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This paper presents the numerical results of particle propagation in open space, taking into account the temperature of the human body and the surface of the ground. And also, the settling of particles or droplets under the action of gravitational force and transport in the open air is taken into account, taking into account the temperature during the process of breathing and sneezing or coughing. The temperature of the body and the surface of the ground, different rates of particle emission from the mouth, such as breathing and coughing or sneezing, are numerically investigated. The effect of temperature, cross-inlet wind, and the velocity of particle ejection from a person's mouth on social distancing is being investigated using a numerical calculation. The variable temperature of the human body forms a thermal plume, which affects the increase in the trajectory of the particle propagation, taking into account the lateral air flow. The thermal plume affects the particles in the breathing zone and spreads the particles over long distances in the direction of the airflow. The result of this work shows that in open space, taking into account the temperature of the body and the surface of the ground, a 2-m social distance may be insufficient for the process of sneezing and social distance must be observed depending on the breathing mode.

In this work, numerical modeling and assessment of the dispersion of pollutants as a result of a chemical reaction from the activities of the Ekibastuz SDPP-1 was considered. The simulation was done on a valid thermal power plant. At the same time, to model the dispersion of pollutants NO, NO2 and CO were used, and the products NO2, HNO3 and CO2 from a chemical reaction with oxygen were also considered. The validation of the mathematical model, taking into account the chemical reaction, was carried out using several test problems and the obtained numerical results were compared with experimental data and numerical data of other authors. So in this work, estimates of the concentration level were given, both for pollutants and for products that were formed from a chemical reaction. As a result, the mass fractions of concentration and product were determined during a chemical reaction for various distances from chimneys. According to the data obtained, it can be noticed that, under the influence of diffusion, concentrations and products during a chemical reaction spread wider in width and due to this diffusion, the concentration level with an increase in the distance from the chimneys is lower. So, according to the data obtained, it is possible to assess the choice of the optimal distance of the thermal power plant from residential areas, at which the concentration of emissions and products from a chemical reaction will remain at a safe level.

In this paper, a numerical simulation of air pollution and the particles distribution in idealized urban canyons with aspect ratio 1 for various thermal conditions was considered. To solve the problem, the RANS equations were used, while various turbulent models were used to close this system of equations. To validate of the mathematical model was solved the test problem in isothermal condition numerically. The various turbulent models results were compared with empirical and modeling results. The main problem was described as the pollutants emission process and particles between houses using various grass barrier types under different temperature regimes. The results of computational simulation without grass barrier were compared with the calculated values using different types of grass barriers. In the course of various studies, it was found that the existence of barriers along the streets reduces the concentration of harmful substances and the concentration of particles in the air. Increasing the thermal value for a roadside barrier reduces deposition and dispersion of pollutants.

In this research paper, comprehensive thermodynamic modeling of an integrated energy system consisting of a multi-effect desalination system, geothermal energy system, and hydrogen production unit is considered and the system performance is investigated. The system's primary fuel is a geothermal two-phase flow. The system consists of a single flash steam-based power system, ORC, double effect water–lithium bromide absorption cooling system, PEM electrolyzer, and MED with six effects. The effect of numerous design parameters such as geothermal temperature and pressure on the net power of steam turbine and ORC cycle, the cooling capacity of an absorption chiller, the amount of produced hydrogen in PEM electrolyzer, the mass flow rate of distillate water from MED and the total cost rate of the system are studied. The simulation is carried out by both EES and Matlab software. The results indicate the key role of geothermal temperature and show that both total exergy efficiency and total cost rate of the system elevate with increasing geothermal temperature. Also, the impact of changing absorption chiller parameters like evaporator and absorber temperatures on the COP and GOR of the system is investigated. Since some of these parameters have various effects on cost and efficiency as objective functions, a multi-objective optimization is applied based on a Genetic algorithm for this system and a Pareto-Frontier diagram is presented. The results show that geothermal main temperature has a significant effect on both system exergy efficiency and cost of the system. An increase in this temperature from 260 C to 300 C can increase the exergy efficiency of the system for an average of 12% at various working pressure and also increase the cost of the system by 13%.

This research article uncovers a novel mathematical model that interprets the peristaltic flow in elliptic duct with heat and mass transfer for the first time. A unique mathematical technique is introduced in this study that provides exact analytical solutions for partial differential equations. The Cartesian coordinate system is used in the present analysis and the non-circular form of duct is attained by considering equation of ellipse in the boundary conditions. The temperature, concentration and velocity profile are exactly computed and analyzed through graphical results. The axially symmetric flow behaviour is revealed by the graphical outcomes. Concentration, velocity and temperature profiles have parabolic shapes and axially symmetric behaviour.

This novel investigation unfolds the mathematical model of peristaltic flow in an elliptic duct having ciliated walls. The current assessment is carried out by considering a heated Newtonian viscous fluid in this ciliated elliptic duct. A detailed heat transfer study combined with various physical aspects of peristalsis is provided. We have incorporated the appropriate and useful transformations that simplify this mathematical problem into its non-dimensional form with relevant non-dimensional boundary conditions over the surface of ciliated elliptic duct. Finally, the exact mathematical results are computed for this interesting problem. A thorough graphical assessment is also included for a complete understanding of mathematical results. The axially symmetric flow behaviour is noted for both velocity and temperature profiles in this elliptic duct having ciliated walls.

