Local Convective Heat Transfer Research Articles

Target temperature-based simulation method for predicting performance and designing aircraft thermal anti-icing systems

The prevention of ice build-up on aircraft surfaces is crucial for safe operations. Thermal ice protection systems, particularly electro-thermal systems, are commonly employed to mitigate ice formation. However, the weight of electric batteries used in these systems significantly impacts aircraft performance, necessitating the minimization of power load during design. Despite this requirement, effective anti-icing operation mandates a sufficient heat flux to maintain surface temperature above the freezing point and evaporate any runback water film. Previous research has utilized numerical simulation analysis to predict the performance of electro-thermal anti-icing systems. The conjugate heat transfer method has been commonly employed to predict temperature distribution on the protected surface. However, non-isothermal surfaces exhibit distinct local convective heat transfer coefficients that influence local thermal balance, unlike isothermal surfaces that adopt the loosely-coupled method for computational efficiency. In this study, we present a novel target temperature-based anti-icing simulation method that predicts the required heat flux for thermal ice protection systems without employing the conjugate heat transfer method. Our objective was to calculate the necessary heat flux to achieve the desired non-isothermal surface temperature for effective anti-icing. By eliminating the excessive iteration process associated with the coupling method for conjugate heat transfer, we have streamlined the simulation procedure. Through validation, target temperature-based anti-icing simulation method, when compared to the tight coupling method, demonstrated the ability to predict the same surface water flow rates while reducing computation time by up to 90 %. Furthermore, when applied to design problems, our method achieved approximately a 10 % reduction in the required heat capacity for anti-icing compared to experimental values. As a result, target temperature-based anti-icing simulation method offers a more efficient alternative to traditional conjugate heat transfer methods, providing valuable insights for both predicting anti-icing system performance and optimizing aircraft design.

Evolution of flow structure and heat transfer enhancement mechanism in impinging jets excited by piezoelectric fan

While jet impingement is recognized for significantly enhancing local convective heat transfer, there remains a considerable challenge in further improving its heat transfer performance and uniformity to meet the growing demand for efficient heat transfer. To address this challenge, this study proposes a method that integrates a piezoelectric fan into a continuous jet, taking advantage of the piezoelectric fan's vibration to deliver pulsating excitation to jet impingement while preserving its continuity. An experimental study is performed to identify the roles of piezo-fan integration on improving convective heat transfer from a continuous circular jet onto a flat target surface. The tests are performed under Rej=2,500∼7,500 (circular jet), s/d = 2∼28 (non-dimensional fan-to-jet distance) and L/d = 2∼8 (non-dimensional jet-to-target distance). In addition, few numerical simulations regarding the flow fields are also made to illustrate the mutual interaction mechanism between piezo-fan and continuous jet. The findings reveal that, in the longitudinal configuration, the average values of heat transfer enhancement factor (χ) and heat transfer uniformity factor (ξ) are approximately 13% and 0.5% higher, respectively, compared to the transverse configuration. In the longitudinal arrangement, the significance of the piezoelectric fan amplifies as the circular nozzle gradually distances itself from the target surface. This fan assumes a pivotal role in augmenting both the uniformity and efficiency of heat transfer associated with the circular jet. Conversely, when the piezoelectric fan moves beyond a specific s/d value (s/d = 10), the interaction between intermittent flow and the wall-jet experiences complete cessation. Despite the existence of a fountain effect resulting from the interaction between the piezoelectric fan and the circular jet in the longitudinal configuration, its discernible impact on overall heat transfer attenuation is minimal. The insights gained from this study will be valuable in improving active strategies for jet impingement and promoting the development of piezoelectric functional devices.

Convective heat transfer of falling film around the horizontal half-oval tube with reverse airflow in an evaporative condenser

Horizontal falling-film evaporation is frequently used in industrial air conditioning system to improve its thermal performance. Transient heat transfer characteristics on the surface of a circular tube have been investigated, while the non-circular tube such as half-oval tube has been rarely reported. This study aims to investigate the thermal performance of liquid film around a half-oval tube by adopting transient simulations with laminar and SST k-ω models, respectively. Simulations consider varying wind velocity, liquid Reynolds number, heat flux and length-width ratio of the tube. Simulated results are quantitively validated by comparing with reported experimental results, and the average differences are below 9.5 %. Results indicate that the local convective heat transfer coefficient (CHTC) increases with wind and the average CHTC is at least 5.98 % higher than the case without wind. Although the influences of liquid Reynolds number and heat flux show slight differences, they still can improve the convective heat transfer. The local CHTC exhibits an escalating trend with length-width ratio of 1–5. Meanwhile, the average CHTC for the four tested half-oval tubes is at least 6.8 % higher than the values of the circular tube. An empirical correlation for predicating the average CHTC is established by regression fitting with a mean deviation of 4.6 %. These findings help to design the falling-film evaporation system by adopting the half-oval tube in industrial air conditioning system.

