Distilling Water via Human Power

We did some more searching and talked to our professors. So far the only generator we could find is this one:

http://www.windstreampower.com/generators/443541.html

I found others but they were either to weak (4W-20W) or more then we needed (1000WW+). Can anyone help locate some crank generators around 100W or so.

You all forget that the human body is a heater and if you take a container that rests against the skin with a large area it will heat the water to 30-35C and if there is a vapor path the a condenser at ambient you will get transference of water from warm to cold via distillation. It would also be a good idea to remove as much air from the system as you can bia a hand operated pump.

If you want to purify water by human methods, use membrane osmosis and the person pumps the water up to 100 PSI on the membrane and collects pure water on the other side. Not distilled, as it has not gone from fluid to vapor to fluid.

The rules of the contest state all energy input needs to come from human input (eg non-solar or anything of that nature). We have to distill the water so the membrane osmosis would be against the rules. We are aware boiling is the least efficent way to purify water. The hand pump idea was suggested to us by a professor at our college. Do you know of any hand pumps that would fit our need and where we could purchase them? We are not in the industry (so to speak) so finding vendors for parts is becoming a bigger task then we initially imagined. On a side note we came across many sites that sell permanent magnet motors. We read that if we just provide the rotation the motor will act as a generator. Can anyone verify this claim? Also will it be efficent as compared to a unit that was design to be a generator? Thanks you for the reply.

Why go from mechanical energy to electrical energy to a heater into heat.

Why not use something like a stationary bicycle and replace the drive wheel with a small container where the bicyles energy is disspiated as frictional heat. Two plates rubbing against each other with a way to change the pressure between them is what you need. This would need insulation so the only way for heat to leave is via steam into the condenser.

A human on a bike can put out 200 watts on a continuing basis and a lot more for short periods. So 100 watts is probablt doable for a hour or so.

Why not just use your bicycle sprocket chain drive to run a mechanical compressor and compress CO2, use the hot CO2 to heat the water to boiling, then expand the CO2 to cool the distillate?

We don't have much time left to complete the project so I doubt we can pursue this route. If only we had posted here sooner maybe we could have followed this unique idea further. This would surely have set us apart from the rest of the teams.

Get an old automobile alternator or a medium size permanent magnet DC motor. You will need to use some pulleys to get the rpms up on the shaft of the device and it isn't the most efficient way to go but hey you could get an alternator at a scrap yard for not much. The alternator has to have power supplied to it's field coil but there might be enough residual magnetism to "bootstrap" itself into operation without a battery if you connect the field to the output. The permanent magnet motor won't need any power to start. It is not designed to be efficient as a generator but it will work and if all you need is 48 watts and a human can crank out 200 this should not be an issue.

"Get an old automobile alternator..."

In really old cars (I drive a 1965 International Scout) alternators were not used. You can actually find a true generator in vehicles made in the early 1960's. Try doing some internet searching and then go down to your local junk yard or "Pick-a-Part" type yard. I believe these will be small, so you will need more than one.

Also, using pressure to change the boiling point is not a bad idea. A vacuum pump of some sort? That might be against the rules, but if you do some internet searching on vacuum distillation you should find good ideas. I remember as a student we had a multiple column system where the heat in the first unit vaporized the liquid in all three units just by varying the pressure (vacuum) in the 2nd and 3rd unit. It has been a while since I work in this area, but I am sure there are examples out there on the net.

Why did you say that distillation by heating the water is the least effecient .... in what sense it is the least effecient. I am engineering student like you and for FYP i am designing a portable water purification system .

If you desire to heat using electricity generated by human power, I would suggest you get an old bicycle lighting generator. Although the permanent magnet motor will work the generator is more efficient. I'm not familiar with the rules of your contest, but ASCE has a similar contest that requires roughly drinkable water. If this is required, reverse osmosis membrane with human powered pump is the best. The pressure necessary and with time constraints considered, you will need a lot of pressure. Try looking into a double piston pump.

