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An automotive fuel cell consumes fuel at a rate of 28m3/h and delivers 80kW of power to the wheels. If the hydrogen fuel has a heating value of 141,790 kJ/kg and a density of 0.0899 kg/m3, determine the efficiency of this fuel cell.
Answer:
The efficiency of this fuel cell is 80.69 percent.
Explanation:
From Physics we define the efficiency of the automotive fuel cell ([tex]\eta[/tex]), dimensionless, as:
[tex]\eta = \frac{\dot W_{out}}{\dot W_{in}}[/tex] (Eq. 1)
Where:
[tex]\dot W_{in}[/tex] - Maximum power possible from hydrogen flow, measured in kilowatts.
[tex]\dot W_{out}[/tex] - Output power of the automotive fuel cell, measured in kilowatts.
The maximum power possible from hydrogen flow is:
[tex]\dot W_{in} = \dot V\cdot \rho \cdot L_{c}[/tex] (Eq. 2)
Where:
[tex]\dot V[/tex] - Volume flow rate, measured in cubic meters per second.
[tex]\rho[/tex] - Density of hydrogen, measured in kilograms per cubic meter.
[tex]L_{c}[/tex] - Heating value of hydrogen, measured in kilojoules per kilogram.
If we know that [tex]\dot V = \frac{28}{3600}\,\frac{m^{3}}{s}[/tex], [tex]\rho = 0.0899\,\frac{kg}{m^{3}}[/tex], [tex]L_{c} = 141790\,\frac{kJ}{kg}[/tex] and [tex]\dot W_{out} = 80\,kW[/tex], then the efficiency of this fuel cell is:
(Eq. 1)
[tex]\dot W_{in} = \left(\frac{28}{3600}\,\frac{m^{3}}{s}\right)\cdot \left(0.0899\,\frac{kg}{m^{3}} \right)\cdot \left(141790\,\frac{kJ}{kg} \right)[/tex]
[tex]\dot W_{in} = 99.143\,kW[/tex]
(Eq. 2)
[tex]\eta = \frac{80\,kW}{99.143\,kW}[/tex]
[tex]\eta = 0.807[/tex]
The efficiency of this fuel cell is 80.69 percent.
PLEASE ANSWER SOON
In a science lab, Cash mixes two clear liquids together in a beaker. Bubbles are produced, and a white solid forms and settles to the bottom. Which statement below describes what happened?
a
A physical change occurred, a gas and precipitate was produced
b
A physical change occurred, only a gas was produced
c
A chemical change occurred, only a gas was produced
d
A chemical change occurred, a gas and precipitate was produced
Answer:
I think it is D
Explanation:
I did a couple mins of research on this topic but there is no clear line that separates a physical and chemical reaction, so do with that as you will. i hope I somewhat helped.
How do I answer all the questions on this page?
Answer:
Create a google docs copy everything and paste hope this helps! :)
Explanation:
Of the core elements of successful safety and health programs, Management Leadership, Worker Participation, and what else relate to individuals' roles?
Answer:
Education and training I did the TEST and got it right.
Of the core elements of successful safety and health programs, the other one aside the given two that relates to individual roles is;
Education and Training Program.
According to OSHA(Occupational Safety and Health Administration), there are 7 core elements of an effective safety and health program.
These 7 core elements are namely;
1) Management Leadership.
2) Worker Participation.
3) Hazard Identification & Assessment.
4) Hazard Prevention & Control.
5) Education & Training Program.
6) Evaluation & Improvement.
7) Management of Contractors / Staffed Employees.
Now, we have been given 2 of the 7 which are Management leadership and
worker participation. However, we are told to find another one that relates
to individual roles. The only other one that is individual specific is Education
and Training program because it is the responsibility of every staff from top
to bottom to know all about safety.
Read more at; https://brainly.com/question/21555575
The moisture content of a saturated clay is 160 %. The specific gravity of the soil solids Gs is 2.40. What are the wet and dry densities of the saturated clay? hints: what is the degree of saturation of a saturated soil?)
Answer: 162.4
Sorry if you get it wrong :(
Explanation:
Comparing cold working to hot working, flow stress is usually lower in _____ Question 19 options: Cold working Hot working
Answer:
Hot Working
Explanation:
Given that hot working is carried out at temperatures greater than the recrystallization temperature of the metal, thereby the stress needed for deformation is considerably less.
