Maximum Value Of Heat Flux Research Articles

Thermal conductivity impact on MHD convective heat transfer over moving wedge with surface heat flux and high magnetic Prandtl number

The present evaluation focused on heat transfer and magnetic flux along the moving non-conducting wedge shape with thermal conductivity and surface heat flux effects. A suitable and well-known similarity transformation for integration is used for the coupled non-linear partial differential equations with stream formulations. The Keller Box technique is utilized to integrate the final non-similar equations numerically. The discretized algebraic equations are displayed graphically and numerically using the MATLAB software. The physical characteristics like temperature, magnetic field, velocity profiles, skin friction, heat transfer and magnetic intensity are investigated with various factors. The influence of relevant characteristics like thermal conductivity ξ, Prandtl number Pr, wedge parameter β, variable viscosity ε, and Biot number Bi is interpreted graphically and numerically. It is noted that velocity graph effects are declined at lower value of Biot number and enhanced value is obtained at the higher value of Biot number. The fluid temperature with highest thermal slip effects is displayed with minimum value of thermal conductivity but minimum value is obtained at large value of thermal conductivity. The maximum heat flux value is obtained at large value of moving parameter.

Heat Transfer Process of the Tea Plant under the Action of Air Disturbance Frost Protection

Wind machines based on the air disturbance method are progressively employed to mitigate frost damage within the agricultural machinery frost protection. These devices are utilized during radiative frost nights to disrupt near-surface thermal inversion through air mixing. Despite this application, the fundamental mechanisms underlying these mixing processes are not well comprehended. In this research, numerical simulations were conducted using COMSOL Multiphysics software version 6.0 to simulate the flow and heat transfer processes between the thermal airflow and both the tea canopy and stems. The results indicated that due to obstruction from the canopy cross-section, the airflow velocity on the contact surface rapidly increased. As the airflow further progressed, the high-speed region of the airflow gradually approached the canopy surface. Turbulent kinetic energy increased initially on the windward side of the canopy cross-section and near the top interface. On the windward side of the canopy, due to the initial impact of the thermal airflow, rapid heating occurred, resulting in a noticeable temperature difference between the windward and leeward sides within a short period. In the interaction between airflow and stems, with increasing airflow velocity, fluctuations and the shedding of wake occurred on the leeward side of the stems. The maximum sensible heat flux at the windward vertex of the stem increased significantly with airflow velocity. At an airflow velocity of 2.0 m/s, the maximum heat flux value was 2.37 times that of an airflow velocity of 1.0 m/s. This research utilized simulation methods to study the interaction between airflow and tea canopy and stems in frost protection, laying the foundation for further research on the energy distribution in tea ecosystem under the disturbance of airflow for frost protection.

Fabric handling evaluation of woven shirting fabrics by the fabric touch tester

A fabric touch tester is a novel instrument with fabric handling properties. Its principal advantage is that the device has integrated modules for compression, surface friction, and thermal and bending properties. This module integration simplifies the testing process, and provides an efficient measurement method, and a comprehensive physical index. This study focused on woven fabrics for dress shirts. The fabric samples comprised three groups with various yarn compositions – that is, cotton, polyester, and wool. Sample group 1 was composed of cotton, polyester, and blended yarns; sample group 2 mainly compared the effect of twist yarns on the fabric touch; and sample group 3 was composed of wool and blended yarns with polyester. The handling properties were assessed by compression work and the compression recovery rate for the compression attributes. The results revealed that fabric (T100p1) with high twist-level yarns had a higher value of compression work (242.56 gf*mm2), and the texture type may affect the compression characteristics more significantly than the blending ratio. The fabric touch tester can also distinguish small changes in the compression properties of samples (0.43–0.71), the maximum heat flux and surface roughness amplitude for the thermal and surface roughness properties. The results revealed that the maximum heat flux value of all the samples in this study was 1109 Wm−2, the sample C100 using pure cotton yarn had the highest maximum heat flux value (1270 Wm−2). Moreover, the sample W100 with 100% wool fiber yarn had the highest surface roughness amplitude in the warp direction (81 μm) and surface roughness amplitude in the weft direction (67 μm). Finally, the bending average rigidity was used to assess the bending performance of the fabric samples. These fabric touch tester indicators were applied to analyze the fabric handling characteristics of woven shirting fabrics, and perform cross-analysis among samples.

