Answer:
modern vehicles are made to crunch up a little bit so they that absorbe some of the impact instead of you
Explanation:
A fuel oil is burned with air in a furnace. The combustion produces 813 kW of thermal energy, of which 65% is transferred as heat to boiler tubes that pass through the furnace. The combustion products pass from the furnace to a stack at 6500C. Water enters the boiler tubes as a liquid at 200C and leaves the tubes as saturated steam at 20 bar absolute. Calculate the rate (kg/h) at which steam is produced.
The rate at which steam is produced is equal to 701 kg/hour.
What is a Boiler?A Boiler may be characterized as a type of device or instrument that significantly transforms water into steam. There are two types of boiler are found. They are water tube boilers and fire tube boilers.
According to the question,
The power generated by combustion, W = 813kW.
The efficiency of the boiler, η = 65% = 0.65.
Temperature, To = 650°C.
Water enters the boiler tubes as a liquid, T1 = 20°C.
Water leaves the tubes as saturated steam, P2 = 20 bar.
The enthalpy of water at 20°C, [tex]h_1[/tex] = 83.9kJ/kg.
The enthalpy of water at 20 bar pressure, [tex]h_2[/tex] = 2797.29kJ/kg.
Enthalpy change can be calculated by ΔH = [tex]h_2-h_1[/tex]
= 2797.29kJ/kg - 83.9kJ/kg = 2713.3 kJ/kg.
The total energy that can be developed can be calculated by the formula:
Q = W × η = 813 × 0.65 = 528.45 kW.The mass of the flow rate of the rate at which steam is produced is calculated by the following formula:
[tex]m^.[/tex] = Q/ΔH= 528.45 kW/2713.3 kJ/kg.
= [tex]\frac{528.45kW }{2713.3kJ/kg} *\frac{3600kJ/h}{1kW}[/tex] = 701 kg/hour.
Therefore, the rate at which steam is produced is equal to 701 kg/hour.
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A piece of corroded steel plate was found in a submerged ocean vessel. It was estimated that the original area of the plate was 5 in.2 and that approximately 2.3 kg had corroded away during the submersion. Assuming a corrosion penetration rate of 200 mpy for this alloy in seawater, estimate the time of submersion in years. The density of steel is 7.9 g/cm3.
Answer:
the estimated time of submersion is 17.7 years
Explanation:
Given the data in the question;
estimate the time of submersion in years.
we write down the relation between time of submersion and corrosion penetration as follows;
CPR(mpy) = K × W(mg) / [ A(in²) × p(g/cm³) × t(hr) ]
we solve for t
t = (K × W) / ( AP × CPR )
given that;
Area A = 5 in²
W = 2.3 kg = 2.3 × 10⁶ mg
density of steel p = 7.9 g/cm³
CPR = 200
we know that K is 534
so we substitute
t = (534 × 2.3 × 10⁶ mg) / ( 5 in² × 7.9 g/cm³ × 200 mpy )
t = 1,228,200,000 / 7900
t = 155468.3544 hr
t = 155468.3544 hr × ( 1 yrs / ( 365 × 24 hrs )
t = 17.7 years
Therefore, the estimated time of submersion is 17.7 years
The 150 mm thick wall of a gas fired furnace is constructed of fireclay brick (k=1.5 W/m.K) , tho=2600 kg/m3, and cp=1000 J/kg.K ) and is well insulated at its outer surface. The wall is at a uniform initial temperature of 20 degree C, when the burners are fired and inner surface is exposed to products of combustion for which T infinity=950 degree C and h=100 W/ m2.K.
(A) How long does it take for the outer surface of the wall to reach a temperature of 750 degree C?
(B) plot the temperature distribution in the wall at the foregoing time.
Answer:
I am thick but I dont know the anwser
The time that it will take for the outer surface of the wall to reach a temperature of 750 degree C will be 33800 seconds.
How to calculate the time?Using the approximation methods, Fo will be;
= In(0.215/1.262)/(1.4289)²
= 0.867
Then, the time taken will be:
= 0.867(0.15)²/(1.5/2600 × 1000)
= 33800 seconds.
In conclusion, the time taken is 33800 seconds.
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