Mechanism Of Heat Transfer Enhancement Research Articles

Experimental study on enhanced heat transfer mechanism of U-shaped buried pipe by bio-microbial method

Thermal conductivity of soil is the key factor affecting utilization efficiency of ground source heat pumps (GSHPs). The microbially induced carbonate precipitation (MICP) technology has been proved to be an effective method to improve the thermal conductivity of soil. However, studies on using MICP treated soil as backfill to improve heat transfer performance of GSHP system is still rare. In this study, a small laboratory test device was developed to analyze the effects of different MICP treatment cycles on the heat transfer performance of GSHPs, taking into account four influencing factors: soil temperature, heat transfer and soil ultra-mild soil temperature recovery rate. The results show that MICP treated soil as backfill can improve heat transfer performance of GSHP to a certain extent, and the heat transfer amount in soil are 14.2 %, 34.9 % and 40.1 % corresponding to one to three MICP treatment cycles, which was higher than that of untreated soil. The longer the operation time, the more continuous heat dissipation or heat absorption of the system, the greater the heat transfer radius of the buried pipe temperature. For the influence of number of MICP treatment cycles, heat transfer effect of MICP-treated soil treated three times as backfill is the best. The temperature recovery rate of soil at the central test point of backfill area in summer is 73.15 %, followed by the temperature recovery rate of MICP-treated soil treated twice and treated once, which are 70.95 % and 69.6 % respectively. Considering heat transfer effect, treatment time and treatment cost, secondary MICP treated soil as backfill is the most cost-effective. Through scanning electron microscopy (SEM) image analyses, it is found that calcium carbonate acts as a “thermal bridge” between soil particles, increasing the contact surface between soil particles, resulting in improved heat transfer efficiency among soil particles, and thus improving the thermal conductivity of soil. The results provide good insight for the selection of GSHP layout, operation mode and environmental backfill in engineering practices.

Numerical study on enhanced heat transfer and friction factor characteristics of helical bead-groove tube

The comprehensive thermo-hydraulic performance of a helical tube (HT) is improved in this study by proposing a new type of helical bead-groove tube (HBGT). The heat transfer performance and friction factor of HBGT, helical groove tube, and HT under the same conditions were compared by the numerical simulation method. The effects of different bead-groove positions, bead-groove density ratios, and depth ratios on the HBGT heat transfer and friction factor properties are analyzed. The research introduced the field synergy theory to investigate the enhanced heat transfer mechanism. The results show that the HBGT can strengthen the vortex and secondary flow intensity. Meanwhile, this structure can also reduce the average field synergy angle. Its performance evaluation criterion is increased by a maximum of 8.5% and 28.2% compared to the HBGT and the HT, respectively. Compared with the bead-groove position, the bead-groove density ratio and depth ratio have more significantly influenced the thermal performance of the HBGT. The Nusselt (Nu) and friction factor (f) correlations were calculated from simulation data with error limits of ±5% and ±10%, respectively, to forecast the Nusselt (Nu) and friction factor (f).

Thermodynamic performance study on the novel efficient flow pattern global construction evaporator

Based on the fluid-efficient flow pattern global construction heat transfer enhancement mechanism, a novel evaporator, called the efficient flow pattern global construction evaporator (EFGE), is presented to improve the in-tube evaporation heat transfer at low quality. The numerical analysis and experimental study of EFGE's thermodynamic performance are performed. Results show that the temperature distribution characteristic of the fluid-efficient heat transfer flow pattern construction is better than that of the initial fluid. The evaporation heat transfer coefficient (HTC) of EFGE is 0.34–1.04 times that of a common parallel flow evaporator (PFE), and the pressure drop of EFGE is only 80%–116 % of that of a common PFE at the quality of 0.9. The theoretical nonuniformity of the evaporation HTC between low- and high-quality flow is approximately 12%–67 %, which is 55%–72 % of the pressure drop. The numerical analysis results agree with the finding that EFGE has better thermodynamic performance than PFE in terms of friction power reduction and minimum entropy generation number.