Thermo-Mechanical Behavior of Aluminum Matrix Nano-Composite Automobile Disc Brake Rotor Using Finite Element Method.

Analysis of mechanical and thermal behaviors during braking has become an increasingly important issue in many transport sectors for different modes of transportation. Brake failure generated during braking is a complex phenomenon confronting automobile manufacturers and designers. During braking, kinetic energy is transferred to thermal energy, resulting in the intense heating of disc brake rotors that increases proportionally with vehicle speed, mass, and braking frequency. It is essential to look into and improve strategies to make versatile, thermally resistant, lightweight, high-performance discs. As a result, this study uses the finite element method to conduct a thermo-mechanical analysis of aluminum alloy and aluminum matrix nano-composite disc brake rotors to address the abovementioned issues. The FEA method is used for the thermo-mechanical analysis of AMNCs for vented disc brake rotor during emergency braking at 70 km/h. From the results obtained, aluminum base metal matrix nano-composites have an excellent strength-to-weight ratio when used as disc brake rotor materials, significantly improving the discs’ thermal and mechanical performance. From the result of transient thermal analysis, the maximum value of heat flux obtained for aluminum alloy disc is about 8 W/mm2, whereas for AMNCs, the value is increased to 16.28 W/mm2. The result from static analysis shows that the maximum deformation observed is 0.19 mm for aluminum alloy disc and 0.05 mm for AMNCs disc. In addition, the maximum von Mises stress value of AMNC disc is about 184 MPa. The maximum von Mises stress value of aluminum alloy disc is about 180 MPa. Therefore, according to the results, the proposed aluminum base metal matrix nano-composites are valid for replacing existing materials for disc brake rotor applications.

Electrothermal Simulation and Optimal Design of Thermoelectric Cooler Using Analytical Approach

In this article, electrothermal modeling and simulation of thermoelectric cooling (TEC) in the package design of VLSI systems are performed by solving coupled heat conduction and current continuity equations. We propose a new analytical solution to the coupled partial differential equations (PDEs) which describe temperature and voltage with the reduction from 3-D to 1-D. In addition to this, we derive new analytic expressions for two key performance metrics for TEC devices: 1) the maximum temperature difference and 2) the maximum heat-flux pumping capability, which can be guided for the optimal design of thermoelectric cooler to achieve the maximum cooling performance. Furthermore, for the first time, we observe that when the dimensionless figure of merit <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$ZT_{0}$ </tex-math></inline-formula> value is larger than 1, there is no maximum heat-flux value, which means the heat dissipation due to the Peltier and Fourier transfer effects is larger than the heat generation caused by the Joule heating effect, which can lead to more efficient TEC cooling design. The accuracy of the proposed 1-D formulas is verified by a 3-D finite element method using COMSOL software. The compact model delivers many orders of magnitude speedup and memory saving compared to COMSOL with marginal accuracy loss. Compared with the conventional simplified 1-D energy equilibrium model, the proposed analytical coupled multiphysics model is more robust and accurate.

Simulation and optimization of lightweight insulating geopolymer composites via dual gradient slurry deposition

High porosity over 50% is essential to achieving lightweight and thermal insulating properties in the green manufacturing of geopolymers. Recognizing that mechanical and thermal properties are highly related to pore distribution and orientation, we analyze and optimize the pore of the geopolymer composites with purposely designed different gradient variations via additive manufacturing (AM) and simulate the related properties. The results shows that adding 15 wt% diamond in the specimen reduced the heat flux and the maximum value of heat flux at 15 wt% part is 13.429 J/s. The dynamic nano hardness and Young's modulus values both increase with increasing diamond ratios in addition to the 12 wt%. Besides, the elongated shape of internal pores and throat is closely related to the layer-stacking printing method, playing a more significant role than material in the decreased thermal and ductile compressive behavior. 3D structure of Schwarz w with connected pores is proved to have the optimal mechanical and thermal performances among the eight typical triply periodic structures. This research establishes the guidelines to the pore analysis and simulation of multiple mineral composites with tailored, deigned-pore-dependent lightweight and thermal insulation properties.

