Temperature Distribution Profile Research Articles

Effects of pulse parameters on the temperature distribution of a human head exposed to the electromagnetic pulse

The presence of blood–brain barrier (BBB) is a major obstacle to effectively deliver therapeutics to the central nervous system (CNS); hence, the outcomes following treatment of CNS diseases remain unsatisfactory. Fortunately, electromagnetic pulses (EMPs) provide a non-invasive method to locally open the BBB. To obtain the optimal pulse parameters of EMP-induced BBB opening to ensure the effective delivery of CNS drugs, it is particularly important to measure and assess the effects of pulse parameters on the temperature distribution in the human head exposed to EMPs. In this paper, the specific anthropomorphic mannequin phantom was adopted and the temperature increase in the human head induced by EMPs of different parameters was estimated in the software “COMSOL Multiphysics”. The results show that the temperature distribution profiles with different EMP parameters have almost similar characteristics, the highest temperature increase values in the human head are positively correlated with variations of EMP parameters, and potential hazards to the human head may occur when EMP parameters exceed the safety threshold, which will provide theoretical basis for seeking the optimal EMP parameters to open the BBB to the greatest extent within a safe range.

Experimental Investigation of Local Heat Transfer Measurement Having Inclined Discrete Ribs of Solar Air Heater Duct Using LCT Technique

Abstract The steady-state experiment using liquid crystal thermography has been conducted for the analysis of Nusselt number distribution over the absorber surface of solar air heater (SAH) duct having a gap with the staggered arrangement in inclined rib geometry to recuperate its thermal performance. The heat transfer experiment is performed with uniform heat flux and thermo-chromic liquid crystal (TLC) is utilized to show the temperature distribution profile over the ribbed surfaces of the rectangular duct of aspect ratio of 5. The colored pattern image of TLCs was acquired using a 3CCD (charged couple device) camera and exported to a Tagged Image File Format (TIFF) file format using frame grabbing SOFTWARE SAPERALT which was further processed to get hue, saturation, intensity (HSI) values. The flow parameters considered in this present investigation are Re, d/W, and g/e varied from 4000 − 12,500, 0.15 − 0.45, and 1 − 4, respectively. Experiments has been performed with fixed P/e, r/e, p′/P, α, and e/Dh of 10, 2, 0.6, 60 deg, and 0.0303, respectively. The influence of relative gap position and relative gap width on flow pattern has been analyzed. The maximum augmentation in Nu and f over the smooth duct was obtained as 4.01 and 4.28 times, respectively, at the optimum value of d/W = 0.35 and g/e = 2 under similar flow conditions. The maximum value of THPP obtained at d/W and g/e of 0.35 and 2, respectively, and Reynolds number of 12,445.

Ohmic heating effects and entropy generation for nanofluidic system of Ree-Eyring fluid: Intelligent computing paradigm

In present study, the nano-material flow of Ree-Eyring fluid model (NF-REFM) is examined by utilizing the technique of Levenberg Marquardt with backpropagated neural networks (TLM-BNNs). The flow is examined between two disks and the impacts of porosity and velocity slip are also analyzed. The partial differential equations (PDEs) representing the NF-REFM are transformed into system of ordinary differential equations (ODEs). Homotopy analysis method (HAM) is used to solve the ODEs and interpret the reference dataset for TLM-BNN. This dataset helps to compute the approximated solution of NF-REFM in MATLAB software. Regression analysis, Error histogram and MSE results, validates the performance of TLM-BNN. The flow effects on the velocity profile, temperature distribution and concentration profile are examined for different parameters. The results for entropy generation, Bejan number, Nusselt number, Sherwood number and skin friction coefficient are also discussed in this article.

Transient heat thermal load characteristics produced by a three-electrode capillary discharge generator

The behavior of the transient heat flux produced by a three-electrode capillary discharge generator working at a repetitive mode is presented in this paper. The radial distribution profiles of plasma temperature, electron density, and thermal load are obtained by the optical emission spectrometry and correction algorithm. Experiments with different capillary diameters and charging voltages are carried out, and the relation between the discharge characteristics and the geometry parameters of the capillary is measured. A maximum transient thermal load of 1.42 GW·m−2 is obtained with 10 Hz, which can meet the thermal load amplitude requirement of Type-I edge localized mode heat flux in the ITER-like Tokamak.

