Students create device that reduces lawn mower emissions

May 15, 2013 -  By

Leave it to enterprising engineering students to develop a way to reduce lawn mower emissions.

A team of University of California, Riverside Bourns College of Engineering students created a device that attaches to a lawn mower and significantly cuts its harmful emissions. With some design modifications, the device also could be used on leaf blowers, dirt bikes and snowmobiles, which the California Air Resources Board also has targeted for reduced emissions.

Although emissions from large engines, such as those in automobiles and trucks, are highly regulated, small engines usually are not subject to similar rules. That is changing, however, as studies show small engine devices produce between 100 to 1,000 times more emissions than automobiles over the same operating time.

The team of student, which calls itself NOx-Out, believes there is a market for the device from lawn mower manufacturers that are subject to new regulations in California. They also think there is a market for current lawn mower owners who could retrofit their existing gasoline-powered lawnmower with the device to create a more environmentally friendly lawn mower. As an added bonus, the device also reduces lawn mower noise and gasoline odors.

The team of students–Joshua Callihan, Rosalva Chavez, Jonya Blahut, Risa Guysi and Holly Clarke–recently won two first place awards at the WERC: A Consortium for Environmental Education and Technology Development competition in Las Cruces, N.M., run by the Institute for Energy & the Environment.

They shared a first place honor in one category and won first place in the peer award category, which is judged by students at the competition. In total, they won $2,250. Their adviser is Kawai Tam, a lecturer at the Bourns College of Engineering.

The students, who are all seniors and are all environmental engineering majors with the exception of Callihan (a chemical engineering major), created the device, which can be attached to a lawn mower in the place of the muffler. When they tested it at the Bourns College of Engineering Center for Environmental Research and Technology, it reduced these harmful pollutants: carbon monoxide by 87 percent; nitrogen oxides by 67 percent and particulate matter by 44 percent.

The idea for the device originated about a year ago. Chavez had a conversation with a member from a University of California Riverside team that won awards at last year’s WERC competition. That team member mentioned that the judges were interested in small engine projects. Chavez thought of her father, who cuts lawns to earn extra money and had developed asthma, and wondered whether the two were linked.

After Chavez talked to her father, Blahut had a conversation with her father, who is a truck driver and recently had to retrofit his truck with a particulate matter filter. She wondered whether a similar filter could be attached to a lawn mower.

She and her teammates found out it could. The device they created is about six inches long. It consists of a filter, a glass jar that holds two ounces of urea solution, the original lawn mower muffler, which the students modified by packing with a catalyst they created, and a series of stainless steel nuts and bolts that connect everything and attached to the lawn mower muffler port.

The device can be thought of as a three-stage system. First, a glass quartz filter captures particulate matter. Then an ultra-fine spray of urea solution is dispersed into the exhaust stream. The urea spray primes the dirty air for the final stage, when a catalyst converts the harmful nitrogen oxide and ammonia into harmless nitrogen gas and water and releases them into the air.

The key to the process is the catalyst the students developed. The students do not want to identify what it is made of because it is a novel product that they are considering patenting. Similar catalysts have been developed for diesel fuel, but not for gasoline.

The students expect to sell the device for $30, which would also include a 16-ounce refill bottle of the urea solution and 10 quartz replacement filters. They plan to improve the design, however, by replacing the glass jar with another material that is less prone to breakage and designing and machining a single piece of stainless steel to replace the various nuts and bolts they currently have connected to form the device.

They are considering starting their own company to sell the device or selling the idea to a lawn mower manufacturer. The students say no similar aftermarket emission control device exists for lawn mowers.

The team sponsors were Watson Bros.; OXY USA Inc. LA Basin Asset; BPS – Long Beach, a UC Riverside Undergraduate Research Grant; University of California Riverside’s College of Engineering Center for Environmental Research and Technology; Signal Hill Petroleum; Bill Summerfield, who works at Signal Hill Petroleum; and Don Clarke, Holly Clarke’s father.

The team also received assistance from two University of California Riverside professors: David Cocker, a professor of chemical and environmental engineering, and Phil Christopher, an assistant professor of chemical and environmental engineering.

To view a video of the team and the device, visit YouTube.

 

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