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Brush seals are leakage performance systems that are operating against turbine shafts and bucket tips. Flexible bristle structure can compensate the rotor interference during transients, which enables closer clearance control in turbine and turbo-engine applications. During turbomachinery transients, contacting bristles exert force on turbine shaft, which in turn result in wear, frictional heat generation, counter torque and power loss. Brush seal design with proper stiffness has crucial importance since high bristle tip force levels during rotor contact may result in rotor instability, bristle tip melting or thermo-mechanical fatigue due to large amount of local frictional heat input. Counter torque applied by the contacting brush seal with improperly excessive tip force may result in turbine stall and overall efficiency losses. High levels of bristle contact forces may induce elevated wear rates, which degrades the leakage performance of the brush seal during its life cycle. Brush seal contact force evaluation under operating conditions has critical importance and has to be conducted before turbine integration to avoid performance losses and possible turbine failure in some extreme cases. In this paper, ‘Bristle Contact Force Theory’ is developed and closed form bristle tip force (BTF) function is derived where rotor-bristle, inter-bristle and bristle-back plate interactions are included. BTF measurements under pressurized and unpressurized air environment are conducted for the selected test seals by using the custom ‘Rotary Test Rig’. BTF function of bristle contact force theory show high level of correlation with the test data. The effect of cant angle manufacturing tolerance on bristle tip force levels is also examined through bristle tip contact force theory, and compared with the test seal measurements. Methodology for number of bristle row calculation and comparison with the geometric inspection of test seals are also detailed within the content of this paper.

Geological repository of high-level nuclear waste (HLNW), the most feasible approach for the safe and permanent treatment of HLNW without human intervention, has been investigated for years by many researchers. In some countries, real facilities for the geological repository are already under construction. In Japan, however, due to complicated geologic conditions, especially underground water and fractured rock masses, and the high risk of natural disasters, ensuring the long-term stability of the method remains a struggle. The influential factors include underground water, heat generation from radioactive waste, and thermal and chemical weathering of the surrounding rock mass as a natural barrier. It is difficult to estimate and verify the long-term stability for up to one hundred thousand years, a complicated thermal–hydraulic-mechanical-chemical coupling behavior, via any field test. The objective of the study is to develop a numerical method for predicting the long-term stability of geological repositories. As the first step toward realizing this objective, heating and loading tests on cave model made of man-made rock specimens that are composed of diatoms, gypsum, and water, which are viscoplastic materials, were conducted, based on which a newly proposed numerical method with finite element method (FEM) was used to describe the thermal, mechanical, and time-dependent behavior of the model tests for a geological repository. To ensure the accuracy of the numerical calculations, all the material parameters in the thermoelasto-viscoplastic model with consideration of overconsolidation, the structure, and the influence of intermediate stress were determined via triaxial compression/creep tests under various temperatures, confining stresses, and loading rates. Finally, the validity of the numerical method was demonstrated by model tests over a limited time span.

Li-ion battery packs provide high energy density but with a concern of thermal management. Hence cooling mechanism is necessary to have a good life and reliability on the battery system. The main objective of this article is to investigate the effect of conjugate and non-conjugate boundary conditions on battery pack heat transfer characteristics. In conjugate conditions, coolant flow is considered with heat flux continuity at the battery and fluid interface. In non-conjugate condition, just convection condition is adopted. The finite volume method is adopted for the numerical analysis, and a code is written for computations of the governing equations. Effects of different parameters like heat generation, conductivity ratio, coolants, and Biot number on temperature distribution in the battery pack are analyzed. The maximum temperature contours are located near the top end of the battery, whereas at the bottom end, the battery's temperature is low. Such high and low-temperature regions in the battery pack create uneven thermal stresses, resulting in battery failure. To have better performance results for the battery system, one should maintain the proper balance of thermal conductivity between the solid and fluid domains. From comparative analysis it is found that the non-conjugate condition gives the temperature distribution in battery to be of symmetrical nature and more uniform. Practically, this is not true which is confirmed by the realistic conjugate condition where the high temperature zones are closer to the trailing edge of the battery pack. Liquid metals and nanofluids provide a much safer operating temperature of the pack where the maximum temperature is well below the critical temperature. The application of conjugate condition for battery thermal analysis leads to be have an insight of the hotspot zones accurately which are operated using conventional fluids mentioned in this work.

This work reports the fabrication of AuNR@MSNs [i.e., gold nanorods (AuNRs) coated with mesoporous silica nanoshells (MSNs)] with independent sensitivities to pH and near-infrared (NIR) light for reversible on–off switching of drug release without premature drug leakage. The fabrication involves the incorporation of lauric acid (LA) as a thermosensitive gatekeeper, followed by the coating of tannic acid (TA) layers as a pH-sensitive gatekeeper. The protonation–deprotonation of the TA layers according to change in pH can result in their swelling–deswelling to induce pH-sensitive drug release, while the solid–liquid phase transition of LA by NIR light-induced heat generation in AuNRs enables the NIR light-controlled release of preloaded drug molecules. The interplay between these dual gatekeepers allows the release of pre-loaded drug from the AuNR@MSN-LA@TAs (i.e., AuNR@MSNs incorporating LA and TA) only at acidic conditions under NIR light irradiation, without premature drug leakage under inactive conditions (neutral pH or no NIR light). Moreover, the reversibility of the gatekeepers can make an on–off mannered drug release. Benefiting from the capability of the gatekeepers to induce pH-/temperature-sensitive release, along with the photothermal ability of AuNRs, the AuNR@MSN-LA@TAs can exhibit a satisfactory anticancer performance without undesired drug leakage.

In this manuscript a study of the unsteady magneto-hydrodynamic mixed convection Jeffrey fluid flow over an inclined permeable moving plate in presence of thermal radiation, heat generation, radiation, aligned magnetic field, thermophoresis effect and homogenous chemical reaction, subjected to variable suction has been undertaken. The governing equations are solved by using a regular perturbation technique. The expressions for the distributions of velocity, temperature and species concentration are obtained. With the aid of these, the expressions for skin friction, Nusselt number and Sherwood number also have been derived. The influences of various physical Parameters involved in the problem on the above mentioned quantities are discussed with the help of graphs and tables. From the significant findings, it has been found that the velocity increases with an increase in Jeffrey fluid in the presence of permeability. It shows reverse effects in the case of magnetic parameter, radiation parameter and chemical reaction parameter. Comparisons with previously published work performed and the results are found to be in the excellent agreement.

Burgeoning demand for machinability, health, and ecology, Environmental Protection Agency (EPA) regulations are pushing the modern manufacturing sector to apply dry or biodegradable cutting fluids, which are insufficient in the machining of difficult-to-cut materials. Therefore, this study is devoted to proposing a newly developed hybrid ethanol-ester oil lubri-coolant for machining titanium alloy. To encompass the effectiveness of the proposed cutting medium, the thermophysical properties (density, thermal conductivity, viscosity, specific heat), and tribological properties (friction coefficient, friction force), and investigated. Besides, the machinability performance of hybrid lubri-coolant is determined in terms of cutting temperature, cutting force, surface roughness, residual stresses, tool wear through minimum quantity lubrication (MQL) system in the high-speed machining of heat-treated Ti-6Al-4V. The machinability performance of hybrid lubri-coolant are compared to dry cuttings. Findings have depicted that density, viscosity, and thermal conductivity were decreased with the increase of temperature while specific heat was increased with the increase of temperature. Tribological characteristics showed the highest friction coefficient and friction force under dry conditions while minimum under hybrid ethanol-ester oil (1:1) conditions. The hybrid ethanol-ester oil lubri-cooling in milling showed lower cutting temperature, cutting force, surface roughness, residual stresses, and minimum tool wear results. The hybrid ethanol-ester oil is biodegradable, providing efficient cooling with the evaporation of ethanol, and lubrication due to long-chain ester oil molecules. The polar nature of ethanol and ester oil prevented microparticles adhesion and made a tribo-film on the tool-workpiece and prevented rubbing or frictional heat generation.

