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PostPosted: Sat Mar 11, 2017 8:41 pm 
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Notice, they said slow the erosion. i don't think they have enuf hill to armor and stop the erosion.

And i think we'll be hearing about this in the future.....

https://theconstructor.org/concrete/cav ... tion/8890/
Cavitation damage occurs on concrete surface when discontinuity or irregularities is encountered in the path of high velocity water flow. This discontinuity or irregularity in the flow path cause the water to lift off the flow surface, creating negative pressure zones and resulting bubbles of water vapor. These bubbles travel downstream and collapse. If the bubbles collapse against a concrete surface, it sends a very high pressure impact over an infinitely small area of the surface. Such high pressure impacts can remove particles of concrete, forming another discontinuity which then create more extensive cavitation damage.


The Glen Canyon Dam had the same problem. They almost lost it because of cavitation in 83. The retrofit with aeration slots helped alleviate the problem, but from what i understand so far, does not fully solve the problem.

https://www.usbr.gov/uc/feature/fg/index.html
Cavitation is the formation of partial vacuums or cavities in fast-flowing water which wears away solid surfaces such as concrete, as a result of the collapse of these vacuums. The subsequent repair of the Glen Canyon Dam spillway tunnels included aeration slots which inject air at the base of the water flow to prevent cavitation from occurring.

As a result of the lesson learned at Glen Canyon Dam, Reclamation retrofit other dam spillway tunnels with similar aeration slot designs. The spillway at Flaming Gorge Dam on the Green River in northeastern Utah was modified in the mid-1980’s not long after the Glen Canyon spillway. Although the Flaming Gorge Dam spillway has rarely been used, a periodic inspection of the spillway revealed damage to the concrete in the area where tunnel was modified to install the aeration slot, about four feet above the edge of the aeration slot itself.


Cavitation is what eats the blades off of a ships propellor if the vessel is not ballasted enough to push the prop deep enough under the water and the skipper tries to steam it through the water too fast in that state. It will chew the brass blades right off of the hub in just a few hours.

People don't often understand this but when water is up against a surface it doesn't slide along that surface laterally. It can only move away from that surface, and once it is in the flow it can move back toward that surface as well as laterally. Kind of like molecular feet. All these water molecules marching along the bottom of a waterway, or any other surface in a stream flow.

If extreme pressure tries to force a lateral slipping action on those water molecules touching that surface they become extremely agitated in that toward or away from that surface motion, and in that interaction they do not move amoung themselves in an orderly fashion, like too many people leaving a theater at the same time, too fast, they start shoving each other around. And like in the game of pool the energy from one ball can be transferred to another ball when they collide.

Random collisions of those molecules will have some molecules picking up the energy from several collisions with others additively while others will be drained, it is random. The tussle blows holes in the liquid creating vacuum holes. And in that free vacuum space which is formed those molecules which have picked up additive energy will be traveling very fast. And when those fast travelers hit that surface it pecks away a bit of it like a bullet pecks a hole like pit in any surface it hits. Except that those agated water molecules which picked up additive energy that way can be moving through that free vacuum space at speeds which make flying bullets appear like they are standing still.

That cavated surface will soon be shot so full of microscopic holes it will become nothing but holes. :|

There is a lot about this which when it was studied and was thought about, became the theory Lasers are based upon.


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PostPosted: Sat Mar 11, 2017 10:15 pm 
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A very small amount of water can be expanded into a very large pipe through a hardened orifice. Perhaps one to two thousand cfs. Not enough to make any difference. And the life of the orifice will not be long, as it will be worn away.

Of freeze shut, that kind of unchecked expansion flow will refrigerate and create an ice plug if the orifice is not heated.

Remember how carburetors would sometimes ice in the venturi, and how that would power down the engine on cold foggy days?



Any large release would blow away the powerhouse and open a hole in the bottom of the dam which would cause its collapse. There must be a load.

There is more than that to it too.

That video Bernie posted brings up an issue about the water level outside of the power house, about how the water level of the pool must be below the level of the outlet pipes for the turbines to be able to operate even with a load. That is a superheat issue, the turbines must operate with some degree of superheat. The superheat must never be zero. That is to say there must be some available expansion space at the turbine outlet. If there is none the hydraulic pressures will make some. And that will lift the turbine moving parts part up off of the turbine housing. Then the turbine's blades would strike the housings side and break.

The back pressure caused by the pool level being a bit high wouldn't be much, 5 or 6 psi, one would think it would be overcome by the immense pressure of the height of the dam and the mass of the water, but that little bit of back pressure would be enough at that critical juncture right at the turbine's outlet where it connects to the tube leading out of the powerhouse to deprive the turbines of the superheat it needs to hold together. It would move the superheat from that juncture to the ends of the outlet tubes which is the wrong place for that expansion to be.

