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Research Help!!

Unread postby TomSaidak » Sun 01 Feb 2009, 22:15:18

In trying to find some stuff on the internet, I have run into two major roadblocks.

The first road block - I can find all sorts of suggestions for improving passenger car and light truck mpg, but I cannot find a durned thing for big rigs/5 wheelers. Is no one working on this, or is there some arcane google foo one needs to locate the information?

My second road block...
I am attempting to see what would actually be involved in using US deserts to plants concentrated solar plants - the ones with the liquid sodium heat storage tanks.

My question is how to determine water flow in a flat, sea level canal, and whether pumping out water at the end farthest from the sea would increase the flow rate, and if so is there a natural speed limit. For instance, if a canal had a cross section of 10 square meters, went 100 miles, with no grade change, what would the water flow be if...
I pumped the water out at 100 cubic meters a minute? 200 Cubic meters per minute. How fast could I pump out the water without the pump sucking air?

Thanks in advance. I just can't seem to frame the question/search terms to get anywhere useful. After about 7 days of trying, I am getting frustrated...
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Re: Research Help!!

Unread postby lper100km » Sun 01 Feb 2009, 23:14:11

Not sure what you’re trying to do with a 10m sq canal in the desert.

A canal anywhere, which by definition is level, will have no natural flow. That’s what they are for – to provide an artificial lake to facilitate boat transport. The largest examples of these are the Suez and the Panama. You can pump out as much as you like and providing the flow is returned or replaced, there will be no change in level and volume. The desert location is problematic, since loss by evaporation will be significant and will place a severe strain on your ability to replenish. You could easily end up with a man made gulch. Canals in the desert are generally considered to be not a good thing.
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Re: Research Help!!

Unread postby TomSaidak » Mon 02 Feb 2009, 03:21:14

Pstarr wrote:

$this->bbcode_second_pass_quote('', 'N')ot sure what you’re trying to do with a 10m sq canal in the desert.


I am using 10m cross section to keep the math simple.

I am trying to determine either how it would be possible, or IF it would be possible to use large scale concentrated solar power in US deserts, as they mostly tend to be, well, rather dry. CSP requires 670 gallons per MWH. It loses about 5% or about 35 gallons to evaporation during cooling the steam back to water. So a 6000 MW plant is going to need about 201,000 gallons of water an hour during peak operation. Thats alot of water to get in a desert.

Back to my problem.....
Ignoring tides, that flat, sea level canal has zero flow to it. But it has a potential flow, if it is drained at one end. What is that potential flow? If I pump water too fast, the pump will start sucking air. So I am trying to figure out how fast the water would flow to fill in the "void" created by sucking out water at the far end. If I pump out 100 cubic meters of water a second, will the canal refill before my pump starts sucking air? It if refills, what is the fastest it will refill before the pump starts sucking air?

Water in desert, bad idea... Well that depends on the water. This being salt water, I would think it is probably pretty bad. Thats another reason for finding the fastest the water will flow to refill the canal. Once I have that number, then I can determine whether or not the canal can be covered to either minimize, or sealed to prevent evaporation. That after a whole host of other problems get resolved.
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Re: Research Help!!

Unread postby lper100km » Mon 02 Feb 2009, 13:51:52

Google is your friend. Read this, or something like it, before you post again on this topic, please.

Basic Hydraulics Text Book
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Re: Research Help!!

Unread postby AAA » Mon 02 Feb 2009, 17:19:53

$this->bbcode_second_pass_quote('TomSaidak', 'I')n trying to find some stuff on the internet, I have run into two major roadblocks.

The first road block - I can find all sorts of suggestions for improving passenger car and light truck mpg, but I cannot find a durned thing for big rigs/5 wheelers. Is no one working on this, or is there some arcane google foo one needs to locate the information?


Here are some interesting articles about trucks in the LA Harbor.

CNG Trucks

Daimler Delivers 232 Natural Gas Trucks to Ports of Los Angeles, Long Beach

Freightliner delivers 132 LNG trucks to Port of Long Beach

.
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Re: Research Help!!

