Student Propelled Water Heater

Hello,

It sounds like you are having fun and it is one of the best ways to learn. Take a step back and see what is going on. Where is the heat being generated? What is generating it apart from your bicycling energy. Ask yourself what kind of heat it is?

Having found the source of the heat, imagine how you could generate similar heat using different materials.

Do this simple experiment. Take a bicycle pump and pump up a tire or ball. Feel the pump! what caused the heat.

Ask yourself would a thin tubing or multiple coils of thin tubing exposed to such heat, heat the water faster than one larger Tube.

Try rubbing different materials on your hand and then the tubing and see the results.

Keep us posted on the direction you are taking. Sometimes we tend to keep digging a bigger hole, instead of reflecting on where we are and what the goal is.

Good Luck. Young Engineer.

Yea sounds like a good idea. Ive tried putting a layer of steel wool inbetween the two shafts but that didnt work because the steel wool would ball up and hinder the movement. I also tried using sandpaper as an outer casing also and that didnt work because it fell apart after two or three tries with it. I also tried rubber but the ruber created too much friction and that made the inner tubing not spin at all. Thanks for the idea and ill try getting some other materials too work with and see how they react.

Hello Jordan, welcome to CR4.

This thread was posted by a young student who was basically trying the same experiment as you! Check it out, there are some excellent ideas posted by some of the folks on here! Let us know what you think!

Hello lonelysoul.

When you say student propelled you mean student powered?

If I were trying to heat water using a bike's mechanics, I think that I would use the bikes generator to charge a battery and then dump the elctricity from both the battery and my pedaling the generator through a resistive heating element.

This would also teach you about load, and circuits, and you would know when the battery was drained because the pedals would suddenly become quite difficult to turn...

This idea would work as long as the assignment wasn't specifically to use friction for heating.

Sounds like an interesting project.

Please give us a report of your progress!

milo

Hello Milo,

I see the little avatar grew up fast. Does she qualify as a a 'GEE A'

I read only one week ago, the story behind the wee avatar, so I will be waiting for an update.

By the way your answer should spark some research by the OP.

Good Luck

by propelled i do mean powered. I like the idea with the battery and going from there but, in the rules you cannot use any means of energy besides energy produced by yourself. Also all energy must be made in view of the judges. (just to let you know im doing a physics 'olympics' assignment) Otherwise that idea would be great. Also to give a little more insight into the project i must take 750 mL of water at room tempature (aprox. 22C) and get it as close to boiling point (100C) in 5 minutes. That includes setting the apparatus up and getting it going. right now im using a tubing that holds about 500 mL of water and starting it at room tempature (aprox. 22C) and with the rig that i have now im getting about 5 degrees in the 5 minutes. I know that with bigger tubing and more water it will not heat up that much so i need to improve the use of mechanical energy. One thing i would like to try is to get a tube that is made of steel for the inside and a PVC tubing for the outer tube that way there is a bit of insallation without me adding a lot of extra. Im ussing a gear from combine that is aprox. 23 cm. in diameter. I have taken a chain that goes from that gear to a smaller gear that is aprox. 10 cm. in diameter and that gear is attached to the iner tube. This is great for rpm but when applied to great of friction the smaller gear will not be spinned by the larger gear. If you have any ideas about how to maximize those rpm's that would be very usefull.

I think we might have something here start off with the water circulating a suit worn by the student while pedaling a bike powered generator charging a big capacitor you could short this out at the start to prove that it is empty then with the water pre heated by the student body heat put it into a insulated vessel at about 4 min with a heating element powered by the bike generator and the stored energy in the capacitor for the last minute to heat it the rest of the way ther by using the body heat generated by the student and the mechanical turned electric turned thermal energy from the bikeI think this would be a nice combination of the already suggested ideas

and for a new idea a rotating cylinder with a strap like those used to hold luggage down on a trailer held round it by the tension of a spring my mother once has an exercise bike that had a strap like this held on the rim to create a load to pedal against the rim got so hot after a minuit or so it could give revier burns

excellent idea. GA

GA, I was going to suggest similar process. Look at the overall energy usage, not only the hot pot.

I must apologize..somehow I missed that you had a prior suggestion of tapping the student for heat.. so a GA for this innovative thinking.

Chris

I recall seeing a documentary some time ago about a water heating system which used just mechanical power. As I remember it consisted of a cylinder with another perforated cylinder rotating inside. The device had been installed in an American fire station to provide all of their hot water with claims of great efficiency.

Thinking back, the device seems like a torque convertor in construction but, with no output, all of the input energy is converted to heat.

cavitation water heater

First calculate how much energy you need to boil 700ml of water in 5 min. Then look into how much energy your "friction heater" is generating now. See if its possible to increase it to boil water inn 5 min. Look into other method of heat generating to see which one is more likely to success. If you stir the water fast enough, you can heat it up also. You can also combine different method to get better efficiency if its allowed.

