Effect of injection timing and injection duration of manifold injected fuels in reactivity controlled compression ignition engine operated with renewable fuels

In the current work, an effort is made to study the influence of injection timing (IT) and injection duration (ID) of manifold injected fuels (MIF) in the reactivity controlled compression ignition (RCCI) engine. Compressed natural gas (CNG) and compressed biogas (CBG) are used as the MIF along with diesel and blends of Thevetia Peruviana methyl ester (TPME) are used as the direct injected fuels (DIF). The ITs of the MIF that were studied includes 45°ATDC, 50°ATDC, and 55°ATDC. Also, present study includes impact of various IDs of the MIF such as 3, 6, and 9 ms on RCCI mode of combustion. The complete experimental work is conducted at 75% of rated power. The results show that among the different ITs studied, the D+CNG mixture exhibits higher brake thermal efficiency (BTE), about 29.32% is observed at 50° ATDC IT, which is about 1.77, 3.58, 5.56, 7.51, and 8.54% higher than D+CBG, B20+CNG, B20+CBG, B100+CNG, and B100+CBG fuel combinations. The highest BTE, about 30.25%, is found for the D+CNG fuel combination at 6 ms ID, which is about 1.69, 3.48, 5.32%, 7.24, and 9.16% higher as compared with the D+CBG, B20+CNG, B20+CBG, B100+CNG, and B100+CBG fuel combinations. At all ITs and IDs, higher emissions of nitric oxide (NOx) along with lower emissions of smoke, carbon monoxide (CO), and hydrocarbon (HC) are found for D+CNG mixture as related to other fuel mixtures. At all ITs and IDs, D+CNG gives higher In-cylinder pressure (ICP) and heat release rate (HRR) as compared with other fuel combinations

Investigation of flexural properties of epoxy composite by utilizing graphene nanofillers and natural hemp fibre reinforcement

This study aims to determine the optimum reinforcement required to attain the best combination of flexural strength of modified green composites (graphene oxide + hemp fibre reinforced epoxy composites) for potential use in structural applications. An attempt was also made for the combination of graphene and hemp fibres to enhance load-bearing ability. The infusion of hemp and graphene was made by the weight of the base matrix (epoxy composite). Results showed that graphene reinforcement at 0.4 wt.% of matrix showed load-sustaining capacity of 0.76 kN or 760 MPa. In the case of hemp fibre reinforcement at 0.2 wt.% of the matrix, infusion showed enhanced load-bearing ability (0.79 kN or 790 MPa). However, the combination of graphene (0.1 wt.% graphene nanofillers) and hemp (5 wt.% hemp fibre) indicated a load-sustaining ability of 0.425 kN or 425 MPa, whereas maximum deflection was observed for specimen with hemp 7.5 % + graphene 0.2 % with 1.9 mm. Graphene addition to the modified composites in combination with natural fibres showed promising results in enhancing the mechanical properties under study. Moreover, graphene-modified composites exhibited higher thermal resistance compared to natural fibre reinforced composites. However, when nanofiller reinforcement exceeded a threshold value, the composites exhibited reduced flexural strength as a result of nanofiller agglomeration

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

The effects of graphene oxide nanoparticle additive stably dispersed in dairy scum oil biodiesel-diesel fuel blend on CI engine: performance, emission and combustion characteristics

In the present investigation, the effects of graphene oxide nanoparticles on performance and emissions of a CI engine fueled with dairy scum oil biodiesel was studied. Nanofuel blend was prepared by dispersing graphene oxide in varying quantities in dairy scum oil methyl ester (DSOME)-diesel blend. Sodium dodecyl sulfate (SDS) was used as a surfactant for a steady dispersion of graphene oxide nanoparticles in the fuel blends. The dispersion and homogeneity were characterized by ultraviolet–visible spectrometry. An ideal graphene-to-surfactant ratio was defined, highest absolute value UV-absorbency was seen for a mass fraction of 1:4. The concentration of surfactant above or below this ratio resulted in reduction in the stability of dispersion. Graphene oxide nanoparticles were amalgamated with dairy scum oil biodiesel at proportions of 20, 40 and 60 parts per million using ultrasonication technique. Experiments were performed at a constant speed and varying the brake power and load condtions. The results were notable enhancements in the performance and emissions characteristics, the brake thermal efficiency improved by 11.56%, a reduction in brake specific fuel consumption by 8.34%, unburnt hydrocarbon by 21.68%, smoke by 24.88%, carbon monoxide by 38.662% for the nanofuel blend DSOME2040 and oxides of nitrogen emission by 5.62% for fuel DSOME(B20). Similarly, the addition of graphene nanoparticles in DSOME fuel blends resulted in significant reduction in the combustion duration, ignition delay period, improvement in the peak pressure and heat release rate at maximum load condition. Finally, it is concluded that nano-graphene oxide nanoparticles can be introduced as a suitable substitute fuel additive for dairy scum oil biodiesel blends to enhance the overall engine performance and emissions characteristics