# Tag Info

58

The whole point of lubrication is to keep the two surfaces almost apart. Water has low viscosity in comparison to oil-based lubricants, which means that it forms a thinner film (electrohydrodynamic film thickness) between the two surfaces; the thinner the film, the greater the chance of direct physical contact between the parts. So, the higher viscosity ...

31

The exhaust gasses are compressible fluids, whereas liquid water is not. Here's an animation of how a gas turbine works: https://www.youtube.com/watch?v=gqNtoy2x5bU At the combustion stage, the gas and compressed air are mixed together, already at high pressure. The burning releases the energy stored in the gas, heating up the released gasses (exhaust). ...

30

Because most of the water is at the lowest point is can be, the ocean. Second issue is that you need quite a bit of vertical drop for water power to be a viable power source. There are DIY hydro power setups but they include diverting part of a stream through a pipe into a turbine down the hill, but those tend to only be enough to power a single household ...

13

Sea water is about the worst thing in the world to put in a metallic mechanical device. As noted , corrosion would be horrendous ; dissimilar metals, stray currents , etc. Wind turbine gearing is an exceptionally demanding application ; EP ( extreme pressure ) lubes are needed with graphite and/or moly sulfide, etc. I am sure a major problem addressed by ...

11

There are two issues, harnessing and market. You need both to be viable. A market, makes most of the 70% of the land mass covered by water unusable, because even if you could harness the power, it is impossible to get the power to consumers. There are no practical storage alternatives, either. Ocean buoys do harness ocean currents to meet their ...

8

Rivers in a flat landscape are often unsuitable because you need a height difference to make the turbine work. Let's say a 1 meter height difference is required. There are many areas where the river's gradient is so shallow that raising the river's level by 1 meter would inundate everything for miles around, so you'd need to build a dam to contain the river. ...

7

In more developed areas (cities) burying streams is popular because it allows for more land to be developed without the fear of flooding. Also, streams in these areas tend to become very blighted and void of life. At that point you might as well hide them from sight. The area that you show doesn't seem to be one of these areas. There are a few reasons that I ...

7

Well liners are generally made to order. One of your issues will be to find a company that can make what you want. You will need to ensure the liner is the correct size and that it does not tear when inserted into the well, while being filled with water, or when it is being removed from the well. You mention your wells are cased with concrete pipes. They ...

7

Even if you had matching orifices, you might have issues with the pressure drop inside the pipes and corners. If you are really after matching flow rates, you could look into flow control valves/flow regulator.

6

What's missing so far is an explanation why you can't expand from high pressure to atmospheric in a single stage gas turbine. There are two types of gas turbines - impulse and reaction turbines. Both face the same problem but it's easier to understand in the impulse turbine. An impulse turbine accelerates the gas through a nozzle from high pressure P1 to a ...

6

The density depends not only on temperature, but also on salinity, see the wikipedia page on seawater, which has this neat diagram: Assuming you have seawater of constant salinity, you can use the above graph to get your answer by drawing a vertical line at the corresponding salinity value. The intersections of that line with the lines of equal density will ...

5

Carnegie, through their CETO device, and others have already looked at using wave power to directly pressurise water for reverse osmosis: a wholly mechanical process rather than converting to electricity and back again (giving potential efficiency savings). Two challenges: first, there aren't many places in the world with a really huge wave resource (UK, ...

5

I see two ways: I've had great experience in my pressure vessel design with a 2.3 mm thick liner of polypropylene or polyethylene. In a pinch, you can weld PVC, but I don't recommend it. Thinner stuff works as well, but the 2.3 mm allows you to place a weld bead on the edge using standard weld rod and plastic welding tools. If not, for a pretty ...

5

What's the reason for going to the cost and effort of doing this? In many places, placing a stream into a culvert can be cheaper in the long run. Streams (particularly fast flowing ones) erode the land and may require erosion protection added in the future. An advantage is reduced land use: Land that does not have a stream running through it can be used ...

5

Great question! Water absolutely is used as a lubricant in some power generating systems. For example many Francis style turbines use their feed water as the primary lubricant and coolant of the bottom main bearing. (In the old Loeffel turbines, that bearing was typically made of lignum vitae wood, and could last up to 100 years in near constant use). ...

