CR4 - The Engineer's Place for News and Discussion ®


Previous in Forum: keshefoundation.org Free Energy Plasma   Next in Forum: Vessel Design
Close
Close
Close
11 comments
Participant

Join Date: May 2014
Location: NC, USA
Posts: 2

Fluidyne Pumps

05/20/2014 2:36 PM

Hi everyone,

First time posting, discovered this site from the DasEnergy post with his "liquid piston engine" thread. Two pages of epic [something]. Good times... had to read the whole thing.

At any rate, I'm toying around with the idea of generating electricity using a conventional water turbine. The basic idea is to pump water to a higher elevation using a series of fluidyne pumps having the heat source being concentrated solar collectors (parabolic trough on equatorial mounts). Then run it through the turbine to another supply pond at lower elevation to complete the cycle and harvest the energy in a more controllable and constant manner.

My understanding is that fluidyne pumps are not very efficient, mostly because of poor harmonics. However, if one were to mitigate the harmonics to get the phase closer to the ideal cycle, is it even possible to get efficiencies comparable to current PV tech, say 0.15 to 0.20? I have read that some stirling engines have efficiencies over 0.30, but not with liquid pistons.

I'm attracted to fluidynes because of the lack of moving parts - two check valves is all you need. Up-front and maintenance costs are quite minimal. However, if the maximum "realistic" efficiency is less than 5%, it's not a very worthwhile endeavor, and the extra cost and complexity of a beta or gamma stirling is still worthwhile.

Finally, I should say that I am not an expert in thermodynamics, but I do have a basic understanding of physics and engineering concepts. (This should be obvious already). As such, I don't suggest that I'm going for perpetual motion or DasEnergy's 80% efficient ingnitionless combustion engine, or anything silly like that. I do, however, appreciate any links, advice, further reading hints, encouragement, and even discouragement that can be offered.

Thanks

Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
2
Guru

Join Date: Aug 2007
Location: Earth - I think.
Posts: 1950
Good Answers: 150
#1

Re: Fluidyne pumps

05/20/2014 3:01 PM

First off, welcome to the mad house!

According to this document 3-6% efficiency. I'd guess it is going to be difficult to push it up to that 6% mark.

__________________
TANSTAAFL (If you don't know what that means, Google it - yourself)
Register to Reply Good Answer (Score 2)
2
Guru

Join Date: Oct 2008
Posts: 39041
Good Answers: 1533
#2

Re: Fluidyne pumps

05/20/2014 4:38 PM

First, I'd ask myself how much power I needed, over what period of time each day. Easy enough.

Then take a look at the amount of water, at some elevation and flow, required to produce your energy needs, for a given period.

Then, I'd take a look at the energy required to pump that given quantity of water, to the required elevation, using the given source of energy available for the pumps.

You will soon see that the energy required to pump the water uphill, far outweighs the amount of energy you can produce with that water.

Oh, and don't forget to factor in those cloudy days.

Utilities use Pumped-storage hydroelectricity as a means of leveling out generating capacity. Not as a primary means of electricity generation.

Let us know how it works out for you.

Welcome.

Register to Reply Good Answer (Score 2)
Guru

Join Date: Apr 2011
Posts: 6029
Good Answers: 215
#3

Re: Fluidyne Pumps

05/20/2014 6:21 PM

A good question to ask when reviewing a description of efficiency is 'what input is the basis'?

The follow up question is how available/what is the cost of the input.

.

Since you are contemplating something that involves some land use for pumped storage, it is unlikely that the sun exposed square footage is likely to be your limiting factor. As such, efficiencies that you related in rough percentages are bound to be misleading.

.

Unless the total usable sun exposed area has already been accounted for in various uses, the efficiency per KW from sunlight is only of indirect consequence.

.

The efficiencies that you allude to when you mention things like few moving parts and low maintenance along with efficiencies related to capital costs and expected life are probably going to be far more helpful.

.

Estimates of lifetime useful output per lifetime cost is a better consideration of efficiency.