Flow and heat transfer of nanofluids in a cylindrical permeable wavy channel embedded in porous medium using Buongiorno’s model

This investigation deals with the flow of Al2O3–water nanofluid in a wavy porous channel embedded in porous rocks. Fluid exchange takes place uniformly between porous rocks and the wavy channel. In this analysis, cylindrical and parallel plate wavy porous channels are considered. Consequences of Brownian motion and thermophoresis on the flow inside a wavy porous channel are elucidated. The modeled equations are made dimensionless by using dimensionless quantities. Impacts of flow parameters on the velocity, temperature, Nusselt number and friction factor are depicted through graphs. The numerical results with respect to parallel plate wavy porous channel are validated by comparing with the published results. The effectiveness of the cylindrical wavy porous channel as a heat transfer enhancement device in comparison to the parallel plate wavy porous channel is confirmed in this study. Designing devices at microlevels and understanding the heat transfer enhancement mechanism in wavy channels using the nanoparticle addition are the major outcomes from the results of this numerical investigation. The heat and mass transfer rate enhancements in the wavy porous channels are due to the higher Brownian motion in the boundary layer region and accelerated thermophoresis through thermal and concentration boundary layer thicknesses.

Study on the efficient heat transfer mechanism of microchannel pin-fin arrays under low pumping power

The efficient heat transfer with low pressure loss has long been a critical challenge in the microchannel heat sinks (MCHS) design. Further study is required for the quantitative analysis of the longitudinal vortex heat transfer enhancement mechanism. In this research, a microchannel heat transfer experiment and corresponding simulations are conducted. Based on the common Reynolds number range in engineering applications of MCHS, the underlying causes of heat transfer enhancement and pressure loss increase in MCHS with respect to Reynolds numbers is clarified. The results show that when the Reynolds number is 400, the cylindrical wake reduces the synergistic angle between the velocity and the temperature gradient at the streamwise gap, which greatly enhances the heat transfer performance of MCHS. In addition, when the Reynolds number is 900, the early separation of the cylindrical wake vortex leads to a significant reflux near the center of the spanwise gap, which significantly increases the pressure loss. A Different Reynolds number Efficiency Evaluation Criterion (DEEC) is proposed for evaluating the performance of MCHS. It is found that the flow state of cylindrical wake with Reynolds number of 400 has the best heat transfer efficiency. The concept of introducing longitudinal vortices into the pin–fin array can serve as a key guideline in the heat transfer enhancement optimization design of MCHS.

Micro-channel topology optimization based on enhanced heat transfer mechanism

Topology optimization modifies the material distribution in the design domain to produce micro-channel structure with improved thermal performance. In this work, five heat dissipation micro-channel structures with various design domain aspect ratios are optimally designed based on the bi-objective topology optimization method. The optimal design variable fields, temperature fields, and pressure fields are subsequently obtained for each operating condition, and the flow heat transfer effect and the enhanced heat transfer mechanism are investigated under various working conditions. On this basis, the flow heat transfer impact of micro-channels under various operating situations is optimized and studied by combining the field synergy concept and entransy dissipation theory. The findings show that when the Reynolds number rises in the laminar flow region, the complexity of the topological flow channels also rises. The average temperature, Tave,decreases, Nusselt number rises, the inlet and outlet pressure drop, ?P, gradually increases, the integrated enhanced heat transfer factor PEC gradually decreases, the field synergy number, Fc, increases, the pressure drop synergy angle, ?, gradually increases, the entransy dissipation, Evh, increases, and the flow heat transfer performance of each heat dissipation channel is also enhanced due to the complex channels and high Reynolds number in the domain. The investigation of micro-channels with various topologies revealed that the micro-channels with the same boundary conditions and a design domain aspect ratio of 25/64 had the best synergy effects of velocity-pressure gradient and velocity-temperature gradient, the best heat transfer effect, and the best flow characteristics.

Heat transfer enhancement mechanism of elliptical cylinder for minichannels with delta winglet longitudinal vortex generators

In order to improve the heat transfer performance in the minichannel with delta winglet longitudinal vortex generators and obtain the heat transfer enhancement mechanism, the flow and heat transfer of four basic models (CFD-I, CFD-V, CFU-I and CFU-V configurations) and four enhanced models with elliptical cylinders are numerically simulated in the range of Reynolds number from 2500 to 10,000. The friction factor, Nusselt number and thermal performance factor are evaluated, and the secondary flow intensity and entropy generation rate are analyzed. The main conclusions are as follows: compared with the basic models, the Nusselt number increase by 8.4–14.1 %, 6.1–12.0 %, −1.9-5.0 % and 11.0–14.9 % respectively after adding the elliptical cylinders, and the thermal performance factor of these four models with elliptical cylinders are within 1.05–1.25, 1.00–1.13, 0.97–1.16 and 1.03–1.22, respectively. Compared with the smooth channel, the Nusselt number of CFD-V and CFU-I configurations with elliptical cylinders increased by up to 61 % and 63 %, respectively, and the overall thermal performance increased by up to 25 % and 22 %, respectively. These two configurations are recommended because they make full use of the fluid accelerated by the elliptical cylinder and effectively improve the strength and influence range of the longitudinal vortexes.

