Solar-driven Stirling engines for electricity generation

The "Picture of the Day" in today's New Scientist shows a solar power generation test using Stirling engines as the generators.

Topic by kelseymh 9 years ago  |  last reply 9 years ago


Is it feasible to use plastic as the material casing for a miniature fan driven jet engine?

I would like to use an old cpu fan and some old 2 liter soda bottles to experiment jet engine designs. Using lighter fluid for the fuel and probably running the engine in short bursts just to measure thrust output, it should be strong enough to survive at least several runs without dramatic failure right?

Question by 10 years ago  |  last reply 10 years ago


could anyone recommend a steam engine? Answered

I saw crazybuilders instructable on making a propeller driven skateboard, and that inspired me to make a prop driven gocart. I have also recently become interested in steampunk and I thought it would be awesome to use a small steam engine to power it. This is where it gets difficult. Could anyone recommend a steam engine powerful enough to drive two propellers fast enough to move me? (I weigh about 50 kilos)

Question by scarabeetle101 10 years ago  |  last reply 8 years ago


What kinda engine would be suitable for a moped bike?

I am looking into making a moped out of my bike to increase fuel efficiency. I am looking to find out where i could find a suitable engine within laws for NH. Around here, According to the DMV a moped or scooter must meet the following restrictions: It must have an engine of 50 cubic centimeters or less. It cannot exceed 30 mph on level terrain. It cannot shift. It cannot exceed two horsepower. As i said, im not sure where to find a suitable engine to meet those criteria that i can scavenge. I am looking to make a chain drive bike not a roller driven due to inneficiency,maintence,and traction of the roller on the wheel being lack. Couldnt find any chain driven conversions on here. If you can offer any information it would be much appreciated.

Question by trf 8 years ago  |  last reply 8 years ago


chain driven weed whacker bike

I am currently trying to complete a weed eater bike build, but have run into some trouble. a jackshaft is required, but i do not have enough money to purchase a kit or use a welder. built one out of some bolts, bearings, and the sprockets needed for reduction, but the engine shakes the chain off the primary drive sprocket or the primary driven sprocket when it is operating. i also need to figure out a way to mount the secondary driven sprocket to the wheel, would JB weld or something similar work? thanks in advance for any help and/or ideas

Topic by Badetise 5 years ago  |  last reply 5 years ago


Drinks can Stirling engines (UK & EU only)

These are simple coke can Stirling engines that run on one or two candles. Made from recycled coke cans, tuna cans and bottle lids. They are of a simple gravity driven design that using fishing line to connect the displacer. Each on is made by me and slightly different, so the pictures are guidelines only. Please not these are just models will not power anything useful (as far as I'm aware!).  They are £8.99+ £1.98 shipping. For more details, see my site here. (video shows slightly older version, these run the same though)

Topic by scraptopower 8 years ago  |  last reply 8 years ago


93 ford ranger 4.0 v6 ac compressor into engine driven aux air ?

For my air ride system

Question by jjhaney 7 years ago  |  last reply 7 years ago


How to convert a gas powered air compressor to electric?

I have an old gasoline engine powered, belt driven air compressor on which the the engine no longer works. Does anyone know of a way to convert it to an electric compressor I can use in my shop? I'm guessing I could remove the engine and use an electric motor, but am not sure how to make the motor shut off when the tank reaches pressure, how many rpms the motor needs to do, or even what kind of motor I need to look for. Thanks for any help you can give me!

Question by WMProgram 7 years ago  |  last reply 6 years ago


World's Heaviest Motorcycle

Monster bike is world's heaviestA giant motorbike powered by a Russian tank engine has been recognised as the heaviest in the world.It's been dubbed the Led Zeppelin by creator Tilo Nieber, 39, who said: "You don't get much more heavy metal than this."The four-and-a-half tonne machine has driven into the Guinness Book of Records as the heaviest motorbike in the world.It is 17ft 4ins long and 7ft 6ins tall and the engine alone weighs 1.8 tonnes after the armour plating tank cover has been stripped off.The bike, which took a team of welders and mechanics almost a year to build at the Harzer Bike Schmiede in Zilly, Germany, is now hoping for a licence to travel on the road.But in the meantime Guinness Book of Records spokesman Amarilis Espinoza confirmed it was the world's heaviest motorbike.

Topic by ewilhelm 11 years ago  |  last reply 9 years ago


Supercharger anyone?

Has anyone built or knw how to build a small efficient supercharger for a car. It has to be engine driven and not electric. I do not want complexities like electromagnetic clutch for the supercharger if its ok to have some boost at idle speeds. I am looking to supercharge an 800cc Suzuki engine for betr performance.

Question by sankyp 9 years ago  |  last reply 9 years ago


turbo two stroke?

How would you put a turbo on a two stroke? what i want to do is a strictly electric driven one rather than exhast driven because i dont want to have to deal with all the small stuff and the engine is only 25cc if i cant do it do you have any suggestions on how to up  the hp?

Question by BIGHAIRYDUDE 8 years ago  |  last reply 8 years ago


Octopart - search engine for electronic parts

Two weeks ago I met with Andres and Sam of Octopart. Andres had literally dropped out of graduate school the day before to join Sam full-time building their search engine for electronic parts. You enter the part number, or simply its title or use, and Octopart returns the best matched specific components, their prices and availability from several suppliers, and links to the relevant catalog pages. I wish this had existed back in 1998. At the time, I was in charge of building the power controller for a web-controlled, wireless robot with a live video feed as part of the ultimate class in MIT's undergraduate mechanical engineering program, 2.009 Product Design. What is now a relatively easy task, was really kicking my butt then. After two painstakingly hand-built MOSFET H-bridges driven by charge pumps had exploded in my face, I was at my wits ends. I knew there had to be a better solution, but could not find it anywhere. At one stage, I even sat down with the Digikey catalog, and started reading through all of the components in the sections I thought might have something relevant. Pop "h-bridge" into Octopart and the fourth result is my favorite chip (and what eventually saved my skin in 2.009), the LMD18200. Hey look, the cheapest price with the highest availability is at Digikey, I think I'll get it there...Octopart is pretty cool as is, and I'm sure there will soon be lots more distributors. What's even more exciting, in my opinion, is the concept of Octopart searching through a webpage, determining what specific parts are mentioned, and generating a personalized shopping cart with the cheapest and most readily available parts. When we spoke, Andres and Sam said it might be a few months until they were ready to release at all - it would seem quiting grad school has been good to Octopart, so I'm sure cool new additions are right around the corner.

Topic by ewilhelm 12 years ago  |  last reply 11 years ago


Solution to turning on/off gas: new pump design.

I've been working a couple weeks now on solving the problem I posted here on how to improve my pump design by alternating the feed of ethanol vapour. I got good feedback but ultimately all the solutions involved mechanisms which were going to be somewhat tricky to build and source, which is against the brief of the project I'm working on; being an open source solar tracker concentrator makeable from scrap. In the end I solved the problem by largely redesigning the whole pump. Since it's driven by boiling ethanol, rather than add an extra mechanism for turning the feed of vapour off and on, I reduced the amount of ethanol being boiled, so that it boils itself out after an appropriate period. The vapour is then able to collapse fully, which sucks in more liquid ethanol and refills the system. 1. At the bottom right is the boiler, which holds about 2-3 ml ethanol. 2. This boils and the vapour enters the 'chamber' (the half blue, half white (liquid and gas)), forcing out the liquid, which pours into the wheel, ending up in the main reservoir. 3. This continues until the eths in the boiler has boiled away to the extent that it can no longer overcome the rate of re-condensation in the chamber, which starts to suck, so to speak. 4. This draws liquid from the reservoir, which passes through the boiler, shutting off the boil, the pressure drops quickly and the chamber and boiler refill with liquid. 5. Two valves (the only moving parts, besides the wheel) keep all this going in the right direction. 6. Repeat. The wheel provides the motion for the solar tracker. It's not in by any means powerful or efficient, but the whole thing can be made from a bit of metal tube, some thin pipe, a glass jar and two valves from bike inner tubes (plus a paint tin, bike wheel bearing and some drinks cans for the wheel). I haven't had a chance to try it in the field yet, but powered by a candle it seems to work fairly well. Blog entry here, will post photos and videos when available.

