Planning experiments

Understanding the theory of combustion and heat transfer in a stove can only help so much with the design.  To understand the performance of the current rocket stove design more, experiments need to be performed (experimentos son necesario para entender como es la functión de la estufa de cohete).  Unfortunately, we don’t have the funds for laser absorption diagnostics in Xela.  So what tools can we use for experimentation?  (No tenemos herrmientas por absorbción de lasers en Xela.  ¿Entonces, que herrmientas pedemos usar medir cosas en experimentos?) 

The company I’m working with has a few tools for experimentation.  I have two thermocouples, one with a limit near the boiling temperature of water, and one with a limit of roughly 773 Kelvin.  I can also use an IR temperature sensor to measure surface temperatures on non-reflective surfaces.  Furthermore, I have access to a scale to measure weight.  What would really be useful would be if I could monitor the air flow velocity, and that could give me a sense of the air-fuel ratio.  Additionally, a method to monitor soot would be helpful to determine how complete the combustion process is.  We started up the stove and played with the tools we had, and also several other methods of monitoring things.  The temperature measurements seem fine.  I explored a poor man’s soot diagnostic by putting a piece of clean pumice stone in the gas flow chamber (la idea gracias a Adela) – after a few minutes, the pumice stone will begin to darken from the soot, and using this monitoring technique I may be able to determine whether more or less soot is formed in different stove configurations.  To make more quantitative soot measurements, a particle counting device can be purchased for about $200, though this won’t happen in the time that I’m here.  We explored the air flow velocity by lighting another starter stick of wood and placing it near the air inlet of the stove, and by watching the flame enter the air inlet we could tell that there was substantial airflow.  I doubt this would yield a very good quantitative measurement of air flow velocity, but maybe by measuring the angle of the flame entering the air inlet I might be able to determine whether changing the flow geometry inside the stove has a significant effect on the air flow velocity. 

My planned experiments include time-to-boil tests.  In these tests, I will make lots of temperature measurements and ad hoc soot and velocity measurements.  And maybe a tortilla cooking test will occur as well. (Voy a medir la temperatura en muchos lugares y voy a tratar de medir hollín y velocidad de aire.  Haré un experimento de cocinar tortillas también).

Results to come.  Experimental suggestions welcome.