Excellent Heat Transfer Performance Research Articles

Effect of annulus ratio on the residence time distribution and Péclet number in micro/milli‐scale reactors

AbstractMicro/milli‐scale annular reactor with straight and helical forms has excellent heat and mass transfer performance due to the short molecular diffusion distance and dual‐wall surface transport. The annular gap spacing is scalable by adjusting the inner and outer tube diameter. The influence of diffusion and convection effects on axial dispersion as expanding the flow scale requires further elucidation with the help of residence time distribution (RTD) curves and Péclet (Pe) numbers. The correlation of RTD characteristics with annulus ratio γ = Dh/D (ratio of annulus characteristic size to outer diameter) is investigated using computational fluid dynamics. Results show that with enlarging the straight annular gap from micro‐scale to milli‐scale, RTD characteristics exhibit opposing patterns. This can be attributed to the transition from diffusion‐dominated to convection‐dominated on momentum transfer, and the transition interval is 0.167 < γ < 0.250. Correlation equations of Pe number with Reynolds (Re) number and γ are established under diffusion‐dominated and convection‐dominated states. The symmetrically distributed secondary flow in the helical annular gap effectively elevates the Pe (Pemax > 100). Correlation equations of Pe with Re and γ are established in helical annular gaps with 0.083 < γ < 0.208 and 0.167 < γ < 0.500. The above results contribute to understanding the annular flow RTD characteristics for better applications of tube‐in‐tube reactors.

Enhancement of Thermal Management Performance of Copper Foil Using Additive-Free Graphene Coating.

Advanced thermal interface materials with high thermal conductivity are crucial for addressing the heat dissipation issue in high-power, highly integrated electronic devices. One great potential way in this field is to take advantage of cooling copper foil (Cu) materials based on graphene (G). However, the current manufacturing of these cooling copper foil materials is accompanied by high cost, process complexity, and environmental problems, which limit their development and application. In this work, a simple, low-cost, environmentally friendly graphene-copper foil composite film (rGO/G-Cu) with high thermal conductivity was successfully prepared using graphene oxide directly as a dispersant and binder of graphene coating. The microstructure characterization, thermal conductivity and thermal management performance tests were carried out on the composite films. The results demonstrate that compared to pure copper foil (342.47 W·m-1·K-1) and 10% PVA/G-Cu (367.98 W·m-1·K-1) with polyvinyl alcohol as a binder, 10% rGO/G-Cu exhibits better thermal conductivity (414.56 W·m-1·K-1). The introduction of two-dimensional graphene oxide effectively enhances the adhesion between the coating and the copper foil while greatly improving its thermal conductivity. Furthermore, experimental results indicate that rGO/G-Cu exhibits excellent heat transfer performance and flexibility. This work is highly relevant to the development of economical and environmentally friendly materials with high thermal conductivity to meet the increasing demand for heat dissipation.

High-efficiency thermal-electric conversion enabled by water-solid triboelectric nanogenerators within a 3D pulsating heat pipe

At present, effective strategies for obtaining electric energy from harvesting and converting thermal energy have attracted great attention in the field of new energy. According to the working principle of electrostatic induction and triboelectrification, the triboelectric nanogenerators (TENGs) technology is regarded as a promising energy harvester. Herein, we propose a novel thermal-electric generator that combines a liquid-solid TENG and a 3D pulsating heat pipe (3D-PHP). The liquid-solid TENG consists of copper foil and polytetrafluoroethylene (PTFE) tubes, and 50 % deionized water is filled into the 3D-PHP. Based on phase change heat transfer, water columns in the 3D-PHP will pulsate and flow through a liquid-solid TENG, leading to the generation of electric energy. The minimum thermal resistance of this 3D-PHP with TENGs is only 0.131 K/W at a heating power of 200 W, indicating it has excellent heat transfer performance. The peak output voltage and power generated by the developed 3D-PHP generator are up to 14 V and 1.05 μW, respectively. Finally, the harvested electricity is successfully applied to power a digital thermometer. These findings will offer a promising strategy for harvesting thermal energy from electronic equipment and systems involving high-flux heat production and dissipation.

