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The mathematical modeling of the activation energy and binary chemical reaction system with six distinct types of nanoparticles, along with the magnetohydrodynamic effect, is studied in this paper. Different types of hybrid nanofluids flowing over porous surfaces with heat and mass transfer aspects are examined here. The empirical relations for nanoparticle materials associated with thermophysical properties are expressed as partial differential equations, which are then interpreted into ordinary differential expressions using appropriate variables. The initial shooting method converts the boundary condition into the initial condition with an appropriate guess and finally finds out an accurate numerical solution by using the Runge–Kutta method with numerical stability. Variations in nanoparticle volume fraction at the lower and upper walls of porous surfaces, as well as the heat transfer rate measurements, are computed using the controlling physical factors. The effects of the flow-related variables on the axial velocity, radial velocity, temperature, and concentration profile dispersion are also investigated. The Permeable Reynolds number is directly proportional to the regression parameter. The injection/suction phenomenon associated with the expanding/contracting cases, respectively, have been described with engineering parameters. The hybrid nanoparticle volume fraction (1–5%) has a significant effect on the thermal system and radial velocity.

The numerical analysis of MHD-free convective heat transfer and its interaction with the radiation over a heated flame inside a porous semicircular cavity loaded with SWCNTs–water nanofluid was explored for the very first time in the present work. The two circular arcs of the upper wall of the enclosure were preserved at a constant cold temperature, whereas the middle region of it was considered adiabatic. The midland region of the lower wall was heated partially, while other regions were also assumed adiabatic. An internal hot flame was included inside the cavity, while the cavity was exposed to a magnetic field. The results were illustrated for Hartmann number (0 ≤ Ha ≤ 100), Rayleigh number (104 ≤ Ra ≤ 106), heated region length (0.1 ≤ L ≤ 0.3), solid volumetric fraction (0 ≤ φ ≤ 0.04), Darcy number (10−3 ≤ Da ≤ 10−5) and radiation parameter (0 ≤ Rd ≤ 1). It was found that decreasing L is the best option for enhancing natural convection. Moreover, it was noted that (Nuout) is directly proportion to (Ra), (ϕ), (Rd) and (Da) increase. In contrast, it was in reverse proportion to (Ha). Furthermore, the results showed that augmentation of about (4%) and a decrement of (56.55%) are obtained on the average (Nu) on the heated length by increasing the radiation and the Hartmann number, respectively. Moreover, raising the radiation number from (0 to 1) causes an augmentation of about (73%) in the average (Nu) of the heated flame. Results also indicated that increasing the Hartmann number will cause a decrement of about (82.4%) of the maximum velocity profile in the vertical direction.

Purpose The purpose of the present work is to investigate the hydrodynamic and thermal performance of a thermal storage based on the numerical and experimental approaches using the lattice Boltzmann method and the experimental observation on the thermo-physical properties of the operating fluid. Design/methodology/approach For this purpose, the Al2O3 nanoparticle is added to the lubricant with four nanoparticle concentrations, including 0.1, 0.2, 0.4 and 0.6Vol.%. After preparing the nanolubricant samples, the thermal conductivity and dynamic viscosity of nanolubricant are measured using thermal analyzer and viscometer, respectively. Finally, the extracted data are used in the numerical simulation using provided correlations. In the numerical process, the lattice Boltzmann equations based on Bhatnagar–Gross Krook model are used. Also, some modifications are applied to treat with the complex boundary conditions. In addition, the second law analysis is used based on the local and total views. Findings Different types of results are reported, including the flow structure, temperature distribution, contours of local entropy generation, value of average Nusselt number, value of entropy generation and value of Bejan number. Originality/value The originality of this work is combining a modern numerical methodology with experimental data to simulate the convective flow for an industrial application.

