Higher Heat Transfer Coefficient Research Articles

Robust Micro-Nanostructured Superhydrophobic Surfaces for Long-Term Dropwise Condensation.

Design of hierarchical micromorphology represents an important strategy for developing functional surfaces but has yet to be achieved for promising long-term dropwise condensation. Herein, micropapillaes overlaid with nanograss were created to enhance dropwise condensation. By analyzing the nucleation and evolution of the condensate droplets, we elucidated that these hierarchical micro-nanostructures topologized tapered gaps, which produced upward pressure, to achieve spontaneous dislodging of condensate microdroplet out of gaps, and then to trigger microdroplet navigation before finally departing from the surface by coalescence-induced jumping. The high mobility of condensate delayed flooding and contributed to a very high heat transfer coefficient of 218 kW·m-2·K-1. Moreover, these micropapillaes served as forts that protected the nanograss from being destroyed, resulting in improved mechanical and chemical robustness. Our work proposed new examples of topology creation for long-term dropwise condensation heat transfer and shed light on application integration of such promising functional surfaces.

Experimental analysis of high temperature flow boiling heat transfer and pressure drop in a plate heat exchanger

• High temperature flow boiling of seven working fluids is experimentally analyzed. • Two heat transfer mechanisms are identified among different working fluids. • A superposition model is developed for the heat transfer coefficient prediction. • The heat transfer coefficient of propane is up to 152% higher than that of R236fa. • Isobutane has the lowest frictional pressure drop among the seven working fluids. Organic Rankine cycle technology has gained worldwide acceptance as an efficient way to utilize low-grade heat sources. Plate heat exchangers are the most common type of heat exchanger employed as evaporators in small-scale organic Rankine cycle units, in which a high saturation temperature is the prevailing working condition. However, there is a lack of research on high temperature flow boiling in plate heat exchangers. This paper presents an experimental analysis on flow boiling heat transfer and pressure drop characteristics in a plate heat exchanger, and the development of prediction methods for the heat transfer coefficient and frictional pressure drop. Seven working fluids, R134a, R236fa, R245fa, R1234ze(E), R1233zd(E), propane and isobutane, were tested at the reduced pressures of 0.45, 0.55 and 0.65, corresponding to saturation temperatures ranging from 55 °C to 141 °C, and various mass fluxes. Two heat transfer mechanisms, nucleate boiling and thin-film evaporation, were identified in the heat transfer processes of the different working fluids, due to the diversity in their thermo-physical properties. Moreover, the results indicate that propane and isobutane have higher heat transfer coefficients than the other working fluids, while R236fa has the lowest heat transfer coefficient. The frictional pressure drops show the same characteristics for all the working fluids, increasing with the increase of the vapor quality and mass flux and the decrease of the saturation temperature. A superposition model presented in the paper achieves a good prediction for the heat transfer data, with a 12.8% mean absolute percentage deviation. A correlation developed in a previous work by the authors enables a prediction with an 11.1% mean absolute percentage deviation for the pressure drop data. The prediction methods presented in the paper will facilitate the modelling and design of plate heat exchanger evaporators in organic Rankine cycle units.

Conjugate heat transfer analysis of bubble growth during flow boiling in a rectangular microchannel

The conjugate heat transfer of bubble growth during flow boiling in microchannel has a significant effect on the flow field and heat transfer performance but few studies analyzed it before. In this study, the volume of fluid (VOF) method, Hardt's phase-change model, conjugate heat transfer between solid and fluid domains are adopted within an OpenFOAM solver to investigate the bubble growth and heat transfer performance in a microchannel with changed wall thickness from 5 μm to 160 μm and materials including silicon, aluminum, and copper. The results reveal that even if uniform heat flux is applied to the bottom wall, heat flux is not uniform at the solid-fluid interface due to the phase-change process in the channel. Conjugate heat transfer between the fluid and solid domain plays an important role in transferring the uniform heat flux from the bottom wall to the solid-fluid interface and homogenizing the solid-region temperature distribution, which cannot be ignored in the simulation of the phase-change phenomenon. When using different wall thicknesses, the bubble growth period differs by over two times. An optimum thickness exists for each material because the increasing wall thickness leads to a faster bubble growth rate but higher thermal resistance. With the same bottom wall thickness, the solid material with higher thermal diffusivity owns a faster bubble growth rate, thus a higher heat transfer coefficient. The optimum thickness decreases with increasing thermal diffusivity of the solid-domain material.

