Heat Transfer Devices Research Articles

Copper fiber wick with scaly fins fabricated by multi-tooth cutting for directional heat transfer

Copper fiber wick with scaly fins fabricated by multi-tooth cutting for directional heat transfer

ANFIS-PSO analysis on axisymmetric tetra hybrid nanofluid flow of Cu-CNT-Graphene-Tio2 with WEG-Blood under linear thermal radiation and inclined magnetic field: A bio-medicine application.

The development of heat transfer devices used for heat conversion and recovery in several industrial and residential applications has long focused on improving heat transfer between two parallel plates. Numerous articles have examined the relevance of enhancing thermal performance for the system's performance and economics. Heat transport is improved by increasing the Reynolds number as the turbulent effects grow. Regarding heat transfer, hybrid nanofluids are superior to mono nanofluids. The hybrid fluid of Cu-CNT+Graphene+TiO2/WEG-Blood, which is subject to heat transfer in a channel between two parallel plates with an angled magnetic field and linear thermal radiation, has numerous applications in engineering, industry, and biomedical research, such as electronic cooling, drug delivery, cancer treatment, optics, missiles, satellites, transformer-electronic cooling, and military solar-equipment. Examining the qualities of mass, flow, and heat transmission is the aim of the study of a hybrid Cu-CNT- Graphene-TiO2/WEG-Blood nanofluid as it moves via a tube of porous material that is exposed to linear thermal radiation, inclined magnetic, Forchheimer, and buoyancy influences. ANFIS-PSO model is assumed. Applying the ODE45 integration technique to the given numerical solutions yields non-linear, non-dimensionalized, and highly partial differential equations that control the momentum, energy, and concentration. Consequently, the numerical simulation shows the concentration, velocity, and temperature profiles of the hybrid Cu-CNT- Graphene-TiO2/WEG-Blood nanofluid. A strong concordance is noted between recent and past results. Radiation regulates the microchannel temperature distribution, which significantly contributes to cooling the flow transport system, and the thermal radiation parameter shows that radiation has a retarding influence on the temperature profile.

Numerical Study of heat transfer performance of geothermal pile-foundation heat exchanger in ground source heat pump system

Abstract To evaluate the thermal conductivity performance of geothermal pile-based heat transfer units utilized within ground source heat pump (GCHP) frameworks, we developed physical models encompassing both solitary pile-based heat transfer devices and assemblies of such units. A thorough examination was conducted into the heat exchange mechanics and efficacy of these devices, covering both refrigerating and warming operational modes. For the purpose of simulating the heat transfer processes within a 3×3 array of energy piles, a real-world scenario involving an office building situated in Nanjing was adopted. Utilizing DeST software, we calculated the annual dynamic building load, which spans the cooling period, the heating period, and the two intervening transition periods. Following a simulated ten-year operational lifespan, it was noted that the average soil temperature exhibited an increase under conditions of non-equilibrium. The outcomes of this study closely mirror real-world conditions and can be harnessed as a theoretical foundation for the design and deployment of pile-foundation heat exchangers within GSHP systems.

COLD PLATE DESIGNS: A COMPARISON OF EVALUATION METRICS -CONSTRUCTAL SVELTENESS AND GLOBAL RESISTANCE

Cold plates are heat transfer devices used in various industries such as aerospace, automotive, and telecommunications primarily to prevent overheating and ensure efficient operation of electronics and power electronics components. They are compact, flat heat exchangers designed mainly by dissipate heat to a liquid coolant. The present paper compares the thermal performance of three serpentine arrangements using a global resistance metric that accounts for thermal resistance and pumping power. Then, various Svelteness definitions that differ in the external length scale are investigated. All the designs hold the same five degrees of freedom: plate area, plate weight, pipe diameter, pipe bend radius ratio, and plate length ratio, but only the two latter ones are investigated here. Results show that the simple “S” shape performs better regarding the global resistance metric, mainly for configurations with low values of the ratio between the bend curvature radius and the pipe diameter (R/d). The three variants of Svelteness capture the general thermal performance very well, particularly the R/d effect and the impact of the plate aspect ratio (W/d). However, none of the Svelteness definitions considered could completely capture the performance differences among the different arrangements measured with the global resistance metric.

