Analysis & characterization of a flow thermo-electrochemical cell for power generation & heat convection

Abstract

In this thesis, I analyzed and characterized a new flow thermo-electrochemical cell that generates power from waste-heat, while in parallel convecting this heat away from the source. I also reviewed previous research on the topic of thermo-electric energy generation, governing physics behind thermo-electrochemical energy generation, actual device fabrication, device testing, results, and applications of this technology. Thermo-electric devices (TE devices) exhibit the thermo-electric effect, where temperature gradients and material properties work in tandem to drive electron transfer at electrode surfaces, thereby generating electricity. For example, a typical sold-state TE device such as a bismuth telluride TE device, can generate up to 0.300 mV/K [31]. New reseach has emerged [25, 26, 14] focusing on liquid-based thermo-electrochemical (TEC) cells that take advantage of the temperature dependence of oxidation/reduction chemical reactions to generate electricity. One of the major benefits of these TEC devices over traditional TE devices is a much higher S, = 1.5 mV/K; another is the low cost of manufacturing, making them promising for commercial applications. The new TEC device that I fabricated and studied utilizes a flowing electrolyte instead of a stationary electrolyte. With this new configuration, and a heated boundary condition, I studied both the energy generation and convective heat transfer capabilities of the flowing electrolyte TEC cell. Numerically I obtained a maximum power output and heat transfer coefficient for the TEC cell of Pmax = 2.6 [mu]W and h = 340 W/m²K which corroborates well with the experimentally found value of Pmax = 2.0 [mu]W and h = 450 W/m². K. If employed in data centers, as a device for CPU cooling, with the given power output I found that a 100,000 ft² data center can generate about 21.96 MWh of energy, which at a cost of 0.20 $/kWh can save a data center about 5,000 $/year. More generally, the application of this technology in locations where waste-heat is prevalent, will allow for energy recycling and consequent cost savings.