Green H2 Production by Water Electrolysis Using Cation Exchange Membrane: Insights on Activation and Ohmic Polarization Phenomena

Low-temperature electrolysis by using polymer electrolyte membranes (PEM) can play an important role in hydrogen energy transition. This work presents a study on the performance of a proton exchange membrane in the water electrolysis process at room temperature and atmospheric pressure. In the perspective of applications that need a device with small volume and low weight, a miniaturized electrolysis cell with a 36 cm2 active area of PEM over a total surface area of 76 cm2 of the device was used. H2 and O2 production rates, electrical power, energy efficiency, Faradaic efficiency and polarization curves were determined for all experiments. The effects of different parameters such as clamping pressure and materials of the electrodes on polarization phenomena were studied. The PEM used was a catalyst-coated membrane (Ir-Pt-Nafion™ 117 CCM). The maximum H2 production was about 0.02 g min−1 with a current density of 1.1 A cm−2 and a current power about 280 W. Clamping pressure and the type of electrode materials strongly influence the activation and ohmic polarization phenomena. High clamping pressure and electrodes in titanium compared to carbon electrodes improve the cell performance, and this results in lower ohmic and activation resistances.

Reduction of hole misalignment in turbocharger center housing

PurposeThis research work focuses on implementing this methodology in reducing the rejection rate of the turbocharger component problem that occurs during the manufacturing process. Using design, measure, analyze, improve and control (DMAIC) processes, it has been identified that clamping pressure on the component is one factor that affects quality. The impact of clamping pressure is studied to arrive at the ideal clamping pressure in which the rejection rate is the least.Design/methodology/approachQuality is the keyword in manufacturing where the production of a defect-free component is the most sought out objective. The definition of quality keeps getting refined throughout the years, from making products with no defects to minimizing rejection and scrap in the manufacturing process. Production facilities, to achieve this purpose, have adopted various methods and use of the DMAIC of Six Sigma methodology is one among them.FindingsThe study identified the fault causing the defect and suggested the methods to correct the fault. The suggestions would result in reducing the losses arising due to this and similar rejection causes.Originality/valueWith the adoption of DMAIC, it is found that misalignment of top and side clamp pressure is zero. When the side clamp pressure is at 75 PSI, and top clamp pressure is changed from 90 PSI to 95 PSI, the mean of responses is greater than the side clamp pressure of 80 PSI. Therefore, from the three-combination top clamp pressure of 100 PSI and the side clamp pressure of 75 PSI is the optimal condition.

Comparative Analysis of Circular and Square End Plates for a Highly Pressurized Proton Exchange Membrane Water Electrolysis Stack

End plates are located at both ends of a proton exchange membrane water electrolysis (PEMWE) stack. If the end plates are thin, clamping pressure is not uniform and the performance of PEMWE can deteriorate from leakage and high electrical contact resistance caused by the deformation of the thin end plates. In this study, end plates were designed to reduce the weight while clamping the stack uniformly by finite element analysis (FEA). The weights of the circular and square end plates were reduced compared to conventional end plates by 22.9% and 23.3%, respectively. The stress and strain distribution of square and circular end plates are analyzed using topology optimization. This analysis can improve the performance of the PEMWE by using new end plate designs verified by dummy cell stack simulation to maintain uniform pressure.

Experimental Study on a Thermoelectric Generator for Industrial Waste Heat Recovery Based on a Hexagonal Heat Exchanger

To study on the thermoelectric power generation for industrial waste heat recovery applied in a hot-air blower, an experimental thermoelectric generator (TEG) bench with the hexagonal heat exchanger and commercially available Bi2Te3 thermoelectric modules (TEMs) was established, and its performance was analyzed. The influences of several important influencing factors such as heat exchanger material, inlet gas temperature, backpressure, coolant temperature, clamping pressure and external load current on the output power and voltage of the TEG were comparatively tested. Experimental results show that the heat exchanger material, inlet gas temperature, clamping pressure and hot gas backpressure significantly affect the temperature distribution of the hexagonal heat exchanger, the brass hexagonal heat exchanger with lower backpressure and coolant temperature using ice water mixture enhance the temperature difference of TEMs and the overall output performance of TEG. Furthermore, compared with the flat-plate heat exchanger, the designed hexagonal heat exchanger has obvious advantages in temperature uniformity and low backpressure. When the maximum inlet gas temperature is 360 °C, the maximum hot side temperature of TEMs is 269.2 °C, the maximum clamping pressure of TEMs is 360 kg/m2, the generated maximum output power of TEG is approximately 11.5 W and the corresponding system efficiency is close to 1.0%. The meaningful results provide a good guide for the system optimization of low backpressure and temperature-uniform TEG, and especially demonstrate the promising potential of using brass hexagonal heat exchanger in the automotive exhaust heat recovery without degrading the original performance of internal combustion engine.