Analysis of Fluid Flow and Heat Transfer in Corrugated Perforated Plate Fin Heat Sinks

This paper reports a mathematical model for predicting the fluid and heat flow characteristics of a Z-shaped corrugated perforated plate heat sink. Experiments were carried out to validate overall pressure drop as well as heat transfer predictions. A two-pronged approach was undertaken to design a corrugated perforated fin geometry: (a) macroscopic packaging, where the flow is distributed into conduits before being fed into perforated plates, and (b) microscopic design, where the pores are sized to maximize heat dissipation. A methodology typically used for predicting flow maldistribution is extended for packaging porous perforated plates in the macroscopic approach. An illustrative study is carried that estimates the optimum number of porous perforated plate fins that can be packaged within a given volume under fixed pressure drop constraint. In the microscopic approach, an order of magnitude analysis was carried out to decide the optimum diameter to maximize the heat transfer rate and expression for optimum diameter, and maximum achievable heat flux is proposed. Numerical simulations were carried out by considering full perforated plate porous fin geometry and single-channel geometry, and good agreement in their results was found. Finally, this study elaborates on the importance of achieving uniform flow distribution across the porous perforated plate fins.

Optimization of pipeline lifecycle cost using alternatives with different life spans

This paper suggests a pipeline project optimization approach that compares alternatives with different life spans. The average inflation rate is used to project the future maintenance, operation and replacement costs. The average interest rate is used to express all the costs in Equivalent Real Annual Cost (ERAC), which is the correct cost form to compare alternatives with different life spans. The pipe diameter, material, pressure rating, surge tank size, and inlet/outlet resistances are the decision variables. A software was compiled with a commercial pipeline software to generate all the possible design alternatives based on the decision variables. Pipe initial cost as well as operation and maintenance costs are computed for each design alternative. The alternative with the least ERAC value is the optimum one. It was found that the approach can lead to substantial savings in pipelines projects cost. For pipes 800 mm in diameter or larger, and when selecting the optimum diameter, savings are between 23 and 27% in the total project cost. When imposing certain pipe material savings in overall cost will be 8.5, 16.3 and 31.3% for ductile iron, GRP and mild steel pipe material, respectively.

Explicit dynamics based numerical simulation approach for assessment of impact of relief hole on blast induced deformation pattern in an underground face blast

The breakage of rock mass by blasting has many challenges. The optimal breakage in an underground development face/tunnel blast is dominantly dependent on the relief area provided to the blast holes. The cut portion in the burn cut face blast is significantly important to achieve the controlled deformation due to the blast. This paper has discussed the impact of the number and diameter of the relief holes on the breakage pattern of the rock. The numerical simulation with varying numbers and diameter of relief hole was carried out for this purpose. Finite element modeller explicit dynamics of Ansys-Autodyn was used for the simulation work. The isosurface of non-deformed zone was plotted to compare the extent of deformation under varying conditions of relief holes. The analysis shows that the higher number of relief holes with optimum diameter gives more controlled deformation than single relief hole with larger diameter. The nearfield vibration was also recorded by placement of seismograph. The waveform analysis of the recorded vibration was carried out. The redesigning of the blasting pattern was done using the results of numerical simulation and waveform analysis. The redesigned pattern consists of four relief holes of 115 mm diameter. The blasting output with the revised design has resulted into the considerable improvements in the pull and reduction of overbreak. The revised pattern has addressed the issue of the socket formation at the site.

An Insight into Biofunctional Curcumin/Gelatin Nanofibers

Electrospinning (ESPNG) was used to synthesize ultrathin (UT) and uniform nanofibers (from 5 nm to a few hundred nanometers) of various materials which have biomedical applications (BAs) such as dressing of wounds, drug discharge, and so on and so forth. In the first half of the report, there is an audit on the nanofibers having low diameter so that it could have larger surface area to volume proportion, likewise with that it would have sufficient porosity and improved mechanical properties required for wound healing. Nanofibrous mats (NMs) with high biocompatibility could be utilized during healing of wounds by sustained release of curcumin (Cc) and oxygen. The ESPNG was understood through in-depth numerical investigation in the present report. Furthermore, the process parameters (PMs) were reviewed in depth for their contributions in synthesizing UT - Curcumin/Gelatin (Cc/G) nanofibers (NFs) of optimum diameter. The aim of the discussion was to demonstrate that simply optimizing biofunctional (BF) - Cc/G NFs might not be enough to satisfy experts until they are also given access details about the complete ESPNG method (mathematical mechanism) to improve hold over the synthesis of NMs (suitable for BAs) for the release profile of Cc throughout critical periods of healing process.

