A symplectic approach for the fractional heat transfer and thermal damage in 2D biological tissuesXu, Chenghui; Leng, Sen; Li, Deen; Yu, Yajun
2023 International Journal of Numerical Methods for Heat and Fluid Flow
doi: 10.1108/hff-01-2023-0013
This paper aims to focus on the accurate analysis of the fractional heat transfer in a two-dimensional (2D) rectangular monolayer tissue with three different kinds of lateral boundary conditions and the quantitative evaluation of the degree of thermal damage and burn depth.Design/methodology/approachA symplectic method is used to analytically solve the fractional heat transfer dual equation in the frequency domain (s-domain). Explicit expressions of the dual vector can be constructed by superposing the symplectic eigensolutions. The solution procedure is rigorously rational without any trial functions. And the accurate predictions of temperature and heat flux in the time domain (t-domain) are derived through numerical inverse Laplace transform.FindingsComparison study shows that the maximum relative error is less than 0.16%, which verifies the accuracy and effectiveness of the proposed method. The results indicate that the model and heat source parameters have a significant effect on temperature and thermal damage. The pulse duration (Δt) of the laser heat source can effectively control the time to reach the peak temperature and the peak slope of the thermal damage curve. The burn depth is closely correlated with exposure temperature and duration. And there exists the delayed effect of fractional order on burn depth.Originality/valueA symplectic approach is presented for the thermal analysis of 2D fractional heat transfer. A unified time-fractional heat transfer model is proposed to describe the anomalous thermal behavior of biological tissue. New findings might provide guidance for temperature prediction and thermal damage assessment of biological tissues during hyperthermia.
Heat transfer enhancement in a corrugated chamber filled with hybrid nanofluid under an influence of internal heated plateHamza, Naseer H.; Theeb, Maathe A.; Sheremet, Mikhail A.
2023 International Journal of Numerical Methods for Heat and Fluid Flow
doi: 10.1108/hff-03-2023-0113
The purpose of this research is to scrutinize numerically the effect of internally equipped nonuniformly heated plate within wavy cavity on heat transfer enhancement in the case of hybrid nanofluid flow.Design/methodology/approachThe two-dimensional, steady, laminar, Newtonian and incompressible thermo-fluid flow phenomenon has been investigated numerically using Galerkin method. The considered parameters including number of waves (3–7), nondimensional length of heated plate (0.4–0.8), plate inclination angle (0º–90º), Rayleigh number (103–106) and concentration of nanoparticles (0.0–2.0) have been investigated in combination with involving hybrid nanofluid as a working fluid to augment thermal properties effectively. Two vertical wavy boundaries have low temperature whilst the other horizontal surfaces are adiabatic.FindingsThe Rayleigh number has a moderate impact on the values of Nusselt number, and skin friction parameter varied from 103 to 105 while it strongly affects them for Ra = 106, where Nu is roughly doubled (approximately 200%) in comparison with its value at Ra = 105 for all cases. Stream function is changed by the orientation of heated plate and Ra values, where its maximum value was 12.9 in horizontal position and 13.6 at vertical one. Results indicate a separation from the wavy walls at low Ra which tends to keep stagnation region at the deep parts of corrugated walls contrary the case at high Ra. The behavior of the isotherm contours tends to be distributed more evenly at lower values of Ra and angle of inclination lower than 45º. The resulting properties from mixing two materials for hybrid nanofluid into one base fluid show a good compromise between thermal capacity and heat conductivity, which is improved by 16% that leads to enhanced convective energy transport in the wavy chamber.Originality/valueThe originality of this work is the considered physical phenomenon where an influence of internal nonuniformly heated plate has been studied for the irregular geometry filled with a hybrid nanofluid. Such analysis allows defining the possible heat transfer enhancement for such an irregular cavity and inner heated plate.
Numerical and experimental studies of thermal performance enhancement for parabolic trough solar collector using none-circulated CuO/synthetic oil nanofluidElmnefi, Mohamed; Al-Khazraji, Waqas
2023 International Journal of Numerical Methods for Heat and Fluid Flow
doi: 10.1108/hff-11-2022-0659
One of the existing and commonly used solar energy harvesting devices is the parabolic trough solar collector (PTSC). Because of their ability to operate in low and medium temperatures, parabolic trough concentrators are widely used in power generation plants and industrial process heating applications. Therefore, the investigation of how different operating conditions affect these devices’ overall efficiency has received a great deal of attention in the recent decade. This study aims to enhance the thermal performance of the PTSC and reduce the system cost.Design/methodology/approachIn the novel configuration, a noncirculated nanofluid absorbs solar radiation through a glass wall. The base fluid was synthetic oil (5W30), and the nanoparticles used were copper oxide. The heat captured is immediately absorbed by the water circulating inside the copper tube immersed in the nanofluid. ANSYS FLUENT 15.0 was used for carrying out computational fluid dynamics simulations for two models of single and triple copper tubes. The experimental results obtained from a test rig constructed for this purpose were compared with the numerical outcomes of the single copper tube model.FindingsThe findings of the simulation demonstrated that performance was superior for the single copper tube model over the triple copper tube model. The numerical findings of the single copper tube model were compared with the experimental results. The numerical and experimental results differed from 3.17% to 5.6%. Investigations were carried out to study the effects of varying the volumetric flow rate of (20, 40, 60 and 80 L/h) and water inlet temperatures of (300, 315 and 330 K) on the effectiveness and performance of the newly developed model. Additionally, two nanofluid volume fractions of 0.05% and 0.075% were used for investigating their effect on the performance of the novel configuration. According to the findings, the highest thermal efficiency of 55.31% was recorded at 0.075% concentration and 80 L/h volume flow rate.Originality/valueIn this study, a novel direct absorption solar collector configuration using a noncirculated nanofluid was designed to enhance the thermal efficiency of PTSC. This new approach makes it possible to boost the thermal performance of the PTSC and lower the system’s cost.