In this study, a diesel engine was used to operate with blends of light fraction waste cooking oil (LFWCO) with diethyl ether (DEE). DEE was blended as an additive in the 5% to 20% ratio in steps of 5% each. The test indicates that LFWCO+15-DEE produced optimum results regarding performance and emission. The BSFC for LFWCO+15-DEE was found to be higher by about 28.9%, and the BTE was lower by about 7.6%, in contrast to diesel, at 100% operating load, respectively. For LFWCO+15-DEE the EGT was lower by about 11.9%, in contrast to neat diesel, at 100% operating load. The various emissions such as carbon monoxide (CO), nitrous oxide (NO), and smoke opacity for LFWCO+15-DEE were found to be lower by about 32.9%, 25%, and 29.4%, but the NO release was more than other blends and it was about 36%, in contrast to diesel at 100% operating load, respectively.

This numerical investigation effectively establishes a unique computing exploration for steady magnetohydrodynamic convective streams of tangent hyperbolic nanofluid traveling across a nonlinearly elongating elastic surface with a variable thickness. In addition, the importance of an externally imposed magnetic field of tangent hyperbolic nanofluid is comprehensively analyzed by considering the substantial impact of thermal conductivity and thermal radiation consequences. The governing PDEs (partial differential equations) are transmuted into a nonlinear differential structure of coupled ODEs (ordinary differential equations) using a series of variable similarity transformations. Furthermore, these generated ODEs (ordinary differential equations) are numerically set using a novel revolutionary Runge-Kutta algorithm with a shooting approach constructed in a MATLAB script. In this regard, extensive comparison studies are carried out to validate the acquired numerical results. The interactions between the associated profiles and the relevant parameters are rationally explored and shown using graphs and tabular forms. The velocity distribution declined with improving Weissengberg number We and power-law index m, while the reverse performance can be observed for temperature. As enhancement in Brownian motion, Thermophoretic and radiation parameters significantly rise in temperature distribution. The use of many different technological and industrial systems, including nano-bioconvective systems, nano-droplet evaporation, nano-ink jet printing, and microbial fuel cells, would benefit this research study.

This up-to-date and comprehensive literature study provides a rich overview of recent developments in several solar still types. This review examines a large number of theoretical, experimental, and computational studies connected to the single-slope, double-slope, solar still with a condenser, hybrid, and other limited types of solar stills. To make the work more relevant to readers, the authors provide a panoramic view of solar still varieties as well as a complete overview of the most recently published review papers in the solar stills field. The most important conclusions drawn from prior research are carefully discussed and outlined in a useful table to give interested researchers a good road map of many various sorts of solar stills and encourage them to pursue new research avenues in this field. The foremost key results of the evaluated work are presented in a table for readers’ convenience. The results indicated that the absorption in the basin was improved by adding charcoal, matt, sponge, jute and cotton clothes, dye, wick, porous or energy-storing material, black rubber, and floating absorber sheet. Moreover, the productivity of solar stills was significantly improved by using the inclined external flat-plate reflector, combined stills, condenser, sun tracking system, reflectors, greenhouse, hot water tank, solar collector, heat exchanger, and solar pond. Further, heat loss was minimized by re-utilizing the latent heat of condensation, cover cooling, and increasing the insulation thickness.

In this paper, forced convection of a multiwalled carbon nanotube (MWCNT)–water nanofluid (NF) in a new flat plate solar collector (FPSC) equipped with elliptical pipes instead of circular ones is investigated. The three-dimensional conservation equations were solved in the domain with the finite volume method (FVM) based on the semi-implicit method for pressure linked equations (SIMPLE) algorithm. The laminar-turbulent range of the Reynolds number (Re) and the volume fraction of the NF (ϕ) were 50–12,000 and 0–0.1, respectively. The optimization process was accomplished through the comparison of diverse parameters to attain the optimal case with the highest exergy efficiency. In this study, it was concluded that, in the case of using elliptical pipes instead of circular tubes, the time that the fluid was inside the FPSC increased, which led to an increase in the outlet temperature, while the exergy efficiency of the FPSC increased. Additionally, it was observed that using elliptical pipes enhanced the outlet fluid temperature, energy efficiency, and exergy efficiency. Generally, while the trend of exergy efficiency variation with effective parameters was rising, applying elliptical pipes caused the efficiency to increase. In addition, the exergy efficiency variation decreased when these parameters were changed. The highest value of exergy efficiency was 7.1%. On the other hand, for each specific FPSC, there was a unique mass flow rate at which the exergy efficiency reached its maximum value, and for higher mass flow rates, the efficiency was slightly diminished and then remained unchanged. Finally, the highest exergy efficiency was achieved for ϕ = 0.10%.