This issue comes up in normal refrigeration, occasionally a thermal expansion valve will not operate correctly or a service tech will put too much freon into a system and it will move the superheat from the refrigerator expansion coil all the way through the coil and down the suction pipe leading to the compressor. That means the cooling effect moves from the freezer box to the body of the compressor, so the food doesn't stay frozen, and the compressor drinks liquid instead of gas, and that blows the valves out of the compressor.

Boilers must have superheat as well. There must be space inside of the boiler for water to flash into steam. If they lose the superheat inside of their working vessel they might blow up. It all depends on the pop off valves, it they are large enough they will save the boiler. although some or all of the fire tubes may be lost.

Well it's not so much about the water level as is the amount of debris in the channel to allow a clean flow.
The author of this You Tube channel has been posting regularly on the progress.
www.youtube.com Video from : www.youtube.com

I will note another post that talked about the trucks moving. From this video, it looks like a nice timed line of trucks hauling debris out.

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PostPosted: Sat Mar 11, 2017 11:09 pm 
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It is not that there is one or the other situation Bernie, the two go hand in hand. If there are debris in the channel which do not allow a clean flow, and there is flow it will back up and then it will do what I was talking about. "It will lift the turbine moving parts part up off of the turbine housing. Then the turbine's blades would strike the housings side and break."

The debris pile backed up water from the spillway and initially caused the water level to be high, too high. They very quickly were able to drain that down, but that was not enough, there had to be a sufficient channel of both depth and width opened to allow for the flow from each turbine they brought on line.

Each day the earthmoving deepened and widened the flow channel, and as that work progressed they brought additional turbines online.

I watched the video you posted earlier today and I recommend it. It is part one of a two part discussion regarding the power house and river valves. Today he got all the way through the basic piping features, and with regard to the river valve aspect he mentioned it at 16:04 but did not go into the the energy dissipator ring which lies downstream of the river valves, but upstream of the outlet manifolds. He mentioned it was very important. In part two I hope he goes into depth about that.

That ring keeps the the dam from having a hole blown through its bottom when the river valves are opened. Without that restrictor (energy dissipator) ring if the river valves were opened I would imagine the damage would be such almost instantly that the valves would be unable to be closed.

Every refrigeration system has a restrictor (energy dissipator) ring. Some of them are just a slug of brass with a precision orifice hole drilled through it, others are fancy TXV valves with a needle valve pin which can close off the slug of brass with a precision orifice hole drilled through it.

Without one there is no refrigeration, and the compressor will have its valves knocked out and perhaps even have its crankshaft and rods broken.

I would imagine that when the river valves are used the outlet water temp is lower than the lake water temp feeding it. I looks like the manifold design is to minimize that effect, but don't see how they could minimise all of the refrigeration effect of that system.

So I'm interested to see what Blancolirio's part two research covers about that. Because what I see when I see that river valve assemblage is a gigantic water chiller. I wouldn't be surprised to find out that a substantial amount of natural gas or electrical energy is needed to heat that energy dissipator ring to keep it flowing.


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PostPosted: Sun Mar 12, 2017 8:36 am 
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http://www.mercurynews.com/2017/03/11/o ... ing-wrong/

The first photo. Cavitation?

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PostPosted: Sun Mar 12, 2017 10:47 am 
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http://www.mercurynews.com/2017/03/11/oroville-dam-photos-taken-weeks-before-spillway-broke-show-something-wrong/

The first photo. Cavitation?


Probably not cavitation.

I think a pipe under the slab or in or under the side wall which feeds the side wall water dribblers probably rusted out and created a sinkhole in the fill which undermined the support of one of the sections of the slab, it tipped up or down and then the damage grew.

Notice on the first photo, to the right of the red oval on the far side of the wall in the backfill earth there are two areas which appear to be washed out. The upper wash out appears to be at a higher elevation than that imperfection on the slab they are marking, and the lower washout is even with the mark. And it appears that below that point the water dribbler spaced along that wall is not flowing.

In the second photo they show a longer area of the channel, there is that big hole on the center, but the side walls appear intact, the water dribblers below the break have no flow.

In the third photo, before the breakup of the slab, when they were spilling only small amount showing the pocket of turbulence, that appears to me it may be a case of it sucking air and perhaps water up through a crack from beneath the slab, not cavation.

And in that same photo all of the water dribblers along both walls are not flowing at all. Like maybe they had them turned off because they had realized they had a water supply leak under there somewhere.


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PostPosted: Sun Mar 12, 2017 6:20 pm 
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It is not that there is one or the other situation Bernie, the two go hand in hand. If there are debris in the channel which do not allow a clean flow, and there is flow it will back up and then it will do what I was talking about. "It will lift the turbine moving parts part up off of the turbine housing. Then the turbine's blades would strike the housings side and break."