Experimental and numerical study on thermofluidic characteristics of microchannel heat sinks with various micro pin-fin arrays arrangement patterns

Targeting at improving the comprehensive performance of microchannel heat sink, microchannel heat sinks integrated with various arrangements of micro pin-fins arrays are proposed in this paper. The thermofluidic characteristics and heat transfer enhancement mechanism of different pin-fins arrangement patterns is investigated by experimental test and numerical simulations. It is found that the partially uniform/gradient stagger pin-fins arrangement patterns present largest pressure drop with moderate heat dissipation performance, while the patterns with overall pin-fins distribution demonstrate superior heat transfer performance than all partial pin-fins distribution modes. Thus, overall gradient stagger pin-fins arrangement with moderate pressure drop yields optimal heat transfer capacity, achieving 4.8∼6.1 times enhancement than smooth channel. Furthermore, the partially uniform/gradient stagger pin-fins arrangement patterns indicate best temperature uniformity and thermal resistance with 26.2 K and 47.6% reduction than smooth channel at 80 ml/min, 100 W/cm2, respectively. The temperature trend in the longitudinal direction shows peaks and troughs for arrangements with partial pin fins distribution, while patterns of gradient pin fins distribution exhibit wavy curves of temperature rise. Additionally, the performance evaluation plot is adopted to describe the comprehensive performance of heat sinks with different pin fins patterns. It is observed that the overall gradient stagger pin-fins arrangement shows optimal comprehensive performance among all patterns, achieving heat transfer enhancement ratio greater than 4 in contrast with smooth channel. Finally, the correlations of Nusselt number and apparent friction factor for patterns are established. This study provides feasible insights on the performance improvement of microscale liquid cooling technologies for thermal management of electronic devices.

Flow and heat transfer characteristics in adaptive latticework structure designed using shape memory alloys

In this study, numerical simulation and particle image velocimetry experiments were performed to investigate an adaptive flow and heat transfer control structure based on shape memory alloy operating in the range of Reynolds number 100 to 2000. The adaptive structure could operates with low drag coefficient in the flat state, and actively enhance heat transfer with a latticework channel structure in the warping state. Different warping heights and Reynolds numbers were investigated to analyze the flow patterns and heat transfer enhancement mechanism. The warping of the shape memory alloy leads to flow deflection and generates a z-direction velocity component around the gap, which is the main reason for local heat transfer enhancement. The average velocity in the main stream plane (XY plane) close to the heat transfer surface increases sharply with warping. This study found significant increase in normal velocity and in-plane velocity (up to 0.17 and 0.94 times reference inlet velocity uin) in the plane at a distance of 0.1 times hydraulic diameter Dh from the wall due to warping, which strengthens the disturbance near the wall and thus enhances heat transfer. The longitude vortices generated in the structure are divided into the main vortex in the center of the channel and the corner vortex in the sub channel. The corner vortex is mainly caused by the gap flow between the shape memory alloy and the wall surface. In the warping state, the average value of the main stream velocity components near the wall is relatively close to the numerical simulation results (by deviation of 0.04 uin). In numerical results, the structure can achieve a heat transfer regulation ratio of 2.5–3.3 times and a resistance regulation ratio of 5.2–14.6. The performance parameters are not monotonous with the increase of the warping height or the Reynolds number. When the warping height is 0.6 Dh and Reynolds number equals to 400, maximum performance factor (1.34) is achieved.