Internal-cooling method due to its numerous advantages has been used during the machining of hard to cut and difficult to machine materials. Cooling channels developed in the cutting inserts, drills, end mills and grinding wheels are used for the heat removal which is concentrated at a smaller region during machining process. So, these cooling channels play a vital role in decreasing the temperature and wear rate of the tools. The heat generation and transfer rate depend upon the physical configuration of the cooling channel. This research work presents novelty in the concept of developing internal cooling channel cutting inserts with different profiles. Three different profiles have been developed to investigate cooling effect on the turning tool insert with different shapes. The results have been compared with the standard tool having no cooling channel. Computational Fluid Dynamics (CFD) has been used to simulate temperature rise for all profiles. A temperature drop of 188 K has been found for internally cooled cutting insert in comparison to the standard tool having no channel. It has also been found that the temperature difference of range 20 K–88 K can be achieved by varying the profile of the channel. Besides this, an increase in the inlet pressure of the cutting fluid has been found to make the coolant profile more efficient in terms of heat removal. Through the velocity vector results, it has been found that with more flow velocity of coolant inside the channel more heat transfer takes place. Turbulence Kinetic Energy (TKE) results showed that the heat transfer rate can be increased with an increase in the TKE value which in turn depends upon the profile of the coolant flow channel. This CFD study in turn has laid the platform for setting the optimum parameters during the turning of Titanium alloy with internal cooling channels.

When deep hole drilling problematic aluminum materials, the high ductility and adhesion tendency of these materials lead to the formation of built-up edges, long chips and material adhesions on the tool. This can not only cause rapid tool breakage, but also lead to significant damage to the borehole wall surface. In previous work, it has already been shown that these problems were avoided during vibration-assisted drilling with short tools. Compared to conventional drilling, in vibration-assisted drilling the feed motion is superimposed with a sinusoidal oscillation with a high amplitude and a low frequency resulting in a kinematic cut interruption and the generation of separated chips. The aim of this work is to investigate the extent to which the above mentioned problems encountered in conventional deep hole drilling of aluminum materials can be reduced by vibration-assisted deep hole drilling. To achieve this aim, experiments were carried out in conventional and vibration-assisted deep hole drilling. The chip geometry, feed forces, straightness deviation, surface temperatures and the surface quality of the borehole wall were used as evaluation criteria to compare both processes. It was demonstrated that the formation of built-up edges and material adhesions is avoided by vibration-assisted deep hole drilling. This results in a better surface quality of the borehole wall, what indicates less friction within the borehole due to the generation of small and separated instead of long chips. Since heat generation in vibration-assisted drilling is much lower than in conventional deep hole drilling, boreholes close to the workpiece surface were realized.

A coupled optical-electrical-thermal modeling has been developed to investigate the heat generation and dissipation in Cu2ZnSn4SxSe4−x thin film solar cells. Five heat generation factors: Thermalization, Joule heat, Peltier heat, Surface Recombination heat, and non-radiative recombination heat (Shockley-Read-Hall and Auger) as well as two heat dissipation factors convective and radiative cooling were calculated and displayed in 2 and 3 dimensional maps. Thermalization is the dominant heat generation factor in the cell independent of the voltage. The non-radiative recombination heat and Joule heat depend on voltage. Apart from these bulk heating factors, the surface recombination heat and Peltier heat were also investigated. The surface recombination heat is higher at open-circuited voltage (V=Voc) compared to at V = 0 while the Peltier heat is zero at V=Voc which can be explained by looking at the energy band diagrams at these voltages. The total heat generation has a small gradient across the cell thickness (

To avoid thermal necrosis has always remained a challenge during trauma and orthopaedic (T&O) surgeries. Use of different coolants of liquid form like water, saline and gaseous form like Carbon dioxide and nitrogen are frequently used for the same. Though the factors responsible for temperature control related to drilling process like drilling parameters and drill specifications are important, the contribution of coolant in temperature control cannot be underrated. In this review work, the different aspects related to coolant supply like 1) effects of saline and water on different bone defects, 2) comparative effectiveness of internal coolant flow through step drill and conventional drill, 3) effects of irrigation volume and 4) significance of without cooling, external liquid cooling and internal gas cooling on temperature rise is made. The results show that, whereas, carbon dioxide is having specific heat capacity of 0.846 kJ/ kg-K and of nitrogen gas it is1.04 kJ/kg-K and of water it is 4.18 kJ/kg- K. So water solution has an improved cooling capacity than both of the gases CO2 and N2. But gases can be directly injected at the location of chip formation and so they also proved as a worthy alternative.

Machining of difficult to cut material at advanced range of process parameters is the requirement of modern day machining scenario for achieving the goals of sustainable machining through utilization of modern cooling techniques to minimizing the friction, heat generation and tool damage. Consequently, leads to profitable machining under the provision of suitable volume, application method and environmental friendly cutting fluids. Contrary to this, larger flow rate and inferior methodology of cutting fluid application leads to various health problems, environment issues and imperfect product quality. So, to achieve targets the sustainable machining, the firm has to meet certain environmental norms regarding the application and disposal of cutting fluids. Therefore, to tackle the aforementioned ecological issues the dry machining is preferred which exhibit solution, but this option does not endure economic plan at accelerated machining parameter levels due to lower tool life and impaired quality of product. Hence, the alternative to all these situations are the requirement of such a cooling system which does not pollute the environment, operator friendly as well as economical to use. Henceforth, the minimum quantity lubrication using soybean oil has been used in present investigation as a replacement to flood lubrication. The experiments have been conducted on EN-31 Steel taking advanced ranges of machining parameter in dry and M.Q.L system. Research outcomes revealed that the M.Q.L machining improved the surface finish, lowered the cutting temperature and enhanced the chip reduction coefficient with comparison to dry machining system. The Parametric optimization evaluated by TOPSIS approach pointed out that the best machining combination has been observed at 196 m/min, 0.088 mm/rev in vegetable oil environment.

