[en] Highlights: • Customized thermoelectric modules are fabricated for waste heat recovery. • A thermal resistance model is developed to simplify numerical simulations. • A plate fin structure is numerically optimized to improve conversion efficiency. • The numerical results are validated using experimental results and a correlation. • An equation is proposed to predict thermal resistances of fins in heat absorption. - Abstract: Thermoelectric modules (TEMs) are fabricated for a low-temperature waste heat recovery application. Each module has a surface area of 44 × 44 mm and a thickness of 3.6 mm, including a 1-mm-thick ceramic substrate on each side. Prior to fabrication of the system, a series of numerical simulations are conducted to optimize the design of the internal finned structures of a thermoelectric generator. To reduce the difficulty of designing the numerical models, a thermal resistance model is employed to determine the thermal conductivity of the TEM. The optimal number and thickness of the fin structures are determined with respect to the maximum allowable module temperature and the pressure drop characteristics. The accuracy of the numerical model is validated using an existing friction factor correlation and experimental results. The numerical results show that having six 2-mm-thick plate fins on the hot surface of each TEM would provide the most effective temperature fields for TE power generation while keeping the surface temperature of the TEM from exceeding the allowable maximum of ∼473 K. The pressure drop across the fins is found to increase with increasing number and thickness of fins. However, the module-level pressure drop is in the range of several pascals, which has a negligible effect on the combustion characteristics of the engine. A thermal resistance equation is proposed to predict the heat transfer characteristics of plate fins employed for thermoelectric generators for heat absorption.

[en] This report details our experimental study investigating particulate matter (PM) emissions from a diesel generator fueled with wood pyrolysis oil (WPO)–butanol blended fuel for electricity generation. Particle number-size distributions and PM mass concentrations from diesel, n-butanol, and WPO-butanol blended fuels were investigated via aerosol measurements using a fast mobility particle sizer and an aerosol monitor with three generator outputs (0, 3.3, and 6.6 kWe). For the n-butanol and WPO-blended fuels, the total number concentrations of exhaust particles were higher than that of conventional diesel combustion; however, the PM mass was observed to be nearly zero for all the engine operating conditions due to the higher number concentration in the nuclei mode. The morphology of the exhaust particles was investigated by analyzing transmission electron microscopy (TEM) micrographs. The morphology of the particles was drastically changed according to the test fuels and engine loads. Two types of particles were observed, including soot and coke shaped particles. These results were directly related to the immaturity of incipient soot particles due to the different physical properties and chemical compositions of the fuels.

[en] Blood-labyrinthine barrier leakage has been reported in sudden sensorineural hearing loss (SSNHL). We compared immediate post-contrast 3D heavily T2-weighted fluid-attenuated inversion recovery (FLAIR), T1 spin echo (SE), and 3D T1 gradient echo (GRE) sequences, and heavily T2-weighted FLAIR (hvT2F) with and without deep learning-based reconstruction (DLR) in detecting perilymphatic enhancement. Fifty-four patients with unilateral SSNHL who underwent ear MRI with three sequences were included. We compared asymmetry scores, confidence scores, and detection rates of perilymphatic enhancement among the three sequences and obtained 3D hvT2F with DLR from 35 patients. The above parameters and subjective image quality between 3D hvT2F with and without DLR were compared. Asymmetry scores and detection rate of 3D hvT2F were significantly higher than 3D GRE T1 and SE T1 (respectively, 1.37, 0.11, 0.19; p < 0.001). Asymmetry scores significantly increased with DLR compared to 3D hvT2F for experienced and inexperienced readers (respectively, 1.77 vs. 1.40, p = 0.036; 1.49 vs. 1.03, p = 0.012). The detection rate significantly increased only for the latter (57.1% vs. 31.4%, p = 0.022). Patients with perilymphatic enhancement had significantly higher air conduction thresholds on initial (77.96 vs. 57.79, p = 0.002) and 5 days after presentation (63.38 vs. 41.85, p = 0.019). 3D hvT2F significantly increased the detectability of perilymphatic enhancement compared to 3D GRE T1 and SE T1. DLR further improved the conspicuity of perilymphatic enhancement in 3D hvT2F. 3D hvT2F and DLR are useful for evaluating blood-labyrinthine barrier leakage; furthermore, they might provide prognostic value in the early post-treatment period. Ten-minute post-contrast 3D heavily T2-weighed FLAIR imaging is a potentially efficacious sequence in demonstrating perilymphatic enhancement in patients with sudden sensorineural hearing loss and may be further improved by deep learning-based reconstruction.