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An Earth-Air Heat Exchanger (EAHE) is a device that consists of one or more buried ducts through which air is forced to flow. The surrounding soil is responsible for enabling thermal exchanges along with the installation, making the temperature at the outlet milder than the inlet. The objective of this work is to ally a numerical-analytical approach with the Constructal Design method and Exhaustive Search technique to minimize the soil volume occupation (V), minimize the air flow pressure drop (PD), and maximize the thermal potential (TP) of a T-shaped EAHE. Starting from a conventional EAHE composed of a straight duct, called Reference Installation (RI), two degrees of freedom (DOF) were considered: the ratio between the length of the bifurcated branch and the length of the main branch (L1/L0) and the ratio between the diameter of the bifurcated branch and the diameter of the main branch (D1/D0). Comparing with RI, different T-shaped EAHE geometries were identified to reduce V by 23% and PD by 62% and to increase TP by 21%; and when these three performance parameters were concomitantly considered another T-shaped EAHE geometric configuration allowed to reach an improvement of around 27% when compared with the RI.

A spectral-based computational algorithm is presented, showing the effects of rotation and curvature on a fluid flow with natural and forced convective heat transfer (CHT) in a rotating curved rectangular channel with an aspect ratio of 3 and curvature ratio ranging from 0.001 to 0.5. The bottom wall of the channel is heated, with cooling from the ceiling; the vertical walls are thermally insulated. The system is rotated about the vertical axis in the positive and negative directions with the Taylor number $$-2500\le Tr \le 2500$$ due to a constant pressure gradient force applied in the stream-wise direction. With the numerical computation presented, five branches of asymmetric steady solution curves comprising single-pair to 11-pair vortices are found. The change in the flow state is then evaluated by means of time-evolution computation, and sketching of the phase space of the solutions enables good prediction of the flow transition. It is found that in the case of co-rotation, a chaotic flow turns into a steady-state flow via a periodic or multi-periodic flow. In the counter-rotation case, however, irregular oscillations change directly to a multi-periodic flow. The study shows appearance of maximum 6-pair vortices at a small curvature, 11-pair vortices at a moderate curvature, and maximum 2-pair vortices at strong curvature. It is also observed that the number of secondary vortices reduces as Tr increases. The vortex structure of secondary flows is also shown in bar diagrams for easy visualization of the effect of curvature on the flow evolution. The study shows that the CHT is significantly enhanced by the secondary flow and a chaotic flow boosts the heat transfer more effectively than other physically realizable solutions. Finally, a comparison between the simulated and experimental results is performed and reasonable matching between the two solutions is observed.

In the current study, this way was adopted numerically in order to optimize the performance of a HEC through the use of extended solid sections in the form of 'W' (W-baffles: WBs). All limit conditions of the channel have been defined, with all the thermo-physical properties of the HTF (heat transfer fluid) used. The FVM (Finite-Volume-Method) has been adopted with some necessary numerical schemes in order to give the numerical solution, which allows us to visualize dynamically the flow filed and to deduce all the energetic characteristics contained by this HE. Dynamically, the HTF flow velocity at the HEC outlet section reached about 1.812 m/s, in the case of the lowest Re value. While, it passed 4.8 m/s in the case of the largest value of the same variable, i.e. 1.726 to 4.648 times better than the Uin within the limits of Re numbers used. Thermally, areas with very hight TGs (temperature gradients) were observed near the top deflector’s sides, which reflects the effect of the W-baffles. This highlights the importance of the adopted obstacles in changing characteristics of the HEC to the best.

With increasing demand for electric energy and requesting higher quality by subscribers, the electric power industry has moved towards using new technologies. Many modern societies seek to use the systems of new energy management in order to reduce environmental pollutants and operational costs in electrical energy systems. Therefore, exploiting various resources of renewable energies, micro-grids can be considered as a significant tool to attain these objectives. According to the subject, Ant Colony Optimization algorithm (ACO) is used in this paper to optimize one micro-grid sample in order to reduce the cost of generating power and to reduce environmental pollution to increase reliability. The recommended algorithm has been done in two scenarios and each in two sections. In the first scenario, energy management will be conducted for all distributed generation resources and in the second scenario it is assumed that wind and solar products, produce their maximum power and energy management are conducted for the reminder elements and the results are compared with other optimization algorithms.