In this paper, the effect of viscous dissipation and Joule heating on magneto-hydrodynamic (MHD) nanofluid flow towards a vertical sinusoidal wavy surface has been investigated numerically. The wavy surface is considered to be heated with uniform flux. Effects of radiation and nanoparticle volume concentration are also considered. The fluid flow over the surface geometry is designed through the highly non-linear partial differential equations, and governing equations must be transformed into a dimensionless non-similar system of equations to get a better solution by applying the highly efficient well-known Keller-box scheme. In this regard, the numerical solutions are obtained for a concentration of mass fluid, velocity profile, temperature profile, local skin friction number coefficient, local Nusselt number, and Sherwood number shown graphically. Connected parameters involve in the modelled problem such as heat generation parameter, radiative conduction flow parameter, the amplitude of the waviness of the surface, Prandtl number, Brownian motion parameter, Buoyancy ratio, magnetic parameter, Thermophoresis parameter and the Lewis number for momentum, temperature profile, and concentration profile of the fluid through different graphs are explained. In this process, certain iterations were performed for different step sizes in the direction of η = 0 . 01 and x = 0 . 005 , respectively. So, keeping this in view to get the more accurate results with all parameters considered, 0 ≤ M ≤ 1 , 0 ≤ R d ≤ 1 , 0 ≤ Q ≤ 1 , 0 . 01 ≤ α ≤ 0 . 04 , 0 ≤ L e ≤ 40 , 0 . 1 ≤ N b ≤ 0 . 7 , 0 . 1 ≤ N t ≤ 0 . 7 , 0 . 1 ≤ N r ≤ 0 . 7 , 0 . 1 ≤ E c ≤ 0 . 4 , 0 . 1 ≤ J ≤ 0 . 4 , . The obtained results illustrate that Nusselt number, Sherwood number, and velocity profile decreases respectively with the increase of waviness amplitude, but skin friction changes its behaviour to wavier. Also, temperature and concentration profiles increase respectively with enhancing the value of the amplitude of waviness. Finally, it is noted that Nusselt number and Sherwood number decrease for higher values of the Brownian parameter. But after a specific value of x, the trend of Sherwood number increases. However, the behaviour of skin friction decreases, but in a precise manner, it remains almost unchanged.

Because the particle shape, size, and spacing in SiCp/Al composites are not constant, the stochastic fluctuation phenomenon of their cutting force is more remarkable than those of continuous materials. This study aims to develop an analytical model of the dynamic cutting force in the orthogonal cutting of SiCp/Al composites. The stochastic models of the particle volume fraction, particle size, and aspect ratio are established. Based on analysing the mechanical mechanisms in different zones and the heat generation mechanisms in the shear and rubbing sources in the cutting process, a dynamic cutting force model is developed for SiCp/Al composites. This model considers the stochasticity of the particle characteristics and the dynamic change characteristic of heat generation. The predicted results yielded the average and maximum relative errors for the tangential force as 7.29% and 9.86%, respectively, and those for the radial force as 7.36% and 10.33%, respectively. Comparison of the analytical and experimental results presents a good agreement. The effects of the cutting parameters and the tool wear on the average cutting force in the orthogonal cutting of SiCp/Al composites are discussed. Moreover, the effects of the particle characteristics on each component of the cutting force are also analysed. In particular, the dynamic cutting force model can accurately present the dynamic fluctuation characteristics of the cutting process of SiCp/Al composites and study the variation tendency of average cutting force. This work provokes more in-depth thoughts of dynamic fluctuation details in the cutting process and provides the guiding significance for industrial SiCp/Al composites machining.

Recently, a polygonal boundary element method (PBEM) has been developed for solving heat conduction problems. In the PBEM, the radial integration method (RIM) is employed to shift the domain and surface integrals in the boundary-domain integral equation into equivalent line integrals, and all the radial integrals are computed by Gaussian quadrature, which may obtain an accurate solution. However, the computation costs much. Therefore, analytical expressions of radial integrals are derived in this paper, concerning four kinds of varying thermal conductivities and two kinds of heat generation functions, aiming at improving the efficiency. Then all the radial integrals in the boundary-domain integral equation can be analytically calculated. Three examples are employed to examine the analytically-integrated PBEM for solving steady heat conduction problems. The results show that the proposed method is accurate, and it is more efficient than traditional PBEM.

Impact of radiation absorption on chemically reactive and heat generating drilling liquids comprising of water-clay, kerosene-clay or engineoil-clay nanofluids flowing through a vertical channel is considered. Applications are found in rig drilling process for the convective transport of constituent materials up to the surface by the fluid. It is presumed that the cold and hot parallel walls are maintained at different uniform temperatures, but with unequal slip factors. One of the slippery heated walls is stationary while the other stretches linearly. The partial differential equations are scaled to ordinary equations in tandem with the physical boundary conditions, and evaluated through homotopy perturbation method. Certification is accredited via data comparison with numerical results using shooting method. Among others, the results of this investigation suggest that the concentration and temperature distributions dip due to larger radiation absorption and viscosity parameters with or without the suction, velocity slips, and the chemical reaction parameters.

With the rapid development of manufacturing industry, the application of motorized spindle is more and more widely, which puts forward higher requirements for the accuracy and failure rate of motorized spindle. However, a large amount of heat will be generated in the working process, which makes the performance of motorized spindle difficult to meet the requirements, so the thermal properties of motorized spindle need to be further studied to make the dynamic behavior better. In this research, first, the characteristics of inner/outer ring curvature radius and oil film thickness were considered in the mechanical analysis of bearing. Second, a new bearing force equilibrium model including the factors of centrifugal force, gyro moment, and ring expansion was established, in which the deformation caused by centrifugal and thermal effect was separated from the deformation caused by Hertz contact, and then the force-displacement analysis was performed. Third, the heat generation and heat transfer of motorized spindle were fully analyzed and detailed based on the thermal network method, and an optimized convective heat dissipation model for bearings was proposed. In addition, the influence of the oil film thickness on the bearing displacement model was discussed. Next, Newton-Raphson method was employed to calculate the motorized spindle network model and the temperature distribution was obtained. Finally, the temperature rise test of motorized spindle was implemented with variable parameters. And the test data were analyzed and compared with the theoretical results, which indicates that thermal network model established in this investigation has a good validity and reliability.

In this study, a new method of microwave-induced discharge over biomass-derived char (i.e., bio-char) spherical carriers was proposed. Bio-char spherical carriers were obtained through rational forming. The discharge intensity and temperature increase under discharge were measured to elaborate the quantitative relationship between microwave discharge and the temperature increase. The effect of bio-char properties on microwave-induced discharge was investigated. The results revealed that discharge achieved the highest electric–thermal conversion efficiency of 61.04%, and the heat generation ratio through the discharge in the initial 10 min was up to 69.08%. The graphitisation degree and transmission depth of microwaves can affect discharge intensity. A critical light intensity inducing hot spot effect exists under different working conditions, and exceeding the critical value led to the hot spot effect and a sudden increase in bed temperature, with a corresponding range of 2.48–5.76 V. The maximum temperature under microwave discharge reached 981 °C, with a heating rate of 376.4 °C/min. The method is potential in the field of value-added utilization of bio-char and microwave-promoted chemical processes.

Manufacturing high precision and high performance parts in aerospace, automotive and medical industries often requires machining of difficult-to-cut materials such as titanium, nickel and hardened alloyed steel alloys. Low productivity and environmental damage are major problems in cutting these materials, which vitally require optimized cooling strategies. High-pressure cutting fluid supply (HP CF) and cryogenic cooling lubrication (CRYO CL) are two of the most effective cooling lubrication approaches to increase tool life, productivity and avoid scrap production. The scientific and knowledge-based application of HP CF and CRYO CL had a pivotal role in improving the machining of difficult-to-cut materials, specifically in milling processes. In this context, the quantification of the cooling and lubrication effect of HP CF and CRYO CL is essential in order to adapt to the fluctuating heat generation at the cutting zone. The novel concept of a soft sensor for the quantification of the cooling and lubrication effect in the milling process is presented in this paper. This soft sensor integrates force measurements and transient temperature data from the process with the help of a mechanical model as well as an inverse temperature model. These models elevate the measured force and temperature signals to heat flows and power in the thermodynamic domain enabling an energy balancing in the real milling application. A telemetry system was used to measure the transient temperature in the milling tool with embedded thermocouples when milling 42CrMo4 and Ti-6Al-4 V in αβ and β conditions. This way the separated cooling versus lubrication effect of high-pressure cutting fluid supply and a single channel cryogenic cooling lubrication based on carbon dioxide (CO2) and oil is investigated and compared with dry machining at various cutting parameters and proceeding tool wear.

