# A Brief Explanation of Engineering Thermodynamics

CHENNAI

DEPARTMENT OF MECHANICAL ENGINEERING

113301 – ENGINEERING THERMODYNAMICS

UNIT – 1 : ASSIGNMENT QUESTIONS

1. A piston and cylinder machine contains a fluid system which passes through a complete cycle of four processes. During a cycle, the sum of all heat transfers is -170kJ. The system completes 100 cycles per min. Complete the following table showing the method for each item, and compute the net rate of work output in kW.

|Process |Q (kJ/min) |W (kJ/min) |∆E (kJ/min) | |a-b |0 |2,170 |- | |b-c |21,000 |0 |- | |c-d |-2,100 |- |-36,600 | |d-a |- |- |- |

(P.K.Nag Pg.No.66)

2. Air at 1.02 bar, 22ᵒC, initially occupying a cylinder volume of 0.015 m3 is compressed reversibly and adiabatically by a piston to a pressure of 6.8 bar. Calculate : (i) the final temperature, (ii) the final volume & (iii) the work done. (Ans: T2=507.25 K, V2= 0.003869, W=24.513kJ)

3. Air at 30ᵒC and 1 bar is compressed reversibly and polytropically from 5m3 to 1m3 . Calculate the final temperature, pressure and also the work done and heat transfer if the index of compression is 1, 1.4 and 0.9 respectively. Assume Cp=1.005kJ/kgK and Cv=0.7178 kJ/kgK.

4. 2m3 of H2 at a pressure of 1 bar and 20ᵒC is compressed isentropically to 4 bar. The same gas is expanded isothermally restored to o9riginal volume by constant volume heat rejection...

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