The heat transfer enhancement mechanism of W-shaped micro-ribs on impingement cooling

In order to improve the performance of impingement cooling in turbine blades, W-shaped micro-ribs are arranged on the target surface to weaken the influence of cross-flow and generate longitudinal vortexes. The k-ω SST turbulence model is used for numerical simulation, and the mechanism of W-ribs on the enhancement of air impingement cooling performance and the influence of W-ribs geometry are studied. Under the condition of jet flow Reynolds number 4000 to 10000, based on the W-ribs with an angle α = 120°, width W = 0.1 mm and height H = 0.3 mm, the effects of angle (α = 90°, 120°, 150°, 180°), width (W = 0.05, 0.1, 0.2, 0.4 mm) and height (H = 1, 3, 4, 8 mm) on flow and heat transfer are investigated respectively. The results show that the W-ribs can separate the flow to both sides while generating longitudinal vortexes, which can reduce the influence of crossflow and enhance the sweep of the target surface to achieve the effect of enhancing heat transfer. α is the key factor affecting the generation of longitudinal vortex. W has little effect on the flow structure, but mainly affects the vorticity. H mainly affects the distribution of mass flow rate, which has a direct impact on the uniformity of upstream and downstream heat transfer. The W-ribs with α = 120°, W = 0.1 mm and H = 0.4 mm is recommended because of its excellent heat transfer performance and high comprehensive heat transfer performance, which are 39.7–48.9 % and 1.5–9.7 % higher than the smooth target surface, respectively.

The efficient synthesis of Pregabalin with impurity control using a continuous flow system

This article developed a microreactor system for the continuous synthesis of Pregabalin. Due to the exceptional heat transfer and mixing capabilities exhibited by the system at the microscale, the Hofmann rearrangement reaction, traditionally requiring multiple sequential steps in batch reactors, can now be efficiently achieved in a consolidated single-step microreactor process. The reaction was executed at a comparatively elevated temperature range of 40–50 °C, and took 5–6 min to achieve the yield of over 90 %, which was a significant improvement compared to the conventional batch reactor method, requiring 7–8 h with a yield of 83 %. The microreactor system utilized its excellent mass and heat transfer performance to reduce the level of the key impurity to below 0.15 % at higher reaction temperatures, meeting the quality requirements for pharmaceutical production. Through experimental research, we determined the effects of reaction conditions like concentration, temperature, and residence time on the reaction rate, as well as key trace impurities.

Bubby behavior and heat transfer characteristics of bionic microchannels in the subcooled flow boiling process

Microstructures on the sidewall or bottom wall, have shown excellent heat transfer performance in the single-phase convective heat transfer of microchannel heat sinks. For increasing the heat flux, phase-change heat transfer was highlighted as an effective approach. However, more complicated mechanisms of boiling heat transfer make less study focused on the microchannel with microstructure. In this work, a bionic microchannel with concave cavities and bionic ribs was proposed to enhance the boiling heat transfer. Numerical simulations, along with the volume of fluid (VOF) analysis combined with a phase-change model, were used to investigate the effect of the microstructure on the behavior of bubbles in the subcooled flow boiling. The results showed that the microstructure promotes bubble nucleation and the occurrence of more small bubbles around big bubbles. Thus, it enhances boiling heat transfer. Meanwhile, the microstructure was found to be beneficial in maintaining a stable liquid film evaporation under annular flow and suppressing boiling instability. Ultimately, compared with rectangular microchannels, the reported wall temperature and inlet pressure are more stable in the proposed bionic microchannel, the heat transfer coefficient and critical heat flux of the bionic microchannel were found to be 1.45 times higher, with mass flux G of 498 kg/(m2·s) and heat flux q w of 600 kW/m2.

Visualized-experimental assessment on a two-phase thermosyphon loop downcomer state with wide range of filling ratios

The two-phase thermosyphon loop (TPTL), which has an excellent heat transfer performance with simple, compact structure and pump-free advantages, can effectively solve the heat transfer problem under high heat flux. It is necessary to optimize the TPTL to operate in good conditions, especially the state of the downcomer in which the liquid head is one of the critical parameters to determine the driving force of the circulation. However, in the existing studies, the flow features under high filling ratio and high heat flux were ignored in the downcomer. Since a high filling ratio has been proved to have good performance at high heat flux. Herein, the flow characteristics of the TPTL downcomer were seen and quantified using an experimental visual setup under different filling ratios in this study. Two flow features under high heat flux, for the first time, are reported: 1. two-phase flow in the downcomer at high filling ratios. 2. liquid column height oscillation under a partially liquid-filled state. According to the results, the filling ratio significantly impacts the flow characteristics of the downcomer. The TPTL downcomer state, contrary to the traditional understanding, can be partially filled with liquid but not totally filled with fluid all the time, implying that the driving force may be less than the typical assumption. TPTL with a high filling ratio can also provide a maximum gravity pressure head driving force due to the full downcomer. In addition, the bubble pump, which influences by the heat flux, also accelerates the mass flow in the TPTL. Consequently, TPTLs with a high filling ratio showed a significant thermal performance. A partially filled with the liquid phenomenon is demonstrated in moderate filling ratios, and the height of the liquid column will change as the heat flux increases, which indicates the self-regulation of TPTL. When the filling ratio is low, the liquid column height is greatly influenced by the filling ratio. The high liquid column will also give the TPTL excellent thermal performance. The ideal state of a TPTL downcomer is the downcomer filled with two-phase liquid under a high void fraction, which is realized by a high filling ratio TPTL. This paper sheds some light on the downcomer state of TPTLs to optimize the TPTL thermal performance.