Battery thermal management (BTM) is essential to ensure the safety of the battery pack of electric vehicles. For a variety of BTM technologies, the battery’s internal resistance always plays a critical role in the heat generation rate of the battery. Many factors (temperature, SOC and discharge rate) impact on the internal resistance, however, scant research has explored the effect of battery discharge rate on the internal resistance. This study aims to establish a multi-factor dynamic internal resistance model (MF-DIRM) with error compensation strategy to accurately estimate the internal resistance. In the present study, the internal resistance is estimated using the MF-DIRM which fuses three parameters (the temperature, SOC and discharge rate) and the procedures are two-fold: firstly, the coefficients of the binary fourth-order polynomial about the internal resistance with temperature and SOC are obtained, and then the MF-DIRM is built through the cubic spline interpolation algorithm to interpolate these coefficients at different discharge rates. Rather than measure the internal resistance, this model can estimate the internal resistance, and the estimated error does not exceed 10m Ω . Secondly, to further improve the estimation accuracy of MF-DIRM, the error function of the internal resistance is constructed as a binary cubic spline with the temperature and SOC, thereby constructing a model with error compensation strategy. The MF-DIRM combined with error compensation strategy can better estimate resistance under various conditions and the maximum value of estimation error is less than 2.5 m Ω .

For minimizing the operational cost of an integrated hybrid system, which provides electricity, heating, cooling and water of a residential complex, a new energy management method presented here. The proposed energy management method uses the principles of Reinforcement Learning (RL) based on Deep Q Network (DQN) algorithm to find the operational strategy for the hybrid system. Unlike the stochastic presentation of RL with Markov Decision Process (MDP) in literature, a deterministic approach proposed in this study for energy management of a hybrid system. This presented approach does not require online trial and error or historical data of system performance to determine the operational strategy. This developed RL-DQN method used for energy management of a hybrid system with photovoltaic collectors, ET collectors, wind turbines, CHP units, a water heater, a hot water storage tank and batteries. Thus for a residential complex with variable electrical and thermal loads during a year (8760 h), RL-DQN energy management method estimated two unknown variables in operational strategy, i.e., the partial load of the CHP unit and the amount of heat generation by LPG-fueled water heater. The results of RL-DQN energy management also compared with results of two rule-based methods. The results show a reduction of the operating cost to 10983 $/year by RL-DQN which is lower 6.5% and 30.4% than that for two above mentioned rule-based methods. Lower CO2 production (2.8% and 62.8%) also observed in comparison with that for two above mentioned rule based methods. With the proposed EM method, 80.1% of the required electricity supplied with renewable energies and 82.2% of the thermal load supplied without direct consumption of fossil fuels. The benefit of using predicted load and renewable energies of future hours also investigated for EM. Results show that employing the predicted information decrease the operational cost by about 3.5 percent

Biological compact bone tissue is a typical hard-brittle material, which is extremely sensitive to high temperature. For the calculation of bone microgrinding temperature field, most of the known methods are based on the constant heat flux of the average tangential force without considering the ductile grinding characteristics of bone, leading to large calculation error. A semiempirical heat flux theoretical model based on the dynamic grinding force of hard-brittle bone ductile microgrinding is proposed to solve this bottleneck problem. The mechanism of heat generation and consumption in microgrinding zone under ductile removal mode of bone material is studied first, and the probability statistics of effective cutting abrasive number is analyzed. The heat distribution coefficient in grinding zone is calculated, and the semiempirical heat flux model of the ductile removal of hard-brittle biobone material is developed. Microgrinding experiments are conducted to verify the effectiveness of ductile removal grinding heat flux model. The temperatures of different measuring points on the surface of bone samples and micro grinding force are measured. Results show that the theoretical calculation is consistent with the experimental results, with an average error of

Light has attracted significant attention as a promising tool in the biomedical and cosmetic industries. However, little is known about the cytotoxic effects of conventional light sources based on their physical effects such as temperature and luminance. Here, the cytotoxic effects of representative light sources, a light-emitting diode (LED) and an organic light-emitting diode (OLED), were studied with human adipose-derived stem cells (hADSCs). Regardless of the identical light energy conditions, LED group induced a higher apoptotic activity in hADSCs than the OLED group due to its significant heat generation compared to OLED as further demonstrated with heat shock protein family gene expression. Additionally, we further confirmed the effect of luminance by irradiating light from LED and OLED under the same temperature and energy conditions. Increased cell proliferation was confirmed in the OLED group, and a significant expression of intracellular reactive oxygen species was observed in the LED group without showing heat shock protein upregulation. Taken together, the differences in cytotoxicity and cellular response after LED irradiation compared with OLED irradiation can be varied with temperature and luminance control. This study suggests that OLED based device could be an alternative and promising light source for future biomedical and cosmetic applications.

The quantitative assessment of profile damage of square (SQ) and threaded with three intermittent flat faces (TIF) tool pin was appraised and presented for both uncoated and AlTiN coated tools during friction stir passes on AA6061-T6 plates successively after different travel lengths. Significantly lower profile damage with small amount of profile twisting was noted for TIF tool pin as compared to the SQ tool pin owing to lower force and torque, as predicted by finite element (FE) results. For AlTiN coated tools, the pin profile damage reduced significantly due to high wear resistance, hardness and good adhesion of coating with the tool substrate. Significantly lower temperature rise was noted in the AlTiN coated tool compared to the uncoated tool. A mathematical approach to predict the heat generation was presented and predicted temperatures were found in good agreement with FE results. Plastic deformation of sharp corners, adhesion and abrasion wear of flat faces, and initiation of crack near tool pin-shoulder interface was noted in uncoated tools however, they got reduced in the AlTiN coated tool. The delamination of coating near the tool pin edge, flat surfaces and near the tool pin-shoulder interface was noted due to dislodging of adhered work material. Fairly uniform tensile strength and flexural load were obtained after different weld lengths for AA6061-T6 FSW joints prepared with the AlTiN coated TIF tool pin.

Metal cutting causes severe friction and heat generation in the machining zone. Previously, petroleum-based cutting fluids were applied for reducing friction and machining temperature at the machining zone. Nowadays, nano-cutting fluids are preferred owing to their higher thermal conductivity and better lubricating ability. However, during machining of hard materials (hardness, ≥50 HRC), the effectiveness of these nano-cutting fluids is limited, as they rarely reach to the cutting edge of cutting tool because of high normal stresses. In this regard, the combination of rake face micro-textured cutting tool with indigenously synthesized nano-green cutting fluids under in-house developed minimum quantity cutting fluid (MQCF) environment is accomplished for hard machining experiments. For comparison, hard machining experiments are also performed under dry machining, green cutting fluid and nano-green cutting fluid (NGCF) with untextured cutting tools. Detailed analysis shows significant improvement in hard machining performance using combination of micro-textured tools with NGCF corresponding to forces, chip-tool interface friction, workpiece surface roughness and chip morphology. It is attributed to better infiltration of NGCF in-between chip-tool interface by virtue of micro-textures present on the cutting tool rake face. Further, the proposed analytical model captures the effect of textures on the tool surface in the same way as reduced contact tools. It is in a good agreement with corresponding experimental cutting forces.