Multi-tiered configurations improved flow boiling performance: Comparation investigation of leaf vein inspired two-tiered and three-tiered open microchannels

Microchannel heat sinks with expanding flow area along with the flow direction are able to suppress flow instability and reduce pressure drop during two-phase flow boiling by offering broadening volume for bubble elongation and growth that suppress the slug blockage and flow reversal. In this regard, microchannels with expanding area perpendicular to flow direction are supposed to obtain the comparable results, as the bubbles migrate to the downstream and top of microchannels simultaneously. However, the relevant study about multi-tiered microchannel heat sinks was limited and the corresponding flow boiling characteristics remained elusive. In this work, leaf vein inspired two-tiered open microchannel (LTWOMC) and three-tiered one (LTHOMC) were proposed and comparative flow boiling experiments were carried out. The outcomes indicated that LTWOMC obtained earlier ONB, which was 6.4 °C lower than LTHOMC at G = 220 kg/m2·s, the average local convective heat transfer coefficient (hcon) and average two-phase one (htp) of LTWOMC were maximumly enhanced up to 36.3% and 148.7% at G = 150 kg/m2·s, respectively. The pressure drop (ΔP) of LTWOMC was generally larger than LTHOMC at all mass fluxes, which led to the cooling coefficient of performances (COPs) of LTHOMC superior compared to LTWOMC under all working conditions. Moreover, LTHOMC exhibited better flow stability than LTWOMC with lower amplitudes and standard deviations of both wall temperature and pressure drop. In general, the three-tiered hierarchical configuration is more suitable than two-tiered one for flow boiling heat transfer.

Experimental investigation of the convective heat transfer coefficients at different angular orientations inside the void in a cold flow pebble bed reactor using a non-invasive heat transfer pebble probe

This study focuses on investigating the effect of the surface location of the pebble inside the bed, by varying the angular orientation of the heat transfer pebble probe and the velocity of the gas on the convective heat transfer coefficients in a cold-flow pebble bed reactor. An advanced non-invasive technique consisting of a cartridge heated copper pebble, a micro-foil sensor and a thermocouple probe was used to obtain accurate measurements of the local heat transfer coefficients from three surface locations inside the void. The effect of the wall on the local convective heat transfer coefficients was highlighted due to the low aspect ratio of the bed (bed diameter to pebble diameter (5cm)) used in this work. The local measurements showed, for the first time ever, that the surface location inside the void substantially impacts the heat transfer coefficients, with higher heat transfer coefficients at the center of the void and bottom of the void. Furthermore, the measured overall heat transfer coefficients showed good agreements with the predictions of the correlations of [52,21] and [14]. A second order polynomial model with an R2=0.9807 and an average absolute relative error (AARE) equal to 9.08%, was developed for the prediction of the local heat transfer coefficient within the design and operation conditions of this work. The accurate local heat transfer data collected in this work is valuable as benchmark data for the validation of computational fluid dynamics (CFD) simulations and heat transfer calculations.

Conjugate heat transfer of a turbulent tube flow of water and GaInSn with azimuthally inhomogeneous heat flux

An experimental study of the conjugate heat transfer in a turbulent tube flow with azimuthally homogeneous and inhomogeneous heat flux distribution, where the tube is heated with a constant heat flux only over the half circumference, is presented. Using two fluids with clearly different Prandtl numbers (water and a liquid metal alloy), thermohydraulic effects that occur when fluids with very low Prandtl number are used in contrast to ordinary fluids (e.g. water with Pr≈1) are discussed. The test section is validated with water (Pr=5−7.4) for a Reynolds number in the range of 5·103<Re<4.2·104. The experimental data agree excellently with literature data. The maximum nondimensional temperature at the inner surface of the tube is expressed using a simple relationship based on the efficiency of a fin with an adiabatic tip. A near eutectic alloy of gallium, indium and tin (GaInSn, Pr=0.03) is used for the liquid metal experiments. The Péclet number is varied within the range of 240<Pe<3·103. Based on the experimental data of this work, an adapted correlation for the Nusselt number in a turbulent liquid metal tube flow with azimuthally homogeneous heat flux is provided:Nu=4.364+0.0276·Pe0.803The experimental data underlines, that the azimuthally averaged Nusselt number for an azimuthally inhomogeneous heat flux distribution can also be calculated with this correlation with an acceptable level of accuracy. Remarkably, the ratio of the local convective heat transfer coefficient to the azimuthally averaged value for GaInSn reaches a value up to 0.6 at the location of the maximum wall temperature. This is in strong contrast to water, where this ratio is close to unity.

