Browsing by Author "Lu, Ming-Chang"

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A modified hydrodynamic model for pool boiling CHF considering the effects of heater size and nucleation site density
(2015-05-01)
Lu, Ming-Chang
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Huang, Chih-Hung
;
Huang, Chung-Te
;
Chen, Yu-Chi
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機械工程學系
Boiling is commonly used in daily life and is an efficient heat removal method. During pool boiling, the critical heat flux (CHF) establishes the upper limit of efficient heat removal. Although, numerous studies have explored CHF, its exact mechanisms remain ambiguous. The hydrodynamic instability model is the most prominent CHF model, but it fails to explain the evident dependence of CHF on surface properties. The authors proposed modifying the hydrodynamic model to account for how nucleation site density and finite heater size affect the CHF. The experimental CHF values obtained from evaluating various types of surfaces qualitatively agreed with the predictions of the modified hydrodynamic model. This suggests that the CHFs on these surfaces were due to the hydrodynamic limit. (C) 2015 Elsevier Masson SAS. All rights reserved.
A solar-thermal energy harvesting scheme: enhanced heat capacity of molten HITEC salt mixed with Sn/SiOx core-shell nanoparticles
(2014)
Lai, Chih-Chung
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Chang, Wen-Chih
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Hu, Wen-Liang
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Wang, Zhiming M.
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Lu, Ming-Chang
We demonstrated enhanced solar-thermal storage by releasing the latent heat of Sn/SiOx core-shell nanoparticles (NPs) embedded in a eutectic salt. The microstructures and chemical compositions of Sn/SiOx core-shell NPs were characterized. In situ heating XRD provides dynamic crystalline information about the Sn/SiOx core-shell NPs during cyclic heating processes. The latent heat of similar to 29 J g(-1) for Sn/SiOx core-shell NPs was measured, and 30% enhanced heat capacity was achieved from 1.57 to 2.03 J g (1) K (1) for the HITEC solar salt without and with, respectively, a mixture of 5% Sn/SiOx core-shell NPs. In addition, an endurance cycle test was performed to prove a stable operation in practical applications. The approach provides a method to enhance energy storage in solar-thermal power plants.
Control of Ice Formation
(2017-03-01)
Lo, Ching-Wen
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Sahoo, Venkataraman
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Lu, Ming-Chang
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機械工程學系
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Department of Mechanical Engineering
Ice formation is a catastrophic problem affecting our daily life in a number of ways. At present, deicing methods are costly, inefficient, and environmentally unfriendly. Recently, the use of superhydrophobic surfaces has been suggested as a potential passive anti-icing method. However, no surface is able to repel frost formation at a very cold temperature. In this work, we demonstrated the abilities of spatial control of ice formation and confinement of the ice-stacking direction. The control and confinement were achieved by manipulating the local free energy barrier for frosting. The V-shaped microgroove patterned surface, which possessed these abilities, exhibited the best anti-icing and deicing performances among the studied surfaces. The insight of this study can be applied to alleviate the impact of icing on our daily life and in many industrial systems.
Critical heat flux of pool boiling on Si nanowire array-coated surfaces
(2011-12-01)
Lu, Ming-Chang
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Chen, Renkun
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Srinivasan, Vinod
;
Carey, Van P.
;
Majumdar, Arun
Pool boiling of saturated water on plain Si surfaces and surfaces covered with a dense array of Si nanowires (SiNWs) has been studied. Measured CHF and heat transfer coefficient (HTC) values of about 223 +/- 5.61 W/cm(2) and 9 +/- 1.60 W/cm(2) K. respectively, on the nanowire array-coated surface are among the highest reported in boiling heat transfer. Meanwhile, the CHFs on both nanowire-coated and Plain Si surfaces show a similar heater size dependence - the CHF increases as heater size decreases. The measured CHFs on both types of surfaces are approximately following the prediction of the hydrodynamic theory assuming the Helmholtz wavelength equal to the corresponded heater length. It suggests that the CHFs on both types of surfaces might be limited by pool hydrodynamics. (C) 2011 Elsevier Ltd. All rights reserved.
