ABSTRACT
The complete simulation model of an existing 1 kW high-temperature proton exchange membrane (HT-PEM) fuel cell-based residential micro-combined heat-and-power process, including a compact intensified heat-exchanger-reactor, is developed in the simulation software ProSimPlus v3.6.16. Detailed simulation models of the heat-exchanger-reactor, a mathematical model of the HT-PEM fuel cell, and other components are presented. The results obtained by the simulation model and by the experimental micro-cogenerator are compared and discussed. To fully understand the behavior of the integrated system and assess its flexibility, a parametric study is performed considering fuel partialization and important operating parameters. The values of the air-to-fuel ratio = [30, 7.5] and steam-to-carbon ratio = 3.5 (corresponding to net electrical and thermal efficiencies of 21.5 and 71.4%) are chosen for the analysis of inlet/outlet component temperatures. Finally, the exchange network analysis of the full process proves that the process efficiencies can still be increased by further improving the process internal heat integration.
ABSTRACT
In this paper, we report on a continuous-flow microreactor process to prepare ZnO quantum dots (QDs) with widely tunable particle size and photoluminescence emission wavelengths. X-ray diffraction, electron diffraction, UV-vis, photoluminescence and transmission electron microscopy measurements were used to characterize the synthesized ZnO QDs. By varying operating conditions (temperature, flow rate) or the capping ligand, ZnO QDs with diameters ranging from 3.6 to 5.2 nm and fluorescence maxima from 500 to 560 nm were prepared. Results obtained show that low reaction temperatures (20 or 35 °C), high flow rates and the use of propionic acid as a stabilizing agent are favorable for the production of ZnO QDs with high photoluminescence quantum yields (up to 30%).