A general approach for predicting convective heat transfer coefficients in turbulent systems

A generalized approach for predicting turbulent convective heat transfer coefficients using large eddy simulation is presented. This model is based on semi-empirical transport theory, which links the local convective heat transfer rate to the local energy dissipation rate within the near-wall boundary layer. We apply these approaches to agitated tanks, pipe flow systems, cylinders in crossflow, and tube bundles. We validate the generality and reliability of the theoretical model against expectations from experimentally derived empirical design correlations.

Experimental Study of the Corrugation Profile Effect on the Local Heat Transfer Coefficient

This paper introduces an inverse study method applied to an experimental dataset of infrared temperature acquisitions to determine the local convective heat transfer coefficient of the turbulent flow inside a duct with corrugated surfaces. The study focuses on six tubes with different corrugation profiles: helical, transversal, and cross-helical. Previous research has shown that transversal corrugation generates the highest improvement in heat transfer performance, while helical corrugations are the easiest to manufacture. Consequently, the single helix solution is the preferred one in heat exchangers adopted in the food industry. A merger solution between them is represented by the cross-helix profile. The estimation process proposed in this study employs the external surface temperature of the tube, acquired with an infrared thermal camera, as starting data for the inverse heat conduction problem inside the pipe wall region. The calculation of its Laplacian was finally achieved by a filtering technique applied to the infrared temperature acquisitions.

Experimental investigation on heat transfer of nitrogen flowing in a circular tube

Average and local convective heat transfer coefficients of nitrogen are measured experimentally in an electrically heated circular tube for a range of Reynolds number from 1.08 × 104 to 3.60 × 104, and wall-to-bulk temperature ratio from 1.01 to 1.77. The exit Mach number is up to 0.17, and the heat flux is up to 46 kW·m−2. The molybdenum test section has a 62 diameters heated section with an inside diameter of 5 mm and a 30 diameters entrance section to ensure the fully-developed flow. Uncertainty of Nusselt number is less than 1.6 % in this study. The results indicate that the average heat transfer correlations evaluated by both the bulk and the modified film Reynolds numbers agree well with the experimental data. The local heat transfer results based on bulk properties are compared with previous empirical correlations. New prediction correlations are recommended which are significantly affected by the property variation and heated length. The comparison between the proposed correlations and experimental points shows that 88 % of experimental data fall into an error of 10 %, and almost all data are within an error of 20 %.

Investigating the impact of modeling assumptions and closure models on the steady-state prediction of solar-driven methane steam reforming in a porous reactor

In this work, the effect of different modeling assumptions and closure models — frequently considered in the literature of solar thermochemical reactors and closely-related areas — is investigated. The application of different modeling assumptions and closure models may strongly affect the results accuracy and compromise a meaningful comparison across literature works. The following is herein investigated: (i) the role of upstream and downstream fluid regions to the two-phase reactor region; (ii) relevance of species and gas-phase thermal diffusion mechanisms; (iii) reaction heat accounted for in gas- or solid-phase energy balance equations; (iv) local thermal equilibrium (LTE) vs. local thermal non-equilibrium (LTNE) models; (v) model dimension (one-dimensional vs. two-dimensional axisymmetric models); (vi) local volumetric convection heat transfer correlations; and (vii) effective solid thermal conductivity correlations. The relevance of this work extends well beyond the current application (methane steam reforming in a volumetric solar reactor), since similar models and assumptions have also been widely applied for predicting the performance of volumetric solar absorbers and dry reforming solar reactors. The results show that an upstream fluid region should be considered while applying inlet first-type boundary conditions and diffusion transport in the corresponding governing equations to ensure full-conservation and simultaneously to account for developing profiles upstream the reactor inlet section. For the operating conditions considered, species diffusion and gas-phase heat conduction are particularly relevant at the reactor centerline but with a negligible integral effect. A significant difference in the reactor performance is observed while accounting for the reaction heat from surface reactions in the solid- or gas-phase energy balances — for the lowest inlet gas velocity herein considered, the thermochemical efficiency (methane conversion) is approximately equal to 70.8% (76.3%) and 77.3% (84.7%) assigning the reaction heat to the gas- and solid-phase energy balances, respectively. LTE model results are strikingly different from the results obtained with the LTNE model considering the reaction heat accounted for in the gas-phase energy balance but not significantly different from the results computed with the LTNE model with the reaction heat assigned to the solid-phase energy balance. One-dimensional reactor modeling provided with an average concentrated solar heat flux value results in a similar average performance as that given by a two-dimensional model but fails to predict the high temperatures observed at reactor centerline — for the lowest inlet gas velocity, the difference between the maximum solid temperatures predicted by one- and two-dimensional models is about 340K.

