Maximum Convective Heat Transfer Research Articles

Enhancing heat transfer performance in forced convective systems using experimental study with crystalline nano cellulose-dispersed H2O/C2H6O2 nanofluids

This work examines the heat transfer properties of a forced convection circular tube heat exchange system employing a nanofluid made of crystalline nano cellulose (CNC) diluted in a 60:40 ratio of distilled water (H2O) and ethylene glycol (C2H6O2). The objective is to measure the generated nano-fluid's thermal characteristics and analyze its potential for usage as a cooling agent in thermal systems, with a focus on encouraging the use of this biodegradable green coolant. A single pipe forced convection system was used for the experimental experiments, which were focused on a temperature range of 30 °C to 100 °C and nanoparticle volume concentrations of 0.1% to 0.9%. The investigation looks at the density, heat conductivity, and viscosity of the nanofluid, among other important thermo-physical characteristics. The findings show that the coolant's density exhibits an inverse relationship with temperature, increasing as nanoparticle dispersion occurs. At a concentration of 0.9% and room temperature, the dynamic viscosity was 0.0096 kg m−1.sec. A 0.9% concentration of nanoparticle dispersion resulted in a significant increase in thermal conductivity of 27.8%. The effectiveness of the nanofluid is demonstrated by the measurement of pressure drop and convective heat transfer coefficients across the flow channel. The maximum convective heat transfer coefficient of 262.2 W m−2K−1 was recorded at a discharge rate of 17.5LPM and a concentration of 0.9% of nanoparticles. A temperature of 70 °C was found to yield the best heat transfer coefficient and the least amount of pressure loss when the nanoparticle volume percentage was 0.65%.

Thermal performance evaluation of an indigenously designed small-scale solar parabolic trough collector for manufacturing Indian milk products

ABSTRACT A small-scale solar parabolic trough collector system coupled with a jacketed vessel was designed and evaluated for its performance and quality of the products manufactured in it. The prototype having a 7.026 m2 aperture and 88.38° rim angle was installed in Mehsana, Gujarat, India. The study was conducted in May–June 2022 at different flow rates of sigma therm-k. The useful heat rate ranged from 567.82 W to 861.25 W. The daily average thermal efficiency was obtained in the range of 9.81–14.61% and maximum thermal efficiency achieved during the milk trials was 31.51%. Similarly, maximum absorber temperature achieved during stagnation was 193.4°C and during absorber fluid flow condition was 146.5°C. The maximum convective heat transfer coefficient of 49.5 W/m2K was calculated at Reynold number 1822 and Nusselt number 24.12. It was found that the quality parameters of manufactured milk products were at par with domestic food safety standards. Direct normal irradiance was found to be the most influencing factor followed by the initial milk load. The present system is a potential substitute for various small-scale Indian traditional heat-desiccated milk products, where higher thermal efficiency is not the primary requirement and emphasis is more on the importance of ease of operation.

Experimental and computational validation of thermal performance of an active greenhouse solar dryer in no-load conditions

Abstract This study focused on developing a finite element (FE) model using COMSOL Multiphysics to simulate the active mode of a greenhouse dryer under no-load conditions in Ranchi humid subtropical climate. The model visualized the temperature and humidity distribution within the dryer and was validated against real-world experimental results. Under unloaded conditions, the performance assessment revealed a 29.14% efficiency for the proposed dryer and a maximum overall convective heat transfer coefficient of 5.0 W/m2 °C. The internal temperature ranged from 50°C to 70°C, while the relative humidity hovered between 30% and 45%. The COMSOL Multiphysics-based FE model demonstrated close agreement between experimental and predicted results, with minimal statistical error. Overall, the findings suggest that the active mode of the greenhouse dryer could be a valuable tool for crop drying in humid subtropical climates. Additionally, the FE model presents a promising approach for future research and development.