__________________
Eternal vigilance is the price of knowledge. - George Santayana
Register to Reply
Guru

Join Date: Apr 2014
Posts: 1876
Good Answers: 67
#4

Re: Fluidyne Pumps

05/20/2014 6:54 PM

As fluidyne pumps are so inefficient you may wish to consider a more efficient alternative: a solar brine pond in conjunction with an organic Rankine cycle (ORC) engine. The pond acts as both the solar collector and the energy storage medium to tide you over on cloudy days. The energy obtained is in the form of low-grade heat of 70 to 80 °C compared to an assumed 20 °C ambient temperature. According to the second law of thermodynamics (see Carnot-cycle), the maximum theoretical efficiency of a cycle that uses heat from a high-temperature reservoir at 80 °C and assuming an ambient air temperature of 20 °C is 1−(273+20)/(273+80)=17%.

With the proper choice of working fluids an ORC can be also used with your parabolic-trough collectors directly.

Welcome to CR4, btw.

You Don't Have To Be Crazy To Be Here - We Train You! ™

Register to Reply Score 1 for Good Answer
Guru

Join Date: Aug 2012
Posts: 927
Good Answers: 80
#5
In reply to #4

Re: Fluidyne Pumps

05/20/2014 10:32 PM

I actually gave you a GA just for the slogan!!

Register to Reply Off Topic (Score 4)
Guru
Technical Fields - Technical Writing - New Member Engineering Fields - Piping Design Engineering - New Member

Join Date: May 2009
Location: Richland, WA, USA
Posts: 19642
Good Answers: 737
#6
In reply to #5

Re: Fluidyne Pumps

05/21/2014 1:32 AM

Yeah, but watch out for the intellectual property lawsuit from Lyn-Door Industries!

__________________
In vino veritas; in cervisia carmen; in aqua E. coli.
Register to Reply Off Topic (Score 6)
Participant

Join Date: May 2014
Location: NC, USA
Posts: 2
#7

Re: Fluidyne Pumps

05/21/2014 9:32 AM

It's quite clear that I've come to the right forum. I remember reading about brine ponds a long time ago but had forgotten about that. I didn't realize that the water would get as hot as 80C. Even with my limited amount of research so far, I'm betting 0.17 efficiency is simply unattainable with a fluidyne pump.

My next question was going to be concerning liquids with a lower boiling point than water. I do know that the volume expansion when the phase change from liquid to gas happens is pretty extreme. Will study up more on the Rankine cycle.

Thanks for the nudges in the right direction. Thanks also for your collective patience with a curious layman.

Register to Reply Score 1 for Good Answer
Guru
Safety - Hazmat - New Member Engineering Fields - Retired Engineers / Mentors - New Member Engineering Fields - Piping Design Engineering - New Member Hobbies - DIY Welding - New Member Fans of Old Computers - PDP 11 - New Member

Join Date: Feb 2007
Location: Stronger Than The Storm
Posts: 2366
Good Answers: 201
#8

Re: Fluidyne Pumps

05/22/2014 10:48 PM

The inefficiencies of your proposed system will make it so ineffective you will be wasting a lot of electricity in trying to get a small amount. For each step that you change from one energy generating step you are losing energy to the equipment to run it. By pumping the water from a lower elevation to a higher one requires the theoretical pump power needs and also the inefficiency power losses of the pump. (Elevated stored water is intended only to shave or store for peak power usage generation). The turbine also has inefficiency losses. The piping has friction losses. You are going to have an extremely inefficient system.

Why not just take the initial solar cells, which are part of the system, and use that electricity? The subsequent losses after that step would be eliminated. There is no or very little loss in using that as the source. Everything else robs the system when final available power considered. A quick estimate is that the efficiency of the system as you have described it will be less than 5% or more likely less than that.