Experimental Study and Mitigation of Pressure Drop Oscillation Using Active Control

Abstract Flow boiling in microchannel evaporators is widely recognized and promising for its compact structure, lower coolant usage, high heat transfer coefficient, ability to provide higher heat fluxes, and better temperature uniformity than single-phase liquid cooling. However, critical heat flux (CHF), local dry-outs, and flow instabilities can be significant roadblocks for practical implementation. Flow instabilities, like pressure drop oscillation, could lead to nonuniform wall temperature distribution, flow reversal, and local dryout, which can be detrimental to system performance. We conducted an experimental study of a vapor compression cycle incorporating a microchannel evaporator to investigate the role of evaporator design and various system parameters on the overall performance. These parameters include the expansion valve setting, the accumulator heat load, and the evaporator heat load. While the evaporator design, the testbed, and system parameters affect the system response in unique ways, flow instability can be explained based on the overall pressure drop occurring in the system and how it varies as a function of these factors. Based on the understanding gained from this experimental study, a dynamic control strategy was developed to stabilize the system facing transient heat loads. The system can successfully address transient evaporator heat loads with feedforward control, which would otherwise lead to pressure drop oscillation. We believe this study can be helpful in further development of active control techniques to achieve multiple objectives of maintaining fixed evaporator temperature, allowing higher cooling rates, avoiding CHF, and suppressing flow instabilities, even in the presence of transient heat loads.

Theoretical Analysis of Thin Film Evaporation in the Wicks of Loop Heat Pipes

Abstract In this paper, a thin film evaporation model that includes expressions for energy, mass, and momentum conservation was established through the augmented Young–Laplace model. Based on this model, the effects of pore size and superheating on heat transfer during thin film evaporation were analyzed. The influence of the wick diameter of the loop heat pipe (LHP) on the critical heat flux of the evaporator is analyzed theoretically. The results show that pore size and superheating mainly influence evaporation through changes in the length of the transition film and intrinsic meniscus. The contribution of the transition film area is mainly reflected in the heat transfer coefficient, and the contribution of the intrinsic meniscus area is mainly apparent in the quantity of heat that is transferred. When an LHP evaporator is operating in a state of surface evaporation, a higher heat transfer coefficient can be achieved using a smaller pore size.

Characteristics of Refrigerant Boiling Heat Transfer in Rectangular Mini-Channels during Various Flow Orientations

This paper reports the results of heat transfer during refrigerant flow in rectangular mini-channels at stationary conditions. The impacts of selected parameters on boiling are discussed, i.e., thermal and flow parameters, dimensions and orientation of the channels. Four refrigerants (FC-72, HFE-649, HFE-7000 and HFE-7100) were used as the working fluid. Research was carried out on the experimental set-up with the test section with a single rectangular mini-channel of 180 mm long and with a group of five parallel mini-channels, each 32 mm long. The temperature of the mini-channel’s heated wall was measured by infrared thermography. Local values of the heat transfer coefficient at the contact surface between the fluid and the plate were calculated using the 1D mathematical method. The results are presented as the relationship between the heat transfer coefficient and the distance along the mini-channel length and boiling curves. Two-phase flow patterns are shown. Moreover, the results concerning various refrigerants and the use of modified heater surfaces are discussed. The main factors influencing the heat transfer process were: mini-channel inclination to the horizontal pane (the highest heat transfer coefficient at 270° and 0°), using modified heater surfaces (especially electroerosion texturing and vibration-assisted laser No. 2 texturing) and working fluids (FC-72 and HFE-7000).

Thermal and thermo‐hydraulic behaviour of alumina‐graphene hybrid nanofluid in minichannel heat sink: An experimental study