Analysis of heat fluxes in ceramic block type building pieces

In Norte de Santander, Colombia, there is a ceramic cluster made up of 59 companies dedicated to the production of construction materials derived from clay, a vernacular material with a wide extraction potential in the region. Fired clay products in different hollow block presentations represent 15% of industrial production, these construction pieces are low cost and show a high demand in the local masonry market, therefore, their thermo-physical characteristics largely build the thermal envelope of “Cucuteña”. This research comparatively evaluates the thermal behavior of four types of ceramic blocks with different perforations, applying the finite element method in thermal simulations that consider a conductivity of 0.407 W/m°C in the ceramic to establish the influence of the shape on the temperature distribution and heat flow profiles of each piece subjected to environmental conditions of a warm semi-arid climate, with average maximum temperatures of 33 °C and an average maximum solar radiation of 796.8 Wh/m2 under extreme climatic conditions in the city of San Jose de Cúcuta, Colombia. The results of the study allow identifying the ceramic block of 6 rectangular holes as the product that, due to its physical characteristics, presents a better alternative to be applied in constructions that seek thermal efficiency.

Numerical analysis of cellulose nanocrystals CNC for reducing cold damage to reproductive buds in fruit crops

Computational fluid dynamics (CFD) modeling of transient heat transfer was performed using ANSYS Fluent during the freezing process of buds treated with cellulose nanocrystal (CNC) to better understand the thermal behavior of CNC and the mechanism by which it provides cold damage protection. The numerical model developed were able to predict the temperature transition and the time required for the bud ice nucleation: the ice nucleation for the control bud started around 1080 s at about 270.2°K (−2.95 °C), while the ice nucleation for the CNC treated bud started around 1450 s at about 268°K (−5.15 °C). The CNC reduced the heat loss due to outgoing radiation to the external environment and decreased the heat flow loss due to convection heat transfer. As a result, CNC delays the formation of intracellular ice at low temperatures and protecting cold damage. The CFD simulation results of temperature distribution profiles were compared with the experimental data, yielding an average relative error of less than 15%. CFD model was able to estimate the convection heat flow, radiation heat transfer, and latent heat (phase change), all of which are difficult to investigate by making measurements in lab conditions.

Hybrid nanofluid flow containing single-wall and multi-wall CNTs induced by a slender stretchable sheet

The current research highlights the impact of thermal stratification on the magnetohydrodynamic flow of Fe3O4 hybrid carbon nanotubes (CNTs) scattered in the mixture of carrier-based fluid such as ethylene glycol and water (50–50%) over a slender stretching sheet. Single-walled and multi-walled carbon nanotubes were considered in the current study. The problem was initially constructed in the form of partial differential equations (PDEs) and then transformed to ordinary differential equations (ODEs) by using a suitable set of transformations. These transformed ODEs were solved using a built-in code accessible in MATLAB software called the boundary value problem of fourth-order (bvp4c). The emerging dimensionless constraints were achieved after utilizing the transformations and then later numerically computed. The outcomes indicated that the velocities and temperature augment due to the hybrid nanoparticles, while the velocities initially enhance and then decline in the case of decelerated flow (A≤0). However, the reverse impact was noted for the profiles of temperature distribution. The magnetic field reduces the velocities but augments the temperature distribution. Moreover, the thermal stratification elevates the temperature as well as the velocities.

Influence of temperature-salinity-depth structure of the upper-ocean on the frequency shift of Brillouin LiDAR.