On the other hand, cold working is carried out at temperatures lesser than the recrystallization temperature of the metal, thereby stress needed for deformation is much higher
Hence, comparing cold working to hot working, flow stress is usually lower in HOT WORKING.
Create a story with nuclear engineer (not so long and not so short)
Answer:
I can't write stories well, but I can give character advice!
Explanation:
A really important thing is to make sure your characters act human. In a lot of stories, humans act... well, like aliens or superheroes.Come up with unique traits and descriptions (ex: 2 different colored eyes, spunky, bright orange hair)POV really matters! Choosing the wrong POV might make the character seem to flawed, or too perfect, so POV is one of the most important things in a story!Don't be afraid to make your main character stray from the usual, but make sure there's other characters that stand out, because it gets quite boring if there's only 1 unique character!CAD(computer-aided design) software and is used in__________and __________that show how to construct an object. Technical drawings show in detail how the pieces of something relate to each other.
Answer:
Plans; blueprints.
Explanation:
In Engineering, it is a common and standard practice to use drawings and models in the design and development of various tools or systems that are being used for proffering solutions to specific problems in different fields such as engineering, medicine, telecommunications and industries.
Hence, a design engineer make use of drawings such as pictorial drawings, sketches, or technical drawing to communicate ideas about a design to others, to record and retain informations (ideas) so that they're not forgotten and to analyze how different components of a design work together.
Technical drawing is mainly implemented with CAD (computer-aided design) software and is typically used in plans and blueprints that show how to construct an object.
Additionally, technical drawings show in detail how the pieces of something (object) relate to each other, as well as accurately illustrating the actual (true) shape and size of an object in the design and development process.
Convert 273.15 mL at 166.0 mm of Hg to its new volume at standard pressure.
Answer:
(166.0 mm Hg) (273.15 mL) = (760.0 mm Hg) (x)
1. Drill press size is determined by the largest__
A refrigeration system was checked for leaks. The system temperature and surroundings were 75°F when the system was charged with nitrogen to 100 psig. The temperature then dropped to 50°F. What should the pressure be if no nitrogen has escaped?
A) 9 psig
B) 94 psig
C) 100 psig
D) 90 psig
The temperature and pressure of an ideal gas are directly proportional
The pressure of the system should be in the range B) 94 psig
The given refrigerator parameters are;
The temperature of the system and the surrounding, T₁ = 75 °F = 237.0389 K
The pressure to which the system was charged with nitrogen, P₁ = 100 psig
The temperature to which the system dropped, T₂ = 50 °F = 283.15 K
The required parameter;
The pressure, P₂, of the system at 50°F
Method:
The relationship between pressure and temperature is given by Gay-Lussac's law as follows;
At constant volume, the pressure of a given mass of gas is directly proportional to its temperature in Kelvin
Mathematically, we have;
[tex]\dfrac{P_1}{T_1} = \mathbf{\dfrac{P_2}{T_2}}[/tex]
Plugging in the values of the variables gives;
[tex]\mathbf{\dfrac{100 \ psig}{297.0389}} = \dfrac{P_2}{283.15}[/tex]
Therefore;
[tex]P_2 = \mathbf{283.15 \, ^{\circ}F \times \dfrac{100 \ psig}{297.0389\ ^{\circ}F} \approx 95.3 \, ^{\circ}F}[/tex]
The closest option to the above pressure is option B) 94 psig
Learn more about Gay-Lussac's law here;
https://brainly.com/question/16302261
A ramjet operates by taking in air at the inlet, providing fuel for combustion, and exhausting the hot air through the exit. Th e mass fl ow at the inlet and outlet of the ramjet is 60 kg/s (the mass fl ow rate of fuel is negligible). Th e inlet velocity is 225 m/s. Th e density of the gases at the exit is 0.25 kg/m3 , and the exit area is 0.5 m2 . Calculate the thr
Answer:
15300 N
Explanation:
[tex]\rho_i[/tex] = Density of air at inlet
[tex]\dfrac{m}{t}[/tex] = Mass flow rate = 60 kg/s
[tex]v_i[/tex] = Inlet velocity = 225 m/s
[tex]\rho_o[/tex] = Density of gas at outlet = [tex]0.25\ \text{kg/m}^3[/tex]
[tex]A_i[/tex] = Inlet area
[tex]A_o[/tex] = Outlet area = [tex]0.5\ \text{m}^2[/tex]
Since mass flow rate is the same in the inlet and outlet we have
[tex]\rho_iv_iA_i=\rho_ov_oA_o\\\Rightarrow v_o=\dfrac{\dfrac{m}{t}}{\rho_oA_o}\\\Rightarrow v_o=\dfrac{60}{0.25\times 0.5}\\\Rightarrow v_o=480\ \text{m/s}[/tex]
Thrust is given by
[tex]F=\dfrac{m}{t}(v_o-v_i)\\\Rightarrow F=60\times (480-225)\\\Rightarrow F=15300\ \text{N}[/tex]
The thrust generated is 15300 N.