Preparation and application of rice husk-based SiO2/water nanofluids in heat transfer enhancement under pulsation

Rice husk was used as raw-material to produce nano-SiO2 by the heat treatment method, and the structural characteristics of rice husk SiO2 (R-SiO2) was compared with the commercial SiO2 (C-SiO2) by various characterization methods. SiO2/water nanofluids were prepared by a two-step dispersion method using various sources SiO2 (R-SiO2 and C-SiO2) and applied in the convective heat transfer of corrugated tube channels in a self-built experimental platform. The experimental results showed that the specific surface area of the rice husk-based silica was high, reaching 335 m2/g. For the same nanofluids concentration, the thermal conductivity enhancement rate of R-SiO2/water nanofluid was higher than that of C-SiO2/water and the enhancement rate of 0.5% R-SiO2/water at 25 and 40 °C reached 14.01% and 12.16%, respectively. The convective heat transfer coefficient of R-SiO2/water was slightly better than that of commercial C-SiO2/water, which indicated that R-SiO2 has great potential to be a substitute of C-SiO2 for application in heat exchangers. The convective heat transfer characteristics of R-SiO2/water nanofluids in corrugated tube at different Re and volume concentrations were compared. It was found Nu augmented as Re increased. And a higher nanofluids concentration might result in a drastic increment in convective heat transfer coefficient. When a pulsating wave was imposed, the larger pulsation amplitude resulted in a higher heat transfer enhancement rate. And the enhancement rate at lower Re was better. Under the conditions of Re = 385, f = 0.67 and A = A15, the maximum average convective heat transfer enhancement rate reached 143%.

Application of Taguchi method and response surface methodology (RSM) for parametric optimization of natural convection heat transfer inside a triangular porous enclosure with in-line rectangular finned array

ABSTRACT Taguchi method is an experimental design methodology that uses a statistical technique to optimize process parameters while minimizing variability and improving output quality. In this article, Taguchi methodology has been utilized for parametric optimization of the design of a porous triangular enclosure, with an in-line rectangular finned array, to achieve maximum natural convection heat transfer. Three influencing parameters viz. fin spacing (S), percentage volume occupied (Vo) (measure of enclosure porosity), and fin tip to cooling plate distance (d), are optimized with consideration of maximizing the heat transfer (i.e. Nusselt number). The experimental design has been created using Taguchi’s L9 (3^3) orthogonal array. An analysis of variance (ANOVA) table, regression equation, response surfaces, and contour plots have also been generated using Response surface methodology, and the optimum values of influencing parameters have been suggested.

Performance assessment of a parabolic trough solar collector using nanofluid and water based on direct absorption

In this investigation, a parabolic trough solar concentrating collector with an evacuated tube was fabricated with an aperture area, collector length, breadth, and rim angle, inner and outer diameter of absorber as 2.45 m2, 2.1 m, 1.2 m, 90 deg, 0.0286 m, and 0.03058 m, respectively. A copper oxide (CuO) and water-based nanofluid was employed as the working fluid. Different mass fractions (0.05%, 0.075%, and 0.1%) and volume flow rates (70 lit/hr and 140 lit/hr) of nanofluid were taken, and performance of an evacuated tube parabolic trough collector was analysed. When CuO–H2O nanofluid of varying concentrations (0.05%, 0.075%, and 0.1%) is used in place of H2O (DI), it has been observed that the solar collector's efficiency increases. The efficiency of the collector increases in direct proportion to the working fluid's volume flow rate increment. The maximum heat transfer coefficients for CuO–H2O based nanofluid were 280.68 W/m2-K and 466.8 W/m2-K while the maximum convective heat transfer coefficients for water as working fluid were 268.11 W/m2-K and 488.7 W/m2-K at 70 lit/h and 140 lit/h, respectively. An efficiency increase of 45.15%, 51.19% and 53.26% for 70 lit/h and 59.61%, 63.56% and 69.07% for 140 lit/h mass flow rate has been observed for different nanoparticle's concentrations, respectively. Economic studies showed that the cost of the experiment (for 0.05% CuO dispersion) has increased by 1.08% for 70 lit/h mass flow rate when compared to the water based direct cooling method.

Effect of triangular porous layer on the transfer of heat and species in a channel‐open cavity

AbstractThis paper addresses the heat and species transfer in a composite cavity linked with a horizontal channel. The cavity comprises a triangular porous layer and one of its vertical sides is exposed to a high temperature and concentration. The mathematical conservation equations are solved numerically using the Galerkin finite element method. The ranges of Reynolds and Richardson numbers are taken to ascertain laminar flow, Re = 50–250 and Ri = 0.1–100. The size of the porous layer is quantified by the thickness of the porous layer Hp = 0.25–1. The problem is studied for two cases of heat and species sources; the opposing case, when the active side is on the right, and assisting case, when the active side is on the left. Results reveal that for specified conditions, the triangular porous layer increases Nusselt and Sherwood numbers by 30% and 32%, respectively, more than the horizontal porous layer. The opposing case gives maximum convective heat transfer, where for Ri = 0.01, the Nusselt number is higher by 61% and 134% for Re = 50 and 250, respectively, while for Ri = 100, the percentages increase are 67% and 43%.

