Design and Analysis of a Thermoelectric HVAC System for Passenger Vehicles

Global pressures to reduce CO₂ emissions and to lessen the influence of petroleum imports on national economies have accelerated the electrification of automotive power plants. The paradigm shift is driving investment in technologies aligned with electrification, such as electric motors and batteries. It also introduces new challenges for vehicle designers to manage the integration of new subsystems required by electrification. One consequence of increased electrification is a greater difficulty providing occupant thermal comfort. For the first time, automotive system developers must consider the energy required to heat as well as cool occupants and provide thermal management for a growing suite of electronic equipment. With the phasing out of R-134a in Europe over 2011 to 2017, alternative two-phase vapor compression systems utilizing refrigerants such as CO₂ or R-134A replacements have drawbacks of either being costly or flammable and lack long-term sustainability given the increasing electrification of powertrains. Under these circumstances, solid-state and refrigerant-free thermoelectric systems are a leading candidate to provide vehicle heating and cooling. Moreover, they can cool and heat with the same components and provide engine-off HVAC function including cabin preconditioning.

This paper presents a thermoelectric air-liquid system designed with the aid of a numerical model. The model was used to solve for the optimal combination of up to 14 variables to achieve the best system performance and cost under given conditions. A TE device was built and tested to validate the model. The device is capable of supplying up to several thousand watts of thermal output power in heating and cooling modes of operation. Good agreement was found between the simulation results and the test data.