Nowadays, generating energy is discussed as a paramount option in waste management, because the share of energy from waste is increasing annually. The ever-increasing need for energy and limitations of using fossil resources, and also the increase in environmental pollution from consuming these resources have made the use of renewable energies of especial importance. In this research, we first studied renewable energies, followed by technologies related to the biogas system. Biogas systems have been referred to by landfill and discussed comprehensively in this scheme for utilization. For this purpose, the input source of this system is considered as the volume of garbage in the city of Germi as the study area. In the next step, the amount of garbage produced in this city was extracted and the Landfill software was used for methane production potential assessment from this system and the Homer software was used for economic analysis and reliability evaluation. The most important results are payback period, which is about 10 years, and the amount of electricity produced per year, which is 11658.265 MWh.

Wireless sensor networks (WSNs) especially with sensor nodes communicating with each other in medium other than air have been naive area of research since the last few years. In comparison to underwater communication, wireless underground sensor networks (WUSNs) are now being used in a large number of applications ranging from environmental observation, estimating chances of earthquake, communicating in underground tunnels or mines, and infrastructure monitoring to soil monitoring for agricultural purposes. In spite of all such promising applications, due to harsh and dynamically changing soil characteristics including soil type, water content in soil, and soil temperature, underground communication with conventional electromagnetic (EM) wave-based technology could not prove to be feasible for long-distance communication. Alternatively, due to magnetic permeability of soil being similar to air, magnetic induction- (MI-) based approach was adopted using magnetic coils as antenna for sensor nodes. Subsequently, MI waveguide and 3D coil mechanisms were considered to improve the system efficiency. Attributing to different characteristics of underlying transmission channels, communication protocols as well as architecture of MI-based WUSNS (MI-WUSNs) have been developed with different approaches. In this review paper, in addition to the latest advancements made for MI-WUSNs, closely associated areas of MI-WUSNs have also been explored. Additionally, research areas which are still open to be worked upon have been detailed out.

In the present research, dual-nozzle swirl generator was installed at the blocked end of the straight tube to inject flow tangential to the wall of the pipe with various injection inclinations compared to the longitudinal axis. This causes a swirl flow inside the pipe. Altering some decisive variables, including injection angle, side of nozzle cross-section, pipe diameter, and flow rate, caused to attain various cases with unique hydraulic-geometrical characteristics. Classes ‘A…-D50-N…-M…’ and ‘A…-D20-N…-M…’ bear the main characteristics of the cases embodied in their sub-classes. Entropy generation (St), Nu*, NE, Heat Transfer Improvement (HTI) index and ${\eta}_{w-s}$ were used as effective tools for the basement of the system based on the irreversibility concept. The results showed that all of the cases of class ‘A…-D50-N…-M…’ cause lower frictional-contributed and higher thermal-contributed entropy generation compared to the class ‘A…-D20-N…-M…’. The highest values of the HTI index are 1.5 and 1.763 obtained by ‘A30-D20-N5-M0.4’ and ‘A90-D20-N6.25-M0.1’, respectively.

This is a numerical research that aims to design several helically grooved coils for solar water heating systems and compare them based on the irreversibility concept. To this end, helical coils with circle, square, horizontal elongated circle (HEC), and vertical elongated circle (VEC) cross-sections were annularly grooved for enhancing heat transfer rate. The Second law analysis in this study was performed based on several variables including flow rate (1–6 lit/min), geometrical, temperature (283–323K), and type of working fluid. Depth and distance of grooves were considered as geometrical parameters. Water, EG (CH2OH)2 (IUPAC name: ethane-1,2-diol), and Theminol-55 were used as heat transfer fluids. Selected fluids make a Pr range of 3.35–744. Various entropy-based indicators were used to select the most optimum condition. Moreover, the interactions between triple thermodynamic domains (energy, entropy, and exergy) were conceptualized. Results demonstrated that for all cases the highest entropy generation can be achieved in the higher flow rates (6 lit/min), also when groove depth and distance are, respectively, 1.3 mm and 20 mm. Case ''VEC'' has the lowest ratio of grooved dimensionless entropy to un-grooved dimensionless entropy.

In this analysis, the modified nanofluid flow at a nonlinear stretching Riga plate is considered. The impacts of variable viscosity are considered. The modified nanofluid is the extended version of the hybrid nanofluid. This is the mixture of three nanoparticle and base fluid. The heat transfer rate depends on the thermal conductivity because heat transfer rate and thermal conductivity directly proportion which provided in the literature. The developed model solved through numerical technique. The basic achievement of this analysis is to explore about the heat transfer improvement that gains higher as compared to Hybrid nanofluid and nanofluid, (see Fig. 1 ). Heat transfer properties and modified nanofluid show exciting behavior which deserve further study on the modified nanofluid. The ϕ 3 disperse the energy in the shape of heat than the mixture of more nanoparticles may more exert energy in the form of heat.

The current work proposes and investigates a novel multigeneration system (power, hydrogen, and energy) comprising a flash-binary geothermal power plant, a modified Kalian cycle, a low-temperature electrolyzer, and a reverse osmosis desalination setup. Indeed, the whole system has been devised regarding the multi-heat recovery technique and smart management of products through a structural modification. To emphasize the ability of the newly designed system in this work, the data of the Sabalan geothermal plant in Iran has been used as a case study. Subsequently, the feasibility of the proposed multigeneration system has been examined by the modified specific exergy costing (M-SPECO) method, characterizing the exergetic and cost aspects of the system. The M-SPECO method is recognized as an energy level-based cost scrutiny technique to evaluate energy conversion systems. Accordingly, the sensitivity study through single and dual parametric analyses has been implemented, wherein separator 1 pressure was the main parameter. Likewise, the non-dominated sorting genetic algorithm-II (NSGA-II) method has been applied to optimize the calculations and reveal the optimum conditions and results. In this way, the achieved optimum exergy efficiency of the system was calculated as 47.25%, followed by a value of 7.66 $/GJ for the modified overall unit cost of products.