In this paper, the MOPSO algorithm has been used to locate and determine the capacity of distributed generation sources and capacitor banks in the distribution system. The intended objective function is a combination of different objective functions. The first goal is to reduce losses, and the second goal is to improve the voltage profile and the third goal is to reduce costs, which has been used by placing weight coefficients in the form of an objective function in the algorithms. For this purpose, the standard 33-bus system has been used to conduct studies. Studies have been repeated in three scenarios. In the first scenario, the locating and determination of the capacity of active and reactive resources has been accomplished with the approach of reducing losses and improving the voltage profile. However, in the second scenario, the locating and determining the capacity of these resources has been accomplished with loss and cost reduction approach and it was considered as constraint in voltage profile. In the third scenario, the simultaneous reduction of all three objective functions has been performed simultaneously. To validate the results obtained by the MOPSO algorithm, its results were compared with genetic and particle swarm algorithms. The results indicate better and more accurate performance of MOPSO algorithm in minimizing objective functions relative to other two algorithms.

In this analysis, the baffling method is used to increase the efficiency of channel heat exchangers (CHEs). The present CFD (computational fluid dynamics)-based work aims to analyze the constant property, steady, turbulent, Newtonian, and incompressible fluid flow (air), in the presence of transverse-section, arc-shaped vortex generators (VGs) with two various geometrical models, i.e., arc towards the inlet section (called arc-upstream) and arc towards the outlet section (called arc-downstream), attached to the hot lower wall, in an in-line situation, through a horizontal duct. For the investigated range of Reynolds number (from 12,000 to 32,000), the order of the thermal exchange and pressure loss went from 1.599–3.309 to 3.667–21.103 times, respectively, over the values obtained with the unbaffled exchanger. The arc-downstream configuration proved its superiority in terms of thermal exchange rate by about 14% than the other shape of baffle. Due to ability to produce strong flows, the arc-downstream baffle has given the highest outlet bulk temperature.

Solar energy is the most renewable energy widely spread on the globe with several applications such as power generation and thermal comfort amelioration inside buildings. In the present study, one of the multiple solar energy techniques is discussed. New, simple and low-cost solar chimney (SC) made of polyvinyl chloride (PVC) tube with internal PVC obstacles was investigated experimentally. Heat transfer of air passing through the new device were studied and results show SC ability of increasing air temperature from 25°C to 48°C and reducing relative humidity from 40% to 10%. Internal PVC obstacles were responsible for increasing outlet air temperature by more than 7°C in 63% of compared cases with simple PVC tube SC without internal obstacles. In the last part of the study, the new system was compared with three conventional square glazed SCs found in the literature. The new system outlet’s air temperature was higher by 12°C than the first two models and 2°C with the third model, which increase the kinetic energy of air leaving the building and increase the internal airflow, ameliorating the air quality and reducing the age of air inside the dwellings. Obtained results encourage building designers and people to widely use SCs.

The sizable global use of fossil energy and the worries about harmful emissions to the environment and human health have led investigations focused on using renewable fuels. Ethanol seems to be a desirable renewable fuel due to availability and significant production. The ethanol fumigation in compression ignition engines has been explored as a possible solution to enhance efficiency and decrease harmful and pollutant gases. This study investigates the effects of a generator set running on directly injected diesel fuel containing 7% biodiesel in volume and port fuel injected hydrous ethanol in different loads. The experiments were carried out in a diesel engine with specific loads, and the ethanol substitution rate ranged from 9% to 52% by energy. Results showed a significant decrease up to 61% in smoke opacity. An improvement of about 9.7% at 7.0 kW in global thermal efficiency was observed. Nevertheless, the other loads' efficiency deteriorated, resulting in a maximum decrease of about 14.6% at 4.0 kW. The total specific fuel consumption increased when ethanol was used, whereas the exhaust gas temperature decreased. The lowest NOX emissions found was 290 ppm at 6.0 kW and an ethanol energy ratio of 21%, although an increase in CO emissions was observed.