Elongated Bouncing and Reduced Contact Time of a Drop in the Janus State
(2018-09-18)
Sahoo, Venkataraman
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Chou, Chu-Yao
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Lo, Ching-Wen
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Lu, Ming-Chang
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機械工程學系
Fast drop bouncing is desired in numerous applications. However, it has never been realized on a superheated surface with concurrent contact boiling and the Leidenfrost effect (the so-called Janus thermal state). This is presumably because of the increased drop adhesion as a result of bubbling on a Janus surface. Nevertheless, on a hydrophilic SiNx surface with v-shaped Si microgrooves in this thermal state, an elongated bouncing for a water drop was observed and a small drop contact time of 10.36 ms was obtained. We propose that the elongated bouncing was originated from an asymmetric momentum force created by the vapor bubbles at the rim of the drop. Analytical expressions for the contact time and the asymmetric momentum force were established and the predictions qualitatively agreed with the experimental results. The obtained contact time was the lowest value that has ever been reported in the Janus thermal state. The proposed approach has promising applications in state-of-the-art technologies requiring high liquid mobility.
Enhanced Heat Transfer in Biporous Wicks in the Thin Liquid Film Evaporation and Boiling Regimes
(2012-10-01)
Coso, Dusan
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Srinivasan, Vinod
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Lu, Ming-Chang
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Chang, Je-Young
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Majumdar, Arun
Biporous media consisting of microscale pin fins separated by microchannels are examined as candidate structures for the evaporator wick of a vapor chamber heat pipe. The structures are fabricated out of silicon using standard lithography and etching techniques. Pores which separate microscale pin fins are used to generate high capillary suction, while larger microchannels are used to reduce overall flow resistance. The heat transfer coefficient is found to depend on the area coverage of a liquid film with thickness on the order of a few microns near the meniscus of the triple phase contact line. We manipulate the area coverage and film thickness by varying the surface area-to-volume ratio through the use of microstructuring. Experiments are conducted for a heater area of 1 cm(2) with the wick in a vertical orientation. Results are presented for structures with approximately same porosities, fixed microchannel widths w approximate to 30 mu m and w approximate to 60 mu m, and pin fin diameters ranging from d = 3-29 mu m. The competing effects of increase in surface area due to microstructuring and the suppression of evaporation due to reduction in pore scale are explored. In some samples, a transition from evaporative heat transfer to nucleate boiling is observed. While it is difficult to identify when the transition occurs, one can identify regimes where evaporation dominates over nucleate boiling and vice versa. Heat transfer coefficients of 20.7 (+/- 2.4) W/cm(2)-K are attained at heat fluxes of 119.6 (+/- 4.2) W/cm(2) until the wick dries out in the evaporation dominated regime. In the nucleate boiling dominated regime, heat fluxes of 277.0 (+/- 9.7) W/cm(2) can be dissipated by wicks with heaters of area 1 cm(2), while heat fluxes up to 733.1 (+/- 103.4) W/cm(2) can be dissipated by wicks with smaller heaters intended to simulate local hot-spots. [DOI: 10.1115/1.4006106]
Enhanced immersion cooling using two-tier micro- and nano-structures
(2018-02-25)
Hsu, Ya-Tzu
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Li, Jia-Xiong
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Lu, Ming-Chang
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機械工程學系
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Department of Mechanical Engineering
Continual increases in the functionality and miniaturization of electronic devices have resulted in a rapid increase in the power density of such devices. Thus, an efficient cooling technology is required to maximize heat dissipation and prevent electronic failure. Immersion cooling is a promising technique for the thermal management of high-power-density electronics. However, common working fluids in immersion cooling have high global warming potential, and the heat transfer performance of immersion cooling requires improvement to achieve efficient cooling of state-of-the-art high-power-density electronics. In this study, Novec 649, which has low global warming potential and a low boiling point, was applied as a working fluid for immersion cooling. A Si nanowire (SiNW) array, Si micropillar (SiMP) array, and Si nanowires on a Si micropillar (SiNW/MP) two-tier structure were employed to enhance boiling performance. The SiMP surface exhibited the highest critical heat flux (CHF) of 23.5 +/- 1.3 W/cm(2), whereas the SiNW surface exhibited the lowest CHF but a relatively high heat transfer coefficient (HTC). The SiNW/MP surface exhibited the highest HTC of 23611.7 +/- 1586.2 W/m(2) K and a relatively large CHF of 17.4 +/- 1.2 W/cm(2). Compared with a plain SiO2 surface, the CHF and HTC of the SiNW/MP two-tier structure could be enhanced by 30% and 455%, respectively. These results suggest that the SiNW/MP surface is effective for enhancing immersion cooling. (C) 2017 Elsevier Ltd. All rights reserved.