In this numerical study, an attempt has been made to improve the thermal performance of the flat-plate solar collector (FPSC) by inducing the swirl flow inside the tube by the considered nozzles. To this end, the effect of the number of circumferential nozzles and their inclination angles was taken into the account. The considered number of nozzles was "single", ''dual'', ''triple'', and ''quad''. For each of the said cases, the inclination angle of nozzles was taken 30°, 45°, 60°, and 90° (A30, A45, A60, A90). Moreover, the mass flow rate of single-nozzle pipe was considered 0.2 kg/s, 1 kg/s, and 2 kg/s. To analyze all of the cases under identical conditions, the said mass flow rates were distributed equally among all of the nozzles (for ''dual'', ''triple'', and ''quad''). All of the characteristics were defined in a form of "A…-D…-N…-M…'' where ''A…'', "D…", "N…", and "M…" stand for angle of injection, diameter of pipe, nozzle cross-section edge, and mass flow rate, respectively. Numerical simulation (3-dimensional) of the system was performed by Finite Volume Method (FVM). The turbulence nature of flow was simulated by the k-omega SST (shear stress transport) turbulent model. Results showed that the "single-nozzle'' swirl generator had the highest thermal performance factor (TPF) so that for all cases its values were greater than unit. Mass flow rate growth increases Nu, heat extraction rate, and kinetic energy rate (KER) while drops friction factor and outlet temperature. Increment of injection angle increases outlet temperature and friction factor and reduces KER. The maximum and minimum values of TPF are 4.19 and 0.44 which belong to "single; A30-D50-N12.5-M0.2" and "quad; A90-D50-N12.5-M0.5", respectively.

This article explicates the blood flow across an artery with multiple stenosis at outer wall and a thrombus at the centre. The symmetric multiple stenosis and non-symmetric multiple stenosis shapes are both considered in this study. Entropy analysis is also taken into account for a detailed study of irreversibility. The governing equations are interpreted with provided boundary conditions and exact mathematical solutions are developed. Further, these exact solutions are elucidated graphically. Streamlines show that the closed contours are symmetric in shape for symmetric multiple stenosis but non-symmetric in shape for non-symmetric multiple stenosis shape. The increase in multiple stenosis heights, increases the shear stress at wall having multiple stenosis.

Due to its inherent ability of augmenting power system stability limit while maintaining good electric Power Quality (PQ), Power System Stabilizer (PSS) is envisaged to be an effective device in numerous Distributed Generation (DG) applications. It becomes a paramount work to maintain stable frequency, and alleviate the utility-grid collapse. Owing to this, this paper evaluates the performance of generic, and Multiband (MB)-PSSs for a hybrid 9 MW wind farm connected with mini/micro hydro power plant. The proposed system is interfaced with 200 MVA, 25 kV utility-grid system. A comparative analysis in the performance of a generic-PSS is presented with a MB-PSS at various voltage level points and power flows at various Point of Common Couplings (PCC) are analysed. Transient analysis is carried out during the presence of various unsymmetrical faults. It is envisaged that transients and unbalanced voltage sag-swells are mitigated at various PCCs while maintaining uninterruptable real and reactive power flows. The superiority of MB-PSS is established over generic-PSS in maintaining optimal PQ flow. Consequently, the reactive power requirement of the connected load is compensated by wind and mini/micro hydro controlling schemes using MB-PSS. Overall, the accurateness of the developed simulink models is demonstrated and satisfactory results are obtained in comparative analysis of both stabilizers.

Owing to enormous increase in the automobile population, traditional petroleum fuels for internal combustion engines will be usable only for a few years. Moreover, by releasing toxic emissions into the atmosphere at higher levels these fuels create severe environmental problems. In general, Carbon-monoxide (CO), Unburnt hydrocarbons (UHC), and smoke are emissions emitted by engines. The pollution of the environment can be controlled by replacing petroleum fuel with the use of alternative fuels like acetylene gas, hydrogen, CNG, LPG etc. In this current research, an experimental investigation was carried out in Compression Ignition engine using acetylene fuel, further enhancing the performance and emission properties by using diethyl ether (DEE) and ethanol as oxygenated fuel. In view of the performance and outflow (emission) parameters optimizing valve of acetylene gas as 12 lpm with oxygenated fuels, the performance and outflow characteristics were improved. The findings show an enhancement in brake thermal-efficiency of up to 3 to 4%, a decrease in exhaust temperature and emissions like CO, UHC and smoke of up to 40%, 20%–30% and 10%–35% respectively, there is decrease in fuel consumption of 10%–30%. It was found that ethanol is better than diethyl ether and diesel fuels when used as an oxygenated fuel with acetylene gas. In view of the performance and emission parameters, the best oxygenated fuel is ethanol and the optimize blend for diesel engine is E15+A12.

