Microchannel Heat Exchanger Research Articles

Analyzing heat transfer performance of ARCH lattice microchannel heat exchanger fabricated using selective laser melting

Analyzing heat transfer performance of ARCH lattice microchannel heat exchanger fabricated using selective laser melting

Thermal hydraulic performance and characteristics of a microchannel heat exchanger: Experimental and numerical investigations

Abstract This paper presents extensive fluid flow and Heat Transfer studies conducted through an experimental setup followed by a detailed three-dimensional (3D) numerical analysis of the same setup using a commercial package for computational fluid dynamics (CFD), known as CFD-ACE® for additive-manufactured counter-flow AlSi10Mg microchannel heat exchangers (MCHEs). A detailed 3D computational model of the experimentally tested MCHEs was built and analyzed using the commercial software CFD-ACE® for the same experimentally tested operating conditions. The computational model results are in good agreement with experimental data of tested MCHE within +2% to +7% and ~0% to -13.5% variation for cold and hot fluids for the entire set of design of experiments (DoEs). This percentage disagreement may be due to various factors, such as manufacturing deviation within tolerance, longitudinal conduction, variation in the thermal conductivity of the material after heat treatment, variation in environmental temperature, sensor deviation, and surface roughness of internal channels. Instead of Stainless steel (SST), AlSi10Mg was used because of its lower manufacturing cost because AlSi10Mg was lighter than SST, though its thermal conductivity is almost ~8-10 times more than that of SST. A higher thermal conductivity is not good for MCHEs because it leads to higher longitudinal conduction, which eventually degrades the performance of MCHEs in terms of effectiveness. MCHE effectiveness is also reduced by ~12% to 18% owing to longitudinal conduction from ideal effectiveness.

Experimental investigation of pressure drop oscillation and active mitigation in a pumped two-phase loop

A pumped two-phase loop (P2PL) integrated with a microchannel evaporator is the most favored design for advanced thermal management of modern electronic devices. However, these systems are susceptible to two-phase flow instabilities, in particular pressure drop oscillation (PDO), which can compromise their performance by premature initiation of critical heat flux (CHF), deterioration of the heat transfer capabilities, and inducing severe thermal and pressure fluctuations. This study experimentally investigates PDO in a P2PL with a microchannel evaporator, exploring the underlying mechanisms and mitigation strategies. The range of parameters are: heat flux from 0 to 56 W/cm2, mass flux from 47.9 to 95.9 kg/m2-s, a fixed inlet temperature of 10 °C, initial accumulator gas pressure from 620.5 to 827.3 kPa, and vapor quality from zero (subcooled liquid) to one (pure vapor close to dryout). A consistent trend of high-amplitude, low-frequency PDO at low heat fluxes transitioning to low-amplitude, high-frequency PDO at high heat fluxes was observed across all operating conditions. PDO originating in the evaporator propagated to other loop components with similar characteristics, underscoring the systemic nature of PDO. Further, PDO-driven thermal oscillations were observed to propagate through the evaporator, reaching the heater (heat source) temperature with maximum amplitude of 3.4 °C. These oscillations had a detrimental impact on the heat transfer coefficient by altering the flow boiling regimes within the microchannels. Notably, the subcooled liquid temperatures remained stable, indicating the absence of pressure-induced thermal effects in single-phase regions. Finally, an active control technique, based on controlling the pump flow rate using continuous feedback of flow rate was implemented to mitigate PDO, eliminating both pressure and temperature oscillations, achieving an average reduction of 69.8 % in PDO amplitude.

Entropy generation and thermal behavior of microchannel fitted with punched curved vortex generators

Utilizing curved vortex generators (VGs) has emerged as a promising way to improve heat transfer in heat exchangers. However, research on the placement of punched rectangular curved winglet VGs on two opposing heat transfer surfaces of microchannel heat exchangers is limited. Through experiments and simulations, the effects of five perforation positions and three pitches on fluid flow and heat transfer were examined. This analysis is performed in the turbulent flow regime (2500 < Re < 3500) and the governing equations are solved by using SST k-ω model, assuming that the fluid is incompressible, has constant thermal properties, and ignores the effects of thermal radiation and gravity. Metrics such as the Nusselt number ratio, friction coefficient ratio, secondary flow intensity, thermal enhancement factor, and entropy generation are used to analyze the flow dynamics of mixed vortices. The results indicate that different perforation positions significantly affect the vortex characteristics, altering heat transfer and pressure loss. Furthermore, the pitch of the VGs plays a crucial role in governing heat transfer and frictional losses. Specifically, the heat transfer rate increased by 12.1 % to 61.1 % compared to empty tubes, accompanied by a rise in pressure loss ranging from 50.6 % to 115.1 %. To validate the findings, the principle of entropy generation was utilized. Notably, under conditions of a Re of 2500, a perforation position proximal to the VG's leading edge (θ = +12°), and a pitch of 15 mm, a remarkable thermal enhancement factor of 1.29 was achieved.