Unread postby Ludi » Mon 02 Feb 2009, 18:06:25

$this->bbcode_second_pass_quote('TomSaidak', '
')Water in desert, bad idea... Well that depends on the water. This being salt water, I would think it is probably pretty bad. Thats another reason for finding the fastest the water will flow to refill the canal. Once I have that number, then I can determine whether or not the canal can be covered to either minimize, or sealed to prevent evaporation. That after a whole host of other problems get resolved.


Pretty energy intensive to move those volumes of water. What energy source will you be using to move the water?

Look into the California Aqueduct to see the kinds of engineering challenges involved in moving large volumes of water long distances.

To be honest, I don't know why you're wasting your time puzzling about such a huge project. What is your goal? Just curious.
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Re: Research Help!!

Unread postby peterkarl » Mon 02 Feb 2009, 19:32:48

[quote="TomSaidak"]My question is how to determine water flow in a flat, sea level canal, and whether pumping out water at the end farthest from the sea would increase the flow rate, and if so is there a natural speed limit. For instance, if a canal had a cross section of 10 square meters, went 100 miles, with no grade change, what would the water flow be if...
I pumped the water out at 100 cubic meters a minute? 200 Cubic meters per minute. How fast could I pump out the water without the pump sucking air?
quote]

Tom,

first you ought to decide whether you need 100 cubic meters a minute, or rather 200,000 gallons per hour. That's a huge difference. That's either 16.7 m3/s or only 0.21 m3/s.
In the first case, a canal may be a reasonable thing. If it's 100 miles long, it's got to be inclined or the water won't flow. There's no use in sucking to get the water going 100 miles, you need a small slope.
In the second case, you don't need a canal, but a pipe, because thats not a lot of water. Again, sucking is useless, you have to have a pump where the water comes from, and many more pumps at intervals in the pipeline.
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Re: Research Help!!

Unread postby yesplease » Tue 03 Feb 2009, 03:17:41

$this->bbcode_second_pass_quote('TomSaidak', 'T')he first road block - I can find all sorts of suggestions for improving passenger car and light truck mpg, but I cannot find a durned thing for big rigs/5 wheelers. Is no one working on this, or is there some arcane google foo one needs to locate the information?
Read this, and some stuff from here for info on trucks.

In terms of CSP, using salt water may not be too bad of an idea as long as it's separate before it gets "distilled" into fresh water when used to cool the plants. Not that the drop in efficiency going from water to air cooled CSP is a killer. That said, I've no clue about your question.
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Re: Research Help!!

Unread postby yesplease » Tue 03 Feb 2009, 03:18:11

$this->bbcode_second_pass_quote('pstarr', 'T')omSaidak a very nice, sincere wack job.
Says the great biofool! ;)
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Re: Research Help!!

Unread postby TomSaidak » Tue 03 Feb 2009, 22:25:40

As regards to trucks, thank you AAA and yesplease. I also visited the Peterbuilt website and was surprised to see hybrid big rigs being sold or advertised and theoretically available soon. Thanks to your all’s help, I now know what to google and I have websites to watch.
lper100km wrote:
$this->bbcode_second_pass_quote('', 'G')oogle is your friend. Read this, or something like it, before you post again on this topic, please.

Thanks for the book link, I may or may not get there if no one else can help. Other then that, I will stand on my 1st Amendment rights.
As to CSP, to be clear I am talking about Concentrated Solar Power, not concentrated photovoltaic power. This is the type of solar power where you heat sodium to the point that it melts.
yesplease wrote:
$this->bbcode_second_pass_quote('', 'S')ays the great biofool!

Once pstarr gets over his math phobia, he will be able to participate in adult discussions. It’s his lack of math that sets him up for some of what he thinks and says.
Ludi Wrote:
$this->bbcode_second_pass_quote('', 'L')ook into the California Aqueduct to see the kinds of engineering challenges involved in moving large volumes of water long distances.

I did, and if I go by that, I am sunk before I start. It depends on a lot of pumping, and my initial canal sizes show that pumping may be something to avoid like the plague.
$this->bbcode_second_pass_quote('', 'T')o be honest, I don't know why you're wasting your time puzzling about such a huge project. What is your goal? Just curious.