The debris pile backed up water from the spillway and initially caused the water level to be high, too high. They very quickly were able to drain that down, but that was not enough, there had to be a sufficient channel of both depth and width opened to allow for the flow from each turbine they brought on line.

Each day the earthmoving deepened and widened the flow channel, and as that work progressed they brought additional turbines online.

I watched the video you posted earlier today and I recommend it. It is part one of a two part discussion regarding the power house and river valves. Today he got all the way through the basic piping features, and with regard to the river valve aspect he mentioned it at 16:04 but did not go into the the energy dissipator ring which lies downstream of the river valves, but upstream of the outlet manifolds. He mentioned it was very important. In part two I hope he goes into depth about that.

That ring keeps the the dam from having a hole blown through its bottom when the river valves are opened. Without that restrictor (energy dissipator) ring if the river valves were opened I would imagine the damage would be such almost instantly that the valves would be unable to be closed.

Every refrigeration system has a restrictor (energy dissipator) ring. Some of them are just a slug of brass with a precision orifice hole drilled through it, others are fancy TXV valves with a needle valve pin which can close off the slug of brass with a precision orifice hole drilled through it.

Without one there is no refrigeration, and the compressor will have its valves knocked out and perhaps even have its crankshaft and rods broken.

I would imagine that when the river valves are used the outlet water temp is lower than the lake water temp feeding it. I looks like the manifold design is to minimize that effect, but don't see how they could minimise all of the refrigeration effect of that system.

So I'm interested to see what Blancolirio's part two research covers about that. Because what I see when I see that river valve assemblage is a gigantic water chiller. I wouldn't be surprised to find out that a substantial amount of natural gas or electrical energy is needed to heat that energy dissipator ring to keep it flowing.

And on time Juan Browne has posted the next report in his series...
www.youtube.com Video from : www.youtube.com

And always he gets deeper into the subject. Yes I found the actual blueprints for the Dam structure a great asset for facts when discussing what the problems have been and all of the intricate workings of this dam.

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PostPosted: Sun Mar 12, 2017 7:46 pm 
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His reports are good.

I see something he may not be aware of regarding the river valve use. The river valve assemblage is a refrigeration unit. The valves vent into the upper discharge manifold which two, and sometimes three of the turbines also vent into. That number three turbine appears to be piped to vent into either or both manifolds.

And the problem I see is when the turbines are using that manifold is they fill it, and in order for the river valves to use it, since it needs to expand that water is it needs to not be filled. That discussion about the hurricane winds is telling of that fact. That wall moved subjecting the workers to that wind, that wind would be there on the other side of that wall in any case because it is part of expanding that water, but it usually would not be in that valve chamber if wall were in its proper place. That chamber uses a eductor design sucking that air, literally an air pump, to provide a load to that water flow in order to absorb the excess energy that water contains.

And to add to that I doubt that the river valve is designed to tap that flow when the lake is a full as it is now. Clearly it is designed to take that water from a level at which the turbines cannot operate on down to the bottom. That would be a significant reduction in energy differential for those valves and energy dissipator ring to withstand.

Those winds did supply the missing piece of the puzzle I was looking for. Explaining how they operate without chilling the outlet water to a very low temperature. They supply the heat mass transfer element which supplies the heat to the water which allows the water to expand without greatly affecting the outlet temperature of that discharged water. I.e. not having tce forming and snow falling in summer in and around the outlet pool.

Those river valves raise the hair and hackles on the back of my neck even without adding the complication of having that manifold being used at the same time by the turbine flow. The manifold happens to be there, but it was designed for the turbines, not for the river valves. That the manifold can be used for the river release when the turbines are offline is a serendipitous extra.

If there is any part of the dam design which terrifies me it is those valves. That is because when I look at that design I see a gigantic and overwhelmingly powerful refrigeration device coupled to an insufficient heat transfer load. Trying to generate electricity and expand that water in the same volume would create a backpressure which would more than likely blow the tops off of the turbines. I find the idea of turning both of those systems at the same time simply horrifying.

Open the spillway if they must, don't ever try to use both systems at the same time.


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PostPosted: Sun Mar 12, 2017 8:32 pm 
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His reports are good.

I see something he may not be aware of regarding the river valve use. The river valve assemblage is a refrigeration unit. The valves vent into the upper discharge manifold which two, and sometimes three of the turbines also vent into. That number three turbine appears to be piped to vent into either or both manifolds.