In the present work, a modified numerical model was developed to simulate the water flow during a dam break with the mud layer transfer of different heights, consisting of three phases (water, air, and a phase for deposition). To carry out a numerical simulation of this process, a mathematical model based on the VOF (volume of fluid) method was modified, taking into account the movement of the water-free surface, which is carried out by the movement of water flow based on the Newtonian fluid model, and the movement of mud impurities is based on the non-Newtonian fluid model. Validation of the constructed model for the influence of three-dimensional features of the flow on morphological changes is carried out by a modified mathematical model and compared with the results of calculation for two-dimensional (2D) and three-dimensional (3D) models. The proposed method for modeling is applied on a real complex terrain, which was based on the Kargalinka – a river in Almaty and the Almaty region of Kazakhstan, the right tributary of the Kaskelen River. Simulation analysis is carried out for cases with different deposit heights. All results of the numerical simulation can be visually viewed using graphs and illustrations.

The estuary of a river can be seen as a relatively free and partially closed coastal body. It is connected to the ocean and is a transitional zone of rivers, which contains processes from land to sea and from fresh water to salt water. The estuary is one of the most productive natural habitats in the world and carries a large number of sediments due to natural factors such as changes in runoff and tides. Therefore, many coastal areas with river estuaries have become the most densely populated areas in the human population. In this paper, the RSM (Reynolds stress model) turbulence model and the PID (proportional integral derivative) algorithm are successfully used to simulate the dynamic model and for the numerical simulation of the formation of turbidity maximum zone in the estuary, which provides a theoretical basis for the follow-up of the similar research studies.

Metal-organic frameworks are a new class of materials for hydrogen adsorption/storage applications. The hydrogen storage capacity of this structure is typically related to pressure, temperature, surface area, and adsorption enthalpy. Literature provides no reliable correlation for estimating the hydrogen uptake capacity of MOFs from these easy-measured variables. Therefore, this study introduces several straightforward and accurate artificial intelligence (AI) techniques to fill this gap, initially determining the appropriate topology of AI-based methods, then comparing their performances by statistical criteria, and introducing the most accurate. This study used artificial neural networks, hybrid neuro-fuzzy systems, and support vector machines as estimators. The general regression neural networks (GRNN) with a spread of 7.92 × 10−4 shows the highest correlation with the literature data and provides a relative absolute deviation of 5.34%, mean squared error of 0.059, and coefficient of determination of 0.9946.

Natural air ventilation in the hot‐dry regions plays a key role to decrease indoor air temperature in hot season, also to improve thermal comfort during the cold season. One of the most common ways to take advantage of natural ventilation is using wind catcher with an underground tunnel. In this method, the tower catches the airflow and directs it to the underground tunnel to decrease the air temperature by transferring heat to the ground, which is cooler in the summer and warmer in the winter. Earth‐to‐air heat exchanger (EAHE) is a modern form of wind catcher with underground tunnel. In this method, air after passing through buried pipes exchanges heat with the ground, and its temperature increases in the winter and decreases during the summer. This study analyzes the energy performance and cost‐effectiveness of earth‐to‐air heat exchanger to be utilized in a residential building in climate condition of the province of Kermanin Iran. In this regard, 9 different configurations of the EAHE are investigated to find the optimized EAHE. The system performance and cost‐effectiveness are studied in 3 different depths including 1, 2, and 3 m with 3 different pipe lengths including 25, 50, and 75 m. The results show that the EAHE is capable of reducing the inlet air temperature by 0.5‐9.9℃ in the summer and increasing it by 0.9‐11.2℃ in the winter. Furthermore, by integrating the EAHEs in a building design, one can reduce the total annual cooling load by 1.25%‐3.97% and for heating by 1.34%‐3.96%. The payback period of the system with a pipe length of 25 m is 16 years, but for the systems with pipe lengths of 50 and 75 m, this period reduces to almost 3 years.

Highly oscillatory integrals are frequently involved in applied problems, particularly for large-scale data and high frequencies. Levin method with global radial basis functions was implemented for numerical evaluation of these integrals in the literature. However, when the frequency is large or nodal points are increased, the Levin method with global radial basis functions faces several issues such as large condition number of the interpolation matrix and computationally inefficiency of the method, etc. In this paper, the Levin method with compactly supported radial basis functions is proposed to handle deficiencies of the method. In addition, theoretical error bounds and stability analysis of the proposed methods are performed. Several numerical examples are included to verify the accuracy, efficiency, and well-conditioned behavior of the proposed methods.

As people’s living standards are high, the interior design requirements for green ecological residences are increasing. Based on this, the effective application of marine design concept in the design of green ecological residential indoor environment is studied. Firstly, the basic application elements of the marine design concept are analysed, so that under the guidance of the concept of marine design, the optimal design model of the green ecological residential indoor environment is constructed. Through relevant algorithms, the influencing factors of the concept of marine design in the effective application of green ecological residential indoor environment design are tested. The experimental results show that the marine design concept is affected by economic and environmental factors. At the same time , this concept can also be effectively applied to the optimal design of indoor environment of green ecological residence. Ocean design concept is effectively applied in the interior environment design of green ecological residence, which improves people’s living standard.