The current study aims to perform a geometrical investigation of an onshore Oscillating Water Column (OWC) on a large scale. The Constructal Design method is employed, aiming to maximize its available power. The OWC is subjected to two constraints (areas of the chamber and ramp below the chamber); and three degrees of freedom: height/length ratio of the chamber (H1/L1), height/length ratio of the ramp (H2/L2), and submersion of the frontal wall of the chamber (H3). A laminar, unsteady, incompressible, and two-phase flow was adopted, solving conservation equations of mass, momentum, and transport of water-air volume fraction using Finite Volume Method (FVM) and Volume of Fluid (VOF) model. The global optimal geometry led to a twice maximized available power 37.3% higher than the best case without the seabed ramp below the chamber and seven times better than the worst case. Concerning the sensibility of geometry, results indicated that the chamber geometry, given by ratio H1/L1, over the available power (P) was strongly affected by the ramp ratio H2/L2. Moreover, the behavior of the effect of H2/L2 over the once maximized available power (Pm) and corresponding optimal shape of the chamber, (H1/L1)o, changed dramatically for two different magnitudes of H3 investigated.

Mineral coal is the main source of energy generation in the world. In Brazil, this energy source has a smaller share in the internal energy supply, 5.5% of the total. Despite this, issues of energy security, stable and low prices make coal a strategic source. Due to this source's importance, this work aims to evaluate the clean technologies used to mitigate the emission resulting from the combustion of coal from a thermoelectric plant that applies low quality coal in Brazil using an analytical hierarchy process to classify the viable technological alternatives for the production process. The articulation of the environmental management system was adequate to meet the environmental demands and the energy efficiency of the thermoelectric plant. However, the results suggest that the investment in a coal processing plant would increase the fuel quality, a critical factor in the reduction of operating milling costs, in the ash circuit, and the treatment of gaseous emissions.

In the ongoing exploration, a mathematical model is analyzed to study the combined effects of centrifugal and buoyancy forces on fluid flow and heat transfer through a curved square duct of fixed curvature, δ = 0.1 . The outer and bottom walls of the duct are heated while the inner and ceiling walls are in room temperature. Firstly, grid efficiency for different Grashof numbers is checked with evaluating percent relative errors and then the accuracy of the numerical investigation with numerous articles is also compared. After numerical calculation, the steady solution branches with their linear stability have been performed by adopting spectral method. As a result, two branches of asymmetric steady solutions are obtained comprising with two- to four-vortex solutions. Linear stability analysis shows that only the first branch is linearly stable while the other branch is linearly unstable. It is found that the flow is stable at small values of Dean (Dn) whatever the Grashof (Gr) number is, and the stability is delayed as the Grashof number is increased. A substantial interaction is observed between the steady solution branches and the secondary flow structure. A diagram has also been presented which describes the creation of vortex structure of secondary flows for various Dn and Gr. Time history analysis shows that for G r = 200 periodic flow turns into steady-state flow before turning into periodic or multi-periodic oscillation once. For Gr > 200, however, the flow undergoes "multi-periodic/periodic → steady-state'', if Dn is increased. Phase space and power spectrum are obtained to confirm the non-linear characteristics of the flow. Nusselt numbers are computed as an exponent of heat transfer and it is detected that convective heat transfers to periodic and multi-periodic flows have boosted significantly more than steady-state flows. Finally, A comparison among the numerical data and experimental results has been conferred which has shown that there is good consent between them.