Effect of Wood Flour Addition on Warm/Cool Feeling of Green Composite

In this study, effect of wood flour addition on warm/cool feeling of green composite using wood flour and poly(lactic acid) was investigated for comfortability of interior product. Additive amounts of wood flour were 10 – 40 wt.%. Measurement of initial maximum values of heat flux of green composite using wood flour was conducted under constant temperature and humidity chamber. Surface of green composite using wood flour was observed by Scanning Electron Microscope (SEM). Following conclusions were obtained. The initial maximum value of heat flux of green composite decreased with an increase of wood flour additive amount until 20 wt.%. But, initial maximum value of heat flux of green composite at more than wood flour additive amount 30 wt.% almost did not change. From SEM observation, the appearance void area on surface of green composite at wood flour additive amount 20 wt.% was larger than that of green composite at wood flour additive amount 10 wt.%. Therefore, initial maximum value of heat flux of green composite was mainly affected because of increase of void area and wood flour until wood flour additive amount 20 wt.%.

Multi-nozzle spray cooling of a reactor pressure vessel steel plate for the application of ex-vessel cooling

Spray cooling is a versatile technology for various cooling applications involving high surface heat fluxes. Experimental facility was built to study heat transfer performance of an upward multi-nozzle array of water sprays impacting a surface of heated plate made of reactor vessel grade steel. The effect of inclination angles of the steel surface on the cooling performance was investigated to assess heat transfer in complex semispherical/semielliptical geometry of large reactor lower head and to address possible application of spray cooling in severe accident management (SAM) of light water reactors (LWRs) based on In-vessel melt retention with external reactor vessel cooling (IVR-ERVC). Joule heating of SA302B steel foil of 0.15 mm thickness and surface area of 96 cm2 enabled prototypic heat fluxes to be evacuated during reactor accident. A 2 × 3 array of full jet narrow-coned pressure-swirl spray nozzles was used to reproduce multi-nozzle cooling. The tests were conducted as a series of consequent steady states realized at stepwise increasing power and surface heat fluxes up to the maximum values of 29 kW and 2.97 MW/m2 limited in the specific facility design. Seven surface inclinations, between 0° and 90° were tested and no significant variations in spray cooling performance with the inclination of the heated surface was found. The results indicated a promising prospect of using a multi-nozzle array system for cooling of large surface area of reactor lower head. Much higher heat fluxes can be safely extracted by spray cooling in comparison with the critical heat fluxes that appeared at RPV water pool cooling at natural convection. The maximum value of heat flux at direct spray impact zones and its drop-off slightly from the center to the periphery of the spray cone was detected in the tests. The water flow rate and liquid subcooling significantly influenced maximum steel surface temperature but had no noticeable effects on surface temperature uniformity. The spray-to-spray interaction had no observable effects on local surface temperatures, however, the colliding zones where four spray cones have visible effects on local surface temperatures due to poor liquid momentum. The results also showed that more uniform liquid film distribution could be obtained for some inclinations because of improved liquid drainage, which in turn leads to maintaining low surface temperatures.

Критичні теплові потоки при кипінні в умовах капілярного транспорту у двофазних системах термостабілізації

The increase in heat generated by electronic components requires a need to expand the range of two-phase heat exchangers for thermal stabilization of the components. The efficiency of the two-phase systems (heat pipes, steam chambers) can be improved by using metal-fiber capillary-porous structures. Experimental studies for the conditions close to the operating conditions of heat pipes and vapor chambers described in known publications are rather incomplete. The aim of this study is to determine the boundary heat fluxes for water boiling on porous structures under capillary soaking, to investigate the influence of saturation pressure and structural parameters on the boundary heat fluxes, and to determine the optimal structural parameters of porous samples, i.e. such parameters that would allow the highest possible values of critical heat fluxes under given conditions. The authors investigate 0.3 and 0.5 mm thick capillary structure samples made of copper fibers with a diameter of 10 to 50 μm and a porosity range of 65—85%. The study has found that reducing the saturation pressure from 0.1 to 0.012 MPa leads to a decrease in the boundary heat flux values by 15—40%, depending on the effective pore diameters. The study allowed establishing that the maximum heat flux values are achieved for the samples with an effective pore diameter of 60 to 80 μm. It was also found that for the 0.5 mm thick samples, the boundary heat fluxes are 5—20% higher than for the 0.3 mm thick samples. The decrease in saturation pressure has been found to lead to a decrease in the range of two-phase heat exchange systems. For a number of samples, the authors have obtained the optimal effective pore diameters ensuring the highest critical heat flux values in the studied range.

