Energetic and exergetic investigations of an innovative light-based hydrogen production reactor

In this study, it is aimed to thermodynamically study and experimentally test a continuous type hybrid photoelectrochemical hydrogen production system. The hybrid system considered in this study is capable of enhancing solar spectrum utilization via the combination of photocatalysis and PV/T. In addition, the system eliminates the electron donor requirement of photocatalysis by employing photoelectrodes. Which, as a result, risk of potentially harmful pollutant emissions is reduced. In this study, the present system is investigated in electrolysis operation under three different inlet mass flow rates (0.25, 0.50, and 0.75 g/s). The experimental results are compared to the thermodynamic model outputs. Parametric studies are conducted by changing the inlet mass flow rate from 0 to 1 g/s. The present experimental results suggest that the highest hydrogen production rate is observed at 0.75 g/s inlet mass flow rate, which is 2.43 mg/h. The highest energy and exergy efficiencies are calculated at 0.25 g/s, which are 36% and 32%, respectively. Furthermore, thermodynamic model outputs are confirmed to have a good agreement with the experimental results.     

Tensile properties and fracture characteristics of ECAP-processed Al and Al-Cu alloys

In the present paper, billets of pure Al, and cast-homogenized Al-2 wt.%, 3 wt.%, and 5 wt.% Cu alloys were successfully processed by equal channel angular pressing (ECAP) up to 10 passes without fracture at room temperature using a die with a channel angle of 110°. Giant strains imposed on workpieces lead to extreme dislocation densities, microstructural refinement, and finally ultrafine grained materials. Tensile tests were employed to examine the fracture modes and fracture surface morphologies of the ECAP-processed Al and Al-Cu alloy samples. In particular, the effects of the number of ECAP passes and the Cu content were investigated.     

Adsorption characteristics and heat of adsorption measurements of R-134a on activated carbon

This paper presents adsorption isotherms of R-134a (HFC-134a) on highly porous pitch based activated carbon (Maxsorb III) in the temperature range of 5–70 °C and pressures up to 12 bar, using desorption method. The experimental data have been fitted with the Dubinin–Astakhov (D–A) isotherm equation. The adsorption isotherms of R-134a on Maxsorb III obtained from the present study are compared with the adsorption isotherm results of R-134a on similar type of adsorbents obtained by other researchers and they are found to be fairly consistent. The isosteric heat of adsorption of the assorted adsorbent–refrigerant pair has also been extracted from the present experimental data.     

Patent analysis of wind energy technology using the patent alert system

Using publicly available information effectively is important to remain competitive in technology related industries. The main difficulty in this is determining how to use the information effectively and in a manner that will yield results that can be acted upon. Several different methodologies are being developed in the Technology Watch area of research including the Patent Alert System (PAS) by Dereli and Durmusoglu. By using two different variations of the Patent Alert System, this paper will analyze two different technologies based on wind energy. These variations include Linear Regression based PAS and Fuzzy Logic based PAS. Each approach uses a different methodology to evaluate the available data and generate a trend that will be used to predict future values of patent counts in the applied area of technology. The results of these different approaches are compared in order to determine if either method produces more reliable results which would then lead to better decisions by the organization. In order to connect the results with real-world events, trend changes will be evaluated against global events which should have an impact on technological development in this area.     

Experimental study on machinability improvement of hardened tool steel using two dimensional vibration-assisted micro-end-milling

High strength, low thermal conductivity and high work hardening tendency of tool steel are the main factors that make its machinability difficult. In this paper, two dimensional vibration-assisted micro-end-milling (2-D VAMEM) is applied to machine the hardened tool steel (HRC 55 and HRC 58) in order to improve its machinability. The experiments are carried out to study the effects of vibration parameters on the surface roughness and the tool wear. It is found that 2-D VAMEM can improve the surface roughness and reduce the tool wear compared to traditional micro-end-milling, and larger amplitude and higher frequency are useful for the surface roughness improvement and the tool wear reduction. Therefore, 2-D VAMEM is an effective method to milling of hardened tool steel and can be applied in the manufacture of moulds and dies with improved machining efficiency, surface quality and tool life.