Questions tagged [energy]

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24 views

Weibull distribution Units - ENGIEQSOL

I am using Engineering Equation Solver, and it has been telling me the units of my distribution are inconsistent. According to a the book I am reading, I think it should be unitless (as it is a ...
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2answers
55 views

Bernoulli equation on moving cart

Let’s say I have moving cart with velocity U . And water from pipe flows at velocity V with respect to ground The question asks to use Bernoulli equation , pressure is atmospheric in the top If I use ...
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1answer
45 views

Why am I getting wrong value here?

A man threw a ball with force 10 N to two displacement of 5 m and 10 m. F = ma, so let mass be 2 kg. a = 5 m/s2. Work done = 10 × 5 and 10 × 10 = 50 Nm and 100 Nm. Now, since a = 5, I assumed that ...
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1answer
33 views

Can we say kinetic energy is tangential K.E?

I saw this in my textbook that $\dfrac{\text{d}K}{\text{d}t} = \dfrac{\text{d}(1/2mv^2)}{\text{d}t}= F_t v$ where $F_t$ is the resultant tangential force on the body. Now, let $F_t= F\cos\theta$ $$\...
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1answer
34 views

What does the author mean? Turbomachinery - Reaction

I am reading a book of Fundamental Energy Systems. The author describes the rate of change in head for a turbomachine as: $$ \frac{1}{2}[(V_1^2-V_2^2)+(U_1^2-U_2^2)+(V_{R2}^2-V_{R1}^2)] = H =U_1V_{u1} ...
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1answer
26 views

Statistics on energy mix in Europe [closed]

Does anybody know where to find statistics on the energy mix in Europe (preferred by country)? I can only find the share of renewables. I'd like to see the whole mix with a split into energy sources (...
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2answers
38 views

Hydraulic energy recovery for high-pressure, low flow (non-steady state) conditions

What would be the best way to implement hydraulic energy recovery while de-pressurizing a pressurized volume of silicone oil initially at 1500 bar. Can a piston pump be concievably repurposed as a ...
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1answer
52 views

Is oil collapsing [closed]

Oil industry in permain basin is collapsing. Also, no new technology or anything to save it this time. Is this the beginning of the end for oil?
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4answers
4k views

How does turning off electric appliances save energy

We all know if we use less electricity we save energy. But the energy we're getting is result of burning (not necessarily the literal meaning) the fuel. Even if we don't use that energy that fuel is ...
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0answers
30 views

How energy intensive is creating artificial islands in the IJsselmeer?

The City of Amsterdam is building a series of artificial islands for new housing. One of them is Centrumeiland. Its size is 13 ha. (130,000 m2). Its creation requires 800,000 m3 of sand (Source), i.e. ...
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2answers
40 views

Why do some metals with bcc structure show ductile-brittle transition in charpy impact test?

I was learning about the charpy impact test and came across the graph on this webiste that shows the impact energy for bcc and fcc structures as a function of temperature. I tried searching for an ...
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2answers
98 views

How high will a flywheel catapult launch a payload?

First off, this is not a homework question or anything like that. I'm trying to build a catapult to launch a payload using a flywheel as an energy device! It goes like this: The flywheel spins up to ...
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0answers
28 views

Determine Heating costs in $/kWh for a specific location

Suppose I wanted to find the average heating price for a specific location in the US, where: heating_price: The price of equivalent unit energy intensity of heating energy source (e.g. natural gas), ...
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1answer
21 views

Capacity credit vs capacity factor

What is the difference between capacity factor and capacity credit? I know that capacity factor = annual generation / (installed capacity * 8760) but I don't understand how capacity credit is ...
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1answer
49 views

Fluid Mechanics Question

I am preparing for GATE(Chemical). I need the answer of this question part 2 (question 54) as I am not able to find the mistake in my logic. I have applied the logic here as: Initial energy stored in ...
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1answer
45 views

How much time to melt marshmallow under heat lamp?

Using the Specific Heat Formula, I found that I need to apply 612J of heat to melt 18g of marshmallow. Marshmallow has a specific heat of 2 J/(g*C), melting point of 98.6°F, and a starting room ...
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1answer
31 views

Why Do Airborne Wind Energy Systems Use Kites And Not Balloons?