Simulation and Experimental Study of Two-Phase Gas–Liquid Behavior in Two-Dimensional Porous Medium Based on Lattice Boltzmann Method

Abstract Loop heat pipe is a passive two-phase heat transfer device. The key component of the loop heat pipe is the evaporator. In this study, the gas–liquid two-phase behavior inside a two-dimensional porous medium with a single-pore size and multi-pore size distributions was comparatively studied, both experimentally and numerically by the lattice Boltzmann method. With a constant heat flux applied to the evaporator's shell, the wick initially fills with saturated liquid, then undergoes evaporation with vapor invasion, and partially dries out with a gas–liquid interface. Due to the multi-pore size distribution in porous medium, vapor is more easily expelled from the wick. There is a significant difference gas–liquid interface inside the wick between the single-pore size wick and the multi-pore size wick, and the temperature of the evaporator's shell of the multi-pore size wick is 27.6% lower than that of the single-pore size wick. To validate the numerical results, two loop heat pipes were built, including monoporous wick and biporous wick, respectively. The experiment found that under high power, the performance of loop heat pipe with biporous wick is significantly better than that of loop heat pipe with monoporous wick. The temperature of the biporous wick is 9.79 K lower than that of the monoporous wick at 230 W. Experiments and simulations show that the porous medium with multi-pore has better performance.

Numerical Investigation of Nanofluid-based Flow Behavior and Convective Heat Transfer Using Helical Screw

Numerous industrial and home users have made use of heat transfer devices for the purpose of heat conversion and recovery. For the past half-century, engineers have worked tirelessly to perfect a heat exchanger design that cuts down on power use without sacrificing performance. Most methods of improving heat transfer work by either increasing the effective heat transfer surface area or creating turbulence, which results in lower thermal resistance. In this study, CFD was used to simulate Al2O3 and CuO nanoparticles in the adsorber tube of a parabolic solar collector with N=1 and N=2 turbulators at Re=20000, 60000, and 100000, respectively, and a turbulence strength of 5%. The turbulence strength was calculated as 5% of the total energy of the particles. Heat conduction is improved by the presence of nanoparticles in the base fluid. Therefore, nanofluids are candidates for alternative methods of heat transfer. Torsional turbulator models with N=2 have a greater output temp than those with N=1 because N=2 models have a higher practical heat level. The intake temp is raised from 35 to 46 degrees Celsius thanks to the presence of CuO nanoparticles in the two turbulator adsorber tubes that are close to one another. The Reynolds number invariably makes the Nusselt number higher. In addition, the Nusselt number demonstrates that there are a greater number of CuO nanoparticle models than Al2O3 nanoparticle models. In addition, CuO nanoparticles are more effective than Al2O3 at lowering pressure. When compared to the N=2 dual-turbulator mode, the N=1 single-turbulator mode has 34% more conflict. PECs are greater for models with two turbulators. Over a wide range of Reynolds numbers, the thermal PEC for N=2 models were 12 percentage points higher than that of N=1 models. CuO nanofluid receivers are superior to Al2O3 ones in their ability to convert solar energy into thermal energy. The two-turbulator model with a Reynolds number of 100,000 that uses CuO nanoparticles achieves the maximum thermal efficiency.

Heat Transfer Simulation and Structural Optimization of Spiral Fin-and-Tube Heat Exchanger

The spiral fin-and-tube heat exchanger is a widely used heat transfer device in heating and cooling applications, and its performance is influenced by multiple structural parameters, including the pitch, thickness, and height of the fins, the diameter and thickness of the base tube, and the transverse and longitudinal tube spacings. This study comprehensively explores how these factors affect the heat transfer performance of the spiral fin-and-tube heat exchanger and aims to determine its optimal configuration of structural parameters. First, orthogonal experiments are arranged based on these factors to conduct the corresponding finite element numerical simulations and to determine the effects of these factors on the heat transfer and resistance performance of the spiral fin-and-tube heat exchanger. Subsequently, support vector regression (SVR) is introduced to predict the heat transfer factor and the resistance factor, with the aim of benefiting the construction of a multi-objective optimization model for optimizing the two factors simultaneously. Then, a comprehensive performance indicator is used to transform the multi-optimization problem to a single optimization problem, and the genetic algorithm is adopted to solve an optimal configuration of the heat exchanger structural parameters. Ultimately, the finite element numerical simulation is utilized to validate the accuracy of the optimization. Case studies are conducted on a specific spiral fin-and-tube heat exchanger. After the optimization, the heat transfer factor is improved by 44.44%, and the resistance factor is increased by 14.19%. However, the comprehensive performance indicator is increased by 38.79%.

