Optimization of All-Oxide 2D Layered Thermoelectric Device Fabricated by Plasma Spray
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Optimization of All-Oxide 2D Layered Thermoelectric Device Fabricated by Plasma Spray Felipe R. Caliari1 • Hwasoo Lee1 • Sanjay Sampath1
Submitted: 12 May 2020 / in revised form: 30 July 2020 Ó ASM International 2020
Abstract Harvesting waste energy using thermoelectric (TE) principles is a key technology that increases overall power conversion and efficiency from combustion-based energy generation systems. However, design restrictions of commercially available thermoelectric devices and toxicity of commercial thermoelectric materials currently limit large-scale deployment. Additive and multilayered design and manufacturing of thermoelectric modules are a potential pathway to overcome current design restrictions as it enables to implement the device directly to the engineering structures with direct access to waste heat. Plasma spray is the chosen technology in this work to fabricate such patterned and layered TE devices, using as p-type Ca2Co2O5 and the n-type material TiO2-x. The optimization of thermoelectric leg geometry results in a maximum power density output of 1.9 9 10-4 W/cm2 per couple and efficiency of 1.1% at 750 K. An important aspect of this TE device design is that it allows direct p-n contact, whereas the proportionality between p-n contact area and power output is demonstrated. A correlation between the coating thickness and nonlinear behavior of the thermoelectric voltage is also discussed, which is associated with the anisotropy degree of the n-type coating. Keywords atmospheric plasma spray calcium cobaltite layered additive manufacturing non-stoichiometric TiO2-x thermoelectric properties
& Felipe R. Caliari [email protected] 1
Center for Thermal Spray Research, Stony Brook University, Heavy Engineering, Bldg. Rm 130, Stony Brook, NY 11794-2275, USA
Introduction The endless demand for sustainable and clean energy requires the development of disruptive and smart technologies capable of enhancing the power conversion from combustion-based to electrical energy. Thermoelectric (TE) power generation is a potential approach that can augment current heat engine technologies by harvesting the waste heat from the thermal source and converting into useful electrical energy for enhanced efficiencies and reducing losses (Ref 1-3). The phenomenon of thermoelectricity for power generation depends on the formation of an electric field gradient upon application of a temperature gradient, known as Seebeck coefficient (S). In addition, the transport of heat and electricity by the charge carriers also accounts on the power conversion. To understand the overall thermoelectric efficiency of a given material, so-called thermoelectric figure of merit, ZT is used, ZT ¼
S2 T qk
where S, q, k and T are the Seebeck coefficient, resistivity, thermal conductivity and absolute temperature. Efforts from both academia and industrial research and development are focused on enhancing the performance of thermoelectric materials and devices to efficiently convert the usable heat to pow
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