confetti blower clogging

Hello everyone. I have a question which I think will be a simple one for you guys. I bought these mini confetti blowers for our church. They suck confetti, which are mainly small shiny rectangular pieces or some rose shaped paper-like material pieces, and blow them to the air. So ours came with a hose setup to suck the confetti: I decided to modify it to suck confetti from inside a box like these ones do: Here's a sketch of how it looks now with the box I made. What's happening though, the confetti pieces after few seconds form a clog where the box connects with the tube. If I push that clog with my hand, the confetti is sucked in and flows through the tubes and is blown just fine. I modified my box from the inside like so, but it didn't change anything. -> Someone unlike me who actually understands why that is happening, can you explain why clog happens and how would you suggest me to modify my box shape to fix this? Not that the hose setup is bad, it just looks like a modified vacuum cleaner like that and not very pretty to have in ceremonies and we still need a box to put the confetti pieces and the hose in to suck the confetti so I thought I could just have the box on the machine itself and make it easier to handle.

Posted by MarkL9 3 years ago

Principles of aerodynamics

The forces and counter forces of flight

Posted by SoDDiggerCpl 11 years ago

Green car mod roundup

Treehugger has a nice roundup of mods that people have made to their cars to make them more efficient or run on alternative fuels. They even included the Honda Accord that runs on trash in the list, which is pretty cool. Other mods include wood-burning cars, biodiesels, wood-burners, solar-power, hydrogen, and aerodynamic enhancements. Check out the link for the slideshow. Note: there are 17 slides, not 17 cars. 17 DIY Cars Hacked for Fuel Efficiency

Posted by fungus amungus 8 years ago

Zero to 300mph in 30 seconds. On two wheels.

Meet the world's fastest ever road vehicle built to reach an astonishing top speed of 340mph.The Acabion GTBO uses jet fighter technology and aerodynamics to reach its extraordinary speed propelled by a state-of-the-art turbo-charged engine.Its designers revealed it could reach 300mph in a blistering 30 seconds - substantially quicker than the rival Bugatti Veyron which takes 55 seconds to reach its top speed of 250mph.Good grief, that would rattle your teeth!The article implies that an electric version is in the pipeline as well.Daily Mail story750 hp and 700 lbs vehicle weight result in more than 2100 hp per ton. They boost the jet-like GTBO to jet-fighter punch and to new dimensions of both efficiency and speed.V-max 340 mph at half throttle, governor limited.0 to 300 mph in less than 30 sec.Economic theories tell us, that you can not maximize effect and minimize effort at the same time. The Acabion GTBO proves the opposite. It minimizes weight and maximizes power and aerodynamic efficiency. The effects are just out of this world.100 mph at 1.7% throttle and 100 miles per gallon.150 mph at 4.3% throttle and 62 miles per gallon.250 mph at 17% throttle and 25 miles per gallon.Acabion websiteMore photos at Jalopnik

Posted by Kiteman 10 years ago

alternatives to fiberglass

Hey guys im building an enclosed recumbent motorcycle and i am a bit stuck. im making the outer skin. to get a working aerodynamic shape, complex curves and all i want to use some flexible sheet which i can connect to the strong points of the motorcycle. i am thinking of using that polypropilene chicken wire, and i wonder if it would be good enough to be the base of the fairing and put fibreglass on top. my brother wants to use cedar strips as a base and cardboard strips mounted over them and fibreglass the resultant mess. then bondo the lot. any ideas. i am not describing this very well. a single sheet of a flexible matting will save me the trouble of making a mould of the fairing. thanks guys.

