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Re: Implenting Case Lacoon I & II after Oyster Bay | |
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by namelessfly » Fri Oct 29, 2010 9:56 pm | |
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Perhaps the Solarian League is importing a lot of food because they're deterraforming their planets to restore the pristine, non terrestrial ecology. As a result, it is no longer possible for them to grow significant quantities of food so they have to buy it or steal it from Shell worlds.
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Re: Implenting Case Lacoon I & II after Oyster Bay | |
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by Thirdbase » Sat Oct 30, 2010 12:24 am | |
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They have to restore the land so the Spotted Owls can eat the Snail Darters. ------------
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Re: Implenting Case Lacoon I & II after Oyster Bay | |
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by namelessfly » Sat Oct 30, 2010 3:12 am | |
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I'm obviously having a lot of fun here but I suspect that the ecology of terraformed worlds would tend to be fragile. Planets would tend to revert back to their natural state without the continuous expenditure of effort to keep them terraformed. I'd also expect that rather than making almost the entire planet habitable as Earth is, terraforming would make a norrow band of lattitude either at the equator or at the poles habitable. It would work well when there are only a few million colonists for the planet to support. It would still function when that population has grown to a few billion people. However; once populations grow to a few tens of billions of people they'd start have difficulties. Given the population surges that would result if the introduction of prolong didn't coincide with a reduction in birth rates, many of the SL core worlds would find it far more cost effective to import rather than grow much of their food.
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Re: Implenting Case Lacoon I & II after Oyster Bay | |
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by bafoote » Sat Oct 30, 2010 1:21 pm | |
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No kidding that would be impractical. He was trying to drop the bottom threshold for TC on said turbine a whopping 20C at best??? Simple power consumption and heat transfer calc would tell him it was a waste of time and money filing for a patent as efficiency of freezing is about 60% to 80% IIRC maybe 82% on VERY large scale stuff like what your bro was trying to do. Off peak power isn't that cheap! Add in start up costs, ROI, and storage wastage energy to surrounding environment. Break even at best. Actually, its what modern office buildings do today to save cooling costs. At night time they create huge stockpiles of ice to be used later in the day for cooling the building down. The difference here is that the differential between TH and surround TC is very small so shrinking the TC by roughly 20C makes a GIGANTIC difference in their COP(Coefficient of Performance). This is where your brother loused up his implementation of his patent. Said turbine would already have a HIGH TH and creating a very slight difference in TC isn't going to help much. Most TC on turbines is lake water or river water that on MOST places not in the equator region is around 60F or lower or 12C. Add in efficiency of freezing ice and it drops to around 8C differential added. Add in the cost to make a special build turbine that can take advantage of said extra 8C LOW temperature, IE a VERY expensive low pressure turbine and the costs skyrocket. Remember I stated that for their high efficiency today, low pressure turbines have to be reheated so as to not create water droplets on said blades. If your bro's condenser helper was implemented, what it really means in a practical sense is that they have to flow less feed water(water pump efficiency --> very little to gain here) through the condenser and a slightly more efficient condenser. Not exactly much to gain here as the energy of said low pressure turbine or chamber whichever term you want to use, is taken out via pressure drop to near a vacuum already. Now if the fluid were changed from something OTHER than water, then yes, we could drop the TC to say Liquid Oxygen temperatures, but what fluid remains a liquid/gas at said temps? Well we would have to use Hydrogen or say Helium. Not exactly very dense "steam" nor do they carry a high quality of heat(heat transport)(enthalpy). Why Ammonia/R134 work as a turbine fluid. Even though their density is lower, IE requiring more expensive turbine blades, IE LARGER, their heat capacity isn't all that bad(enthalpy curves). No where near water of course, but then nothing is. Its why France never got their helium Nuclear Reactor to work. The thermal transport of Helium(enthalpy) is too low and they couldn't reliably cool the nuclear material, and thus the holy grail of nuclear fission reactors, died. |
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Re: Implenting Case Lacoon I & II after Oyster Bay | |
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by bafoote » Sat Oct 30, 2010 1:24 pm | |
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Back to Lacoon 1/2
The 12x time in shipping. Got THERE and BACK extended time in transit remember. So its really 6x to said destination and another 6x back. Of course DW could have really meant 24X as its the round trip number we care about due to the fact that folks out in the verge aren't omniscient and know what the Lords and Masters in the SL would wish to be shipped to appease their Oligarchy appetites. =) |
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Re: Implenting Case Lacoon I & II after Oyster Bay | |
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by namelessfly » Sat Oct 30, 2010 6:04 pm | |
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Concept was designed for Southern California market where coolant supply is often limited forcing recirculation through cooling towers so normal TC is higher than river water. Also predicated on presumption that you would use off peak hydropower to do the freezing so the differential in off peak power cost to peak power value would be much higher.