Experimental investigation on the heat transfer performance of Galinstan liquid metal driven by electromagnetism

Liquid metals have excellent heat transfer performance and unique electromagnetic characteristics, providing new visions for cooling the high speed motorized spindle shaft. Liquid metal can be driven by the magnetic field of the motor stator to induce current with no dynamic seal problem. In the present study, a shaft cooling structure of a motorized spindle with Galinstan liquid metal as the working fluid was designed and the heat transfer performance of the designed structure was investigated experimentally. The obtained results at the rated speed and rated current show that the induced voltage in the wire installed on the shaft reaches 1.2 V, which can circulate the liquid metal in an 8 mm diameter copper pipe. In this case, its equivalent thermal conductivity reaches 8.1?104 W/m ?C, which can effectively reduce the temperature of the motorized spindle rotor and make the temperature distribution of the motorized spindle more uniform.

Anti-icing system based on multi-level micro-nano and electric heating dual structure

The potential application value of superhydrophobic surfaces with anti-icing and de-icing properties in aerospace, telecommunications cables, energy and other fields has always been an important research topic. In this paper, a kind of superhydrophobic surface with stable structure, sufficient heat, excellent heat transfer performance and mass production was prepared based on elastic material. In this study, the multi-stage micro-nano rough structure is synthesized by ingenious pressing and mold closing control, and the surface contact angle of the prepared sample can reach 159°. The multi-stage micro-nano rough structure on the surface of the experimental sample can make the water droplets form a large number of cavitation, which can delay the icing of static water droplets. The height difference on both sides of (Un)pressed mesh surface makes the water droplets freeze asymmetrically, so (Un)pressed mesh surface has excellent anti-icing ability. The experimental sample is connected with 24 V direct current, and the average resistivity is 1.403 Ω·cm. The temperature can be raised to about 60 °C in one minute. The prepared sample has stable temperature, good electrical conductivity, sufficient heat generation, excellent heat transfer performance and high anti-icing efficiency. This study expands the design idea of anti-icing of aircraft rotor.

Direct ink writing of hierarchical porous SiC ceramics as catalyst support for hydrogen production

Due to the tunable porosity at multiple scales, hierarchical porous ceramics feature large specific surface area and excellent heat and mass transfer performance, which can effectively improve the catalytic reaction performance. This paper presents a method to fabricate SiC scaffolds with regular and hierarchical pore structures by direct ink writing (DIW) combined with sacrificial template technology, which can be used as methanol steam reforming (MSR) microreactor catalyst supports. Through printing along a defined path, primary pores with a regular pore structure were created. After sintering, the sacrificial template was removed and secondary pores appeared. Four different types of hierarchical porous SiC scaffolds were successfully prepared and the pore structure, total porosity, linear shrinkage and compressive strength of these scaffolds were investigated. The catalyst coating was then loaded onto the scaffold, and the microstructure characterization showed that the pore structure would not be damaged and blocked. Finally, the hydrogen production experiments were carried out on the MSR microreactor, and the results showed that the support with larger and denser secondary pores had the best fluid flow and hydrogen production characteristics. At the temperature of 280 °C and the gas hourly space velocity (GHSV) of 30000 ml g−1 h−1, the methanol conversion and hydrogen production of the best support can reach 90.95 % and 44.96 ml/min, respectively.