This study investigates the mixed convection heat transfer characteristics of micropolar nanofluid containing motile microorganisms as it is passing over a stretching sheet. The governing equations of the fluid flow and boundary conditions are solved via similarity analysis using the fourth-order Runge–Kutta method. To verify the accuracy and validity of the method, the results are compared with those of several previous studies. The results are presented in terms of distribution of the velocity, particle micro-rotation, temperature, nanoparticle concentration, and density of motile microorganisms over the stretching sheet. The skin friction, coupled stress, mass transfer rate, and the rate of microorganism transfer away from the sheet are also examined. It can be concluded that the Nusselt number, coupled stress, friction coefficient, and Sherwood number are independent of the bioconvection Lewis number Lb. On the other hand, the rate of motile microorganism transfer away from the sheet to the fluid increases with Lb.

This study explores the heat transfer characteristics of nanoliquid flowing over a rotating disk in the presence of the applied magnetic field and convective boundary condition. The nanoliquid is flowing due to the rotation of the disk with uniform stretching of a disk along the radial direction. Effects of ESHS (exponential space-related heat source) and THS (thermal-related heat source) are the focal concern of this article. The effective thermal conductivity of ethylene glycol (EG)-based graphene oxide (GO) nanoliquid is estimated by using Nan’s model whereas effective dynamic viscosity is calculated through Brinkman model. The partial differential system which governed the problem is transformed by using Von-Karman stretching transformations to the ordinary differential system. The subsequent two-point ODBVP (ordinary differential boundary value problem) is treated numerically. The consequence of effective parameters of the problem on different flow fields is illustrated graphically. The numerical values of shear stress and heat transfer rate (Nusselt number) are also calculated. Further, the slope of the data points is determined to quantify the outcome. Validation of the present results is made by direct comparison with the available results and an excellent agreement is found. It is found that the rate of heat transfer increased with nanoparticle volume fraction at the rate 0.4153 and the friction factor increased by increasing nanoparticle volume fraction at the rate 3.0681. The fluctuation rate of Nusselt number due to the variation of the ESHS parameter is almost three times more than that of THS parameter.

The present study deals with computational investigation of natural convection in a porous chamber having a copper finned heat sink and a thermally producing element of finite thickness and heat conductivity. The enclosure is cooled from the external vertical and upper horizontal walls, whilst the remaining borders are considered to be thermally insulated. Newtonian and heat-conducting liquid with temperature-dependent viscosity is assumed as a working medium. Governing equations are written in non-dimensional variables «stream function—vorticity—temperature» and they are worked out by the finite difference technique. The temperature distribution, streamlines and the dependences of the integral characteristics on the governing characteristics, such as the Darcy and Ostrogradsky numbers and geometric characteristics of the radiator have been illustrated. Presented results can be used for the development of passive cooling systems.

Arid regions around the world are characterized by hard summer and winter seasons, which leads to thermal discomfort. The southwest of Algeria is classified as an arid region, where the temperature in the summer season passes sometimes 50 °C in the shade and reaches negative values in the winter season. In addition, the yearly relative humidity is below 50%. The hard thermal and hygrometric situation requires actions to fulfill the thermal comfort requirements. Air-conditioning systems are a solution, but at the same time, they are responsible for a big amount of energy consumption in the building sector. In the present paper, an experimental investigation is conducted on the performance of a coupled system: earth-to-air heat exchanger and a solar chimney. The main purpose is to reduce costs and maximize the direct effect between the two techniques. The obtained results showed that the new system was able to create two main thermal regimes in the same day. The first one is a ‘heating’ by increasing the outlet air temperature passing through the buried pipe and solar chimney to reach a maximum gain of 14 °C in day 3. The second thermal regime is the ‘cooling’ that is made by reducing the air temperature at the EAHE outlet by 11.6 °C on day 5. It is also observed that the system increases the outlet air relative humidity by 46% due to the condensation phenomena and reduces it sometimes by 45%. The recent model made of the two techniques was able to produce between 3 and 20 Watts of heating/cooling capacity at the outlet of the system.