Yes more efficient but with the watt or two you will get from it you may not be able to overcome the thermal losses to bring the water temperature much above warm. Maybe if you boil a tiny drop at a time it could work.

Reducing the air pressure above the water in some manner (steam extraction) is not a stupid idea either as the lower the air pressure, the lower the boiling point...less energy required to boil the water...a very small vacuum pump powered off the (Bike?) generator should help here....as long as the water is above about 73°C, (please check this statement out fully) I think most bacterial organisms are killed.....unless of course bacteria are not a problem in this case, then go for an even lower pressure/temperature. I hope this helps in some way.

Some time ago I saw a device that could boil water directly from mechanical energy. The device consisted of a cylindrical chamber with a cylindrical impeller inside it. Evidently by varying the separation between the impeller and chamber and by adding small dimples to both impeller and container you can use it to boil water. There was a dubious claim that the device was more than 100% efficient but in any case it would be more efficient than trying to generate electrical energy and then using that to boil water.

I can't remember what this device was called nor the details on its construction but somebody out there may be able to give you a clue where to look on the net.

In the R&D Division of BHEL, a $ 3 Billion Power Plant equipmentManufacturing company, there is a seperate design centre dealing withPermenant Magnet Generator. You could get in touch with that team.Normally, they do these on commercial basis. Since you are fromCollege, they may be willing to help at cost.

You have tocontact mr. SK Goyal, Group General Manager in charge of BHEL R&DDivision. Dr. UKChoudhary is theexpert concerned with Permanent Magnetic Generators.

I do nothave their emails handy. You can get the email of SKGoyal or Dr. UKChoudhary from N.Sundarrajan at nsrajan@bhelrnd.co.in. Sundarrajan'sgroup can help you forheating element design.

Best wishes,

jagannathanp@gmail.com
Dr.P.Jagannathan
Executive Director (Retd), BHEL

Thank you all for your input and replies. I'm currently busy with other school work so my time to post on the forums is limited. However this weekend I should have some free time to look over your suggestions in more detail.

On a side note incase anyone is interested in the ASME design contest, more information can be found here.

http://www.asme.org/Events/Contests/DesignContest/2007_Design_Problem.cfm

I've been in contact with watlow company and am in the process of finding a heating element for our project. The generator still alludes us, most likely we will being buying the one in second post. However if anyone knows of any vendors selling generators please let us know.

Again thank you all for your input and replies.

Don't forget to check eBay!

Instead of generator and heating element in seperate chamber, combine it all into 1. Submerge a permanent magnet generator in your water and short the output. When you crank it you will get heating from friction, induction, hysteresis, resistance. A cheap low efficiency iron laminate motor would actually be better than more expensive units. The same things that would cause them to burn up input power as waste heat to the atmosphere would put those watts into your water.

slo

Interesting idea, I'll have to discuss this with my group and some EE professors. We however have found a cheap ($50) generator. We hope to hear back from the manufactor soon as to if this would meet our needs. Incase you're wondering what we're looking at or could provide some input. http://www.mcmillanelectric.com/

Although I understand your thinking, what you may not realize is that the designer of the generator has balanced the design to produce maximum efficiency at a certain voltage and current output. Shorting the device will create an operating condition that it was not designed to accommodate. In all likelihood, it would be best to use a resistance element that would utilize the output at its most efficient design point. If you want to wrap it with some copper pipe or some other means to pre-heat the water and cool the generator that may be useful however you may find that when operated properly the generator does not produce a great deal of waste heat.

Here is a thought. May be just crazy enough to work:

Using a human powered DC generator to produce hydrogen and oxygen from the water by electrolysis. Collect the two gases bubbling off the electrodes and feed them (separately) through a catalytic converter (avoiding the danger of combustion of H₂ and O₂) to recombine as water vapor. The hot vapor is then fed through a condensing coil (pure copper, possibly household water pipe, no lead). Depending on how much heat is generated in the catalytic converter, a secondary vapor generator could be used to utilize the waste heat.