Thermohydraulic and thermal fatigue characteristics of W/Cu flat-type microchannel mock-up for CFETR divertor

The divertor of the China Fusion Engineering Test Reactor (CFETR) requires a more efficient heat dissipation structure due to the high demand of heat flux dissipation of up to 20 MW/m2. Microchannel cooling technology excels in thermal management because of large heat transfer area to volume ratio and capability to achieve uniform temperature distribution. However, the heat transfer and thermal fatigue characteristics of W/Cu flat type mock-up with microchannel cooling structures at a heat flux of 20 MW/m2 remains elusive. In this work, we analyzed the thermohydraulic (numerically) and thermal fatigue (experimentally) characteristics of W/Cu flat-type microchannel mock-up. The numerical results show that the thermal loaded area (W) of the microchannel mock-up possesses excellent temperature uniformity and heat transfer performance (the W surface temperature is only ∼685 °C even at a low volumetric flow rate V̇ = 5 L/min). We also compared the heat dissipation efficiency with the hypervapotron cooling channels, and found that the maximum temperature of the W surface and channel wall of the microchannel mock-up are reduced by 18.9 % and 46.7 %, respectively. The thermal stress analysis indicates that the maximum equivalent stress is concentrated in the middle region of the W surface at 15 s, with a value of 357.8 MPa that is below the maximum allowable stress of W material (425 MPa at 650 °C). The as-manufactured W/Cu flat-type microchannel mock-up successfully withstood a thermal fatigue test consisting of 1000 cycles at 20 MW/m2 steady state heat load at V̇ = 30 L/min and Tin = 25 °C. The maximum temperature of W is only 616.2 °C during the test, and some microcracks are detected on the W surface after the test; these microcracks are perpendicular to the heat loading surface, which have negligible influence to the heat transfer of the entire mock-up. This study reveals that the W/Cu flat-type microchannel mock-up is promising in dissipating ultra-high heat flux (steady-state 20 MW/m2) on the divertor target, which might provide valuable insights for the engineering design of the CFETR divertor.

Experimental Study on the Small Two-Phase Thermosyphon Loop With Minichannel Evaporator

Abstract This study experimentally investigates the small two-phase thermosyphon loop with a minichannel evaporator. The influences of heating power, fan power, and inclination angle on the heat transfer performance are presented, and the related mechanisms are revealed. Results show that the thermal resistance of the thermosyphon loop tends to decrease as the heating power is increased. It is found that there exists an optimal value of fan power. Interestingly, the invalidity behavior of thermosyphon under the inclination condition prefers to occur at higher heating power. To sum up, the small two-phase thermosyphon loop with a minichannel evaporator could produce excellent heat transfer performance with energy-saving characteristics, indicating its wide potential applications in the field of electronic chip cooling.

Experimental study on heat transfer performance of high temperature heat pipe under axial non-uniform heat flux

Non-uniform high-temperature large heat flux is commonly encountered in engineering applications, posing challenges to heat transfer processes and affecting system performance. High temperature heat pipes offer an effective solution to mitigate the adverse effects of non-uniform heat flux by leveraging the unique characteristics of their inner alkali metal (or alloy) working fluid, such as high latent heat of vaporization, strong heat flux density, and ability to operate at elevated temperatures. These features enable high temperature heat pipes to achieve excellent isothermal and uniform heat transfer performance, thereby improving overall thermal management in heat transfer systems. Building upon the investigation of the original high temperature heat pipe, this study designed and fabricated a specially shaped high temperature heat pipe with a spherical crown surface as the evaporator. Experimental research was conducted to assess its frozen start-up performance and heat transfer characteristics under the influence of axial non-uniform heat flux. The results were also analyzed theoretically, providing valuable insights into the frozen start-up performance and heat transfer performance of the high temperature heat pipe in the presence of non-uniform heat flux conditions. The analysis results reveal several important findings: (1)The high temperature heat pipe demonstrates its capability to convert axial non-uniform high-temperature large heat flux into a uniform heat flux, thus achieving excellent uniform heat transfer performance. (2)The theoretical solution obtained through the lumped heat capacity analysis method shows satisfactory agreement with the actual frozen start-up process of the high temperature heat pipe. This theoretical reference can aid in the transient analysis of the frozen start-up process under the influence of axial non-uniform high-temperature large heat flux. (3)The experiment investigated the influence of heating power on heat transfer performance and temperature uniformity. The results indicate that the temperature uniformity of the high temperature heat pipe exhibits a trend of initially increasing and then decreasing. Specifically, the best temperature uniformity is achieved when the heating power is 1084.7 W. Moreover, when the heating power is 1197.9 W, the high temperature heat pipe exhibits the lowest equivalent thermal resistance of 0.0265 K/W, indicating the best heat transfer performance. (4) The variable power heating approach demonstrates that increasing the heating power leads to an extension of the effective length of the heat pipe. The most favorable heat transfer performance and temperature uniformity are observed when the heating power is set to 1133.7 W, allowing the full length of the condenser of the high temperature heat pipe to participate actively in the heat transfer process. These results can provide quantitative experimental data and theoretical references for improving the thermal shock of non-uniform high-temperature large heat flux.