Micro segment analysis of supercritical methane thermal-hydraulic performance and pseudo-boiling in a PCHE straight channel

The printed circuit heat exchanger (PCHE) is receiving wide attention as a new kind of compact heat exchanger and is considered as a promising vaporizer in the LNG process. In this paper, a PCHE straight channel in the length of 500 mm is established, with a semicircular cross section in a diameter of 1.2 mm. Numerical simulation is employed to investigate the flow and heat transfer performance of supercritical methane in the channel. The pseudo-boiling theory is adopted and the liquid-like, two-phase-like, and vapor-like regimes are divided for supercritical methane to analyze the heat transfer and flow features. The results are presented in micro segment to show the local convective heat transfer coefficient and pressure drop. It shows that the convective heat transfer coefficient in segments along the channel has a significant peak feature near the pseudo-critical point and a heat transfer deterioration when the average fluid temperature in the segment is higher than the pseudo-critical point. The reason is explained with the generation of vapor-like film near the channel wall that the peak feature related to a nucleate-boiling-like state and heat transfer deterioration related to a film-boiling-like state. The effects of parameters, including mass flow rate, pressure, and wall heat flux on flow and heat transfer were analyzed. In calculating of the averaged heat transfer coefficient of the whole channel, the traditional method shows significant deviation and the micro segment weighted average method is adopted. The pressure drop can mainly be affected by the mass flux and pressure and little affected by the wall heat flux. The peak of the convective heat transfer coefficient can only form at high mass flux, low wall heat flux, and near critical pressure, in which condition the nucleate-boiling-like state is easier to appear. Moreover, heat transfer deterioration will always appear, since the supercritical flow will finally develop into a film-boiling-like state. So heat transfer deterioration should be taken seriously in the design and safe operation of vaporizer PCHE. The study of this work clarified the local heat transfer and flow feature of supercritical methane in microchannel and contributed to the deep understanding of supercritical methane flow of the vaporization process in PCHE.

A reduced-order electrochemical model for analyzing temperature distributions in a tubular solid oxide fuel cell stack

It is challenging to improve the computational efficiency of temperature predictions in tubular solid oxide fuel cell (SOFC) stacks, since the complex flow field usually leads to non-uniform heat generations and heat dissipations. In this study, we have developed a reduced-order electrochemical model for fast predicting the temperature distributions in a kilowatt-class tubular solid oxide fuel cell stack. This model can explicitly express the current density as a function of operating potential, concentration, and temperature, which can significantly reduce the computational cost of stack level simulations. The influence of flow characteristics on temperature distributions in the tubular SOFC stack is examined and analyzed. We show that the vortices formed by flow separations could affect temperature uniformity among all cells. At a low inlet air velocity, few vortices are formed, and the convective heat transfer is too weak to dissipate the heat generations from electrochemical reactions. As the air velocity is increased, the number and strength of vortices are both increased. These vortices enable the air stream to flow spirally and enhance the local convective heat transfer. We also demonstrate that as the air inlet velocity is increased from 1 m/s to 4 m/s, the temperature uniformity among tubular solid oxide fuel cells first decreases and then increases, but the output power is reduced from 2.19 kW to 1.78 kW due to the decrease in operating temperatures. The inlet air velocity should be carefully selected to balance the electrical and thermal performance of the SOFC stack.

