A Thermophotovoltaic Catalytic Flow Reactor for Portable Power Generation.
batteries are the standard technology for potable power generation, they have relatively
low energy densities: on average 0.2 kWhr/kg. Hydrocarbons, on the other hand, can have
energy densities as high as 12 kWhr/kg, such that even an inefficient fuel-powered
portable generator could surpass the performance of state of the art batteries.
Moreover, while some of the most ... read moreenergy-dense batteries are non-rechargeable, simply
refueling can quickly recharge a hydrocarbon-powered supply. Traditional heat engines,
however, do not scale well: micro-heat engines are plagued with friction losses due to
moving parts. The larger surface-area-to-volume ratio also leads to increased heat
losses, which prevent a sustained reaction from occurring. A promising alternative for
small-scale portable power applications incorporates Thermophotovoltaics (TPV) in place
of a heat engine. Instead of converting the heat to mechanical energy, the heat is
directly converted to electricity through traditional photovoltaic mechanisms. Unlike
micro-engines, TPVs are structurally simple and have no moving parts. A propane-fueled
TPV generator could significantly extend the "battery lifetime" of portable electronic
devices. Consumer, military, medical, and remote sensing devices would benefit from
developments in this field. Here, we design and implement a combustion system that will
supply radiant energy to TPV. This project is twofold: First, there is the design and
testing of a novel meso-scale combustion system. Propane fuel is catalytically combusted
by a platinum-plated nickel foam insert. With a fuel to air equivalence ratio of Φ
= 0.83, a combustion efficiency of 7.4% is achieved. Second, we investigate methods for
extending the operational wavelengths of TPV devices, which are needed to optimally
convert the meso-combustor emission spectrum. We employ a superlattice barrier structure
to suppress diffusion currents, decreasing dark current and improving overall power
characteristics. Through simulation with Silvaco software we find that the barrier
structure improves the relative diode efficiency by 26.5%. Finally, we investigate the
limit for longer wavelength devices based doping-restraints and intrinsic carrier
concentrations for room-temperature
Thesis (M.S.)--Tufts University, 2015.
Submitted to the Dept. of Electrical Engineering.
Advisor: Thomas Vandervelde.
Committee: Thomas Vandervelde, Marc Hodes, and Ron Lasser.
Keyword: Electrical engineering.read less