Enhancing Condensation Heat Transfer on Three-Dimensional Hybrid Surfaces
(2019-11-20)
Lo, Ching-Wen
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Chu, Yu-Cheng
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Yen, Ming-Han
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Lu, Ming-Chang
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機械工程學系
In recent years, micro/nanostructured surfaces have been applied to enhance condensation heat transfer. However, condensation heat transfer is greatly deteriorated by the flooding phenomenon that occurs at high subcooling temperatures. Here, we propose a three-dimensional (3D) hybrid surface to enhance the condensation at high subcooling temperatures. The 3D hybrid surface consisted of superhydrophobic (SHB) Si nanowire (SiNW) arrays and hydrophilic microchannels. The microchannels could confine the liquid-film thickness, and the liquid bridges formed on the 3D hybrid surfaces could be self-removed. Both of these characteristics prevent the surfaces from flooding. In addition, liquid droplets formed in the SiNW regions were dragged into the microchannels, which also improved the heat transfer. The heat transfer coefficient on the 3D hybrid surface could be enhanced over a large subcooling range. More remarkably, a record high heat flux of 655 +/- 10 kW.m(-2) was obtained on the 3D hybrid surface.
Experiments for suitability of plastic heat exchangers for dehumidification applications
(2019-07-25)
Amer, Mohammed
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Chen, Miao-Ru
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Sajjad, Uzair
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Ali, Hafiz Muhammad
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Abbas, Naseem
The present study conducted a series of experiments concerning the condensation of humid air used in a typical adsorption dehumidifier. The experiments were carried out with the standard ambient condition (27 degrees C dry bulb temperature and 21.2 degrees C wet bulb temperature) for the cold side. Yet the regeneration side (hot side) inlet temperature is 55 degrees C with RH% being 100%. Three novel plastic heat exchangers (plate plastic heat exchanger-PHX, bare tube plastic heat exchanger with asymmetry tube layout-BTHX, and round tube plastic heat exchanger with uniform tube layout-RTHX) were tested and compared experimentally. Test results, in terms of heat flux or heat transfer coefficient, show that the BTHX is superior to RTHX and PHX for offering additional condensate splashing mode. The splashing feature is especially beneficial for larger cold side flow rate since the plateau of heat transfer performance is moved toward larger cold side flow rate regime. The asymmetry tube geometry design (BTHX) shows even better heat transfer performance than the uniform tube bundle design (RTHX) for providing more space at the downstream of the tube bundle.
Heat Transfer of Semicrystalline Nylon Nanofibers
(2020-03-24)
Chien, Hsin-Che
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Peng, Wei-Tsu
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Chiu, Te-Hsuan
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Wu, Pei-Hsiu
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Liu, Yueh-Ju
Polymers are generally regarded as thermal insulators. The efficient heat transfer observed in the low-dimensional polymers in the literature mainly result from the larger crystallinity or improved polymer chain orientation in the low-dimensional polymers. However, the role of the amorphous domain on heat transfer in polymers remains unexplored. In this work, we report that the semicrystalline nylon polymer nanofibers can exhibit a very large thermal conductivity of 59.1 +/- 3.1 W m(-1) K-1 and the heat transfer in the semicrystalline polymer nanofibers was time-dependent. The thermal conductivity of the nanofibers could be modulated to span 3 orders of magnitude from being nearly insulated (similar to 0.27 +/- 0.02 W m(-1) K-1) to being highly thermal conductive after annealing (similar to 59.1 +/- 3.1 W m(-1) K-1). The time-dependent thermal conductivity was observed at a temperature lower than the gamma transition temperature of the polymer and was a result of the physical aging of the semicrystalline polymer. A phenomenological model was adopted to explain the time-dependent heat transfer of the semicrystalline nanofibers. The physical aging reduced the configuration disorder in the polymer and caused the heat transfer of the semicrystalline polymer to increase during the annealing process.