Brillouin-based LiDAR is an alternative remote sensing technique for measuring the distribution profiles of temperature, salinity, and sound speed in the upper ocean mixed layer. Its principle is based on the dependence of Brillouin frequency shift on the temperature, salinity, and depth of ocean. Therefore, it is necessary to investigate the effect of various seawater parameters on Brillouin frequency shift for ocean remote sensing by using the Brillouin LiDAR. Here we theoretically and experimentally investigate the influence of temperature, salinity, and pressure (depth) of seawater on Brillouin frequency shift in the upper ocean for the first time. Numerical simulations of the distribution profiles of temperature, salinity, and Brillouin frequency shift in the upper-ocean mixed layers of East China Sea and South China Sea were performed, respectively, by employing the Brillouin equations and the World Ocean Atlas 2018 (WOA18). A special ocean simulation system was designed to carry out the stimulated Brillouin scattering (SBS) experiments for validating the numerical simulations. The results show that the seawater temperature is the most important factor for the Brillouin frequency shift in the upper-ocean mixed layer compared with the salinity and pressure. At the same salinity and pressure, the frequency shift increases by more than 10 MHz for every 1 °C increase in temperature. Also, the differences of Brillouin frequency shift between experimental and theoretical values at the same parameter conditions were analyzed. The experimental results coincide well with the theoretical simulations. This work is essential to future applications of Brillouin LiDAR in remote sensing of the temperature, salinity, or sound velocity profiles of ocean.

Simulation of catalytic upgrading in CAPRI, an add-on process to novel in-situ combustion, THAI

Based on the analysis of recent projections by the International Energy Agency (IEA), to meet the growing and subsequently declining demands of oil from now to 2040, we need up to around 770 billion barrels of oil. Since the worldwide total proved reserves of easy-and-cheaper-to-produce conventional oils is roughly only 520.2 billion barrels, the remaining 249.8 billion barrels must be obtained from unconventional petroleum resources (i.e. heavy oils and bitumen). These resources are however very difficult and costly to upgrade and produce due to their inherently high asphaltene contents which are reflected in their very high viscosities and large densities. However, still they should prove attractive development prospects if, as much as practicably possible, their upgrading can be performed in conjunction with in situ or downhole catalytic upgrading processes. Such projects will contribute significantly towards smoother and greener transition to full decarbonisation. Advanced technologies, such as the toe-to-heel air injection coupled to its add-on in situ catalytic process (i.e. THAI-CAPRI processes), have the potential to develop these reserves, but require further developmental understanding to realise their full capability. In this work, a new detailed procedure for numerically simulating the THAI-CAPRI processes is presented. The numerical model is made-up of Athabasca-type bitumen and it has a horizontal producer (HP) well that is surrounded by an annular layer of alumina-supported cobalt-oxide-molybdenum-oxide (CoMo/γ-Al2O3) catalyst. The simulation is performed using the computer modelling group (CMG) reservoir simulator, STARS. This new work has shown that the choice of the frequency factor of the catalytic reactions allowed model validation based on the degree of catalytic upgrading in form of API gravity. Overall, the work herein identifies the important parameters, such as API gravity, peak temperature, oil production rate, cumulative oil production, produced oxygen concentration, temperature distribution profile, extent of coke deposition on the catalyst surface, etc., governing the successful operation of the THAI-CAPRI processes. In particular, this study has shown that even in the vicinities of the mobile oil zone (MOZ) where the catalytic upgrading is expected to be taking place, the catalyst surfaces are covered with high concentration of coke. This finding is in parallel to the observations reported from experiment of CAPRI process alone. Therefore, it is concluded that when experimental studies of the THAI-CAPRI processes are to be conducted, a catalyst regeneration mechanism must be put in place in order to prolong the effectiveness and thus the life of the catalyst so that proper field operation design can be made. Additionally, the study has also shown that the temperature of the MOZ is less than 306 °C and that implies that an external source of heating the annular catalyst layer must be provided in order to effect the catalytic upgrading in the THAI-CAPRI processes. Thus, a new study should look at the feasibility of targeted heating (in the case of microwave) or conductive or resistive heating (in the case of electrical heating) to raise the temperature of the annular catalyst layer to that required to achieve the catalytic upgrading.

