Steam at 10 MPa , 600 ° C enters the first - stage turbine of an ideal Rankine cycle with reheat . The steam leaving the reheat section of the steam generator is at 500 ° C , and the condenser pressure is 6 kPa . If the quality at the exit of the second stage turbine is 90 % , determine the cycle thermal efficiency .
In: Mechanical Engineering
PLEASE READ THIS CAREFULLY FIRST BEFORE ANSWERING!!!!!! A DOWN VOTE WILL BE GIVEN IF YOU JUST PASTE AN ANSWER WITHOUT JUSTIFYING IT LIKE I'M ASKING FOR.
I know this question is already on here but i have seen too many differing answers for a) and ultimately b) & c) so i am after justification for your answer that you provide. The main answers i have seen for a) are 35955.4 Kg/Hr and 44398.3 Kg/Hr dependant on which side they put the 0.9. Again please justify why you put the 0.9 on the side you do.
For b) i have seen 2 differing answers also of 1134.8 and 619 depending on if they convert to Kelvin or not. Again please explain why if you do or don't do so.
a) Dry sat steam at 180 degrees is to be produced in a fire tube boiler from the cooling of 50000 kg h-1 of flue gases from a pressurised combustion process. the gases enters the tubes of the boiler at 1600 degrees and leave at 200 degrees. The feed water is externally pre-heated to 180 degrees before entering the boiler.
The specific heat capacity of the flue gases is 1.15 kj kg-1 k-1
The latent heat of vapourisation of the water at 180 degrees is 2015 kj kg-1
Feed water temp 180 degrees.
Determine amount of steam produced per hour, if total heat loss is 10 percent of the heat available for steam raising.
b) The overall heat transfer coefficient based on the outside area of the tubes is given as 54 Wm-2K-1. Determine the area of heat transfer required to perform this duty
c) The tubes within the boiler are to be 25 mm inside diameter with a wall thickness of 3 mm. The average flue gas velocity through the tubes to maintain the overall heat transfer coefficient value and to minimise pressure losses is to be more than 22 m s–1 and less than 28 m s–1 .
Assuming that the average density of the flue gases is 1.108 kg m–3 , calculate:
i) the minimum and maximum number of tubes in each pass
ii) the overall length of tubes at each of these numbers of tubes
iii) the minimum number of tube passes in each case, if the length of a boiler tube is to be less than 5 metres.
In: Mechanical Engineering
1) The flow rate of a liquid which is discharged by a pump is given by Q and the head is given by H. The specific gravity of the liquid which has a standard unit of kg/m2.s2, is denoted by SG. Using dimensional analysis, find the expression for pumping power (P) for this machine.
2) An axial pump has a rotor diameter of 32 cm. The pump
discharges water (ρwater = 1000 kg/m3) at a rate of 2.5 m3/min
while rotating at 1450 RPM. The energy input to the pump is 120
J/kg and the overall efficiency is 78%. If a scale model of this
pump has a rotor diameter of 22 cm and rotates at 2900 RPM,
calculate:
(i) flow rate of water in the model pump;
(ii) change in total pressure from the model pump; and
(iii) input power to the model pump.
In: Mechanical Engineering
The filtration is carried out for 15 min at a constant rate in a leaf filter and continued at constant pressure using a cake that is incompressible with a filter medium resistance that is negligible. This pressure is that attained at the end of the constant rate period. The volume collected during the constant rate period = volume collected at constant pressure, what is the total filtration time?
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Cold air at temperature of 10 C and velocity of 3 m/s is moving parallel to a flat plate with the length of 6 m and surface temperature of 75 C. A) Find the transition location on the plate and the heat loss from the plate. B) Repeat part (A) for water at the same velocity and temperature. The flat plate is made from copper.
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ENGINEERING HEALTH AND SAFETY
Describe the possible sources of dangers and the respective areas involved.
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• How close to an edge can a Rockwell Test be made?
• Discuss conversions of hardness testing values.
• A Rockwell HRB92 is equivalent to a Brinell hardness using a 500 kg force with a 10 mm ball of?
In: Mechanical Engineering
In: Mechanical Engineering
The fully-developed, steady,Poiseuilleflow of a liquidina horizontal, circular cylinderwith no swirl (i.e., Vθ= 0)under certain simplifying assumptions is given by:
Vz = (−∆???)4?(R2 –r2)Vr = 0Vθ= 0Here, Ris the inner radius of the pipe and r, θand zare the (cylindrical) coordinates of any point inside the pipe.Apply the continuity equation in cylindrical coordinates (Appendix B.8 of the text), given by()()()0zr1rrr1t=+++zrVVVto this flow (giving reasons why you drop each term) and obtain an ordinary differential equation for Vr. Integrate your solution and apply appropriate boundary conditions to obtain Vr.
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Engineering Health, Safety and Environment
List (with appropriate examples) of the following:
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The mechanism shown is for a transfer conveyor. The driving link rotates counterclockwise at a constant rate of 25 rpm, and the box has a mass of 10 kg as shown. The mass of the driving link and the coupler are negligible. Conveyor friction is adequate to prevent box slipping in the position shown. The mass of the conveyor link is 15 kg and the center of gravity is at its midspan. The mass moment of inertia of the conveyor link relative to the center of gravity is 4 kg-m2. For β = 30֠, graphically determine the following:
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A piston‑cylinder device initially contains 0.2 m3 of helium at 100 kPa and 25C. The helium is then compressed during a polytropic process (Pvn = constant). The final pressure is 270 kPa and the final temperature is 150C. Determine (a) the mass of the helium (kg), (b) the final volume (m3), (c) the poly tropic exponent n, (d) the work for the compression process (kJ), and (e) the heat transfer (kJ).
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An aluminum alloy cylinder (2) is clamped between rigid heads by
two steel bolts (1), as shown. The steel [E = 200 GPa;
α1 = 11.7 × 10−6/°C] bolts
have a diameter of 20 mm. The aluminum alloy [E = 70 GPa;
α2 = 23.6 × 10−6/°C] cylinder has an
outside diameter of 145 mm and a wall thickness of 7 mm. Assume
that a = 625 mm, b = 735 mm, and c = 375
mm. If the temperature of this assembly changes by ΔT =
95°C, determine
(a) the normal stress in the aluminum cylinder.
(b) the normal strain in the aluminum cylinder.
(c) the normal strain in the steel bolts.
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One of the major impacts of a large scale wind farm is the visual impact. Describe the visual impacts that can arise from large scale wind farms, methods of quantifying these and ways of mitigating them.
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A steel part made from AISI 1050 is to be cooled from austenite temperature to the room temperature;
(a) draw the micro-structures step by step during cooling to room temperature;
calculate the total amount of (b) ferrite, (c) cementite, (d) pearlite
this is urgent please
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