Posted by maninamousesuit 7 years ago

Looking For Game Show Contestants

DISCOVERY SCIENCE NOW CASTING A NEW GAME SHOW!!! The producers are looking for builders, scientist, inventors, engineers, carpenters, welders, mechanics, architects... who love to invent new gadgets; build robots; racing power tools; weld together bizarre machines that drive, fly, climb, shoot flames or launch projectiles... for a team challenge that will show off your handy skills such as: welding, knowledge of aeronautics, auto mechanics, hydraulics, carpentry, pyrotechnics, thermodynamics, aerodynamics, material science, electronics... If you, or someone you know, is a gonzo engineer/scientist or just a high-energy, creative, fun, builder Then email, your name and contact information to: This Game Show is for thinkers, dreamers and doers, who are eager to let their inner Mac Gyvers be seen, and are ready to collaborate with a team of other builders to beat the clock in order to "SAVE" the BIG PRIZE!!

Posted by demolition399 9 years ago

after school program help

I am hopefully going to be designing an after school program for the spring semester. the age group is potentially 5- 11. but could be, if i so choose, only 9-11. I am trying to create a program that is exciting, fun, educational and of course, relatively cheap. The first idea i have is to build a model wind tunnel, then have the students design and build pinewood racers (with assistance of course), then we can test the drag in the wind tunnel and make adjustments, then race them. Giving the students the oppertunity to learn a little about wood working and also aerodynamics. I am also looking for suggestions for other projects that would meet the criteria of fun, educational and inexpensive. so if anyone has any ideas at all please feel free to share them. also if anyone is intereted in persuing the above project i am happy to supply links, as they are all ideas i have stolen. thank you Alec

Posted by alec868 10 years ago

My First Semester Drawings

Hello!            Every school semester there is some downtime when I just draw cars. I don't have my normal critics this year because I am at college now so I figured I would see what the instructable community thinks of my cars. If you like aerodynamics and fast looking cars you should like my style. Also as you can tell I made up a car company to put all my cars under called Veloci. If I do have that car company in the future that's what it would be called. Anyway more to the point let me know what you like or don't like about any of these and I will try making a better batch this semester! Thanks! JonnyBGood [Please note not all of these cars are finished drawings! Some I just ran out of the inspirational drive to finish them.]

Posted by JonnyBGood 5 years ago


I have stumbled across this website years ago, and always found lots of fascinating projects here Since then ive also noticed that while its a community and people love to collaborate here, the design and layout of the website doesn't seem to lend itself so well to the task of collaborative projects we really are not making the best of the brain power that's here, wouldn't  it be great if people could search for projects to get involved in,, and published projects could list people and skills needed to make it happen. for example if i want to design a low cost wind turbine, to help bring power to remote places, im looking for engineers, aerodynamic specialists. and 3d designers to help develop it. Can we have a way to help these people to find each other?  and then an area where work can be set out and people can jump in and fill in the blanks. With the way the world and consumption of its resources is going, websites like this one, and the power the internet gives us to put our heads and efforts together to solve common problems is going to be vital Thoughts?

Posted by alexfno 6 years ago

Selling Nerf Stefans (Darts)

Honestly I have just found out that instructables has a market place! Sorry for posting this as an instructable! Anyway I just copied all of this from my instructable: Hey Guys! I'm selling nerf Stefans (darts) for very cheap! Every Item is FREE SHIPPING (to the USA)! The prices are: $8 for 25, $14.50 for 50, $19 for 75, $23 for 100. If you live out of the USA pm me and we can negotiate a shipping cost. Also, if you want more than 100 bullets pm me. Buy it at Thanks to TCBM on YT for the clip of it in action. EDIT: I changed the tip of the darts!!! Now they're more aerodynamic thanks to the dome of hot glue! Here's a picture of what they look like now:  I only except paypal right now, also please just buy them at the website i mentioned don't ask to pay with cash or something... ALSO I sell modified Nerf Guns just like Twisted, although I don't paint them...