And the problem I see is when the turbines are using that manifold is they fill it, and in order for the river valves to use it, since it needs to expand that water is it needs to not be filled. That discussion about the hurricane winds is telling of that fact. That wall moved subjecting the workers to that wind, that wind would be there on the other side of that wall in any case because it is part of expanding that water, but it usually would not be in that valve chamber if wall were in its proper place. That chamber uses a eductor design sucking that air, literally an air pump, to provide a load to that water flow in order to absorb the excess energy that water contains.

And to add to that I doubt that the river valve is designed to tap that flow when the lake is a full as it is now. Clearly it is designed to take that water from a level at which the turbines cannot operate on down to the bottom. That would be a significant reduction in energy differential for those valves and energy dissipator ring to withstand.

Those winds did supply the missing piece of the puzzle I was looking for. Explaining how they operate without chilling the outlet water to a very low temperature. They supply the heat mass transfer element which supplies the heat to the water which allows the water to expand without greatly affecting the outlet temperature of that discharged water. I.e. not having tce forming and snow falling in summer in and around the outlet pool.

Those river valves raise the hair and hackles on the back of my neck even without adding the complication of having that manifold being used at the same time by the turbine flow. The manifold happens to be there, but it was designed for the turbines, not for the river valves. That the manifold can be used for the river release when the turbines are offline is a serendipitous extra.

If there is any part of the dam design which terrifies me it is those valves. That is because when I look at that design I see a gigantic and overwhelmingly powerful refrigeration device coupled to an insufficient heat transfer load. Trying to generate electricity and expand that water in the same volume would create a backpressure which would more than likely blow the tops off of the turbines. I find the idea of turning both of those systems at the same time simply horrifying.

Open the spillway if they must, don't ever try to use both systems at the same time.

I do not see anything in the building schemes or project diagram stating any refrigeration unit.
https://archive.org/stream/zh9californi ... +thickness
Knowing the gravity fed flow through the closed space would easily evacuate the air from that closed space from the slosh the water makes on it's way down and out of the vent pipes, the air in that cavity is easily allowed to keep it's pressure by having the outside air intake vents clear and open (Pg. 80).

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PostPosted: Sun Mar 12, 2017 8:41 pm 
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I do not see anything in the building schemes or project diagram stating any refrigeration unit.
https://archive.org/stream/zh9californi ... +thickness
Knowing the gravity fed flow through the closed space would easily evacuate the air from that closed space from the slosh the water makes on it's way down and out of the vent pipes, the air in that cavity is easily allowed to keep it's pressure by having the outside air intake vents clear and open.


I wouldn't expect to see that because the river release system is built to release water for the fish. The refrigeration aspect is a by product of physical laws, and one which the design would minimise, if not negate if possible.

I'm a refrigeration expert well versed in thermodynamics and a lifetime of work in the field, I know one when I see one.


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PostPosted: Sun Mar 12, 2017 11:29 pm 
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I wouldn't expect to see that because the river release system is built to release water for the fish. The refrigeration aspect is a by product of physical laws, and one which the design would minimise, if not negate if possible.

I'm a refrigeration expert well versed in thermodynamics and a lifetime of work in the field, I know one when I see one.
Well Sam I am not questioning your knowledge on thermodynamics of the system, simply inserting facts as presented. As far as I can see as well, the water to the fishery is supplied from the Thermalito Forbay dam system and canals, and as you know the generators there (Thermalito) were destroyed by fire, however the forbay is fed by the Feather River (4 miles at least) from the Oroville Dam. I would assume the temperature of the water to be at what is supplied from the Feather River and what water is controlled from the Oroville Dam (lake temperature) supplying the Feather River complex.

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PostPosted: Mon Mar 13, 2017 12:48 am 
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What I'm pointing out is since the lake water is held behind a dam of great height, to release it from the bottom of the dam without a load to absorb the vast pool of energy that water holds, that the thermal aspects of what usually could be ignored with more normal dynamic flow through water works without that elevation factor have to be taken into account.

I saw an energy imbalance, and until I saw how it is dealt with as in the case of the river valves pumping a vast amount of air into the system to deal with the waters expansion I saw a large cooling effect which the law of conservation of energy dictates.

What they have designed to resolve that problem is inducing a reheat after a cooling effect to negate that problem. That induced air flow of warm air carries away much of that cooling effect. Even so I see it as an incomplete solution with limitations, but under the constraints of not operating the valves until the lake is only half full I would imagine that the major problems of the system would be manageable.

I'm doing this without doing calculations on the basis of a lifetime of experience, an educated guess.

I had a question about how they dealt with it, and Juan Browne through research found the design details in the form of drawing and photos of the fixtures which gave me the information I needed to see the solution the engineers chose.




Back when I taught a class to apprentices entering the trade my first lecture was about what refrigeration and a refrigerant gas is.