Field-scale experimental and numerical analysis of a downhole coaxial heat exchanger for geothermal energy production

The experimental and computational analyses of a 500 m deep coaxial borehole heat exchanger system for geothermal power generation are studied in this paper. The experiments are carried out on a high temperature resourced well with an average thermal gradient of 0.38 °C/m. The experiment lasts 456 h, and the findings are described in terms of fluid inlet and outlet temperatures, subsurface temperature distribution profiles over time, and flowrate. The in-situ ground temperature distribution profile is measured using Distributed Temperature Sensing System for different hours of the experiment. A detailed, three-dimensional, unsteady-state, finite volume-based computational model has been developed, which solves conjugate fluid-flow and heat transfer phenomena. The simulation outcomes are compared to the results of the experiments. With validated numerical model, to determine the circle of influence, temperature profile of the ground is observed at various radial distances from the borehole. A parametric study is performed by varying inlet temperature of the fluid, mass flow rate, and the thermal conductivity of the ground. The numerical model developed also predicts the temperature recovery behavior of the ground. The results indicate that the average output thermal power for 456 h from the geothermal system ranges from 172 kW to 262 kW based on operating condition chosen and the total thermal energy generated changes between 82 MWh and 194 MWh from a single borehole. After the extraction is terminated, around 86% of the initial ground temperature is restored after 456 h.

Experimental studies of the thermal regime of the room when using heating ceramic panels

The article presents the results of experimental studies of the parameters of ceramic panels. Experimental measurements of air temperature in a room for which an electric ceramic panel is used as heating devices are given. The automatic system of monitoring of temperature in the room is described.
 During the experiments it was determined that the surface temperature of the ceramic plate of the heater is higher in the center and decreases when approaching the edges. It is proved that the use of constant surface temperature is acceptable in CFD modeling of a room with ceramic electric heaters. The profile of temperature distribution on height of the room at its heating by means of an electric ceramic heater is resulted in work. The air temperature is relatively evenly distributed over the height of the room. In this study, when entering the quasi-stationary mode, the air temperature in the height of the room varied in the range from 24 to 27˚C, which is slightly higher than the norm for the temperature in domestic premises. In order to save energy in this case it is necessary to reduce the service life of ceramic electric heaters. In the future it is necessary to develop a thermophysical numerical model and verify it with the help of the obtained experimental data. In addition, with the help of the model you can conduct research and determine the optimal location of ceramic electric heaters in the space of the room. Key words: radiation ceramic heater, experimental research, temperature monitoring.

Stability Analysis of Unsteady MHD Rear Stagnation Point Flow of Hybrid Nanofluid

Previous studies have reported that investigating the stagnation point flow is relevant in a variety of industrial and technological processes, including extrusion and the polymer industries. Hence, the present work aims to analyse the heat transfer performance of unsteady magnetohydrodynamics (MHD) in hybrid nanofluid and heat generation/absorption impact. The multivariable differential equations with partial derivatives are converted into a specific type of ordinary differential equations by using valid similarity transformations. The resulting mathematical model is clarified utilising the bvp4c function. The results of various control parameters were analysed, and it was discovered that increasing the nanoparticle concentration and magnetic field increases the coefficient of skin friction along the stretching/shrinking surface. The inclusion of the heat generation parameter displays an upward trend in the temperature distribution profile, consequently degrading the heat transfer performance. The findings are confirmed to have more than one solution, and this invariably leads to a stability analysis, which confirms the first solution’s feasibility.

Thermal Performance Improvement and Contamination Control Strategies in an Operating Room

Operating room is a cleanroom that provides thermal comfort and good indoor air quality (IAQ) to support the surgery process. The heating, ventilation, and air conditioning (HVAC) system plays a critical role for the health protection regarding to IAQ, i.e., thermal performance, air changes per hour, pressurization, filtration, air distribution, etc. However, HVAC system in the operating room is operated for 24 hours year-round with intensive energy consumption. Energy-efficient approaches for the HVAC system is also quite challenging in term of contamination control to meet the standards specifications. In this study, a full-scale operating room was carried out through field measurements and numerical analysis extensively. Computational Fluid Dynamic (CFD) simulation has been carried out and verified with field measurement data. Thermal comfort performance along with temperature distribution and velocity profile have been simulated extensively. The energy-efficient approach by reducing the face velocity of the HEPA filter was examined which is done by reducing the velocity from 0.4, 0.3, 0.2 (m/s) for energy-saving concern but still need to meet the thermal performance and minimum contamination control requirement. The results reveal how the potential of HVAC systems to control air contamination, a comfortable thermal environment for occupants and the possibility of energy-efficient approaches in the operating room.