The paper analyzes steady laminar boundary layer flow of low-conductivity Casson fluid over a stretching/shrinking sheet subjected to a transverse magnetic field in the presence of suction/injection when the fluid far away from the surface is at rest. This flow problem is mathematically modelled and the non-Newtonian fluid under consideration obeys the rheological equation of state by the Casson model. A similarity transformation converts the governing nonlinear partial differential equations into nonlinear ordinary differential equations, which are solved analytically. Using the stream function and velocity components, these results are analyzed in dependence on the Casson fluid parameters, Chandrasekhar number, and mass transpiration parameters.

The aim of the present investigation is framing the effect of thermal radiation and slip on a magnetohydrodynamic (MHD) Casson nanofluid flow over a stretching surface under the influence of variable viscosity and convective boundary condition. First, non-dimensionally developed boundary layer equations are deduced with suitable transformations. Then they are solved numerically by the Runge–Kutta–Fehlberg method with the shooting technique for different values of parameters. The most relevant result of the present study is the fact that the augmented magnetic field strength, Casson fluid parameter, and the inclined angle undermine the flow velocity, establishing thinner hydrodynamics boundary layer, while the thermal slip and radiation parameters show the opposite trend. Another most important outcome is the fact that increase in the Prandtl number, radiation, viscosity, thermal slip, and radiation upsurges the fluid temperature, leading to improvement in the thermal boundary layer. The effects of different natural parameters on the skin friction coefficient and the Nusselt and Sherwood numbers are examined graphically. For a limiting case of the present model, the obtained solution was found to be in excellent agreement with the existing literature.

Combustion-chamber is a critical component of the propulsion engine, which is widelyused in the space industry and aeronautics. The goal of this article is to perform a numericalanalysis on the combustion process using a liquid-type propellant. The steps that must be followeduntil total combustion is achieved are emphasized. It concerns the fuel feeding phase, its injectionand the combustion operation. The amount of combustion products and the energy generated areevaluated. It has been shown that the liquid propellant may present an efficient alternative fuelthan the kerosene. In addition, the temperature of combustion does not exceed a certain limit toavoid structural problems in the chamber. The parametric survey allowed determining the range ofthe most influence factors, including the pressure, mixture richness, velocity and flow rates ofinjection for the fuel and oxidizer. The number and type of injectors revealed a considerableinfluence on the velocity and flow rates of injection. To maximize thrust force and systempropulsion, a careful selection of chamber material and ignition methods is required. A thorough inspection on the issues of walls cooling showed the necessary survey of maximum temperaturesthat may be reached during the combustion. Finally, an investigation of the thermal exchangethrough the walls will be very interesting.

Solar energy is an infinite, unpredictable and enduring energy source among all other incompatible energy options. This work simulates the feasibility of installing a photovoltaic (PV) system isolated with batteries in a typical residential center in M'sila, Algeria, where the study is carried out to assess solar radiation and evaluate the technical and economic aspects of the PV system to supply domestic electrical energy needs. The program has been implemented by PVsyst6. The daily electricity consumption is about 12.6 kWh/day. On an annual basis, the energy that is injected into the grid is 4615 kWh. The average performance ratio (PR) of the Si-poly PV system is operated at 62.9% in the simulated study for the planned location. The maximum electrical energy produced was from June to August, when it reached 354.4 kWh of July. The losses recorded in the study were principally due to temperature of photovoltaic field, which was 12.14%.

An analysis of the thermoelectric characteristics of certain recently discovered materials is carried out in this investigation. The alloy of iron, vanadium, tungsten, and aluminum (Fe2V0.8W0.2Al) applied to a silicon crystal is compared to new inorganic thermoelectric materials, which are mosly oxides like NaCO2O4. For both materials, the thermoelectric effects, Seebeck effect, Peltier effect, Thomson effect, and Kelvin relations are described. The cooling rate’s influence on the energy balance is also assessed. The traditional thermoelectric materials provided are mostly made up of toxic, rare and/or expensive elements, which makes large-scale thermoelectric generator integration difficult. In recent decades, research has shifted toward the development of novel materials with a better price-to-performance ratio. Despite a low conversion yield, the family of oxides offers significant benefits in this respect, which are particularly evident at high temperatures. The findings of our study indicated that Fe2V0.8W0.2 applied to a silicon crystal has good thermoelectric characteristics. A sufficient merit factor was found in the new substance under investigation.