Topic by SolarFlower_org 8 years ago


Can you check this design? Answered

On Aug 26 I posted an ask about a design of a new type of motor.  I received some good advices. Redesigned 02/10/12 The previous design had a major flaw, that went unnoticed at first but it became clear as I went into the construction of the prototype: the thermal barrier would be totally useless, because the steam produced in the boiler necessarily have to go through liquid water to make its way into the compression chamber. This would have two disabling consequences: 1) the vapor would cool quickly, 2) the water would heat up quickly, too. Since any heat engine operation is based on temperature differences, this failure is vital. The new design does not have that problem. The water falls directly into the hot boiler, a small amount at a time, with the piston in the upper dead point, or below (note that my drawing is reversed with respect to what would be a conventional combustion engine). The water is kept cold by being stored in a separate reservoir, attached to the motor body only by the inlet and outlet pipes. Water injection is performed by momentarily opening a valve at the appropriate time. Since the interior of the water reservoir accumulates pressure as the engine works, this pressure would be in principle the responsible to force the output water through the tap. If that's not enough, I could add a little manual compression pump to initially load the reservoir with compressed air. So once the Primus heaters worked, which were extremely useful for decades. The exact moment, quantity and duration of water injection should be adjustable during operation of the engine, to find the optimum point for these parameters. These mechanisms have not thought of yet, but they can not be too complicated. As regards the boiler, it is likely that one heated surface be insufficient to rapidly vaporize the water, since in these conditions it usually adopt a globular shape that greatly retards heat transfer (Leidenfrost effect, http://resnickscity.wordpress .com/2011/01/page/3 /, http://es.wikipedia.org/wiki/Efecto_Leidenfrost, http://en.wikipedia.org/wiki/Leidenfrost_effect). I think that could be solved relatively easily by a double bottom to the boiler, in order to "force" the water into laminar contact with the hot surface. If this is insufficient, it would still be possible to inject the water by pressure between two heated surfaces. I have to also investigate the possibility of to make "super hydrophilic" the surface of the boiler. Regarding the compression chamber, this design makes it much longer, thus establishing a better differentiation between the bottom hot and top cold. But the main novelty is that the displacer stops acting on a small amount of water to turn acting, as in the Stirling engine, on the entire volume of the steam in the compression chamber. By forcing the steam to move towards the cold zone it produces its condensation, thereby changing the pressure by decompression, and so completing the cycle of the engine. The condensation water adheres to the cold walls of the chamber, then it slides down by gravity, and is intercepted midway by the retaining ring, which leads it back to the water reservoir through a single action valve, spring driven. I guess that to pass the water to the reservoir will be enough the vapor pressure that occurs in each cycle. The accompanying drawings are quite precarious, but only pretend to give a general idea of the design. Please ask me if you want more details ------------------------------------------------------------------- Nuevo diseño 02/10/12 El diseño anterior tenía una falla importante, que me pasó desapercibida al principio pero se hizo evidente a medida que avanzaba en la construcción del prototipo: la barrera térmica iba a resultar totalmente inútil, dado que el vapor producido dentro de la calderita tendría que atravesar forzosamente el agua líquida para abrirse camino hacia la cámara de compresión. Esto tendría dos consecuencias inhabilitantes: 1) el vapor se enfriaría rápidamente; 2) el agua se calentaría también rápidamente. Dado que el funcionamiento de cualquier máquina térmica se basa en las diferencias de temperatura, esta falla resultaba vital. El nuevo diseño no tiene ese problema. El agua cae directamente dentro de la caldera caliente, una pequeña cantidad por vez, estando el pistón en el punto muerto superior, o sea abajo (ojo, que mi dibujo está al revés respecto de lo que sería el de un motor a explosión convencional). El agua se mantiene fría, por estar guardada en un reservorio separado del motor, unido a él solo por los caños de entrada y salida. La inyección de agua se realiza mediante la apertura momentánea de un grifo en el momento oportuno. Dado que el interior del reservorio de agua acumula presión al funcionar el motor, esta presión sería en principio la encargada de impulsar la salida del agua a través del grifo. Si esto no fuera suficiente, habría que agregar una pequeña bomba manual de compresión para cargar inicialmente de aire comprimido el reservorio. Así funcionaban antiguamente los calentadores Primus, que fueron sumamente útiles durante décadas. El momento exacto, la cantidad y la duración de la inyección de agua deben ser regulables durante el funcionamiento del motor, para hallar el punto óptimo de esos parámetros. Esos mecanismos no lo he pensado todavía, pero no pueden ser demasiado complicados. Respecto de la caldera, es muy probable que una sola superficie recalentada sea insuficiente para vaporizar rápidamente el agua, dado que en esas condiciones esta suele adoptar una forma globular que retarda mucho la transferencia de calor (efecto Leidenfrost, http://resnickscity.wordpress.com/2011/01/page/3/, http://es.wikipedia.org/wiki/Efecto_Leidenfrost, http://en.wikipedia.org/wiki/Leidenfrost_effect). Creo que eso podría solucionarse con relativa facilidad haciendo un doble fondo a la caldera, de manera de "obligar" al agua a establecer contacto laminar con la superficie caliente. Si esto fuera insuficiente, siempre quedaría la posibilidad de inyectar el agua a presión entre ambas superficies recalentadas. Tengo que investigar también la posibilidad de hacer "súper hidrófila" la superficie de la caldera. Respecto a la cámara de compresión, este diseño la hace mucho más larga, estableciendo así una mejor diferenciación entre la zona inferior, caliente, y la superior, fría. Pero la principal novedad es que el desplazador deja de actuar sobre una pequeña cantidad de agua para pasar a hacerlo, como en el motor de Stirling, sobre el volumen completo del vapor contenido en la cámara de compresión. Al obligar a este a desplazarse hacia la zona fría produce su condensación, cambiando así la presión por descompresión, y completando así el ciclo del motor. El agua de condensación se adhiere a las paredes frías de la cámara, resbala luego por gravedad hacia abajo, y es interceptada a mitad de camino por el anillo de retención, que la conduce nuevamente hacia el reservorio de agua a través de una válvula de simple acción, a resorte. Supongo que para hacer pasar el agua al reservorio será suficiente con la presión de vapor que se produce en cada ciclo. Los dibujos adjuntos son algo precarios, pero no pretenden más que dar una idea general del diseño. Por favor, pregúntenme si quieren más detalles.