Thermal and pressure drop aspects of a minichannel heat sink have been investigated experimentally using distilled water as base fluid with alumina, graphene and alumina-graphene hybrid composition at 0.01% volume concentration. The reasons to select alumina-graphene as a potential nanomaterials combination for hybrid nanofluids are as: (i) thermal conductivity enhancement and (ii) to investigate the effect of morphology (shape and size of nanoparticles). Alumina (Al2O3) is oxide and has spherical shape whereas graphene is allotrope of carbon and has platelet shape. To examine the effect of different nanoparticles (in terms of shape, size and properties) dispersed hybrid nanofluid on hydrothermal bahaviour is an interesting study. Effects of Reynolds number (80-450), flow rate (0.1-0.5 L/min) and fluid inlet temperature (20-40°C) are studied. The effects of uniform heat flux of 50 and 66.7 W/cm2 on hydrothermal behaviour of a minichannel are also examined. The increment in convective heat transfer coefficient (HTC) is 30.93% at 30°C with graphene/water composition nanofluid than water base fluid. A penalty of 23.82% has been observed in pressure drop with graphene/water nanofluid over base fluid. As inlet temperature increases, Nusselt number (Nu) increases while adverse effect is found in case of friction factor. Performance evaluation criteria (PEC) has been observed more than 1 for all nanofluids and hybrid nanofluids, which ensured that nanofluids act as a better electronic cooling agent than water. Al2O3 + graphene hybrid nanofluid delivers optimum comparison factor (HTC to pressure drop ratio) and lower entropy generation rate among used working fluids. Graphene/water nanofluid yields less comparison factor compared to other working fluids irrespective of high HTC. h/Δp is favourable for nanofluid of unlike particles of hybrid composition (in terms of particle size, properties and shape) as compared to mono nanofluid and hybrid nanofluid having similar particles.

Coupling between oxidation kinetics and anisothermal oil flow during deep-fat frying

Deep-fat frying is a cooking technique that has been used continuously since prehistoric times. A domestic deep-fryer heated from the bottom develops significant convection inside the bath cavity. It is responsible for very high heat transfer coefficients and the exposure of the deep-frying oil to the atmospheric oxygen. The continuous conversion of gaseous dioxygen into unstable and reactive hydroperoxides and their subsequent advection throughout the bulk volume is at the origin of the main complaints made of frying which includes issues such as odors, fouling, and generation of several toxic compounds. This study analyzes the coupling between natural convection of triacylglycerols and the combinatorial chemistry controlling their autoxidation. At macroscopic scale, anisothermal flow within a typical kitchen appliance, including a cold zone beneath the heating element, was simulated in 3D under the Boussinesq approximation with a Eulerian description during initial heating and temperature holding. At molecular and intermediate scales, the endothermic decomposition of fatty-ester hydroperoxides in various mixtures was simulated over several hours using a Lagrangian description. Simulations and the proposed description of the combinatorial generation of hydroperoxides highlighted the complex relationship between deep-fryer design, residence times at different temperatures, and oil composition. The half-life of hydroperoxides (>15 min) is intermediate between vertical mixing times (<3 min) and longitudinal ones (>2 h). Hydroperoxides of unsaturated fatty esters are generated at the surface, which are preferentially decomposed in heated plumes and accumulate between production cycles in cold stagnant regions. Experimental validation is proposed for the eddy structure, temperature fluctuations, and hydroperoxides decomposition kinetics.

Enhanced pool boiling of dielectric and highly wetting liquids – A review on surface engineering

Dielectric liquids possess great potential for thermal management of electronic devices for containing features like environmental benign and are free from electrical hazards. One of the highly efficient cooling schemes with dielectric liquids is via pool boiling in immersion cooling. The present study reviews role of surface engineering in enhanced pool boiling highly wetting dielectric liquids. The current review consolidates the data of pool boiling of engineered surfaces in terms of heat transfer coefficient (HTC), critical heat flux (CHF), and temperature excursion. The engineered surfaces are classified with respect to their fabrication techniques (additive, subtractive, or combined). The enhanced pool boiling performance of these engineered surfaces is reported and discussed for both saturated and subcooled testing conditions. Also, discussions are made on some of the engineered surfaces that deteriorate the performance subjected to pool boiling of dielectric liquids. The promising engineered surfaces in terms of improved boiling performance (higher HTC and CHF) are highlighted as well. Moreover, the existing prediction methods (correlations, mechanistic models, and artificial intelligence based models) are evaluated. Finally, the research gaps in the pool boiling of dielectric liquids in terms of the surface engineering along with the prediction methods are identified.

