What is the difference between superalloys and high-temperature stainless steel?
In: Mechanical Engineering
What are the materials used in an airplane engine for high-temperature purposes?
Explain the reason for using each material.
In: Mechanical Engineering
What are the most common alloying elements used in stainless steel materials?
What are the effects of each alloying elements on steel?
In: Mechanical Engineering
A squared cross- sectional bar of 3cm by 3cm is under a compressive stress of 300 MPa. The bar deforms elastically, what is the area of the cross section after deformation. Provide your answer in milimeters squared. (Do not type in the unit in your answer.) (E=30GPa, v=0.4)
In: Mechanical Engineering
(Maintenance Engineering) In assigning job priorities, it is important to consider some factors like
In: Mechanical Engineering
Compare and contrast the relative merits and demerits of Reactive maintenance and Predictive maintenance.
In: Mechanical Engineering
Consider the following combined cycle. The mass flow rate of air is 73 kg/s. Air enters the compressor at state 1 with Patm =1 atm and Tamb = 20°C. The compressor has a pressure ratio of 7.5 and an efficiency ?c = 0.85. Air enters the combustor and is heated to a temperature TH = 1250°C. The turbine has an efficiency of ?t,1 = 0.87. The air leaving the turbine enters the steam boiler where it transfers heat to the water in the Rankine cycle. The ratio of the mass flow rate of water in the Rankine cycle to air in the Brayton cycle is 0.1. The water leaving the boiler achieves temperature of 550°C. After boiling the water in the Rankine cycle, the remaining heat left in the Brayton cycle will be used to produce steam for industrial processes. The air enters the steam generator after leaving the boiler and is used to heat water from the inlet state of 5 atm, 20°C to saturated vapor. The temperature of the air leaving the steam generator is 180°C. In the Rankine cycle, the water enters the pump as saturated liquid at 55°C. The pump efficiency is ?p = 0.65 and the exit pressure of the pump is Pboiler = 8.0 MPa. The water enters the heat exchanger (boiler) where it is converted to steam by the heat transfer from the air. The steam turbine has an efficiency of ?t,2 = 0.84. The condenser transfers heat from the water to a river cooling water entering the condenser at Tamb = 20°C. Due to EPA regulations the temperature of the river water at the exit of the condenser cannot be more than 5°C higher than at the inlet.
a.) [20 points] Draw the T-S diagram and the line/component diagram for this combined cycle.
b.) [20 points] Determine all of the state points for this combined cycle. You may consider creating a table including all relevant points with at least the pressure, temperature, entropy and enthalpy.
c.) [10 points] Determine the mass flow rate of steam for industrial purposes produced in the steam generator.
d.) [10 points] Determine the efficiency of the Brayton cycle, the efficiency of the Rankine cycle, and the efficiency of the combined cycle (relative to producing power - do not include the value of the industrial steam that is produced).
e.) [10 points] What is the net power produced by the cycle?
f.) [10 points] If natural gas is used to energize the cycle and the cost of natural gas is NGc = 8$/million Btu determine the yearly fuel cost required to run the plant.
g.) [10 points] Determine the cost associated with producing the same amount of power using a conventional natural gas fired plant with efficiency ?conv = 0.34 and the same amount of steam using a natural gas fired boiler. What are the savings per year associated with using the combined cycle?
h.) [10 points] If natural gas produces 100 lbm of CO2 per million Btu, what is the environmental impact of using the combined cycle versus the conventional natural gas power plant (include power and industrial steam generated).
In: Mechanical Engineering
4-) Given the following data:
Drilling Fluid Density : 12 ppg
Well Depth: 10,000 ft.
Drill Bit Nozzle Sizes: 13-13-13
Pump Horsepower: 1800
Pump Volumetric Efficiency: 80%
Maximum Pump Pressure: 4,500 psi
Minimum Flow Rate: 350 gpm
Parasitic pressure losses of 2,173 psi and 1,388 psi are anticipated while circulating mud at flow rates 500 gpm and 390 gpm respectively.
a-) (10 points) Determine the parasitic pressure losses when the bit hydraulic horsepower is maximum.
b-) ( 5 points) Determine the optimum flow rate when the bit hydraulic horsepower is maximum.
c-) (5 points) Determine the pressure drop across bit nozzles when the bit hydraulic horsepower is maximum.
d-) (5 points) Determine the optimum sizes of three nozzles to be used for the next bit run, using the maximum bit hydraulic horsepower criteria.
In: Mechanical Engineering
In: Mechanical Engineering
2. A Carnot cycle using water as the working fluid operates within the wet region (saturated conditions). If the high pressure for the process is 500 psia and the low pressure is 20 psia, what is the thermal efficiency for the cycle? State your answer as a percent to one decimal place. Example: 32.5
7. In a Rankine cycle steam enters the turbine at 900 psia and 1000oF and exhausts at 1 psia. Determine the heat supplied to the cycle in BTU/lbm.
State your answer to one decimal place. Example: 123.5
I WILL RATE YOU
In: Mechanical Engineering
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