Investigation of the cooling and purification effect of automobile exhaust using heat pipe heat exchanger

Heat pipe heat exchangers (HPHEs) have excellent heat transfer performance and have been applied in many fields. However, the cooling and purification effects of the HPHE on the automobile exhaust are still not clearly acknowledged. In this paper, an HPHE applied to automobile exhaust cooling and purification was designed and developed. By establishing 3D physical model and mathematical model, the influences of heat pipe inclination angles and cooling air temperatures on the cooling effect of the automobile exhaust are studied. And the cooling and purification effects under different engine speeds have been studied experimentally by connecting the HPHE to a 1.8 T Volkswagen Passat car. The results indicate that when the dip angle is 30°, the heat exchanger has the best cooling effect. When the engine speed reaches 3000 rpm, the heat removed by the cooling air reaches a peak of 3.06 kW with the maximum cooling efficiency of 56.37 %. The HPHE has a certain purification effect on the SO2 and NOx in the automobile exhaust. The maximum purification rates are 15.4 % and 13.8 %, and the peak purification rates appear at 2000 rpm and 2500 rpm, respectively, while the purification effect on the CO is not obvious.

Research and Application of Steam Condensation Heat Transfer Model Containing Noncondensable Gas on a Wall Surface

Steam condensation plays an important role in various engineering processes due to its excellent heat transfer performance. However, condensation in the presence of noncondensable gas has attracted great attention in recent years since noncondensable gas will have a negative effect on condensation heat transfer. The present study proposes a comprehensive model coupled with convective heat transfer, liquid film heat transfer and steam condensation for the heat transfer of condensation with noncondensable gas and uses it in the Program Integrated for Severe Accident Analysis (PISAA) for a nuclear power plant. The condensation heat transfer model has good universality, the calculation process is stable with less iteration and a fast convergence and it is verified and validated by comparing the simulation results of the PISAA and those from traditional containment analysis codes, as well the experiments from the Wisconsin condensation tests; then, a sensitivity analysis for the parameters of the heat transfer coefficient is performed. The validation results show that the average error of the condensation heat transfer coefficient is approximately 10%, and the maximum error does not exceed 30%. The deviation from the experimental data is limited in the acceptable range, which could fulfill the requirement for the analysis of containment accidents in nuclear power plants.

Fabrication and thermal performance of a solar-driven heat pipe filled with reduced graphene oxide nanofluids

Nowadays, the solar-thermal technology, converting solar energy into useful thermal energy, was regarded as a direct and facile method to harvest solar irradiation for alleviating the energy crisis and environmental issues. In this work, we reported a transparent solar-driven heat pipe filled with rGO nanofluids, which combined volumetric solar-thermal harvesting and heat pipe technology to realize efficient solar capture while fast transporting of the collected thermal energy to the application ends simultaneously. The rGO nanofluids not only were used as solar volumetric absorbers to absorb solar radiation directly, but also completed the whole thermal cycle as the working fluid. We investigated the impact of filling ratio, inclination angle, working fluids, and solar power density on the thermal property of the heat pipe experimentally. It was found that 20% was the optimal filling ratio for the heat pipe with a lowest thermal resistance of 0.25 K/W at the solar power density of 17.5 W/cm2. Under the vertical operation mode, the heat transfer performance of the solar-driven heat pipe was better than that under the horizontal operation mode. Finally, this developed solar-driven heat pipe had been successfully applied for solar water heating systems, showing excellent heat transfer performance.

