Questions tagged [power-engineering]
74 questions
22
votes
4 answers
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 gone forever. (Except saving money on bills)
My…
ShivCK
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15
votes
2 answers
Quantifying inertia on the electricity grid
A lot of discussion about the modernisation of electricity systems is about "inertia". This is usually a qualitative discussion about how turbines (in hydro, coal & gas plants) with lots of kinetic energy in the form of angular momentum and fast…
410 gone
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14
votes
1 answer
What limits a power plant's load gradient?
Each power plant has a load gradient characteristic, describing to what extent it can change the output of its generators in a given timeframe. Reading the literature, I know that, for example, a gas turbine power plant has a vastly higher load…
Technaton
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13
votes
3 answers
How to correctly size the blades for a small educational wind turbine?
I want to design a small wind turbine that can be easily carried out of the classroom into the sports field in relatively low-wind conditions (5-15km/h) that can power a small ultra-bright 5V LED - just enough to show that it works.
How do I…
jhabbott
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8
votes
7 answers
Why do electric trains arc at high speeds?
When I watch videos of high speed trains I always see explosions of electricity near the top, or arcing. Why does that happen? I know that the Acela does it a lot but other high speed trains have it, too.
user3831089
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7
votes
2 answers
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 bottom. This creates a layered water temperature in…
Emma
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5
votes
2 answers
How is the shift map of an automatic transmission constructed?
Figure 2 in this tutorial represents the shift map/schedule of an automatic transmission. How is this map constructed? I want to know how to design a shift map myself for another transmission.
The shift map is below:
Karlo
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5
votes
1 answer
What is the difference between an automatic transmission and an automated manual transmission?
What is the difference between an automatic transmission (AT) and an automated manual transmission (AMT)?
Karlo
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5
votes
1 answer
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 burning of natural gas produces 215 g/kWh of CO2.
For…
Emma
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5
votes
2 answers
Advantages/Disadvantages of two-bladed windmill?
The vast majority of wind turbines I have ever seen feature 3 blades, as shown here:
Recently while driving through western new York state, however, I passed by several turbines featuring only two blades, as shown here:
What advantages and…
Timpanus
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4
votes
2 answers
Advantages of hydrogen gas turbine over fuel cell
In the setting of large-scale electricity generation, I was wondering why one would want to burn hydrogen in a gas turbine instead of using it to power a fuel cell. Aren't fuel cells more efficient because they're not bound by the Carnot limit? Two…
Damian Birchler
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4
votes
4 answers
Why shouldn't we put high voltage cables physically underground?
sorry for the odd title. We're working on a project to find a cheaper and safer way to install high voltage power lines in the Scottish highlands. One of my group mates had a really cool idea to instead of actually digging underground, you could…
masiewpao
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3
votes
6 answers
Working hours of power plant generators
My question might seem a simple one, but it has been troubling me for a while.
How many hours in a day do conventional electrical generators work (the ones in large power plants)?
Do they by any method conserve or store the power before it…
Adnan Arif Sait
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3
votes
4 answers
Why do kWh (smart) meters have a maximum operating altitude?
At first I thought it was a bad translation from Chinese to English, but it turns out that many data-sheets of kWh power meters mention a maximum altitude, usually below 2 or 3 km.
For example:
GoodWe smart meter
Schneider power meter
What exactly…
Louis Somers
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3
votes
3 answers
Efficiency of wireless charging for moving cars
The UK is about to start trials of wireless charging for moving cars.
What kind of power transfer efficiency is likely to be achievable in such a system, compared to just plugging in the car directly?
anon