Characterization of a Jet Impingement Heat Sink for Power Electronics Cooling

• Heat transfer correlations for a jet impingement heat sink for cooling power electronics are presented. • Pressure drop across the jet impingement heat sink investigated. • Heat transfer to pressure trade-off is critical for heat sink design. • Jet impingement provides good cooling uniformity. • Heat transfer is enhanced with decreasing stand-off distance and increasing jet-to-jet spacing. Ongoing demand to improve power electronic converters in terms of efficiency, power density, reliability, cost and packaging calls for optimal thermal management. This paper investigates the effectiveness of a jet impingement heat sink consisting of an array of jets impinging discrete heat sources. A mixture of 60 – 40% (by volume) ethylene glycol – water is the coolant used. Through computational simulations and experimentation on a laboratory prototype, the heat transfer and pressure drop of the heat sink is characterized in terms of Reynolds number, Prandtl number, stand-off distance and jet-to-jet spacing. Correlations for area averaged Nusselt numbers and the Euler number are presented. A trade-off between heat transfer and pressure drop performance is further studied. Higher heat transfer rates were obtained with smaller stand-off distances and larger jet-to-jet spacings at the cost of higher pressure drop. Over the range of parameters tested, heat transfer was found to be more sensitive to design changes (maximum variation of 17.3%) compared to pressure drop (<1% variation). An optimal design will consist of a low stand-off distance as this will provide maximum convective heat transfer rates at the cost of minor pressure drop increases and will ensure the heat sink is compact.

Energy and Exergy Analysis for Single Slope Passive Solar Still with Different Water Depth Located in Baghdad Center

In the present experimental work, the energy and exergy for single slope passive solar still with different basin water depths are experimentally investigated under the Baghdad climate condition. The analysis is performed using the governing equations formulated according to the first and second laws of thermodynamics. Compared to solar still with 1 cm water depth, the obtained results indicated that raising the water depth to 2 and 3 cm caused an appreciable drop in water basin temperature, and high levels of water basin reduction were about 4% and 9%, respectively, from 8:00 a.m. to 14:00 p.m., which significantly affects heat and mass transfer and ultimately hinders further water productivity. The maximum evaporation and convection heat transfer coefficients are found (32 W/m2·k) and (2.62 W/m2·k), respectively, while the maximum productivity of solar still is found to be 1468.84 mL/m2 with 1 cm water depth. Conversely, stills with 2 and 3 cm water depth, exhibit an increment of the daily exergy efficiency after 14:00 p.m., this increment was the most for the still with 3 cm water depth. Therefore, we have concluded that the still with 1 cm of water depth attained the highest water productivity, while the still with 3 cm of water depth attained the best exergy efficiency with no additional costs.

Effects of flow and heat transfer around a hand-shaped former

Rubber glove manufacturing requires improvements in the curing process. In this study, the forced convection of hot airflow past a hand-shaped former, which has a typical shape in the rubber glove manufacturing process, was examined. A former model consisting of five fingers, palm, dorsum, and wrist was separated to investigate the convective heat transfer of the individual parts by OpenFOAM. The study conditions for the manufacturing process were a Reynolds number ranging from 15,837 to 63,351 and an angle of attack from 0° to 180°. After validating the computational fluid dynamics models with experiments and previous research, the k–ω shear stress transport turbulence model was appropriate. The angle of attack slightly affected the average Nusselt number on all parts of the hand-shaped former except the dorsum. An optimization method was employed to determine the optimal attack angle that caused the maximum convective heat transfer. The result was 0°. Therefore, the simulation results for the dorsal part at 0° established an average Nusselt number equation. This equation had an accuracy with an average error of less than 0.24% and an R 2 of 0.9997. The average Nusselt number equation of the dorsal part is representative for analyzing the heat transfer in the curing process in rubber glove manufacturing.