If you want to use Friction to produce the heat, try using a Spring to control the loading of the rubbing parts. Make the spring tension adjustable and record the amount of heat (water temperature rise) at various settings. Graph Water temperature (Y axis) vs. Spring force (or setting). Is there a maximum or minimum? How does the match between your pedaling ability and the drag load affect the results?

Try various materials against each other, but metal-against-metal should give good results. Maybe use that as a baseline.

All the ideas put out there are really good but all energy must come from friction. The idea about the student heating it through body heat is really good. I wish i could use it but the rules say i cant. Keep the ideas coming! These ideas are awesome!!!!!

"you cannot use any means of energy besides energy produced by yourself."

the rules as posted do not seem to rule out direct thermal transfer from the student..so you should maybe print the Exact rules for all to see... that would eliminate the guesswork.. they should have been in the original post don't you think? to not waste time...

Chris

Okay yes i will do that. Sorry about all the running around but im new to this. The rules are as follows -

4. STUDENT-POWERED WATER HEATER. Each team shall construct a device that will hold and heat 750 ml of water. During the competition only the two (2) team members may be involved in the activity.

The officials will be certain that the water to be used in the competition is placed in the competition area overnight to make certain that it reaches room temperature.

1. Only human body energy supplied by the two students will be the source of energy. This energy may be changed to other forms in order to heat the water. No energy may be added from other sources. No chemicals or solar energy may be used.
2. No material substance can be added to the water.
3. The test water will be tap water provided at about room temperature and will be measured out by the judges into an insulated container.
4. Just prior to a team trial the temperature of the water in the judges container will be measured and the timing will begin.
5. Timing begins when students take possession of the water.
6. To eliminate transfer of body heat to any part of the device, no person may hold, or come in contact with, the device until the judges call the event team to the competition.
7. All components of the device must be visible to all viewers.

The Competition – Timing begins when students take possession of the water. At the end of the 5 minutes, the water will be returned to the insulated container and the temperature determined. If more than 50 ml of water has been lost during the competition, room temperature water will be added to bring the total volume to 700 ml before the temperature is measured. Otherwise the thermometer will be inserted immediately into the original container at the end of the 5-minute period, after stirring to assure a uniform temperature, and the highest point recorded. The winner will be the team that increases the temperature of the test water the most in 5 minutes, or that is able to heat the water to 100^o Celsius in the shortest amount of time less than 5 minutes.

so you CAN use body heat.. just not allowed to preheat the suit by wearing it before the start of the competetion. this should be at least part of your design, because otherewise you are wasting the heat developed by the muscles. there can even be a claim made that body heat is created by friction after all..the friction of muscle cells.. and if that is disputed, i would force them to prove it.

so a combined approach, part body heat, part friction or magnetic generator. that should put you in the top group. lastly, you will be transfering the water to your system.. make it a closed loop so you don't lose any to atmosphere, even at boiling temp.

good luck

Chris

Hmmm. nice idea. Now with me being able to use two people..... would it be possible to make it a way where the water could circulate through the body suit and the tube without the circulation between each other disturbing the spinning tube? or would it be easier to put some water in the body suit and some in the inside tube and heat each other at different speeds?

Okay. Well i apologize for the running around and another user has brought it to my attention that it would be more convenint if you all have the rules. These rules are for the 2008/2009 Iowa Physics Olympics. These rules are most likely going to also be used for next year so hear they are:

4. STUDENT-POWERED WATER HEATER. Each team shall construct a device that will hold and heat 750 ml of water. During the competition only the two (2) team members may be involved in the activity.

The officials will be certain that the water to be used in the competition is placed in the competition area overnight to make certain that it reaches room temperature.

1. Only human body energy supplied by the two students will be the source of energy. This energy may be changed to other forms in order to heat the water. No energy may be added from other sources. No chemicals or solar energy may be used.
2. No material substance can be added to the water.
3. The test water will be tap water provided at about room temperature and will be measured out by the judges into an insulated container.
4. Just prior to a team trial the temperature of the water in the judges container will be measured and the timing will begin.
5. Timing begins when students take possession of the water.
6. To eliminate transfer of body heat to any part of the device, no person may hold, or come in contact with, the device until the judges call the event team to the competition.
7. All components of the device must be visible to all viewers.

The Competition – Timing begins when students take possession of the water. At the end of the 5 minutes, the water will be returned to the insulated container and the temperature determined. If more than 50 ml of water has been lost during the competition, room temperature water will be added to bring the total volume to 700 ml before the temperature is measured. Otherwise the thermometer will be inserted immediately into the original container at the end of the 5-minute period, after stirring to assure a uniform temperature, and the highest point recorded. The winner will be the team that increases the temperature of the test water the most in 5 minutes, or that is able to heat the water to 100^o Celsius in the shortest amount of time less than 5 minutes.

Hopefully this will help all of u that are helping me. THANK YOU AGAIN FOR ALL OF THE HELP!!!!!!!!!!!!