Influence of the Longitudinal Magnetic Field on the Formation of the Bead in Narrow Gap Gas Tungsten Arc Welding

The oscillation arc assisted by an extra alternating longitudinal magnetic field (LMF) in narrow gap tungsten arc welding is proved to be effective in avoiding welding defects due to insufficient fusion at the side walls in joining thick wall plates. The behavior of the welding arc and molten pool under the LMF is simulated to reveal the influence of the LMF on the formation of a uniform penetration weld bead. A unified mathematical model was developed for the narrow gap tungsten arc welding including the plasma arc, molten pool, electrode, and their interactions. Under the LMF, the whole welding arc is deflected and oscillates between the two side walls. When the magnetic-field strength is larger than 6 mT, the axis of the arc deflects to the side wall; the maximum value of heat flux at the bottom decreases by one-half, and the maximum value at the side wall is increased by a factor of ten. On the other hand, under the LMF, the forces acting on the molten pool are changed; the fluid flow pattern is helpful to increase the heat transferred to the side walls. The model is validated by experimental results. Both the percentage deviations of the simulation weld penetration at the side wall and at the bottom from the experimental results are lower than 10%.

Experimental investigation of underground seasonal cold energy storage using borehole heat exchangers based on laboratory scale sandbox

In order to overcome the intermittent nature of renewable energy resources, borehole thermal energy storage (BTES) systems are found to be a feasible option these days. Previous research data shows that most of the BTES projects are related to heat storage and there are very few underground cold storage applications. The proposed research work is based on the experimental strategy to determine the extracted energy storage potential in typical weather condition areas. It emphasizes on the mathematical model for soil extracted energy storage system and derives similar function relationship of soil TES system based on similarity theory. A laboratory-scale sandbox is designed with similar scale factor n = 20. Sandbox system is operated in peak winter months from October to March according to the weather data for Dunhuang, China. Approximately 69 % of the input energy is charged into the soil. Soil temperature is reduced up to 11 °C during the extraction period. The maximum heat flux value is recorded 65 W.m−2. The experimental results reveal the practicality of proposed research method. It can be used to fulfill cooling load requirements for air conditioning systems and solar thermal power plants located in desert areas with water shortage issues.

Fouling in a Steam Cracker Convection Section Part 2: Coupled Tube Bank Simulation using an Improved Hybrid CFD-1D Model

Performing an adequate fouling study for the heat exchangers in the convection section of a steam cracker requires reliable data on circumferential tube wall temperature profiles. A hybrid Computational Fluid Dynamics (CFD)-1D convection section model, developed to perform coupled flue gas/process gas side simulations of convection sections, is improved by the implementation of flue gas radiation modeling and extended to include typical tube banks. A complete naphtha cracker convection section is simulated with the improved hybrid CFD-1D model. All tubes show distinct maximum heat fluxes on the tube walls due to the high flue gas velocity. Based on the calculated circumferential heat flux profiles, the maximum heat flux value is calculated to be 1.8 times the average tube heat flux value. As computational costs associated with a hybrid CFD-1D simulation are high, a convective heat flux profile reconstruction scheme is developed. Using the scheme, circumferential heat flux profiles are reconstructed, based on the heat fluxes calculated when performing a fully 1D coupled convection section simulation. The heat flux reconstruction profile scheme enables fast retrieval of circumferential heat flux profiles and, thus, tube wall temperature profiles. Optimization and/or design of a steam cracker convection section becomes less computationally demanding.

Two-Phase Performance of a Hybrid Jet Plus Multipass Microchannel Heat Sink

Abstract The heat transfer and fluid flow performance of a hybrid jet plus multipass microchannel heat sink in two-phase operation is evaluated for the cooling of a single large area, 3.61 cm2, heat source. The two-layer branching microchannel heat sink is evaluated using HFE-7100 as the coolant at three inlet volumetric flow rates of 150, 300, and 450 ml/min. The boiling performance is highest for the flow rate of 450 ml/min with the maximum heat flux value of 174 W/cm2. Critical heat flux (CHF) was observed at two of the tested flow rates, 150 and 300 ml/min, before reaching the maximum operating temperature for the serpentine heater. At 450 ml/min, the heater reached the maximum allowable temperature prior to observing CHF. The maximum pressure drop for the heat sink is 34.1 kPa at a heat flux of 164 W/cm2. Further, the peak heat transfer coefficient value of the heat sink is 28,700 W/m2 K at a heat flux value of 174 W/cm2 and a flow rate of 450 ml/min. Finally, a validated correlation of the single device cooler is presented that predicts heat transfer performance and can be utilized in the design of multidevice coolers.

