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3 years ago

“Convection is equal to the Conduction plus fluid flow.”

Engineering

1 answer:

zysi [14]3 years ago

8 0

Answer:

Conduction is the transfer of heat by contact, mostly in solids (metals especially) . In conduction, the molecules of the body in contact with the hot body vibrates about a fixed point. The vibration causes collision between these vibrating molecules and their neighboring molecule, causing them to vibrate too; creating a wave of vibrating molecules that transfer the heat along the solid material.

Convection is the transfer of heat in fluids (liquids and gases), that involves the initial heat transfer between a portion of the fluids molecules and the hot body (conduction) at the thermal boundary, and then the eventual movement of that portion of the fluid from that position to a colder part of the fluid. The heated fluid is replaced by a colder fluid (this is due to buoyant forces due to difference in density of the cold and the warm parts of the fluid). This movement ensure thorough mixing of the fluid and the eventual heating up of the entire fluid.

From the above statements one can clearly see that convection is comprised of an initial heat transfer by conduction at the thermal boundary, followed by movement of the fluid molecules.

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A light pressure vessel is made of 2024-T3 aluminum alloy tubing with suitable end closures. This cylinder has a 90mm OD, a 1.65

Andru [333]

Given:

Outer Diameter, OD = 90 mm

thickness, t = 0.1656 mm

Poisson's ratio, $\mu$ = 0.334

Strength = 320 MPa

Pressure, P =3.5 MPa

Formula Used:

1). $Axial Stress_{max}$ = $P[\frac{r_{o}^{2} + r_{i}^{2}}{r_{o}^{2} - r_{i}^{2}}]$

2). factor of safety, m = $\frac{strength}{stress_{max}}$

Explanation:

Now, for Inner Diameter of cylinder, ID = OD - 2t

ID = 90 - 2(1.65) = 86.7 mm

Outer radius, $r_{o}$ = 45mm

Inner radius, $r_{i}$ = 43.35 mm

Now by using the given formula (1)

$Axial Stress_{max}$ = $3.5[\frac{45^{2} + 43.35^{2}}{45^{2} - 43.35^{2}}]$

$Axial Stress_{max}$ = $3.5\times 26.78$ =93.74 MPa

Now, Using formula (2)

factor of safety, m = \frac{320}{93.74} = 3.414

7 0

3 years ago

(1) Estimate the specific volume in cm3 /g for carbon dioxide at 310 K and (a) 8 bar (b) 75 bar by the virial equation and compa

ludmilkaskok [199]

Answer:

70.66 cm^3

The specific volume for P = 70.66 is within 1% of the experimental value while the viral equation will be inaccurate when the second viral coefficient is used )

Explanation:

Viral equation : Z = 1 + Bp + Cp^2 + Dp^3 + -----

Viral equation can also be rewritten as :

Z = 1 + B ( P/RT )

B ( function of time )

Temperature = 310 K

P1 = 8 bar

P2 = 75 bar

<u>Determine the specific volume in cm^3 </u>

V = 70.66 cm^3

<u>b) comparing the specific volumes to the experimental values </u>

70.58 and 3.90

The specific volume for P = 70.66 is within 1% of the experimental value while the viral equation will be inaccurate when the second viral coefficient is used )

attached below is the detailed solution

3 0

2 years ago

Consider the cascade of the three LTI systems having impulse responses: h-1(t) = e^-tu(t + 3) h_2(t) = rect((1 -1)/2) h_3(t) = d

omeli [17]

Explanation:

There are two ways to find out the equivalent impulse response of the system.

1. Convolution in time domain

2. Simple multiplication in Laplace domain

2nd method is efficient, easy and is less time consuming.

Step 1: Take the Laplace transform of the given three impulse response functions to convert time domain signals into s-domain

Step 2: Once we get signals in s-domain, multiply them algebraically to get the equivalent s-domain response.

Step 3: Take inverse Laplace transform of the equivalent impulse response to convert from s-domain into time domain.

Solution using Matlab:

Step 1: Take Laplace Transform

Ys1 = 1/(s + 1)

Ys2 = 1/s - exp(-s/2)/s

Ys3 = exp(-3*s)

Step 2: Multiplication in s-domain

Y = (exp(-(7*s)/2)*(exp(s/2) - 1))/(s*(s + 1))

Step 3: Inverse Laplace Transform (Final Solution in Time Domain)

h = heaviside(t - 7/2)*(exp(7/2 - t) - 1) - heaviside(t - 3)*(exp(3 - t) - 1)

8 0

3 years ago

A 0.9% solution of NaCl is considered isotonic to mammalian cells. what molar concentration is this?

natka813 [3]

Answer:

58.44 g/mol The Molarity of this concentration is 0.154 molar

Explanation:

the molar mass of NaCl is 58.44 g/mol,

0.9 % is the same thing as 0.9g of NaCl , so this means that 100 ml's of physiological saline contains 0.9 g of NaCl. One liter of physiological saline must contain 9 g of NaCl. We can determine the molarity of a physiological saline solution by dividing 9 g by 58 g... since we have 9 g of NaCl in a liter of physiological saline, but we have 58 grams of NaCl in a mole of NaCl. When we divide 9 g by 58 g, we find that physiological saline contains 0.154 moles of NaCl per liter. That means that physiological saline (0.9% NaCl) has a molarity of 0.154 molar. We can either express this as 0.154 M or 154 millimolar (154 mM).

3 0

3 years ago

Explain about Absolute viscosity, kinematic viscosity and SUS?

ArbitrLikvidat [17]

Answer:

Absolute viscosity is the evaluation of the resistance (INTERNAL) of the fluid flow

Kinematic viscosity relates to the dynamic viscosity and density proportion.

SUS stands for Sabolt Universal Seconds. it is units which described the variation of oil viscosity

Explanation:

Absolute viscosity is the evaluation of the resistance (INTERNAL) of the fluid flow, whereas Kinematic viscosity relates to the dynamic viscosity and density proportion. fluid with distinct kinematic viscosities may have similar dynamic viscosities and vice versa.Dynamic viscosity provides you details of power required to make the fluid flow at some rate, however kinematic viscosity shows how quick the fluid moves when applying a certain force.

SUS stands for Sabolt Universal Seconds. it is units which described the variation of oil viscosity when change with change in temperature. it is measured by using viscosimeter.

3 0

3 years ago