Wasting time?? What else do I have to waste? As to what I am doing, I am evaluating CSP proponents statements that they can solve the US electrical generation problem with just a 92 mile by 92 mile section of desert. One way around the Peak Oil problem is to make it go away by switching to NG. Hard to do if we are using it for primary electrical generation. I am trying to develop numbers and a pathway to funding to see what alternative electrical generation strategies might work. Due to the waste problem, I tend to be allergic to nuclear. Though, there has been an interesting development that changes the equation - a fusion/fission plant that ends up with no waste to take care of.

Meanwhile.... If we were to go seriously CSP, we would need 424,490,229 m[sup]3 [/sup]of water an hour, 24/7, 365 days a year. This is based on the fact that you need 670 gallons of water per MWH, and you can only recover 95% of that by recondensing the steam back to water. That's a lot of water. The only source I can see for that is sea water. The problem with CSP is that the best locations for it are in deserts. Lots of sun. Water thin on the ground......

So, if we use CSP, we have to feed it water. But we want to locate it where there isn't much water. So it has to be brought in. To avoid issues of weather, I had pictured this centered around 6 nodes; East Oregon, south of Las Vegas, Death Valley, south of Phoenix, south of Santa Fe, and southeast of El Paso, Texas. Each node will need 7,074,7371m[sup]3[/sup] of water an hour, 24/7.... This would call for a pipe with a diameter 158.15 meters. The largest pipe I can find is 252" or 6.37 meters. At 6.37 meter diameter, to achieve the needed water flow would require 618 pipes. If stacked 4 pipes high, it would require a minimum swath of 983 meters wide. This assumes a minimum flow rate of 1m/sec, or 3.6 km/hour.
So, back to my 10 m[sup]2[/sup] cross section canal. A canal connected to the ocean, at sea level will have a water flow. It is commonly referred to as tidal flow. So yes, Virginia, there is a flow rate. It is rather complicated, and ultimately not helpful. The CSP plant will need to be able to get water during low tide.
So back to my theoretical 10m[sup]2[/sup] cross section canal. The CSP plant at 6000 MW generation, will need to suck up alot of water. Keeping to a mathematically simple canal with a 10m[sup]2 [/sup]cross section...
The plant sucks up 100m[sup]3[/sup] of water. According to petercarl, my canal ends of with a 10m[sup]3[/sup] section, that never gets water again. I don't believe that will happen - nature abhors a vacuum. That 10m[sup]3 [/sup]section WILL refill with water. My question is how fast. For example, if it refills at 3.6 kmph, then we will need a 158 meter diameter pipe. If it can refill at 36 kmph, then we will need a 50 meter diameter pipe. If it could refill at 360 kmph, then we would need a 16 meter diameter pipe. This would be feasible and economical. A 158 meter diameter pipe isn’t. A 50 meter diameter pipe MIGHT be. But before I can figure a pipe or canal size, I need to know big. A 16 meter diameter pipe is definately feasible, but I don't think we will get a 360 kmph flow.

Sloping of the canal may or may not be possible. I have not done the topographical mapping yet, as first I need to know how big a pipe or canal I need to have. There is an interplay between sidewall friction and depth of canal that enters into this. The problem with any CSP plant is that it has to be far inland enough that it doesn’t get whacked by hurricanes, is not in tornado alley, and is not next to a large fault zone. As I recall, Brownsville has been whacked by hurricanes. I have been on the highway from Dallas heading back to San Francisco, and heard a tornado alert on FM radio while still in Texas. Hence the need for a canal.
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Re: Research Help!!

Unread postby TomSaidak » Wed 04 Feb 2009, 02:59:06

Well, I'll be dipped in, something........

While waiting for help on the canal, I googled information on the Salton Sea in California.

Salton Sea

Under "Potential Solutions" it describes a pipe and pump system for 1,100,000 acre feet a year using a 16ft diameter pipe. It would take 7 of them to supply enough replacement water to run 73 EU style 6000 MW facilities. Flow rate to deliver 1.1million acre feet a year is 8.4 kph in a pipe with a 16' diameter. Case closed for now.

Thanks folks!!
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Re: Research Help!!

Unread postby Ludi » Wed 04 Feb 2009, 11:43:43

Thanks, Tom. I guess I'm used to people researching things they are interested in pursuing themselves, that is, things they are investing in or building. I get the impression you aren't actually investing in or planning to build a project of this kind. So I'll leave you to your academic research. Have fun! :)
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