Tag Archive for: LEMS

Computer screen shows emissions rates as lines on a graph

Designing an Optimized Forced Draft Insert

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David Evitt, ASAT COO, and Sam Bentson, ARC GM, have been adding capacity to the Laboratory Emissions Monitoring System (LEMS). So far, four oxygen sensors, temperature probes in the fire and under the pot, and a velocity sensor give us a clearer picture of what’s going on in a stove. Knowing PM2.5, CO, CO2, and firepower at the same time, combined with the improved testing protocols in ISO 19867, is making us more confident that iterative improvement can be accomplished relatively quickly.

During a test, the LEMS screen shows real time emission rates of CO2 (blue line), CO (red line), and PM2.5 (black line).

Starting in early December, Dean Still and a research assistant will be doing 20 tests per week to create an optimized forced draft insert that cleans up the combustion of found biomass fuels and improves thermal efficiency in open fires, high mass, and Rocket stoves. A screen in the hood showing real-time data helps reduce the needed repetitions to achieve statistical confidence.  The 90% confidence interval has to be less than 1/3 of the range of the Tier that contains the conservative bound of the confidence interval. When Tier Confidence Interval Range is equal to or less than 0.33, the number of tests is deemed sufficient to meet the Aprovecho data repeatability quality standard (seven to nine tests each for high, medium, and low power are usually sufficient).

David is in grad school with Dr. Nordica MacCarty at Oregon State University and the ARC lab is supplying them with information. We’ll keep you in the loop as we make discoveries. Part of the goal is to keep the optimized insert as close to a $10 wholesale price as possible.

Here we go! Eco-Science marching forward!

Sam Bentson trains Bernard Kabera and colleagues to use the new stove lab equipment

Setting Up a New Lab in Rwanda

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Aprovecho’s General Manager Sam Benston recently returned from a trip to Rwanda, where he helped to set up a new ISO compliant cookstove lab. Here are some photos and information from Sam about his work there:

I was installing the LEMS (Laboratory Emissions Monitoring System) and PEMS (Portable Emissions Monitoring System) and the rest of the new ISO 19867 cookstove laboratory at the Rwanda Standards Board in Kigali. The lab started as an empty room full of equipment in boxes. I trained the laboratory staff on the set-up and use of the equipment for cookstove evaluations according to ISO 19867. Shortly after I left there was a Grand Opening to celebrate on the ISO’s World Standards Day. Here is a twitter link with photos:  https://twitter.com/REMA_Rwanda/.  Our new PEMS with the battery powered gravimetric system is visible.

The PEMS is visible here at the launch of the Cook Stove testing lab in Kigali
The PEMS is visible here at the launch of the Cook Stove testing lab in Kigali.
Photo via @REMA_Rwanda

Aprovecho provides a turnkey cookstove testing laboratory which is useful for cookstove performance certification, design, and basic research. The lab is centered around the ARC manufactured LEMS. It consists of a gas and particle analyzer with a pump and filter PM2.5 sampler, an emissions collection hood, and a dilution tunnel. The LEMS is the result of 20 years of development that started due to the lack of affordable and easy to use equipment suitable for cookstove emissions monitoring.

Testing a stove under the new LEMS hood.
Testing a stove under the newly installed LEMS hood.

Aprovecho develops its equipment as the need arises during research and development activities that occur in its laboratory. Aprovecho’s ability to commission the other instruments that makeup a cookstove testing laboratory is the result of a similar depth of experience.

Bernard Kibera and colleagues training to use the new stove lab equipment
Mr. Bernard Kabera and colleagues training to use the new stove lab equipment.
Sam Bentson trains Bernard Kibera and colleagues to use the new stove lab equipment
Sam Bentson trains Mr. Bernard Kabera and colleagues to use the new stove lab equipment.

It was remarkable to observe how the Rwandan people have protected themselves against COVID. It was a great honor to be part of their community at this time.

–Sam Bentson