In recent decades, there has been an increasing trend toward the technical development of efficient energy system assessment tools owing to the growing energy demand and subsequent greenhouse gas emissions. Accordingly, in this paper, a comprehensive emergy-based exergoeconomic (emergoeconomic) method has been developed to study the biomass combustion waste heat recovery organic Rankine cycle (BCWHR-ORC), taking into account thermodynamics, economics, and sustainability aspects. To this end, the system was formulated in Engineering Equation Solver (EES) software, and then the exergy, exergoeconomic, and emergoeconomic analyses were conducted accordingly. The exergy analysis results revealed that the evaporator unit with 55.05 kilowatts and the turbine with 89.57% had the highest exergy destruction rate and exergy efficiency, respectively. Based on the exergoeconomic analysis, the cost per exergy unit (c), and the cost rate (C˙) of the output power of the system were calculated to be 24.13 USD/GJ and 14.19 USD/h, respectively. Next, by applying the emergoeconomic approach, the monetary emergy content of the system components and the flows were calculated to evaluate the system’s sustainability. Accordingly, the turbine was found to have the highest monetary emergy rate of capital investment, equal to 5.43×1012sej/h, and an output power monetary emergy of 4.77×104sej/J. Finally, a sensitivity analysis was performed to investigate the system’s overall performance characteristics from an exergoeconomic perspective, regarding the changes in the transformation coefficients (specific monetary emergy).

The difficulty of a particle traversing a gaseous mean is one of the most challenging modelling problems in science. This applies to a water droplet travelling from the nozzle to the ground in sprinkler irrigation. The challenge primarily refers to the intense difficulty in writing and solving the system of governing equations for such a complicated process, where many non-linearities occur when describing the relationships and dependences between one influential parameter and another. When a multi-droplet system is considered instead of just a single droplet, the problem becomes even more complicated because, in addition to inter-parameter dependencies, an inter-droplet reciprocal affection is observed, owing to electrical interactions between the hydrogen and oxygen atoms of the different water molecules. A quantum approach has recently been proposed as an alternative to traditional classic approaches to analyse water droplet dynamics in sprinkler irrigation, but the entire classic-quantum and single-droplet versus multi-droplet alternatives need to be discussed and pinpointed, which is one of the main goals of the current paper, which focuses on the theoretical part of the issue, thus highlighting the new perspectives of a deeper comprehension in the spray flow related phenomena.

The work presents a numerical study of a wave energy converter (WEC) device based on the oscillating water column (OWC) operating principle with a variation of one to five coupled chambers. The main objective is to evaluate the influence of the geometry and the number of coupled chambers to maximize the available hydropneumatic power converted in the energy extraction process. The results were analyzed using the data obtained for hydropneumatic power, pressure, mass flow rate, and the calculated performance indicator’s hydropneumatic power. The Constructal Design method associated with the Exhaustive Search optimization method was used to maximize the performance indicator and determine the optimized geometric configurations. The degrees of freedom analyzed were the ratios between the height and length of the hydropneumatic chambers. A wave tank represents the computational domain. The OWC device is positioned inside it, subject to the regular incident waves. Conservation equations of mass and momentum and one equation for the transport of the water volume fraction are solved with the finite volume method (FVM). The multiphase model volume of fluid (VOF) is used to tackle the water–air mixture. The analysis of the results took place by evaluating the performance indicator in each chamber separately and determining the accumulated power, which represents the sum of all the powers calculated in all chambers. The turbine was ignored, i.e., only the duct without it was analyzed. It was found that, among the cases examined, the device with five coupled chambers converts more energy than others and that there is an inflection point in the performance indicator, hydropneumatic power, as the value of the degree of freedom increases, characterizing a decrease in the value of the performance indicator. With the results of the hydropneumatic power, pressure, and mass flow rate, it was possible to determine a range of geometry values that maximizes the energy conversion, taking into account the cases of one to five coupled chambers and the individual influence of each one.