Question by rimar2000 6 years ago  |  last reply 6 years ago


Weed Whacker-Powered Bicycle

This is a bike I built a year ago. It uses a 30.5cc (about 1.5hp) weed whacker engine for propulsion. A version of the same thing was on Instructables, and that's what partially inspired me to make this. ;) The engine mounts are made out of wood, because I still have not learned to weld, but they hold up just fine. The engine is an ten-year-old Echo weed whacker. It has 10,000 max RPMs. The bike peg attached is 2" in diameter and gives about 25mph top speed. There is no clutch! The one that came with the engine was way too flimsy for a vehicle like this so I took it out. Saved a lot of space, too. For the throttle, I disconnected the back brake line and connected it to the engine. The front brakes are still intact, and you can turn the engine off to slow the vehicle as well. I added the extra heatsink to the engine to help keep it cooler, as it was never meant for this kind of exertion. It gets as hot as the engine, so I guess it conducts the heat away pretty effectively. There is a 10-LED bargraph to show the engine temperature. It uses an LM3914, an op-amp, and a thermistor. There is also a 555 to drive a buzzer when it gets too hot. The bike has head and taillights that are both driven from a joule thief. They are not very bright; they are more for being seen than to see. Here's a youtube video, taken almost a year ago: http://www.youtube.com/watch?v=bdySFqmK0Fw Some more photos and a little more information: http://forums.modretro.com/viewtopic.php?f=3&t;=656 Comments/criticisms? :)

Topic by 1up 8 years ago  |  last reply 8 years ago


How to design and build a belt driven generator for a small tractor?

The storm that swept through Ohio last Friday (seems like an eternity ago) took out our power. It may not be restored until sometime next week (ah, life in the country). We are used to this sort of thing in the winter and are prepared for it. However, we are not prepared to deal with it when it is this hot. I have a small generator that can run a fan and a few lights and am prepared to sacrifice the contents of the fridge. My generator doesn't put out enough power to run a window AC unit much less our central AC unit. My neighbor has a gas powered generator that is big enough to do the trick but he is pouring so much money into the tank that he might as well stay at a hotel. So anyhow I looked into getting a PTO driven generator to run off my Kubota BX1500 (think diesel engined, 4wd lawn mower on steroids rather than tractor-it's a tiny little thing). It really doesn't burn all that much fuel and it offers the option of using home brewed biodiesel (damn the Tax Man-full speed ahead!). Here's the rub though: you need about 2 hp/kw to run a generator off the PTO. My Kubota has about 12.5 hp. The smallest PTO driven generator I can find (Norther Tool) is a 10 KW unit. That won't work out very well. However, they also have a 2900 watt belt driven generator head that would be large enough to do the job. I suppose I could mig together an angle iron frame that will hook to the three point hitch and mount the generator head and the driven jack shaft but I don't have any experience in building belt drive units. Soooo, anybody out there have any experience in cobbling together belt drive units from scratch? The tractor's PTO shaft turns at 540 rpm but the generator really won't work right unless it turns at least 3600 rpm (interestingly the ratio works out to be 6.66 to 1, possibly not a good omen). Grainger has a large (if over priced) selection of pulleys that will get me in the ballpark. This still leaves a lot of questions though, probably more that I can think of since I have no experience in belt drive systems. I am specifically worried about how to set up the necessary bearings to support the jack shaft that connects the PTO shaft to the drive pulley. For that matter I don't know where to get a shaft that has PTO splines on one end and a keyway on the other. In any case, one of you guys have probably already done this or something pretty close to it. So how about letting the rest of us in on all the necessary tricks? Thanks!

Question by Ogg1 6 years ago  |  last reply 4 months ago


Phasma - biomimetics as art

On the face of it, Phasma is just another hexapod robot. Get a bit closer, though, and see an interesting difference: it has cable-actuated legs.  Driven the same way as bicycle brakes, they have rubber "knees" to redirect the basic pushing action into useful motion. Speaking of the motion... The whole thing is mechanical in the extreme, but the bouncing cable-drives and scurrying action are very "live".  If this thing ran across my floor, I'd swat it in no short order. Takram Engineering via Notcot.

Topic by Kiteman 8 years ago  |  last reply 8 years ago


How do i make a tricycle move on a track with battery power?

I do not know anything about engineering, but I want to make a tricycle move, by battery driven motor, on a track. We are thinking that something along the lines of a childs battery operated ride on train would be the route to go and it includes a decent size track, but are unsure if there is a better, cheaper, or easier way that we should do this. No, this is not for a child, it is for a halloween decoration. Any relatively simple answers or a point in the right direction would be helpful.

Question by ACurr0321 6 years ago  |  last reply 6 years ago


Crazy fun, or a slow cruel death - I can't decide...

This is just crazy - two Ocean Engineering students created a "hamster-powered submarine" from "materials derived from common household objects" that connected a hamster wheel in a sealed, air-supplied vessel to a propeller, allowing hamsters to take themselves on aquatic jaunts.  (via BoingBoing Twitter feed) Seriously, it's a submarine powered by a hamster in its wheel.  I can't decide if the hamster is having loads of fun, or is being driven mad with terror. It doesn't seem very fast, though... They documented the build on their own website, but if you would like to see an instructable on it, go to the video and leave a comment to say so...  

Topic by Kiteman 7 years ago  |  last reply 7 years ago


How to Generate low pressure air 0.8 psi for pallet gardens? Stirlinge engines, fluidyne? How?

My pallet garden project is a big success. It works great and it is becoming simpler and cheaper to do over time. It uses aquarium bubble pumps to produce low pressure air and this air is used to airlift pump water that circulates to the plants in the garden  in an endless loop.   I measured a few days ago and my bubble pump is producing 22 inches water pressure (0.8 psi) at the pump and 60 litres per hour of air at this pressure and this drives all the pallet gardens at a great distance (100 ft ) from the pump. I use a 3.5 watt air pump. I would just  love it if it could be off grid, and driven by solar heat in a low tech way.    Anyone want to try to do this?  Because then it is of great value in poor countries.   Just to give you an idea of how little heat you need to make this pressure.  If you heat air from 20 degrees C to 36 degrees C  (68 F to 97 F)  in a closed container, you get 0.8 psi pressure increase in the container!  That is the bar, and it would be really hard to set it lower than that!    I do not yet understand stirling engines or fluidyne pumps but I think they could do this.  If I try it, I will have cylinders of air alternatively heating and cooling  in the sun and valved to pump the air in one direction.  But if you are clever, I am sure you can do better than that with fluidyne or flutterwing wind power. I would love to see some comments and interest in this.   It IS working and people are going to be very interested as gardening season gets into full swing.    Playlists are http://www.youtube.com/playlist?list=PL00C41C26C91A76BB&feature=view_all for the pallet gardening and http://www.youtube.com/playlist?list=PLkzXlmAwZTZcHUq4YX8__3qLEJIIzTduW&feature=view_all for some amazing alternative wind, water and solar machines. Thanks Brian

Topic by gaiatechnician 6 years ago


British Land Speed Recod Was a Breeze, Thrashes US Record.

On the morning of March 26th, on the dry Lake Ivanpah, The Ecotricity Greenbird driven by British engineer, Richard Jenkins smashed the world land speed record for wind powered vehicles. The Greenbird clocked 126.1 mph (202.9 km/h) , eclipsing the old, American held, record of 116 mph , set by Bob Schumacher in the Iron Duck in March 1999 at the same location.The fully-composite craft (the only metal is in some of the bearings) used a solid wing to reach speeds up to five times that of the actual wind.The wing also provides unwanted lift, so it uses the same downthrust technology as F1 cars - at speed, the 600kg car presses down on the salt-flats with a force of almost 10,000N.Greenbird website.

Topic by Kiteman 10 years ago  |  last reply 10 years ago


selfcontained electric car?