High efficiency of perovskite solar cell can be obtained through various approaches, including materials and interface engineering, device modification and fabrication techniques. In all approaches, the quality of the perovskite layer has a significant impact on the efficiency of the perovskite solar cell. Antisolvent dripping is widely used in almost all fabrication methodologies to achieve a high-quality perovskite layer. However, in the conventional antisolvent dripping, there are several factors (antisolvent volume, time and point of dripping, etc.) to be strictly followed. Due to these difficult and critical tricks, researchers often get perovskite layers with pinholes, small grains, and wide grain boundaries that deteriorate the performance of the perovskite solar cells. In order to produce perovskite films with large-scale grains, narrow boundaries and smooth surface morphology, a sealed antisolvent-fumigated process is implemented. There is no need to make any substantial efforts to achieve optimal conditions for the fabrication of high-quality perovskite layers using the antisolvent-fumigated strategy. Consequently, the efficiency of perovskite solar cell improves dramatically from 18.65% to 21.45%. Our findings present a new and convenient method for fabricating highly efficient perovskite solar cells.

The energy supply system of Uzbekistan is not well positioned to meet the rapidly rising domestic energy demand of this country. Uzbekistan's current energy supply system is outdated and has very low diversity, as most of its energy comes from natural gas. In addition to producing immense amounts of greenhouse gas and environmental pollution, this situation is untenable considering the eventual depletion of fossil fuel reserves of this country. Uzbekistan's renewable energy sector is highly undeveloped, a situation that can be attributed to the lack of coherent policies for the advancement of renewable power and the low price of natural gas. However, this country has significant untapped renewable potentials, especially wind energy, that can perform a significant performance in the country's power generation plans. Also, producing hydrogen from renewable power can provide a good alternative to fossil fuels and help meet the needs of the Uzbek industrial sector, especially oil, gas, and petrochemical industries. In this study, the suitability of 17 regions in Uzbekistan for wind-powered hydrogen production was analyzed in terms of 16 sub-criteria in four categories of technical, economic, social, and environmental factors. To obtain robust results, the ranking was performed using a hybrid of BWM and EDAS, as well as WASPAS, ARAS, and WSM techniques. The weighting results exhibited the Levelized Cost of Electricity (LCOE), Levelized Cost of Hydrogen (LCOH), and Annual Energy Production (AEP) to be the most important sub-criteria for this evaluation. Nukus, Buhara, and Kungrad were introduced as the top three most appropriate locations for hydrogen development from wind plants. It was estimated that using 2000 kW turbines, a wind-powered hydrogen production plant built in the Nukus region can achieve an annual power output of 4432.7 MW and annual hydrogen output of 71.752 tons.

An API standard drilling fluid was investigated from laminar to turbulent flow conditions using an in-house-built viscometer at speeds from 200 to 1600 RPM. A power-based method was applied to obtain the apparent viscosity and the shear stress of the water-based drilling mud (WBM) in the annulus of the viscometer. Then, a MATLAB optimization program was developed to obtain model parameters for five rheology models integrated in a generalized Herschel-Bulkley-Extended (HBE) model and two widely used 4-parameter models in drilling industry. It is found that the Bingham, Cross, and HBE rheology models have precisely matched the WBM measurements in the viscometer. A generalized Reynolds number was applied to determine the Darcy friction factor although the PL (power law model) and the HB (Herschel-Bulkley model) exhibited a nonrealistic negative shift from the laminar friction factor.

Network intrusion detection systems analyze traffic in a medical IoT system to detect abnormal behaviors. Machine learning and artificial intelligence (AI) algorithms are widely used in designing intrusion detection systems to prevent attacks on a medical IoT system. In this paper, an artificial neural network is employed to detect abnormal behavior in a medical IoT system. The accuracy of the detection depends heavily on the features that are fed into the artificial neural network. Selecting the important and discriminative features of network traffic is a crucial and challenging issue because it has a significant impact on the learning process. In the proposed method, the butterfly optimization algorithm which is a meta-heuristic optimization algorithm is employed to select the optimal features for the learning process in an artificial neural network. The results achieved, 93.27% accuracy, indicate the capability of the butterfly optimization algorithm to determine discriminative features of network traffic data. The proposed algorithm outperformed the decision tree, support vector machine, and ant colony optimization, which was proposed in previous researches for the same goal.

One of the essential steps to design energy conversion-based systems is choosing an efficient working fluid under the design goals to access stable products with high efficiency and overcome environmental issues. In this regard, the current paper is motivated to devise and evaluate a novel geothermal-driven multigeneration system under the effect of various working fluids. The proposed system consists of a flash-binary geothermal power plant, an organic flash cycle (OFC), a power/cooling subsystem (an organic Rankine cycle (ORC) and a thermoelectric generator incorporated with a compression refrigeration cycle), and freshwater and hydrogen production units utilizing a humidification-dehumidification desalination unit and a low-temperature electrolyzer. Considering the design potential of the OFC and ORC, four different environmentally-friendly working fluids, i.e., R123 and R600 in the OFC and R1234yf and R1234ze(e) in the ORC are selected and classified in four groups to introduce the best one, under the energy, exergy, and economic (3E analysis) approaches. Also, the whole system is optimized through a genetic algorithm, respecting the optimal solution for the energy efficiency and unit exergy cost of the products. According to the results, R123/R1234ze(e) shows the highest cooling, hydrogen, freshwater production rates, and energy efficiency. Likewise, the maximum power generation and exergy efficiency belong to R600/R1234ze(e). Moreover, R600/R1234yf has the lowest unit exergy cost of products.