Investigation of the two-phase convective boiling of HFO-1234yf in a 3.9 mm diameter tube
(2013-10-01)
Lu, Ming-Chang
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Tong, Jing-Rei
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Wang, Chi-Chuan
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機械工程學系
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Department of Mechanical Engineering
In this study, the influences of heat flux and mass flux on the two-phase convective boiling heat transfer performance are reported for refrigerants HFO-1234yf and HFC-134a in a 3.9 mm smooth diameter tube. Tests are performed with a saturation temperature of 10 degrees C. It is found that at lower vapor quality region the nucleate boiling is the dominant heat transfer mechanism while the convective evaporation mechanism takes control at the higher vapor quality region. Both HFC-134a and HFO-1234yfshows similar trend and the difference in heat transfer coefficient between HFO-1234 and HFC-134a is quite small. The comparable heat transfer performance between HFC-134a and HFO-1234yf is attributed to similar physical properties and nucleate boiling contribution. The present test results are in line with some existing reports but are inconsistent with one other study having a tube diameter of 1.1 mm. It is found that the departure of heat transfer coefficients between the available publications is mainly attributed to the different flow phenomena caused by the difference of the channel size and channel geometry. A noticeable deterioration of the heat transfer coefficient for HFO-1234yf is encountered in the microchannel. The pressure drops for HFC-134a is about 5-15% higher than that of HFO-1234yf. (C) 2013 Elsevier Ltd. All rights reserved.
Leidenfrost suppression and contact time reduction of a drop impacting on silicon nanowire array-coated surfaces
(2020-02-01)
Sahoo, Venkataraman
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Lo, Ching-Wen
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Lu, Ming-Chang
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機械工程學系
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Department of Mechanical Engineering
Drop impacting on a superheated surface is of practical concern in several thermal systems. When the surface temperature is higher than the Leidenfrost point (LFP), a stable vapor cushion forms on the solid surface and the drop hovers over the thin vapor layer. This results in a drastic reduction in heat and mass transfer due to the thermally insulating vapor layer. The contact time of an impacting drop is the amount of time during which the drop comes in contact with the solid surface. A short contact time enhances heat transfer. Thus, a high LFP and a short drop contact time are of interest to researchers. The present study revealed substantial Leidenfrost suppression and contact time reduction on a superheated superhy-drophilic silicon nanowire (SiNW) array-coated surface. For an impacting drop of 14 mu L with a Weber number (We) of 2.0, a LFP of 655 +/- 14 degrees C was obtained on the SiNW array-coated surface with a nanowire height of 90 mu m. This LFP was the highest reported value in the literature. A theoretical modeling revealed that the elevated LFP was caused by a superior capillary force and a strong vapor dispersion into the nanowire array. In addition, contact time was substantially reduced on the superheated SiNW surface in the jet-bouncing regime. The contact time of 1.3 +/- 0.1 ms was 91% lower than the capillary-inertia limit. It was also the lowest reported value in the literature. The contact time reduction on the super-heated SiNW surface resulted from the application of an upward thrust on the impacting drop generated by the vigorous bubbling on the SiNW surface. (C) 2019 Elsevier Ltd. All rights reserved.
Scale Effect on Dropwise Condensation on Superhydrophobic Surfaces
(2014-08-27)
Lo, Ching-Wen
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Wang, Chi-Chuan
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Lu, Ming-Chang
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機械工程學系
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Department of Mechanical Engineering
Micro/nano (two-tier) structures are often employed to achieve superhydrophobicity. In condensation, utilizing such a surface is not necessarily advantageous because the macroscopically observed Cassie droplets are usually in fact partial Wenzel in condensation. The increase in contact angle through introducing microstructures on such two-tier roughened surfaces may result in an increase in droplet departure diameter and consequently deteriorate the performance. In the meantime, nanostructure roughened surfaces could potentially yield efficient shedding of liquid droplets, whereas microstructures roughened surfaces often lead to highly pinned Wenzel droplets. To attain efficient shedding of liquid droplets in condensation on a superhydrophobic surface, a Bond number (a dimensionless number for appraising drop-wise condensation) and a solid-liquid fraction smaller than 0.1 and 0.3, respectively, are suggested.
Silicon Nanowires for Solar Thermal Energy Harvesting: an Experimental Evaluation on the Trade-off Effects of the Spectral Optical Properties
(2016-01-04)
Sekone, Abdoul Karim
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Chen, Yu-Bin
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Lu, Ming-Chang
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Chen, Wen-Kai
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Liu, Chia-An
Silicon nanowire possesses great potential as the material for renewable energy harvesting and conversion. The significantly reduced spectral reflectivity of silicon nanowire to visible light makes it even more attractive in solar energy applications. However, the benefit of its use for solar thermal energy harvesting remains to be investigated and has so far not been clearly reported. The purpose of this study is to provide practical information and insight into the performance of silicon nanowires in solar thermal energy conversion systems. Spectral hemispherical reflectivity and transmissivity of the black silicon nanowire array on silicon wafer substrate were measured. It was observed that the reflectivity is lower in the visible range but higher in the infrared range compared to the plain silicon wafer. A drying experiment and a theoretical calculation were carried out to directly evaluate the effects of the trade-off between scattering properties at different wavelengths. It is clearly seen that silicon nanowires can improve the solar thermal energy harnessing. The results showed that a 17.8 % increase in the harvest and utilization of solar thermal energy could be achieved using a silicon nanowire array on silicon substrate as compared to that obtained with a plain silicon wafer.
Single bubble dynamics on superheated superhydrophobic surfaces
(2016-08)
Li, Yinxiao
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Zhang, Ke
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Lu, Ming-Chang
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Duan, Chuanhua
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機械工程學系
This work explores single bubble dynamics on superheated superhydrophobic surfaces and the corresponding heat transfer mechanism of water pool boiling. The superhydrophobic surfaces are prepared by coating a thin layer of polytetrafluoroethylene on top of silicon substrates with electroless etched silicon nanowires. It is observed that a vapor film covers the whole superhydrophobic surface when it is immersed in water. Once the surface is superheated, single bubble forms and departs from the vapor film. We find that the bubble growth rate shows little dependence on surface superheat and applied heat flux at large superheats due to the presence of the vapor layer, which seriously limits the heat transfer from the superheated superhydrophobic surface. The bubble departure diameter is mainly determined by the static force equilibrium, but local disturbance and surface superheat also play important roles. There is a plateau of bubble departure frequency at large superheats, which is a result of the constant departure velocity limit. Accompanying the continuous bubble formation and departure, a smooth boiling curve is observed. The corresponding heat transfer coefficient (HTC) first increases and then slowly decreases as the superheat increases, showing a peak at a superheat of similar to 50 K. Such HTC change is explained by the heat flux partitioning model, suggesting latent heat transport due to water vaporization and bulk liquid water convection after bubble departure contribute together to the heat removal on superhydrophobic surfaces. Insights gained from pool boiling on superhydrophobic surfaces might provide design guidelines for new surfaces excellent in heat removal or hydrodynamic drag reduction. (C) 2016 Elsevier Ltd. All rights reserved.
Spatial Control of Heterogeneous Nucleation on the Superhydrophobic Nanowire Array
(2014-03-01)
Lo, Ching-Wen
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Wang, Chi-Chuan
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Lu, Ming-Chang
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機械工程學系
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Department of Mechanical Engineering
Condensation is a common phenomenon and is widely exploited in power generation and refrigeration devices. Although drop-wise condensation offers high heat and mass transfer rates, it is extremely difficult to maintain and control. In this study, the ability to spatially control heterogeneous nucleation on a superhydrophobic surface by manipulating the free energy barrier to nucleation through parameterizing regional roughness scale on the Si nanowire array-coated surface is reported. Water vapor preferentially condenses on the designed microgrooves on the Si nanowire surface and continuous shedding of the drop-wise condensate is observed on the surface. The nucleation site density can also be manipulated by tailoring the density of the microgroove on the surface. Moreover, the cycle time on the Si nanowire array with microgrooves is approximately ten times smaller than that on a plain Si surface. This suggests that potentially high heat and mass transfer rates can be achieved on the surface. The insight from this study has implications in enhancing energy efficiency in a wide range of thermal energy conversion systems.
Specific heat capacity of molten salt-based alumina nanofluid
(2013-06-21)
Lu, Ming-Chang
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Huang, Chien-Hsun
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機械工程學系
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Department of Mechanical Engineering
There is no consensus on the effect of nanoparticle (NP) addition on the specific heat capacity (SHC) of fluids. In addition, the predictions from the existing model have a large discrepancy from the measured SHCs in nanofluids. We show that the SHC of the molten salt-based alumina nanofluid decreases with reducing particle size and increasing particle concentration. The NP size-dependent SHC is resulted from an augmentation of the nanolayer effect as particle size reduces. A model considering the nanolayer effect which supports the experimental results was proposed.