I had a few ideas on how to make more efficient cars. First off why is it we have NO generators being used while stuffs rotating. Take a small generator with a rubber drive point...like there a chain or belt would go... and place that on the tires. This is a friction driven generator which means that it would not work well in the rain. These...if done right... could keep the car running and then keep the battery charged. Using the battery only for stops. I also think we need to figure out a way to put a coil in the drive train somewhere. Making it to where when the car stops the coil is wound tight, when the car takes off again the coil could unwind and help the car take off. this feature added to gasoline engines would help cut the cost of gas greatly, not to mention emissions.

Topic by NativeSs 7 years ago  |  last reply 7 years ago


Saul Griffith awarded a MacArthur grant!

Saul Griffith from Squid Labs, Howtoons, Instructables, and other cool companies has been awarded the MacArthur "genius" grant. He gets $500k because he's so genius-y and it couldn't be going to a better guy. Saul Griffith is an inventor whose innovations span industrial design, technology, and science education. Through a variety of endeavors at MIT and as a principal in Squid Labs, Griffith demonstrates his boundless energy for inventing across diverse disciplines in the global public interest. While still a graduate student at MIT, he designed a unique membrane-based molding system that can produce a variety of common lenses from a single pair of flexible molding surfaces. This prototype has the potential to change the economics of corrective lenses in rural and underserved communities around the world and continues to be a major focus of research and development energy at Squid Labs. At MIT, Griffith co-founded Thinkcycle.org, a web community that has produced socially conscious engineering solutions, such as novel household water-treatment systems. Thinkcycle.org is the forerunner of Instructables.com, a remarkable do-it-yourself website driven by user contributions. He is also a creative force behind HowToons, an animated educational resource designed to engage children in hands-on science and engineering projects. Through the spin-off company Potenco, Griffith initiated the project design for a hand-held human-powered generator, which has the potential significantly to improve access to electronic devices such as laptops and water purifiers throughout the world. Though still quite young, he holds several patents in optics, textiles, and nanotechnology. In these engineering ventures as well as others yet to be imagined, Griffith is a prodigy of invention in service of the world community. Saul Griffith received a B.MET.E. (1997) from the University of New South Wales in Sydney, Australia, an M.E. (2000) from the University of Sydney, and an M.S. (2001) and Ph.D. (2004) from the Massachusetts Institute of Technology. He is a co-founding partner of Squid Labs and serves as a technical advisor at Potenco in Alameda, California. full story

Topic by fungus amungus 11 years ago  |  last reply 11 years ago


How do I construct a maser?

So I have mentioned before about my plans to build a HERF gun using a magnetron powered by a highspeed motor w/ permanent magnets that serves as a generator(it's driven by a minature gas turbine engine). But the issue of collimating the microwaves into a beam that can travel at least 4 miles without significant diffraction is an issue I'm still working on. Now magnetrons have an efficient of roughly 70%.  So here's the idea: The magnetron's output coupling loop(antenna) will be inserted into a highly tempered glass cylinder that is attached to the top of the magnetron and the cylinder will be filled with either hydrogen gas or (anhydrous)ammonia. The oscillating RF field will pump the gas molecules at their microwave region resonant frequencies(if I use ammonia that will mean I need the magnetron to produce peak power at 24 GHz)and stimulate microwave emission by the molecules(population inversion). Has this technique ever been demonstrated experimentally? I know that RF radiation can be used to heat up hydrogen gas into plasma but maybe there are some references to masers constructed in this fashion.

Question by YugZ0h0th 5 years ago  |  last reply 5 years ago


more powerful, portable amp

I was messing around with some op-amps, building variations of the CMoy amp, etc. But I became depressed quickly -- these ICs' data sheets say that at the safe maximum of 15 volts, they can only pump out around 1/4 watt of power on a single channel! Well, i have a full range driver that really needs more power to sound decent. I was wondering what the normal way of constructing an amp would be if I were looking for 5 to 10 watts of power. *edit*: i'm not looking to run this thing off of batteries... i'm sure at 10 watts, a couple of D cells would get drained rather quickly... I recently cracked open an old 4.1 computer sound system (by microlabs) and scrapped the 5 drivers (4 satellites and a 5 inch sub), two big 3700 uF caps, and two JRC4558D dual op-amp ICs from the amplifier. I read up on the JRC chip (actually, just the data sheet from the RC5448D, the texas instruments flavor, i guess the JRC is discontinued) and it seems that this thing only puts out a max of 200 mW per channel, and typically around 90 mW. Ok i know those speakers didn't get THAT loud without distortion, but i am CERTAIN it was more than 800 mW for those 4 satellites. I am a new computer engineering student, so i can understand the physics behind the electronics, but i am nowhere near the level to start reverse-engineering that amp board. So how did these speakers get driven so hard? THANKS for reading!!!!!

Topic by samurai1200 11 years ago  |  last reply 11 years ago


Estimating torque on microscope stage

Hello,I am involved in a project, based on the technologie used in microscope stages. https://www.ebay.com/itm/Olympus-Mechanical-Microscope-Stage-w-Specimen-Holder-From-Model-BH2/123699351875?hash=item1ccd0e5143:g:Hs4AAOSw0TpckTT2These have an X and Y axis which can move independently and are driven by rack and pinion gear, controlled by a translation unit with two knobs. The consistency of the grease used in the shafts that connect the knobs with the gear generates great damping and resistence when the stage is moved, so that the movement is nicely smooth and slow. I am not a technician/engineer but a designer and know nothing about torque. I need to know the torque that is generated by this sort of system, especially when the stage is moved BY HAND, so not using the knobs. I would be interested in the minimum and maximum torque that is generated when pushing the stage by hand.I am thinking of using a slip clutch/torque limiter to replace the translation unit, because I don't want to depend on grease. That is why I need to know the torque. Anyway, maybe somebody on this forum has a better idea. I'm all open.Thanks,Rob

Question by butterflies55555 7 weeks ago  |  last reply 7 weeks ago


Hoverbike takes off

Australian Christopher Malloy has built what seems to be a working hoverbike.  Built in his Sydney garage, with a custom carbon-fibre frame and a BMW engine, the machine is being touted as "Star Wars Speeder bike Mk1". Currently restricted to tethered flights of a few inches altitude, Malloy claims the bike feels stable, and is just waiting permission to undertake untethered tests. 'I am still ground testing at the moment only because I'm not 100 per cent sure what will happen so the straps are there to cover the unknown. I haven't had the pleasure of flying round the countryside yet. 'It is quite stable and doesn't want to tip over but if something unplanned happened during testing I wouldn't want to break the prototype. 'The Hoverbike was built with safety in mind so at least three components have to fail before you might have a serious airborne failure. 'There are also two explosive parachutes attached to the airframe and of course the rider could choose to wear their own parachute too. He predicts: 10,000ft altitude. 100mph 92 mile, 45 minute flight on one tank £45,000 pricetag The hoverbike should also have "ultralight" status - at only 270kg, under US regulations, no pilot's license would be required.  Since it has no driven wheels, it shouldn't require a road license either...!  Malloy is a former helicopter pilot, and says those skills are helpful when flying the hoverbike, but also says that the unique craft ultimately needs no more skill to fly than a motorbike, with speed and direction being controlled by a mixture of throttle and body-posture. As soon as I win the Lottery, I know who is going to get a knock at the door... Via Daily Mail