Smart use of clean energy sources for achieving higher performance and designing cost-effective systems is recognized as an essential solution for reducing fossil fuel consumption. In this regard, this study supports a comprehensive evaluation and multi-criteria optimization of a novel poly-generation plant embracing geothermal energy from thermodynamic and thermoeconomic perspectives. Hence, the utilization of modified subsystems and smart use of multi heat recovery processes are projected and appraised. In this regard, the plant consists of a double-flash binary geothermal subsystem, an organic Rankine cycle in combination with an ejector refrigeration cycle considering a zeotropic working fluid (a mixture of pentane and R142b), a heating production heat exchanger, and a proton exchange membrane electrolyzer with the combined production of cooling, heating, power, and hydrogen. The crucial thermodynamic and thermoeconomic variables are investigated against key parameters and concluded that the sensitivity of outcomes is more evident with the variation in zeotropic working fluid composition and the vapor quality at the heating production heat exchanger's outlet. The attained results at the optimum mode demonstrated, the energy and exergy efficiencies of the plant as well as total unit costs of products are as being 44.5%, 35.8%, and 18.8 $/GJ, respectively.

In the present numerical study the ring-shape depressions were created on the wall of spiral pipe that can be employed as a heat exchanger in the solar ponds. Unlike available literature that focused on the optimization of solar ponds through its nature recognition, present study tried to propose an efficient passive method for maximizing heat extraction. This is a simple and cost-efficient technique for enhancing the overall performance of salinity-gradient solar ponds through augmentation of turbulence inside the modified piping system and yielding higher heat extraction accordingly. Indeed, the introduced practical technique not only prevents the increment of size and volume of the piping system but also makes it needless to use additional supplementary equipment like turbulator or even air injectors. Moreover, this is a good way to prevent fouling inside piping system which bears huge costs. 3D numerical simulation was done based on Finite Volume Method (FVM) and turbulent flow simulated by RNG k-epsilon model. Due to the steady-state nature of this problem pressure–velocity coupling algorithm was adopted. The effect of several decisive parameters including Dean, Pr (fluid type and inlet temperature), groove distance, and groove depth on Nu, f, j-factor, and TPF was studied. Interestingly, it was turned out that the values of thermal performance factor (TPF) for all cases were above 1 which shows the justifiability of made modifications. For all flow rates water has the highest Nu and the lowest friction factor compared to Theminol-55 and Ethylene-glycol. Groove pitch of 20 mm makes the highest values of Nu so that 168, 195, and 216 were the maximum obtained Nu for cases with groove depth of 0.7 mm, 1 mm, and 1.3 mm, respectively (working fluid was water and Dean = 1615). Said statement is true for f where its maximum values were 0.1, 0.14, and 0.2, respectively, for cases with groove depth of 0.7 mm, 1 mm, and 1.3 mm (working fluid was water and Dean = 269). The highest Nu of Therminol-55, Ethylene-glycol, and water were 100, 114, and 216, respectively for groove pitch of 20 mm.

This work examines the entropy generation with heat and mass transfer in magnetohydrodynamic (MHD) stagnation point flow across a stretchable surface. The heat transport process is investigated with respect to the viscous dissipation and thermal radiation, whereas the mass transport is observed under the influence of a chemical reaction. The irreversibe factor is measured through the application of the second law of thermodynamics. The established non-linear partial differential equations (PDEs) have been replaced by acceptable ordinary differential equations (ODEs), which are solved numerically via the bvp4c method (built-in package in MATLAB). The numerical analysis of the resulting ODEs is carried out on the different flow parameters, and their effects on the rate of heat transport, friction drag, concentration, and the entropy generation are considered. It is determined that the concentration estimation and the Sherwood number reduce and enhance for higher values of the chemical reaction parameter and the Schmidt number, although the rate of heat transport is increased for the Eckert number and heat generation/absorption parameter, respectively. The entropy generation augments with boosting values of the Brinkman number, and decays with escalating values of both the radiation parameter and the Weissenberg number.

Ventilation is a way of improving the air quality of rooms by circulation. The position of the inlet and outlet greatly influences the thermal comfort. This attempt proposes to analyse the effect of the position of window openings for a room building with natural ventilation and the air flow and temperature distribution numerically using a commercial computational fluid dynamics (CFD) code. This proposed study consists of (i) approving the numerical model against experimental data gathered in an environment similar to the one used in simulations and (ii) applying the CFD model to explore the results of four varying configurations of ventilator on the natural ventilation system and thermal comfort. For the varying arrangements, the wind speed is 0.2 m⋅s−1 perpendicular to the openings for a wind, (iii) evaluating the comfort level utilizing the Air Diffusion Performance Index (ADPI) on the basis of ASHRAE 55-210 criteria. The obtained results show that the positions of outlet and inlet openings highly affect the performance in the thermal comfort while they have a trivial effect on the occupied zone mean velocity. The computational results showed that the two cases (a) and (b) present results very close to each other with a slight difference at the center of the chamber. Most of the calculated values (effective draft temperature, EDT) are between (−1.7 and 1.1). Then ADPI is over 70% for case (a) and over 75% for case (b), so all points they are located in the comfort zone. The results affirmed also that configuration with inlet openings set at 1.022 m above ground and an outlet opening set at 0.52 m brings about the most applicable solution ventilation efficiency and give the best EDT that fulfills the criteria of ASHRAE 55-210 with an ADPI of ~90%.