Good Luck, Old Salt

__________________
Any day on the green side of the grass is a GREAT DAY!, --- me +++++++++. I believe creativity is an inherent part of everyone. --- Kermit T. Frog
Register to Reply
Guru

Join Date: Apr 2011
Posts: 6029
Good Answers: 215
#9
In reply to #8

Re: Fluidyne Pumps

05/23/2014 12:06 AM

Old Salt,

I missed the parts about solar cell or other inputs of electricity.... where is that?

__________________
Eternal vigilance is the price of knowledge. - George Santayana
Register to Reply
2
Guru
Safety - Hazmat - New Member Engineering Fields - Retired Engineers / Mentors - New Member Engineering Fields - Piping Design Engineering - New Member Hobbies - DIY Welding - New Member Fans of Old Computers - PDP 11 - New Member

Join Date: Feb 2007
Location: Stronger Than The Storm
Posts: 2366
Good Answers: 201
#10
In reply to #9

Re: Fluidyne Pumps

05/23/2014 8:10 AM

truth is not a compromise-

Yes, you are correct. Don't know why I went on that train of thought but I now recant it.

Now that I have read it correctly I restate my conclusion, the efficiency will be even less than I projected. Circulating water solar panels are even less efficient than PV cells. Also, efficiency aside, the parabolic reflector doesn't provide any more BTU's than a flat panel since it is dependent upon the area of the solar(s) panel exposed to the sun, just as a flat panel water collector is. The parabolic does increase the temperature of the water but at the expense of the volume of heated water available. Also the parabolic reflector would have to be connected to a tracking system. If not, the parabola would only generate heat for a very short period of time when the sun was directly in front of it.

Confirmation of this is the sale of General Electric's water based solar collection cells, at a great financial loss, 24 years ago to a small entrepreneur based in Orange, NJ. GE marketing saw that there was no future in the water collectors vs. PV collectors so they shut the operation and sales down. The entrepreneur set up the whole operation, including a vacuum deposition chamber, and never made or sold a water solar panel. Finally it was sold to China at a great loss.

Powering the pumps directly from PV cells would increase the efficiency of the system. Also storage of electricity is much easier and cheaper than attempting to store heat. Since the original source of energy is the sun, why waste it on equipment efficiency losses?

A GA for you Sir!

Good Luck, Old Salt

__________________
Any day on the green side of the grass is a GREAT DAY!, --- me +++++++++. I believe creativity is an inherent part of everyone. --- Kermit T. Frog
Register to Reply Good Answer (Score 2)
Guru

Join Date: Apr 2011
Posts: 6029
Good Answers: 215
#11
In reply to #10

Re: Fluidyne Pumps

05/24/2014 4:18 AM

Thanks Old Salt, I think your answer is a good one as well.

I agree with your analysis. If electricity without burning fuel is the end goal, it will be hard to compete with mass produced solar cells and/or wind turbines on a lifetime KW-hr/$ basis.

.

I think there might be some niche uses that a fluidyne pump might serve well though. One of those niche uses would be reliable, low maintenance, minimal initial and total cost, water pumping.

.

Also, while a focused optics paraboloid dish would need a tracking system continually making adjustments, there are options for non-focusing optic semi-parabolic troughs aligned east-west that might require slight seasonal adjustments or possibly none at all. Since fluidyne pumps work well with a concentrated heat source, it would make sense to have a number of these along the trough in series-parallel arrangement as needed.

.

It wouldn't provide any advantage for generating electricity, but there is potential for a robust inexpensive system that could pump for years with very little upkeep.

__________________
Eternal vigilance is the price of knowledge. - George Santayana
Register to Reply
Register to Reply 11 comments
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Comments rated to be Good Answers:

These comments received enough positive ratings to make them "good answers".

Comments rated to be "almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, rate them!
Copy to Clipboard

Users who posted comments:

europium mkII (1); JNB (1); Kilowatt0 (1); lyn (1); old salt (2); Platypus (1); Tornado (1); truth is not a compromise (3)

Previous in Forum: keshefoundation.org Free Energy Plasma   Next in Forum: Vessel Design

Advertisement