On the Selection of Optimal Propeller Diameter for a 120-m Cargo Vessel

In the preliminary design of a propulsion unit, the selection of propeller diameter is most commonly based on open water tests of systematic propeller series. The optimum diameter obtained from the propeller series data is, however, not considered to be representative for the operating conditions behind the ship, instead a slightly smaller diameter is often selected. We have used computational fluid dynamics to study a 120-m cargo vessel with an integrated rudder bulb-propeller hubcap system and a four-bladed propeller series, to increase our understanding of the hydrodynamic effects influencing the optimum. The results indicate that a 3-4% smaller diameter is optimal in behind conditions in relation to open water conditions at the same scale factor. The reason is that smaller, higher loaded propellers perform better together with a rudder system. This requires that the gain in transverse kinetic energy losses thanks to the rudder overcomes the increase in viscous losses in the complete propulsion system.

Optimum diameter for laser beam and effect of temperature rise on the optical bistability hysteresis loops

In this research, analytical study for simulating a Fabry-Perot bistable etalon (F-P cavity) filled with a dispersive optimized nonlinear optical material (Kerr type) such as semiconductors Indium Antimonide (InSb). An optimization procedure using reflective (~85%) InSb etalon (~50µm) thick is described. For this etalon with a (50 µm) spot diameter beam, the minimum switching power is (~0.078 mW) and switching time is (~150 ns), leading to a switching energy of (~11.77 pJ) for this device. Also, the main role played by the temperature to change the etalon characteristic from nonlinear to linear dynamics.

Head Loss in Thin-Walled Drip Tapes with Continuous Labyrinth

Thin-walled drip tapes with continuous labyrinth have been used for irrigation of vegetables and other short-cycle crops, especially due to their low cost. The continuous labyrinths welded into the pipe inner wall affect the head loss along such emitting pipes. In addition, the flow cross section of thin-walled pipes may change due to the effects of the operating pressure, which also has consequences for the head loss. The objective of this work was to investigate experimentally the friction factor and the head loss on thin-walled drip tapes with continuous labyrinths operated under various pressures. Two models of commercial thin-walled drip tapes with continuous labyrinths were evaluated. Nonperforated samples were used to determine the head-loss equations. The equations were adjusted as a function of flow rate and pressure head at the pipe inlet. Alternatively, the diameter in the Darcy–Weisbach equation was adjusted as a function of the pressure head by a power-law model. The possibility of using a mean diameter in the Darcy–Weisbach equation was also analyzed. Experimental investigation indicated that the friction factor in the Darcy–Weisbach equation can be accurately described using a power-law model, like the Blasius equation, but characterized by a coefficient a=0.3442 for the Turbo Tape and a=0.3225 for the Silver Tape. The obtained values of a are larger than those generally used and available in the literature. The influence of the operating pressure on the pipe diameter can be neglected for the purpose of calculating the head loss. The two approaches, considering the variation of the diameter with the pressure head and considering an optimum average diameter for the calculation of head loss by the Darcy–Weisbach equation, produce similar results, allowing accurate prediction of head loss. Evaluating the proposed mathematical models, 95% of predictions presented relative errors of head loss smaller than 5%. For the Turbo Tape, the optimum diameter for the purpose of calculating the head loss is 16.01 mm, which is very close to the value indicated by its manufacturer (15.9 mm). For the Silver Drip, the optimum diameter is 15.71 mm, while the manufacturer gives a value of 16.22 mm, which produces considerable error in the calculation of head loss.