Assume that Randy’s photocopying Service charges $.10 per photocopy. If fixed costs are
$27000 a year and variable costs are $0.04 per copy.
1. How Randy can compute his breakeven point? Show the result in graph.
2. How many photocopies are required to earn $ 500 profit?
3. Identify the safety margin at breakeven point.
Answer:
1) 739 copies (739.7260273972603).
2) 5000 copies.
Explanation:
27000/365 = 73.97260273972603 (Their daily wins). How much times $.10 is equal to 73.97260273972603?
I used a two step equation to get it.
0.10 * x = 73.97260273972603/0.10 = /0.10 x = 739.7260273972603They need to sell 739.7260273972603 copies a day to get 27000$ a year.
an equation (y = mx+b) can be
y = 739.7260273972603x
To earn a 500$ profit we need to do the same two-step equation but instead of 73.97260273972603 use 500.
0.10 * x = 500/0.10 = /0.10 x = 50005000 copies needs to be sold to get a 500$ profit.
The last question I don't understand but I hope those 2 questions helped
Pyramid is a type of ___________ structure.
Answer:
Massive or linteled
Explanation:
Pyramid is a type of massive or linteled structure.
These structures do no have not much internal spaces and they are huge edifices.
A pyramid is a solid body with outer triangular faces that converges on top. To construct a pyramid, large amounts of materials are usually involved. Pyramids were more prominent in times past before this present civilization.
A 1:50 scale model of a ship is towed at 4.8 km/hr using a force of 9 N. If we assume the same fluid in the model as in the prototype, calculate the corresponding speed and force in the prototype if the flow is dominated by:________. (a) density and gravity (b) density and surface tension (c) density and viscosity (d) Which of the assumptions in (a)-(c) do you think is most appropriate
Answer:
A: density and gravity
Explanation:
The Froude Number is defined as a dimensionless parameter that measures the ratio of the force of inertia on an element of fluid to the weight of the fluid element. In simple terms, it's the force of inertia divided by the gravitational force.
Froudes number is usually expressed as;
Fr = v/√(gd)
Where;
Fr = froude number
v = velocity
g = gravitational acceleration = specific weight/density
d = depth of flow
Now, to calculate the corresponding speed and force in the prototype, it means we have to use equal froude number and thus this will mean that it has to be dominated by gravity and density.
In a movie theater in winter, 510 people, each generation sensible heat at a rate of 80 W, are watching a movie. The heat losses through the walls, windows, and the roof are estimated to be 130,000 Btu/h. Determine the contribution of people to the heating of the building. The average rate of heat generation from people in a movie theater in sensible form is 80 W per person.
Answer:
[tex]139213.68\ \text{Btu/h}[/tex]
Explanation:
Number of people = 510
Heat generated per person with respect to time = 80 W
[tex]1\ \text{W}=3.4121\ \text{Btu/h}[/tex]
Heat generated by 510 people is
[tex]\dot{Q}=510\times 80\times 3.4121[/tex]
[tex]\Rightarrow \dot{Q}=139213.68\ \text{Btu/h}[/tex]
The contribution of people to the heating of the building is [tex]139213.68\ \text{Btu/h}[/tex]
Taking what you have learned about Ohm's law what would the current be through a circuit if the power supply was 110 v and the total resistance on the circuit was found to be 15.2 kiloOhms?
Answer:
7.24 mA
Explanation:
Ohm's law states that the current passing through two points is directly proportional to the voltage across the two points.
V ∝ I
V = IR
R is the resistance which is the constant of proportionality, V is the voltage and I is the current.
Given that V = 110 V, R = 15.2 kΩ
Therefore using ohms law, we calculate the current as:
[tex]V=IR\\\\I=\frac{V}{R}\\\\I=\frac{110}{15.2*10^3}\\\\I=7.24*10^{-3}\\\\I=7.24\ mA[/tex]
Expert Review is done by end users.
Answer:nononononono
Explanation:
