Heat Absorption Effects Research Articles

Exergy performance of a reversed circular flow jet impingement bifacial photovoltaic thermal (PVT) solar collector

The primary limitation of photovoltaic thermal (PVT) technologies is the adverse effect of solar irradiance-induced heat absorption. In order to enhance the efficiency of the system, it is essential to incorporate a cooling mechanism. The utilization of a reversed circular flow jet impingement (RCFJI) was implemented as a cooling mechanism for a bifacial PVT solar collector. This study aims to analyze the exergy efficiency of a RCFJI bifacial PVT solar collector. An indoor experiment was conducted using a solar simulator with a solar irradiance of 500–900W/m2 and a mass flow rate of 0.01–0.14 kg/s. The findings revealed that the highest photovoltaic exergy attained was 47.2W under solar irradiance of 900W/m2 and a mass flow rate of 0.14 kg/s. Meanwhile, the highest thermal exergy attained was 9.67W under 900W/m2 solar irradiance and 0.14 kg/s mass flow rate. Overall, the exergy efficiency attained a maximum value of 12.64% under 900W/m2, while the lowest exergy efficiency observed was 12.25% under 500W/m2. In addition, the optimal operational mass flow determined was 0.06 kg/s. The findings indicate that the optimal performance of the RCFJI bifacial PVT solar collector is achieved through higher exergy efficiency, which signifies a reduced requirement for input energy. Consequently, more energy can be harnessed.

Magnetohydrodynamics free convection couette flow and heat transfer through a vertical porous plate with heat generation and absorption effect

This research examines the impact of suction/injection and permeability of porous materials on a steady natural convection Couette flow of a viscous incompressible fluid passing through a vertical porous plate. The dimensionless governing momentum and energy equations were solved exactly. Graphs were plotted to check the impact of the governing flow parameters and a table was plotted for comparison of the results. It was found from the investigation that, the fluid injection (λ>0) increases the fluid velocity and temperature distributions while the magnetic field (M) retards the fluid velocity. It is also noteworthy to mention that the suction (λ>0) reduces the fluid velocity and temperature distributions in the channel. The velocity profile is observed to increase with increase in the permeability (K) of the materials.

Heat transfer analysis of water-ethylene glycol (50:50) based nanofluid over a cone with the influences of magnetic field and uniform heat generation/absorption

Aim:The novelty of the problem is to examine the heat transfer analysis of H2O–C2H6O2 (50:50) mixture based Al2O3 and Fe3O4 over a heated and spinning down-pointing vertical cone with the effect of heat generation or absorption in the presence of magnetic field. Findings:Results are demonstrated in terms of graphs to examine the influence of various physical parameters that come across such as Magnetic parameter M, Spin parameter ϵ, Nanoparticle volume fraction ϕ, Heat generation or absorption parameter Δ, velocity slip parameter Γ1 and thermal slip parameter Γ2 on dimensionless velocity profile F′(y), G(y) and temperature profile H(y). The effect of M, ϵ, ϕ, Δ,Γ1,Γ2on skin friction and local Nusselt number are examined in tabulation form. Significant outcomes:It is pointed out that enhancement in Magnetic parameter and thermal slip parameter leads to declination of the velocity profile. Influence of Heat generation or absorption parameter magnifies the thermal characteristic of the flow. Moreover, the numerical statistics was triggered and catalogued to analogize the results of existing outcomes with those of previous literature for some special cases and established excellent agreement. Fe3O4 possess 0.78% and 0.92% of high surface drag force and heat transfer rate respectively than Al2O3 with respect to heat generation or absorption parameter. Approach:The system of partial differential equations is transformed into set of nonlinear ordinary differential equations. Solutions for the system of nonlinear Ordinary differential equation are obtained by Numerical method. The numerical scheme is developed based on fourth order Runge Kutta scheme along with shooting techniques. Practical implications:In this current growing scenario, engineers and scientists are making an endeavour to gratify the global needs. Nanofluids are considered as inevitable one for achieving industrial and global needs. The investigation of heat transfer over rotating cone with the effect of magnetic field is of considerable interest due to its presence in industrial and technological applications. Especially in the design of turbines and turbo equipment’s and in understanding the path of flight of rotating wheels.