Temperature Profile of Hollow Aluminum Heated using Thermoelectric on Both Sides

The use of QCM sensors for gas sensors requires a reaction space known as headspace. Gas sensor headspace is needed to be heated to enable the gas molecule to react with the sensor sensitive layer. In the development of a sensor array, sensor placement requires space. As a result, the sensor experiences a temperature condition influenced by the sensor’s placement. Our headspace was made of a rectangular aluminum hollow. The hollow dimension was 40mm in height and 20mm in width with an aluminum thickness of 1mm. The aluminum hollow was heated on two sides using two thermoelectric TEC-12706. The temperature distribution of the aluminum heated by thermoelectric on both sides shows the temperature distribution profile, which depends on its position towards the thermoelectric. At the elevated temperature of 80°C, aluminum’s surface temperature shows a uniform temperature distribution in the direction perpendicular to the thermoelectric surface. In the direction parallel to the thermoelectric surface, the temperature profile shows a curved curve with the thermoelectric midpoint’s highest temperature. The temperature difference between the point parallel to the midpoint and the thermoelectric edge is 5°C. A temperature difference of less than 1°C is only obtained in an area 1cm wide from the thermoelectric midpoint position. This result suggests that a wider thermoelectric surface should be considered to obtain a wider area with uniform temperature.

Upgrading the performance of a six-cylinder CNG Engine with the induction of Turbocharger for HCV application

The world is having catastrophe of environmental pollution and fossil fuel depletion. Adaptation of alternative fuels is a healthy solution in reducing exhaust emissions in the automobile sector. Compressed Natural Gas (CNG) as a fleet fuel has played a vital role in the HCV sector. Many developmental and optimization work has been taken place for the CNG engines in the recent times. Due to the recent upsurge in diesel prices, the HCV sector is moving towards the CNG fuel vehicle. The HCV sector requires a heavy performance engine for its day-to-day application. In this research paper a baseline six-cylinder, naturally aspirated CNG engine used for bus application is selected to upgrade its power and torque performance. Based on the baseline CNG engine data, an appropriate turbocharger for the engine is selected with the help of M/s Garrett turbocharger manual. A 2-D simulation of the turbine is also carried out to understand the pressure and temperature distribution profile inside the turbine. The experimental results showing the increase in power, torque, volumetric efficiency, BMEP and thermal efficiency is illustrated in the research work below.

Computational Fluid Dynamics Applied to Study Coolant Loss Regimes in Very High Temperature Reactors

The nuclear energy is a good alternative to meet the continuous increase in world energy demand. In this pers-pective, VHTRs (Very High Temperature Reactors) are serious candidates for energy generation due to its inherently safe performance, low power density and high conversion efficiency. However, the viability of these reactors depends on an efficient safety system in the operation of nuclear plants. The HTR (High Temperature Reactor)-10 model, an experimental reactor of the pebble bed type, is used as a case study in this work to perform the thermohydraulic simulation. Due to the complex patterns flow that appear in the pebble bed reactor core CFD (Computational Fluid Dynamics) techniques are used to simulate these reactors. A realistic approach is adopted to simulate the central annular column of the reactor core. As geometrical model of the fuel elements was selected the BCC (Body Centered Cubic) arrangement. Parameters considered for reactor design are available in the technical report of benchmark issues by IAEA (TECDOC-1694). We obtain the temperature profile distribution in the core for regimes where the coolant flow rate is smaller than recommended in a normal operation. In general, the temperature distributions calculated are consistent with phenomenological behavior. Even without considering the reactivity changes to reduce the reactor power or other safety mechanisms, the maximum temperatures do not exceed the recommended limits for TRISO fuel elements.