4

Yes, Underground Detention is a thing. That Wikipedia article even mentions placing them under parking lots. The exact method that you propose is a little different than preconstructed vaults, but it is the same in the end. Pervious concrete on top of gravel with voids serves the same purpose but with much lower capacity. It is not really speeding up the ...

4

If you have horizontal water flow (no head) you are extracting its kinetic energy (from its velocity) not its potential energy (from its head). So you need to know the velocity of that flow as well as the flow rate to calculate the energy available. (You can calculate it from the flow rate and channel dimensions) You cannot extract all the available ...

4

The best method is to pressurize your tank on the upper floor, then regulate the flow as it goes down. This is because pressurizing will require active components (i.e. pumps, and other devices that you do not want to run continuously, or they will cost money while not in use). Once the tank has 40 psi of pressure, a water pressure regulator at each floor, ...

4

In years past I would have been a fan of hydroelectric power but I have read1 about some of the downsides over the years. These include: Major ecological problems including blocking fish migration. Putting in fish ladders or stairs doesn't really work well as the fish can't find them with all the din of the spillways and turbines. Most silt up drastically ...

3

It isn't just a question of air. When you put suction on a system that's normally under pressure, you're going to draw in contaminants through every available opening — leaks in underground pipes, garden hoses left in buckets, heating systems, etc. Generally a very bad idea.

3

The reason why a hydroelectric generator is fundamentally different to a gas turbine is because water under pressure is not a gas, and does not change size significantly as energy is extracted from it. A gas engine has to account for considerable thermal and volume changes of the gases inside the engine, so multiple parts and multiple materials are ...

3

Water turbines are a major source of electric power. A water turbine generally has only one rotor disk. (from Old Moonraker at Wikipedia) Gas turbines are used in natural gas electric power generators, jet aircraft, and a few other vehicles. A gas turbine generally have lots of rotor disks, which can be divided into two groups: compressor rotor disks and ...

3

You could use the Equation of State for seawater. Sources and detailed information on this topic are to be found here, here and here. Please note that the equation apparently does not cover temperatures below freezing point. Equation of State for Seawater $(\rho - \rho^0) = AS_A + BS^{1.5}_A + CS^2_A$ $\rho^0$ is the densitiy of pure water. With \$A = ...

3

Considering that reverse osmosis is not the only way to desalinate water, I think that yes, there is a lot of development potential in desalination, but that potential might not lie in improvements to existing techniques. To justify this conclusion and illustrate some areas where there could be a lot of development potential, I present to you my idea for a ...

3

Water is going to have to leave the turbine at a speed. That what you've referred to as its residual mechanical power. The thing is, the turbine has already slowed down the water as much as can reasonably be done, while still allowing the water to leave the plant and not flood it. So slowing it down further with an extra stage of turbine just isn't an option....

3

Static water level refers to the level of water (in a well for example) under normal, undisturbed, no-pumping conditions. Static water level is best determined when the well has not been pumped for several hours prior to measuring. You may get a false reading if the well was pumped just before the static water level is measured. Water Table Level is The ...

3

I would describe this negative incline portion of the pond as a "shelf". They are common and need to be self-supporting with a material that has compression and tensile strength; concrete and rebar, rock, fiberglass, etc. There are lots of examples of this: covered irrigation canals dam water turbine intakes water diversion intakes zoo habitats natural ...

3

I was part of a team of contractors to remove and spread the dried sediment from a water treatment facility - the sediment was a red cake/ powder and was spread on the fields as fertiliser.

3

They are merely ornamental. Near the top of the image you can see the base of Juche Tower (Google Maps), a monument in Pyongyang on the bank of the Taedong river. (the two large fountains are curiously not visible in this picture, though) A DPRK tourism website states the following (emphasis mine): The Juche Tower was built on the occasion of the 70th ...

3

If the head pressure is any more than just adequate, the problem is very easy. Just ensure that the bottleneck is near the points of exit, that they are of equal diameter and approximately the same elevation. If those conditions are met the flow rate will be very nearly identical among the outlets, regardless of the configuration and lengths of pipe leading ...

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