Entropy generation and sensitivity analysis for a squeezed flow of a Williamson hybrid nanofluid under the supervision of microcantilever sensor

Entropy generation and sensitivity analysis for a squeezed flow of a Williamson hybrid nanofluid under the supervision of microcantilever sensor

TASA formulation for nonlinear radiative flow of Walter-B nanoliquid invoking microorganism and entropy generation

TASA formulation for nonlinear radiative flow of Walter-B nanoliquid invoking microorganism and entropy generation

Thermal Performance Investigation of Vapor Chamber Under Partial Heating and Different Heat Flux Conditions: Effects of Inclination Angle

Abstract The need for cooling technologies increases tremendously with raising demand on the powerful and compact electronics. There, it pushes the research and technology to the new investigations on varying heat transfer mechanisms and devices. While one of these devices is vapor chamber (VC), an experimental study has been carried out to investigate the heat transfer performance of a VC under partial heating, varying heat fluxes, and different inclination angles for different temperatures, in the current study. For this purpose, a VC with a dimension of 90 mm × 90 mm × 3 mm is evaluated via its resulting thermal resistance, performance, and the temperature distribution over the VC surface. There, the limited effect of inclination angle is observed on the performance, while the highest change is obtained with decreasing local heating surface area, thus increasing heat fluxes. Moreover, this trend is seen almost similar with a reasonable shift up or down according to the different temperature differences.

Experimental characterisation and visualisation of a novel two-phase flexible heat transfer device

Experimental characterisation and visualisation of a novel two-phase flexible heat transfer device

Thermal management and power generation characteristics in a bifurcating channel by using a piezo-embedded inclined elastic fin assembly during turbulent forced convection of ternary nanofluid

Thermal management and power generation characteristics in a bifurcating channel by using a piezo-embedded inclined elastic fin assembly during turbulent forced convection of ternary nanofluid

ВЛИЯНИЕ ТЕПЛОФИЗИЧЕСКИХ СВОЙСТВ ТЕПЛОНОСИТЕЛЕЙ НА ПРОЦЕСС ТЕПЛООБМЕНА В ЗАМКНУТЫХ ДВУХФАЗНЫХ ТЕПЛОПЕРЕДАЮЩИХ СИСТЕМАХ

The analysis of low-temperature heat carriers (ozone-safe freons) properties for use as heat carriers in thermosyphon elements has been carried out. The most significant thermophysical properties of heat carriers that affect the intensity of heat exchange in closed two-phase heat-transfer devices have been determined. The calculation of the FOM quality index of the heat carrier for the selected freons is given. The dependence of the thermal resistance of the thermosyphon element on the supplied heat load is established. Recommendations are given for choosing a heat carrier for two-phase heat-transfer elements

Enhancing Capillary Pressure of Porous Aluminum Wicks by Controlling Bi-Porous Structure Using Different-Sized NaCl Space Holders.

Capillary pressure and permeability of porous media are important for heat transfer devices, including loop heat pipes. In general, smaller pore sizes enhance capillary pressure but decrease permeability. Introducing a bi-porous structure is promising for solving this trade-off relation. In this study, the bi-porous aluminum was fabricated by the space holder method using two different-sized NaCl particles (approximately 400 and 40 μm). The capillary pressure and permeability of the bi-porous Al were evaluated and compared with those of mono-porous Al fabricated by the space holder method. Increasing the porosity of the mono-porous Al improved the permeability but reduced the capillary pressure because of better-connected pores and increased effective pore size. The fraction of large and small pores in the bi-porous Al was successfully controlled under a constant porosity of 70%. The capillary pressure of the bi-porous Al with 40% large and 30% small pores was higher than the mono-porous Al with 70% porosity without sacrificing the permeability. However, the bi-porous Al with other fractions of large and small pores did not exhibit properties superior to the mono-porous Al. Thus, accurately controlling the fractions of large and small pores is required to enhance the capillary performance by introducing the bi-porous structure.