In the preceding times, the number of enclosed parking garages has increased significantly in developing nations. The toxic emissions from vehicular exhausts are expected to drastically compromise the environmental conditions of the parking garages. Subsequently, exposure of humans to these accumulated pollutants is also expected to degrade their health. Therefore, in the present investigation, efforts were made to estimate the applicability of TiO2-mediated UV photocatalysis in degrading the concentration of vehicular emissions, viz., NOx and SO2, in the enclosed parking garages (EPGs). In this regard, an artificial EPGs’ environment was created and experiments were designed using the Box-Behnken design in combination with response surface methodology. The process parameters chosen for maximizing the degradation of the pollutants were a concentration of TiO2 emulsion (20 to 120 ml/m2), UV irradiance (1 to 5 mW/cm2), and relative humidity (10 to 50%). Optimization of the laboratory experiments revealed that at optimal conditions of the process parameters, i.e., a concentration of TiO2 emulsion = 77.50 ml / m 2 , intensity of UV irradiance = 3 mW / c m 2 , and relative humidity = 43.2 % , maximum degradation of the NOx and SO2, i.e., 61.24% and 55.05%, respectively, was achieved. Further, it was revealed that relative humidity may prove to be the limiting factor while using the TiO2-mediated UV photocatalysis in humid areas. Findings of this study may prove beneficial in urban planning as it may assist scientific auditory and local authorities in identifying the applicability of TiO2-based photocatalysis in mitigating the impacts of vehicular emissions.

Power consumption of wellbore drilling in oil and gas exploitations count for 40% of total costs, hence power saving of WBM (water-based mud) by adding different concentrations of Al2O3, TiO2 and SiO2 nanoparticles is investigated here. A high-speed Taylor–Couette system (TCS) was devised to operate at speeds 0–1600 RPM to simulate power consumption of wellbore drilling using nanofluids in laminar to turbulent flow conditions. The TCS control unit uses several sensors to record current, voltage and rotational speed and Arduino microprocessors to process outputs including rheological properties and power consumption. Total power consumption of the TCS was correlated with a second-order polynomial function of rotational speed for different nanofluids, and the correlated parameters were found using an optimization technique. For the first time, energy saving of three nanofluids at four low volume concentrations 0.05, 0.1, 0.5 and 1% is investigated in the TCS simulating wellbore drilling operation. It is interesting to observe that the lower concentration nanofluids (0.05%) have better power savings. In average, for the lower concentration nanofluids (0.05%), power was saved by 39%, 30% and 26% for TiO2, Al2O3 and SiO2 WBM nanofluids, respectively. TiO2 nanofluids have better power saving at lower concentrations of 0.05 and 0.1%, while Al2O3 nanofluids have saved more power at higher concentrations of 0.5 and 1.0% compared with their counterpart nanofluids.

Behavior of hybrid nanofluid in views of irreversibility and convection was scrutinized in current article. Influences of Lorentz, gravity and permeability on isotherms, components of irreversibility were depicted. With involve of single-phase model, properties of carrier fluid were estimated and related terms of porous zones were added in momentum equations as well as Lorentz forces. CVFEM was applied and new formulations for Nu and Be were offered according to achieved data. The variables are permeability, gravity and Lorentz forces and contours for various values of them were depicted. As Ra and permeability increase the isotherms become more complicated and it means higher convection. Rise of these factors makes velocity of testing fluid to increase. Augmenting Ha acts against the gravity force and velocity reduces. Temperature of inner wall declines about 15% with augment of permeability while it rises 17.65% with augment of Ha. Nu decreases about 19.93% with augment of Ha while it enhances about 80.44% and 7.52% with growth of Ra and permeability. Be declines about 2.82% and 80.3% with augment of permeability and Ra. Also, Be rises about 24.57% with grow of Ha.

In this study, the performance of a system consisting of an organic Rankine cycle (ORC) for generating power and an electrolyzer for producing hydrogen with a zeotropic mixture as working fluid to recover waste heat in a geothermal flash-binary cycle is investigated from energy and exergy point of view. The study also investigates the effect of using zeotropic mixtures with different compositions as the ORC's working fluid rather than pure fluids. Using the particle swarm optimization (PSO) algorithm, the optimization is performed to maximize the power production of the entire system. The results show that using the combination of pentane with other pure fluids as working fluid led to improved system performance in terms of power and hydrogen output. In view of ORC unit power output (31.51 kW), overall system power output (128.16 kW), and hydrogen output (0.39626 kg h−1 per kilogram of geothermal water), the pentane (0.54)/butene (0.46) mixture produces the best results. Under optimal operating conditions, the rate of exergy destruction, exergy and energy efficiency for the whole system is equal to 95.81 kW, 37.25% and 20.17%, respectively. It is also found that the composition of the zeotropic mixture has a significant impact on the performance of the ORC as well as hydrogen production, which is associated with the extent of temperature glide in the mixture. When pentane (0.54)/butene (0.46) is used as the working fluid, the highest improvement related to use of zeotropic mixture instead of pure fluid is observed, which increases the power output of the ORC unit and the hydrogen output of the system by, respectively, 22.53% and 23.02%. In the end, the effect of flash chamber pressure on the total power and hydrogen output is also investigated. This investigation shows that as this pressure increases, the total power output decreases. However, although a lower chamber pressure is more desirable, given the impact on the hydrogen production and the turbine size, it is preferable to keep the flash chamber pressure moderate.