Chamfered inserts have found broader applications in metal cutting process especially in high-performance machining of hard-to-cut materials for their excellent edge resistance and cutting toughness. However, excessive heat generation and resulting high cutting temperature eventually cause severe tool wear and poor surface integrity, which simultaneously limits the optimal selection of machining parameters. In the present study, an analytical thermal–mechanical model is proposed for the prediction of the three-dimensional (3-D) temperature field in cylindrical turning with chamfered round insert based on a modified slip-line field approach. First, an innovative discretization method is introduced in a general 3-D coordinate system to provide a comprehensive demonstration of the irregular cutting geometry and heat generation zones. Then, a plasticity-theory-based slip-line field model is developed and employed to determine the intensities and geometries of every elementary heat sources in Primary Deformation Zones (PDZ), Secondary Deformation Zones (SDZ) and Dead Metal Zones (DMZ). At last, a 3-D analytical model is suggested to calculate the temperature increases caused by the entire heat sources and associated images. The maximum cutting temperature region predicted is found existing upon the chip-tool contact area rather than the tool edge. Moreover, the rationalities of cutting parameters employed are analyzed along with theoretical material removal rates and ensuing maximum cutting temperatures. The results indicate that the cutting conditions with large depth of cut and high cutting speed are more desirable than those with high feed rates. The proposed models are respectively verified through a series of 3-D Finite Element (FE) simulations and dry cutting experiments of Inconel 718 with chamfered round insert. Satisfactory agreement has been reached between the predictions and simulations as well as the measurements, which confirms the correctness and effectiveness of the presented analytical model.

Nowadays flux switching machines (FSMs) offer important role in various high torque applications. In these machines, the flux sources such as field excitation coil (FEC), armature winding and permanent magnet (PM) are located in the stator while leaving the rotor part as winding less. However, FSMs with single stator associate with limited free space for active sources in stator, which leads to some drawbacks of complicated structure, less path for flux flow, flux cancellations, heat generation and demagnetizing effects. To overcome this issue, FSMs using double stator (DS) have been proposed by many researchers which provide more free space for active sources and flux to flow. Therefore, in this paper design and performance of DS FSMs with various excitation sources such as field excitation FE FSMs, PM FSMs and hybrid excitation HE FSMs are reviewed. All the highlighted insights and recommendations of this review will hopefully lead to increasing efforts towards the development of advanced DS FSMs for various applications.

As the power consumption and heat generation of electronic devices continue to increase, higher demands are being placed on thermal management materials for heat dissipation. Graphene has been widely used as a thermally conductive filler to improve the thermal conductivity of polymers. However, the poor dispersibility of graphene nanoplates in polymers dramatically limits their practical use in thermal management. A promising strategy to increase the thermal conductivity of polymer composites is to construct interconnected three-dimensional graphene networks. This review summarizes the recent advances in the construction and applications of three-dimensional graphene-based polymer composites and ways to improve their thermal conductivity. The current challenges and prospects for the preparation and applications of these materials are considered.

This research work highlight the newly developed concept of Rosseland approximation and gyrotactic microorganisms in steady, two-dimensional, incompressible flow of Walter's-B nanofluid (non-Newtonian) over a stretchable surface of sheet. Buongiorno nanofluid model, which represents seven important slip mechanisms (i.e., Brownian motion, inertia, Magnus impact, thermophoresis, diffusion-phoresis, gravity and fluid drainage) is utilized in the mathematical modeling of governing expressions. In this research work, only two important factors of seven slip mechanisms (Brownian diffusion, thermophoresis) are studied and the rest of neglected. Furthermore, the Rosseland approximation and heat generation/absorption effects are used in the modeling of the energy equation. The behavior of thermal and solutal stratification effects are addressed at the stretched boundary of the sheet. The nonlinear dimensional flow expressions lead to dimensionless ordinary equations through appropriate similarity transformations. The total residual error is calculated through Homotopy Analysis Method (HAM) for the momentum, temperature, concentration and motile density. The influences of important flow parameters of the governing flow equations are discussed and plotted graphically. The obtained results are compared with fruitful and valuable research in the literature and found very good agreement with them. Over obtained outcomes highlight that the velocity field, declined versus higher estimations of Weissenberg number. It is also remarked that the temperature and concentration fields have contrast impact subject to thermophoresis parameter. The physical quantities like skin friction coefficient, motile density, concentration and Nusselt number are discussed physically via various flow parameters.

Background Glenoid loosening is the most common complication of total shoulder arthroplasty (TSA) resulting in revision. Inaccurate reaming and thermal osteonecrosis from heat generated during the reaming process may contribute to TSA failure by creating a suboptimal bone-implant interface for osteointegration. This biomechanical study investigated the differences in depth penetration and heat generation of used community glenoid reamers in comparison to brand new reamers by using a clinically relevant force. Methods A MTS Servohydraulic machine was utilized to test new and used community glenoid reamers by applying the clinically relevant force of 54.7 N over a defined time. The depth of penetration was measured via the MTS machine and the thermal profile was obtained via an infrared camera. The used reamers were then set by the MTS machine to reach the same depth as the new reamers for all respective sizes while recording the force differential generated and capturing the thermal profile. Levene's F test for variance and a Welch t test for scale variables were performed via SPSS Statistics 24 software. Results At a constant force and time, the new reamers penetrated a greater depth (4.18 ± 2.17 mm) than the community used reamers (0.41 ± 0.22 mm), a difference of 3.80 mm ((95% CI, 2.23 to 5.31 mm), P Conclusion The sharpness of glenoid reamers varies in the community. In order to reach the necessary depth for adequate fixation of implants, orthopedic surgeons may be required to exert a substantially larger force when using dulled reamers in comparison to sharp reamers. As a consequence, the heat generated could increase the risk of thermal osteonecrosis resulting in glenoid loosening. To minimize these risks, strategies may be employed to measure reamer wear, track reamer usage for exchanges, or develop disposable reamer systems. Level of evidence Basic Science Study; Biomechanics

A system analysis of energy production was performed comparing the system of photovoltaic panels and parabolic trough collectors with a hybrid absorber. The paper presents new design of hPTC-CPV absorber. The analysis includes a comparison of the performance of both technologies in different irradiance conditions over the year. The technologies were compared for the same active surface hPTC-CPV and PV. The analysis was performed for a single-family house based on its demand for heat, electricity, and cooling. The calculations are intended to show to what extent an analyzed renewable technology can cover the demand for particular types of energy. The analysis was carried out to assess the legitimacy of using hybrid radiation absorbers in a temperate climate. Hybrid absorber studies were performed using CFD software. The results show that the proposed technology can compete with a PV system in terms of cooling and heat generation. Hybrid absorber covers 74.7% of heat demand for absorption cooling. PV panels with a heat pump cover 44.3% of the heat demand, PV panels with electric heaters 24.3% and hPTC-CPV absorbers 23.3%. The proposed technology cannot compete with PVs in terms of electricity production. Hybrid absorbers cover 8.2% when PVs 71.9% of electricity demand.

Photothermal therapy (PTT) has emerged as a promising therapeutic approach for tumor control and ablation. Attention has focused on exploring advanced organic photothermal agents (OPTAs), with advantages of easy modification, adjustable photophysical and photochemical properties, good compatibility, and inherent biodegradability. However, few detailed studies on how to maximally channelize nonradiative heat generation from the viewpoint of the photothermal conversion mechanism have been reported. Thus, here we assimilate and elaborate on several available action mechanisms to maximize the photothermal conversion efficiency (PCE) of organic dyes. Moreover, we also propose several potential challenges that require substantial future work to address.