My class would arrive with a hot plate setting on a table with a pressure cooker on top of it already at a boil. The lid of the cooker had a thermistor attached to a meter setting to the side, and a pressure weight which allowed me to control the pressure to 5,10, and 15 psi.

First I would demonstrate and record the temperature of the boil at the room pressure, then I would put the lid on and set the weight at 5, then 10 and 15 psi, and for each pressure I would record the temperature.

Then I would startle them by stating that what we were seeing there was evaporative refrigeration under the conditions of a 0, 5, 10, and 15 psi evaporator pressure.

Then I would create a pressure temperature chart for the refrigerant gas H2O on the chalkboard using that lab data.



Then to wake them up I would announce that the first refrigeration device made by mankind was made in a cave at the dawn of time by a cave women who stitched a watertight leather bag and hung it from sticks next to a fire. She filled it with water and chopped goat, and then she put rocks into it which had been heated red hot in that fire with tongs made from sticks. Once she'd established a boil, she had successfully invented the very first refrigeration device, and with it she had cooked the very first goat stew.

Then to convince them what I had said was true I would say water is not the only refrigeration gas available. If you don't want to refrigerate water to a temperature of 212 degrees to cook food. Perhaps you want to freeze that food. Using one of the other refrigerant gasses is ideal.

Then I would lift a jug of R22 freon up and turn it upside down and valve some of that out into a thin aluminum cookie sheet on top of foam insulation. At first it would just boil away, but after a bit the cookie sheet would chilled to about minus 35 degrees. The hard boil would settle down and form a pool of liquid which looked just like the soda 7up. Then I would ask them to come to the table and splash their fingers in it a bit to grasp it.

That lesson is helpful because without it there would be refrigeration techs running around on jobs who wouldn't understand what a refrigerant gas is, what it looks like inside of the steel jugs and copper pipes, nor would they understand how it works.


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PostPosted: Mon Mar 13, 2017 10:59 am 
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Sam Lefthand wrote:
What I'm pointing out is since the lake water is held behind a dam of great height, to release it from the bottom of the dam without a load to absorb the vast pool of energy that water holds, that the thermal aspects of what usually could be ignored with more normal dynamic flow through water works without that elevation factor have to be taken into account.

I saw an energy imbalance, and until I saw how it is dealt with as in the case of the river valves pumping a vast amount of air into the system to deal with the waters expansion I saw a large cooling effect which the law of conservation of energy dictates.

What they have designed to resolve that problem is inducing a reheat after a cooling effect to negate that problem. That induced air flow of warm air carries away much of that cooling effect. Even so I see it as an incomplete solution with limitations, but under the constraints of not operating the valves until the lake is only half full I would imagine that the major problems of the system would be manageable.

I'm doing this without doing calculations on the basis of a lifetime of experience, an educated guess.

I had a question about how they dealt with it, and Juan Browne through research found the design details in the form of drawing and photos of the fixtures which gave me the information I needed to see the solution the engineers chose.

Back when I taught a class to apprentices entering the trade my first lecture was about what refrigeration and a refrigerant gas is.

My class would arrive with a hot plate setting on a table with a pressure cooker on top of it already at a boil. The lid of the cooker had a thermistor attached to a meter setting to the side, and a pressure weight which allowed me to control the pressure to 5,10, and 15 psi.

First I would demonstrate and record the temperature of the boil at the room pressure, then I would put the lid on and set the weight at 5, then 10 and 15 psi, and for each pressure I would record the temperature.

Then I would startle them by stating that what we were seeing there was evaporative refrigeration under the conditions of a 0, 5, 10, and 15 psi evaporator pressure.

Then I would create a pressure temperature chart for the refrigerant gas H2O on the chalkboard using that lab data.

Then to wake them up I would announce that the first refrigeration device made by mankind was made in a cave at the dawn of time by a cave women who stitched a watertight leather bag and hung it from sticks next to a fire. She filled it with water and chopped goat, and then she put rocks into it which had been heated red hot in that fire with tongs made from sticks. Once she'd established a boil, she had successfully invented the very first refrigeration device, and with it she had cooked the very first goat stew.

Then to convince them what I had said was true I would say water is not the only refrigeration gas available. If you don't want to refrigerate water to a temperature of 212 degrees to cook food. Perhaps you want to freeze that food. Using one of the other refrigerant gasses is ideal.

Then I would lift a jug of R22 freon up and turn it upside down and valve some of that out into a thin aluminum cookie sheet on top of foam insulation. At first it would just boil away, but after a bit the cookie sheet would chilled to about minus 35 degrees. The hard boil would settle down and form a pool of liquid which looked just like the soda 7up. Then I would ask them to come to the table and splash their fingers in it a bit to grasp it.