My inclusion of using body heat as the primary source seems to have lead the discussion down a confusing path.

For a moment, lets forget about getting heat from the students body (even though this is a great source). Huge gains in efficiency are available by designing around the idea of a heat pump rather than a resistance heater. It typically requires far less energy to move heat from one source (ambient air) to another source (750ml water) at a similar temperature than it does to cause a similar increase in temperature in the second source by resistance heating alone, be it electrical or friction.

The important point to ask here is 'why go through all the effort to create something that is in already in abundance when it can more easily be moved?'.

At the very core, using a vapor compression cycle to heat the water can give you a far better chance at reaching 100C in 5 minutes than most other methods, even drawing heat from the ambient air.

So if you want to add back in the ski suit later that should help, but lets consider a very simplified version.

- an aluminum tube long enough to hold 750ml water, with fitted end caps. Wrap copper tubing to completely cover the aluminum tube. Insulate the entire wrapped tube and make insulation for the end caps. A smaller diameter tube should be better as more surface area per milliliter, but you must be able to wrap the copper tubing effectively and too small a diameter may cause difficulty here. You might consider using a heat transfer compound when wrapping the aluminum tube with the copper tubing so that the effect of voids will be lessened). .... The copper tubing becomes the condenser in the vapor compression cycle.

- a flow restriction plate or flow restriction valve, across which a large decrease in pressure can be developed by....

- a compressor, connected to the bicycle crank or sprocket gears and powered by the student.

- a radiator and fan (also turned by student power) through which the refrigerant flows after passing the flow restriction plate or valve. This is the evaporator of the vapor compression cycle. The fan does not need to be high power, just enough to keep some air moving through the radiator.

The specifics of the design are going to vary significantly depending on your choice of refrigerant, which could be any number of substances that change form liquid to gas near the temperature ranges in mind. Ammonia, any number of refrigerant gasses, or even water are among the possibilities.

It would be nice to find a small refrigeration unit that already had the refrigerant sealed. Something like a small cooler i sometimes see that was built to hold 8 - 10 bottle of wine, would be a great find.... perhaps Craigs list?

This set up shoudl allow you to heat the water much more efficiently than by friction. If you want to increase the efficiency then you've got the heat coming off the student available.

Hi Jordan,

Welcome to CR4 with your problem.

I think the transfer of body heat has merits but I dont think it is going to give you the highest temperature. Given that normal body metabolism temperature is around 36C (98F) and in fever condition around the low 40s, is it likely you would achieve body temperature up to 50C even before you could transfer the heat to another medium? It is probably worth considering this approach if the target was to heat the largest volume of water rather than achieve highest temperature.

For this I think your best bet is through maximum friction and the body energy to exert maximum friction in the 5 minute test period. Consider a 10" (250mm) flat surface circular sanding disc, the type used in a woodworking lathe in constant rotational contact to a thin bottomed highly conductive container (pot or saucepan) to obtain the best heat transfer. There are two persons, so 375ml each, (say 5-10mm water height) both peddling like hell for 5 minutes or until you disappear amid a saturated cloud of water vapour.

How much energy can you exert over 5minutes, diameter, force and grit size are probably the important inputs. A few trials should sort these out.

Good luck.

Use some sort of metal finned heat sink in the bottom of the container to transfer as much of the heat to the water as quickly as possible.

The more surface area of your heating source that is in contact with the water, the better.

How come they never had fun projects like this when I was in school?

Given the above rules, I would now like to submit the following idea.

I would attach a jacobs chuck to the gear at the end of the bike pedals. I would put a dull wide margin drill in the jacobs chuck. I would put a piece of aluminum (bar say 12" long and 1-1/2 or 2 inches round) into clamping device below held in insulated jug like a thermos into which which the water will also be poured, Drill into aluminum will create frictional heat and chips. Aluminum conductivity will transfer heat to water, as will hot chips falling therein.

If drills break, put them in water to collect their heat.

If you have a means of circulating the water into the cut that would be good too .

I would put the aluminum held in clamp in jug on a platform which can be raised by the non pedalling team mate (Like on a scissors jack or bottle jack to provide feed into the drill held rigid) who would also be circulating the water.

And I would increase the drill margin to increase friction and heat.Most heat will be in the chips. so letting them fall into the water is important.

DRILLINGALUMINUM

Milo

physics hadn't been invented yet!?

I am not ~that~ old... although I do remember one guy I worked with out of college who always referred to capacitors as "condensers".

My original thought would be a slush box. Less mechanical components would mean more efficiency. However, the idea of using the heat from an air compressor is very interessting. My shop compressor heats up to +200 C in only a few seconds, and if I am using it a lot, the whole tank heats up. There seems to be a lot of energy in ambient air. I think I should look into that.

The energy is from the compressor compressing the air.

I won't connect the water to sutdent body if the goal is to boil the water.

that's a good idea.