Topic by Kiteman 7 years ago  |  last reply 7 years ago


Research on DIY: Looking for Volunteers in- and around Amsterdam

Hi all, My name is Tal Amram, graduate student of Industrial Design at the Delft University of Engineering. For my graduation assignment I’m setting up a study about the potential benefits of ‘connected objects’ in an Internet of Things for creative processes of the Maker community. More specifically, I am aiming my study at ‘Home Improvement’, interpreted also as the making of furniture, lighting, home decoration or domotics.  For this study I am looking for volunteers in Amsterdam (or its proximity) to execute a small Home Improvement design assignment (for your own home) that takes a week, on which you will spend about 20-30 minutes per day. You eligible if you have experience with making things to improve your home environment and have worked with 3D-printers before. You will be provided by me with a package that contains a logbook with short assignments and some materials to use for simple prototypes or inspiration. This week starts on Monday, November 23rd and ends on Monday November 30th with a session in the Waag FabLab from 19:00 - 20:30. During this session, I will host a group discussion with all six participants during which we will share our experiences and discuss our separate processes. I will reserve the 3D-printer for (- and preceding) this session so as to make it possible to materialise your design. I would love to hear if you, or perhaps anyone you know, would be interested in participating in this study! Please contact me via my e-mail address as provided below. Feel free to contact me also in case you have any questions or remarks about this study or my project in general. t.amram@tudelft.nl Best Regards, Tal Amram

Topic by talamram 3 years ago


Record Solar Powered Flight

UK-built solar-powered plane has set an unofficial world endurance record for a flight by an unmanned aircraft.The Zephyr-6, as it is known, stayed aloft for more than three days, running through the night on batteries it had recharged in sunlight.The flight was a demonstration for the US military, which is looking for new types of technology to support its troops on the ground.Craft like Zephyr might make ideal platforms for reconnaissance.They could also be used to relay battlefield communications.Chris Kelleher, from UK defence and research firm QinetiQ, said Unmanned Aerial Vehicles (UAVs) offer advantages over traditional aircraft and even satellites."The principal advantage is persistence - that you would be there all the time," he told BBC News. "A satellite goes over the same part of the Earth twice a day - and one of those is at night - so it's only really getting a snapshot of activity. Zephyr would be watching all day." The latest flight was conducted at the US Army's Yuma Proving Ground in Arizona.The Zephyr flew non-stop for 82 hours, 37 minutes.That time beats the current official world record for unmanned flight set by the US robot plane Global Hawk - of 30 hours, 24 minutes - and even Zephyr's own previous best of 54 hours achieved last year.However, the Yuma mark remains "unofficial" because QinetiQ did not involve the FAI (Federation Aeronautique Internationale), the world air sports federation, which sanctions all record attempts.The US Department of Defense funded the demonstration flight under its Joint Capability Technology Demonstration (JCTD) programme. The 30kg Zephyr was guided by remote control to an operating altitude in excess of 18km (60,000ft), and then flown on autopilot and via satellite communication.It tested a communications payload weighing approximately 2kg.At first sight, the propeller-driven Zephyr looks to be just another model aircraft, and it is even launched by hand. But this "pilotless" vehicle with its 18-metre wingspan incorporates world-leading technologies.Its structure uses ultra-lightweight carbon-fibre material; and the plane flies on solar power generated by amorphous silicon solar arrays no thicker than sheets of paper. These are glued over the aircraft's wings.To get through the night, the propellers are powered from lithium-sulphur batteries which are topped up during the day."A lot of effort has gone into power storage and light-weighting the systems," explained Mr Kelleher. "Lithium sulphur is more than double the energy density of the best alternative technology which is lithium polymer batteries. The engineers from the Farnborough-based company are now collaborating with the American aerospace giant Boeing on a defence project codenamed Vulture.This would see the biggest plane in history take to the sky, powered by the sun and capable of carrying a 450-kilo (1,000lb) payload.US commanders say the design must be able to maintain its position over a particular spot on the Earth's surface uninterrupted for five years. QinetiQ is the public company that used to be the British Government's military research department, before they privatised it.BBC articleQinetiQ's page on Zephyr

Topic by Kiteman 10 years ago  |  last reply 10 years ago


Very Small Scale Power Generation in Developing World

Hello Everyone, I volunteer for a non-profit which distributes solar lanterns primarily to students as well as people who are in need of the lights.  Things have been going well but a lot of people have inquired about us providing access to a higher powered version for various reasons and we've noticed that some households go back to their old ways when the lanterns don't receive enough sun during the day.  Temporarily we are solving the problem by having local entrepreneurs charge batteries for the families for a small fee but we feel that this should not be a permanent solution. It's not the price that's the issue it's that sometimes the people have to walk for a number of kilometers to get to the nearest charging station or have to cross dangerous terrain (I have personally experienced this). Over the last 3 years we have helped over 5000 families by giving them solar lights so we would like to modify all those units to have more stable energy generation. Our current version has an output of 5 watts. We are looking to buy or build a unit which produces a maximum 8wh an hour until the fuel source runs out or something that can generate in a more slower rate such as 40wh in 16 hours so we can let it run overnight and have the power stored in a battery. We are primarily a donation driven group so something with low cost and maintenance would be really great.  We highly subsidize the price to a large percentage of the households but we also provide them free for the lowest 10% of households who can't even afford the lowered price. I personally think that something which can generate electricity from hydrocarbons due to their high energy density and easy access would be ideal but I'm not an engineer so what do I know.  I'm not sure if this helps in any way but a number of years ago we transitioned a large number of houses from wood fired stoves to gas and as all the families that we help actually have access to gas I was wondering if any good technology exists where electricity can be generated by gas that can meet the low cost and maintenance criteria.  I've looked into thermoelectric generators but they are really inefficient and people will be wasting money to heat their house in a country where average temperatures are in the 30'sC I also see a future issue regarding battery degradation as we use small lead acid batteries and while thinking of a way to solve this I came up with the following idea and is one of the reasons that I'm posting on instructables. What if a pedal powered flywheel generator was built with a 200W generating capacity and 40Wh worth of 'storage'.  When you pedal you will spin up the flywheel and it will store the energy until you need the electricity again and we could also wire up the solar panel that we already use to spin up the flywheel.  So when the sun is out the panel is used and on rainy days and during the night you pedal for a couple of minutes for one hour of lights.  If the flywheel can store the energy for a number of hours then someone could pedal for a couple of minutes at a time throughout the day and not have to do it at night. This is just an idea that I came up with and if anyone has any ideas I'll be really interested in knowing about it (obviously the above solution is not ideal because they have to put some work into generation but it's the best that I can do).  I've quite recently been looking into different types of fuel cells powered by m/ethanol and others like solid oxide cells and they seem interesting (does anyone here have any experience in building these type of cells?).  This community has a lot of intelligent members who think outside the box so I'm confident that we can come up with something. This ended up being a bit longer than expected and if you've read this far, thank you. I wasn't sure about what section to post this in, square peg is the one I chose out of 5 so if this is wrong please feel free to move it to the correct section. Help and advice will be very much appreciated. Kindest Regards

Topic by ragun8 5 years ago  |  last reply 5 years ago


The Memristor - they've found it!