That lesson is helpful because without it there would be refrigeration techs running around on jobs who wouldn't understand what a refrigerant gas is, what it looks like inside of the steel jugs and copper pipes, nor would they understand how it works.


I understand. pV=nRT

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PostPosted: Mon Mar 13, 2017 1:55 pm 
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Refrigerants have phase transitions at more practical temperatures than water. The principle's the same. Some of the heating and cooling effects associated with the phase transition of water contribute to what we call weather. Hurricanes come to mind. That's why they fall apart over land.

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PostPosted: Mon Mar 13, 2017 3:18 pm 
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Refrigerants have phase transitions at more practical temperatures than water. The principle's the same. Some of the heating and cooling effects associated with the phase transition of water contribute to what we call weather. Hurricanes come to mind. That's why they fall apart over land.


Yes.

Bernie mentioned the ideal gas equation of state. That is for an ideal gas. Water and CO2 are not even close to being ideal gases. That PV=nRT can be plotted to create a 3D graph, as can the real equation of state for both water and CO2, and when they are plotted one can see the phase transition lines. Both water and CO2 have two phase transition lines, one from the state of liquid to vapor, the other from liquid to solid, and both of them expand in volume from the liquid state.

The issue with the river valves is not the usual phase transition from liquid to vapor one sees involving weather and that boiling pressure cooker I discussed with my class. With the river valve situation, the phase transition which concerns me is the expansion transition from liquid to solid, an unusual situation.

The water at the bottom of the lake is in a high pressure stable subcooled state. And due to the non-ideal nature of water if it is forced to expand by being suddenly released from the high pressure, if it is subcooled enough it would lie too close to that liquid to solid transition line and it might be swept over it during that forced expansion, that expansion would take place as a shock wave.

That would be bad, in essence it would be another form of cavitation, one in which the cavitation did not affect just the surface boundaries, it would affect the whole of the flow. It calmed me down a lot when I heard that air was being blended into the water to break the vacuum.

That blending, literal blending, means we're not looking at the pure water phase situation anymore, the water has become a blended refrigerant, one containing water, oxygen, nitrogen and a little bit of CO2. The nature of that blend will shift the nature of that water toward it behaving more like an ideal gas. Except for the CO2, it is more similar to water than it is to an ideal gas, fortunately CO2 only makes up a very small percentage of that blend.

And in breaking that vacuum it also shifts the end state to a less extreme pressure differential transition, which moderates the possibility of crossing that phase transition boundary.

I tried to make this explanation less techish, however this is a three dimensional subject with boundary states and shock wave decompression to consider.

:|


Did you ever read Cat's Cradle, the book with Ice 9? There actually is Ice 9, but it isn't at all like the ice described in that book. There are 17 states of ice, Ice 1 through 17. I am not worried about any of them with relation to the dam, except good old normal everyday Ice 1. I just brought that up to illustrate the true complexity of the natural transition qualities of water when used as a refrigerant.

Of all of the referents water and CO2 are the hardest to deal with from an engineering standpoint. In coming years CO2 will probably become the most used.


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PostPosted: Tue Mar 14, 2017 12:22 pm 
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Sam Lefthand wrote:

Yes.

Bernie mentioned the ideal gas equation of state. That is for an ideal gas. Water and CO2 are not even close to being ideal gases. That PV=nRT can be plotted to create a 3D graph, as can the real equation of state for both water and CO2, and when they are plotted one can see the phase transition lines. Both water and CO2 have two phase transition lines, one from the state of liquid to vapor, the other from liquid to solid, and both of them expand in volume from the liquid state.

The issue with the river valves is not the usual phase transition from liquid to vapor one sees involving weather and that boiling pressure cooker I discussed with my class. With the river valve situation, the phase transition which concerns me is the expansion transition from liquid to solid, an unusual situation.

The water at the bottom of the lake is in a high pressure stable subcooled state. And due to the non-ideal nature of water if it is forced to expand by being suddenly released from the high pressure, if it is subcooled enough it would lie too close to that liquid to solid transition line and it might be swept over it during that forced expansion, that expansion would take place as a shock wave.

That would be bad, in essence it would be another form of cavitation, one in which the cavitation did not affect just the surface boundaries, it would affect the whole of the flow. It calmed me down a lot when I heard that air was being blended into the water to break the vacuum.

That blending, literal blending, means we're not looking at the pure water phase situation anymore, the water has become a blended refrigerant, one containing water, oxygen, nitrogen and a little bit of CO2. The nature of that blend will shift the nature of that water toward it behaving more like an ideal gas. Except for the CO2, it is more similar to water than it is to an ideal gas, fortunately CO2 only makes up a very small percentage of that blend.

And in breaking that vacuum it also shifts the end state to a less extreme pressure differential transition, which moderates the possibility of crossing that phase transition boundary.

