While conventional thermoelectric (TE) systems have carved out a niche in specialized thermal management applications that can benefit from their small size and solid-state operation, these systems have efficiency and capacity shortcomings that limit their broader adoption. Our patented distributed transport properties (DTP) technology will enhance the performance landscape of thermoelectric systems, enabling new applications in automotive, cold chain, medical and other applications in which conventional thermoelectrics could not compete.
DTP is a new thermoelectric cooling and temperature control technology in which the transport properties — Seebeck coefficient, electrical resistivity and thermal conductivity — are spatially optimized within the thermoelectric material. DTP materials are tuned to achieve optimal cooling, heating and temperature control characteristics.
This figure illustrates Seebeck coefficient (S) varying with position in a thermoelectric (TE) cooling couple consisting of N and P type elements. Toward the hot end, the spatially varying Seebeck coefficient in the N type TE material is progressively more negative, while the coefficient in the P type material is progressively more positive.
By varying the Seebeck coefficient, electrical resistivity and thermal conductivity throughout the length of the couple, the DTP material structure changes to closely match the shape that creates optimum performance.
DTP technology delivers large performance gains to TE systems. Our numerical modeling, for example, shows that a single-stage DTP thermoelectric device can achieve a maximum temperature difference (DT) of more than 130 K based on a hot side temperature of 300 K, versus 73 K for a single-stage standard thermoelectric (TE) module operating in cooling mode. A cascaded standard TE module can reach 130 K as well, but DTP TE modules can also be cascaded, extending their DT even further. DTP TE systems also provide efficiency gains of 140% and a cooling power advantage of 200% compared to standard TE systems.
DTP Versus Conventional Thermoelectrics
Input Power Versus Temperature Difference
Cooling Maximum COP for DTP and CTE Systems
Advances in manufacturing techniques and materials systems have only recently made DTP thermoelectric systems a practical reality. A number of processes have emerged that can cost-effectively produce DTP materials with spatially distributed thermoelectric properties — including spark plasma sintering, ion implantation and additive manufacturing. At the same time, DTP technology lends itself to the use of alternative thermoelectric materials, which may be more cost-effective or exhibit higher figures of merit. For example, the DT advantage in our numerical study came not only from the use of DTP but also alternative thermoelectric materials. There is ample headroom for future performance gains as DTP fabrication and material technologies mature.