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A question for the Engineers
http://67.205.157.234/forums/viewtopic.php?f=5&t=4312		 Page 1 of 2
Author:  Navybrat85 [ June 8th, 2013, 1:17 pm ]
Post subject:  A question for the Engineers
So last night whilst swabbing the floors at ye olde gas station, I had what I thought was a novel idea...I'd design a "Green-Steam" ship for my AU. My idea? use solar panels to generate electricity, in turn used to heat boilers and make steam, and drive the turbines.
Obviously this would be different than a land-based solar-steam system (which uses the solar energy to heat the water directly, and then pipes it through a superheater before sending it through the turbines.)

Would it be possible, or practical, to fit a ship with solar collectors to generate electricity to make steam?
Author:  heuhen [ June 8th, 2013, 1:34 pm ]
Post subject:  Re: A question for the Engineers
it's possible, what you need is a special water that goes to steam at very low tempera tour (A type of water with a different density than normal water). But the big limit you going to have is size... Todays technology is not advance enough to get out so much energy you need for running a ship as you want.


But there have been solar powered ships that have been around the world...
Author:  acelanceloet [ June 8th, 2013, 1:36 pm ]
Post subject:  Re: A question for the Engineers
you change the energy from light to electricity to heated water. that means it is less favourable then the land based (light heats water to steam directly) almost per definition.
you might though be able with electrical heating to bring the steam under pressure, thus needing less heat from the light..... in which case it could become at least a lot more complicated, but it might be more favourable then the 'simple' system. somebody who actually understands thermodynamics (Timothy, mabye?) might say something more/better about that.

EDIT:(and what heuhen said made abselutely no sense to me..... huh?)
Author:  heuhen [ June 8th, 2013, 2:16 pm ]
Post subject:  Re: A question for the Engineers
acelanceloet wrote:
EDIT:(and what heuhen said made abselutely no sense to me..... huh?)

That's because you didn't have that type of education like I had once at the Engineering school, Where we had to study this type of heating system that we have up here in Norway, it work this way:


Take out "heat" out of sea-water by using that to heat up an different type of water that are at a different density than normal water thus it will start to steam at temperature already down to 4-9 grade Celsius, have that water to go into the turbines.

Since this water goes to steam at far lower temperature you can get more power out of the water, even at an cold winter-day!!

It's called for heat exchange. The same principles can be found in an air conditioning system. only made in a different way, and without water.


Note: some water-types or if you want to call it an condensed fluid, are transferring to steam when they are getting cooled down. But he want an different system.



This system is similar to that one we are using in a city here in Norway to heat it up by using seawater:¨

[ img ]

They look like this, and in AAlesund they are using three of them, just at a bigger scale, heating up houses during winter for around 40000 people:
[ img ]

This system can probably be also used in an solar system, the difference is that instead of seawater, you use the water from Solar panels to heat up the systems.



There are many ways to do it, many systems out there, I have just had about this systems at school since we was talking about trying to design a larger system that used an seawater-exchange to heat up the power-plant of a ship.
Author:  acelanceloet [ June 8th, 2013, 2:22 pm ]
Post subject:  Re: A question for the Engineers
still, what is low density water? pressurized? superheated? water has one density, or it is no water :S
Author:  TimothyC [ June 8th, 2013, 3:01 pm ]
Post subject:  Re: A question for the Engineers
Navybrat85 wrote:
So last night whilst swabbing the floors at ye olde gas station, I had what I thought was a novel idea...I'd design a "Green-Steam" ship for my AU. My idea? use solar panels to generate electricity, in turn used to heat boilers and make steam, and drive the turbines.
Obviously this would be different than a land-based solar-steam system (which uses the solar energy to heat the water directly, and then pipes it through a superheater before sending it through the turbines.)

Would it be possible, or practical, to fit a ship with solar collectors to generate electricity to make steam?
Ah! Thermodynamics/green energy is my specialty (just like Sith Lords are Obi Wan's). The problem you are going to run into is energy density. There just isn't enough inbound solar radiation do make the extra weight of the system pay off. I like the thought process, it just won't work in practice. You'll get better results with an electric drive and a Photovoltaic system.

Now, there is work being done with extracting waste heat from fuel cells to heat a working fluid and using that to drive a turbine and a generator. It shows some promise without much additional volume relative to a pure steam system. This is on top of the continuous work to extract more of the exergy from the exhaust gasses.
acelanceloet wrote:
still, what is low density water? pressurized? superheated? water has one density, or it is no water :S
I have pages and pages of steam tables that show that water can have a variety of densities under various pressures and temperatures. That said, I think he's actually talking about using Ammonia as a working fluid, which does happen in some situations. The downside is that it can explode when it comes into contact with water.

The diagram he gave is for a desalination plant, and the picture is of heat exchangers that are used to remove waste heat. The technology he describes makes me think of Ocean thermal energy conversion.
Author:  heuhen [ June 8th, 2013, 3:09 pm ]
Post subject:  Re: A question for the Engineers
[quote="TimothyC"][/quote]

Yeah my brain was in a drain :lol: I just remember things from engineering school... but I had forgot some small things like the name Ocean thermal energy conversion. :shock:

I used that drawing since I could find the correct one when I was looking for it, for If we remove the distillation part... then we almost have Ocean thermal energy conversion.


My idea was to instead for using seawater, I was to use the water that is in the system for the solar panels... The downside would be:

- Heavy water based solar panels.
- The Ammonia is perhaps not the best thing to use since it goes to steam to early... but then it can have the advantage of the ability to go to steam at lower temp.
- The size needed. The Ammonia plant part doesn't need to be big but the solar-panel...
Author:  odysseus1980 [ June 9th, 2013, 2:51 pm ]
Post subject:  Re: A question for the Engineers
If I designed such a vessel it would be a large trimaran to have large area for Solar Panels.Then do not forget that many conversions of energy form means losses.This powerplant you suggest would has very low efficiency,due to the PV.In theory,a good cost-effective PV has energy conversion (sunlight-to-electricity conversion efficiency) of only 17%-18%,which lowers significant overall powerplant efficiency.The best solution is to have as much solar panel area as possible,drive it to one Permanent Magnet Electric Motor (like those used in diesel-electric submarines,with 98% efficiency) and put your batteries in lower hull to use them as ballast.So the ship would have:Solar Panels-Transformers-Batteries and the load,electric motor connected to a prop.Batteries would be also used as ballast,positioned at keel.The vessel could be something like this:
http://forums.finalgear.com/off-topic/t ... 5/page-12/ or this http://www.nauticexpo.com/prod/konacat/ ... 69354.html but built in a much larger scale.Second is a convectional design,first looks exotic but the idea of a long,very narrow hull is more that 100 years old.

I have studied Energy Technology and know something about it.

P.S Look also this : http://www.newsbeast.gr/environment/art ... ko-skafos/
Not designed by me,but in my country.The article is in Hellenics,but can be translated easy online.Actually is a hybrid vessel,not pure solar powered.
Author:  Rodondo [ June 10th, 2013, 12:13 am ]
Post subject:  Re: A question for the Engineers
acelanceloet wrote:
water has one density, or it is no water :S
Heavy Water ;)
Author:  eswube [ June 10th, 2013, 8:41 am ]
Post subject:  Re: A question for the Engineers
acelanceloet wrote:
water has one density, or it is no water :S
Besides changes related to pressure and temperature, I believe there's also a difference in density between sea water (average 1025 kg/m³ on the surface), and fresh water (average 1000 kg/m³).
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