A fractal blade for cooling liquids: Experiments and simulations

The performance of a fractal geometry blade for cooling hot water by natural convection and evaporation was studied numerically and experimentally. The blade design includes a tree-like fractal pattern and the Sierpinski carpet. The fin is made up of a solid hollow structure whose core is embedded with a porous material through which liquid flows. For the experiments, temperature measurements were taken in the porous medium by holding the fin in a fixed vertical position while warmed water was fed through its flow inlet. Numerical simulations were performed using a two iteration scheme that first involves the calculation of the local convective heat transfer coefficients and then the estimation of the heat dissipated by evaporation. The behavior of the fractal blade was compared with that of a benchmark heat sink that does not include the Sierpinski pattern in its construction. The experimental and numerical results agree well with each other and show a better performance of the reference heat sink when cooling water. Although the windows in the Sierpinski pattern improve convective cooling, this effect is marginal compared to evaporative cooling, which is enhanced by the larger surface area of wet porous medium exposed to the environment in the benchmark fin.

Effect of thin-film sensors on local heat transfer in convective heat flux measurement

Thin-film heat flux sensors are usually attached to the interesting surface for the measurement of wall heat flux in the aerospace industry. However, the presence of the surface-mounted sensors may disturb the velocity and thermal boundary layer, alert the local wall heat flux, and induce erroneous measured results. This study numerically investigates the effect of the presence of thin-film heat flux sensors on the local flow and heat transfer. The effects of both Reynold number of the flow and the geometry of the sensor are investigated. The results show that the local convective heat transfer can be remarkably enhanced by the presence of the sensor. In particular, when the height of the thin-film heat flux sensor is within 2% of the flow boundary layer, the enhancement of the convection heat transfer caused by the heat flux sensor is independent with the inlet velocity of the flow. Finally, an empirical model for estimating the influence of the sensor on the heat transfer is established based on the numerical findings, which can provide a useful tool for practical design to evaluate and minimize the effect of the sensor on the local convective heat transfer.

Flow and heat transfer in rotating smooth and ribbed multi-channel double-wall structure with multiple-jet impingement cooling

In this study, the heat transfer of multiple-jet impingement in rotating smooth and ribbed multichannel double-wall cooling structure with film extraction are investigated. The dimensionless jet-to-target spacing is 1, and the dimensionless jet-to-jet spacing is 3.55. In ribbed channel, the rib height is 1 mm and rib spacing is 8 mm. The experimental jet Reynolds number ranges from 2000 to 8000, and the maximum jet rotation number is 0.22. The test section contains five impingement channels. The local average convective heat transfer coefficient is measured by the “copper plate method”. The SST k-ω model is used to study the effect of rotation on the flow in channels. The results show that the heat transfer gap between high and low radius is more evident with an increase of the Roj. This is because the rotation effect increases and decreases the mass flow rate at high and low radius, respectively. Moreover, rotation can strengthen the impingement effect of the trailing side (TS) while weakening the effect of the leading side (LS) when the Roj is less than 0.06, Which causes differences in the heat transfer between the LS and TS of the impingement channel. Furthermore, affected by the ribs, the average heat transfer of ribbed target surface is improved. The area of high heat transfer region generated by impingement decreases, and an inverted butterfly-shaped high heat transfer region is generated near the film hole. Finally, the rib weakens the effect of rotation on the flow of target surface to some extent.

Case studies on local mixed convection heat transfer coefficients along a radiant heated wall subjected to displacement ventilation

Case studies on local mixed convection heat transfer coefficients along a radiant heated wall subjected to displacement ventilation

Pore-scale numerical simulation and LTNE analysis for fully-developed forced convective heat transfer in packed beds of mono-sized rough spheres covering near-wall and core regions

This work presents a novel method to acquire the effective convection heat transfer coefficients on the interfaces of wall-fluid contacts and sphere-fluid in both the near-wall region and core region of sphere-packed beds. Pore-scale numerical simulations are first conducted for different porosities pertaining to two regular body-centered cubic and face-centered cubic packings, packing lattice angles, inflow velocities, and ratios of the thermal conductivities of the solid and fluid. A finite-thickness metal reactor wall is included in the pore-scale simulation to make the heating boundary conditions more realistic. The outer surface of the metal wall is subjected to a uniform heat flux. The heat then passes through the metal wall and dispenses into the solid and liquid phases of the packed bed through the wall-sphere and the wall-fluid interfaces at the inner wall according to the physical mechanisms. Within the reactor, the heat transfer mechanism is separately considered in the near-wall region and the core region due to the intrinsic differences in the flow pattern. For each packing, different inflow angles are examined and exhibit different flow patterns and heat transfer performances. After the whole domain is hydrodynamically and thermally fully-developed, the local effective convection heat transfer coefficients can then be calculated. These coefficients reflect the realistic local convection either on the reactor wall or on the sphere-fluid interface. These convection heat transfer coefficients, along with the effective solid thermal conductivity through the contacting spheres obtained in our previous work, are implanted into a modified two-equation LTNE model. This modified LTNE model yields linear longitudinal fully-developed temperature distributions within the reactor having discrepancies in the temperature slopes less than ±10% from those by the pore-scale numerical simulations. In contrast, the conventional model even fails to reach linear distributions of the solid- and liquid-phase temperatures, which are expected for fully-developed packed-bed flows.

