Characterization and Modeling Quality Analysis of Edible Oils Using Electrochemical Impedance Spectroscopy.

The dielectric characteristics of six culinary oils were measured over the frequency range of 0.01 Hz-100 kHz. The results showed that the dielectric constants of oils had the same frequency relationship (i.e., they decreased with increasing frequency). The dielectric constants at lower frequencies for olive oil A, olive oil B, sesame oil, Nigella sativa, sunflower oil, and corn oil are approximately 2.75, 2.5, 2.0, 1.75, 1.5, and 0.9. An FT-IR analysis showed that the spectral differences were very small, because most vegetable oils contain the same type of fatty acids. The model built using COMSOL Multiphysics for the potential and electric field distributions for different oils and used to calculate the dielectric constant was simulated under various conditions in the AC/DC module. The model results were compared with the experimental results, which showed satisfactory convergence between them. The experimental and model results obtained in this study could be useful for evaluating the edible oil quality.

Comparison of different adsorption pairs based on zeotropic and azeotropic mixture refrigerants for solar adsorption ice maker.

One of the important ways to the efficiently use of low-grade thermal energy is the adsorption refrigeration technology. However, it has some drawbacks such as low specific cooling power and coefficient of performance, especially under using the conventional adsorption pairs. Therefore, new adsorption pairs are tested in solar adsorption ice-maker and compared with other conventional pairs data from open literature to find the tendency of improving the solar adsorption ice-maker performance. The experimental test rig has been built in Upper Egypt in Qena City. Four different new adsorption pairs of granular activated carbon/R-410A, granular activated carbon/R-511A, Maxsorb III/R-410A, and Maxsorb III/R-511A are used. It is demonstrated that Maxsorb III/R-511A pair based solar adsorption ice-maker produced the highest values for specific cooling power, coefficient of performance, and ice production per 1 kg of adsorbent of approximately 226.7 W/kgads, 0.197, and 1.96 kg/kgads, respectively. While granular activated carbon/R-410A based solar adsorption ice-maker produced the lowest values of ice production per 1 kg of adsorbent and coefficient of performance of 1.38 kg/kgads and 0.104, respectively. Moreover, it can be concluded that the tested pairs are feasible to be used in solar adsorption ice-maker systems, especially in such hot climate of Upper Egypt for food and vaccine preservation and storage.

Effects of growth technique on the microstructure of CuInSe 2 ternary semiconductor compound.

X-ray diffraction (XRD) and Energy-dispersive X-ray fluorescence spectrometer (EDXRF) are employed to investigate the microstructure of bulk C u I n S e 2 specimens grown through the Bridgman technique and traveling heater process, respectively. We investigate the lattice parameters, grain sizes, and microstrains of the two grown samples. For a crystal grown by the vertical Bridgeman method, the vacancy V C u serves as an acceptor, resulting in p-type conduction, whereas the vacancy V S e expected to serve as a donor, occurring in n-type conduction for the crystal grown via the traveling heater technique. The concentration of crystal grown via the VBM is determined to be p-type, whereas the concentration of that grown via the THM is n-type. Concerning C u I n S e 2 crystal, the determined crystallite sizes obtained to be 165 and 182 nm for the VBM and THM, respectively.