Gasifier and Engine Research Project
In this UROP (Undergraduate Research Opportunity), I worked in the MIT Sloan Automotive Lab where I researched sending producer gas, created by a gasifier, into an engine to break down the tar and impurities, while generating power from cheap biomass. The objective was to modify the engine to clean the producer gas and generate power efficiently. The main difficulty with this project was handling the tar, which fouled up the surfaces and valves in the engine.
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Over the summer, I worked with Dr. Yu Chen, a post-doctorate at MIT, to set up the engine and gasifier for the experiments. At first, we took apart the engine to examine its condition and run tests before proceeding with farther set up. After observing abnormal pressures, we took apart the engine again to replace the pressure transducer. Once the pressure and temperatures were back to normal, we proceeded to set up a flow controller and piping into the engine.
When the gasifier arrived, we proceeded to connect the gasifier to the engine. However, the condition of the gasifier made reliably creating producer gas difficult. As a result, we disassembled the gasifier, discarded the cyclone, designed a new cylinder for the gasifier fuel hopper, and installed a flare to burn off any producer gas generated that wasn't sent to the engine.
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After the gasifier started to function reliably, we set up piping to the intake of the engine, creating junctions that led to a gas analyzer and tar collector to monitor the content of the producer gas and measure the amount of tar produced. We collected tar at both the intake and exhaust to compare later. We also insulated and installed process heaters on the piping to keep the pathway to the engine sufficiently warm so the tar does not condense on route to the engine.
At first, we were producing approximately 500 mg/m^3 of tar after running the gasifier through the engine for about an hour. Under normal operating conditions (ambient air, 400 degrees Celcius, ~35 bar in engine), there was a significant amount of tar at the intake and exhaust.
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As we continued experimenting, we adjusted the richness of the combustion by controlling the amount of air in the intake. As we ran richer experiments, we found there was a significant difference in tar produced at the exhaust and intake, revealing that the engine did break down the tar.
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However, after repeated experiments, the engine required regular cleanings to dispose of the tar that fouled the surfaces inside the engine before another experiment could be conducted.