Venturi effect-based simulation of air-based PVT optimization

ABSTRACT Air-based photovoltaic thermal(PVT) solar collectors can convert solar energy into both electrical and thermal energy. However, the output efficiency was often low due to the limitation of the heat transfer capacity for air. Therefore, in this paper, an air-based PVT with the application of a novel rib was modeled and numerically simulated. The innovation of this paper was proposing a novel rib, which was based on the Venturi effect. First, the effects of the new rib control parameters on the performance of the PVT system were analyzed using orthogonal design tests. The result showed that the thermal efficiency of the best factors combination test was 51.16% when the solar radiation was 500 W / m 2 and the air inlet rate was 0.09 m / s . Second, analyzing the fluid flow characteristics and the enhanced heat transfer mechanism, this study found that the increased air velocity under the novel rib and the low-velocity vortex formed between the rib both negatively affected heat transfer. Consequently, this paper proposed a novel fin design coupled with curved fins to address the issues with the novel rib design, which achieved 55.12% thermal efficiency with the combination structure. Finally, we applied the combined structure to the PVT system, studied its thermal efficiency under real-world conditions, and compared it with the empty channel collector. The results showed significant improvement, with a 16.38% increase in thermal efficiency and the model exhibited excellent, stable performance.

Experimental study on combined heat transfer enhancement due to macro-structured surface and electric field during electrospray cooling

Electrospray (ES) cooling is promising to achieve the high-heat-flux thermal dissipation with a low fluid consumption when using structured surfaces as heat sinks of micro-size and high-power electronics. Nevertheless, available research is still limited in the fundamental of combined heat transfer enhancement owing to the macro-structured surface and electric field. In this study, four macro-structured surfaces machined with cubic pin fins, conical pin fins, wavy fins and straight fins are compared to one flat surface under electric field to shed lights on the combined heat transfer enhancement mechanism during ethanol ES cooling. The experimental results demonstrate that both electric field and surface modification can elevate the critical heat flux (CHF) and heat transfer coefficient. A CHF of 7.93 W/cm2 is achieved by the cubic-pin-fin surface with an applied voltage of 4.5 kV at Ts = 145 °C, corresponding to a 63 % enhancement over the flat surface. The CHFs at first increase and then decline with the increased area ratio (f), and the superior heat transfer performance is achieved when f = 0.79. In the low temperature region (30 °C < Ts < 51 °C), the enhanced convection and bubble formations caused by electric field are deemed as the dominated heat transfer mechanism. The increase in nucleation sites triggered by macro-structured surfaces governs the heat transfer in the mid-temperature region (51 °C < Ts < 119 °C). Whereas, the heat transfer enhancement due to macro-structured surfaces declines in the high temperature region (Ts > 119 °C), possibly as a consequence of the large thermal resistance induced by the Leidenfrost phenomenon.

Enhanced radiation heat transfer performance of Alumina-Spinel composite sphere with hollow structure for rapidly ultra-high temperature thermal storage/release process

Heat storage technologies for high temperatures have recently been gaining increasing attention. For heat storage applications at high temperatures, such as industrial regenerative burner systems, the impact of radiant heat transfer on the efficiency of rapid heat storage and release cannot be ignored. Hence, the development of heat storage materials with high infrared radiation absorption is of great significance for energy saving and CO2 emission reduction. Consequently, this study innovatively proposes an advanced composite heat storage material, composited by alumina and a Fe-Co-Mn-Al spinel, with the aim of improving absorptivity. A medium-entropy approach is employed to improve IR absorptivity of alumina. Through the strategic adding of various transition metal oxides, the radiative absorptivity of the alumina material in the 600–1200 °C range increased from an initial 0.2 to an impressive 0.8, provided that doping additives remain below 10 wt%. The high-temperature heat storage material balances cost, heat recovery efficiency and thermal stability. In addition, the heat storage material is prepared as a hollow sphere to further enhance the heat storage density of rapid heat storage/release and reduce cost. Multi-scale numerical simulations are carried out to reveal the heat transfer enhancement mechanisms of modified materials and hollowing. radiative modification can significantly increase the heat storage and release capacity, especially at ultra-high temperatures above 1000 °C. Experimental evaluations using an actual regenerative burner further confirmed the heat recovery performance of this novel heat storage sphere. Comparing with conventional regenerative burner system, heating power remarkably increased by 24.6 %, and the heat storage density of packed bed improved by 16.7 %. This study promises to significantly improve the efficiency of rapid heat recovery at high temperature.

Analysis of the mechanism of enhanced heat transfer by nanofluids.

