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Oksi-84 [34.3K]
2 years ago
13

1. A team of students have designed a battery-powered cooler, which promises to keep beverages at a high-drinkability temperatur

e of 36°F while outside is 100°F. If the insulation leaks heat at a rate of 100 Btu/h, calculate the minimum electrical power required, in Watts. If we use USB-charged 5 V batteries, what is the minimum battery size needed, in Amp-hours, if the cooler is supposed to work for 4 hours?
Engineering
1 answer:
Anit [1.1K]2 years ago
6 0

Answer:

Minimum electrical power required = 3.784 Watts

Minimum battery size needed = 3.03 Amp-hr

Explanation:

Temperature of the beverages, T_L = 36^0 F = 275.372 K

Outside temperature, T_H = 100^0F = 310.928 K

rate of insulation, Q = 100 Btu/h

To get the minimum electrical power required, use the relation below:

\frac{T_L}{T_H - T_L} = \frac{Q}{W} \\W = \frac{Q(T_H - T_L)}{T_L}\\W = \frac{100(310.928 - 275.372)}{275.372}\\W = 12.91 Btu/h\\1 Btu/h = 0.293071 W\\W = 12.91 * 0.293071\\W_{min} = 3.784 Watt

V = 5 V

Power = IV

W_{min} = I_{min} V\\3.784 = 5I_{min}\\I_{min} = \frac{3.784}{5} \\I_{min} = 0.7568 A

If the cooler is supposed to work for 4 hours, t = 4 hours

I_{min} = 0.7568 * 4\\I_{min} = 3.03 Amp-hr

Minimum battery size needed = 3.03 Amp-hr

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Answer:

Explanation:

From the given information:

Water freezing temp. T_L = 32 ^0 \ F

Heat rejected temp T_H = 72 ^0 \ F

Recall that:

The coefficient of performance is:

COP_{ref} = \dfrac{T_L}{T_H - T_L} \\ \\  = \dfrac{32+460}{(72 +460) -(32+460)} \\ \\ =\dfrac{492}{532 -492} \\ \\ = \dfrac{492}{40} \\ \\ COP_{ref} = 12.3

Again:

The efficiency given by COP can be represented by:

COP = \dfrac{Q_L}{W} \\ \\ W = \dfrac{Q_L}{COP} \\ \\ W = \dfrac{2000 \ lbm \times 144 \ Btu/lbm}{12.3} \\ \\ W = 23414.63 \ Btu

Finally; the power input in an hour can be determined by using the formula:

Power= \dfrac{W}{t} \\ \\  Power = \dfrac{23414.63 \ Btu}{ 1 \ hr} \\ \\  Power = \dfrac{23414.634 \times 1055.056 \ J}{1 \times 3600} \\ \\  Power  = 6.86 \ kW

In hp; since 1 kW = 1.34102 hp

6.86kW will be = (6.86 × 1.34102) hp

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2 years ago
Suppose you are asked to design an office building. Explain what type of drawing you would use and why.
ohaa [14]

Answer:

birds-eye view perspective

Explanation:

If someone asked me to design an office building, I would draw it from a birds-eye view perspective. I would draw it this way so I could map out where everything in the office would go and make sure I have enough space for everything. I would also draw it this way in order to clearly see where everything would go in the office. For instance, cubicles/desks could go in the bottom left corner, while the boss's office could go in the top right. It would be easier to organize and it would be easier for me to look back on when I need to actually design the office later.

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2 years ago
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Answer:

The force induced on the aircraft is 2.60 N

Solution:

As per the question:

Power transmitted, P_{t} = 8 kW = 8000 W

Now, the force, F is given by:

P_{t} = Force(F)\times velocity(v) = Fv               (1)

where

v = velocity

Now,

For a geo-stationary satellite, the centripetal force, F_{c} is provided by the gravitational force, F_{G}:

F_{c} = F_{G}

\frac{mv^{2}}{R} = \frac{GM_{e}m{R^{2}}

Thus from the above, velocity comes out to be:

v = \sqrt{\frac{GM_{e}}{R}}

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where

R = R_{e} + H

R = \sqrt{GM_{e}(\frac{T}{2\pi})^{2}}

where

G = Gravitational constant

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R is calculated as 42166 km

Now, from eqn (1):

8000 = F\times 3075.36

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Answer:

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Explanation:

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