Review on aqueous graphene nanoplatelet Nanofluids: Preparation, Stability, thermophysical Properties, and applications in heat exchangers and solar thermal collectors

Nanofluids of graphene nanoplatelets (GNP) have superior thermal performance characteristics and good stability, are relatively affordable, and can easily be prepared by the two-step method. This review performs an in-depth analysis of the preparation, stability, and thermophysical properties of GNP nanofluids, and their applications in heat exchangers, solar thermal collectors, and heat pipes. This study analyses in detail the performance improvements achieved with pristine, covalent functionalised, and non-covalent functionalised GNP nanofluids compared to water. Covalent functionalisation was found to be superior to non-covalent functionalisation in terms of stability and heat transfer coefficients. Functionalisation by electrophilic addition and free-radical grafting were found to be more environmentally friendly compared to acid treatment. In terms of convective heat transfer coefficient, pristine GNP outperformed functionalised GNP, but both types showed large improvements compared to water. It was found that stability and heat transfer performance improved as particle size was decreased, while thermal conduction and convection coefficients increased with nanofluid concentration and temperature. Thermal conductivity improvements of over 30% were found for both pristine and covalently functionalised GNP nanofluids at 0.1 wt% concentration. A maximum convection heat transfer coefficient increase of 200% was achieved using 0.1 wt% pristine GNP nanofluid. By comparison, a maximum improvement of 119% was achieved using covalently functionalised GNP. The convective heat transfer enhancement seemed to increase with decreasing tube diameter. In flat plate solar collector applications, efficiency improvements over 20% were obtained for covalently functionalised GNP nanofluids at 0.1 wt%, while an efficiency improvement of over 65% was obtained using pristine GNP in an evacuated tube solar collector. Applications in cooling, heat pipes, and direct absorption solar collectors were also reviewed. From this study, it could be inferred that GNP nanofluids are a viable alternative working fluid. Further research is needed to optimise their performance.

Impact of hybrid nanofluids (Ag‐TiO2/H2O) on improving the performance of a heat exchanger with turbulent induction elements

AbstractIn this article, the optimization of a twisted strip heat exchanger was explored aiming at enhancing heat transfer. To this end, governing equations using ANSYS‐FLUENT software and nanofluid flow using the k‐ε RNG turbulence model were simulated in the heat exchanger, respectively. The investigated parameters included temperature, pressure, velocity, turbulence kinetic energy (TKE), nanofluid concentration, nanofluid shape factor, Reynolds number, and the diameter of the spherical obstacle on the twisted tape. In addition, the applied nanoparticles were Ag and TiO2, which were combined as a hybrid with a ratio of 50%–50%. Investigations on the surface of the twisted tape with a spherical obstacle revealed a reduction in the temperature while an increase in pressure changes, velocity, and TKE. Moreover, it was specified that the application of lamina‐shaped (non‐spherical) nanofluid has the maximum convection heat transfer coefficient relative to platelets and spherical shapes. The highest heat transfer rate was achieved at a nanofluid concentration of . Based on the findings, the heat transfer rate upgraded by increasing the Reynolds number such that the highest heat transfer rate was gained at Reynolds number 18,000. Finally, the heat transfer coefficient was enhanced by approximately 52% by increasing the diameter of the obstacles from 3 to 12 mm.

Optimization of Parameters Affecting Anti-Icing Performance on Wing Leading Edge of Aircraft

In this article, one of the hazardous trouble in-flight situations called ice accumulation on wing leading edge of aircraft has been numerically investigated. While the target surface is kept constant temperature at Tw=263.15 K, the inlet temperature is taken constant at Tin=473.15 K and it enters to the system with m ̇=0.004 kg/s. The investigation starts with validation of numerical study utilizing airfoil type of NACA 0015 using constant piccolo tube dimensions, jet angle, distance among jets and distance between jet-to-target positions. The second and third stages are to analyze the anti-icing performance of changing positions of piccolo tube on X (4≤H/d≤8) and Y (-1.25≤L/d≤1.25) directions under different jet angles (30°≤≤150°). The fourth stage is to determine the optimum H/d, L/d, and ratios to increase anti-icing performance with maximum convective heat transfer and minimum pressure drop condition. The optimization study has been done using Response Surface Methodology (RSM). Finally, while the best anti-icing performance proposed design is achieved using° L/d=0.0, and H/d=4.0, the optimization results show that the L/d, and H/d values should be 55.45°, 0.0, and 4.0, respectively to achieve maximum heat transfer rate with minimum pressure drop value.

