Maximum Thermal Resistance Research Articles

Design and experimental analysis of a novel thermal diode with asymmetric heat transfer inspired by feather

To overcome the limitation of isotropic heat transfer of traditional heat pipes, a novel thermal diode with asymmetric flow resistance vapor channel inspired by the goose feather fibers is proposed in this study. The thermal performance of novel thermal diode is experimentally investigated. Results show that under the wide range of operating conditions, the thermal resistance of one end surpasses the thermal resistance of the other end, indicating its excellent thermal rectification capability. Under the filling ratio of 10 % and heating power of 7.5 W, the maximum thermal resistance of the thermal diode is 5.23 times the minimum thermal resistance, demonstrating excellent asymmetric heat transfer performance. Experimental results demonstrate that the novel thermal diode proposed in this study can easily change its unidirectional heat transfer direction by simply adjusting the internal filling ratio, showing significant application potential in the fields of thermal control system.

Analyzing the Effect of Yarn Tension, Weft Yarn Type, and Weft Yarn Density on Thermal Resistance, Thermal Conductivity, and Air Permeability of Plain Woven Fabric

ABSTRACT Uncomfortable feelings during wear highly affect human health, work efficiency, and mental satisfaction. This study evaluated the thermal comfort of woven fabrics made from 16Ne ring and rotor spun weft yarns(x1). The other variables involved are warp tensions (x2) of 1 kilo newton (KN) and 2 kN, weft tensions (x3) of PFT/B- and PFT/B+T, and weft densities (x4) of 14 picks per centimeter (PPC) and 18 PPC. Comfort properties such as thermal conductivity, thermal insulation, and air permeability were measured and analyzed. The fabric produced from rotor-spun weft yarn showed better thermal comfort properties than the fabric made from ring-spun weft yarn. The results of the analysis revealed that when warp and weft yarn tension increased and weft density decreased, thermal conductivity and air permeability also increased. However, thermal insulation of the fabric decreased as yarn tension increased. On the other hand, as the weft density increased, the thermal insulation of the fabric increased. Air permeability increased as weft tension increased from PFT/B- to PFT/B+T and it decreased as weft density increased from 14 PPC to 18PPC. The maximum thermal conductivity and minimum thermal resistance were attained at 14 PPC weft density and ring-spun weft yarn.

Optimization of Heat-Dissipation Structure of High-Power Diode Laser in Space Environments.

The high-power laser diode (HPLD) has witnessed increasing application in space, as the aerospace industry is developing rapidly. To cope with the space environment, optimizing the heat-dissipation structure and improving the heat-dissipation ability via heat conduction have become key to researching the thermal reliability of the HPLD in space environments. Based on a theoretical analysis of the HPLD, a simulation model of the HPLD was constructed for numerical simulation, and it was found that the maximum temperature and thermal resistance of lasers were efficaciously decreased by changing the packaging position of laser bars. The packaging position of the bars and the cutting angle of the microchannel heat sink (MCHS) were determined based on the light-emitting angle of the light-emitting unit and the internal structure of the MCHS. The internal structure of the MCHS was optimized through a single-factor experiment, an orthogonal experiment, and the combination of neural networks and genetic algorithms (GAs), using three key structural parameters, namely the MCHS ridge width, W1, the channel width, W2, and the channel length, L1. After optimization, the performance of the MCHS was obviously improved. Finally, an analysis was carried out on the applicability of the optimized MCHS to bars with a higher power.

Heat transfer performance of the vapor chamber with spiral support-composite wick

Inefficient heat dissipation in vapor chambers (VCs) is a major challenge for their development and application. To investigate the effect of supports on VCs’ maximum thermal power and thermal resistance, the relationship between the number of supports and the vapor channel pressure drop is studied through pressure drop measurement. Composite Wick Vapor Chambers (CWVCs) with various supports are fabricated and tested with a constructed thermal performance test platform. The results indicate that the heat transfer performance of CWVC is related to the number of supports and the liquid filling ratio. The optimum filling ratio of the composite wick with 3-6 spiral supports (SS3-SS6) is 60%, 70%, 90%, and 70%, with corresponding maximum thermal power of 19.25 W, 25.61 W, 25.97 W, and 21.22 W. The thermal resistance of SS4-CWVC is lower overall. Additionally, when the power is 21 W, the surface temperature difference of the condenser of SS3-CWVC and SS6-CWVC is 2.3 °C and 1.3 °C, respectively. However, the condenser surface temperature difference of SS4-CWVC is 66.5% lower than that of SS3-CWVC and 40.8% lower than that of SS6-CWVC at the same power. Therefore, SS4-CWVC exhibits better temperature uniformity and has better heat transfer performance.

