Performance analysis of an industrial waste heat‐based trigeneration system

The thermodynamic performance of an industrial waste heat recovery‐based trigeneration system is studied through energy and exergy efficiency parameters. The effects of exhaust gas inlet temperature, process heat pressure, and ambient temperature on both energy and exergy efficiencies, and electrical to thermal energy ratio of the system are investigated. The energy efficiency increases while electrical to thermal energy ratio and exergy efficiency decrease with increasing exhaust gas inlet temperature. On the other hand, with the increase in process heat pressure, energy efficiency decreases but exergy efficiency and electrical to thermal energy ratio increase. The effect of ambient temperature is also observed due to the fact that with an increase in ambient temperature, energy and exergy efficiencies, and electrical to thermal energy ratio decrease slightly. These results clearly show that performance evaluation of trigeneration system based on energy analysis is not adequate and hence more meaningful evaluation must include exergy analysis. The present analysis contributes to further information on the role of exhaust gas inlet temperature, process heat pressure, ambient temperature influence on the performance of waste heat recovery‐based trigeneration from a thermodynamic point of view. Copyright © 2009 John Wiley & Sons, Ltd.     

Analysis of a Multiphase Induction Machine Under Fault Condition in a Phase-Redundant A.C. Drive System

Phase-redundancy is a unique technique for improving the reliability of large variable speed AC drives. This technique, derived from the concept of parallel-redundancy, is based on the capability of a multiphase machine to start and continue running with one or more of its many stator phases open or short circuited with lower performance. Structural unbalance in the machine following loss of excitation is the main source of performance degradation. This paper, therefore, presents a simple generalized approach to analyze the dynamic as well as steady-state behavior of a multiphase induction machine during fault condition in a phase-redundant AC drive system. The key analytical results have been experimentally verified by tests conducted on a laboratory prototype.     

Poly(3-hexylthiophene) and hexafluoro-2-propanol-substituted polysiloxane based OFETs as a sensor for explosive vapor detection

The organic field effect transistors (OFETs) with regioregular poly 3-hexylthiophene (rr-P3HT) and hexafluoro-2-propanol-substituted polysiloxane (SXFA) as an organic layer, have been used for detection of explosive vapors with excellent sensitivity of less than 70 ppt for 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX) and less than 100 ppt for 2,4,6-trinitrotoluene (TNT). The sensor response (% change in saturation current) was found to be 125 ± 10% for TNT and 90 ± 10% for RDX. It was also observed that the incorporation of Cu^II tetraphenylporphyrin (CuTPP) into rr-P3HT/SXFA matrix resulted in an improved selectivity for the vapors of nitro based analytes (TNT, RDX and DNB) as compared to the vapors of non explosive oxidizing agents such as nitrobenzene (NB), benzoquinone (BQ) and benzophenone (BP). This is attributed to the increased binding of the vapors containing nitro compound to the thin films due to the presence of CuTTP. Spin coated thin films were further characterized by Atomic Force Microscopy (AFM) and Electrostatic Force Microscopy (EFM).     

Iodine‐Mediated Copper‐Catalyzed Efficient α‐C(sp2)‐Thiomethylation of α‐Oxoketene Dithioacetals with Dimethyl Sulfoxide in One Pot

The direct α‐Csp² H functionalization and thiomethylation of α‐oxoketene dithioacetals (DTAs) has been accomplished with dimethyl sulfoxide (DMSO) in the presence of iodine and a copper(I) salt for the first time. A prerequisite is the in situ iodination of the α‐Csp² atom of dithioacetals that could offer other reaction channels. The operationally simple one‐pot protocol includes region‐defined consecutive iodination and sulfenylation of the challenging α‐Csp² H bond of dithioacetals employing cheap and readily available reagents. DMSO here plays a dual role as thiomethyl source and solvent.

     

Deformation Behavior of Metastable Austenitic Steel at Low and Moderate Temperatures

Metal Science and Heat Treatment - The TRIP effect and deformation behavior of metastable austenitic steel were studied under tension in the temperatures range from –120 to +200°C. The...     

Effect of Retrogression and Re-Aging on Tensile Mechanical Properties in Transverse Direction of Extruded Rods from Aluminum Alloy AA7049

Metal Science and Heat Treatment - The effect retrogression and re-aging (RRA treatment) on the tensile properties in the transverse direction of extruded rods from aluminum alloy AA7049 is...     

Study of Temperature Dependence of Electrode–Glass Ceramic Interface Using Impedance Spectroscopy

The electrical behavior of strontium titanate borosilicate glass ceramics (SrO.TiO₂- 2SiO₂.B₂O₃) with additives K₂O, La₂O₃, CoO and Nb₂O₅ was studied by using Impedance Spectroscopy as a function of temperature and composition. An equivalent circuit model having three parallel RC's connected in series with a capacitor C₄ could represent the data well. By comparing the complex modulus plots with simulated ones and looking at the values of the time constants these RC's were attributed to represent crystalline, glassy and glass-crystal interface regions of the glass- ceramic whereas C₄ represented the glass-ceramic sample and contact electrode interface. When the glass ceramic sample contained only SrTiO₃ crystalline phase and the remaining glassy matrix, the interface capacitance showed an Arrhenius type of nature with an activation energy (0.11 ± 0.04) eV and when the glass- ceramic sample contained number of crystalline phases no clear cut trend appeared. These findings are useful in selecting suitable electrodes for applications as well as in deciding upon experimental techniques for measurement of dielectric constants of materials.     

Towards Supramolecular Catalysis with Small Self-assembled Peptides

Self-assembly of small peptides offers unique opportunities for the bottom-up construction of supramolecular catalysts that aim to emulate the efficiency and selectivity of natural enzymes. Small, information-rich, simple molecules based on amino acids can self-organise autonomously into complex systems with emergent catalytic properties. The power of noncovalent interactions can be used to construct supramolecular peptidic tertiary structures. Moreover, specific functional groups present in amino acid side-chains may present either a catalytic activity by themselves or be able to bind cofactors such as metal ions. In this scenario, although relevant progress has been achieved in recent years, promising applications in biomaterials science are foreseen. In this review, we discuss the state-of-the-art of this approach at the interface between supramolecular chemistry and peptide science.