The authors have considered a Double Pipe Heat Exchanger (DPHE) and various insert configurations of turbulators-Inner Side Triangular Ribs (ISTR) on both outer and inner pipe of DPHE, a helical spring on outer side of inner pipe of DPHE, and combined ISTR (inner) and helical spring wrapped over inner pipe. The study suggests that the turbulators inserted inside heat exchanger increase the Nusselt number by about 1.7 times for the triangular rib arrangements and about 1.3 times for spring arrangement over the tube without turbulator. The friction factor is found to be higher in case of ISTR on inner and outer pipe as compared to other arrangement due to higher blockage area which deflects the flow. At similar operating conditions, due to the improved turbulence and enhanced swirl flows, various arrangements of triangular ribs and helical springs as inserts in DPHE perform better in heat enhancement.

Small wind turbines of the 8-100 kW range serve as good sources of small-scale economically independent energy for agricultural and industrial consumers. Recent evidences point out that many small turbines are underperforming in the field compared to theoretical projections due to manufacturing defects and the aerodynamic design of the airfoil. In the paper, "Understanding the Performance Degradation of Small Stall-Regulated Wind Turbines Due to Typical Manufacturing Defects", the authors, Amool Raina, Kyle Wetzel and Saeed Farokhi, have presented the results of aerodynamic investigation of the wind turbine airfoils using Computational Fluid Dynamics (CFD). The authors have focused on the simulated effect of typical manufacturing on the performance of airfoils and on the effects due to critical Reynolds number range on these airfoils. The simulation results suggest that manufacturing flaws at the leading edge and camber distribution might have led to severe performance degradation, and also that the transitional Reynolds number range of 100k-300k may create multiple laminar separation bubbles that limit the aerodynamic performance of the airfoil sections.

Welding is a process of joining two similar or dissimilar metals by fusion, with or without the application of pressure, and a filler metal may be used if required. Gas Tungsten Arc Welding (GTAW) or Tungsten Inert Gas (TIG) welding is an arc welding process that employs a tungsten (nonconsumable) electrode to produce the weld. Shielding gas (usually an inert gas) is used to protect the weld zone from atmospheric gases. Thin sections of stainless steel and nonferrous metals such as aluminum, magnesium and copper alloys are generally welded by TIG welding. In the paper, "Optimization of TIG Welding Process Parameters for Ductility and Strength of Weld Bead Formed Between Aluminum Alloys Al 6061 and Al 5052", the authors, D Bahar, K Vittal Goud, K Sengameshwar and A Naresh, have carried out experiments by applying Taguchi Technique and gray relational analysis in order to optimize the percentage elongation and Ultimate Tensile Strength (UTS) of weld bead between aluminium alloys Al 6061 and Al 5052 specimen welded by TIG welding. The authors have proposed that welding current should be as high as 190 A, root gap should be medium around 2 mm and welding speed of around 120 mm/min, as well as low gas flow rate of 19 mm3/min to optimize the percentage elongation (ductility) and UTS.

Air-cooled engines are the only option for two-wheelers due to some advantages like lighter weight and lesser space requirement. An air-cooled engine releases heat into the atmosphere by means of forced convection by providing fins on the outer surface of the cylinder. The 250cc engine cylinder is one of the major automobile components subjected to high temperature variations and thermal stresses. In the paper, "Design and Thermal Analysis of 250cc Engine Cylinder Fin Using Different Material on Ansys Software: A Review", the authors, K R Gawande and Sameer Mahamandre, have reviewed various aspects of the design consideration of 250cc engine. The parameters considered in their review include various types of fins and cooling systems.