This work presents a numerical study of incompressible, laminar, two-dimensional, mixed convection flows in horizontal channels with two rectangular alternated blocks mounted in the surfaces. The influence of the geometry and positioning of the blocks on the heat transfer rate is evaluated using Constructal Design. The problem is subjected to two geometric constraints associated with the areas of the channel and the two blocks and three degrees of freedom: $$H_{1}/L_{1}$$ (the ratio of the height to the width of the upstream block), $$H_{2}/L_{2}$$ (the ratio of the height to the width of the downstream block), and $$L_{3}$$ (the horizontal distance between the centers of the blocks). The purpose is to maximize the heat transfer rate per length unit $$q'$$ considering three different Reynolds ($$Re_{H}= 10$$, 100, and 200) and Grashof numbers ($$Gr_{H} = 650$$, 6,500, and 65,000). The conservation equations of mass, momentum, and energy are solved using the Finite Volume Method, and the buoyance forces are modeled with the Boussinesq approximation. In general, the best performance is reached for the largest intrusion of the blocks. However, changes in $$Gr_{H}$$ and $$Re_{H}$$ affected the optimal distance ($$L_{3})_{o}$$, and for $$Gr_{H}=65,000$$ non-symmetrical blocks led to the best performance, showing the importance of design investigation for different flow conditions.

Aspire of this study is to study the effect of heat source, suction/injection, and chemical reaction on dissipative and radiative MHD flow of a Casson fluid over an exponentially permeable stretching sheet. Series solutions are obtained for converted non-dimensional ordinary differential equations using an analytical technique known as the homotopy analysis method (HAM). A decisive approach of convergence of series solutions is also furnished. The acquired results are in excellent correlation with the previous results. The nature of different parameters like the magnetic parameter, exponential parameter, suction/injection parameter, the Casson parameter, radiation parameter, the Prandtl number, the Eckert number, heat source parameter, Schmidt number, and chemical reaction parameter are discussed using tables and graphs.

In the present investigation, asymptotic solutions are obtained regarding the laminar natural convection of a nanofluid in a porous enclosure subject to internal heating and magnetic field, which appears in a plethora of industrial and bioengineering applications. The complicated nature of the nanofluids along with the computational time needed for the magnetohydrodynamic numerical simulations makes this problem too difficult to face with. Hence, the innovation of this study relies on providing a first-principles approach that includes three kinds of widely utilized nanoparticles (Cu, Al2O3 and TiO2) dispersed in aqueous suspension by incorporating a unified way for describing the nanofluid thermal conductivity and viscosity. In addition, the effect of the magnetic field, internal heating, porous medium permeability as well as nanoparticle size and volume fraction is examined via the derived analytical relationships. In brief, the current study suggests that the increase in the magnetic field intensity and the decrease in the medium permeability tend to suppress the nanofluid flow, thus resulting in deterioration of the heat transfer. This deterioration also occurs when the nanofluid becomes denser and the nanoparticles enlarge. Conversely, increasing the internal heating reinforces the convective currents in favor of cooling process. Finally, the present asymptotic solutions are expected to be very useful in various scientific fields given the rapidly growing interest in nanofluids.

The main focus of the present research work is to elaborate the Reiner–Philippoff fluid flow over a stretching sheet along with thermal radiation effect. A Darcy–Forchheimer medium was imposed and a linear stretching surface was used to generate the flow. Application of appropriate transformation yields nonlinear ordinary differential equation through nonlinear Navier–Stokes equations and solved by Runge–Kutta–Fehlberg shooting technique. Importance of influential variables such as velocity and temperature was elaborated graphically. It is envisaging that the boost up values of γ declines the both velocity and temperature profiles.