Effect study of super-critical CO2 parameters on heat transfer performance of U-shaped double-pipe heat exchanger

This paper presents a numerical study on the heat transfer performance of U-shaped double-pipe heat exchanger for the concentrated solar power system. The effects of the mass flow rate, temperature and pressure of inlet super-critical CO2 are evaluated. The results show that due to the effect of centrifugal force, temperature and flow velocity distribution divergences happen in the elbow part of the double-pipe. That can enhance the heat transfer performance. With the inlet super-critical CO2 mass flow rate increased, the convection heat transfer coefficient and Nusselt number of the super-critical CO2 both increase. When the inlet super-critical CO2 mass flow rate increases to 0.6 kg s−1, the maximum local average convection heat transfer coefficient and Nusselt number of the super-critical CO2 are 7120.0 W m−2K−1 and 1892.7. By increasing the inlet super-critical CO2 temperature or pressure, the convection heat transfer coefficient of the S–CO2 can be increased. With the inlet super-critical CO2 temperature increased from 700.0 K to 780.0 K, the maximum local average convection heat transfer coefficient of super-critical CO2 increases from 5034.5 W m−2K−1 to 5149.1 W m−2K−1. Compared with the other two parameters, the effect of inlet super-critical CO2 pressure on the heat transfer performance is relatively smaller.

Experimental analysis of solar air heater using polygonal ribs in absorber plate integrated with phase change material

Heat transfer enhancement in solar air heater has been investigated by implementing rough surfaces in the absorber plate. We use paraffin wax is used as phase change material integrated with solar air heater as a thermal energy storage system. A maximum convective heat transfer is attained during the daytime and retained as latent heat to discharge heat during OFF radiation. In this investigation, two types of absorber plates were employed such as flat and polygonal-shaped ribs at the test section. Further to investigate the heat transfer enhancement, the research was conducted with and without phase change material. The study was carried out at the mass-flow rates of 0.062 kg/s, 0.028 kg/s, and 0.01 kg/s to ascertain the enhancement of thermal efficiency and heat discharge duration. The temperatures of absorber plate, Tp, ambient Tamb, outlet, Tout, and phase change material along with solar intensity, I [Wm?2], were taken as the main parameters. The research reveals that the absorber plate with polygonal ribs tested with phase change material yields a higher temperature of 77?C with a mass-flow rate of 0.062 kg/s during peak radiation. Discharged heat energy from phase change material to absorber plate for 3.5 hours with a maximum temperature of 7.1?C.

Effect of Pitch Ratio and Diagonal Length of Pin Fin of Heat Sink on Convective Heat Transfer for Turbulent Flow Condition

In this study, the impact of pitch ratio and diagonal length of pin fin on the heat sink has been numerically investigated to determine the thermo-hydraulic performance of heat sink under turbulent flow regime. Usage of pin fin on the heat sink has been preferred due to less pressure drop in comparison with general fin type. While the pitch ratio has been changed 0.75 ≤ P/e ≤ 1.1, the length of edge of fin has been changed 3 ≤ Lef ≤ 6 as geometric parameters. The working range of the study has been considered as turbulent flow regime (2658 ≤ Re ≤ 7138). The computational study has been carried out on ANSYS Fluent 2020R2 using SST k-ω with low-Re correction model to calculate RANS equations. The factors, which define thermo-hydraulic performance of the study, such as average Nusselt number, average Darcy friction factor, and thermal resistance has been elucidated in detail. Also, to detect flow characteristics comprehensively, the contours have been created for vorticity, temperature, and velocity streamline. As a results of overall assessment of this study, it is concluded that the maximum convective heat transfer performance has been obtained using Case 12 by 52% compared with the Case 1 at Re=7138.

Thermo-magnetic convection of nanofluid in a triangular cavity with a heated inverted triangular object

The present study aims to explore the buoyancy-driven convective phenomena of nanofluid flow in a cavity of an isosceles triangle with an inverted triangular heat source under the effect of a sloped magnetic field. The cases of different heating loads are analyzed considering various sizes of the heating triangle. The outer triangular cavity is kept at a lower temperature; whereas the inner inverted triangular is maintained as the isothermal heat source. Space in-between the inner and other triangle is filled with nanofluid (Al2O3-water). Finite element methodology is adapted to compute the coupled transport equations numerically. The convective phenomena and associated heat transfer characteristics are examined systematically for a range of control parameters like Rayleigh numbers (103–106), Hartmann number (0–70), and magnetic field inclination angle (0−180°), and the size of the inner inverted triangular heat source. The illustrations of local distribution of streamlines, isotherms, entropy generation are presented along with the average Nusselt number, Nu. It shows that the size of the inner triangular heat source controls the overall thermal behavior. The maximum convective heat transfer is obtained with the least flow obstruction (i.e. smaller size of the inner triangle). The study of magnetic field inclination shows that maximum heat transfer is obtained at an inclination of 90° and minimum flow obstruction.