Posted by Pizzapie500 8 years ago


Alright, well here's the gun I was talking about in my other thread. I'm doing pretty good, I actually got you guys a thread out the day after making the weapon. The name? It stands for TheDunkis' Bad A** Gun. Obviously, it doesn't mean worth crud. I just made it work out so it'd have the acronym TBAG =P.  It's a rather basic weapon. It ties with the BAW for my favorite weapon based around simplicity. I decided to scrap the removable magazine idea and just make it breach load. You can chamber a round directly so you can fire it like a single shot or you can continue to force rounds in to load the magazine. It has a charging "handle" in the side of the stock. And then of course I have the optional sight that I made and never wanted to take apart. Y'know how hard it was getting the little suckers to bend into the connectors like that? The main feature of this gun though is its ability to fire multiple rounds of a new ammo I've been experimenting with. They're not made of K'nex. Rather, they're pen ink cartridges from those bigger, more expensive kind that I can't remember the name of. They're almost the exact same diameter as K'nex rods. They're rather lightweight but, like oodammo, the majority of the weight is focused on the front. It's also somewhat pointy so it's just a tad more aerodynamic and fun to shoot into objects =P. They're very accurate and stable without the use of fins or anything so they get decent range. Obviously I wouldn't fire them at a living thing but it did give me the idea of using some sort of foam armor or something so that you could keep track of hits and such. Anyways, I like the feel of it. It's rather balanced and compact enough without being awkward to handle. I'm probably going to tape the handle. Expect a video tomorrow. I'm not sure when I'll post but might do it this weekend if I have the time.

Posted by TheDunkis 8 years ago

Guess My Mileage Contest!

In about two weeks, I will be embarking on a nearly 2000 mile road trip from the "right" coast to the "left" coast of the United States. I will send the person that guesses my fuel economy over the entire trip a $10 (USD) bill and 1 instructables patch.Rules1. Thou Shall Not Exceed My Mileage2. Thou Shall Guess a Number Ending in the Thousandths ( Thou Shall not guess a previously guessed number4. Thou Shall guess MPG (please no l/100km et. al. - just to keep the rules more simple)a. If no one guesses exactly, the guess closest, but not exceeding the real number wins.b. If two people guess the same number - see rule 3. The first person's guess is validc. You can change your guess by replying to your original guess - once your guess is changed, it can be taken by someone else.d. Guesses that do not accurate to the thousandth will be ignoredHere's some clues to assist your guessing.Car2000 Volkswagen Jetta2.0L Naturally Aspirated Gasoline Engine ~110hp ratedCurrently 102,xxx Miles on the Odometer5 Speed Manual GearboxOil change ~1500 miles ago (it will not be changed for another 9-10K miles)Tires inflated to 50/55 HOT - these are all seasonsGrille Blocked OffPassenger Mirror Folded in (possibly will be removed)Scanguage2 to monitor coolant temperature, trip mpg, TPS etc.CargoPossibly 1 mini fridge >100lbsMe: ~130lbsPassenger ~150lbsTwo suitcases (one will not exceed 50lbs)Possibly a third suitcase (not exceeding 50lbs)Lets tack on an additional 200lbs for things I'm not seeing nowEPA Estimates24mpg City31mpg Highway27mpg CombinedMeI use hypermile driving techniques... That is:1. Accelerate based on Brake Mean Fuel Consumption Charts (~2500-3000 RPM - 50% throttle = most efficiency)2. Coast and Burn with 3+++:1 coast-burn ratio (engine either off or idle)3. Engine Off at stoplights and approach4. Windows UP - AC OFF (this may change, but that's currently how I'm riding | AC will trump windows)5. I will not exceed the speed limit - I may travel below for optimal fuel economy6. Bump Start where applicable (following the same method the Prius uses to start its ICE)RouteCurrently being discussed and looked over. I20 is looking promising, but it's up in the air.GaslogPlease take this with a grain of salt. I only just recently started hypermiling (beginning of April lets say). So only the last tank (which was 100% city) reflects that.My GaslogCalculationCalculation will be based off the sum of the miles (accurate to the tenth) divided by the sum of the fuel pumped (accurate to the thousandth). Everything will be based on receipt, not scangauge2 data.ChangesThis is the section that I post changes to my car, cargo etc.. A change can be as basic as a bit more anticipated weight or as drastic as major aerodynamic modification or mechanical. A possible change may be a hot air intake.Finally, a note about my oil changes.... I send an oil sample to Blackstone Labs for oil analysis. My last oil change interval was a tad over 10K miles -- and the lab report indicated my oil was still good - everything was good except a slightly high Cu level. Not in the danger zone, but something to watch. My point is... Don't give me any crap about 3K miles - I like my oil films established and don't need constant oil changes screwing that up -- that's why I pay for oil analysis (besides, it comes out cheaper in the end anyway).