Multi-objective optimization of weight reduction process parameters of micropolyester woven fabrics using Taguchi gray relational analysis

The weight loss process variables of alkali-treated micropolyester woven fabrics were optimized and reported in this study. The gray relational analysis with the help of the Taguchi technique was efficiently used to optimize the key variables of this process. The caustic soda concentration, treatment temperature, and weight loss machine speed were considered the control or design parameters. The weight reduction percentage, air permeability, tensile strength, and thermal resistance of alkali-treated woven polyester fabrics were also considered as responses in this study. The experiments were implemented according to a 33 full factorial design. The levels of the control parameters which yield the maximum weight reduction, tensile strength, air permeability, and minimum thermal resistance of the treated polyester fabrics were found to be the sodium hydroxide concentration, and treatment temperature with the highest levels, and machine speed with the lowest level. This means that a 27% caustic soda concentration, treatment temperature of 125°C, and machine speed of 40 m/min exhibited the optimum properties of the treated micropolyester fabrics. It was also proved that the treatment temperature is the most influential factor affecting the micropolyester fabric’s properties. The confirmation test, which was carried out in this study, confirmed that the gray relational analysis improved the alkali-treated polyester fabric properties.

Sensitivity Analysis and Optimization of Heat Transfer Performance of Ultra-Thin Vapor Chamber With Composite Wick

Abstract An ultra-thin vapor chamber (VC) with the composite wick formed by four spiral woven meshes (SWMs) and a copper mesh was proposed to solve the heat dissipation problem in miniaturized electronic equipment because of its sufficient heat transfer capability under limited thickness. However, the influence factors on the thermal performance of the VC with composite wick are more than that of the VC with a single type of wick. In this study, in order to investigate the thermal performance of the VC with composite wick, a theoretical model was developed to calculate the maximum heat transfer capacity. Besides, a three-dimensional numerical model for the heat transfer characteristics was established, and the simulation results have a good match with the experimental results. The orthogonal test method was adopted to determine that both the width of the vapor channel (wv) and the thickness of the vapor channel (tv) have a significant effect on the maximum heat transfer capacity and thermal resistance, while the porosity of the mesh (εmesh) has a prominent effect on the maximum heat transfer capacity, but has little effect on the thermal resistance. Further optimization of the sensitive factors for VC heat transfer performance was achieved to enhance the maximum heat transfer capacity.

Enhancing heat transfer performance of aluminum-based vapor chamber with a novel bionic wick structure fabricated using additive manufacturing

Given the lightweight nature and excellent thermal conductivity of aluminum, it offers significant potential for light-weighting of phase-change cooling components. To further enhance the thermal performance of aluminum-based vapor chambers, this study utilized selective laser melting (SLM) to design and integrally manufacture the slightly oleophilic wick for the condenser of the aluminum-based vapor chamber, along with three different superoleophilic wick structures for the evaporator: the gyroid bionic composite porous wick vapor chamber (GBCPVC), the groove composite porous wick vapor chamber (GCPVC), and the uniform porous wick vapor chamber (UPVC). A water-cooling experimental setup was established, and the effects of wick structure, cooling water flow rate, and cooling water temperature on the maximum heat load, temperature uniformity, and thermal resistance of vapor chambers were systematically investigated. The results indicated that the gyroid bionic porous wick structure significantly enhanced the thermal performance of the vapor chamber. Under the same conditions, GBCPVC exhibited lower thermal resistance and superior temperature uniformity, achieving a higher heat load than GCPVC and UPVC. When the cooling water temperature was decreased, its maximum heat load significantly increased. Specifically, at 15 °C, the maximum heat load for GBCPVC reached 300 W, an increase of 33.33 % and 53.33 % compared to 25 °C and 35 °C, respectively. Conversely, a rise in cooling water temperature enhanced the temperature uniformity and reduced thermal resistance of CBCPVC. At 35 °C and a heat load of 120 W, GBCPVC achieved a minimum thermal resistance of 0.034 K/W and a maximum temperature difference of 1.46 °C. Additionally, an increased flow rate enhanced the maximum heat load of GBCPVC, and under high heat loads, it could also reduce the thermal resistance and improve temperature uniformity. This study provides new insights and solutions for the thermal management of phase-change cooling components in aerospace electronic devices.

Research on the thermal performance and stability of three-dimensional array pulsating heat pipe for active/passive coupled thermal management application

The efficient heat transfer performance of three-dimensional pulsating heat pipes can effectively deal with the heat dissipation problems in the field of electronics integration. However, the large contact thermal resistance and complex layout limit the actual cooling efficiency. In this study, a novel three-dimensional array pulsating heat pipe (3D-APHP) with a dual-plane structure was designed. The top and bottom of the 3D-APHP are mounted with flat plates, and the center section is connected by multiple parallel array tubes. The planar and array structures enhance the flexibility in the actual layout of the pulsating heat pipe to accommodate space constraints. The effects of different conditions (working fluid, filling rate, heating power, tube diameter and installation condition) on the heat transfer performance and uniform temperature performance of 3D-APHP were investigated. It is found that 3D-APHP demonstrates efficient heat transfer capability and temperature uniformity. The minimum thermal resistance and maximum thermal conductivity can reach 0.059 °C/W and 170.1 KW/m °C, respectively. Moreover, 3D-APHP exhibits good heat transfer performance across different installation positions with a maximum thermal resistance not exceeding 1.1 °C/W, revealing significant potential for applications. Meanwhile, the two-phase heat transfer process inside the 3D-APHP was analyzed. The uniform vapor–liquid plug distribution can significantly strengthen the thermal performance of the 3D-APHP.

A new microlayer depletion model for numerical simulation of bubble growth during nucleate boiling

In this study, a new microlayer depletion model was developed to simulate bubble growth during the nucleate boiling of water and ethanol. By improving the coupled volume-of-fluid and level set model, the macro-two-phase flow was accurately tracked, eliminating velocity jumps at the interface. The proposed model was validated against pool boiling measurements in water and ethanol at atmospheric pressure. The results demonstrated that the microlayer contributed approximately 15 and 33.17 % to the growth of water and ethanol bubbles, respectively. Under the influence of the interfacial temperature, the mass accommodation coefficient of water could vary from 0.004 to 0.027. Considering the impact of the interfacial temperature on the mass accommodation coefficient could reduce the prediction error of the evaporative thermal resistance from 17.2 to 4.67 %. Furthermore, the study revealed that the evaporative thermal resistance of the water is comparable to the microlayer conductive thermal resistance, whereas the maximum evaporative thermal resistance of ethanol is less than 5 % of the microlayer conductive thermal resistance and can be neglected.

Numerical Investigation on Thermal Performance of Nanofluid-Assisted Wickless Heat Pipes for Electronic Thermal Management

Abstract Heat pipes are passive heat transfer systems and serve as an effective thermal management solution for electronic devices. The adaptability of heat pipes makes these suited for a wide application range, especially in the field of electronic thermal management. The current study highlights the transient numerical analysis of wickless heat pipes (thermosyphons) for the thermal management of electronic devices. The thermal performance of the thermosyphon is analyzed using both copper oxide (CuO) and aluminum oxide (Al2O3) nanofluids with their concentrations at 1% and 5%. Deionized (DI) water is employed as a reference case for comparison. The study is carried out for variable heat inputs to the thermosyphon ranging 10–50 W for a time interval of 30 s. The idea is to analyze the effect of the evaporator heat input and the nanoparticles concentration on the temperature, heat transfer coefficient, thermal resistance, and effective thermal conductivity of the heat pipe. The results indicate that CuO nanoparticles at a 5% concentration lead to a maximum thermal resistance reduction of 4.31% at 50 W, while alumina nanoparticles at the same concentration lead to a more substantial reduction of 6.66% at the same heat load. The evaporator temperature varies between 377.52 K to 374.99 K using deionized water, and 376.95 K to 374.29 K using CuO nanofluid (at 1% concentration). The heat pipe's evaporator attains its highest convective heat transfer coefficient (437.91 W/m2K) by using alumina nanofluid with 1% nanoparticle concentration at 50 W. Moreover, the effective thermal conductivity of the heat pipe is enhanced by 5% and 7% for copper oxide and aluminum oxide nanofluids (with 5% concentration), respectively, at 50 W. Thus, the nanofluids play a significant role in improving the efficiency and reliability of electronic components. These findings demonstrate the potential of using the nanofluids in thermosyphons to enhance their thermal performance in electronic cooling applications.

Analysis and assessment of electrical and thermal performance of five‐phase voltage source inverter under different modulation strategies: Comparative study under balanced and unbalanced load

SummaryThis paper compares four modulation strategies applied to five‐phase voltage source inverters (5PH‐VSI). The modulation strategies under investigation are sine wave pulse width modulation (S‐PWM), fifth‐harmonic injection PWM (FH‐PWM), space vector‐PWM using two large vectors (2V‐SVPWM), and space vector‐PWM using two medium and two large vectors (4V‐SVPWM). The study utilizes simulations to analyze the results based on four performance criteria: low‐order harmonics (LOH), maximum modulation index (MMI), common mode voltage (CMV), and total harmonic distortion (THD) under balanced and unbalanced load. To validate the simulation results for these criteria, an experimental test‐bench is employed, which includes a 5PH‐VSI feeding an R‐L load, and controlled by a low‐cost STM32F4‐DISCOVERY microcontroller board. Additionally, a mathematical approach is used to calculate the total thermal losses (TTL) then simulations are performed using Piecewise Linear Electrical Circuit Simulation (PLECS) software to assess the modulation schemes based on additional thermal performance criteria: conduction losses (CL), switching losses (SL), TTL, the efficiency, and the maximum permissible heat sink thermal resistance (MPHTR) at the steady‐state regime. The results indicate that the 4V‐SVPWM method demonstrates superior efficiency in terms of THD. Furthermore, it showcases the lowest TTL at high switching frequencies, allowing for the best efficiency and minimizing MPHRT, therefore providing the largest margin for the heat sink thermal resistance design. On the other hand, the 2V‐SVPWM offers the highest MMI, but this comes at the cost of high TTL and some LOHs appearing. In addition, it exhibits the highest CMV for unbalanced load. S‐PWM and FH‐PWM offer the advantage of simpler implementation.

Efficient thermal management of high-power electronics via jet-enhanced HU-type manifold microchannel

To efficiently remove the increasingly higher heat fluxes from electronic chips, this numerical study presents an embedded single-phase water-cooled heat sink which consists of a microchannel layer and a jet-enhanced HU-type manifold layer. The manifold features two liquid inlet plenums symmetrically positioned on two opposite sides and some outlets arranged in the middle. In order to reduce the average thermal resistance, the fluid impinging velocity is boosted by narrowing the manifold channel inlet. However, narrower inlet also leads to flow maldistribution which increases the maximum thermal resistance. To address this problem, we demonstrate two approaches: either adding a flat plate at the manifold outlet or adjusting the manifold channel walls to form a tapered pathway. Further, the impact of the plenum and manifold channel inlet profiles on fluid flow and heat transfer is investigated. Negligible difference is found between rectangular and trapezoidal plenums. As to the manifold channel inlet, although similar heat transfer performance is obtained with different shapes, the total pressure drop can be substantially different. To reduce the large pressure drop at the inlet, a semicircular or triangular inlet profile is preferred, instead of a rectangular one. Quantitatively, we show that for a 3 × 3 mm2 heated area, our heat sink can dissipate fluxes up to 2000 W cm−2 with a maximum temperature rise of 65 K and a pressure drop below 40 kPa, which represents one of the highest performances and energy efficiencies reported to date.

Transient simulations and theoretical modeling of near-junction heat conduction in GaN-on-diamond HEMT

Under high-power working conditions, accurate predictions of the maximum temperature and thermal resistance distribution in devices during transient states are essential for monitoring the health status of the devices. In this work, the heat conduction characteristics of GaN-on-diamond high electron mobility transistors (HEMTs) near the junction region under transient conditions with thermal impedance are systematically investigated with the aid of finite element simulations and thermal impedance analyses. The effects of pulse characteristics, thermal properties of different layers on the maximum temperature and thermal resistance of the device are discussed specifically. The results show that pulse characteristics have a significant effect on the maximum temperature of the device. The shorter the pulse switching time is, the higher the maximum temperature will be. Regarding the effects of the thickness of the GaN layer, the maximum temperature initially decreases and then increases, with the lowest maximum temperature observed at 1.7 μm. As the TBR increases uniformly from 10 to 40 m2K/GW, the temperature increases by approximately 4 % per 10 m2K/GW. The analyses on the thermal resistance show that the GaN layer occupies the largest proportion of thermal resistance, while the diamond substrate occupies the smallest. The optimal substrate thickness is obtained by analyzing the thermal penetration depth in the substrate for working conditions with various pulse widths. For diamond substrate, the optimal thickness at a pulse width of 5 μs is about 25 μm, and increases as the increase in pulse width. At the end, a modified Cauer RC model is proposed for predicting the transient maximum temperature based on heat spreading analysis. The difference between the maximum temperatures predicted by the model and the finite element simulations is within 8 %.

Experimental study on heat transfer from rectangular fins in combined convection

Combined natural and forced convective heat transfer arise in many transport processes in engineering devices and in nature, which is frequently encountered in industrial and technical processes, including electronic devices cooled by fans, heat exchangers placed in a low-ve-locity environment, and solar receivers exposed to winds. In this study, the effects of design parameters have been experimentally investigated for the air-side thermal performance under combined (natural and forced) convection of the rectangular plate heat sinks, and the values of optimum design parameters were sought. Many ideas for improving cooling methods have been proposed, one of which is the heat sink. In this work, the average Nusselt number (Nu) and thermal resistance of a simple base rectangular plate and five vertical rectangular plate heat sinks with different numbers of fins under natural and combined convection were exper-imentally investigated to obtain the maximum average Nu and minimum thermal resistance for various Reynolds numbers (Re) from 2300 to 40000, Rayleigh numbers (Ra) from 1300000 to 13000000, and Richardson numbers (Ri) from 0.4 to 3. Also, in this experiment, fin spacing (P) was varied from 2.8 mm to 14.6 mm and the dimensionless P/H ratio was varied from 0.1 to 0.49. The flow velocity varied in the range of 2 to 8 m/s under combined convection. Based on the effects of Ri and Re, two empirical equations for natural and also for combined con-vection heat transfer were derived to calculate the average Nu. The average deviation for these two equations is about 7%. The outcomes of this research can be beneficial for engineers who work on electronics cooling systems.

Numerical analysis of the heat transfer behaviour of a wickless heat pipe receiver for parabolic trough solar collectors

The thermal performance of a wickless heat pipe receiver for parabolic trough solar collector applications is investigated in this study. For three filling ratios of 30%, 50%, and 90%, nine different heat flux profiles were examined. The normal heat flux range was chosen to be between 58 and 288 W/m2. The influence of the non-homogeneity of the thermal flux on the receiver tube was numerically analysed for various filling ratios. The maximum average wall temperature of 390 K was observed for heat transfer profile 7 and a fill ratio of 30%. For a filling ratio of 90%, the heat flux profile 7 had a minimum thermal resistance of 0.245 K/W, and a correlation was proposed to calculate the thermal resistance. A maximum thermal resistance of 1.722 K/W was calculated for the heat flux profile 3 and a filling ratio of 30%.

Simulation Research on the Optimization of Domestic Heat Pump Water Heater Condensers

To improve the heat transfer coefficient of a condenser, this paper proposes using a fin-tube condenser to replace a smooth-tube condenser in a domestic heat pump water heater. The finite element method is used to analyze the heat transfer coefficient of fin-tube condensers with different design parameters. By comparing the results of experiments with those obtained using CFD methods, it has been determined that the CFD method used in this study is feasible. Simulation results showed that the heat transfer coefficient enhanced clearly. The total thermal resistance of the fin-tube condenser decreased by 7% through increasing fin thickness. The total thermal resistance of the fin-tube condenser increased by 1–1.3% when fin spacing was increased. The heat transfer coefficient decreased severely and the maximum total thermal resistance of the fin-tube condenser increased by 8.7% with increasing fin height. In 600 s, when the fin spacing, fin height, fin thickness and inner diameter were 14 mm, 12.5 mm, 1.2 mm and 22.5 mm, respectively, compared to the smooth-tube condenser, the fin-tube condenser could increase the final water temperature by 18.37%, and the heat transfer coefficient would increase by about 95%. This research could provide a low-cost way to improve the heat transfer coefficient of condensers in domestic heat pump water heaters.

A modified dynamic Lee model for two-phase closed thermosyphon (TPCT) simulation

A modified model consisting of a dynamic Lee model, volume of fluid model, and continuum surface force model is developed. The modified model investigates heat transfer characteristics of the vapor–liquid phase change process and details of the two-phase flow during operation of a two-phase closed thermosyphon. The mass transfer time relaxation parameters for the Lee phase change model are the most critical coefficients which determine the rate of the vapor–liquid phase change. A dynamic adjustment of the mass transfer time relaxation parameters for the Lee phase change model is realized based on the amount of mass transfer between the vapor and liquid phases and the values of the mass transfer time relaxation parameters become stabilized. The relative error between the modified model and experimental data for the temperature distribution is 5%, representing an acceptable agreement. Compared with the original model, the maximum thermal resistance errors in evaporation section and condensation section are reduced by 19.3% and 107.1%, respectively. These results indicate that the modified model can provide good corrections with high accuracy.

Design and experimental validation of a high capacity loop heat pipe for avionics cooling

With the rapid development of modern aviation industry, the power of avionics has been increasing continuously, bringing great challenge to thermal management. As an efficient two-phase heat transfer device, loop heat pipe (LHP) holds great application potential in avionics cooling. To address the issue of inadequate heat transfer capability, a set of kW-class LHP was specially designed and experimentally validated considering the airborne environment. A detailed introduction covering the entire design process was presented, in which some targeted design criteria were provided. Ammonia was chosen as the optimal working fluid, and stainless steel envelope with a nickel wick was adopted. Experimental validation showed that, at a heat sink temperature of 20 ℃, the designed LHP could achieve a maximum heat transfer capacity of 1021 W, confirming the efficacy of the design method. The average heat flux at the evaporator could reach 12.04 W/cm2. The LHP exhibited a maximum and minimum thermal resistance of 0.16 and 0.054 ℃/W, respectively, achieved at heat loads of approximately 50 W and 600 W. The maximum temperature fluctuation at the center of the saddle surface was no more than ±1.40 ℃. A method for estimating the heat leak between the evaporator and the compensation chamber was also developed, and the maximum heat leak rate was calculated to be approximately 5.2%. Moreover, the designed LHP also manifested excellent startup performance and operation stability.

Performance Evaluation and Optimization of Series Flow Channel Water-Cooled Plate for IGBT Modules

The stability in the operation of insulated gate bipolar transistor (IGBT) modules plays a crucial role in wind power generation. It is essential to improve the thermal performance of the heat sink of IGBT modules in wind power converters and reduce the power consumption of liquid cooling systems, in order to optimize the heat dissipation of IGBT modules in wind power converters. In this paper, a simulation model of the liquid-cooled heat sink of the IGBT module is established and the performance of three different series flow channel structures is compared by computational fluid dynamics (CFD). Moreover, based on the orthogonal test design, the three factors (channel width, channel height, and cold plate wall thickness) affecting the performance of the water-cooled plate were ranked and optimized. The results show that the water-cooled plate with double-helical-type flow channel structure has the best comprehensive performance. In addition, for the double-helical-type structure, the optimal combination of channel structure parameters about channel width, channel height, and cold plate wall thickness is obtained. After optimization, the maximum IGBT temperature, thermal resistance, and pressure drop of the cold plate are reduced by 3.13%, 5.78%, and 18.87%, respectively, compared with the double-S structure in parameter case one. The proposed methods and results are expected to provide theoretical guidance for the thermal management of IGBT modules in wind power converters.

Numerical study of the fluid flow and heat transfer in a finned heat sink using Ansys Icepak

Abstract This research studies a three-dimensional fluid flow, and heat transfer in the heat sink numerically using air as a coolant. The numerical effects of the number of fins and their thickness on the performance of the heat sink are investigated using Ansys Icepak. Various fin numbers and fin thicknesses are used to check the heat sink’s optimal thermal performance. The results demonstrated that the maximum temperature, pressure drop, and thermal resistance decrease with the increase in the fin number and thickness. According to the results, the optimal thickness and number of fins for the current study are 15 and 0.25 mm, respectively. Also, it is observed that increasing the number of fins has a greater effect than increasing the thickness of the fins on the maximum temperature, pressure drop, and thermal resistance.