Entropy analysis of unsteady MHD nanofluid flow over a stretching surface with effects of variable viscosity and nonuniform heat generation

An unsteady two-dimensional nanofluid flow across a permeable stretched sheet is examined in terms of thermodynamic analysis. Water is utilized as the basic fluid, together with four distinct types of nanoparticles: copper (Cu), copper oxide (CuO), aluminum oxide (Al2O3), and titanium dioxide (TiO2). An external source is used to describe the heat transfer phenomena. The effects of heat generation and absorption are also taken into account. The nonlinear partial differential equations are transformed into a system of nonlinear ordinary differential equations via a similarity transformation. The spectral quasi-linearization approach is then used to numerically integrate the altered equations. Except when otherwise noted, the findings are provided for copper nanoparticle situations. A visual and detailed explanation of the effects of several physical factors on the profiles of dimensionless velocity, temperature, average entropy generation function, skin friction, and the Nusselt number are discussed. As exceptional circumstances of the current findings, there is a strong agreement between the current conclusion and the findings of the other researchers. The average entropy generation number, temperature, and velocity profiles are shown to be strongly influenced by regulating factors. It is concluded that the average entropy generation decreased in the presence of a temperature- and space-dependent heat source/sink, but it improves with enhanced viscosity parameter. The significance of the present study has frequent applications in the major area of heat transfer enhancement in renewable energy systems, industrial thermal management, and also materials processing.

Convective heat and mass transfer rate on 3D Williamson nanofluid flow via linear stretching sheet with thermal radiation and heat absorption

A mathematical analysis is communicated to the thermal radiation and heat absorption effects on 3D MHD Williamson nanoliquid (NFs) motion via stretching sheet. The convective heat and mass boundary conditions are taken in sheet when liquid is motion. As a novelty, the effects of thermal radiation, heat absorption and heat and mass convection are incorporated. The aim is to develop heat transfer. Williamson NFs are most important source of heat absorption, it having many significant applications in “energy generation, HT, aircraft, missiles, electronic cooling systems, gas turbines” etc. The suitable similarity transformations have been utilized for reduce basic governing P.D. E’s into coupled nonlinear system of O.D. E’s. Obtained O.D. Es are calculated by help of R–K–F (“Runge–Kutta–Fehlberg”)4th order procedure with shooting technique in MATLAB programming. We noticed that, the skin friction coefficient is more effective in Williamson liquid motion when compared with NFs motion with higher numerical values of stretching ratio parameter, Williamson liquid motion is high when compared to NFs motion for large values of magnetic field. We compared with present results into previous results for various conditions. Finally, in the present result is good invention of previous results.

MHD Free convection flows of Jeffrey fluid with Prabhakar-like fractional model subject to generalized thermal transport

This article examines the effects of magnetohydrodynamics and heat absorption on an incompressible Jeffrey fluid’ time-dependent free convection flow over an infinite, vertically heated plate with homogeneous heat flux. The constitutive equation for heat flow utilizes the Prabhakar-like fractional derivative. The Laplace transform technique obtains the precise solution for the momentum and thermal profiles. The typical case and well-known outcomes from the literature are retrieved as restraining cases. The graphical analysis of the impact of the flow and fractionalized parameters on the thermal and momentum profiles is presented. Additionally, a comparison is made between the ordinary model and the Prabhakar-like fractional model, which shows that the latter better captures the retention of the physical features of the problem. It is concluded that the Prabhakar-like fractional model is better suited for describing the memory effect of the thermal and momentum fields.