Posted by trebuchet03 11 years ago

"Knex War?" (The Math Bit)

Hey guy! Sharir1701 here and I just want to start off by saying that I'm not back into Knex warfare, but I have something to show you. About a year and a half ago, I posted this forum topic. There I explained why, in my opinion, just adding more rubber bands to a gun will not actually produce an overall better gun (past a certain, low point). I'm not getting back into that discussion, but I simply wanted to share something regarding that. Don't ask me how or why (I don't know, myself), but a few days ago I suddenly remembered that old assumption I made. Being a perfectionist, I hate leaving things unfinished or unexplained (particularly math and physics related inquiries). Back when I posted that topic, I had little to no formal Physics knowledge, and the beginnings of an understanding in mathematics. Now, I have a much broader understanding, much more knowledge, and an ability to explain and evaluate what I once couldn't. Anyway, what I'm trying to say is, back then, I didn't have the tools to prove my claims. I firmly believed in them, but I couldn't confirm them. It's nothing complicated, but, like I said, just something I'd like to share. I also want to point out that, although I personally don't enjoy spending days upon days perfecting a little plastic mechanism for firing (mostly) non-aerodynamic plastic projectiles, anymore, there still is a warm spot in my heart for the craft I once loved. More to the point - this is a small article just showing something I did in a few minutes the other day, that helps me to better understand how a Knex gun works. I hope that in writing this, more people that are still building guns, will think about more accurately calculating certain things about their guns to help improve their performance and hopefully produce more efficient guns. The final note I have is that I'm about to show you equations, all of which can be plugged with real, measurable numbers, to calculate to a high degree of accuracy, the forces at play. This means you can actually calculate the most efficient layout for a gun, and also that in designing your next, you will be able to use these equations, and many others, to find optimal solutions to your problems. So, what's all this fuss about? Well, basically, I just proved with a few, painfully easy equations that my conjecture about the forces in a gun, working on the pin, is true. I'll just get to it: First, Hooke's Law states that the force necessary to change the length of a spring or a (tense) rubber band is F=K*dX, where F is the force, dX is the distance you want to change, and K is a constant number, that each rubber band (or spring) has. You can quite easily measure both of these. For rubber bands connected parallel to each other (assuming they are the same type of rubber band, which ever is your chosen standard), this equation becomes F=K*dX*N, where N is the number of rubber bands used. dX and K are both constant in the regards of the pull of a pin on a standard Knex pin gun. Therefor, the amount of force required to cock a pin (pull it back to it's full length) is linearly correlated to the number of bands you put on your gun. Next, if we examine Newton's equation of work and energy, W=dE=F*dX, where W is the work, dE is the change in energy in your system (input from an external force, i.e. your hand), F is the force applied along a length of movement, and dX is that length. Let us define the base position of the pin (not cocked, minimum tension on the rubber bands, fully in the barrel, etc.) as having 0 energy. This then means that the work applied to the pin by cocking it is equal to all the potential energy it has. From this, plugging in the force, we get Ep=K*(dX)^2*N. Let us assume a perfect world, where we neglect the effects of friction and air resistance, and assume all the momentum of the pin is transferred into the bullet as it fires (I will briefly mention in the end, why everything we're neglecting here just strengthens my claim in reality, but let's continue for now). After being released (in other words, shot), the maximum velocity the pin reaches right before the end of it's journey can be found using the equation for kinetic energy Ek=1/2*M*(Vmax)^2, using the