Objective: In this paper, we consider a model that describes the ciliary beating in the form of metachronal waves along with the effects of Magnetohydrodynamic fluid over a curved channel with slip effects. This work aims at evaluating the effect of Magnetohydrodynamic (MHD) on the steady two dimensional (2-D) mixed convection flow induced in carbon nanotubes. The work is done for both the single wall nanotube and multiple wall nanotube. The right wall and the left wall possess a metachronal wave that is travelling along the outer boundary of the channel. Methods: The wavelength is considered very large for cilia induced MHD flow. The governing linear coupled equations are simplified by considering the approximations of long wavelength and small Reynolds number. Exact solutions are obtained for temperature and velocity profiles. The analytical expressions for the pressure gradient and wall shear stresses are obtained. The term for pressure rise is obtained by applying Numerical integration method. Results: Numerical results of velocity profile are mentioned in a table form, for various values of solid volume fraction, curvature, Hartmann number [M] and Casson fluid parameter [ζ]. The final section of this paper is devoted to discussing the graphical results of temperature, pressure gradient, pressure rise, shear stresses and stream functions. Conclusion: Velocity profile near the right wall of the channel decreases when we add nanoparticles into our base fluid, whereas the opposite behaviour is depicted near the left wall due to ciliated tips, whereas the temperature is an increasing function of B and γ and a decreasing function of Φ.

The performance of mass transfer rate, friction drag, and heat transfer rate is illustrated in the boundary layer flow region via induced magnetic flux. In this recent analysis, the Buongiorno model is introduced to inspect the induced magnetic flux and radiative and convective kinetic molecular theory of liquid-initiated nanoliquid flow near the stagnant point. The energy equation is modified by radiation efficacy using the application of the Rosseland approximation. Through similarity variables, the available formulated partial differential equations are promoted into the nondimensional structure. The variation of the induced magnetic field near the wall goes up, and very far away, it decays when the size of the radiation characteristic ascends. The velocity amplitude expands by enlargement in the amount of the magnetic parameter, mixed convection, thermophoresis parameter, and fluid characteristic. The nanoparticle concentration reduces if the reciprocal of the magnetic Prandtl number expands. The temperature spectrum declines by enhancing the amount of the magnetic parameter. Drag friction decreases by the increment in the values of radiation and thermophoresis parameters. Heat transport rate increases when there is an increase in the values of Brownian and magnetic parameters. Mass transfer rate increases when there is incline in the values of the magnetic Prandtl and fluid parameter.

The electro-osmotically driven flow of Casson fluid across a cylindrical geometry with systematically contracting and relaxing sinusoidal walls is mathematically interpreted. The phenomenon of heat transfer also has its worth in the present investigation. The Joule heating and viscous effects are also studied in detail. The mathematically formulated equations that govern the flow of Casson fluid are simplified in their dimensionless form by using lubrication approximation, i.e. ( λ → ∞ ) . Finally, exact mathematical solutions are flourished for these dimensionless equations. The graphical results are presented to further explain the exact solutions of velocity, temperature, pressure rise, pressure gradient, and streamlines pattern. The major outcomes show that electro-osmosis is very helpful in controlling both flow and heat transfer.

A solar air heater (SAH) is a heat exchanger that is capable of converting radiations (solar) into thermal energy, which is further utilized for heating purposes. But due to poor thermal conductivity of air, SAH has poor thermal performance. Roughness is one of the effective techniques used to improve the performance of SAH. Two different roughness geometries, semicircular and square, were used in the present article, and the effect of different parameters on the exergy efficiency of a SAH is investigated. The flow passage used for the solar air heater has a triangular cross section with an equal side length of 160 mm. The positive impact of various roughness parameters (relative roughness height, e/D and relative roughness pitch, p/e) and operating parameters (Reynolds number) has been obtained on the exergetic efficiency of the SAH. Comparing both the roughness geometries, it is concluded that the exergetic efficiency found in semicircular ribbed SAH is 26% higher than that of square roughness at e/D and p/e value of 0.04 and 10, respectively. The exergetic efficiency of a SAH is suitable for design as it includes the quality of useful energy and its associated pumping power. The design plots are also developed and based upon that recommendations are made to develop an efficient solar air heater.

In this study, frequency simulation and critical angular velocity of a size-dependent laminated rotary microsystem using modified couple stress theory (MCST) as the higher-order elasticity model is undertaken. The centrifugal and Coriolis impacts due to the spinning are taken into account. The size-dependent thick annular microsystem's computational formulation, non-classical governing equations, and corresponding boundary conditions are obtained by using the higher-order stress tensors and symmetric rotation gradient to the strain energy. By using a single material length scale factor, the most recent non-classical approach captures the size-dependency in the annular laminated microsystem. Furthermore, by ignoring the length scale element of the material, an annular microsystem’s mathematical formulation based on the classical model can be retrieved from the current model. Ultimately, the governing equations, which are non-classic, have been solved for various boundary conditions (BCs) using the two-dimensional generalized differential quadrature (2D-GDQ) approach. The effects of Young's modulus ratio the, rotating speed, radius ratio, laminated layers’ number, length scale element, and laminated types on the critical rotating speed and frequency responses of the laminated spinning microdisk are then investigated using MCST. The outcomes reveal that the negative influence from spinning velocity on the system’s dynamics is more significant than the negative influence from radius ratio, and the mentioned problem is more considerable for the vertical laminated pattern. Finally, the critical radius ratio and rotating speed increase by changing the laminated pattern from vertical to longitudinal.