Effects of cutting parameters on tool temperatures in intermittent turning with the formation of serrated chip considered

Taking the formation of serrated chip into account, a theoretical method for prediction of tool temperatures in intermittent turning was proposed to reveal the effects of cutting parameters on tool temperatures. The evolution of heat flux during the formation of saw-tooth chip was analyzed. Based on the established analytical model, the development of transient average tool temperatures with cutting time was investigated. The mean values of transient average tool temperatures were obtained and the effects of cutting parameters on tool temperatures were revealed. It was found that feed rate and depth of cut had greater effects on the maximum value of heat flux in saw-tooth chip formation than they did on the minimum value. Because of the alternation of cutting periods and non-cutting periods, the transient average tool temperature evolved cyclically with the cutting time in the whole cutting process. Tool temperatures developed cyclically with the cutting time in the cutting period due to the periodical formation of saw-tooth chip. Compared to the final stage of cutting period, tool temperature increased much more quickly in the initial stage. Relatively large feed rate and relatively small depth of cut should be adopted to acquire the lowest tool temperature.

Experimental investigation on the heat transfer characteristics of vacuum spray flash evaporation cooling

Vacuum spray flash evaporation cooling (VSFEC) is considered as an alternative effective method for dissipating high heat flux in the field of space thermal control. In this paper, a VSFEC experiment system has been developed to investigate the influence of spray flow rate and spray height on the heat transfer characteristics of VSFEC. The experiment results show that the heat flux can be removed efficiently from the heat source in VSFEC system with a very small spray flow rate, which is only one third of that of conventional spray cooling under the same heat flux. And an optimal flow rate exists in VSFEC, at which the heat transfer approaches to a highest value, it is different from conventional spray cooling in which the heat flux increases with the increasing of spray flow rate all the time, in VSFEC, the heat flux firstly increases and then decreases with increasing of flow rate. Since VSFEC system is an open-loop heat dissipation system, it has very important significance that based on the optimal flow rate to reduce working medium consumption, especially for space thermal control system which has a strict limit on weight. In addition, spray height has an important effect on the heat transfer characteristics of VSFEC and an optimal spray height is also obtained at which the maximum value of heat flux can be achieved.

A fractal dropwise condensation heat transfer model including the effects of contact angle and drop size distribution

In this paper, a new dropwise condensation heat transfer model is developed on the basis of Rose model for a drop heat transfer and random fractal functions for the drop size distributions of direct condensation drops and coalescence drops. Compared to the well-established Rose’s model, the new model considers the contact angle and its hysteresis, the nucleation site density, the fractal dimension for drop sizes and maximum and minimum drop radii. Expressions of the distributions functions for both the direct condensing drops and the coalescence drops are derived and calculated by introducing fractal theory, respectively. The total heat flux of dropwise condensation on the entire condensing surface is calculated as the sum of the contributions from the condensations of above mentioned two kinds of drops. The simulation results indicate that the fractal dimension for drop sizes distribution decreases with increase in contact angle, resulting in smaller departure diameters and even shorter life cycle, which plays an active role in higher heat transfer coefficients. But the decline of fractal dimension leads to the decrease in the number density of droplets, which has negative effects on heat transfer process. Attributing to the combined influences mentioned above, the maximum heat flux value is obtained at θ=135°. The model proposed is applicable to predict the heat flux of the condensing drops with a wide range of contact angles, and the prediction results can agree well with different experimental dropwise condensation heat transfer data obtained from experiments and majority of literature results by choosing the proper contact angle parameters. The study can also reasonably explain the cause of the diversities of the dropwise condensation heat transfer data from different references.

密度が異なる極細繊維インターロックの しっとり感に対する日中比較

Japanese and Chinese students evaluated the “shittori” feeling for knitted fabrics with different stitch density. In Hong Kong, we used the expression of “Baby’s skin” to explain “shittori” sensation. The mechanical, surface properties and air resistance, the maximum value of heat flux, qmax were measured by using the KES system. In Japan, subjects felt the stronger “shittori” feeling of knitted fabrics, which have larger value of stitch density in this study. The stronger “shittori” feeling of fabrics is also derived from fabric properties, such as the large values of MIU (coefficient of friction), B (bending rigidity), G (shear stiffness), 2HG (hysteresis of shear force at 0.5°of shear angle) and Air Resistance. In Hong Kong, subjects felt stronger “shittori” feeling for the smaller stitch density fabric. Also the stronger “shittori” feeling of students in Hong Kong was related to the small values of G, 2HG, B and 2HB (hysteresis of bending moment) of fabrics.

