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3 years ago

Explain the difference in the heat transfer modes of conduction and convection.

Engineering

1 answer:

LiRa [457]3 years ago

4 0

Explanation:

Conduction is the heat transfer through a stationary matter by the physical contact.

For example, the heat transferred between electric burner of stove and bottom of pan is transferred by the process of conduction.

Convection is heat transfer by macroscopic movement of the fluid. The particles of the fluid carry the current within themselves.

For example, the water is the pot is warmed overall by heat transferred by the process of convection.

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g A smooth pipeline with a diameter of 5 cm carries glycerin at 20 degrees Celsius. The flow rate in the pipe is 0.01 m3/s. What

earnstyle [38]

Answer:

The friction factor is 0.303.

Explanation:

The flow velocity ( $v$ ), measured in meters per second, is determined by the following expression:

$v = \frac{4\cdot \dot V}{\pi \cdot D^{2}}$ (1)

Where:

$\dot V$ - Flow rate, measured in cubic meters per second.

$D$ - Diameter, measured in meters.

If we know that $\dot V = 0.01\,\frac{m^{3}}{s}$ and $D = 0.05\,m$ , then the flow velocity is:

$v = \frac{4\cdot \left(0.01\,\frac{m^{3}}{s} \right)}{\pi\cdot (0.05\,m)^{2}}$

$v \approx 5.093\,\frac{m}{s}$

The density and dinamic viscosity of the glycerin at 20 ºC are $\rho = 1260\,\frac{kg}{m^{3}}$ and $\mu = 1.5\,\frac{kg}{m\cdot s}$ , then the Reynolds number ( $Re$ ), dimensionless, which is used to define the flow regime of the fluid, is used:

$Re = \frac{\rho\cdot v \cdot D}{\mu}$ (2)

If we know that $\rho = 1260\,\frac{kg}{m^{3}}$ , $\mu = 1.519\,\frac{kg}{m\cdot s}$ , $v \approx 5.093\,\frac{m}{s}$ and $D = 0.05\,m$ , then the Reynolds number is:

$Re = \frac{\left(1260\,\frac{kg}{m^{3}} \right)\cdot \left(5.093\,\frac{m}{s} \right)\cdot (0.05\,m)}{1.519 \frac{kg}{m\cdot s} }$

$Re = 211.230$

A pipeline is in turbulent flow when $Re > 4000$ , otherwise it is in laminar flow. Given that flow has a laminar regime, the friction factor ( $f$ ), dimensionless, is determined by the following expression:

$f = \frac{64}{Re}$

If we get that $Re = 211.230$ , then the friction factor is:

$f = \frac{64}{211.230}$

$f = 0.303$

The friction factor is 0.303.

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igomit [66]

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2 years ago

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gogolik [260]

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2 years ago

A long corridor has a single light bulb and two doors with light switch at each door. design logic circuit for the light; assume

sattari [20]

Answer and Explanation:

Let A denote its switch first after that we will assume B which denotes the next switch and then we will assume C stand for both the bulb. we assume 0 mean turn off while 1 mean turn on, too. The light is off, as both switches are in the same place. This may be illustrated with the below table of truth:

A B C (output)

0 0 0

0 1 1

1 0 1

1 1 0

The logic circuit is shown below

C = A'B + AB'

If the switches are in multiple places the bulb outcome will be on on the other hand if another switches are all in the same place, the result of the bulb will be off. This gate is XOR. The gate is shown in the diagram adjoining below.

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3 years ago

"Write a statement that outputs variable numItems. End with a newline. Program will be tested with different input values."

kirill [66]

Answer:

The solution code is written in Java.

System.out.println(numItems);

Explanation:

Java println() method can be used to display any string on the console terminal. We can use println() method to output the value held by variable numItems. The numItems is passed as the input parameter to println() and this will output the value of numItems to console terminal and at the same time the output with be ended with a newline automatically.

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3 years ago