Industrial production and humans cannot exist without energy, but the low efficiency of the heat transfer in the excessive use of energy is the most significant aspect of energy saving and emission reduction. Molecular dynamics simulation methods are devoted to simulate the heat transfer efficiency of a nanofluid system with different particle sizes, and the heat transfer enhancement mechanism of the nanofluid is simulated and studied from a microscopic perspective. The analysis showed that as nanoparticle size increases, the thermal conductivity of the Al-Ar nanofluid tends to decrease, but all of them are still higher than the thermal conductivity of the liquid argon system. According to the findings of the density and radial distribution function analyses, it can be seen that the microstructure of the system changes after putting solid nanoparticles to the original fluid. This alteration in the system's microstructure is the primary component responsible for the increased heat transfer efficiency of nanofluids. In this paper, based on the theory of molecular dynamics, the simulation calculations were mainly performed using LAMMPS software, which is a commonly used open source computational program in the field of MD simulation research. VMD is used for visualization and analysis. The Lennard-Jones potential function was used in the simulation to accurately describe the forces acting between the atoms.

Study on heat transfer and flow resistance characteristics of cracking furnace tube by axial width of opening combination rotor blade

Based on the passive enhanced heat transfer mechanism, this paper proposes the new opening combination rotor blade, which aims to improve heat and mass transfer performance by changing internal structure of cracking furnace tube, thus achieving efficient production of ethylene. Through mathematical modeling and simulation of heat transfer properties of opening combination rotor blade, heat transfer performance and fluid flow characteristics of ordinary rotor blade tubes and opening combination rotor blade with axial widths of W (W = 0.25 R, 0.5 R, 0.75 R) are analyzed using field synergy principle and comprehensive heat transfer evaluation coefficient (PEC).The results demonstrate that the Nusselt number of opening combination rotor blade is 19%-23% lower than that of ordinary rotor blade. The resistance coefficient of opening combination rotor blade with axial width of 0.25 R is significantly lower by 33%-43%. Opening combination rotor blade with axial width of 0.25 R has a significantly lower resistance coefficient of 72%-78%. Its PEC value is between 1.23–1.28 with significantly improved overall heat transfer performance. In summary, opening combination rotor blade with axial width of 0.25 R has the most significant heat transfer effect and has a high reference significance for engineering design.

Numerical investigation of air–steam condensation in a vertically enhanced tube with dimples and protrusions

The thermo-hydraulic performance of air–steam condensation in a vertically enhanced tube with dimples and protrusions is investigated numerically. A forming experiment is conducted to test the validity of the physical model establishment. The heat transfer enhancement mechanism is investigated. In addition, the effects of inlet air mole fraction, the depth and pitch of the dimples on thermo-hydraulic performance are presented and discussed. The results showed that the error between the actual manufacture and mechanical simulation geometric model is less than 15 %. The structure of interlaced dimples and protrusions can disrupt the air concentration layer, promote fluid mixing, and eventually enhance the heat transfer between steam and condensing walls. The lower inlet air mole fraction, greater dimple depth, and longer dimple pitch of the enhanced tube, the better thermo-hydraulic performance is obtained. Among all the cases, the best design of geometric parameters occurs when the inlet air mole fraction, the dimple depth, and the pitch are 10 %, 4 mm, and 25 mm respectively. In addition, the comprehensive heat transfer performance is compared among different enhanced tubes and the results show that the enhanced tube with dimples and protrusions has better comprehensive heat transfer performance.

Numerical simulation study of flow and heat transfer characteristics of the spiral ribbed tube with elliptical dimples

In this study, a new type of spiral rib-reinforced heat transfer tube with elliptical dimples (referred to as SRTED) is proposed. Numerical simulations were performed to investigate the effect of different geometric parameters on the flow and heat transfer characteristics. The field synergy theory was adopted to reveal the enhanced heat transfer mechanism. The results demonstrated that the flow velocity reaches the maximum at the smallest cross-sectional area in the tube; besides, it tends to decrease with the increase of the cross-sectional area in the tube. The distribution trend of the local heat transfer coefficient (h) of SRTED has a periodic pattern; the average value is 1.41 times that of the plain tube and 1.13 times that of the dimpled tube. In the calculated Re range, the Nu/Nu0 of SRTED varies from 2.84 to 4.46, and f/f 0 varies from 8.98 to 23.51. The overall thermal performance evaluation criterion (PEC) value varies from 1.18 to 1.78, with higher PEC at low flow rates.