Helical milling is applied to the machining of CFRP owing to its favorable characteristics such as low cutting forces and heat generation. However, the prediction of helical milling forces remains a problem in CFRP processing. In this study, a novel predictive cutting force model of helical milling for unidirectional CFRP was established. Based on the cutting parameters, the dynamic cutting angle for the fiber and the corresponding cutting states of the fiber during the cutting process were analyzed, and the number and length of cutting edges involved in cutting were calculated. Then, the cutting forces on the cutting-edge micro-element of the periphery edge and bottom cutting edge under two different cutting states were calculated by treating the fiber as an equivalent homogeneous material. The cutting force prediction model was obtained by taking this into consideration. Finally, the helical milling experiment for unidirectional CFRP was carried out. The results show that the model can effectively predict the cutting force.

Concentrated photovoltaic (CPV) has been identified as an effective method to further enhance the efficiency of photovoltaic cells. Previous studies on CPV mainly focused on III-V multi-junction cells. Nevertheless, III-V CPV technology is mainly used in niche applications due to its high cost. Here, we use metal-halide perovskite solar cell (PSC) to demonstrate a concentrated photovoltaic-thermoelectric tandem device. The thermoelectric generator (TEG) is utilized to reduce the effect of heat generation under concentrated solar irradiance. Our tandem system achieved a peak power conversion efficiency (PCE) of 25.0% at a solar concentration of 3 suns. This efficiency exceeded that of the single PSC by ~4.7%. Our work proves that by controlling the heat flow in concentrated PSC-TEG tandem system, the redundant heat produced by upper PSC can be effectively reused. This tandem structure provides a promising approach to improve the efficiency and stability of PSC under low-concentrated solar irradiation.

Aluminum-Steel joining is an example of a multi-material design. An amalgamation of both the material is very beneficial, yet they pose their set of difficulties in joining due to a significant difference in properties. Solid-state joining processes such as friction stir welding are beneficial in avoiding fusion and formation of a thick intermetallic layer in the Al-steel joint. Critical control of process parameters and tool geometry is essential in friction stir welding to attain a reasonably sound joint. In present work, butt welding of low carbon steel with Aluminum 5052 alloy is performed with the use of three different tools. Progressive refinement in the geometry of tools was done to achieve the optimized dimensions of the tool. The weld joints obtained from various tools were compared based on heat generation. The joints were characterized based on peak temperature achieved, tensile strength, and the number of steel fragments in the Al matrix through micrographs. The weld joint was observed under an optical microscope and Field emission scanning electron microscope (FESEM) for quantification of intermetallic compounds (IMC) layer. Energy-dispersive X-ray spectroscopy (EDX) and XRD analysis were performed to investigate the phase and composition of the IMC layer. The fractured surface under tensile loading was observed under high magnification scanning electron microscope. The tool with a shoulder diameter of 13 mm and a cylindrical pin was found to be optimized for its minimum heat generation and strongest weld joint formation with a minimum number of void-causing steel fragments.

Coaxial one-side resistance spot welding (COS-RSW) is an advanced technique for joining CFRP/metal dissimilar materials. In the present work, a three-dimensional model was developed based upon an in-house finite element code JWRIAN-SPOT to simulate the multi-physical process of the COS-RSW. The thermal cycle and joining strength of COS-RSW joints with different welding parameters were measured experimentally. The sensitivity of material properties of electrode couple and component of accumulated heat generation were discussed in detail. The predicted thermal cycles presented a reasonable agreement with measurements, which also explained the influence of welding parameters on temperature field. The joining strength of COS-RSW joints can be evaluated qualitatively via the area of effective molten zone, which reached about 20 MPa with a 4800 A welding current. The column and cylinder electrodes determined the peak value of interface temperature and molten zone area, respectively. The cylinder electrode was suggested to be fabricated by a high resistivity material to generate sufficient Joule heat. Moreover, the SUS304 electrode and its contact zone provided more than 70% of the entire heat generation. The materials of electrode couple should be determined carefully when employing COS-RSW for joining CFRP and other metals.

Layered Ni-rich LiNixMnyCo1-x-yO2 (NMC) materials are the most promising cathode materials for Li-ion batteries due to their favorable energy densities. However, the low thermal stability typically caused by detrimental oxygen release leads to significant safety concerns. Determining the pathways of oxygen evolution reaction is essential, as the ideal safety countermeasure is to break the reaction chain of thermal runaway. In this study, we demonstrate that two endogenous pathways of oxygen involved in strong exothermic reactions lead the NMC811|graphite pouch cell to an uncontrollable state, and we quantify the individual contribution of the pathways to thermal runaway. Approximately 41% of thermal-induced oxygen reacts aggressively with ethylene carbonate (EC) at the cathode/electrolyte interface with 16% heat generation, accelerating the self-heating rate and thereby further triggering thermal runaway. The residual oxygen that survives the reaction with carbonate spreads to the lithiated anode with major heat generation (65%), bringing the battery to the maximum destructive temperature during thermal runaway. By confirming the significant roles of EC and anode, a deeper understanding on battery fire was achieved. The revealed mechanism can help guide studies on stopping the two reaction pathways, allowing for the safer use of high-energy lithium-ion batteries in the future.

The presently employed synthetic cutting fluids in machining applications lead to skin irritations, hazardous aerosols, ingestion etc., to the machine tool operators. Accomplishing sustainable green machining through bio-cutting fluids, is the key motivating factor behind this work, even though the phenomenon of heat generation is inevitable in the machining process. In the present investigation, Citrullus lanatus extract is chosen as a potential candidate for bio-cutting fluid, since it offers multiple benefits such as increased tool life, cleaner production atmosphere, efficacious heat dissipation, healthy operating conditions, etc. Hybrid LM0-6SiCp-4Grp composite is selected for study since; it has potential applications in marine, aerospace, defence and automotive sectors. Experimentation is carried out with Citrullus lanatus extract as bio-cutting fluid in turning of hybrid LM0-6SiCp-4Grp composite under different processing conditions. The presence of green solution based on Citrullus lanatus extract curtails the rise of temperature significantly during turning operation. Higher magnitude of temperature decrease is observed when the percentage of the concentration of Citrullus lanatus extract is increased, irrespective of depth of turning. Bio-nature and cooling qualities of this green-cutting fluid can contribute its share for green machining and sustainable turning environment. The investigations are further progressed using machine learning algorithms based on the different categories of logical regressions implemented through the Python program. Random forest regression shows better results with 99.8% prediction accuracy compared to other machine learning approaches and the decision tree is constructed through the respective regression model. Decision tree has the ability to handle process parameters systematically and predicts the implications of Citrullus lanatus extract in decreasing the temperature at machine-tool interface during machining operation. This tree structured analysis provides a better inference that delivers flexibility in turning parameters and opens up wider options for operation. Thus, decision tree approach ensures optimized usage of production resources and increases the production capacity through judicial selection of cooling approaches associated with the turning process.