In this way you avoid having to heat a large mass of water. It also lets you replenish the water without concern of lowering the temperature when heated and unheated water mix.

Occasionaly you may have to replace electrodes, particularly if you have hard water and there is a quick calcium buildup on the electrode.

However, you might also need to check with the ASME if this method is legal according to their rules, since their original idea is to heat water vapor to steam, and this electro-chemical method does not do that, but could produce a similar result. If their rules require that the drinking water reach boiling temperature, then the hydrogen might be fed to a burner to boil the water for drinking.

Materials required:

• Hoffman electrolysis apparatus (Raid the Chem. Lab.)
• Sodium Chloride (to aid electrical conduction in water)
• Copper tubing formed into a coil. Immerse coil in running water to aid condensation of water vapor if water is unlimited.
• Catalytic converter (Again, raid the Chem. Lab)
• Collection container.

One other thing you might do is search CR4 for the thread related to heating milk by human power, which is very similar to the problem you posed. There were many good ideas there as well.

Good Luck!

Look around!

You have a reliable supply of water vapor right under your nose:

Your breath!

Focus on condensing the moisture from your exhaled breath, perhaps using a

reclaimed refrigerator or water-cooler coil.The air should cool as you blow thru it,

and condensate should drip from the exit end.

Be sure to thoroughly clean the coil before using it.

If asked where is the water supply, simply drink a glass of water.

Will this meet all of the project criteria? Good luck!

Obenay N. Pebvk

I think the problem remains 'where do you get the glass of water from?' As the basic assumption for needing a distiller in the first place is that all the water around you is undrinkable. While it may not be a valid approach in and of itself, it should still be valid as a conservation method. Essentially use your condensed breath to increase the efficiency of your setup. In addition to recovering the H2O in your breath you may be able to recover the heat as well. A vest made of water bladders might make a decent preheated reservoir. However as a practical mater, in an emergency flood situation it might not be a good idea as it could dangerously lower your core temp. slo

I'm not sure about trying to condense the water in the breath of a human. You would need to be absolutely certain that the didn't get it contaminated with any droplets of water that were expelled as you breathed out as these droplets can contain some very nasty things. At best they contain enzymes from saliva and bacteria from the mouth and may even contain virus particles. Any of these contaminants could render the resultant condensate anywhere between useless and deadly.

On the surface, your argument is valid, and has merit.

But after further examination, and presuming that what is not explictly excluded is included, consider this scenario:

A person breaks down on the desert.He has a 3 day's supply of water.He knows it will take at least 5 days to walk back to the nearest water supply.

He could start condening water from his breath on his first day, and thereby extend his supply.Sure, there will be bacteria, but they will be from his own system, and not likely to re-infect him, as his system is already host to them.Providing, or course,that he does not store the water long-term, which would allow certain microorganisms to multiply unchecked.The options available to him are:Drink or Die.He could also have been smart enought to carry some iodide pills with him.

There have been instances where people have survived by drinking their own urine.Not pleasant, but in survival mode, anything goes.

Consider the reliability and simplicity of this idea.

By the way, did the conditions of the experiment specify POTABLE water as a final result?

Even distilled water can be deadly in certain cases.

Obenay N. P.

The problem is turning waste water (not breath vapor) into Potable (drinkable) water by using human work as the overall source of energy to bring the waste water to the boiling point and past the heat of vaporization point so that the clean H2O vapor can be condensed and consumed by a very thirsty person. If distilled water can be deadly in certain cases then that is not what we would like to produce. This project is to provide a means to obtain drinkable water for people that would be dehidrated and in distress during an emergency situation where only contaminated water is available.

Does anyone have a suggestion on how to create the most amount of energy with the least amount of effort using the strongest muscle in the body with the smallest apparatus possible? That would be helpfull. Thank you.

EMK

Refer back to my earlier comment on using a small heater (aluminum power resistor?) and dripping water on it. With a small area you can get it to boiling with minimum energy. It isn't fast but you might generate more water than you expire while producing it. Insulate the chamber. Also, since you can have entrainment, it would be good to put an activated fiber and a charcoal filter in line to filter mist and gases from your condensate.

