Posts about mechanical engineering

Engineering a Better World: Bike Corn-Sheller

photo of bike maize sheller

More appropriate technology from MIT’s D-Lab.

D-Lab-developed device makes corn processing more efficient

Jodie Wu, an MIT senior in mechanical engineering, spent the summer traveling from village to village in Tanzania to introduce a new system for processing the corn: A simple attachment for a bicycle that makes it possible to remove the kernels quickly and efficiently using pedal power. The device makes processing up to 30 times faster and allows one person to complete the job alone in one day.

The basic concept for the maize-sheller was first developed in Guatemala by an NGO called MayaPedal, and then refined by Wu last semester as a class project in D-Lab: Design, a class taught by Department of Mechanical Engineering Senior Lecturer Amy Smith. Now, thanks to Wu’s efforts, the technology is beginning to make its way around the world.

Thus, the owner of a bicycle, with a small extra investment, can travel from village to village to carry out a variety of useful tasks. A simple bike thereby becomes an ongoing source of income.

Wu refined the corn-sheller system, which was originally designed as a permanent installation that required a bicycle dedicated solely to that purpose, to make it an add-on, like Kiwia’s tools, that could be easily bolted onto an ordinary bike and removed easily.

Photo shows the prototype of the attachment. Engineering that makes a significant difference in people’s lives (especially those that need it the most) is even cooler than the latest high tech gizmos in my opinion. And those new gizmos are cool.

Related: Design for the Unwealthiest 90 PercentAppropriate Technology postsWater Pump Merry-go-RoundNepalese Entrepreneur Success – Tumaini Cycles blog (by

Cost Efficient Solar Dish by Students

Solar Energy Dish

Low-cost system could revolutionize global energy production

A team led by MIT students this week successfully tested a prototype of what may be the most cost-efficient solar power system in the world – one team members believe has the potential to revolutionize global energy production.

The system consists of a 12-foot-wide mirrored dish that team members have spent the last several weeks assembling. The dish, made from a lightweight frame of thin, inexpensive aluminum tubing and strips of mirror, concentrates sunlight by a factor of 1,000 – creating heat so intense it could melt a bar of steel.

To demonstrate the system’s power, Spencer Ahrens, who just received his master’s in mechanical engineering from MIT, stood in a grassy field on the edge of the campus this week holding a long plank. Slowly, he eased it into position in front of the dish. Almost instantly there was a big puff of smoke, and flames erupted from the wood. Success!

Burning sticks is not what this dish is really for, of course. Attached to the end of a 12-foot-long aluminum tube rising from the center of the dish is a black-painted coil of tubing that has water running through it. When the dish is pointing directly at the sun, the water in the coil flashes immediately into steam.

Someday soon, Ahrens hopes, the company he and his teammates have founded, called RawSolar, will produce such dishes by the thousands. They could be set up in huge arrays to provide steam for industrial processing, or for heating or cooling buildings, as well as to hook up to steam turbines and generate electricity. Once in mass production, such arrays should pay for themselves within a couple of years with the energy they produce.

“This is actually the most efficient solar collector in existence, and it was just completed,” says Doug Wood, an inventor based in Washington state who patented key parts of the dish’s design–the rights to which he has signed over to the student team.

Great job students. Good luck with RawSolar. Photo (by David Chandler): Matt Ritter shows steam coming from the return hose after passing through the coil above the solar dish.

Related: Cheap, Superefficient SolarSolar Thermal in Desert, to Beat Coal by 2020Solar Tower Power GenerationEngineering Students Design Innovative Hand Dryerposts on solar energy