Avertical piston-cylinder device contains nitrogen gas at 2 bar and 0.3 m3 . at this state, a linear spring with a spring constant of 100 kn/m touches the top of the piston but exerts no force on it. the cross-sectional area of the piston is 0.1 m2 . the nitrogen gas is then heated, pushing the piston upwards against the spring, and expands until the volume of the gas doubles show the process on a p-v diagram. b. a determine final pressure (kpa) of the nitrogen gas what is the total work done (kj) during the expansion process? d. what fraction of the total work is done against the spring?

What is the heat treatment of metals? what is the benefit of it? why and how it's useful? answer in details, do not write by hand.

Air flows over a heated plate àt a velocity of 50m/s. the local skin factor coefficient at a point on a plate is 0.004. estimate the local heat transfer coefficient at this point.the following property data for air are given: density = 0.88kg/m3 , viscosity 2.286 x 10 ^-5 kgm/s , k = 0.035w/mk ,cp = 1.001kj/kgk. use colburn reynolds analogy.

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.