Hybrid model of thin film boiling: Insights into the unique behavior and ultrahigh heat flux

Ultrahigh heat flux of over 1 kW/cm2 can be achieved by a new thin film boiling regime, of which the variation of boiling curve is considerably different from that of pool boiling. However, there is a lack of quantitative analysis for the distinctive thin film boiling. In this work, comprehensive comparison was made between the well-studied pool boiling and the newly-achieved thin film boiling. The boiling curve of thin film boiling was divided into three segments and mathematical models were set up for each segment in a way that correlations for pool boiling were adopted and modified according to the similarity and difference between pool boiling and thin film boiling, respectively. It was found that the modeling results agreed very well with the experimental results, indicating that the hybrid model revealed the underlying mechanism for the unique behavior and ultrahigh heat flux of the thin film boiling. In brief, the higher heat transfer coefficient or larger slope of the boiling curve was related to the special water supply mode of thin film boiling, in which the water flowed vertically through the heat surface and consequently enhanced heat transfer by promoting the spread of superheated layer and the bubbles on the heating surface. As for the ultrahigh heat flux and the unique negative slope of the boiling curve, it was attributed to the very thin yet continuously decreased thickness of the liquid layer, which was another essential feature of the thin film boiling. The hybrid model in this work can provide both quantitative insight for fundamental understanding and future guidance for practical application of thin film boiling.

Thermal-hydraulic-structural evaluation of S–CO2 cooling wall tubes: A thermal stress evaluating criterion and optimization

The S–CO2 Brayton cycle has been considered as a promising alternative in coal-fired power plants due to its high efficiency and high compactness. However, the high inlet temperature and low heat transfer coefficient of S–CO2 in the cooling wall tubes arranged in the furnace could lead to thermal fragile in practical operation. In present study, thermal-hydraulic-structural evaluation on S–CO2 cooling wall tubes is investigated. Firstly, it is found that the stress distribution is mainly dominated by the circumferential temperature gradient. Secondly, a new criterion, the thermal deviation factor (TDF), is proposed to evaluate the tube thermal stress. It indicates the plastic deformation if exceeding the critical value of TDF = 1, which is more efficient than conventional structural analysis. Thirdly, based on the TDF, two typical methods of inserting twisted tapes and unilaterally arranging dimples inside the tube are proposed to reduce the thermal stress. A novel configuration of elliptic dimple with rounded corners is finally proposed to reduce the local stress concentration efficiently. The results show that the elliptic dimples have the highest comprehensive performance, which is recommended as the heat transfer enhancement structures in S–CO2 cooling wall tubes.

Experimental and Numerical Heat Transfer Investigation of Impingement Jet Nozzle Position in Concave Double-Wall Cooling Structures

In this paper, experimental and numerical study has been carried out to investigate impingement cooling with a row of five circular jets, varied between target positions on a realistic leading edge region of gas turbine blade geometry. Experimental data is collected from a transient thermochromic liquid crystal measurement technique at the target surface. Numerical study was conducted with the geometry using commercial computational fluid dynamics software to analyze the fluid flow. The unique aims of the study are to observe the effects of variation in jet location, and those specific to realistic target and nozzle geometries. Distributions of local and average Nusselt number show that a location targeting the concave surface at 90° demonstrates an overall higher heat transfer coefficient, especially in the stagnation region, and toward the airfoil sides, with significantly fewer swirls. The experiment was performed with the following parameters: distance from nozzle to target of 1.7 to 2.1 jet diameters, pitch between jets of 4.4 jet diameters, and concave target diameter of 8.0 jet diameters. The jet Reynolds number range during this test was 20,000 − 40,000. A standard flat target plate impingement test is also experimentally conducted and compared against existing literature for method validation.

Heat Transfer Characteristics Analysis on a Fully Cooled Vane With Varied Density Ratios

Abstract The objective of this experimental investigation was to determine the cooling performance of a fully cooled vane with 18 rows of cylinder cooling holes. The exit Reynolds number in the wind tunnel normalized by the true chord was 500,000 with an inlet turbulence intensity of 15%. The film cooling effectiveness and heat transfer coefficient distribution were obtained by the transient liquid crystal (TLC) technology, three mass flow ratios (MFRs = 7.0%, 9.9%, 11%) and two density ratios (DRs = 1.0, 1.5) were tested. The results show that the film cooling effectiveness distribution on the suction side is more uniform and the coolant injection trajectory is much longer than that on the pressure side. As the density ratio increasing to 1.5, the more laterally uniform film cooling effectiveness contour on the pressure side is observed and the spatially averaged film cooling effectiveness is increased by 11–43%. For the MFR = 7.0%, the coolant injection with low momentum thickens the boundary layer and reduces the heat transfer coefficient in the mid-chord region of the pressure side. Both the increased mass flow ratio and decreased density ratio result in a higher heat transfer coefficient, while do not alter the distribution trend. By calculating the heat flux ratio, the reduction in the heat flux at DR = 1.5 is found to be within 20% in most areas than that of DR = 1.0 on the vane surface.