Computational Simulation of Unsteady Squeezing Hybrid Nanofluid Flow Through a Horizontal Channel Comprised of Metallic Nanoparticles

The characteristics of hybrid nanofluid flow contained copper (Cu) and cobalt ferrite (CoFe2O4) nanoparticles (NPs) across a squeezing plate have been computationally evaluated in the present report. In biomedical fields, in very rare cases fluid flow through a static channel. Similarly in industrial sights, we are also often observed that the fluid flows through comprising plates rather than fixed plates (flow in vehicle’s engine between nozzles and piston). CoFe2O4 and Cu nanoparticles are receiving huge attention in medical and technical research due to their broad range of applications. For this purpose, the phenomena have been expressed in the form of the system of PDEs with the additional effect of suction/injection, heat source, chemical reaction, and magnetic field. The system of PDEs is simplified to the dimensionless set of ODEs through similarity replacements. Which further deals with the computational approach parametric continuation method. For the validity and accuracy of the outcomes, the results are confirmed with the existing works. The results are displayed and evaluated through Figures. It is detected that the hybrid nanoliquid has a greater ability for the velocity and energy conveyance rate as related to the nanofluid. Furthermore, the energy profile declines with the consequences of unsteady squeezing term, while enhances with the effects of suction factor, heat absorption and generation, and lower plate stretching sheet.

Unsteady thin film flow with ohmic heating and chemical reactions

In this study, we have analyzed magnetohydrodynamic (MHD) consequences on the heat and mass transmission within unsteady dissipated liquid film flow. Flow is generated due to stretchable surface accompanied with effects of ohmic heating, chemical reaction and heat absorption. Moreover, the flow governing partial differential equations (PDEs) are further modified into equivalent ordinary differential equations (ODEs) by applying regular perturbation method to get its analytical solution after that we have applied sixth-order Runge–Kutta technique to get its numerical solution. These two solutions are validating each other in the simulations. Figures are plotted to study the changes in physical quantities like skin friction coefficient, concentration, velocity, temperature, Sherwood and Nusselt number with the variations of Prandtl numbers Pr, parameters of chemical reaction [Formula: see text], Eckert numbers Ec, magnetic parameter Ha (also known as Hartman number) Schmidt number and coefficient of heat absorption [Formula: see text].

Coupling effect on the thermal hazard assessment of hazardous chemical materials via calorimetric technologies and simulation approaches

The coupling effect of heat absorption and release exists in the thermal decomposition of a few chemical materials. However, the impact of the above coupling on thermal hazard assessment is not considered in the literature studies. In this work, nitroguanidine (NQ) and 1,3,5-trinitro-1,3,5-triazine (RDX) are selected as representative materials to explore the influence of the coupling effect on the thermal hazard assessment of chemical materials. The linear heating experiments of NQ and RDX are carried out by a microcalorimeter and synchronous thermal analyser. The thermal decomposition curves are decoupled by advanced thermokinetics software. The thermal decomposition and kinetic parameters before and after decoupling are calculated. The results of TG experiment show that both NQ and RDX began to lose mass during the endothermic stage. The endothermic melting and exothermic decomposition of NQ and RDX are coupled within this stage. The coupling effect has different degrees of influence on its initial decomposition temperature and safety parameters. Compared with the parameters in the coupling state, the initial decomposition temperature and adiabatic induction period after decoupling decrease. The self-accelerating decomposition temperature increases, and internal thermal runaway time decreases. In the thermal hazard assessment of chemical materials with coupling effects, the calculated parameters after decoupling should be taken as an important safety index.

Effect of combination of explosion venting and chemical barrier on starch explosion suppression in a large scale connected vessels

The explosion of starch poses a potential threat to the process safety of food and energy enterprises in product processing and storage. To control explosion, a 5 m3 columnar tank with a 10 m long connecting pipe at one end and a 700 mm diameter explosion vent at the other end was built as an experimental device. Combined controlled explosion experiments were conducted using a rupture disc with a static activation pressure of 10 kPa and a chemical barrier containing ABC powder with nitrogen as the driving gas to investigate the pressure and flame change characteristics inside the vessel and piping. The experimental results show that the maximum explosion pressure in the connected vessel without explosion venting is 41.21kPa and the maximum pressure rise rate is 5.20 bar/s. Explosion venting reduces the maximum explosion pressure and pressure rise rate in the vessel by 52.31 % and 21.92 %, respectively, and reduces the flame propagation speed in the pipeline, so that the chemical barrier device can effectively isolate the flame when the installation distance is more than 6 m. The N2 and ABC dry powder two-phase explosion suppressant produced an effective inhibition effect through the physical effects of oxygen insulation, heat absorption, and thermal transmission weakening, as well as the chemical effect of eliminating explosive radicals. The explosion venting provides an initial defense by releasing any remaining pressure and heat of the explosion, while the chemical barrier provides a secondary layer of protection by extinguishing the flame and suppressing the explosion in the pipe to prevent further damage. This combination can greatly reduce the risk of equipment damage, injuries, and fatalities caused by explosions in industrial settings.