A computational technique for thermal analysis in coaxial cylinder of one-dimensional flow of fractional Oldroyd-B nanofluid

It is a focused fact in thermal analysis that if a particular alloy changes from liquid to solid from higher temperature to lower temperature, then reactions between fluid particles occur at equal rates of heat transfer. In this manuscript, mathematical synchronisation in coaxial cylinders of one-dimensional flow of fractional Oldroyd-B nanofluid is developed for heat transfer in the absence of pressure gradient. The modern fractional approach-based non-singular and local kernel is particularised on the boundary layered cylindrical governing equations for temperature distribution and velocity profile. To get rid of the complexity of computation from governing equations based on cylindrical domain, the powerful techniques of integral transforms are employed. Moreover, the fractionalised Oldroyd-B nanofluid, containing a mixture of small nanoparticles, namely, (molybdenum disuphide), (copper), (aluminium oxide), (silver) with ethylene glycol as a base fluid, is also discussed for velocity profile and temperature distribution. In the light of thermal relaxation time and Prandtl number, our results suggest that smaller values of thermal relaxation time generate oscillation between temperature distribution and Prandtl number produced thermal fluctuations with an intrinsic structure.

Thermal analysis of a moving fin using the radial basis function approximation

AbstractIn this study, the heat transfer and temperature distribution in a moving fin have been analyzed. The fin velocity was considered constant, and the thermal conductivity coefficient was variable with temperature, and the fin was under the effect of convection, radiation, and conduction heat transfer. The main equation of the problem was solved by the radial basis function method and validated by the numerical 4th‐order Runge–Kutta method. Several parameters such as thermal conductivity parameter from 0 to 1, sink temperature parameter from 0.2 to 0.8, and Nr, Nc, Pe number from 1 to 4, were examined. The outcomes illustrate that increasing the thermal conductivity by 51.5% raises the conduction heat transfers as well as the dimensionless temperature by 3.42%. Moreover, increasing the sink temperature leads to a slow rise in ambient temperature by 22.8% in the maximum state. By raising the Nc and Nr parameters, near 33.3%, the temperature distribution profile is declined by 4% and 10.5%, respectively. And increasing the Pe number by 100% results in a rise in the temperature distribution by about 7%.

Numerical performance of thermal conductivity in Bioconvection flow of cross nanofluid containing swimming microorganisms over a cylinder with melting phenomenon

This study investigates the effects of melting phenomena and non-linear thermal radiation in Cross nanofluid bioconvection flow with motile microorganisms with a convective boundary over a cylinder. Brownian motion and thermophoresis diffusion are also taken into account in this mathematical model. A governing partial differential equation is used to represent the given flow phenomena. The proper dimensionless transformation is then employed to convert the PDE controlling system into an ordinary one. Bvp4c numerically solves redesigned ODE problems using a shooting strategy in the computational tool MATLAB. Figures versus velocity, temperature distribution, nanoparticle concentration, and microbe concentration profiles are used to analyze and expound on the notably involved aspects thoroughly. It has been demonstrated that increasing the estimates of a mixed convection parameter can enhance velocity. By increasing the Prandtl number, the temperature and concentration of nanoparticles decrease. A high Peclet value lowers the microorganism's profile.

Influence of Chemical Reaction and Arrhenius Activation Energy on Hydromagnetic Non-Darcian Casson Nanofluid Flow with Second-Order Slip Condition

This article investigates the combined effect of second-order velocity slip, Arrhenius activation energy and binary chemical reaction on reactive Casson nanofluid flow in a non-Darcian porous medium. The governing equations of the problem were first non-dimensionalized and later reduced to ordinary nonlinear differential equations by adopting a similarity transformation. The emerging nonlinear boundary value problem was solved by using Galerkin weighted residual method (GWRM). The obtained results were compared with those found in the literature to validate our method. The impact of pertinent parameters on the velocity component, temperature distribution and concentration profile are presented using graphs and were discussed. The computational results show that an increase in second order slip parameter significantly results to an increase in the temperature as well as nanoparticle concentration profiles, while it reduces the velocity profile.