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In recent years, composite materials such as carbon-fibre-reinforced plastic (CFRP) have been widely used in medical devices, industries, marine and aerospace applications due to their high resistance-to-weight ratio toughness, corrosion resistance, and other novel properties. The machining of these composite materials using conventional machines results in poor precision and surface finishing due to excess heat generation at the tool-material contact zone. The drawbacks of the conventional machining process can be overcome with the adoption of a novel cutting technique using pressurized water, which can dissipate the heat generated by the impact of abrasive particles against the material in order to eliminate the poor precision and surface finishing caused by overheating. In this experimental study, the performance of surface quality (roughness and kerf angle) of CFRP machining using an abrasive water jet technique has been studied for a wide range of cutting parameters, such as water pressure and cutting speed.

Adding varieties of nanoparticles to the base fluid is a recent technique for boosting the thermal performance of mono-nanofluids and conventional fluids. The main intension of this article is to investigate the forced convection heat transfer of water-based Al2O3 nanofluid and Al2O3 + graphene hybrid nanofluid numerically. Selected volume concentrations of Al2O3/water nanofluid (0.3, 0.6, and 1.0 vol%) has been compared with Al2O3 + graphene hybrid nanofluid. The working fluids were tested in three different sizes of mini tubes, i.e., 2.1, 1.1, and 0.8 mm. The homogeneous model was breezed to simulate the hybrid nanofluids. Thermophysical and rheological properties of the nanofluids were taken from standard experimental tests which are available in the literature to validate toward computational study. The results clearly indicate usage of Al2O3/water nanofluid greatly enhances convection heat transfer performance in mini tube. A high enhancement in heat transfer coefficient by adding 0.0175 vol% graphene nanosheets was performed in simulation, which provide a range between 12.7 and 13.7% over Al2O3/water nanofluids. However, the divergence of impact for adding graphene on Al2O3 nanofluids was marginal with change in mini tube sizes. Moreover, extra penalty in pressure drop was noted.

One of the popular ways to improve thermal efficiency of porous media burners is by enabling smart materials in reaction zone. In this experimental work, a predefined bilayer porous media micro burner was made to achieve both surface and submerged flame for a foam type (Alumina) of reaction layer and compared with conventional style of using discrete type. Moreover, preheat layer was also made up of foam (porcelain), which helped in attaining stable flame. This work mainly aimed to show burner behavior from rich to lean region at critical equivalence ratios. During surface mode combustion highest temperature was recorded for foam type was at equivalence ratio of 1.1, while discrete type was 1.3. Similarly, submerged mode combustion reordered maximum temperature for both foam and discrete type was around 0.6. Finally, thermal efficiencies where calculated at suitable equivalence ratios and emitted emission from the burner tip was also taken into considerations.

The applications of porous media burners are of massive interest to researchers from decades, and still trending in the modern world because of their tremendous advantages, such as high thermal efficiency and low emissions. In this work, a microburner was made to achieve surface and submerged flame region for different thicknesses of preheat layers. A reaction layer of alumina foam with a predefined thickness was used, whereas the preheat layer of porcelain foam was replaced with three different thicknesses namely 5, 10, and 15 mm. By using 5 mm preheat layer, only surface flame was visible with absolutely no trace of submerged flame region, while 10 and 15 mm can undergo both surface and submerged flame region. Equivalence ratio of 0.7 was observed to give best performance with regards to surface flame, while 0.5 for submerged flame region. Only 10 mm can able to give highest thermal efficiencies reaching 90% and 38% for the surface and submerged flame region respectively. Finally, low emission rate for NOx and CO was seen for all the possible individual cases.

Unsaturated polyester (UPE) composites filled with coconut shell (CS) powder was prepared by compression molding technique. To improve the mechanical and physical properties of CS-UPE composites, titanium dioxide (TiO2) filler was added. CS also undergo two types of chemical treatment which were alkaline (NaOH) and silane treatment. Fourier transform infrared (FTIR) was used to investigate the changes of fibers chemical constituents after the two chemical treatments have been done. CS-TiO2-UPE composites was characterized with physical testing (density, water absorption and thickness swelling), mechanical properties (tensile and flexural test) and scanning electron microscopy (SEM). Overall, the result shows that, the presence of CS and TiO2 filler in UPE composites demonstrated the highest density. For water absorption and thickness swelling study, it was observed that the treated CS-UPE composites showed lower water absorption properties in comparison to those of untreated CS-UPE composites. The presence of TiO2 filler showed an increased in those water absorption properties but still low compared to CS filled UPE. Both chemical treatment of CS caused a significant increase in the tensile and flexural properties. The presence of TiO2 filler demonstrated a significant improvement in modulus properties but at the expense of strength properties. SEM investigation has shown that the surface modification of CS has better fiber-matrix interaction. Thus, chemical treatments on the CS improve fiber/matrix adhesion of UPE composites.

Occurrence of combustion phenomenon in porous media has always excited researchers to develop various shape and size of burner so that maximum utilization of energy can be taken achieved. Here in this experiential work, dual layer micro burner was exclusively built to carry out porous media combustion characteristic with different type of discrete material in reaction zone. Presently, only alumina and zirconia are compared in discrete form, while preheat layer was made of porcelain ceramic material (foam type). Reaction zone was restricted to thickness of 20mm while preheat zone at 10mm. A concept of equivalence ratio was aided since it involves premixed combustion of air and butane as fuel mixture. Additionally, burner was made to run under lean to ultra-lean modes and finest temperature were recorded. Both surface and submerged flame was generated effectively. Maximum temperatures recorded during surface and submerged flame condition was better by installing alumina rather than zirconia there by reaching a value of 631°C and 470°C respectively. Thus maximum thermal efficiency was calculated and found out to be 84%. Finally, emission parameters like NOx and CO where monitored and found out to be well within acceptable limits.

The applications of porous media burners are of often keen interest to researchers because of many modern advantages, such as high thermal efficiency, stable flame and low emission rate. In this current experimental work, a microburner was made built to achieve both surface and submerged flame for three different thicknesses of reaction layers. A reaction layer of discrete alumina with a predefined thickness of preheat layer was used for combustion. Reaction layer was accordingly replaced with different thicknesses of 10mm, 20mm and 30mm. This work mainly aimed to show burner behavior with increase in thickness of reaction layer thus suggesting the optimum equivalence ratio from best burner performance. Interesting and unique behavior of the burner was encountered for each thickness of the reaction layer. Highest surface temperature was found out with 10mm of reaction layer, while highest wall temperature was incorporated with 20mm of reaction layer. Equivalence ratio of 0.3 is best suitable for optimum p...

Porous media combustion is considered to be one of the popular choice due to its tremendous advantages. Such type of combustion liberates not only super stable flame but also maintains emissions parameters below thresholds level. Present study incorporates reaction and preheat layer with discrete and foam type of materials respectively. Burner was made to run in ultra-lean mode. Optimum equivalence ratio was found out to be 0.7 for surface flame, while 0.6 during submerged flame condition. Maximum thermal efficiency was noted to be 81%. Finally, emissions parameters where recorded continuously to measure NOx and CO, which were under global limits.