Effect of Magnetic Field on the Forced Convective Heat Transfer of Water–Ethylene Glycol-Based Fe3O4 and Fe3O4–MWCNT Nanofluids

This paper discusses the forced convective heat transfer characteristics of water–ethylene glycol (EG)-based Fe3O4 nanofluid and Fe3O4–MWCNT hybrid nanofluid under the effect of a magnetic field. The results indicated that the convective heat transfer coefficient of magnetic nanofluids increased with an increase in the strength of the magnetic field. When the magnetic field strength was varied from 0 to 750 G, the maximum convective heat transfer coefficients were observed for the 0.2 wt% Fe3O4 and 0.1 wt% Fe3O4–MWNCT nanofluids, and the improvements were approximately 2.78% and 3.23%, respectively. The average pressure drops for 0.2 wt% Fe3O4 and 0.2 wt% Fe3O4–MWNCT nanofluids increased by about 4.73% and 5.23%, respectively. Owing to the extensive aggregation of nanoparticles by the external magnetic field, the heat transfer coefficient of the 0.1 wt% Fe3O4–MWNCT hybrid nanofluid was 5% higher than that of the 0.2 wt% Fe3O4 nanofluid. Therefore, the convective heat transfer can be enhanced by the dispersion stability of the nanoparticles and optimization of the magnetic field strength.

Experimental investigation on thermosyphon aid phase change material heat exchanger for electronic cooling applications

In this work, cooling of electronic modules is experimentally investigated using a thermosyphon aid phase change material (PCM) heat exchanger with different thermic fluids such as n-hexane, benzene and DI water respectively. The experiments are conducted simultaneously by evaluating the thermal performance of thermic fluids and heat power stored by PCM for various heat inputs ranging from 70 to 110 W. At high heat input conditions, the value of low thermal resistance, maximum convective heat transfer coefficient (CHTC) and percentage of heat extraction of n-hexane are 0.350 K/W, 185.53 W/m2K and 99.2% respectively. Low enthalpy of vapourization and a high degree of superheat is the criteria for the obtained results. Also, temperature variation in PCM during melting is analysed by the influence of vapourized thermic fluids for different heat inputs. The maximum heat power stored by PCM is found as 7.78 W for vapourized n-hexane at 110 W due to high mass flow rate and less time for reaching steady-state temperature (SST) of PCM. The solidification of PCM is noted using cold water at regular time intervals during power-off conditions and observed that n-hexane influenced molten PCM takes 25 min for complete solidification.

Analysis of convection heat transfer on multiscale rough superhydrophobic and liquid infused surfaces

Multiscale rough superhydrophobic or slippery liquid infused porous surfaces have gained much interest in recent years for their improved transport phenomena properties. While there have been several studies on drag reduction and condensation on non-wetting surfaces, convection heat transfer that is important in many thermal and thermochemical applications has not been addressed systematically. This article utilizes a fractal description of rough surface topographies to develop analytical models for the Nusselt number and the thermal hydraulic factor for fluid flow and heat transfer inside a cylinder with non-wetting surfaces. For air-infused superhydrophobic surfaces, the model considers the dynamic stability of the air/fluid interface in the asperities. Using the analytical formulations and the stability criteria, systematic studies are presented on the effects of the fractal surface parameters, cylinder radius and Reynolds number on the convective heat transfer characteristics, from which surface texture design maps are developed for maximizing the convection heat transfer. It is shown that multiscale non-wetting surfaces are most effective in the range of lower Reynolds number and small cylinder radius for achieving the best convective heat transfer and thermal hydraulic performance. Applying the models to actual non-wetting surface topographies fabricated using electrodeposition and chemical etching, it is shown that contrary to prevailing notion, superhydrophobicity, characterized by the highest contact angles, does not always lead to the maximum convective heat transfer performance, and that under certain fluid flow conditions, hydrophobic surfaces may offer a greater thermal performance.