Coupling dynamic thermal analysis and surface modification to enhance heat dissipation of R410A spray cooling for high-power electronics

With high critical heat flux (CHF) and heat transfer coefficient (HTC), spray cooling is considered as one of the most promising thermal management technologies for high-power electronic devices. To increase its cooling performance, a closed-loop experimental rig was constructed to study the effects of spray and system parameters on heat transfer enhancement by R410A. The best cooling performance can be achieved under optimal subcooling degree of 17 °C and nozzle diameter of 0.56 mm. When the compressor frequency reaches the upper limit of 90 Hz, maximum CHF and HTC on flat surface are 301.6 W/cm2 and 91.7 kW/(m2·K). To further improve CHF, mechanism of heat transfer enhancement by square pin finned surface was revealed in terms of droplet splashing. With fin width of 0.5 mm and height of 3 mm, CHF as high as 522.1 W/cm2 and peak HTC of 407.0 kW/(m2·K) are reached, while maintaining the cooling surface temperature lower than 55.6 °C. Compared to flat surface, CHF and HTC are enhanced by around 73.4% and 3.5 times, respectively. Based on the experimental data, CHF correlation applicable to pin finned surface was obtained with precision of ±12.4% by introducing fin height and width.

Numerical and experimental investigation on condensing heat transfer and flow characteristics outside horizontal dentate-fin tubes

The condensing flow and heat-transfer characteristics around dentate-fin tubes were investigated using numerical and experimental methods. Using the examined computational model, the film flow characteristics and condensing heat-transfer coefficient of the dentate-fin tubes in the circumferential and axial directions were analyzed. Comprehensive information regarding the condensation process in high-performance tubes is provided for the first time. The results showed that the circumferential and axial film thicknesses of the dentate-fin tubes increased with increasing fin density. The liquid film distribution of dentate-fin tubes with a low fin density was relatively uniform, and condensate drainage was easy. The special heat-transfer structure of dentate-fin tubes was examined, and it was found that the complex heat-transfer structure led to variations in the surface tension, which changes the liquid-film distribution. The local condensing heat-transfer coefficient of the dentate-fin tubes was very sensitive to the liquid-film distribution. The optimal fin density corresponding to the maximum overall heat-transfer coefficient was obtained, which showed that the mechanism of heat-transfer enhancement for dentate-fin tubes was a joint effect of the heat-transfer area and liquid-film thickness.

A Review: Study on the Enhancement Mechanism of Heat and Moisture Transfer in Deformable Porous Media

The heat and moisture transfer process in deformable porous media commonly exists in material drying, solid waste treatment, bioengineering, and so on. The transfer process is accompanied by deformation of the solid skeleton and pore interface structure, which limits the transfer rate and affects quality. Microwave and ultrasound are the main representatives of reinforcement technology. However, as the moisture decreases, the energy utilization efficiency of microwaves decreases significantly. Based on the experimental and theoretical methods, the enhancement mechanism of ultrasound on the process is studied, which provides guidance for the wide application of ultrasonic enhancement. With the increase in ultrasound power, the pore area and the moisture effective diffusion coefficient gradually increase. A macroscope mathematical model for ultrasonic-coupled thermal-hydro-mechanical modeling is developed, and the results show that ultrasound increases the temperature gradient within material, resulting in higher moisture transmission rates with an ordered direction, and the alternating expansion and compression process results in smaller macroscopic deformations. Subsequently, the drying kinetic characteristics of typical deformable porous media such as municipal sludge, porous fibers, and activated alumina particles are investigated. The process parameters of the ultrasonic assisted drying system are optimized using the response surface method and artificial neural network model.

The heat transfer enhancement of the converging-diverging tube in the latent heat thermal energy storage unit: Melting performance and evaluation

Latent heat thermal energy storage (LHTES) has emerged as a promising approach to settle the intermittent and fluctuant of renewable energy but heat transfer enhancement is necessary due to the low thermal conductivity of the phase change material (PCM). This study numerically investigated the heat transfer enhancement effect of the typically converging-diverging tubes (CDTs) inside a shell-and-tube LHTES unit. The evolution of melting behavior was analyzed to describe the heat transfer enhancement mechanism of the CDT. Based on the enhancement effect and pump power consumption associated with the CDT, a modified performance evaluation criterion (PEC) was established to evaluate the feasibility of current designs. The arrangement of CDTs was found to significantly improve the heat transfer performance of LHTES. The triangle CDT exhibited the maximum melting time reduction of 20.77%. The heat transfer enhancement effect of CDT was attributed to the enhanced natural convection of PCM and forced convection of heat transfer fluid. The analysis of the evaluation ensures the feasibility of the new criterion and its specific application field. Moreover, it was worth to note that the triangle CDT achieved the best cost performance of 0.363 ω, where ω represented the return factor.