Title says it all, Why are AWE-companies like Makani spending years and millions of dollars developing drones, rather than simply using a balloon-based design? Wouldn't it be easier and faster to get ...
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2answers
46 views

Kinetic energy of a rigid body

A homogeneous disk with radius $R$ and mass $m$ rolls without sliding on a horizontal fixed plane. Peripheral point $A$ has velocity $v$. Determine the kinetic force of the disk. In my textbook they ...
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1answer
27 views

Clothoid Curve / Euler Spiral Energy Transfer

I've seen in an advertisement that Clothoid curves–also known as Euler Spirals–"transfer maximum energy" to a ball bearing that is rolled down it. Firstly, I was wondering if that might be ...
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1answer
52 views

calculating energy usage with measuring the temperature

I am an electrical engineer working on a project. My goal of this project is to make an IoT solution where I continuously measure the temperature of room in a building. I want to calculate the amount ...
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0answers
31 views

Why is the functional of an elastic system equal to it's total potential energy and why is it stationary at it's minimum?

Okay this was even quite difficult to formulate but let's start with some statement's in my FEM book: Elastic continuum has a functional which is equal to it's total potential energy Elastic system ...
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1answer
53 views

Understanding the total energy in a AA battery

AA batteries have about 4 watt-hours (14400 joules, 10620.9 pound-feet). Ignoring losses, does that mean a AA battery could theoretically lift 10,620.9 pounds, 1 foot high? You'd need an electric ...
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0answers
21 views

How do I correctly model this system of torsion springs?

I am currently designing a symmetric parallel mechanism that can be modeled as follows: Here, $\tau^j$ denotes actuator moments and $k_i$ are torsion springs constants. For a specific point in the ...
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0answers
37 views

What are the key technical challenges to development of traveling wave reactors?

I recently learned about traveling wave reactors (TWRs) on the Netflix Bill Gates special, as an example of a cutting-edge technology Gates is funding which has the potential solve several ...
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2answers
318 views

Calculation of the stored energy for a heat storage tank

There is a heat storage tank that is directly loaded from the top and the heat is also taken from the top. The colder water from the heating circuit return flow enters the heat storage tank at the ...
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1answer
31 views

Question about flow temperature and storage temperature in a cogeneration plant

Let's assume I have a cogeneration plant that produces heat with a nominal output. The heat is given into a heat storage tank, which is filled from above. The maximum flow temperature of the ...
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1answer
77 views

Calculation of the specific CO2 emission of a cogeneration plant for the produced electricity

Suppose I have a cogeneration plant that runs on natural gas and produces heat and electricity. The heat effeicieny is $\eta_{th} = 0.4$ and the electricity efficiency is $\eta_{el} = 0.4$. The ...
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2answers
27 views

Uses of orifice in Water Jet Cutting?

I wonder whats the usage of orifice/orifice plate in Water Jet Cutting Machines. To increase pressure(due to a smaller diameter with respect to the entrance cross-sectional area) or to convert to ...
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1answer
38 views

How to estimate wind generation using power curve?

I am trying to verify windfarmer generation estimates manually. To do so I am trying to manually calculate the estimated energy production (kWh) of a wind turbine. The information I have available is ...
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1answer
49 views

Clutch role in a micro hydropower

I've recently visited an old (about 60 years old) micro hydroelectric standalone installation. Total electric power is about 3 kW A/C. A local told me between generator + fly-wheel and turbine there ...
2
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3answers
131 views

Gasturbine energy balance

I have a question regarding gasturbine energy balance, the total energy that flows into the gasturbine is given 12 MW and the power needed for the compressor is 4.4 MW and the turbine power is 9.3 MW....
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0answers
52 views

Enthalpy vs Heat

If we have a closed cylinder filled with a gas and we heat it, by $1^{st}$ law we have: $\Delta q=\Delta U$ (?) since $\Delta V$ = 0. But $\Delta H= \Delta U+ V. \Delta P$. What does that difference ...
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1answer
94 views

What is the difference between a diffuser and a duct in turbines?