Influence of Rectangular Micro Inserts and Micro Chambers Heat Transfer Characteristics of Microchannel Heat Exchanger

This decade's smaller gadgets have made heat removal in electronics and microprocessors increasingly crucial necessitating the use of micro channel heat exchangers (MCHEs). The current study investigates the MCHE performance improvement through micro chambers and rectangular inserts with varying orientations (angle of insert: 0˚, 45˚, and 90˚). Experimental and numerical studies are conducted in a laminar environment, with Reynolds number varying from 74 to 446. Simulation of fluid flow and heat transfer is accomplished through Finite Volume Method. Thermal performance indicators, fluid flow parameters, pressure drop, friction factor, are used to evaluate and quantify the efficiency of MCHEs. It is shown that inserting two rectangles at 90° angle can achieve the ideal heat transfer coefficient. As a result, compared to the MCHE-MCDCI with various orientations of 0°, 45°, and 90°, respectively, the increase in Nu is 12.21%, 23.42%, and 37.10%, respectively. The rectangular insert at an angle of 90 in an MCHE caused the highest pressure loss. In contrast with MCHE-MCDCI. The pressure drop at 0˚, 45˚, and 90˚ increases by 13.26%, 37.94%, and 52.70%, respectively. When compared with double cylindrical inserts, MCHEs with rectangular inserts that are orientated at an angle of 90 degrees produced the greatest PEC.

Thin-film evaporation in microchannels: A combined analytical and computational fluid dynamics approach to assessing meniscus curvature impact

Computational fluid dynamics (CFD) is employed to investigate the effects of variation in bulk meniscus curvature on evaporative heat and mass transfer in microchannels. Evaporation in microchannels presents a classic multiscale problem, encompassing both microscopic and macroscopic length scales in the thin-film and bulk meniscus regions, respectively. Therefore, the liquid-vapor interface or meniscus shape is first determined through thin-film evaporation analysis using numerical approaches found in the literature. However, a new approach for establishing boundary conditions is also proposed, allowing for the representation of varying curvatures within the bulk meniscus region. Then, the obtained meniscus thickness profiles are exported to a two-dimensional CFD framework. The primary advantage of this developed CFD framework lies in its capability to simultaneously analyze evaporative heat and mass transfer from both microscopic and macroscopic regions, a feature that enhances research endeavors concerning micro and miniature heat pipes. The developed model is applied to various rectangular microchannel sizes, ranging from 10 to 100 μm in width, with wall superheats varying from 0.1 to 3.0 K. The aim is to quantify the effects of variations in bulk meniscus curvature on the evaporative characteristics of the extended meniscus (comprising both thin-film and bulk meniscus regions), using the concept of thermal resistance. Consequently, based on the CFD simulation results, multiple regression analysis is employed to formulate the total thermal resistance in terms of independent parameters, namely the microchannel width, wall superheat, and the radius of curvature (Rc). It is observed that the radius of curvature has a marginal impact on the total thermal resistance, allowing its influence to be expressed by a power-law function of (Rc/Rm)0.102, where Rm represents the minimum radius of curvature.

A micro-channel cooling system with two-phase looped thermosyphon for a supercritical CO2 Brayton cycle

The supercritical Carbon Dioxide (sCO2) closed Brayton cycle is a promising power generation technology, while the efficient cooling of CO2 and precise control of Compressor Inlet Temperature (CIT) is crucial for the high cycle efficiency and stable compressor operation due to the acute variation of thermophysical properties in the near-critical region. In conventional indirect cooling scheme, an intermediate single-phase water circuit is used to transfer heat from CO2 to water at the precooler, and then from water to the environment at the cooling tower, having the disadvantage of large pumping work consumption and high thermal resistance. In this work, a self-driven two-phase looped thermosyphon that significantly enhances the heat transfer by internal evaporation and condensation, is proposed to replace the water circuit. An experimental ultra-compact cooling system, consisting of a looped thermosyphon combined with micro-channel evaporator and condenser, filled with R134a coolant, is designed, fabricated, and tested. Visualized observation of the two-phase flow pattern and simultaneous measurement of the temperature, pressure and mass flow rates are conducted. A nodal analysis method is adopted, and a MATLAB code is developed for analyzing the internal fluid flow and the coupled sCO2-R134a-Air heat transfer, which is validated by experiment data. The results show that, the CO2 temperature could be accurately maintained at a specified near-critical point with a fluctuation of less than 1 K, and the average heat-releasing temperature can be reduced, while considerable pumping work, usually accounting for 2–5 % of the rated power output can be saved, thus contributing to increased cycle efficiency and system compactness.

A method to calculate the two-phase distribution in a microchannel heat exchanger

Maldistribution seriously impacts the heat transfer performance of the microchannel heat exchanger (MCHX). Fully understanding the two-phase distribution in the heat exchanger is important for advancing academic research and engineering applications. This study introduces a novel method for quantifying two-phase distribution in a microchannel heat exchanger. An experimental setup was developed to measure the local vapor mass fraction in the heat exchanger header. Capacitance signals were measured under inlet vapor mass fractions from 0 to 1, and inlet flow rates of 10, 15, and 25 g s−1 corresponding to a mass flux of 17.47, 26.2, and 43.66 kg m−2s−1, respectively. The local vapor mass fraction in the header was estimated using the capacitance measurements. The mass flow rate in the header, the microchannel tube, and the vapor mass fraction in the tube were calculated using the proposed model. The calculation model was validated against literature data, and the results were analyzed. The analysis reveals the characteristics of vapor mass fraction and mass flow rate distribution in the MCHX and further elaborates on the effects of phase separation, entrainment ratio, and pressure drop balance on the distribution. The proposed method can evaluate distribution in the header and tubes of microchannel heat exchangers, and it is also applicable to other types of two-phase flow devices.

Investigation of the insoluble impurities' impact on flow boiling heat transfer in aluminum microchannel heat exchangers

Microchannel flat-tube heat exchangers are known for their high heat transfer efficiency and compact size. In practical applications, the predominantly adverse influence of insoluble impurities on the condensation process necessitates further exploration into the underlying mechanisms affecting the flow boiling process. The effect of common insoluble impurities on the flow boiling of R410A refrigerant in a microchannel flat-tube heat exchanger has been investigated, and variation of the impurity volume fraction on heat transfer, mass transfer, pressure drop, and bubble formation are analyzed. Additionally, an adaptive modification method for the mass transfer factor is proposed. The numerical model of flow boiling heat transfer in a microchannel is validated through experimental data and empirical correlations. Thermo-hydraulic performance evaluation incorporates efficiency index and area goodness ratio metrics. Results reveal that the presence of insoluble impurities complicates the boiling heat transfer mechanism by influencing bubble evolution and multiphase flow patterns. Air impurities at a volume fraction not exceeding 5% prove beneficial for enhancing flow boiling efficiency in microchannels; however, a 38.5% decrease in efficiency index is observed with 1% oil impurities present. Optimal thermo-hydraulic performance is achieved with approximately 2%–3% water impurities.

Analysis of Heat Exchanger for Single-Phase Cooling Applications using Micro-channels of Copper Material

The design of a microchannel heat exchanger can be achieved using various approaches. The design includes various materials, such as ceramics, silicon, metals, and polymers, that are used to make microchannels, depending on their specific requirements. Polymers such as silicon, glass, and other polymeric materials are utilized on metallic substrates. The current study includes microchannels fabricated from metallic copper. Further, the design solutions do not consider the implications of the second law of thermodynamics. Hence, performing an energetic analysis of microchannels is imperative to design and assess thermodynamic systems that use them efficiently. One technique to improve a thermodynamic system's efficiency is using a well-designed microchannel heat exchanger with excellent energetic performance. This can be achieved by creating a thermodynamic system that eliminates energetic losses and limits only unavoidable losses. The use of high-conductivity material like copper also achieves this. To identify possible reasons for exergy loss and perhaps address them, a thorough energetic analysis of an existing heat exchanger is necessary. A microchannel heat exchanger with 19 microchannels in a flat tube is considered for this study. The study finds the energetic losses, which are useful for the thermal design of the heat exchanger.

Numerical simulation of heat transfer phenomena in a microchannel evaporator for a transcritical CO2 air conditioning system

This study presented a numerical simulation of heat transfer characteristics in a microchannel evaporator for a transcritical CO2 air conditioning system, and the simulated results have been validated by the experimental data. The evaporator consists of 6 passes with 29 flat tubes. Each flat tube has 10 microchannels having a 1.2 × 0.6 mm cross-section. The two-phase flow was simulated in the range of evaporation temperatures from 5 to 15 °C; the mass flow rates of 24.16, 30, and 34.96 g/s; and inlet vapor qualities of 0.5, 0.61, and 0.75, respectively. The results show that the two-phase flow with the evaporative temperature at the inlet of 5, 10, and 15 °C became superheated at the 3rd, the 4th, and the 5th pass, respectively. At the evaporation temperature of 15 °C, the heat transfer coefficient decreases from 8.1 to 3.6 kW/m2 K as the vapor quality increases from 0.75 to 1. With the mass flow rate of 30 g/s, in the tube length range from 0 to 1.1 m, the heat flux achieved around 1.55 kW/m2. The numerical cooling capacity gets the maximum value of 2.85 kW at the evaporative temperature of 10 °C. The numerical results are in good agreement with those obtained from the experimental results and the other published results, with a deviation of less than 10%.

An experimental investigation on frosting characteristics and performance of microchannel evaporators with varied aspect ratios

Microchannel evaporators are susceptible to frosting, which can significantly impair heat transfer performance. To provide a basis for microchannel evaporators' effective design and broad application, frosting experiments were conducted in this study. Leveraging infrared thermal imaging and digital image processing technology, the impact of different aspect ratios on refrigerant distribution was quantitatively measured, and the microchannel evaporators' frosting behavior and performance under frosting conditions were analyzed. The results showed that a higher aspect ratio for Evaporator C led to reduced uniformity in the refrigerant distribution, resulting in an increased frost height, a larger frosting coverage area, and greater frost accumulation. Consequently, as frost accumulated, Evaporator C exhibited the most discernible reductions in the heat transfer rate, evaporation pressure, and refrigerant pressure loss, which were 61.07 %, 31.7 %, and 52.83 %, respectively. Therefore, microchannel evaporators with small aspect ratios are recommended where practical field installation conditions permit. And the results are anticipated to provide useful guidance for selecting microchannel evaporators with the optimal aspect ratio, tailored to operate efficiently under frosting conditions.

Experimental study on a direct-expansion micro-channel PV/T evaporator using water-ZnO nanofluid as the spectral beam splitter

Introducing nanofluid (NF) as the spectral beam splitter (SBS) in photovoltaic/thermal (PV/T) evaporators can significantly enhance their performance and energy flexibility. In this study, a novel direct-expansion micro-channel evaporator using water-ZnO nanofluid as SBS (i.e., NF-MC-PV/T evaporator) was manufactured. Particularly, the stability of low-viscosity water-ZnO nanofluid was first optimized and natural convection within the NF-MC-PV/T evaporator was directly formed. Further, a direct-expansion heat pump system based on the NF-MC-PV/T evaporator was developed and tested. According to the findings, adding sodium hexametaphosphate as a dispersant with the dispersion ratio of 1:5 and ultrasonic treatment for 1.5 h can achieve the optimal stability of water-ZnO nanofluid. The nanofluid's natural convection can reduce the evaporator's operating temperature and improve the PV module's temperature distribution uniformity. Specifically, the NF-MC-PV/T evaporator's operating temperature was lower than the environment temperature and a pure PV module. Besides, the PV module's temperature distribution was uniform in the direction perpendicular to the refrigerant flow with a max temperature gradient of only 4.59 °C. The typical photothermal efficiency of the NF-MC-PV/T evaporator reached 102.55 % while the heat loss coefficient was only 4.37. Moreover, the average photothermal efficiency, photovoltaic efficiency, and COP of the system were 103.58 %, 12.03 %, and 5.09, respectively.

Study of impact of nano fluids on performance of microchannel heat exchangers using CFD

Addressing the critical issue of heat generation in electronic devices due to miniaturization and higher power density is essential. As electronic components become more compact, they generate more heat flux, necessitating efficient thermal management solutions. Traditional methods and fluids, such as water, struggle to meet the demand for efficient heat dissipation. To address this challenge, the utilization of nanofluids presents a promising solution. The objective of this study is to use CFD methods to examine how a nanofluid can improve heat transmission and lower the maximum temperature in a microchannel heatsink. This article presents the study of microchannel heatsinks with two distinct channel counts (five and eight). A constant flow, incompressible, laminar model was used to verify the findings. The working fluids used in the study were water in various concentrations, water-based nanofluids of Fe3O4-water and MWCNTs. CFD simulations revealed that a MWCNT-water nanofluid at 0.2 % concentration significantly improved cooling performance compared to water, demonstrating the potential of nanofluids for efficient thermal management in electronic devices.

