>> Mechanical Engineering
Thermodynamics Assignment -
Problem 1 - A vertical piston-cylinder assembly containing a gas is placed on a hot plate. The piston initially rests on stops and has a mass of 50 kg, while atmospheric pressure is Patm = 101.325 kPa. Let the area of the piston be A = 0.01 m2 and assume that gravity is g = 9.81 m/s2.
a) At what pressure, in kPa, will the piston begin to rise?
b) Assume the piston rises 10 cm. If the amount of work done by the gas equals the change in total energy of the piston, how much work has been done, in J?
Problem 2 - A reservoir is used to generate electricity via a turbine-generator, as shown below. Let the height be h = 100 m while volume flow rate through the turbine is V· = 100 m3/s. Assume that the density of water is ρ = 1000 kg/m3, gravity is g = 9.81 m/s2, that the velocity at points 1 and 2 are negligible and both points are exposed to atmospheric pressure.
a) What is the maximum possible specific energy production potential, in J/kg, of this setup?
b) Given the information, what is the maximum power production of the system, in MW?
c) If the output of the generator is 13.5 kV, what is the resulting amperage, in A?
Problem 3 - a) The summation of all microscopic energies of a system, such as internal kinetic, the latent energy, the chemical energy, and the nuclear energy, is also called what type of energy?
b) What forms of energy can cross the boundary of an open thermodynamic system?
c) What is the equation for the power produced by a shaft rotating at n· revolutions per second?
d) Does an adiabatic process need to be isothermal? Provide an example demonstrating your answer.
e) It takes 2.079 J of work to stretch a spring from 1 mm to 10 mm. What is the spring constant, in kN/m?
1. Print this document one-sided. Write solutions on this document.
2. Include your name and the section (A-E).
3. Write all solutions on this document.
4. Be sure to write legibly and show all work.
5. Points will be deducted for any non-professional behavior such as not including your name, not stapling sheets, and writing illegibly.