Q1. Q1. A fluid contained in a cylinder receives 150 kJ of mechanical energy by (a) means of a paddle wheel, together with 50 kJ in the form of heat. At the same time, a piston in the cylinder moves in such a way that the pressure remains constant at 200 kN/m^2, during the fluid expansion from 2 m3 to 5 m3. What is the change in internal energy and in enthalpy?
() (a) means of a paddle wheel, together with 50 kJ in the form of heat. If required, apply first law to compute ΔU and ΔH.
()
(b) Consider a chilled-water pipe of length L, inner radius r1, outer radius r2 and thermal conductivity k. Water flows in the pipe at a temperature Tf and the heat transfer coefficient at the inner surface is 'h'. If the pipe is well insulated on the outer surface, express the differential equation and the boundary conditions for
(i) steady one-dimensional heat conduction through the pipe; obtain a relation for the variation of temperature in the pipe
(ii) solve the differential equation.
()
(c) Briefly describe the following non-petroleum based liquid fuels used in IC engines:
(i) Benzol
(ii) Vegetable oils
(iii) Alcohol
(iv) Acetone
() (d) Explain in detail the influence of any four factors on the volumetric efficiency of an automotive IC engine.
() (e) A 40 cm long, 800 W electric resistance heating element with diameter 0.5 cm and surface temperature 120°C is immersed in 75 kg of water initially at 20°C. Determine how long it will take for this heater to raise the water temperature to 80°C. Also, determine the convection heat transfer coefficients at the beginning and at the end of the heating process.