I tried to make this explanation less techish, however this is a three dimensional subject with boundary states and shock wave decompression to consider.

:|

Did you ever read Cat's Cradle, the book with Ice 9? There actually is Ice 9, but it isn't at all like the ice described in that book. There are 17 states of ice, Ice 1 through 17. I am not worried about any of them with relation to the dam, except good old normal everyday Ice 1. I just brought that up to illustrate the true complexity of the natural transition qualities of water when used as a refrigerant.

Of all of the referents water and CO2 are the hardest to deal with from an engineering standpoint. In coming years CO2 will probably become the most used.


Present temperatures being measured on the lake... 49°F - 51°F. http://www.westernbass.com/lake/oroville
Granted this may not represent the temperature of the water on the very bottom, but it is an indication.
Yes! The water in the chamber is allowed to mix with the air, the chambers are ventilated for that reason, otherwise they would collapse under the suction created by the weight of the entrapped falling water, like a soda straw collapsing under a hard suck on it.

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Present temperatures being measured on the lake... 49°F - 51°F. http://www.westernbass.com/lake/oroville
Granted this may not represent the temperature of the water on the very bottom, but it is an indication.
Yes! The water in the chamber is allowed to mix with the air, the chambers are ventilated for that reason, otherwise they would collapse under the suction created by the weight of the entrapped falling water, like a soda straw collapsing under a hard suck on it.

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On the lake implies the top of the lake. The following addresses the bottom temperature, and explains why I referred to that water as a being in a "high pressure stable subcooled state." In addition to that there is also an additional biological concern. That is the depleting of the available oxygen dissolved into the water drawn from the bottom of the lake, fish need that oxygen.

So there may be reason to induce air into the river valve stream which mutually satisfies more than just engineering concerns for that incoming water being so near a thermodynamic critical state.

The following explains that dissolved oxygen issue and addresses the bottom temperature.


https://en.wikipedia.org/wiki/Lake_stratification

Lake stratification is the separation of lakes into three layers:

Epilimnion: the top of the lake.

Metalimnion (or thermocline): the middle layer, which may change depth throughout the day.

Hypolimnion: the bottom layer.

"The thermal stratification of lakes refers to a change in the temperature at different depths in the lake, and is due to the change in water's density with temperature. Cold water is denser than warm water and the epilimnion generally consists of water that is not as dense as the water in the hypolimnion. However, the temperature of maximum density for freshwater is 4 °C."


https://en.wikipedia.org/wiki/Epilimnion

"The epilimnion or surface layer is the top-most layer in a thermally stratified lake, occurring above the deeper hypolimnion. It is warmer and typically has a higher pH and higher dissolved oxygen concentration than the hypolimnion."

"Being exposed at the surface, it typically becomes turbulently mixed as a result of surface wind-mixing. It is also free to exchange dissolved gases such as O2 and CO2 with the atmosphere."


https://en.wikipedia.org/wiki/Thermocline

"A thermocline (sometimes metalimnion in lakes) is a thin but distinct layer in a large body of fluid (e.g. water, such as an ocean or lake, or air, such as an atmosphere) in which temperature changes more rapidly with depth than it does in the layers above or below. In the ocean, the thermocline divides the upper mixed layer from the calm deep water below.

"Thermoclines can also be observed in lakes. In colder climates, this leads to a phenomenon called stratification. During the summer, warm water, which is less dense, will sit on top of colder, denser, deeper water with a thermocline separating them. The warm layer is called the epilimnion and the cold layer is called the hypolimnion. Because the warm water is exposed to the sun during the day, a stable system exists and very little mixing of warm water and cold water occurs, particularly in calm weather."

"One result of this stability is that as the summer wears on, there is less and less oxygen below the thermocline as the water below the thermocline never circulates to the surface and organisms in the water deplete the available oxygen."


https://en.wikipedia.org/wiki/Hypolimnion

"Typically the hypolimnion is the coldest layer of a lake in summer, and the warmest layer during winter. Being at depth, it is isolated from surface wind-mixing during summer, and usually receives insufficient irradiance (light) for photosynthesis to occur."

"In deep, temperate lakes, the bottom-most waters of the hypolimnion are typically close to 4 °C throughout the year." 4 °C = 39.2 °F


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PostPosted: Fri Mar 17, 2017 5:35 pm 
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The spillway is going back into use after being shut down for three weeks. Blancolirio put a new video up yesterday and he mention that they were going to do this:

www.youtube.com Video from : www.youtube.com



There are quite a number of hair on fire videos about the dam circulating at YouTube as well. The newest hysteria is about Asbestos in the rock under the spillway.