Heat transfer characteristics of closed-end thermosyphon (CE-TPCT)

This study investigated the heat transfer characteristics of a Closed-End Thermosyphon (CE-TPCT) made of copper tubes with 5.5 mm diameter. The experiments were conducted with working substance filling rates of 0%, 30%, 50%, and 70% of the volumetric evaporator section, the evaporator temperatures of 50, 70, and 90 °C and inclination angle of 90°. The lengths of the evaporator section, adiabatic section and condenser section used in the experiments were 60 mm, the distance between the compartments was 5Di. Water was the working substance used in the experiments with the mass flow rate of the water inlet at the condenser section of 0.25 L/min. The water inlet temperature at the condenser was 20 °C. Obtained results were compared with convectional Thermosyphon (TPCT) which was tested under the same conditions. The results showed that CE-TPCT at the filling rate of 70% at the evaporator section volume had an average heat transfer rate and average heat flux of 140.72 ± 4.92 W and 33.41 ± 1.16 kW/m2, respectively, throughout the experiment. These results were higher than the other tested parameters. The highest heat transfer rate of 220.32 ± 7.71 W and average heat flux of 52.31 ± 1.83 kW/m2 were recorded at the evaporator temperatures of 90 °C. The experiment also showed a lower average total thermal resistance throughout when it was compared with other test parameters which was equal to 0.547 °C/W. This resulted in high heat transfer coefficients and relative thermal efficiency of 625.11 W/m2·°C and 1 respectively, the highest value of all studied experimental variables. When the maximum heat flux results between CE-TPCT and TPCT under the same condition parameters were compared, CE-TPCT demonstrated a higher heat flux value of 18.24%. The heat transfer characteristics of the CE-TPCT obtained from this study provides an alternative application choice for various types of heat exchanger that can reduce energy consumption in the future.

CFD simulation of the impact of tip clearance on the hydrothermal performance and entropy generation of a water-cooled pin-fin heat sink

In this paper, the 3D numerical calculations of the water flow inside a pin-fin heat sink (PFHS) to determine the influence of tip clearance on the hydrothermal behavior and frictional & thermal irreversibilities of the fluid flow. The numerical simulations were conducted for five different fin heights (ξ = 1.5 mm to 2.5 mm) considering four different Reynolds numbers (Re=500, 1000, 1500, and 2000). The results demonstrated that the highest heat transfer coefficient is associated with ξ = 2.25 mm due to more uniform vorticity distributions, while the minimum central processing unit (CPU) average temperature is obtained for ξ = 2.5 mm due to the higher heat transfer surface area. The minimum thermal and frictional entropy generation rates are associated with PFHS with ξ = 1.5 mm. However, the PFHS with ξ = 2.25 mm has the highest Performance Evaluation Criterion (PEC) of nearly equal to 1.28 as compared to the other ξs. Besides, the fluid flow from the pin-fin base to the top and vice versa leads to create the vortices especially at the entrance of the PFHSs with tip clearance.

Heat transfer characteristics of horizontal tubes in the dilute phase of the pressurized fluidized bed

When the membrane wall water tubes and immersed tubes heat exchanger cannot effectively control the furnace temperature, arranging the horizontal tubes in the dilute phase is a method to solve the limited layout of the heat exchanger area. In order to study the heat transfer characteristics of the horizontal tubes in the dilute phase, the local and average heat transfer coefficients (HTC) were measured based on the pressurized fluidized bed apparatus under different pressures, particle sizes and gas velocities. The experimental results showed the improved heat transfer at elevated pressure and high gas velocities. The heat transfer tube with a lower height position had higher heat transfer coefficients because of the particle concentration effect. Under the same system pressure, the circumferential HTC of the horizontal tube were slightly higher at 0° and 180° circumferential positions, but the overall distribution tended to be uniform. Based on the experimental results, an empirical model for the average heat transfer coefficient prediction was developed and can predict 97.4% of the experimental data from this study and other different sources within 25% error with the absolute average deviation of 8.18%. This work can provide reliable experimental data for the design of heat exchanger tubes in dilute phase zone of pressurized fluidized bed and existing model verification. Also the correlation proposed in the paper can be translated to CFD code for further application.