You are such a retard. Whatever you are doing in life, just give up now.

There would seem to be a lack of appreciation for scale and what is practical in much of this that suggests a lack of experience with real designs or anything technical.

I agree 100 percent.

Check out a camel's repiratory vapor recovery system.

The condensing could be done at night, while the outside air is very cool, which woukld reduce size and improve efficiency.

Hard to beat a sheet of plastic, suspended on 4 sticks, with a pebble in the center to create a funnel,with a container on the inside to collect the condensate that naturally escapes from the soil.Want to increase efficiency?Breath under the plastic,This will add your own vapor to it.

If you would like me to draw you a picture....

Call your next case, I'm done here.

O.N.P.

Just in case you forgot:

Water will boil at room temperature in a reduced pressure atmosphere.

Can you say Vaccum Pump?

By slightly reducing the pressure, you can reduce the nescessary btu requirement.

Add this to your ideas collection.

Good luck with your project.

CTS

Guest #26,

You bring up a good point. You can reduce the pressure with a vaccuum pump, but it will not stay reduced unless you keep the vaccuum pump running. Steam will build the pressure right back up. Yes, you have reduced the BTU requirements, but have your overall energy requirements reduced? It now takes more energy to run the vaccuum pump. Depending on whether the vaccuum pump is electric and running off a human powered generator or is strictly mechanical, e.g. pedal power turning the pump input shaft instead of a motor, and just how frictionless is the pump, there will be different levels of efficiency as compared to boiling the water at ambient pressure.

Personally, I subscribe to the KISS principle, especially given that you are trying to replace a process which normally relies on high energy availability with one with low-energy availability. Keeping it simple usually means keeping it efficient as well.

If you have a sealed system with warm point and cold point, and remove the air with a vaccum pump, then seal it and remove the pump. Apply a little heat to the warm point (body heat works) and water will collect at the cold point. Have wide tubes connecting them that will not collapse and the water will boil quite nicely at human temperature.

I get your point, but how do you translate that into an effective Human Powered Water Distiller? Please illustrate you proposed design that uses the effect you described, otherwise your posting is purposeless pedantry!

Concerning lowering the surrounding pressure to make water boil at for example a temperature of 50C is not as easy as you are making it , i have a project relating to the topic and i have reached a dead end, since 50C means 0.3bar, and the boiling point of water is at 1bar, so we have 70% reduction,I tried using a rubber sink and "de-pressurize" it using the concept of wheels, but it didnt work since I only reached a 0.7bar pressure :S. I dont know about the vaccum pump thing but i think you will have a hard time pedaling to keep it running.

I may suggest that you check the seebeck effect or the jet effect used in agriculture. I am doing some reaserch in this field and i will keep u in touch with any improvement.

Gdluck

I would have to concur and re-iterate my comment in posting #24. Pulling a vacuum is not as easy as one might think and it gets progressively harder pretty quickly. Also remember, there is no free lunch! It's not like you are going to find a particular way that takes tremendously less energy. Use a generator. Use a small but hot resistive heater in a chamber linked to a condenser. Drip water onto it so that it vaporizes immediately. Now you don't have to generate a large amount of power to run the process. Want more water? Run the process longer. Distilled water, on demand, albeit at a small but steady rate.

I am also in a group that will be competing in the ASME contest next year. You first need to understand the contest rules, then you and your group members need to become experts on the subject of water distillation and everything involved with it. If you plan on being competative. You should stop asking everyone to do your project and become an expert on the subject yourself. Noone knows much about this subject because it hasent been done before. Nothing on this post is anything that we havent found out ourselves. As a matter of fact, we problably know more about this than any engineer that has posted or will post on this site. And to that person that commented on heating the water with your breath, you and your group are going to have some serious problems if you serioulsy consider that. Most of the people that posted forgot about one simple thing that none of us can avoid. You cant get around this and if you forget about it, your going to be stuck when you start your fabrication. Good Luck, because you will need it.