Heat and mass transfer on unsteady MHD convective flow through porous medium between two vertical plates with chemical reaction

The present investigation explores the unsteady magnetohydrodynamic (MHD) free convective oscillating flow of an optically thin incompressible viscous fluid embedded in two parallel porous walls under the influence of an externally applied transverse magnetic field with a chemical reaction. The radiative heat flux and heat absorption effects are taken into account. The governing equations are solved for the velocity, temperature, and concentration distributions making by making use of the Laplace transformation methodology. The impacts of a combined of relevant flow parameters on concentration, temperature, and velocity distribution are discussed with pertinent non-dimensional parameters. Also, the friction factor coefficient, Nusselt number, and Sherwood number are found and explored in tabular format. The magnitude of the velocity field is climbing with an increase in permeability parameters, and thermal and solutal buoyancy forces. Heat absorptions coefficient and Prandtl number are increasing, which reduces the temperature. Also, the skin friction coefficient strengthens with mounting in the Hartmann number.

Chemical reaction effects on mhd heat and mass transfer of a Jeffrey fluid flow with viscous dissipation and joule heating through a porous stretching sheet

The effect of chemical reaction on heat and mass transfer of a Jeffrey fluid flow with viscous dissipation and joule heating over a porous stretching sheet in the presence of an external magnetic field and internal heat generation or absorption effects are examined. By applying similarity variables, the governing non-linear partial differential equations are converted into nonlinear ordinary differential equations. MATLAB BVP4c approach gets numerical solutions to these equations. The things of several constraints on velocity, temperature, and concentration flow are studied and shown graphically. Moreover, the consequence of system parameters on friction factor, Nusselt, and Sherwood numbers are also investigated and arranged for different values of Jeffrey parameter, reaction rate parameter, magnetic field, Prandtl number, suction parameter, porosity parameter, radiation parameter, internal heat generation or absorption, Eckert number and Schmidt number in tabular form. The findings of this study are very well-acknowledged with current research.

木造住宅における潜熱蓄熱建材の導入効果に関する研究（その3）：室内付属物を考慮した潜熱蓄熱建材の敷設方法の効果比較

The potential of using Phase Change Material (PCM) in wooden house has been investigated. Since the cost of the PCM is high, searching for a laying position with high heat absorption and dissipation efficiency has been shown as a problem to solve. At the same time, the internal screen also causes changes in the room surface temperature, which in turn affects the heat absorption effect of PCM. In this study, we focused on how the internal screen affects the thermal storage effect of PCM and discuss the means to improve the thermal storage effect.

Thermal switching ratio of semiconducting polymers with spatially graded doping

The switching ratio of a thermal switch is a key design parameter, and electrically activated switches based on thermoelectric effects have been reported to produce large switching ratios over a wide range of temperatures. Previous switches based on the Seebeck effect have switching ratios that are limited by the thermoelectric figure-of-merit zT. Perhaps, more importantly, they are limited by their device construction of alternating p-type and n-type materials with soldered junctions. Alternatively, we show that semiconducting polymers with spatially graded doping can offer similar switching ratios due to a volumetric heat absorption effect. This occurs in heavily doped polymers, which exhibit a sharp decrease in the Seebeck coefficient as charge carriers become fully delocalized. Such heat absorption is analogous to the Thomson effect, where heat is locally absorbed due to temperature-dependent variation of the Seebeck coefficient. Here, a theoretical model is derived to solve the 1D heat equation with spatially graded doping, allowing for optimization of the doping profile for a given material system. Four different material systems are compared according to an analysis of reported measurements to determine the upper limit of the switching ratio. A hypothetical Thomson switch based on poly(3,4-ethylenedioxythiophene) doped with ferric tosylate can produce switching ratios up to 12 under a thermal bias of 10 K, a threefold increase compared to a Peltier switch of the same material. Like a Peltier switch, the switching ratio of a Thomson switch diverges under a small thermal bias. Under a large thermal bias, the switching ratio converges toward that of an equivalent Peltier switch.