This came out quite a few days ago, but I haven't seen it until today.HP's Henry Williams and his group have accidentally stumbled upon the fourth fundamental element in electronics - the memory resistor, or memristor. Basically, it's a resistor that changes its resistance with elapsed current flow, or total amount of charge that has passed through it, and retains its resistance even after current ceases to flow through it. From the article:"The classic analogy for a resistor is a pipe through which water (electricity) runs. The width of the pipe is analogous to the resistance of the flow of current—the narrower the pipe, the greater the resistance. Normal resistors have an unchanging pipe size. A memristor, on the other hand, changes with the amount of water that gets pushed through. If you push water through the pipe in one direction, the pipe gets larger (less resistive). If you push the water in the other direction, the pipe gets smaller (more resistive). And the memristor remembers. When the water flow is turned off, the pipe size does not change.Such a mechanism could technically be replicated using transistors and capacitors, but, Williams says, “it takes a lot of transistors and capacitors to do the job of a single memristor.”The memristor's memory has consequences: the reason computers have to be rebooted every time they are turned on is that their logic circuits are incapable of holding their bits after the power is shut off. But because a memristor can remember voltages, a memristor-driven computer would arguably never need a reboot. “You could leave all your Word files and spreadsheets open, turn off your computer, and go get a cup of coffee or go on vacation for two weeks,” says Williams. “When you come back, you turn on your computer and everything is instantly on the screen exactly the way you left it. "Apparently, evidence of memristors has been around for quite a while, but it was only until now, during the age of nano-technological exploration, that we finally have labeled the "strange voltages" we've found in experimental circuits as a result of memristor behavior. The discovery was made while doping Titanium dioxide with some dopant that the article fails to cover. Anyhow, the resistance of TiO2 changes with the amount of dopant covering it. Since the dopant does not adhere perfectly to the TiO2 substrate, the flow of charges (electrons) can move the dopant, and cause it to cover more or less of the substrate, thus changing its resistance. "Williams found an ideal memristor in titanium dioxide—the stuff of white paint and sunscreen. Like silicon, titanium dioxide (TiO2) is a semiconductor, and in its pure state it is highly resistive. However, it can be doped with other elements to make it very conductive. In TiO2, the dopants don't stay stationary in a high electric field; they tend to drift in the direction of the current. Such mobility is poison to a transistor, but it turns out that's exactly what makes a memristor work. Putting a bias voltage across a thin film of TiO2 semiconductor that has dopants only on one side causes them to move into the pure TiO2 on the other side and thus lowers the resistance. Running current in the other direction will then push the dopants back into place, increasing the TiO2's resistance.HP Labs is now working out how to manufacture memristors from TiO2 and other materials and figuring out the physics behind them. They also have a circuit group working out how to integrate memristors and silicon circuits on the same chip. The HP group has a hybrid silicon CMOS memristor chip “sitting on a chip tester in our lab right now,” says Williams."I think this is pretty awesome, considering the current breakthroughs in nanotechnology and downsizing of transistors, memristors would enable a whole new field to be born, and circuit theory may have to be re-designed.Like Leon Chua said, the man who first came up with the idea of a memristor, "now all the EE textbooks need to be changed."These next few years in the field of EE should be very interesting =)Image from Spectrum Online

Topic by T3h_Muffinator 11 years ago  |  last reply 11 years ago


The Dream Factory - Squid Labs and Instructables in Wired September 2005

This was Instructables' big debut. The author, Clive Thompson, came and hung out at Squid Labs for a couple of days, and later on we had a hilarious half-day photoshoot where the photographers couldn't remember Dan's name and had to keep calling him "wrench."Wired 13.09 The Dream Factoryby Clive ThompsonThey're already living that future in a small warehouse in Emeryville, California. It's the headquarters of Squid Labs, run by a gang of five MIT alums who by day create prototypes of new technologies for outside firms - and by night fabricate weird gizmos just for fun."Everything I own is basically one of a kind," says a cheery Saul Griffith, one of the cofounders, as he crouches on the floor of his dust-covered workshop, rooting through an enormous bucket of metal brackets and bolts. A tall, shaggy Australian, he's wearing ragged flip-flops and a pair of cargo pants so stained with oil and grime that I can't determine their original color. Dozens of his group's inventions lie scattered about: a Frisbee embedded with microchip-driven LEDs, a set of robots precision-cut from plastic, a bunch of helmet-mounted laser-and-GPS sensors designed to help firefighters locate one another in a blazing house.Today, Griffith is building a "hybrid electric bicycle" with a hidden battery compartment inside the bike's 4-foot-long, chopper-style front forks. To hold the forks in place, he spent the morning designing a bracket, then cut out a flat template for it on Squid Labs' laser cutter. Now, with that template as a guide, he hacks the shape out of quarter-inch steel, using a terrifyingly loud metal cutter. "I'm really into this 'tractor' aesthetic, getting everything to look like industrial machinery!" he hollers over the cutter's shrieks, while a 3-foot cone of orange sparks flies up and ricochets off his face.Every few minutes, Griffith pauses to snap a photo of his progress. When done, he'll write up a comprehensive guide on how to build his project. This, he argues, is the next crucial step in fab culture: getting hobbyists to carefully document their plans and share them online. Squid Labs is hoping to kick-start such sharing this fall when it launches Instructables.com - an open database of interesting projects and fab techniques, "kind of like a Wikipedia for making stuff," Griffith explains. If people want to build his electric hybrid chopper bicycle, they'll be able to download the CorelDraw design of the bracket and send it someplace like eMachineShop to have their own copy printed."We got inspired when we looked at all these guys who'd engineered these incredible, modded parts for their Harleys. They'd have amazing photos of them, but they'd never post the CAD image," Griffith says. "We were like, Why not go open source?"Later that day, I get a taste of how weirdly transformative this idea is. I'm hanging out with Dan Goldwater - another Squid Labs cofounder - and admiring one of his inventions. It's a pair of plastic gears that sit on a bike pedal and power a tiny generator. As you ride, you can run LED lights or a radio. I tell him I'd love to have a version of it myself. So a couple of Squid Labs guys go over to the laser cutter, pull up the design, and a few minutes later hand me exact copies of Goldwater's gears. Design once, print often. "Pretty cool, eh?" Goldwater grins."Griffith imagines that fab tools could produce new economic models for creators. Suppose a hobbyist made a cool plastic exterior for an MP3 player. Suppose she put the design online, and 700 people downloaded the file and had it printed at eMachineShop. "At what point," he asks, "would a manufacturer say, Hey, there's a market here - and offer to buy the design from her?""So, sure, soon we'll be able to build anything. But should we? "Let's say everyone suddenly can make their own hood ornaments. What if they actually do that? The real world would look like the Internet in 1996, when people started making their own Web sites." Griffith shudders. "Remember those hideous-looking psychedelic backgrounds and stupid animations? And blinking tags?""Rainbow dividers," Goldwater adds.It's a good point - and it makes me anxious about my guitar. Sure, it looked fine onscreen. But what if it turns out to be a monstrosity in my hands? Recalling my decision to use clear acrylic for the body, I break into a nervous sweat. It's going to look like something from a mid-'80s, big-hair heavy-metal band! What the hell was I thinking?Griffith interrupts my panic to announce that his chopper is ready. He wheels it onto the street, all five Squid Labbers in tow. Eric Wilhelm, a lanky designer, offers to be the test pilot. He straps on a helmet and mounts the seat. "Does it have brakes?" he asks."Sort of," Griffith says."It's amazing how often brakes are an afterthought," Wilhelm sighs. Then he hits the electric starter and peels off.