Transient refrigerant distribution in a microchannel heat exchanger heat pump system under different reverse cycle defrosting strategies

The migration and redistribution of refrigerant are critical factors that affect the refrigeration system performance. To improve the defrosting and start-up heating performance, it is essential to investigate the transient distribution characteristics of refrigerant mass. However, quantitative studies on the transient distribution of refrigerant during defrosting and start-up heating stages in heat pump systems are scarce. The dynamic characteristics of defrosting and start-up heating cannot be deeply understood from the perspective of refrigerant migration. Therefore, the purpose of this paper is to experimentally study the transient distribution characteristics of refrigerants during defrosting and start-up heating stages for different defrosting strategies. Based on the refrigerant-side dynamic characteristics, the defrosting cycle is divided into three stages for the defrosting strategy with the indoor fan off, the indoor coil charging stage, accumulator charging stage, and wet compression stage. Additionally, for the defrosting strategy with the indoor fan on, it is divided into two stages: the indoor coil charging stage and the outdoor coil discharging stage. For the defrosting strategy with the indoor fan off, the wet compression phenomenon occurs at 240 s, which poses significant challenges to the stability of the compressor. At the end of defrosting, the accumulator retains the most refrigerant for both defrosting strategies. From the perspective of refrigerant transient distribution, the start-up heating stage is the process of refrigerant migration from the accumulator to indoor and outdoor coils. The two main factors that affect start-up heating performance are heating the indoor coil metal, and vaporizing the liquid refrigerant in the accumulator. For the defrosting strategy with indoor fan on, the energy consumption of heating the indoor coil and vaporizing the liquid refrigerant is reduced by 45.7 % and 48.9 % during start-up heating. Based on the transient refrigerant distribution experiment, some methods to improve defrosting and start-up heating are also proposed. This study can provide useful insights into the transient distribution of refrigerants and provide guidance for defrosting optimization.

On the analysis of static thermal instabilities occurring in two-phase flow systems

In this study, we investigate a novel type of static thermal instability that occurs in two-phase flow systems. The instability is theoretically and experimentally confirmed to occur for flow boiling micro-channel scenarios and flow condensing scenarios. The theory presented is independent of the evaporator geometry as well as flow boiling/condensing situations. A stability criteria is derived using a Reynolds Transport approach applied to the evaporator of a two-phase pumped loop (TPPL) system. The theory is then validated experimentally using a TPPL containing a parallel micro-channel evaporator. The instability is confirmed with pressure, temperature, and void fraction measurements acquired at the exit of the evaporator. The findings reveal that static thermal instabilities can arise when simultaneous heat addition and reduction in system saturation temperature occurs (or vice versa). The implications of the thermal instability result in dramatic changes in evaporator heat flux, as well as a flow transition from stratified laminar flow to vigorous turbulent flow with high void fractions. By identifying the additional instability mechanisms, this work contributes to enhancing system reliability and predictability of TPPL systems.

Role of physical structure on performance index of crossflow microchannel heat exchanger with regression analysis

Microchannel heat exchangers have become the preferred choice in contemporary technologies like electronics, refrigeration, and thermal management systems. Their popularity stems from their compact design and exceptional efficiency, which outperform traditional heat exchangers (HE). Despite ongoing efforts, the optimal microchannels for enhancing heat management, minimizing pressure drop, and boosting overall performance have yet to be identified. This study seeks to deepen our understanding of heat transmission and fluid dynamics within a cross-flow microchannel heat exchanger (CFMCHE). Utilizing numerical modeling, it examines how various physical aspects—such as channel geometry, spacing between channels, the number of channels, and the velocity at the inlet—affect key performance indicators like pressure drop, effectiveness, Nusselt number, and overall efficiency. To enhance the design, we analyze six unique shapes of crossflow microchannel heat exchangers: circular, hexagonal, trapezoidal, square, triangular, and rectangular. We employ the Galerkin-developed weighted residual finite element method to numerically address the governing three-dimensional conjugate partial differential coupled equations. The numerical results for each shape are presented, focusing on the surface temperature, pressure drop, and temperature contours. Additionally, calculations include the efficacy, the heat transfer rate in relation to pumping power, and the overall performance index. The findings reveal that while circular shapes achieve the highest heat transfer rates, they underperform compared to square-shaped CFMCHEs. This underperformance is largely due to the increased pressure drop in circular channels, which also exhibit a 1.03% greater reduction in effectiveness rate than their square-shaped counterparts. Consequently, square-shaped channels, boasting a performance index growth rate of 53.57%, emerge as the most effective design among the six shapes evaluated. Additionally, for the square-shaped CFMCHE, we include residual error plots and present a multiple-variable linear regression equation that boasts a correlation coefficient of 0.8026.