Experimental study on the parallel-flow heat pipe heat exchanger for energy saving in air conditioning

Energy saving significantly and positively affects energy conservation and releases less carbon dioxide. This study aims to investigate the energy-saving characteristics of a novel parallel-flow heat pipe heat exchanger (PFHP-HE) in air conditioning. It merged the characteristics of high axial heat transfer performance of heat pipe with high external heat transfer performance of parallel-flow heat exchanger (PF-HE). The test rig for the PFHP-HE was built on the basis of the heat transfer wind tunnel in this work. The heat transfer performance of parallel-flow heat pipe heat exchanger charged with R600A as the working fluid was experimentally studied. The filling rate of the heat pipe was 26%, and its thermal behavior was analyzed. The evaporation section of the PFHP-HE was heated by heating belt. The experiment was conducted with heating power of 500W. The experiments were performed with cooling air flow rates ranging from 63.36 m3/h to 118.08 m3/h. The results indicate that when the airflow rate was 118.08m3/h, the minimum thermal resistance of the PFHP-HE was 0.06 K/W, and the heat transfer efficiency was up to 98% in the experiments. As the pulsation phenomenon was caused by its small diameter, the temperature distribution in condenser had stratified phenomenon in PFHP-HE. The PFHP-HE has excellent heat transfer performance and working stability. The PFHP-HE is a promising heat exchanger for energy-saving in air conditioning. Its superior heat transfer performance and working stability make it an attractive alternative to conventional heat pipe heat exchangers.

Model test on thermo-mechanical properties of static drill rooted energy pile under long-term temperature cycles

Static drill rooted (SDR) pile emerges as a composite of a prefabricated pile and cemented soil. SDR pile technology was introduced into the energy pile design due to its high load-bearing capacity, excellent heat transfer performance and favorable stability. Indoor model tests were established to investigate the thermo-mechanical behavior of an SDR energy pile under long-term temperature cycles. It was found that the studied pile had better heat transfer performance and bearing capacity (50%) than the ordinary pile. After twenty long-term temperature cycles, Additional tensile and compressive stress were observed in the pile. The additional thermal stress in the pile initially increased and then decreased with the increasing depth of the pile. The stress fluctuation would not damage the pile material since it was maintained within the design value of concrete strength. The side friction of the pile gradually increased with the increasing cycle numbers. The cumulative settlement of the SDR energy pile was induced by temperature cycles and reached −0.155 mm (0.18% D) after 20 cycles, less than the ordinary pile. The first two cycles accounted for 53% of the total cumulative settlement, and cooling was the main factor causing pile top settlement. The ultimate bearing capacity of the SDR energy pile was decreased by 9% after 20 cycles. The investigation of the long-term thermo-mechanical behavior of the SDR energy pile provides a theoretical basis for its practical application. SDR energy piles are significant for the efficient use of shallow geothermal energy.

Ammonia decomposition over Ru-coated metal-structured catalysts for COx-free hydrogen production

We report the development of Ru/Mg–Al oxide coated metal-structured catalysts with excellent heat and mass transfer characteristics for efficient clean H2 production from ammonia decomposition. Ammonia is a promising carrier for the mass transport of hydrogen and facilitates the production of COx-free hydrogen by decomposing into nitrogen and hydrogen. Ru nanoparticles are uniformly dispersed on the Mg–Al oxide layer of the FeCralloy monoliths and foams via precipitation. The catalytic activities depend on the surface area and loading of the catalysts and the metal dispersion in the oxide layer. At temperatures <650 °C, and a gas hourly space velocity (GHSV) of 3,000 h−1, monolithic catalysts with a large surface area and evenly distributed active metals perform excellently. Foam catalysts with excellent heat transfer performance better at temperatures >650 °C and GHSV >6,000 h−1. Foam catalyst stability is verified for 100 h in a 20 Nm3/h high-purity hydrogen production system.

Experimental study on the characteristics of loop heat pipe with modified carbon fiber felt wick

In order to achieve accurate and effective thermal management of high-performance electronic components, the performance of a small flat loop heat pipe was investigated. A flexible composite capillary wick material has been applied in a flat loop heat pipe. Surface modification of carbon fiber felt was carried out using arc spraying technology to make it a more suitable material for producing capillary wicks. The physical properties of the modified carbon fiber felts were determined by measuring their wettability, porosity, capillary force, and thermal conductivity. A small flat loop heat pipe assembled with carbon fiber felt wick was designed and fabricated, and experimental testing was conducted. The experimental data indicated that the performance of methanol was better than that of acetone and water. The loop heat pipe with a 60% filling ratio maintained the heat source temperature at 84.47 °C under a load of 120 W (30 W/cm2). Conditions where the heat source starts before the cooling system are more favorable for the quick and stable startup of the loop heat pipe. The experimental results demonstrated that the loop heat pipe with a modified carbon fiber felt wick exhibited excellent operational and heat transfer performance.