Experiment on liquid film flow and heat transfer of laminar liquid jet impacting on cylindrical surface

Laminar liquid jet impact has good heat transfer performance with low impact stress on targets. In order to explore the liquid film flow and heat transfer under laminar liquid jet impact on a cylindrical surface, first the flow of a liquid film was analyzed visually; then, the local convective heat transfer characteristics on the cylindrical surface at different impact heights and outlet Reynolds numbers (Re) were obtained by a combination of direct measurement and numerical simulation, followed by a comparative analysis with continuous droplets impacting on the cylindrical surface. The results show that according to flow behavior of the liquid film along the circumferential direction, circumference can be classified into stagnation, thin liquid film, hydraulic jump, stable flow path, and dripping regions. Local convective heat transfer coefficient first drops and subsequently increases marginally along the circumferential direction, while decreasing monotonically along the axial direction. The effect of impact height and outlet Re on local convective heat transfer coefficient is manifested mainly in stagnation, thin liquid film, and hydraulic jump regions. For outlet Re = 984, as impact height rises to a certain degree, there are apparent enhancements of the liquid film perturbation and convective heat transfer performance. Finally, the local Nusselt number correlations in different circumferential regions were proposed.

Experimental Measurement and Theoretical Prediction of Bubble Growth and Convection Heat Transfer Coefficient in Direct Contact Heat Transfer

The measurement of the two-phase contact area is very important to determine the heat transfer coefficient in the process of direct contact heat transfer, but the direct measurement of the two-phase contact area is a difficult problem. The experiments are carried out utilizing a cylindrical Perspex tube of 100 cm in total height and 15 cm inner diameter. The active column height throughout the experiments is taken to be equal to 50 cm. Liquid Therminol®66 with four different initial temperatures (50 °C, 60 °C, 70 °C and 80 °C) is used as a continuous phase, while liquid R245fa at a constant temperature of 23 °C is used as a dispersed phase. In this paper, the empirical correlations between bubble growth and local convection heat transfer coefficient are obtained through modeling and measurement, and its correctness is verified by experiments. The results show that the bubble diameter is positively correlated with continuous phase temperature, flow rate ratio, and height, but the local convection heat transfer coefficient is negatively correlated with continuous phase temperature, flow rate ratio, and height. At the same time, it is found that the maximum error between the actual bubble diameter and the theoretical bubble diameter is 7%, and the error between the heat flux calculated by the local convection heat transfer coefficient and the actual heat flux is within 10%. This study provides theoretical guidance for an in-depth understanding of the direct contact heat transfer process and the development of high-efficiency waste heat recovery systems.

Experiment on local convective heat transfer for successive droplets impacting on heated cylindrical surface

An experiment was conducted to investigate the underlying heat transfer mechanism when successive droplets impacting on the heated cylindrical surface. The hydrodynamics of droplets were captured by visual method and the local convective heat transfer characteristics were obtained by combining direct measurement and numerical solution of three-dimensional differential equation of heat conduction. The influences of impact frequency, impact velocity and input heat flux were experimentally discussed. It is found that, based on the evolution of local wall temperature, there are three zones along the circumference, i.e., impingement zone, heat diffusion zone and tail detachment zone. Increasing the impact frequency and input heat flux enhances the convective heat transfer performance. However, when the impact frequency is high enough, continuously increasing the impact frequency, the degree of convective heat transfer improvement gradually decreases. The increase of impact velocity mainly enhances the convective heat transfer on the impingement zone and heat diffusion zone, but has little effect on the tail detachment zone. The continuous increase of impact velocity results in the splashing phenomenon and the decrease of convective heat transfer performance. Furthermore, some dimensionless correlations were proposed for predicting the droplet splashing threshold and the local convective heat transfer performance along circumference, respectively.