Heat and mass transfer of adult incontinence briefs in computational simulations and objective measurements

This study aims to evaluate the heat and mass transfer of two kinds of multilayer adult incontinence briefs (diapers for short) in the dry condition and dynamic heat and moisture transfer processes in the wet condition in computational simulations and objective measurements. A commercial disposable brief (PROTEC) with polyethylene, superabsorbent polymers (SAP) and polypropylene, and another kind reusable brief (Reusable) with waterproof breathable fabric, full cotton inner pad and moisture management treatment nonwoven were evaluated. A software platform (S-smart system) with user friendly interfaces was employed in computational simulations. Wear trials were conducted by asking young female adults between 20 and 26 years old to wear incontinence briefs. Objective measurements revealed that there was significantly higher liquid moisture management capacity, water vapor permeability, thermal conductance and maximum value of heat flux in the Reusable than in PROTEC briefs. The simulation and wear trial results showed that there were significantly lower temperatures and humidity at the skin in the diaper area and diaper inner surface fabric in the Reusable briefs compared to the PROTEC ones. The good agreement between simulations and wear trials were observed. The 2D and 3D directly visualizes the changes of fabric temperature/humidity gradient and capacity of absorbing moisture etc. in each layer. The results indicate that the superior fabric’s heat/moisture transporting properties, when incorporated into diapers, is the main mechanism for reducing heat and wetness of the diaper area. The results provide guidance for the optimal design of Eco-friendly diapers with reusable, breathable, biodegradable materials.

Jet Impingement Quenching: Effect of Coolant Accumulation

During quenching of wide steel plates with impinging water jets in the accelerated cooling section of a plate mill, the coolant accumulates over the plate. In this study, the effect of coolant accumulation on the heat transfer rate during jet impingement quenching has been investigated. In these experiments, the coolant accumulates over the impingement surface of the test specimen within a volume created by assembling a ceramic tube length around the test specimen. The quenching rate with and without the accumulation of coolant are compared. The propagation of the wetting front is decelerated due to the accumulation of coolant. The reduction in the jet impingement momentum as it passes through the accumulated layer of coolant and the obstruction to the radial outflow of the released vapor by the ceramic tube are the likely reasons for this observation. The maximum heat flux value, analogous to the critical heat flux condition of steady state pool boiling, decreases due to accumulation, but the corresponding temperature shows little dependence on accumulation. This study contributes to further the understanding of the jet impingement quenching process.

Dynamically Similar Studies of the Thermal Performance of Helium-Cooled Finger-Type Divertors with and Without Fins

Experimental studies based upon dynamic similarity have been used to evaluate the thermal performance of several modular helium-cooled tungsten divertor designs, including a configuration similar to the helium-cooled modular divertor with multiple jets (HEMJ). Until recently, all of these experiments used air, instead of helium, as the coolant. The average Nusselt number and loss coefficient were determined from cooled surface temperature and pressure drop data. Correlations were developed for the Nusselt number and loss coefficient as a function of the Reynolds number then used to predict the thermal performance of the divertor under prototypical conditions when cooled with high-temperature, high-pressure helium. Recently, experiments were performed using helium and argon to confirm the dynamic similarity assumption. The results indicated that the previous experiments with air, which were performed at the prototypical nondimensional coolant mass flow rate, or Reynolds number, did not account for the differences in the fraction of the incident power conducted through the walls of the divertor versus that convected, i.e., removed, by the coolant.Dimensional analysis and numerical simulations suggest that for a given divertor geometry this fraction can be characterized by the ratio of the thermal conductivities of the divertor material and the coolant. Nusselt number correlations were developed to include the effect of the thermal conductivity ratio. Based on these correlations, the predicted maximum heat flux values that can be accommodated by the HEMJ-like configuration are reduced by [approximately]20% from previous estimates. The results also suggest that the maximum heat flux that can be accommodated by this design can be increased by as much as 19% by adding an array of cylindrical pin fins on the cooled pressure boundary. However, as expected, adding the fins increases the pumping power for the coolant by [approximately]16%. As a fraction of maximum total incident thermal power, however, the pumping power decreases by 2% when the fins are added due to the significant increase in the maximum heat flux.