• Energy Research

In this study, zeolitic imidazolate framework (ZIF-67) derived nano-porous carbon structures that were further hybridized with MnO2 were tested for oxygen reduction reaction (ORR) as cathode material for fuel cells. The prepared electrocatalyst was characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and Energy Dispersive X-ray Analysis (EDX). Cyclic voltammetry was performed on these materials at different scan rates under dissolved oxygen in basic media (0.1 M KOH), inert and oxygen rich conditions to obtain their I–V curves. Electrochemical impedance spectroscopy (EIS) and Chronoamperometry was also performed to observe the materials’ impedance and stability. We report improved performance of hybridized catalyst for ORR based on cyclic voltammetry and EIS results, which show that it can be a potential candidate for fuel cell applications.

Freshwater sources are limited and access to clean water is an acute challenge in recent decades. The sustainable water treatments methods are need of time and water desalination is one of the most interesting technology. Most desalination technologies are required high energy input while Microbial Desalination Cells (MDCs) represent a sustainable option that has added benefit of solving the ever-increasing wastewater treatment and management problem. MDCs are a customized type of Microbial Fuel Cells (MFCs) that depend on the electric potential generated by organic media to decrease salt concentration by electro-dialysis and give an unconventional way of clean water production. In this research, various experiments were conducted to examine the desalination ability of an indigenously designed experimental setup using domestic wastewater inoculated with sewage sludge under identical conditions. The electrochemical properties of the system, comprising the polarization curve and Electrochemical Impedance Spectroscopy (EIS), were examined along with the scope of chemical oxygen demand (COD) exclusion, to distinguish the cell behaviour. Furthermore, acidic water and Phosphate Buffer Solution (PBS) were tested as potential catholytes compared to the performance of the wastewater was gauged at various salt concentrations. The maximum salt removal efficiency was 31%, power density and current density were 32 mW-m-2 and 246 mA-m-2 respectively at a salt concentration of 35 g-L-1 that decreases with a decline in salt concentration. The maximum achieved power density and current density were 32 mW-m-2 and 246 mA-m-2 respectively. The applied method has huge potential to scaleup for large scale application in coastal regions.

Abstract This paper provides a review about the major work done on helical baffles to improve the performance of shell and tube heat exchangers. Some of the major factors affecting the performance of shell and tube heat exchanger are discussed. A comparison between segmental baffles and helical baffles is also presented to show that helical baffles are more advantageous than segmental baffles. In most cases, discontinuous, folded, sextant helical baffles, 40° baffle inclination angle as well as low baffle spacing will give the best results when integrated in some combination, whereas continuous helical baffles eliminate dead regions. Moreover, sealing strips are more likely to improve the performance of shell and tube heat exchangers with continuous helical baffles.