Topic by ewilhelm 10 years ago


Technology Makes Cheap Drinking Water from Air

INTRODUCTION:   How can we best apply basic technology to help the underprivileged and/or disaster-hit countries like Haiti? Daily hygiene and nourishment are among the top needs for disaster ridden regions!  Simply put, no water means no hygiene. The Romans understood that over two millennia ago and created their complexly beautiful aqueduct networks for handling both fresh and wastewater! Other ingenious water systems like “air wells” have been found in the city of Theodosia (cf: discovered in 1900 by Zibold, see Zibold’s Collectors/Dehumidifiers) dating back to Greco-Roman times during the Byzantine Empire. These were strictly passive systems that naturally dehumidified air, collecting its potable water in underground basins. All air, even in relatively dry desert regions, will precipitate or release its natural water content (initially in the form of vapor) through condensation when it hits its dew-point temperature and below. That means you “chill” it to an appropriate level that is anywhere from 5F to 50F below its current air temperature, depending upon how much water content (relative humidity) it has locally absorbed. The condensation of the water vapor releases its internal latent heat (reheating the cooled air) which must be constantly dissipated (absorbed by something) in order for water formation to steadily continue. So how do we dissipate this resultant vapor-heat and chill our air without any infrastructure or electricity, in an underprivileged or disaster-ridden region? We simply bury a long cast-iron or any metallic drain-pipe sufficiently underground where the temperature of the earth is naturally held to a constant at around 45F to 55F. That’s our “free” chiller gift from nature. One end of the pipe, Figure-1,  sticks out of the ground to suck-in local outside hot air, and the other end dumps cooled dry air and water into an underground cistern where it gets collected and is piped to the surface to both exhaust the cooled dry air and connect to a water pump. We need a hand operated water pump to lift up the water above ground, and we need an electric fan to constantly pump air through the ground-chilled piping system. We can even force the cooled piped air to exhaust into a tent-like structure where it provides air conditioning as an added bonus, but this adds the penalty of both power and the increased fan size necessary to drive our required airflow further into an enclosure! While this concept is not “passive” (requiring electricity to work) like those clever Byzantine air-wells, it will produce much more potable water and within a smaller volume than those elegantly passive historic devices. The electricity for our fan power requirements can be produced by any one of four ways using either “active” or “passive” techniques: 1) An active playground or bike-pedaling-person or oxen-driven mechanism-generator, 2) A passive windmill generator, 3) A passive solar energy collection system that directly generates electricity, or 4) A passive thermo-electric system that directly generates electricity using the Peltier effect, operating solely on temperature differences between the cell’s top and bottom surface (we jury-rig the cool pipe and hot ambient air to contact separate sides of the cell). Depending upon how much water is needed, the required air volume plus pipe length and diameter, together with the fan will be sized accordingly. We can also configure groups of parallel fan-driven air pipes that are radially fed into the cistern. The sizing of this underground network depends upon the ambient air’s local average temperature and relative humidity (how much water gets absorbed into the air) plus buried pipe depth and effective underground temperatures achieved. The basic concept is one where we “wring” water from air at some given humidity content. The higher its relative humidity the more water is recovered from the air. The air-wringing process simply chills the air as it scrubs along the cooled internal pipe surface until it starts to rain inside the pipe from condensation onto its surface. The condensation is like the dew that forms on car windows, grass or any cooled surface in the early morning, before the sun comes out and evaporates the dew back into the heating air. A further bonus is that our dew-formed water is naturally distilled and very clean. It is potable water ready to drink without the need for additional sterilizing agents. Of course, we must make sure that the interior piping and cistern network is biologically cleansed before burying it underground. The hand pump with its 10 to 15 foot extended piping to reach the underground cistern must also be cleansed. The beauty of this constantly replenishable water supply is its convenient underground installation anywhere! After the in-ground installation, we have a virtual, partially passive, no moving parts, non-breakdown system containing above ground total access to all moving parts that could breakdown, namely the water pump and electric fan. Also, it is easily maintained, with few moving parts (water hand-pump and electric fan) and basically lacking any technical complexity which makes it ideal for technologically backward regions. The example below uses a relatively small industrial fan moving air at 1500 CFM (Cubic Feet per Minute) with a DC motor rated at 1kW. This fan together with our underground piping system will conservatively generate 12 GPH (Gallons Per Hour) of potable drinking water without need for any purification chemistry. Based on an average electrical cost of 14-cents per kWh (kilo-Watt hour), the typical commercial distillation of one gallon of drinking water costs roughly 35-cents as compared to our cost of only 1.2-cents. Furthermore, if we decide to go green and use solar energy for generating our water, it would effectively cost us nothing beyond the initial installation! USING A PSYCHROMETRIC CHART TO SIZE OUR WATER SUPPLY: The following gets a little technical and is only provided for those die-hards who are truly interested in how the science works. Those non-technically schooled may skip this part and not miss the basic concept. Figure-2 shows a Psychrometric Chart for air. This chart summarizes some of the basic thermodynamic properties of air throughout its typical range of operating temperature. The chart uses six basic air properties that defines the physical chemistry of water evaporation into air:  (1) the enthalpy or total energy contained within a unit of air which is a combination of its internal and external energy, expressed as the amount of BTU-energy per unit mass of reference dry-air, (2) the specific volume or the ratio of a unit volume of local air to its mass of reference dry-air, (3) the humidity ratio or the amount (mass) of moisture in a local unit of air divided by its reference mass of dry-air, (4) the percent relative humidity per unit of local air, or the mass ratio (expressed in percentage form) of the partial pressure of water vapor in the air-water mixture to the saturated vapor pressure of water at those conditions (the relative humidity depends not only on air temperature but also on the pressure of the system of interest),  (5) the dry-bulb temperature or the locally measured air temperature, and (6) the wet-bulb temperature or saturation temperature which is the local air temperature experienced during constant water evaporation (a wet-bulb thermometer is typically used:   a thermometer that measures resultant temperature while wrapped in a water wet-gauze and spun to generate local air movement and max-evaporation)  1.0   The Process and A Sample Calculation Our Psychrometric Chart uses six thermodynamic properties that help to determine the amount of water available for extraction from the local ambient air as a function of its temperature, pressure and relative humidity.  Let’s assume the following local ambient conditions for the region we plan to construct our water system at:  (1) Typical daily air temperature Td = 106F and one atmosphere pressure assumed at sea-level, (2) Relative Humidity, RH = 55%, and (3) Typical underground temperature down at six feet is measured at Tu=55F (at 12ft. it drops to ~45F). This yields the following calculated results for obtaining a steady-state supply (changes at night) of water to fill the cistern:      1)      In our example, the “local” air (dry-bulb) temperature is Td=106F, at a relative humidity of RH= 55%.  Fig-2 indicates that the resultant Humidity Ratio is HR= 0.0253 Lbs-water/Lb-Dry-Air (intersection of Td=106F line and RH=55% line, then horizontal to HR value).  We then determine the “gulp” of air volume containing the HR Lbs-water which corresponds to the point of intersection of Td and RH. Interpolating on specific volume “mv” yields mv=14.7 ft3/Lb-Dry-Air (this value sets the optimum unit airflow for our given ambient conditions, and creates a ballpark pipe length to diameter ratio needed later). It represents the basic unit of air volume that will enter our underground pipe per given time, and ultimately defines the size of our fan and piping network. For increased water creation, multiples of this unit volume will scale up the additional amounts of water that can be collected. 2)      As the inlet air cools down to a temperature of Tu=55F, from contact with the relatively cold underground pipe, we follow the constant enthalpy line (red upward left-diagonal) from the intersection of Td and RH to its saturated air temperature condition of Ts= ~88F, which is its dew-point temperature where the corresponding local RH=100%.  At this temperature or under, the air precipitates and releases its moisture content, resulting in water condensation onto the pipe walls.  Since our air will chill to a final pipe temperature of Tu=~55F, we follow the RH=100% saturated curve (green) down to yield an HR=~0.009 Lbs-water/Lb-Dry-Air. This is how much water is left in the air when it gets to 55F.  Therefore for every pound of local outside air that enters the pipe, mw=0.0253 – 0.009 = 0.0163 pounds of absolute pure, distilled potable water precipitates onto the inside pipe wall (per pound of dry air that is cooled and dehydrated) to gravity-flow out the pipe exit and into the cistern. 3)      We now convert pounds of air per unit time into a unitized volumetric airflow that yields gallons of hygienically pure potable water production per unit time. For every Va=100 ft3 of local volumetric air movement per minute (CFM) through the pipe, which translates into ma=Va/mv= 100/14.7 = 6.8 lbs. of dry air per minute or 6.8 * 60 = 408 lbs. per hour (PPH), to yield a water-flow of mwf=ma * mw = 408 * 0.0163 = 6.65 PPH or 6.65/8.345 = 0.8 GPH of water.  An industrial fan rated at 1kW DC will typically move 1500 CFM at a pressure of 8-iwc, to continuously produce 15 * 0.8 = 12 GPH of pristine potable water. 4)      Not shown here are the design details of sizing our pipe, fan and solar collection system for electric power requirements using heat transfer principles coupled with a thermodynamic heat balance, and aerodynamic fan performance assessment. These details help to size the electric power generation requirements plus margin used to properly size a solar collector containing further margins for overcast days. The engineering involved here is straight forward but beyond the scope of the current project.

