Overview graphic of the research goal: to characterize and extend the fuel-flexibility of small- scale, portable power systems. 

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... electronics are getting smaller and the power supplies that drive them also need to shrink in order to address market demand [1]. Specifically, fuel flexible portable power is utilized by the military for special ops missions [2], emergency crews for disaster relief communication needs and potentially auto manufacturers for fuel-flexible hybrid vehicles, enabling better access for renewable fuel consumption. And as portability improves, so increases the need for fuel flexibility in that energy sources vary across every region in the world. Currently, significant gaps in technology remain as portability requires robustness, light-weight design and mobility; each which typically compete with high power and high energy density. Liquid-based hydrocarbon fuels have been identified to meet these requirements and can be converted into electrical power via fuel-flexible engine generators [ 3]. Other competitive alternatives are bulky, have slow recharge times, lack fuel flexibility or are not robust. Therefore, a high power density solution using a robust 4.97 cc Wankel engine that converts liquid chemical energy from a variety of fuels into useable output power on the range of 10-1000 W was chosen for these types of applications (Figure 1). Many researchers are working to solve the small- scale portable power problem [4]. Pello et al . are researching mini and micro combustion environments present in small-scale rotary engines. Pisano et al . have made advancements in the fabrication of MEMS-based rotary engines [3]. Dunn Rankin et al. focus on mini engines and their performance [5]. Building upon the aforementioned work, this research attempts to enable small-scale power supplies that have essentially zero recharging times, can convert nearly any liquid hydrocarbon into usable power, up to one horsepower. The technical challenges with miniaturizing engines are split into two broad categories: thermal and chemical management [4]. The following represent the most problematic: heat transfer, sealing, stoichiometry and the turbulent mixing of fuel and air are most common [6]. However, in this research, the focus is making fuel flexibility more robust. Because engines are typically designed around one fuel, the challenge became creating a system composed of engine peripherals and controls that permit wide range fuel flexibility. This included sensors, actuators and software to dynamically adjust engine parameters along with a multi-fuel switching system to deliver many fuels to the engine in real time. Additionally, a more accurate and complete small- scale engine characterization system was needed as the data would drive future engine / sensor ...