Operation characteristics and limitations of small-diameter two-phase closed thermosyphon

Operation characteristics and limitations of small-diameter two-phase closed thermosyphon

Thermal performance analysis and optimization of a heat pipe-based electronic thermal management system using experimental data-driven neuro-genetic technique

Thermal performance analysis and optimization of a heat pipe-based electronic thermal management system using experimental data-driven neuro-genetic technique

Dry spot propagation during boiling crisis on thin metal heaters

Dry spot propagation during boiling crisis on thin metal heaters

Multiple slip nonlinear radiative bioconvective flow of nanofluid with variable thermal conductivity

Owing to the improved thermal applications of nanomaterials, various applications have been suggested in various era of engineering including heat transfer devices, chemical processes, thermal management devices, electronic cooling etc. The aim of current investigation is to presents the bioconvective flow of nanofluid with applications of multiple slip effects. The motivations for considering the slip effects for heat and mass transfer analysis are associated to its significance in the petroleum sciences, extrusion processes, oil recovery and plasma physics. The nonlinear thermal radiation effects and chemical reaction consequences have been attributed. In contrast to traditional investigations, the thermal conductivity of nanofluid have been assumed to be temperature dependent. Following the assumptions of dimensionless variables, a system of nonlinear differential equations is obtained. The shooting technique is employed for computing the numerical simulations. The accuracy of solution is ensured. The physical assessment of problem is incorporated in view of involved parameter. It has been claimed that interaction of slip effects enhances the heat and mass transfer effects. Change in microbes density slip parameter leads to improvement in the microorganisms profile. Moreover, local Nusselt number and Sherwood number reduces for slip parameters. Current results present significance in heat transfer systems, thermal engineering, chemical engineering, fertilizers, biofuels etc.

Analysis of peristalsis transport in flow of non-Newtonian fluid with modified Darcy’s law

Nanofluids present novel applications in various era of engineering and medical sciences like lubricants, medication delivery, cancer treatment, and microchip cooling. Investigating the peristaltic transport of a magnetohydrodynamic (MHD) Williamson nanofluid model in a horizontally asymmetrical channel is the main goal of this article. A porous medium allows the flow to take place according to the revised Darcy’s law. Hybrid nanoparticles based on aluminum oxide are used to improve the thermal properties. The classical aspects with implementation of Buongiorno approach namely thermophoretic effects and Brownian impact is elaborated. The extension in heat equations is proceeded with utilization of Joule heating and viscous dissipation outcomes. There are no-slip conditions linked to the channel borders. By adhering to the lubricating strategy and employing the homotopy perturbation method, the issues are resolved. Graphs and tables are used for physical analysis of the relevant parameters. It is examined that velocity profile enhances due to Darcy parameter in both channel walls. The temperature profile for hybrid nanofluid increases for Brinkman number. Low concentration profile is claimed for activation energy parameter. Current results incorporate the applications in thermal engineering, nuclear systems, roller pumps, heat transfer devices, chemical engineering, etc.

Silicon-based microscale-oscillating heat pipes for high power and high heat flux operation

Microscale-oscillating heat pipes (micro-OHPs) have recently drawn interest for electronic cooling applications due to their compact size and passive operating mechanism. The occurrence of dryout in OHPs, however, at which the working liquid no longer wets the evaporator, limits the maximum operating cooling power, preventing their integration for direct cooling of high heat flux semiconductor chips. Here, we report on high power and high flux operation of silicon-based OHPs by using microchannels with hydraulic diameters of ∼200 μm. Particularly, a micro-OHP with 100 μm channel height is shown to effectively operate at 210 W using a dielectric working fluid, corresponding to an unprecedented cooling power density of 145 W/cm2, without dryout. A distinctive oscillating mode with highly periodic bulk circulations occurs at high heating power and can provide efficient heat dissipation. The flow speed of the liquid under this bulk circulation mode can be as high as 10 m/s. The empirical relationships between the heat transfer rate, oscillating frequency, and device temperatures are studied.