Ask question

Ask question

All categories

3 years ago

15

A fuel cell vehicle draws 50 kW of power at 70 mph and is 40% efficient at rated power. You are asked to size the fuel cell syst

em so that a driver can go at least 400 miles at 70 mph before refueling. Specify the minimum volume and weight requirements for the fuel cell system (fuel cell fuel tank): Fuel cell power density is 1.5 kW/L and 1 kW/kg (note: the values taken into account efficiency already). Fuel tank energy density (compressed hydrogen with the tank mass taken into account): 4 MJ/L and 8 MJ/kg.

1 answer:

svetoff [14.1K]3 years ago

4 0

Answer:

a) fuel cell weight and volume: 50 kg, 33.3 L

b) fuel tank weight and volume: 321 kg, 643 L

Explanation:

<u>Fuel Cell</u>

Delivery of 50 kW from a source with a power density of 1.5 kW/L requires a source that has a volume of ...

(50 kW)/(1.5 kW/L) = 33.3 L

The weight of the power source is 1 kW/kg, so will be ...

(50 kW)/(1 kW/kg) = 50 kg

__

<u>Fuel Tank</u>

400 miles at 70 mph will take (400/70) h ≈ 5.71429 h. In that time, the energy used by the vehicle power plant is ...

(50 kW)(5.71429 h)(3600 s/h) = 1028.57 MJ

Since the power plant is 40% efficient, it must be supplied with 2.5 times that amount of energy, or 2571.43 MJ.

The tank volume and mass will then be ...

volume = 2571.43 MJ/(4 MJ/L) = 642.9 L

mass = 2571.43 MJ/(8 MJ/L) = 321.4 kg

_____

<em>Comment on fuel tank volume</em>

It appears the fuel tank would need to be equivalent in size to a sphere about 1.1 m in diameter.

You might be interested in

A rigid tank contains an ideal gas at 40°C that is being stirred by a paddle wheel. The paddle wheel does 240 kJ of work on the

Sergeu [11.5K]

To solve the problem it is necessary to consider the concepts and formulas related to the change of ideal gas entropy.

By definition the entropy change would be defined as

$\Delta S = C_p ln(\frac{T_2}{T_1})-Rln(\frac{P_2}{P_1})$

Using the Boyle equation we have

$\Delta S = C_p ln(\frac{T_2}{T_1})-Rln(\frac{v_1T_2}{v_2T_1})$

Where,

$C_p$ = Specific heat at constant pressure

$T_1$ = Initial temperature of gas

$T_2$ = Final temprature of gas

R = Universal gas constant

$v_1$ = Initial specific Volume of gas

$v_2$ = Final specific volume of gas

According to the statement, it is an isothermal process and the tank is therefore rigid

$T_1 = T_2, v_2=v_1$

The equation would turn out as

$\Delta S = C_p ln1-ln1$

<em>Therefore the entropy change of the ideal gas is 0</em>

Into the surroundings we have that

$\Delta S = \frac{Q}{T}$

Where,

Q = Heat Exchange

T = Temperature in the surrounding

Replacing with our values we have that

$\Delta S = \frac{230kJ}{(30+273)K}$

$\Delta S = 0.76 kJ/K$

<em>Therefore the increase of entropy into the surroundings is 0.76kJ/K</em>

8 0

3 years ago

When the Moon is in the position shown, how would the Moon look to an observer on the North Pole?

kirill115 [55]

Answer:

cant see the moon sorry dude

5 0

3 years ago

Write a statement that calls the recursive method backwardsAlphabet() with parameter startingLetter.

Tcecarenko [31]

Recursion refers to the act of calling a function itself. With the use of this strategy, complex problems can be reduced to more manageable, simpler ones. Recursion might be a little challenging to comprehend. The best method to figure out how it works is to experiment with it.

<h3>How to write a programme by recursive method ?</h3>

The process of making a function call itself is known as recursion. With the use of this strategy, complex problems can be reduced to more manageable, simpler ones. Recursion might be a little challenging to comprehend. Experimenting with it is the most effective way to learn how it functions.

public class Recursive Calls {

public static void backwards Alphabet(char currLetter) {

if (currLetter == 'a') {

System.out.println(currLetter);

}

else {

System.out.print(currLetter + " ");

backwards Alphabet(--currLetter);

}

return;

}

public static void main (String [] args) {

char starting Letter = '-';

starting Letter = 'z';

// Your solution goes here

backwards Alphabet(starting Letter);

return;

}

}

To learn more about recursive method refer to :

brainly.com/question/24167967

#SPJ4

6 0

1 year ago

Can a 1½ " conduit, with a total area of 2.04 square inches, be filled with wires that total 0.93 square inches if the maximum f

Papessa [141]

Answer:

it is not possible to place the wires in the condui

Explanation:

given data

total area = 2.04 square inches

wires total area = 0.93 square inches

maximum fill conduit = 40%

to find out

Can it is possible place wire in conduit conduit

solution

we know maximum fill is 40%

so here first we get total area of conduit that will be

total area of conduit = 40% × 2.04

total area of conduit = 0.816 square inches

but this area is less than required area of wire that is 0.93 square inches

so we can say it is not possible to place the wires in the conduit

4 0

3 years ago

The temperature of a system rises by 10 °C during a heating process. Express the rise in temperature of K, R, and °F.

Lorico [155]

Explanation:

Given T = 10 °C

The conversion of T( °C) to T(K) is shown below:

T(K) = T( °C) + 273.15

So,

T = (10 + 273.15) K = 283.15 K

<u>T = 283.15 K </u>

The conversion of T( °C) to T(F) is shown below:

T (°F) = (T (°C) × 9/5) + 32

So,

T (°F) = (10 × 9/5) + 32 = 50 °F

<u>T = 50 °F</u>

The conversion of T( °C) to T(R) is shown below:

T (R) = (T (°C) × 9/5) + 491.67

So,

T (R) = (10 × 9/5) + 491.67 = 509.67 R

<u>T = 509.67 R</u>

6 0

3 years ago