fact that (again, neglecting energy wasted as heat due to friction) the energy is conserved, as no external force is working on the system, which then means that Ep,start=Ek,end => K*(dX)^2*N=1/2*M*(Vmax)^2 => Vmax = sqrt(2*K*(dX)^2/M) * sqrt(N). The first sqrt term in the final equation is all one big constant (again, K is the ratio associated with the rubber band, dX is the distance the pin travels, and M is the mass of the pin), meaning we can conclude that (C for constant) Vmax=C*sqrt(N). Finally, force applied by a moving, massive object can be calculated using Newton's second law, F=dP/dT (P is the pin's momentum, T is the time it takes for the pin to go from velocity Vmax to 0, transferring all it's energy into the gun and the bullet, but as I said, let us assume all of it goes into the bullet), or F=M*dV/dT (M, mass of the pin, dV is the difference in velocity, Vmax-0, which is simply Vmax. This is because P=M*V, which means dP=M*dV, ignoring relativity). So, F=M*C/dT*sqrt(N). The time varies slightly, but insignificantly, so let us assume it is a constant. So that's it. The force exerted by the pin on the bullet is some constant (calculatable, as mentioned and as shown), times the sqrt of N, the number of rubber bands on the gun. So there you go. Just a little something I did out of the blue the other day and thought I would share a proof of my conjecture from what feels like eons ago. I hope you enjoyed. Finally, I would like to tell you guys, perhaps as a little tease, since I'm not sure if I will ever upload it, but I have made 1 more gun after I stopped posting. I have already slightly teased about it in my user info. I guess I'll tell you guys what it is if I'm already posting something here again :) Possibly my most enjoyable, most well received, and quite innovative gun of all time? The REMPAR-2. I built the REMPAR-3 (I was also going to call it S5 when I thought about posting it). In a brief summary, it's a pump action, chambering (or bolt action as I and many others falsely used to call it), magazine fed rifle, that's only 5 layers thick all over, except one tiny area where it's 8 layers thick (1.5 extra on either side), as a reinforcement, not necessary if you use less rubber bands. Oh, actually, there's another small necessary area where it's 7 layers thick, but it's tiny and doesn't make the gun look bulky at all, and who cares. Plus, the one is around the pump, which looks quite natural, and the other is "disguised" as a detachable sight (not really detachable) that also looks fine. It also looked fairly good for a gun that I made, it used (if I remember correctly) a grand total of 0 broken pieces, which is a big accomplishment for me (the mag has some broken white rods, but fuck off), and it worked flawlessly, reaching ranges over 80ft and being able to go at 2-4 rounds per second, depending on your skill level with it. In other words, I could shoot 4rps; My girlfriend, with no experience or practice, could do 2rps, which says something about the gun's comfortability and ease of use in my opinion. It shot blue rods up to an accuracy of about 5x5cm (2x2in) over 30ft, which is amazing for a Knex gun, and it was truly super comfortable. It wasn't even long at all, which is saying a lot, looking at some other people's attempts at 5-wide pump actions (I may also be guilty of an attempt several years ago). Being quite short and only 5 wide, it is also quite light. I'm sorry, I just really liked this gun, I think it was truly my best creation ever (of course, the S3 is by far the most innovative gun I've made, but it's mostly a concept gun, not meant for real effectiveness). I may post it in the future, but I'll make no promises. I suppose I won't leave you guys completely hanging and take a picture of it. Oh yes, there's also a neat, fun little thing I did, originally because I saw no other option, but then I actually really loved it. I'm talking about the mag-lock. It locks automatically (there's a band on it, but it ripped a long time ago, so...) and the mag cannot fall out. Then you pull on it with your middle finger, similar to a trigger, and the mag just drops right out. Love it :)

Posted by Sharir1701 3 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.

Posted by RT-101 6 years ago