Thermal analyses of minichannels and use of mathematical and numerical models

Growth in electronic devices comes with a challenge to engineers to provide proficient cooling mechanism in order to evade performance decline. Minichannel heat sinks are one among type of cooling devices to absorb heat formed in the electronic devices. Air is largely employed as cooling fluid in minichannels, but innovative methods are also adopted to enhance the heat transfer during the process. These days with modifications in the fluid flow passage and using liquid coolants such as nanofluids the Nusselt number is enhanced. These structural modifications adopted and different nanofluids employed with various volume concentrations and flow rates passed through minichannels to obtain enhancement in heat transfer rate are compiled in this article. The approach for these investigations is majorly categorized into numerical and experimental works. Numerical studies consisting of wide spread modeling methods like single phase/two phase flow modeling, laminar, transition/turbulent modeling etc. are reviewed. The related in-depth numerical and mathematical models used for computational analyses are detailed out exclusively. Experimental methods consisting of unusual passive techniques such as dimples/protrusions, pin fins, and corrugated channels. to achieve betterment in minichannel thermal performance are also provided. Another prime highlight of this article is compilation (in tabular form) of all the correlations and mathematical models used and developed to analyze different factors/properties during the thermal analyses. This article is concluded by providing an overall idea of different mathematical models and methods adopted in minichannels heat transfer analyses and future aspects to be addressed. Several important areas in minichannels heat transfer analyses exist which demand the optimization of heat and fluid flow processes and the use of machine learning concepts for analysis

Effect of Injection Parameters on the Performance of Compression Ignition Engine Powered with Jamun Seed and Cashew Nutshell B20 Biodiesel Blends

Renewable fuels are alternative resources that find use in the power generation, agricultural, and transportation sectors. The sustainable utility of these renewable fuels mostly addresses the socio-economic issues of a country and reduces its dependency on fossil fuels. In addition, being environmentally friendly allows them to handle global warming more effectively. Two B20 fuel blends were produced using methyl esters of cashew nutshell and jamun seed oils to test the performance of the common rail direct injection engine. To improve the engine performance, injection parameters such as nozzle geometry, injection time, and injector opening pressure are used. Improved brake thermal efficiency and lower emissions of smoke, hydrocarbons (HC), carbon monoxide (CO), and nitrogen oxides (NOx) were achieved with the help of advancing the injection timing, raising the injector opening pressure, and increasing the number of injector nozzle holes. In addition to reducing the ignition delay, extending the combustion duration, and increasing the peak pressure, the revised injection settings also boosted the heat release rates. At the maximum load, compared to CHNOB B20, JAMNSOB B20 showed a significant rise in the brake thermal efficiency (BTE) by 4.94% and a considerable decrease in smoke emissions (0.8%) with an increase in NOx (1.45%), by varying the injection timing, injection pressure, and nozzle geometry of the common rail direct injection (CRDI) engine

Comparative Analysis of Performance, Emission, and Combustion Characteristics of a Common Rail Direct Injection Diesel Engine Powered with Three Different Biodiesel Blends

Biodiesel is a renewable energy source which is gaining prominence as an alternative fuel over fossil diesel for different applications. Due to their higher viscosity and lower volatility, biodiesels are blended with diesel in various proportions. B20 blends are viable and sustainable solutions in diesel engines with acceptable engine performance as they can replace 20% fossil fuel usage. Biodiesel blends are slightly viscous as compared with diesel and can be used in common rail direct injection (CRDI) engines which provide high pressure injection using an electronic control unit (ECU) with fuel flexibility. In view of this, B20 blends of three biodiesels derived from cashew nutshell (CHNOB (B20)), jackfruit seed (JACKSOB (B20)), and Jamun seed (JAMNSOB (B20)) oils are used in a modified single-cylinder high-pressure-assisted CRDI diesel engine. At a BP of 5.2 kW, for JAMNSOB (B20) operation, BTE, NOx, and PP increased 4.04%, 0.56%, and 5.4%, respectively, and smoke, HC, CO, ID, and CD decreased 5.12%, 6.25%, 2.75%, 5.15%, and 6.25%, respectively, as compared with jackfruit B20 operation