Numerical investigation for the effects of surface roughness in counter flow microchannel heat exchanger with different channels geometries

This article presents a numerical investigation focused on how roughness of surface affects the overall performance of a counter-flow microchannel heat exchanger (CFMCHE). The study examines various microchannel shapes, including triangles, squares, circles, and trapezoids, to evaluate their performance within the context of CFMCHE. Water with consistent properties flows through aluminum microchannels used as the working fluid. The analysis employs the roughness-viscosity method to assess how surface roughness influences the CFMCHE’s performance. The study’s findings emphasize that the trapezoidal channel shape exhibits the most favorable performance among the shapes investigated. Additionally, among the operational parameters considered, the hydraulic diameter emerges as the most influential factor in determining the most suitable characteristics for CFMCHE. The presence of surface roughness was found to marginally improve thermal performance while slightly reducing hydraulic efficiency. This research provides valuable insights into the intricate interplay between surface roughness and channel shape. Notably, the impact of roughness is more pronounced in the case of the trapezoidal shape compared to other geometries.

Study on the Flow and Heat Transfer Performance of Microchannel Heat Exchangers With Different Elliptical Concave Cavities

AbstractEllipticity has a significant impact on the flow and heat transfer performance of microchannel heat exchangers (MHEs) with elliptical concave cavities. In this study, five types of MHEs with different elliptical concave cavities (ellipticities of 0.4, 0.6, 0.8, 1.0, and 1.2) were designed. The influence of ellipticity on the flow and heat transfer performance of MHEs was numerically investigated using ANSYS Fluent 21.0 R1. Moreover, MHEs with corresponding elliptical concave cavities structures were processed and manufactured, and then an experimental platform was designed and built for experimental verification. The results showed that the fluid velocity distribution in MHEs with elliptical concave cavities was symmetrical, and the formation of secondary flow in the elliptical concave cavities led to the continuous destruction and reconstruction of the flow and thermal boundary layer in the microchannel, which is conducive to mass and heat transfer in the MHEs with elliptical concave cavities. The inlet and outlet pressure drop of MHEs with elliptical concave cavities increased as the inlet flow rate increased. At the same inlet flow rate, the inlet and outlet pressure drop of the MHE with elliptical concave cavities first increased and then decreased with increasing ellipticity. At an ellipticity of 1.0, the inlet and outlet of MHE exhibited the lowest pressure drop indicating that the MHE with an ellipticity of 1.0 featured the highest pressure drop performance. The cold‐water outlet temperature of the MHEs with elliptical concave cavities first decreased and then increased as the inlet flow rate increased. At the same inlet flow rate, the cold‐water outlet temperature of the MHEs with elliptical concave cavities first increased and then decreased with increasing ellipticity, while the hot‐water outlet temperature of the MHEs first decreased and then increased with increasing flow rate. This indicated that the MHE with an ellipticity of 1.0 exhibited excellent heat transfer performance.

Investigation on the performance of a novel heat transfer structure based on a new twisted airfoil fin array

Printed circuit heat exchanger (PCHE) is a type of micro-channel heat exchanger with high performance, which has a broad application in microelectronics, solar energy, and aerospace. Airfoil fins are widely recognized due to their exceptional thermo-hydraulic performance, but there are few studies on their shape adjustment in three dimensions. In this study, a novel twisted airfoil fin was proposed and applied to the heat exchanger. The heat transfer and flow resistance of the twisted airfoil fin PCHE with the traditional PCHE are compared using the numerical simulation method, and the influence of the twist angle, fin spacing, and arrangement is investigated. The results show that the new fins have excellent flow and heat transfer performance. Under the multiple Re number conditions, the Nu number is improved up to 52%, and the performance evaluation criteria is increased up to 16%. Also, increasing the twist angle of the fins, decreasing the fin spacing, and staggering the fins according to diverse twist directions can improve the performance of the heat exchanger.