a) Explain the variation of work per cycle of reciprocating compressors which compress the air in a polytrophic process with the variation of expansion index (n) from 1 to 1.4 (Use the p-v diagram for comparison). b) Consider a reciprocating compressor with no clearance volume. The temperature and the pressure of start of the compression process is T and pi respectively. After the compression the pressure is increased up to p2. Prove that the work per cycle of the compressor using p-V diagram. (compression is according to law pvn= constant, total mass of air at the end of suction is m) - (1) (mRT) () W = P I. II. (n-1) c) A reciprocating air compressor takes in air at 1.013 bar and 25C and compresses it according to law pv1.3= constant. Then it is delivered to a receiver at a constant pressure of 10 bar. R=0.287 kJ/kg K. Determine: Temperature at the end of compression. Work done per kg of air. a) Prove Bernoulli's equation for the adiabatic process. b) A gas with a velocity of 300 m/s is flowing through a horizontal pipe at section A where pressure is 78 kN/m absolute and temperature 40 C. The pipe changes in diameter at section B, at this section the pressure is 117 kN/m absolute. Find the velocity of the gas in section B if the flow of the gas is adiabatic. (y=1.4) a) Describe the usage of combustion in a thermodynamic perspective by stating real-world applications. b) Calculate the A/F ratio of a sample of dry coal that has the following composition by mass, C= 74%, H=6%, O=13%, N=1.5%, S-0.75%, and Ash=4.75%. (molar mass C-12 g/mol, H=1 g/mol, O=16 g/mol, S-32 g/mol, N=14 g/mol)