Geoelectric Investigation of Aquifer Vulnerability within Afe Babalola University, Ado –Ekiti, Southwestern Nigeria.

Many investigation techniques are commonly employed with the aim of estimating the spatial distribution of transmissivity and protective capacity of groundwater resources. Unfortunately, the conventional methods for the determination of hydraulic parameters such as pumping tests, permeameter measurements and grain size analysis are intrusive and relatively expensive. A non-intrusive and less-expensive geoelectric investigation involving vertical electrical sounding was carried out in some parts of the campus of Afe Babalola University, Ado Ekiti, Ekiti State, Nigeria. A total of fifty-nine (59) vertical electrical sounding (VES) data were acquired using R 50 D.C. resistivity meter within the campus which is underlain by the Precambrian basement rock of southwestern Nigeria. Following the interpretation of the VES data, maps and 2D-sections were generated. The geoelectric sections enabled the subsurface to be characterized into five geoelectric layers namely: Topsoil, clayey/sandy-clay, weathered layer, fractured basement and fresh basement. The assessment and analysis of the materials above the aquifers showed that longitudinal conductance (S) values ranged from 0.08438 to 0.73449 mhos; thus the area is classified into weak (0.1 – 0.19 mhos), moderate (0.2 – 0.69 mhos) and good protective capacity (0.7 mhos and above). The major aquifer delineated is the weathered/fractured basement aquifers. These aquifers are characterized by thick overburden, moderate/good protective capacity, moderate to relatively high value coefficients of anisotropy and low transverse unit resistance. This suggests that the materials above the aquifers act as seal, thus protecting the major aquiferous units. However, the aquifer matrix itself is relatively permeable. Areas with weak protective capacity are therefore vulnerable to infiltration of polluting fluid

Energy efficiency improvements by investigating the water flooding management on proton exchange membrane fuel cell (PEMFC)

This paper presents a broad study of research work associated with the effect of water flooding and management in Proton Exchange Membrane Fuel Cells (PEMFC) which operates at relatively low temperatures at conditions that could allow the accumulation of water that degrade cell performance. Recent studies confirm the importance of proper water balance during cell operation to avoid both dehydration and flooding. Condition to ensure the PEM remains hydrated while excessive water condensation is prevented are identified and analysed. The work review current literature and examines the different mechanisms of water transport in PEMFCs and their relative importance and impact on cell operation. The work analyse the effect of water accumulation at both the anode and the cathode regions and discusses the impact on cell efficiency of each. This work reviews recent development in this field and examines the approaches used such as improved flow field designs, improved membrane chemical formulation to increase hydrophilicity, manipulation of operating pressure, optimisation of operating temperature, the level of humidification, optimisation of gas flow rate and mechanical modification of the membrane structure among other techniques. The work examines recent advances in the techniques for non-intrusive in-situ water detection, monitoring and characterisation and compares their effectiveness. The work concludes by a critical review of recent studies that examined different strategies that could prevent water flooding and promote proper water management in PEM fuel cells. This includes water management control strategies designed to improve the voltage and current density at specific operating conditions