In this paper, the nanofluid flow near an infinite disk which stretches in the radial direction in the presence of exponential space-based heat source (ESHS) and thermal-based heat source (THS) is investigated. The Brownian motion and thermophoresis effects are accounted to study the nanofluids. Effects of radial magnetism and the Coriolis force are also deployed. The pertinent nonlinear equations are approximated under boundary layer notion and modified von Karman transformations. The subsequent nonlinear differential system is treated via shooting method. The impacts of controlling parameters on flow profiles are discussed and depicted with the aid of graphs. Results show that as the ESHS and THS parameters increase, the thermal field increases. However, ESHS phenomenon is highly influential than THS phenomenon on energy transport and its gradient. Further, it is found that thermophoresis slip mechanism has more effect on heat transport rate than the Brownian motion.

MHD flow of an electrically conducting Newtonian fluid over a super linear stretching sheet in the presence of suction/injection and Navier slip is studied using modified Adomain decomposition method (MADM) and Pade approximants. Governing nonlinear partial differential equations are transformed into nonlinear ordinary differential equations using an appropriate similarity transformation. The transformed equations are solved analytically by the modified ADM and Pade approximation. The modified ADM for solving nonlinear differential equations is purely and solely the traditional Taylor’s series method. Pade approximants are applied to increase the convergence of the given series. The developed analytical technique is verified comprehensively. It is found that Navier’s slip condition can lead to a non-essential growth of the boundary layer thickness and a decrease in the axial and transverse velocities.

In the present study, a finite volume method is used to investigate heat transfer and flow friction behavior of non-Newtonian nanofluids. To study a practical application of the mentioned concept, a simple model of a parabolic trough solar receiver is simulated. The main objective of the present study is to investigate the effect of non-Newtonian behavior of the working fluid on the performance of a parabolic trough solar collector. The heat transfer fluid is assumed to be a non-Newtonian nanofluid, and the flow regime is considered to be laminar. The effect of Cu nanoparticle addition on heat transfer coefficient and flow friction of Newtonian, shear-thinning and shear-thickening nanofluids are studied. To comprehensively investigate the effect of buoyancy-driven secondary flows on the average Nusselt number and friction factor of the absorber tube, simulations are carried out for different Grashof numbers (Gr = 105, 106, 107), Reynolds numbers (Re = 200, 500, 1000), Cu nanoparticle volume fractions (φ = 0, 0.01, 0.03) and non-Newtonian power-law indexes (n = 0.25, 0.75, 1, 1.25, 1.75). It is concluded that when shear-thickening nanofluids are utilized as the working fluid, nanoparticle addition makes no sensible changes in the average Nusselt number. Besides, for all values of non-Newtonian power-law index, variations in volume fraction values do not have any significant effect on the friction factor. Furthermore, it is shown that when the working fluid is shear-thinning, nanoparticle addition triggers to considerable increment in Nusselt number. At high Grashof and Reynolds numbers, the ratios of Nusselt number and friction factor of shear-thinning nanofluids (n = 0.25) to those of shear-thickening nanofluids are up to 3.57 and 0.08, respectively.

One of the primary factors affecting the amount of worldwide energy consumption and greenhouse gas emissions is cooking. Solar cooking is an appropriate solution because it is both inexpensive and expandable. To illustrate modern advancements and the current status of solar cooking technology, this paper presents a review of recent experimental and analytical socioeconomic studies on solar cookers. The experimental studies have been divided into three categories based on different solar cooker structures: (i) box types, (ii) concentrating types, and (iii) panel types. Next, different designs are investigated according to their direct or indirect heat transfer modes and optional equipment for latent heat and sensible heat type thermal storage units. Moreover, reviews of studies concerning social and economic points of view and analyses of solar cooking technology are included. Different designs and configurations of solar cookers are compared for their performance, including economic aspects. Finally, some applicable solutions for current drawbacks are presented as a pathway for further investigation in solar cooking technology.