Thermoelectric development at Hi-Z technology

An improved thermoelectric generator (TEG) for the heavy duty class eight diesel trucks is under development at Hi-Z Technology. The current TEG is equipped with the improved HZ-14 thermoelectric module, which features better mechanical properties as well as higher electric power output. Also, the modules are held in place more securely. The TEG is comprised of 72 TE modules, which are capable of producing 1 kW of electrical power at 30 V DC during nominal engine operation. Currently the upgraded generator has completed testing in a test cell and starting from August 2001 will be tested on a diesel truck under typical road and environmental conditions. It is expected that the TEG will be able to supplement the existing shaft driven alternator, resulting in significant fuel saving, generating additional power required by the truck´s accessories. The electronic and thermal properties of bulk materials are altered when they are incorporated into quantum wells. Two-dimensional quantum wells have been synthesized by alternating layers of B₄C and B₉C in one system and alternating layers of Si and Si_0.8Ge_0.2 in another system. Such nanostructures are being investigated as candidate thermoelectric materials with high figures of merit (Z). The predicted enhancement is attributed to the confined motion of charge carriers and phonons in the two dimensions and separating them from the ion scattering centers. Multilayer quantum well materials development continues with the fabrication of thicker films, evaluation of various substrates to minimize bypass heat loss, and bonding techniques to minimize high contact resistance quantum well thermoelectric devices with N-type Si/Si_0.8Ge_0.2 and P-type B₄C/B₉C have been fabricated from these films. The test results generated continue to indicate that much higher thermoelectric efficiencies can be achieved in the quantum wells compared to the bulk materials