−4: Isentropic expansion of air 4−4: Constant pressure heat rejection Consider 1 kg of working…

In the dual cycle, part of the heat is supplied at constant volume and the rest at constant pressure. This is also called mixed or limited pressure cycle. The p–v and T–s diagrams are shown in Fig. 9.10. The various processes are: Process 1−2: Isentropic compression of air Process 2−3: Constant volume heat addition Process 3−4: Constant pressure heat addition…

This cycle is used for compression ignition internal combustion engines working on diesel oil. The p-v and T-s diagrams are shown in Fig. 9.8. It consists of four internally reversible processes two adiabatic, one constant pressure and one constant volume. The various processes are: Process 1–2: Isentropic compression of air. Process 2–3: Heat addition at constant pressure. Process 3–4: Isentropic expansion of air.…

This cycle is composed of four internally reversible processes, two adiabatic and two constant volume processes. The p-v and T-s diagrams are shown in Fig. 9.6. The various processes are: Process 1−2: Isentropic compression. Process 2−3: Constant volume heat addition. Process 3−4: Isentropic expansion. Process 4−1: Constant volume heat rejection. This cycle is used for spark ignition (petrol) engines. Consider 1 kg of air…

This cycle has two reversible adiabatics (isentropics), one isobar and one isochore. The p-v and T-s diagrams are shown in Fig. 9.5. For one kg of the working fluid, we have Heat supplied, qs = cv (T3 – T2) Heat rejected, qr = cp (T4 – T1) Net work done, wnet = qs − qr = cv (T3 −T2) − cp (T4 −T1) Thermal efficiency,  where  Let compression ratio,  Explosion ratio,  From compression process 1 − 2, we have For constant volume heat addition…

This cycle also works on the principle of regeneration. It consists of two reversible isothermals and two reversible isobars. The p-v and T-s diagram are shown in Fig. 9.4. The heat rejected during the heat rejection process 4 – 1 at constant pressure is stored in the regenerator and the same is supplied during heat addition process 2 – 3.…

This cycle works on the principle of regeneration by using a regenerator within the engine itself which would store the rejected heat energy during heat rejection process and supply the same during heat addition process. The Stirling cycle consists of two reversible isotherms and two reversible isochors. The p − v and T − s diagrams are shown in Fig.…

The Carnot cycle consists of two reversible isotherms and two reversible adiabatics, as shown in Fig. 9.2. For one kg of gas (T1 > T2), we have Figure 9.2 Carnot cycle: (a) p-v diagram, (b) T-s diagram Heat supplied,  Heat rejected,  Net work, 

The piston-cylinder arrangement is shown in Fig. 9.1. The various definitions are: Bore (d): is the cylinder or piston diameter. Stroke (L): is the distance moved by the piston in one direction. It is equal to twice the crank radius. Figure 9.1 Piston-cylinder arrangement Top Dead centre (T.D.C.): is the extreme position of the piston near to the head of…