The concetp didn't go anywhere but it was worht doing since CHicago Bridge and Iron picked up the tab for getting the patent with understandings that they'd get advantages if the idea became marketable.
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Re: Implenting Case Lacoon I & II after Oyster Bay | |
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by bafoote » Sat Oct 30, 2010 7:16 pm | |
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Erm even if it was 40C, it wouldn't help much due to the nature of water as the working fluid. That was the point I was trying to make, obviously poorly. Why? When one gets close to the liquid line on your T/P H2O graph especially as the temperature gets closer and closer to its STP liquid point, the quality of said heat is worse and worse due to droplet formation, vapor pressure in simplified terms. Why one has to reheat the low pressure end of turbines. What this means is that trying to extract a super low efficiency by "improoving its already low efficiency area is a losing proposition.
Congruently it is also why an increase of 20C at the TOP end is such a bonus due to the nature of water. The low end and the top end for efficiency are nowhere close to the same. THe simplified standard equation for thermal efficiency really doesn't tell the story. At a blind glace it seems obvious that if you lower the low temperature sink further it would improve efficiency. It doesn't. It entirely depends on the fluid being used especially as you get near the transition from gas/liquid to liquid transition.
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Re: Implenting Case Lacoon I & II after Oyster Bay | |
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by namelessfly » Sun Oct 31, 2010 5:18 am | |
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Keep in mind that niether my brother nor his widow got rich off the royalties from his patent. I didn't say it was a great idea. CBI which incidentally had built only once bridge during its entire hundred plus year history had no special expertise in gas or steam turbines and niether did my brother. I just mentioned it to illustrate how small temperture differentials can make a difference.
Also, as I recall after hearing my brother describe the process over two decades ago, the antipated application was to provide a heat sink for the NG fired gas turbines that were in vogue back then rather than the far more sophisticated and awesomely effecient combined cycle plants that you and your collegues have developed over the years. Getting back to OTEC plants which is what started this discussion, most of the designs use an intermiary working fluid in a compact, higher pressure turbine as you suggest. The direct cycle is simple but cost inneffective unless producing fresh water is a critical role of the installation. A one GW plant would be producing about a million tons of fresh water per day.
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Re: Implenting Case Lacoon I & II after Oyster Bay | |
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by SWM » Mon Nov 01, 2010 11:45 am | |
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I suspect the x12 time in shipping comes from a simplistic comparison of a distance of 40 light-years from Beowulf to Old Earth, vs. 500 light-years. --------------------------------------------
Librarian: The Original Search Engine |
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Re: Implenting Case Lacoon I & II after Oyster Bay | |
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by thinkstoomuch » Tue Nov 09, 2010 10:15 am | |
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Another stupid thought that may have been addressed previously. If it has please point me to it, I would be appreciative. In response to the twelve times transit times for people that do not have access to the wormholes. Why not fit military grade Hyper Generators. It will not get you back all 12 times but will get you back 2 to 2.5 the time if using the Eta or Theta bands. Previously it was not economic sense but if you can make 2 to 2.5 times the number of trips that will change the money equation significantly. From the way that the merchant ships are constructed may be a simple change that does eat some cargo space between the larger generator and additional people to maintain it. Like I said stupid thought that came to me as I was rereading some past posts. T2M -----------------------
Q: “How can something be worth more than it costs? Isn’t everything ‘worth’ what it costs?” A: “No. That’s just the price. ... Christopher Anvil from Top Line in "War Games" |
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