The paper presents an experimental investigation of a solar dish concentrating system with thermal collectors, along with a numerical investigation of a solar cooling installation based on such system by means of dynamic simulation. The main aim of this study is the analysis of heat generation from the system for heating and cooling purposes, with the use of sorption chillers. A computer simulation of the dynamic operation of the proposed solar heating and cooling system was developed within TRNSYS software. The experimental data were used to validate the model of the concentrator and solar collectors. Successively, a solar heating and cooling installation for a residential application, integrating the different configurations of solar energy collecting devices and thermally driven chillers, was proposed and dynamically simulated. Flat-plate, evacuated tube and photovoltaic-thermal collectors were considered along with absorption and adsorption chiller units. In the present study, different system configurations, localities and time bases were considered to investigate the energy and economic performance of the system. The model of the solar dish and collector arrangement overestimates the produced energy by less than 5% as compared to the experimental study. The results show that the space cooling demand is matched in 23.6 and 46.2% by solar energy in Warsaw, while in Lisbon from 38.2 to 46.1%. The simple payback period of the investigated system configuration was for Warsaw between 18.1 years for the combination of flat-plate collector and absorption chiller and 27.2 year for the photovoltaic-thermal collector with adsorption chiller.

Miniature ball-end diamond wheels are widely used for bone grinding in endoscopic surgeries. During bone grinding, a considerable amount of heat is generated, which can cause thermal injuries to the tissues adjacent to bone, including nerves. In our previous studies, it was revealed that the strong adhesion of bone chips on the wheel surface promotes heat generation. To prevent adhesion, a surface-treated wheel was proposed, and it reduced the temperature elevation. However, we found that the proposed wheel cannot stably suppress the temperature elevation because the wheel effect depends on the coolant supply rate. In this study, a bone grinding method that stably suppresses temperature elevation was investigated. Based on the obtained findings, a cooling method using cold air was developed, and the temperature elevation was stably suppressed under a cold air supply.

The paper investigates the basics for increasing the productivity of gas-phase catalytic oxidation processes effected in multi-tubular reactors due to their operation at more concentrated feedstock. Obviously, an increase in initial concentration of the oxidizable reagent seems very attractive, but it is associated with the need to modify the process parameters and/or technological chart in order to achieve the required performance figures. This often entails excessive formation of by-products and therefore overheating of the catalyst bed due to increased heat generation. The cumulative effect of many factors can prevent attaining an acceptably high conversion of feedstock and the yield of target products within a reasonable size of a multi-tubular reactor. The problems we studied are quite typical for highly exothermic catalytic oxidation processes, but are not widely discussed in the literature. On the example of nicotinic acid (NA) synthesis in multi-tubular reactor, we investigated the advantages of the process with elevated feed load (β-picoline), in comparison with the conventional conditions. On the basis of comprehensive process simulation supported by the experimental evidence, for the first time we have shown how the process should be operated to achieve a significant progress in the reactor performance and the target product yield. Our theoretical study showed that the rise in the initial β-picoline concentration from ∼0.8 to ∼3% accompanied by a relevant adjusting of the process parameters leads to a dramatic 1.5–2-fold gain in the specific productivity of catalyst; this could greatly improve the reactor capacity. Optionally, a given production capacity of multi-tubular reactor may be ensured by ∼2 times less number of tubes. Thus, the synthesis of NA at elevated initial feed of β-picoline shall be significantly enhanced in comparison with the conventional process.

A common technique of enhancing thermal conducting is through the insertion of small magnetic particles or other nanoparticles with high thermal conductivity. In this research letter, manganese Zinc ferrite (MnZnFe2O4) and Nickle Zinc ferrite (NiZnFe2O4) were examined to assess the maximum possibility of enhancing thermal conductivity for current heat dissipation fluid problem. Therefore, a mathematical modeling is developed for steady, incompressible, 2D ferromagnetic hybrid (Manganese Zinc Ferrite, Nickle Zinc Ferrite) nanomaterial of micropolar fluid (non-Newtonian) towards moving surface of sheet. Darcy–Forchheimer porous medium effect is studied through momentum equation and thermal stratification effect is employed in heat equation. Micro-rotation and spin gradient effects are accounted. The model of heat diffusion initiated by Fourier law of heat conduction is implemented for energy transport assessment. The governing partial differential equations are altered through implementation of appropriate similarity variables into ordinary ones. Built-in-Shooting technique leads to the solutions of dimensionless flow equations. Behaviors of physical phenomenon are sketched by taking various positive estimations of concerning material constraints. The comparative solutions subject to manganese Zinc ferrite (MnZnFe2O4) and Nickle Zinc ferrite (NiZnFe2O4) hybrid nanofluids are presented and studied. From obtained results, we observed that velocity is more for MnZnFe2O4-NiZnFe2O4-C8H18 as compared to MnZnFe2O4-NiZnFe2O4-C10H22-C8H18 hybrid nanomaterials.

Development of marine engines could largely benefit from the broader usage of methanol and hydrogen which are both potential energy carriers. Here, numerical results are presented on tri-fuel (TF) ignition using large-eddy simulation (LES) and finite-rate chemistry. Zero-dimensional (0D) and three-dimensional (3D) simulations for n-dodecane spray ignition of methanol/hydrogen blends are performed. 0D results reveal the beneficial role of hydrogen addition in facilitating methanol ignition. Based on LES, the following findings are reported: 1) Hydrogen promotes TF ignition, significantly for molar blending ratios βX = [H2]/([H2]+[CH3OH]) ≥0.8. 2) For βX = 0, unfavorable heat generation in ambient methanol is noted. We provide evidence that excessive hydrogen enrichment (βX ≥ 0.94) potentially avoids this behavior, consistent with 0D results. 3) Ignition delay time is advanced by 23–26% with shorter spray vapor penetrations (10–15%) through hydrogen mass blending ratios 0.25/0.5/1.0. 4) Last, adding hydrogen increases shares of lower and higher temperature chemistry modes to total heat release.

The simultaneous transport of momentum, dust particles and heat energy is modeled in form of nonlinear problems via conservation equations. The numerical simulations are performed by implementing finite element method (FEM). The numerical experiments are performed as a function of physical parameters. The relaxation phenomenon and its role in transportation of momentum and heat energy is investigated and an enhancement of transport of heat energy in Maxwell fluid. The velocity of fluid is an increasing function of mixed convection parameter while via hybrid nanostructures Buoyancy force assists the flow. Further, fluid velocity interaction parameter plays a key role in decelerating the flow of fluid with mono and hybrid nano-structures. The ratio of specific heat parameter plays a key role in reducing the temperature of dust particles. Momentum relaxation time determines memory effects and restoration of original state of fluid causes a significant role for decreasing the flow of fluid and hence boundary layer thickness.

The investigation of radiation-absorption, chemical reaction, Hall and ion-slip impacts on unsteady MHD free convective laminar flow of an incompressible viscous, electrically conducting and heat generation/absorbing fluid enclosed with a semi-infinite porous plate within a rotating frame has been premeditated. The plate is assumed to be moving with a constant velocity in the direction of fluid movement. A uniform transverse magnetic field is applied at right angles to the porous surface, which is absorbing the fluid with a suction velocity changing with time. The non-dimensional governing equations for present investigation are solved analytically making use of two term harmonic and non-harmonic functions. The graphical results of velocity, temperature and concentration distributions on the analytical solutions are displayed and discussed with reference to pertinent parameters. It is found that the velocity profiles decreased with an increasing in Hartmann number, rotation parameter, the Schmidt number, heat source parameter, while it increased due to an increase in permeability parameter, radiation-absorption parameter, Hall and ion slip parameters. However, the temperature profile is an increasing function of radiation- absorption parameter, whereas an increase in chemical reaction parameter, the Schmidt number Sc or frequency of oscillations decrease the temperature profile on cooling. Also, it is found that the concentration profile is decreased with an escalating in the Schmidt number or the chemical reaction parameter.