The use of nano additives to improve the cold properties of biodiesel is encouraged by its drawbacks and incompatibility in cold climate. Waste cooking oil (WCO) was transesterified to create biodiesel. A 20% by volume was used for combination of diesel and methyl ester. Current study aims to evaluate diesel engine emissions and performance. TiO 2 , alumina, and hybrid TiO 2  + Al 2 O 3 nanoparticles are added to WCO biodiesel mixture at 25 mg/liter. When B20 combined with nano materials such as TiO 2 , Al 2 O 3 , and hybrid nano, the highest declines in brake specific fuel consumption were 4, 6, and 11%, respectively. As compared to biodiesel blend, the largest gains in thermal efficiency were 4.5, 6.5, and 12.5%, respectively, at maximum engine output power. Introduction of TiO 2 , Al 2 O 3 , and hybrid nano particles to B20 at 100% load resulted in the highest decreases in HC concentrations up to 7, 13, and 20%, and the biggest reductions in CO emissions, up to 6, 12, and 16%. Largest increases in NOx concentrations at full load were about 7, 15, and 23% for B20 + 25TiO 2 , B20 + 25 Al 2 O 3 , and B20 + 25TiO 2  + 25 Al 2 O 3 , respectively. Up to 8, 15, and 21% less smoke was released, correspondingly, which were the largest reductions. Recommended dosage of 25 ppm alumina and 25 ppm TiO 2 achieved noticeable improvements in diesel engine performance, combustion and emissions about B20.

Purpose The purpose of this study is to address a problem in cooling of an electronic package where the dissipating fins transfer the extra heat energy from the heat source (i.e. electronic devices) to the heat sink (i.e. environment). To this end, the convective heat transfer of nanofluid flow over dissipating fins is simulated using a numerical approach, whereas the properties of nanofluid are evaluated based on the experimental measurements and used in the numerical process. Design/methodology/approach To simulate the convective flow, the lattice Boltzmann method is used. Also, the curved boundary scheme is used to enhance the capability of lattice Boltzmann method (LBM) in the simulation of natural convection in curved boundaries. In addition, the second law analysis is used based on total and local approaches. Findings To improve the cooling performance of fins, a modern technique is used, which is using of nanofluid. For this purpose, samples of SiO2-liquid paraffin with mass fractions of 0.01, 0.05, 0.1, 0.5 and 1 (Wt.%) in a temperature range of 25–60 °C are provided, and the required thermal and physical properties of samples including thermal conductivity and dynamic viscosity are measured during experimental work. The extracted results are used in the numerical simulations using derived correlations. Originality/value The originality of the present work is using a modern numerical method in the investigation of an engineering application and combining it with experimental data.

Many strategies have been attempted for accomplishing the needed changes in the heat-transfer rate in closed cavities in recent years. Some strategies used include the addition of flexible or hard partitions to the cavities (to split them into various pieces), thickening the borders, providing fins to the cavities, or altering the forms or cavity angles. Each of these methods may be used to increase or decrease heat transmission. Many computational and experimental investigations of heat transport in various cavity shapes have been conducted. The majority of studies focused on improving the thermal efficiency of heat transmission in various cavity containers. This paper introduced a review of experimental, numerical, and analytical studies related to heat transfer analyses in different geometries, such as circular, cylindrical, hexagonal, and rectangular cavities. Results of the evaluated studies indicate that the fin design increased heat transmission and sped up the melting time of the PCM; the optimal wind incidence angle for the maximum loss of combined convective heat depends on the tilt angle of the cavity and wind speed. The Nusselt number graphs behave differently when decreasing the Richardson number. Comparatively, the natural heat transfer process dominates at Ri = 10, but lid motion is absent at Ri = 1. For a given Ri and Pr, the cavity without a block performed better than the cavity with a square or circular block. The heat transfer coefficient at the heating sources has been established as a performance indicator. Hot source fins improve heat transmission and reduce gallium melting time.