Superhydrophobic Si nanowires for enhanced condensation heat transfer
(2017-08-01)
Lu, Ming-Chang
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Lin, Chien-Chang
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Lo, Ching-Wen
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Huang, Cheng-Wei
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Wang, Chi-Chuan
Condensation is an essential process in various industrial systems. Enhancing condensation by employing superhydrophobic (SHB) surfaces had drawn significant attention in recent years because of the emerging technology for surface engineering. However, the efficacy of SHB surfaces in condensation is controversy in the literature. The observed deteriorated heat transfer on SHB in condensation is presumably a result of highly pinned Wenzel droplets or flooding formed on the SHB surfaces. Si nanowire (SiNW) array-coated surface which can simultaneously provide a large number of nucleation sites and prevent condensate from penetrating into the nano-structure is a promising candidate for enhancing condensation. In this work, heat transfer on the SHB SiNW surface was investigated. At low subcooling, jumping of liquid droplets accompanied with a high droplet departure frequency resulted in a large heat transfer coefficient (HTC) of 88 16 kW/m(2) K on the SHB surface. This value is one of the highest reported condensation HTCs in the literature. It was 155% and 87% higher than those on the plain hydrophilic and hydrophobic surfaces, respectively. Heat transfer decreased with the rise of subcooling due to an increased condensate surface coverage ratio. However, condensate can still be rapidly shed away from the SHB SiNW surface at high subcooling, which render the comparatively larger HTC of 18.6 2 kW/m(2) K on the SHB SiNW surface as opposed to plain hydrophobic and hydrophilic surfaces. It was evidenced that SHB surface could have a superior heat and mass transfer performance than hydrophobic surface provided that the liquid droplets on the SHB could be shed away efficiently. (C) 2017 Elsevier Ltd. All rights reserved.
The suppression effect of easy-to-activate nucleation sites on the critical heat flux in pool boiling
(2018-07-01)
Liu, Yi
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Lu, Ming-Chang
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Xu, Dongyan
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機械工程學系
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Department of Mechanical Engineering
We report experimental studies of the role of easy-to-activate nucleation sites in pool boiling on hybrid hydrophobic-hydrophilic surfaces. Microstructured surfaces with controlled wettability and nucleation sites are designed and fabricated to investigate their individual and collective effects on the boiling heat transfer performance. Our results reveal that excellent critical heat flux (CHF) up to 231.5 W/cm(2) is attainable only when the surface has good wettability but is free of easy-to-activate nucleation sites. However, with the presence of easy-to-activate nucleation sites on the boiling surface, only limited CHFs can be achieved irrespective of the surface wettability, suggesting a suppression effect of nucleation sites on the CHF. Based on the previous experimental observation of the dynamic network-like wetting pattern at high heat fluxes, a wetting-deterioration mechanism is proposed to explain the suppression effect of easy-to-activate nucleation sites on the CHF. Easy-to activate nucleation sites continuously generate bubbles that pose a large flow resistance for the liquid to wet the hot surface and thus lead to early dry-out.
Thermal hysteresis in phase-change materials: Encapsulated metal alloy core-shell microparticles
(2018-09-01)
Hsu, Ting-Heng
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Chung, Chieh-Hsuan
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Chung, Feng-Ju
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Chang, Chun-Che
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Lu, Ming-Chang
Thermal hysteresis (TH) is defined as the temperature difference between the melting points and crystallization temperatures of phase-change materials (PCMs). The magnitude of the TH is proportional to the energy loss in a system. In addition, the latent heats of the PCMs cannot be exploited if the TH is beyond the operation temperature range of a system. In this study, Zn/TiO2, Zn/Al2O3, and Zn/SiO2 core-shell microparticles were synthesized and the TH values of the microparticles were examined. The TH for the microparticles was mainly affected by the ramping rate in differential scanning calorimetry, the shell thermal resistance and the required temperature for heterogeneous nucleation. Given that Al2O3 possesses a superior thermal conductivity than that of TiO2 and SiO2, the Zn/Al2O3 core-shell microparticles provided the smallest TH among the three types of microparticles. The heat capacity of the salt can be enhanced by 6.7% by doping with 10 wt% Zn/Al2O3 microparticles while the viscosity increased from 1.3 to 3 cp. The study provided guidelines to modulate the TH of PCMs, and the concept learned from this study can be applied to enhancing the thermal energy storage in various thermal systems.