Calculate the entropy production for the piston-cylinder power producing cycle you analyzed in Problem 1. Consider that all heat flows into the system come from a constant temperature source of 1800K and that all heat flows out of the system are to a constant temperature of 250 K. Will this cycle operate? Which process should be altered in order to improve the efficiency of the system or to make it work?
Problem 1:
. A simple, effective electric load leveling technique is to use excess produced electricity to pump water into a hill top reservoirs during off peak hours and then discharging it during peak electrical demand periods. This simple, old style energy storage concept is increasingly being used to have a more effective power generation system. The drawback to this technique is that one has to operate in a hilly or mountainous region. Someone has suggested an alternative that can be applied at any location. In this alternative, a reclaimed concrete mass is to be raised using excess generated electrical power. The density of the reclaimed concrete is the same as concrete. During excess electrical power production periods, this mass will be raised using a pulley-motor combination. During the peak power demands the mass will be lowered using a pulley-electric generator to produce power. The effect of the friction in the pulley is a tangential force that operates at the outer pulley circumference that interfaces with the cable. This force, Ffric, is proportional to the mass being lifted by the following relationship: Ffric = 0.008(lifted weight) [note: the force is proportional to the weight, a force, not the mass]. There is a similar loss in the cable-winding pulley, but the relationship is Fpulley = 0.003(lifted weight). Frictional losses ultimately are converted to heat losses to the environment. The lifting tower containing this mass has an above ground height limit of 30 m and a below ground depth limit of 30 m. The device can be considered to be isothermal during these processes.
In: Mechanical Engineering
1. Air enters a converging-diverging nozzle with a total pressure of 1100 kPa and a total temperature of 127°C. The exit area to throat area ratio is 1.8. The throat area is 5 cm2. The velocity at the throat is sonic and the diverging section acts as a nozzle. Determine the following:
a. The mass flow rate
b. The exit pressure and temperature
c. The exit Mach number
d. The exit velocity
2. The converging-diverging nozzle now has a throat area of 100 mm2 and an exit area of 160 mm2. The inlet flow is helium at a total pressure of 1 MPa and total temperature of 102°C. Determine the back pressure that will give sonic condition at the throat, but subsonic everywhere else.
In: Mechanical Engineering
What is the lubrication type encountered in worm wheel drives?
a) What is the chief consideration as far as the lubrication requirements for worm wheel drives go?
b) What type of lubricant is recommended for worm wheel drives?
In: Mechanical Engineering
Produce a flowchart to calculate the power performance analysis [Thrust & Torque] of a wind/tidal turbine between the experimental data and theoretical data of a hydrofoil by using Blade Element Momentum Theory. [Hints: polynomial fit and Viterna equations are included in calculation and Power Coefficient (for both exp and theo) vs TSR graph is expected as the result.]
In: Mechanical Engineering
What is MCB (Miniature circuit breaker)?
When a mechanical engineer need this safety device?
In: Mechanical Engineering
Write short note of Productivity through people
In: Mechanical Engineering
(1) [1 Point] True or False: A shock wave is a thin region of highly viscous flow, and the flow through the shock is adiabatic but nonisentropic.
(2) [1 Point] True or False: For hypersonic flow, the ratio of specific heats for air (??) can be assumed to be constant.
(3) [1 Point] True or False: A normal shock wave is a shock wave that makes an oblique angle with respect to the upstream flow.
(4) [1 Point] True or False: The NACA 2412 airfoil has a maximum camber that is less than a NACA 0015 airfoil.
(5) [1 Point] True or False: The critical Mach number is the free stream Mach number at which supersonic flow will occur at a point on the airfoil.
In: Mechanical Engineering
if the condenser fan motor fails and the unit continues to run.. what will happen?
In: Mechanical Engineering
Consider a constant pressure device. The inlet flow to this device is moist air at 100 kPa, 40oC, 40% relative humidity. The outlet flow from this device is cooled to 15oC. Determine:
(a) the humidity ratio of the inlet and the exit flow,
(b) the heat transfer in the device per kg dry air,
(c) repeat (a) and (b) using the psychrometric chart.
In: Mechanical Engineering
For this assignment, you will research the innovation architecture of at least three companies that are well-known for successfully supporting a culture of innovation. Write a 1,500-word paper that addresses the following:
In: Mechanical Engineering
Problem 15.10: Liquid octane (C8H18) enters a steady-flow combustion chamber at 25°C and 1 atm at a rate of 0.35 kg/min. It is burned with 50 percent excess air that also enters at 25°C and 1 atm. After combustion, the products are allowed to cool to 25°C. Assuming complete combustion and that all the H2O in the products is in liquid form, determine (a) the heat transfer rate from the combustion chamber, (b) the entropy generation rate, and (c) the exergy destruction rate. Assume that T0 = 298 K and the products leave the combustion chamber at 1 atm pressure.
In: Mechanical Engineering
design a vapor compression refrigeration system that will maintain the refrigerated space at -15c while operating in an environment at 20c using refrigerant -134a as the working fluid (By EES )please
In: Mechanical Engineering
A neighborhood fuel cell power plant is to be designed for an electric power output of 2000 kW with liquid– water product. Estimate the flow rates of hydrogen and oxygen during peak power production, assuming an 80% efficient power conditioner is used to convert DC to AC power and the fuel cell efficiency is 55%. What is the plant heat rate?
In: Mechanical Engineering
Steam at 1MPa and 0.9 dryness fraction is throttled to a pressure 200kPa.
Find the final state of the steam and the change in entropy during this process.
In: Mechanical Engineering
Engineering Mechanics (7th Edition), Statics, Chapter 2 Problem 27 why are they using the sin rule to calculate angle beta? is it possible to illustrate this in a diagram? Any help would be greatly appreciated
In: Mechanical Engineering