Hybridized nanofluidic convection in umbrella-shaped porous thermal systems with identical heating and cooling surfacesBiswas, Nirmalendu; Mandal, Dipak Kumar; Manna, Nirmal K.; Gorla, Rama S.R.; Chamkha, Ali J.
2023 International Journal of Numerical Methods for Heat and Fluid Flow
doi: 10.1108/hff-11-2022-0639
This study aims to investigate the impact of different heater geometries (flat, rectangular, semi-elliptical and triangular) on hybrid nanofluidic (Cu–Al2O3–H2O) convection in novel umbrella-shaped porous thermal systems. The system is top-cooled, and the identical heater surfaces are provided centrally at the bottom to identify the most enhanced configuration.Design/methodology/approachThe thermal-fluid flow analysis is performed using a finite volume-based indigenous code, solving the nonlinear coupled transport equations with the Darcy number (10–5 ≤ Da ≤ 10–1), modified Rayleigh number (10 ≤ Ram ≤ 104) and Hartmann number (0 ≤ Ha ≤ 70) as the dimensionless operating parameters. The semi-implicit method for pressure linked equations algorithm is used to solve the discretized transport equations over staggered nonuniform meshes.FindingsThe study demonstrates that altering the heater surface geometry improves heat transfer by up to 224% compared with a flat surface configuration. The triangular-shaped heating surface is the most effective in enhancing both heat transfer and flow strength. In general, flow strength and heat transfer increase with rising Ram and decrease with increasing Da and Ha. The study also proposes a mathematical correlation to predict thermal characteristics by integrating all geometric and flow control variables.Research limitations/implicationsThe present concept can be extended to further explore thermal performance with different curvature effects, orientations, boundary conditions, etc., numerically or experimentally.Practical implicationsThe present geometry configurations can be applied in various engineering applications such as heat exchangers, crystallization, micro-electronic devices, energy storage systems, mixing processes, food processing and different biomedical systems (blood flow control, cancer treatment, medical equipment, targeted drug delivery, etc.).Originality/valueThis investigation contributes by exploring the effect of various geometric shapes of the heated bottom on the hydromagnetic convection of Cu–Al2O3–H2O hybrid nanofluid flow in a complex umbrella-shaped porous thermal system involving curved surfaces and multiphysical conditions.
Natural convection of a reacting hybrid nanofluid in an open porous cavity bounded by vertical wavy wallsRoy, Nepal Chandra; Monira, Sherajum
2023 International Journal of Numerical Methods for Heat and Fluid Flow
doi: 10.1108/hff-02-2023-0056
The purpose of this study is to investigate the natural convection characteristics of a reacting hybrid nanofluid in an open porous cavity bounded by vertical wavy walls subject to an inclined magnetic field.Design/methodology/approachThe physical domain of the problem is constructed using coordinate transformations, and the equations are transformed accordingly. The resulting equations are then solved using finite difference method. Numerical results for the streamlines, isotherms and isoconcentration are illustrated with varying relevant parameters.FindingsWhatever the values of parameters, streamlines have two counter-rotating cells, and their intensities are the highest near the open end. Moreover, the maximum temperature and the minimum concentration are obtained in close proximity to the open end. The strength of streamlines is increased with increasing Rayleigh number, Frank-Kamenetskii number and Darcy number, whereas it is decreased with the increment of volume fractions of nanoparticles.Research limitations/implicationsThe limitations of this study are that the model is suitable for thermal equilibrium cases and constant thermo-physical properties, while the results can predict two-dimensional flow behaviors.Originality/valueTo the best of the authors’ knowledge, there is no study on the natural convection induced by a chemical reaction in an open cavity bounded by vertical wavy walls. The findings might be used to gather knowledge about the flow, energy and reactant distributions in an open space containing a chemical reaction.
Magneto-bioconvection flow in a porous annulus between circular cylinders containing oxytactic microorganisms and NEPCMAlsedais, Noura; Al-Hanaya, Amal; Aly, Abdelraheem M.
