Mechanical Engineering Answers

A rigid tank contains air at 1.5 bar and 600C. The pressure of air is raised

to 2.5 bar by transfer if heat from a constant temperature reservoir at

4000C. The temperature of the surroundings is 270C. Determine per kg of

air, the loss of available energy due to heat transfer.

A reheat cycle with one stage of reheating is executed with steam initially from 90 bar and

530 C. The reheater pressure is 10 bar and the steam leaves the reheater at 480 C.

Condensation occurs at 0.03 bar. find a) W and Wp, b) Heat added, c) Heat rate of the engine

The diameter of an open-topped tank 1.5 m high increases uniformly from 4.2 m at the [20] base to 6 m at the top. Discharge from the base of the tank takes place through a

75 mm diameter pipe which is 3 m in length. The pipe discharges the water to the atmosphere 1.5 m below the base of the tank. Initially, the tank is fully filled with water.

Take ƒ = 0.01. Find the time to empty the tank.

In a steady flow apparatus, 250 k} of work is done by each kg of the fluid. The specific volume of the fluid, pressure and speed at the inlet are 0.37m*/kg, 600 kPa and 16 m/s. The inlet is 32 m above the floor under the discharge pipe is at lour level. The discharge conditions arc 0.62 m*/kg, 100 kPa and 270 m/s. The internal energy decreases from 100 k/kg to S0 k/kg. How much heat in kJ kg is added to the system? (15 points)

3. For a certain ideal gus R = 25.8 d k = 1.09 What is the value of c, in points) You sent b.What rass (in lb) of this gas would occupy a volume of 15 eu ft at 75 psia and 80 degrees Fahrenheit? points) f 30 BTU are transferred to thais gas at constant volume in (bj, what is the resulting temperature in degrees Fahrenheit? (1 BTU-778 ft h An adiabatic expansion of air occurs through a nozzle from 828 kPa and 71 degrees Celsius to 138 kPa. The initial kinetic energy is negligible. Far an isentropic expansion compile the speed the (5 points) exit section (1S peints)

One kilogram of gas at an initial pressure of 0.11 MN/m² and a temperature of 15⁰C.

It is compressed isothermally until the volume becomes 0.1 m³. Determine

a) the final pressure

b) the final temperature

c) the heat transfer

If the compression had been adiabatic, determine

d) the final pressure

e) the final temperature

f) the work transfer

For the gas, take c_p = 0.92 KJ/kg K c_v = 0.66 KJ/kg K

The center rod CD of the assembly shown in the figure is heated from T₁ = 30^oC to T₂ = 180^oC using electrical resistance heating. The two end rods AB and EF are heated from T₁ = 30^oC to  T₂ = 50^oC. At the lower temperature T₁, the gap between C and the rigid bar is 0.7 mm. Rods AB and EF are made of steel and each have a cross-sectional area of 125 mm². CD is made of aluminum and has a cross-sectional area of 375 mm². E_Steel = 200 GPa, E_Aluminum = 70 GPa,    α_steel = 12x10^-6/^oC, α_Aluminum = 23 x10^-6 /^oC.

Calculate the force and the stress in rods AB, EF and CD caused by the increase in temperature.