I have been reading this paper, which addresses the advantages of diffusers in cross flow turbines. The abstract says (emphasis is mine): A CP’s extraordinary improving resulted when yaw increased ...
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1answer
353 views

Force and Kinetic Energy on a Speed Bump

I have done a basic calculation of the force at an angle on the speed bump when the car makes a contact on it (please check the attached image), now I wanted to calculate the kinetic energy that I can ...
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0answers
70 views

Ideas on optimization of DRA and energy consumption of a pipeline

I have a 200 mile pipeline with a few pump stations in between. I am trying to find ways to optimize the electricity and DRA consumption, and was wondering if anyone has ever done something similar ...
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1answer
515 views

Calculating the Braking Energy of a vehicle

you might find my question stupid. I am unfortunately not an engineer and didn't find the answer on google. I want to calculate the braking energy of a vehicle decelerating from v2 to v1 (km/h). ...
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1answer
486 views

Deriving the equations of motion for free-floating spacecraft with a single link robot arm

Note: I had previously posted this question on the Space and Robotics SE sites, but received little/no response. So I've deleted the previous posts and repasted my question here in the hope of ...
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1answer
54 views

Conductive Heat Transfer calculation over time

I am trying to heat the oil in a 1/2 inch thick rectangular steel box by using an Insulated heated blanket covered on all 6 faces of the box, the working conditions of the operation are at -50 Celsius,...
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1answer
23 views

What are the necessary qualitative criteria for the existence of limit cycles

The literature on the existence of limit cycles is replete with complex and abstract mathematical analysis. Or for specific systems of specific structure, specific mathematical criteria that determine ...
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1answer
174 views

How to convert Joules(kinetic energy) plot chart into watts?

How to convert Joules(kinetic energy) plot chart into watts? Anyone know how?
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1answer
68 views

Converting grams of fuel per kWh of energy

Is there a database showing how many grams of a particular fuel generates how many Kilowatt hours of electricity?
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1answer
56 views

Trying to understand how much it costs to run my clothes dryer

I am trying to calculate the running cost of my clothes dryer and have bought myself an energy meter to check its usage. I plugged the meter in, reset it, and then turned it over to the aggregate kWh ...
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1answer
50 views

Modeling the stiffness of a membrane

I'm trying to model, in MATLAB, a membrane in 2D which has an initial triangle-like shape. This membrane has pressure acting on it from the inside. There are also some pulling forces in random ...
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2answers
46 views

Theoretical maximum generated power for a given torque

Being an electrical engineer, I'm hoping someone will help me double-check my math. I have a small circuit that I want to power for years that consumes an average 10uA at 3V. I'd like to power this ...
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1answer
640 views

What are the differences between compressor stations, pump stations, and booster stations?

I am doing some research on impacts related to natural gas compressor stations. In some states, I've received data for compressor stations alongside other facilities in the oil and gas world. These ...
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1answer
93 views

What are the conditions for a signal to be an energy signal and a power signal?

I know how to find the power and the energy of a signal. What I have a problem with is knowing whether a signal is an energy signal or a power signal. According to my teacher, a signal is a power ...
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2answers
49 views

How do I solve for the mole and mass flow rates in a system?

I've been trying to solve this problem for a while with no success. I think I figured out that $m_1$ is $420 kg/hr$ and that $n_{3,A} = 3 kmol/h$ using the mass balance equation: $input-output+...
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4answers
1k views

Why can't energy be entirely recovered from a moving car's rotating wheels?

I have a friend who isn't properly visualizing energy loss in a moving car. His idea: Cars that can run forever without being recharged - - > while the engine rotates the front wheels the move the ...
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1answer
617 views

Determine the strain energy of a bar

I have a Structures question about determining strain energy that I am unable to solve. I have attempted it and I have the answer, I would appreciate if if someone can just tell me where I am going ...
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1answer
103 views

How do generators in space transmit/ deposit energy back to Earth? [closed]

I've read about the idea of putting solar panels in space, or the already used electrodynamic tethers which gain energy as they move through Earth's magnetic field. The question I have is: How do ...