Why do engineers play a variety of roles in the engineering process?

Liquid ethanol (C2H5OH) at 298 K, 1 atm enters a steam generator operating at steady state and burns completely with dry air ent

Gennadij [26K]

Answer:

Q= 6491.100 kJ/s

Explanation:

Air-Fuel Ratio:

For a combustion reaction the proportion of air that is present in a gaseous substance responsible for the reaction,this proportion is known as air-fuel ratio.The air fuel ratio is calculated using the combustion reaction for the substance.

Considering reaction for the Ethanol as

C₂H₅OH +XO₂(O₂+3.76N₂)→ aCO₂+bH₂O+cN₂

Balancing the equation we get;

a=2,

2b=6

∴ b=3

xO₂=3

The air-fuel ratio

A/F = XO₂+H₂O+xN₂× mass of N₂/mass(fuel)

3.31×31.9+11.28×28.013/46.069

= 8.943

Equivalent ratio = 0.7,

so, heat transfer

Q= m ×Cp×ΔT

= 75×0.7×112.4(1500-400)

Q= 6491.100 kJ/s

1kJ/s=1000w

∴ Q= 6491100 W

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6 0

4 years ago

A "type 30" brake chamber has a diaphragm diameter of 8" which gives it

Montano1993 [528]

The piston makes four strokes in the crankshaft makes two revolutions between combustion firings. The diameter of the piston, and the inside diameter of the cylinder, is called a bore, so the area of the head of the piston is pi times the diameter squared divided by four.

5 0

3 years ago

In casting experiments performed using a certain alloy and type of sand mold, it took 155 sec for a cube-shaped casting to solid

Tems11 [23]

Answer:

A) Cm = 2.232 s/mm²

B) Time taken to solidify = 74.3 seconds

Explanation:

(A) Since a side is 50mm and all sides of a cube are equal, thus, Volume of the cube is;V = 50 x 50 x 50 = 125,000 mm³

There are 6 faces of the cube, thus Surface Area A = 6 x (50 x 50) = 15,000 mm²

So, Volume/Area = (V/A) = 125,000/15,000 = 8.333 mm

Cm is given by the formula; Cm =[Tts] /(V/A)² where Tts is time taken to solidify and it's 155 seconds in the question. Thus;

Cm = 155/(8.333)²= 2.232 s/mm²

(B) For;Cylindrical casting with D = 30 mm and L = 50 mm.;

Volume of cylinder is;

V = (πD²L) /4

So,V = (π x 30² x 50)/4 = 35,343mm³

Surface area of cylinder is;

A = (2πD²)/4 + (πDL)

Thus, A = ((π x 30²)/2) + (π x 30 x 50) = 6126 mm²

Volume/Area is;

V/A = 35,343/6126 = 5.77 mm

Same alloy and mold type was hsed as in a above, thus, Cm is still 2.232 s/mm²

Since Cm =[Tts] /(V/A)²

Making Tts the subject, we have;

Tts =Cm x (V/A)²

Tts = 2.232 x (5.77)² = 74.3 seconds

3 0

3 years ago

9. To forward bias an NPN transistor, the

murzikaleks [220]

Answer:

a. the base must be more positive than the emitter

Explanation:

A transistor can be defined as a semiconductor component that is used to control the flow of voltage or current and as a gate (switch) for electronic signals. Thus, a transistor allows for the amplification, control and generation of electronic signals in a circuit. The three (3) basic parts of a transistor are; base, emitter and collector.

Basically, there are two (2) main types of transistor and these are;

1. PNP transistor.

2. NPN transistor.

Biasing of a transistor can be defined as the process of providing the controlled amount of direct current (DC) voltage or current conditions so as to enable the transistor amplify the alternating current (AC) input signal correctly.

Hence, to forward bias an NPN transistor, the base must be more positive than the emitter because the majority carriers are electrons which are moved from the n-type region to the p-type region while the minority carriers are holes.

This ultimately implies that, for an NPN transistor to conduct current in milliamps, its base-emitter junction must be forward biased.

4 0

3 years ago

Air at 7 deg Celcius enters a turbojet engine at a rate of 16 kg/s and at a velocity of 300 m/s (relative to engine). Air is hea

Savatey [412]

To solve this problem we will start using the given temperature values and then transform them to the Kelvin scale. From there through the properties of the tables, described for the Air, we will find the entropy. With these three data we can perform energy balance and find the speed of the fluid at the exit, which will finally help us find the total force:

$V_i = 300m/s$