Inerting effect of CaCO3 powder on flame spread of wood dust layer

The effect of CaCO3 powder, a typical inert dust, on the flame spread characteristics of wood dust layers was studied using an experimental device to understand the ignition characteristics of and develop inert explosion-proof technology for deposited wood dust. The results showed that the flame spread velocity (FSV) of the mixed dust layer was affected by the dispersion effect of CaCO3 powder and physical heat absorption. As the CaCO3 powder mass fraction increased, the FSV of the dust layer first increased and then decreased, reaching a peak at a 50% mass fraction. Moreover, the front-end temperature of the flame gradually decreased, and the red spark faded. The combustion reaction of the mixed dust layer could be more completed, and the colour of the combustion residue changed from charcoal black to charcoal grey. The coupling effect of the initial temperature and wind speed can promote an increase in the FSV in the mixed dust layer. The Gauss–Amp model of the FSV of the wood dust layer and mass fraction of CaCO3 powder showed that the peak of the FSV occurred when the mass fraction of CaCO3 powder was between 40 and 50%. Thus, a good inerting and explosion-proof effect can be achieved by using CaCO3 powder with a mass fraction of more than 50%; it can improve the whole inerting process. Inert explosion-proof technology should be considered when assessing fire and explosion risk of dust in real process industry situations.

Thermodynamic irreversibility analysis of water conveying argentum and titania nanoparticles subject to inclined stretching surface

Hybrid nanofluids deliberately improve the characteristics of heat transmission and pressure drop in comparison to conventional nanofluids. The current study aims to inspect the energy transport and thermodynamic irreversibility effects of the buoyancy induced hybrid nanofluid flow. The mixture contains titania and argentum/silver nanoparticles over a vertically inclined stretching surface. The effects of heat generation and absorption, buoyancy and Lorentz force are added as well. The fact that nanoparticles have higher thermal and electrical conductivities means that this study can also be used for applications involving energy storage and catalytic supports. The problem is solved via bvp4c, a built-in technique in MATLAB. The similarity ansatzes are used to develop a system of ordinary differential equations. A comparison of current results with the existing ones in literature are also found to be in exact agreement. The asymptotic behavior for low and high magnetic number is determined. The nanoparticles concentration enhanced the flow field and temperature distribution; however, it reduced the entropy generation phenomenon and pressure field, causing pressure drop. The numerical and asymptotic values (for low magnetic number) of heat transfer rate and coefficients of skin frictions of free convective flow are declined due to increment in Prandtl number.

Ablation Mechanism of AlSiB-C/C Composites under an Oxy-Acetylene Torch

In order to improve the ablation resistance of C/C composites, an AlSiB alloy (mass ratio of Al/Si/B = 2:4:1) was used as a dissipative agent to fill the pores of a C/C composites matrix by reactive melt infiltration to prepare AlSiB-C/C composites. The microstructure evolution and ablation behavior of the obtained AlSiB-C/C composites (mass ratio of Al/Si/B = 2:4:1) under oxy-acetylene flame were investigated by SEM after ablating for 25 s, 50 s, 100 s and 150 s. At the beginning of the ablation process, thermal chemical erosion played a leading part. By using the heat-absorption effect of sweating and the sealing protection effect of the oxide layer, AlSiB-C/C composites significantly reduced the ablation surface temperature, and the linear ablation rate was 4.04 μm/s. With the process of ablation, thermal mechanical erosion tended to dominate. The specimen surface could not form a continuous covering of oxide film to slow down the flame scour, resulting in non-uniform ablation and further expansion of the ablation pit. The self-transpiration cooling behavior and the self-sealing of the ablation products of the dissipative agent played an important role in reducing the extent of thermal chemical erosion and preventing matrix ablation.