2023 International Journal of Numerical Methods for Heat and Fluid Flow
doi: 10.1108/hff-02-2023-0095
This paper aims to investigate magnetic impacts on bioconvection flow within a porous annulus between an outer cylinder and five inner cylinders. The annulus is filled by oxytactic microorganisms and nano-encapsulated phase change materials.Design/methodology/approachThe modified ISPH method based on the time-fractional derivative is applied to solve the regulating equations in Lagrangian dimensionless forms. The pertinent factors are bioconvection Rayleigh number Rab (1–100), circular cylinder’s radius Rc (0.1–0.3), fractional time derivative α (0.95–1), Darcy parameter Da (10−5–10−2), nanoparticle parameter ϕ (0–0.1), Hartmann number Ha (0–50), Lewis number Le (1–20), Peclet number Pe (0.1–0.75), s (0.1–0.9), number of cylinders NCylinders (1–4), Rayleigh number Ra (103–106) and fusion temperature θf (0.005–0.9).FindingsThe simulations revealed that there is a strong enhancement in the velocity field according to an increase in Rab. The intensity and location of the phase zone change in response to changes in θf. The time-fractional derivative a acting on a nanofluid velocity and flow characteristics in an annulus. The number of embedded cylinders NCylinders is playing a significant role in the cooling processes and as NCylinders increases from 1 to 4, the velocity field’s maximum reduces by almost 33.3%.Originality/valueThe novelty of this study is examining the impacts of the magnetic field and the presence of several numbers of embedded cylinders on bioconvection flow within a porous annulus between an outer cylinder and five inner cylinders.
Numerical study on shell and tube heat exchangers with different baffles configurationsYoucef, Ahmed; Saim, Rachid; Öztop, Hakan F.
2023 International Journal of Numerical Methods for Heat and Fluid Flow
doi: 10.1108/hff-01-2023-0006
The purpose of this paper is to give a comparison between different type of baffles for a better application. Computational analysis of heat transfer and fluid flow through plain, flower and perforated baffles for heat exchanger.Design/methodology/approachNumerical simulations for heat exchangers with plain, flower and perforated baffles are carried out with finite volume method. The thermal-hydraulic performance for the three types is presented in the same conditions.FindingsThe perforated baffles generate low shell pressure with high Nusselt number; transverse baffles give the best heat transfer with high pumping power. The overall performance coefficient of these three types of heat exchangers shows that the perforated baffles have a highest and the transverse baffles have the lowest. Analysis of the results show that perforated transverse baffles produce pressure drop lower by 6.68% than transverse baffles and 2.64% lower than flower baffles. The pumping power for perforated transverse baffles lower by 13.3% to the transverse baffles and 4.72% lower than that of flower baffles. The Nusselt number for perforated baffles higher by 4.16% to the flower baffles and 2.77% with transverse baffles. The overall performance factor in the heat exchanger with perforated baffles higher by 5.55% to that with transverse baffles and 3.46% with flower baffles. Recirculation areas are reduced in shell with perforated baffles and velocity distribution becomes more uniform.Originality/valueUsing of perforated baffles in heat exchanger give the best overall performance factor.
Numerical and experimental study of natural convection heat transfer on flat and corrugated platesVerdério Júnior, Sílvio Aparecido; Coelho, Pedro J.; Scalon, Vicente Luiz; del Rio Oliveira, Santiago
2023 International Journal of Numerical Methods for Heat and Fluid Flow
doi: 10.1108/hff-03-2023-0132
The purpose of this study is to numerically and experimentally investigate the natural convection heat transfer in flat plates and plates with square, trapezoidal and triangular corrugations.Design/methodology/approachThis work is an extension of the previous studies by Verderio et al. (2021a, 2021b, 2021c, 2021d, 2022a). An experimental apparatus was built to measure the plates’ temperatures during the natural convection cooling process. Several physical parameters were evaluated through the experimental methodology. Free and open-source computational tools were used to simulate the experimental conditions and to quantitatively and qualitatively evaluate the thermal plume characteristics over the plates.FindingsThe numerical results were experimentally validated with reasonable accuracy in the range of studied RaLP for the different plates. Empirical correlations of Nu¯LPexp=f(RaLP), h¯conv=f(RaLP) and Nu¯LPexp⋅(A/AP)=f(RaLP), with good accuracy and statistical representativeness, were obtained for the studied geometries. The convective thermal efficiency of corrugated plates (Δη), as a function of RaLP, was also experimentally studied quantitatively. In agreement with the findings of Oosthuizen and Garrett (2001), the experimental and numerical results proved that the increase in the heat exchange area of the corrugations has a greater influence on the convective exchange and the thermal efficiency than the disturbances caused in the flow (which reduce h¯conv). The plate with trapezoidal corrugations presented the highest convective thermal efficiency, followed by the plates with square and triangular corrugations. It was also proved that the thermal efficiency of corrugated plates increases with RaLP.Practical implicationsThe results demonstrate that corrugated surfaces have greater thermal efficiency than flat plates in heating and/or cooling systems by natural convection. This way, corrugated plates can reduce the dependence on auxiliary forced convection systems, with application in technological areas and Industry 4.0.Originality/valueThe empirical correlations obtained for the corrected Nusselt number and thermal efficiency for the corrugated plate geometries studied are original and unpublished, as well as the experimental validation of the developed three-dimensional numerical code.