Topic by RT-101 7 years ago  |  last reply 1 year ago


8 Reasons you'll rejoice when we hit $8 a gallon gasoline

This article in MarketWatch written by Chris Pummer mostly matches my opinions. My favorite is #2Here is the text:SAN FRANCISCO (MarketWatch) -- For one of the nastiest substances on earth, crude oil has an amazing grip on the globe. We all know the stuff's poison, yet we're as dependent on it as our air and water supplies -- which, of course, is what oil is poisoning.Shouldn't we be technologically advanced enough here in the 21st Century to quit siphoning off the pus of the Earth? Regardless whether you believe global warming is threatening the planet's future, you must admit crude is passé. Americans should be celebrating rather than shuddering over the arrival of $4-a-gallon gasoline. We lived on cheap gas too long, failed to innovate and now face the consequences of competing for a finite resource amid fast-expanding global demand.A further price rise as in Europe to $8 a gallon -- or $200 and more to fill a large SUV's tank -- would be a catalyst for economic, political and social change of profound national and global impact. We could face an economic squeeze, but it would be the pain before the gain.The U.S. economy absorbed a tripling in gas prices in the last six years without falling into recession, at least through March. Ravenous demand from China and India could see prices further double in the next few years -- and jumpstart the overdue process of weaning ourselves off fossil fuels.Consider the world of good that would come of pricing crude oil and gasoline at levels that would strain our finances as much as they're straining international relations and the planet's long-term health: 1. RIP for the internal-combustion engineThey may contain computer chips, but the power source for today's cars is little different than that which drove the first Model T 100 years ago. That we're still harnessed to this antiquated technology is testament to Big Oil's influence in Washington and success in squelching advances in fuel efficiency and alternative energy.Given our achievement in getting a giant mainframe's computing power into a handheld device in just a few decades, we should be able to do likewise with these dirty, little rolling power plants that served us well but are overdue for the scrap heap of history.2. Economic stimulusNecessity being the mother of invention, $8 gas would trigger all manner of investment sure to lead to groundbreaking advances. Job creation wouldn't be limited to research labs; it would rapidly spill over into lucrative manufacturing jobs that could help restore America's industrial base and make us a world leader in a critical realm.The most groundbreaking discoveries might still be 25 or more years off, but we won't see massive public and corporate funding of research initiatives until escalating oil costs threaten our national security and global stability -- a time that's fast approaching. 3. Wither the Middle East's cloutThis region that's contributed little to modern civilization exercises inordinate sway over the world because of its one significant contribution -- crude extraction. Aside from ensuring Israel's security, the U.S. would have virtually no strategic or business interest in this volatile, desolate region were it not for oil -- and its radical element wouldn't be able to demonize us as the exploiters of its people.In the near term, breaking our dependence on Middle Eastern oil may well require the acceptance of drilling in the Alaskan wilderness -- with the understanding that costly environmental protections could easily be built into the price of $8 gas. 4. Deflating oil potentatesOn a similar note, Venezuela's Hugo Chavez and Iran's Mahmoud Ahmadinejad recently gained a platform on the world stage because of their nations' sudden oil wealth. Without it, they would face the difficult task of building fair and just economies and societies on some other basis.How far would their message resonate -- and how long would they even stay in power -- if they were unable to buy off the temporary allegiance of their people with vast oil revenues? 5. Mass-transit developmentAnyone accustomed to taking mass transit to work knows the joy of a car-free commute. Yet there have been few major additions or improvements to our mass-transit systems in the last 30 years because cheap gas kept us in our cars. Confronted with $8 gas, millions of Americans would board buses, trains, ferries and bicycles and minimize the pollution, congestion and anxiety spawned by rush-hour traffic jams. More convenient routes and scheduling would accomplish that.6. An antidote to sprawlThe recent housing boom sparked further development of antiseptic, strip-mall communities in distant outlying areas. Making 100-mile-plus roundtrip commutes costlier will spur construction of more space-efficient housing closer to city centers, including cluster developments to accommodate the millions of baby boomers who will no longer need their big empty-nest suburban homes.Sure, there's plenty of land left to develop across our fruited plains, but building more housing around city and town centers will enhance the sense of community lacking in cookie-cutter developments slapped up in the hinterlands. 7. Restoration of financial disciplineFar too many Americans live beyond their means and nowhere is that more apparent than with our car payments. Enabled by eager lenders, many middle-income families carry two monthly payments of $400 or more on $20,000-plus vehicles that consume upwards of $15,000 of their annual take-home pay factoring in insurance, maintenance and gas.The sting of forking over $100 per fill-up would force all of us to look hard at how much of our precious income we blow on a transport vehicle that sits idle most of the time, and spur demand for the less-costly and more fuel-efficient small sedans and hatchbacks that Europeans have been driving for decades. 8. Easing global tensionsUnfortunately, we human beings aren't so far evolved that we won't resort to annihilating each other over energy resources. The existence of weapons of mass destruction aside, the present Iraq War could be the first of many sparked by competition for oil supplies.Steep prices will not only chill demand in the U.S., they will more importantly slow China and India's headlong rush to make the same mistakes we did in rapidly industrializing -- like selling $2,500 Tata cars to countless millions of Indians with little concern for the environmental consequences. If we succeed in developing viable energy alternatives, they could be a key export in helping us improve our balance of trade with consumer-goods producers. Additional considerationsWeaning ourselves off crude will hopefully be the crowning achievement that marks the progress of humankind in the 21st Century. With it may come development of oil-free products to replace the chemicals, pharmaceuticals, plastics, fertilizers and pesticides that now consume 16% of the world's crude-oil output and are likely culprits in fast-rising cancer rates.By its very definition, oil is crude. It's time we develop more refined energy sources and that will not happen without a cost-driven shift in demand.

Topic by Keith-Kid 10 years ago  |  last reply 10 years ago