Heat and mass transfer through MHD Darcy Forchheimer Casson hybrid nanofluid flow across an exponential stretching sheet

AbstractRecent research has reported on the energy and mass transition caused by Casson hybrid nanofluid flow across an extended stretching sheet. Thermal and velocity slip conditions, heat absorption, viscous dissipation, thermal radiation, the Darcy effect, and thermophoresis diffusion have all been considered in the study of fluid flow. Fluid flow is subjected to an angled magnetic field to control the flow stream. Cu and Al2O3 NPs are dispensed into the Casson fluid to create a hybrid nanofluid (blood). The suggested model of flow dynamics is an evolving nonlinear system of PDEs, which is then reduced to a system of dimensionless ODEs using similarity proxies. The resulting set of ODEs is solved using the analytical program “HAM” for further processing. However, it has been found that the effects of the suction parameter and Darcy Forchhemier considerably reduced the energy transference rate of hybrid nanoliquids. It has been discovered that the effects of thermal radiation and heat absorption increase the energy transfer rate. Furthermore, the velocity and energy transmission rate are noticeably amplified by the dispersion of copper and cobalt ferrite nanoparticles in the base fluid.

Hybrid nanofluid mixed convection in a cavity under the impact of the magnetic field by lattice Boltzmann method: Effects of barrier temperature on heat transfer and entropy

The aim of this study is to investigate the effect of barrier temperature on hybrid nanofluid MHD mixed convection via LBM. The shape of the evaluated chamber is trapezoidal, subjected to heat absorption or heat generation. Reducing the share of heat transfer in entropy production up to about 14% is possible by changing the blocking temperature from 1 to zero. By increasing the effect of buoyancy forces, a stronger convection current is formed inside the chamber. When the magnetic field is applied, it reduces the fluid flow speed and temperature gradient. This factor leads to the reduction of convection effects and the weakening of buoyancy forces. So, the stronger the convection, the more obvious this effect. The flow under the influence of heat production results in the lowest mean Nusselt value. The higher heat absorption or heat generation coefficients, lead to a more effective magnetic field application. If the number of Richardson is low, heat absorption or heat generation effects are more obvious. Bejan Number, for the coefficient of heat absorption or heat generation, equals +5 (Q=+5), which is about 10% & 18% higher than Q=0 and Q=-5, respectively.

Multi-signal information increment sensing system for point-of-care testing of NADH based on cobalt oxyhydroxide nanoflakes

Herein, an innovative multi-signal information increment sensor was proposed to achieve sensitive and immediate detection of NADH (POCT) by measuring a series of values such as pressure, temperature and weight without the need for complex instrumentation. Hydrogen peroxide (H 2 O 2 ) can be decomposed to O 2 by cobalt hydroxide (CoOOH) nanosheets in a sealed bottle, accompanied by a significant pressure and a significant temperature increase due to the exothermic effect of the reaction (ΔH = -98.2 kJ/mol). The increase in pressure forces a certain amount of H 2 O to spill out from the drainage bottle into the water collection bottle pre-filled with ammonium chloride (NH 4 Cl), resulting in a significant decrease in the bottle temperature due to the good heat absorption effect of NH 4 Cl (ΔH=14.8 kJ/mol). In contrast, NADH can significantly inhibit the catalytic activity of CoOOH and a significant decrease in the pressure, overflow water weight, and temperature response was observed. The changes in response signal can be easily obtained by barometer, electronic balance and thermometer. Importantly, signal amplification is achieved by coupled superposition of incremental and decremental temperature signals to improve the sensitivity of the platform. The obtained barometric pressure difference, temperature difference, weight change and NADH concentration showed good linearity. With a linearity range of 0.9-19 mg mL –1 and a sensor detection limit of 0.26 mg mL –1 NADH, the quantification results of this multi-signal sensor were consistent with those of High-Performance Liquid Chromatography (HPLC).