Yeah, the rocks and soils in much of California have Asbestos in them. I guess people who don't like that can move away. :|


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PostPosted: Sat Mar 18, 2017 3:46 am 
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www.youtube.com Video from : www.youtube.com


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PostPosted: Sat Mar 18, 2017 8:59 pm 
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"In deep, temperate lakes, the bottom-most waters of the hypolimnion are typically close to 4 °C throughout the year." 4 °C = 39.2 °F

Oy, one of the more subtle details in physical chemistry:

https://en.wikipedia.org/wiki/Clausius% ... n_relation



Also (bullshit trivia that will likely forever rattle around in my head), probably worth noting that the density of water tends to be at a minimum (i.e. its volume is at a maximum) at 4 °C.


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PostPosted: Sun Mar 19, 2017 1:03 pm 
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Yes the same holds for Like Tahoe. The deep part stabilizes around 4 degrees C, water's minimum density, and just sits there all year. Real good for preserving the dead bodies the inhabitants of the north end have dumped in the lake during various Mafia struggles.

They were saying they'd need to use the spillway again. Apparently, they just did. He also said the power station is shut down again.

Maybe they'll find gold.

Love the drone in the shot at the beginning of the video.

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PostPosted: Mon Mar 20, 2017 7:43 am 
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Probably not cavitation.

I think a pipe under the slab or in or under the side wall which feeds the side wall water dribblers probably rusted out and created a sinkhole in the fill which undermined the support of one of the sections of the slab, it tipped up or down and then the damage grew.

Notice on the first photo, to the right of the red oval on the far side of the wall in the backfill earth there are two areas which appear to be washed out. The upper wash out appears to be at a higher elevation than that imperfection on the slab they are marking, and the lower washout is even with the mark. And it appears that below that point the water dribbler spaced along that wall is not flowing.

In the second photo they show a longer area of the channel, there is that big hole on the center, but the side walls appear intact, the water dribblers below the break have no flow.

In the third photo, before the breakup of the slab, when they were spilling only small amount showing the pocket of turbulence, that appears to me it may be a case of it sucking air and perhaps water up through a crack from beneath the slab, not cavation.

And in that same photo all of the water dribblers along both walls are not flowing at all. Like maybe they had them turned off because they had realized they had a water supply leak under there somewhere.

Clay tile does not rust. They maybe notorious for failing if not laid properly, but they don't rust.

They say it'll be upwards of a year before they can say what caused the failure. Even then they may not be able to say for sure as most of the evidence is somewhere down stream or in the spoil piles up top.

Given the problems they have had with cavitation on dam spillways in the past that's where my bet is. ;)

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PostPosted: Thu Apr 06, 2017 6:48 am 
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The Bee has been doing a bit of stinging lately.....

http://www.sacbee.com/opinion/op-ed/soa ... 29039.html
Repairs to the Oroville Dam main spillway were initially estimated to be in the $100 million to $200 million range. The Department of Water Resources has already spent that much just in emergency response. Independent experts are now saying that the main and emergency spillways will have to be entirely redesigned and rebuilt.

The costs have not been estimated but are likely to be at least in the $500 million to $1 billion range. In addition it is likely that the water levels in the reservoir will have to be reduced for safety and to allow the reconstruction. That will reduce deliveries to water users.



To fix it right they have to go back to damn near drought conditions?

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PostPosted: Thu Apr 06, 2017 7:27 am 
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To fix it right they have to go back to damn near drought conditions?

While they are at it, would be good if they also consider retrofits to the entire damn structure.


That whole process of squeezing gazillions of tons of cement-like materials into all the nooks and crannies, both above and below ground, seems like a good place to start.


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PostPosted: Thu Apr 06, 2017 7:59 am 
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While they are at it, would be good if they also consider retrofits to the entire damn structure.


That whole process of squeezing gazillions of tons of cement-like materials into all the nooks and crannies, both above and below ground, seems like a good place to start.


We learned of infrastructure upgrades the hard way with the 35W bridge collapse....

www.youtube.com Video from : www.youtube.com


Bridge reconstruction has gone crazy up here. Still not up to par, but they are doing a fairly good job as far as i can tell.

You'd think California has a bit more to lose by waiting for the disaster before rethinking dam upgrades.

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PostPosted: Thu Apr 06, 2017 2:09 pm 
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This is California. Like the rest of the country, this is how we fund infrastructure:

Raise taxes.

This is not how we fund infrastructure:

Cut somewhere else.

This is because the special interests all want their piece of the pie. In the case of infrastructure, WE are the special interest, and we have no effective organization like all the other ones do.

L.A. is currently voting on just that. They won't stop doing personal favors for real estate developers who make the problem worse, so up go the taxes again just to fix potholes. Bridges and all that? Too complicated. Ask again next year.

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