Butt friction stir welding between pure copper and AA5754 alloy was carried out. Reinforcing SiC nano- particles were utilized in friction stir welded (FSW) joints to decline the harmful effects of intermetallic compounds. Tensile tests, micro-hardness experiments, scanning electron microscopy and X-ray diffraction analysis were applied to studying the properties of welded joints. The joints with a travel speed of 50 mm/min and a rotation speed of 1000 r/min showed the best results. The presence of nano-sized SiC particles reduced the grain size of aluminum and copper in the stir zone (SZ) from 38.3 and 12.4 μm to 12.9 and 5.1 μm, respectively. The tensile strength of the joint in the presence of reinforcing SiC nano-particles was ~240 MPa, which is ∼90% of that for the aluminum base. Furthermore, the highest microhardness of the weld zone was significantly increased from HV 160 to HV 320 upon the addition of SiC nano-particles. The results also showed that raising the heat generation in FSW joints increased the amount of Al4Cu9 and Al2Cu intermetallic compounds.

Mobilized-Thermal Energy Storage (M-TES) systems, are an attractive alternative solution to supply heat to distributed heat users by recovering and transporting the low-temperature industrial waste heat (IWH) by vehicular means, have the potential to reduce both the CO2 emissions and costs of energy consumption and lead to more efficient industrial activities as well as improve the quantity of low-carbon energy consumed for heat generation in the residential sector. This paper provides a state-of-the-art review of Phase Change Materials (PCM) applied in M-TES systems. The concept of the M-TES system is briefly described and summarized, including available IWH sources, heating and cooling facilities (for distributed end users), and the main features of two different types of M-TES containers. Recent research achievements in the field have been reviewed, focusing on developed prototypes, experimental and numerical studies, and economic and environmental evaluations. Finally, the barriers to the application of M-TES and possible solutions are discussed. The review highlighted that direct-contact M-TES storage systems can have up to 60% shorter charging and discharging periods when compared to indirect-contact M-TES storage systems with similar storage capacities. Using heat transfer enhancement techniques such as graphite additives, the charging and discharging period for indirect-contact M-TES container can be shortened by up to 74% and 67%, respectively, and that the charging time of direct-contact M-TES can be reduced by up to 29%. The use of M-TES to provide heat can significantly decrease the primary energy requirement, exergy losses and the CO2 emissions by up to 95%, 60% and 93%, respectively, compared to conventional heating facilities using fossil fuels. Recommendations for future research are presented, providing insights of where the current research in the M-TES field is heading and highlights the key challenges that remain to be resolved.

In underwater friction stir welding (UFSW), the thermal conditions between the tool and the plasticized polymeric materials and the relation between glass transition temperatures remain unclear. In this work, a developed coupled 3D thermo-chemical-mechanical numerical model was applied to simulate the UFSW process of polymeric materials. A computational fluid dynamic analysis was conducted for the evolution of the pressure, viscosity and temperatures properties on submerged situation. The numerical model is able to prediction of shrinkage percentage and formation of air gap on the joint stir zone (SZ) by evolution of the mixed slipping/sticking contact conditions at tool/workpiece interface. The simulation results were validated with experimental data on polycarbonate (PC) polymer. It was found that, higher cooling capability of water leads to lower heat concentration on the joint line and consequently, during traverse movement of UFSW tool, the materials viscosity in the leading edge was higher than FSW case. Higher viscosity materials caused the ∼6.8 % lower heat generation and smaller SZ at UFSWed sample. It is shown that the material stirring in FSW joint is higher than UFSW that leads the higher shrinkage percentage and air gap formation. On the other hand, the immersing situation caused the water droplet diffuse into SZ of the UFSW sample. The crystallinity and chemical structural changes of PC in submerged situations were lower than conventional FSW joint, and consequently, the tensile properties and hardness of the welded sample improves in UFSW joint.

In order to safely, efficiently and economically remove the blockages of natural gas hydrate (NGH) in the wellbores of ultra-high pressure gas wells, this paper utilized the heat released from an independently developed autogenetic heat based solid blockage remover through chemical reaction in the wellbore to dissolve NGH and prevent it from forming again. In addition, adjustable heat generation time and heat generation amount was realized by regulating the dosage of the blockage remover. Finally, the chemically autogenetic heat based blockage removal technology was applied to remove the blockages in ultra-high pressure sour gas wells in the Sichuan Basin. And the following research results were obtained. First, when the independently developed chemically autogenetic heat based solid blockage remover is adopted, the peak temperature (34.2–88.5 °C) and time (24.2–884.0 min) of heat generation can be adjusted by its dosage. What's more, there is NGH inhibitor in the reaction product, which can inhibit the regeneration of NGH. Second, as the concentration of the blockage remover increases, the heat transfer speed increases, leading to an increase of NGH dissociation rate around the blockage remover. Third, blockage removal time increases with the increase of wellbore ID. In addition, the increasing rate of the blockage removal time as the wellbore ID increases from 64 mm to 76 mm is lower than that from 76 mm to 102 mm. Fourth, the coincidence rate between the simulation calculation result of heat diffusion and the on-site actual consumption is more than 85%, which indicates that the proposed model for the heat diffusion of chemically autogenetic heat based blockage remover is reliable and can be used to calculate the dosage of blockage remover. Fifth, solid reagent adding device with resistance to sulfur and pressure of 140 MPa is used to add autogenetic heat based solid blockage remover. This blockage remover has been applied in the ultra-high pressure sour gas wells in the Sichuan Basin three well times. Thanks to its application, NGH blockages in these wells are removed successfully and their production is resumed smoothly. In conclusion, this blockage removal technology has such advantages as effective blockage removal, safe and simple on-site operation and low cost, and a promising application prospect.

A model of combustion of aluminum nanopowder in water vapor has been analyzed with allowance for the formation of a condensed phase of aluminum oxide on aluminum particles. Various processes affecting the growth rate of the oxide coating have been considered including adsorption and surface diffusion of Al2O3 molecules on aluminum particles, and condensation of the molecules on the oxide coating. Model calculations have yielded the time profiles of system temperature, phase and fractional composition, as well as the shape of oxide coated aluminum particles. The heterogeneous processes forming the condensed phase of aluminum oxide on Al particles have shown to increase heat generation in the system. On the other hand, shielding aluminum particles by oxide coating retards aluminum evaporation. The competition of these processes during the formation of oxide coating is one of the factors affecting the combustion of aluminum nanopowder in water vapor.

In the present work, the geothermal resources of the Gulf of Suez (GOS) were investigated using category of integrated datasets (i.e., well logs, earthquake events, geochemical and biological indicators). The earthquake data show that the focal depth range of 5–50 km is strongly consistent with the distribution of geothermal anomalies. The temperature profiles show low-to-regular geothermal regimes in many places, ranging from 17.0 to 30.0 °C/Km; meanwhile a higher temperature gradient (>42.30 °C/Km) was recorded in geothermally active areas. The estimated heat generation values from the gamma ray and density logs are as low as 1.50 mW/m3, indicating minor contribution of radioactive decay to the geothermal potentiality. The physicochemical and biological parameters clarified that the thermal water conditions were selective. The subsurface conditions in terms of reservoir temperature and heat flow were determined using geo-thermometers, and found to be 96.33, 81.71 and 85.57 °C and 123.86, 102.12 and 107.83 mW/m2 for Hammam Faroun, Hammam Musa and Ain Sukhna, respectively. The geothermal reserve results show that the geothermal potential of GOS can be used for low-scale energy production to partially fill the energy gap and meet the future requirements of Egypt.