Very good point. I am a big fan of not asking others for help. I learned early on you mostly end up copying mistakes. I think I learn more easily from my own mistakes.

Guest #32,

I am curious. Are you saying that the solution proposed by RCAPPER for "distillation on demand" would be in violation of the ASME rules? How would that be?

You said, "Most of the people that posted forgot about one simple thing that none of us can avoid. " Then you did not tell us what that is. Are you being deliberately mysterious because you are afraid you might tip some big secret to the guy on another team? Oh, come on, really?

Also, in your opinion, whether or not it would actually work, does my proposed solution in #19 above, to use electrolysis to break water into H₂ and O₂ gases, then recombine them as pure water vapor, violate the ASME rules? Is it an absolute requirement that the water reach vapor phase through heating only?

It seems to me that this solution would still be in the spirit of the rules, to produce pure drinking water through use of human power only, if not to the "letter of the law", i.e. if "boiling" is a requirement.

Let's go back to the right track and keep things as professional as they SHOULD be;

I was curious to find the solution for the contest and for "whom is worried, dont!! I am not going to be contesting for ASME!!"

Anyways, I narrowed my choices into 2:

1- Charging a battery from a mechanical power (pedal most probably..)

2- Using the Friction concept.

But I was wondering before getting started, I am still a lil' bit lost concerning charging a battery, how accurate can it be? and how can we charge it in the first place?

And Concerning getting heat from friction, should I go for planar contact surfaces or a shaft fitted inside a fixed hollow copper cylinder?!?!

HELP!!

There is a bloke in the US that manufactures a heater that consists of a rotating impeller inside a drum with indentations in the drum and impeller. It can produce anything from hot water to steam and he claims that it is more than 100% efficient. Personally I find hard to believe but even so I would suspect that this would be the most efficient way to go. Charging a battery is at best about 80% efficient and that's before you take into account the efficiency of the generator and charging circuit.

I appreciate your input and interest in this discussion however I have only asked for suggestions on vendors or places to acquire components. Please direct me to where I have asked others to do my work for me. If by asking for vendors, you consider doing my work, then I apologize I don't know many vendors that carry generators. On another note thank you all for your replies and input, we are pretty much set on our design. We are currently in the process of constructing our device. The generator we purchased is producing less then desirable results. If anyone knows of any low RPM and high voltage output generators please feel free to chime in.

That may not be a practical configuration in a small device. I would suggest you use gears or pulleys to boost your RPM.

Thank you, Someone has some common sense finally! I will also be competing at the ASME competition and for all that have replyed to this forum hopefully at least the profesional engineers have skimmed thru the 2007 ASME design competion rules and regulations and if you haven't then you need to before replying to anyone else. You cann't possibly make any suggestions or answer any questions without a proper understanding of what is trying to be accomplished. All that is being asked for those willing to give a few pointers is that you read over the ASME Rules and Regs and if you have any ideas, thoughts, knowledge of a good vendor, let us know.

EMK

http://www.asme.org/Events/Contests/DesignContest/2007_Design_Problem.cfm

One issue that may not effect the contest but would be important to look at in a practical sense it that a human applying significant effort can easily loose over a pint of water per hour. I don't know what the limits are but it should be considered in the ultimate application of such a device. It would be of little benefit to employ a device that dehydrated you faster than it made water for you to drink!

I am the infamous guest #32. from the tests we ran, we found that we have to give up something to gain something. we are putting a certain # of watts in to boiling and condensing water. If you want to add a vacuum, you are taking away the amount of heat you can put into the system and vise versa. It's a matter of balance. For those of you that haven't read the rules; we have constraints of size, weight, no filters, only human power, and the water has to be boiled. Part of the score is based on how hot we can get the water. And of course I wont give up the secret, I wish you the best but this is a competition. And don't expect to distill gallons of water. There isn't a system that works on less than 1000w that will produce more than about a liter/hour