냉각 채널 내 방열핀을 활용한 전기자동차 구동 모터의 냉각 성능 향상을 위한 스마트 냉각 시스템 설계

This research is to investigate the cooling performance of the motor in the electric vehicle depending on the cooling channel fin. The research focused on numerical study of the temperature of coil and cooling channel and the heat transfer coefficients to find a optimum design shape with high cooling performance at three different cases. To compare the convective cooling performance of the three cooling channels, local position (R) are displayed on the surface of the coils with a large temperature deviation. This research was performed on forced convection and was numerically analyzed by FLUENT V20.2. Owing to forced convection by the same mass flow, the average cooling channel velocity in Case 3 was 17.4% faster than Case 1 and 8.6% faster than Case 2. Out of the three cases, the highest heat transfer coefficient was found in the cooling channel and coil of Case 3, which had two cooling fins. The coil maximum temperature of Case 3 with 2 cooling fins was 4.7% lower than Case 1 without cooling fins and 1.7% lower than Case 2 with 1 cooling fin. Ultimately, Case 3 with two cooling fins provided the best cooling performance and improved driving motor performance for motor durability.

A study on heat transfer characteristics by impinging jet with several velocities distribution

Impinging jet is well known as the most effective cooling method of a heated surface, since it has a high heat transfer coefficient. In this paper, the heated plate surface is going to be cooled by impinging jet through the heat transfer coefficient enhancement. An air flow with several patterns of velocities is suitable for rapid cooling. Therefore, this method is treated as cooling of thermal systems.The objective of this research consists of improving the heat transfer by air jet flow at proper velocity and adequate distances of collision in order to ensure efficient cooling.In this paper, the measurement of velocity distribution by pitot tube is going to be investigated, the flow visualization by high speed camera and finally the heat transfer characteristics on the heated surface by the impinging jet when changing the distance to the collision plate X/D and the air flow velocities distributions. The experimental results indicate that, the collisions distances X/D = 4, 7 and 9 at velocity 15 m/s compare to others values have the highest heat transfer coefficient rate.

Thermal performance improvement of microchannel heat sinks by utilizing variable cross-section microchannels filled with porous media

This study presents optimal design of microchannel heat sinks (MCHSs) by utilizing variable cross-section microchannels filled with porous media to improve the MCHS thermal performance. A parametric optimization has been carried out based on varying coolant passage widths and heights with or without a porous material, regarding two different objectives: an average heat transfer coefficient and pumping power. Results indicate that the coolant passage enlargement has a positive impact on reducing the required pumping power. Although the coolant passage's width enlargement causes a slight drop in the heat transfer coefficient, the coolant passage's height extension provides a higher heat transfer coefficient. In addition, the porous material has a significant effect on reducing pumping power; however, it causes a slight reduction in the heat transfer coefficient. The results reveal that there is an optimum design for MCHS with a porous material. Numerical optimization carried out at Reynolds numbers ranging 140–560, shows better performances at higher Reynolds numbers; however, the effectiveness of utilizing variable cross-section microchannels and porous media are less pronounced when the Reynolds number increases. Utilizing variable cross-section microchannels filled with and without porous media is found to enhance conventional microchannel heat sinks performance up to 90% and 40%, respectively.

Numerical investigation on the influence of installation angle of inclined interrupted fins heat sink on heat dissipation performance

Numerical simulations of a symmetric array of inclined fins heat sink under natural convection had been carried out using the ANSYS icepak to solve the complete Navier-Stokes equation and the energy equation in the current study. The effects of fin height (20 mm ≤ H ≤ 40 mm) and heat sink installation angle (–45° ≤ φ ≤ 30°) were analyzed. The work fluid was the air. The results showed that when the input power was constant, as the fin height increased, the heat transfer performance improved. There was no better heat transfer performance than the case of fin height was 40 mm, of which the corresponding heat transfer resistance was also almost the lowest. Compared with H = 20 mm and H = 30 mm, the case of H = 40 mm can reduce the average substrate temperature by 5%−10%. The installation angle greatly affected the heat transfer performance of the heat sink. Compared with the negative installation angle, the positive installation angle showed stronger inhibition on the heat dissipation. The installation angle of −15° showed the highest heat transfer coefficient, which could improve the heat transfer coefficient by about 7%. The Nusselt number (Nu) was found to increase approximately linearly with the Rayleigh number (Ra) in the range of 8.5 × 106 ∼ 1.64 × 107. A correlation between Nu and Ra, the geometric parameters of fin arrangement and the dimensionless correlations related to the heat sink installation angle were obtained. Highlights A new type of fin heat sink was proposed to improve heat sink performance. The heat sink installation angles was studied with the best angle found. The correlation formula related to the installation angle was obtained.