The cylinder C is being lifted using the cable and pulley system shown.

For problems 1 and 2, six luminaires, similar to Style E used in the Commercial Building, are to be installed in a room that is

BlackZzzverrR [31]

Answer:

7ft (2.13 m).

Explanation:

From the question above, the following parameters/data are given; the room dimension = 12 ft × 18 ft (∼3.7 m × ∼5.5 m), the floor-to-ceiling height = 9 ft (2.8 m) and the spacing ratio for the luminaire is 1:0.

Note that, we are not given the value or data for the height of the plane, therefore, we will make an assumption that the height of the plane = 2ft.

Hence, the work plane to luminaire distance = (9 - 2)ft = 7ft (2.13 m).

So, the maximum distance that the luminaires can be separated and achieve uniform illuminance is;

= the work plane to luminaire distance × spacing ratio for the luminaire.

= 7ft (2.13 m) × 1 = 7ft (2.13 m).

Thus, the maximum distance that the luminaires can be separated and achieve uniform illuminance is 7ft (2.13 m).

6 0

3 years ago

The minimum fresh air requirement of a residential building is specified to be 0.35 air changes per hour (ASHRAE, Standard 62, 1

Natalka [10]

We know that

$A=200m^2\\h=2.7m\\\upsilon= 5.5m/s\\\%_{air} = 35%$

So, the volume of the entire building is

$V=2.7*200 = 540m^3$

The flow capacity of the fan

$\dot{V} = \frac{0.35*540}{60}$

$\dot{V} = 3.15m^3/min$

As $1L=10^{-3}m^3,$

$\dot{V}=3150L/min$

For the other part we know

$\dot{V}=\frac{\pi d^2}{4}V$

The diameter is,

$d=\sqrt{\frac{4\dot{V}}{\pi V}}$

$d=\sqrt{\frac{4*3.15}{\pi* 5.5* 60}}$

<em>**Note 60 is for the minutes</em>

$d= 0.1101m$

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4 0

3 years ago

11–17 A long, thin-walled double-pipe heat exchanger with tube and shell diameters of 1.0 cm and 2.5 cm, respectively, is used t

lana [24]

Answer:

the overall heat transfer coefficient of this heat exchanger is 1855.8923 W/m²°C

Explanation:

Given:

d₁ = diameter of the tube = 1 cm = 0.01 m

d₂ = diameter of the shell = 2.5 cm = 0.025 m

Refrigerant-134a

20°C is the temperature of water

h₁ = convection heat transfer coefficient = 4100 W/m² K

Water flows at a rate of 0.3 kg/s

Question: Determine the overall heat transfer coefficient of this heat exchanger, Q = ?

First at all, you need to get the properties of water at 20°C in tables:

k = 0.598 W/m°C

v = 1.004x10⁻⁶m²/s

Pr = 7.01

ρ = 998 kg/m³

Now, you need to calculate the velocity of the water that flows through the shell:

$v_{w} =\frac{m}{\rho \pi (\frac{d_{2}^{2}-d_{1}^{2} }{4} )} =\frac{0.3}{998*\pi (\frac{0.025^{2}-0.01^{2} }{4}) } =0.729m/s$

It is necessary to get the Reynold's number:

$Re=\frac{v_{w}(d_{2}-d_{1}) }{v} =\frac{0.729*(0.025-0.01)}{1.004x10^{-6} } =10891.4343$

Like the Reynold's number is greater than 10000, the regime is turbulent. Now, the Nusselt's number:

$Nu=0.023Re^{0.8} Pr^{0.4} =0.023*(10891.4343)^{0.8} *(7.01)^{0.4} =85.0517$

The overall heat transfer coefficient:

$Q=\frac{1}{\frac{1}{h_{1} }+\frac{1}{h_{2} } }$

Here

$h_{2} =\frac{kNu}{d_{2}-d_{1}} =\frac{0.598*85.0517}{0.025-0.01} =3390.7278W/m^{2}C$

Substituting values:

$Q=\frac{1}{\frac{1}{4100}+\frac{1}{3390.7278} } =1855.8923W/m^{2} C$

5 0

4 years ago

Derive an expression for the axial thrust exerted by a propeller if the thrust depends only on forward speed, angular speed, siz

seropon [69]

Answer:

Find the given attachment

6 0

4 years ago

True or False: Stress can effectively be relieved through physical activity, getting enough rest and sleep, and relaxation techn

Neko [114]

Answer:

True

Explanation:

Actually this are some of the nitty gritty answers and ways to control or stip stress, lemme explain them you see stress most of the time may come from deep thoughts that are and are pushing you to the wall, and you in your state you as you react to that which is so demanding as it makes you tense,so if at you will incorporate physical activities like running, jogging or push ups the psychological tension in you is broken as you focus so much on the activities rather than the tension, then getting enough rest cools the mind and all your thoughts settle as in your brain starts to adapt to chilling and relaxation and enough sleep will actually make ones head to be at peace because if you lack enough sleep you might have an excruciating migraine when you are stressed up and finally relaxation techniques makes the body accept the situation and then you manouver out of it as you grow strongly.

Hope this will help!

7 0

3 years ago

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