Rudradawong, Chalermpol

Preferred name

Alternative Name

Rudradawong, C.

Main Affiliation

School of Science

chalermpol.ru@kmitl.ac.th

Now showing 1 - 10 of 21

Some of the metrics are blocked by your
consent settings
Flexible thermoelectric generator with radiative cooling for body-heat-driven self-powered Bluetooth low energy sensing system
(2025-10-01)
Gobpant, Jakrit
;
Van Toan, Nguyen
;
Ono, Takahito
;
Tuoi, Truong Thi Kim
;
Tran, Ngoc Dang Khoa
Wearable electronics and wireless IoT sensors are increasingly expected to operate in a self-powered manner. However, their practical deployment remains limited due to the lack of compact, flexible, and sustainable energy sources. Thermoelectric generators (TEGs), which convert body heat into electricity, present a promising solution but are typically hindered by small temperature gradients and the requirement of bulky heat sinks that compromise flexibility. To address these challenges, we developed an ultra-thin flexible thermoelectric generator (FTEG) integrated with a radiative cooling (RC) layer that passively enhances heat dissipation under natural convection. The device, fabricated using high-performance thermoelectric materials on a soft silicone substrate, maintained a total thickness of just 2.26 mm. Finite element modeling and experimental validation confirmed that the RC layer effectively increased the temperature gradient across thermoelectric legs, significantly improving the output power compared to conventional graphite-based or no-cooling designs. The FTEG achieved a maximum normalized power density of 3.51 μW/cm2 under temperature conditions representative of wearable use (T<inf>skin</inf> of 32 °C and T<inf>ambient</inf> of 26 °C). The harvested energy was then stored using a power management circuit and capacitor. This stored energy was successfully used to power a Bluetooth Low Energy (BLE) sensing module, enabling stable wireless transmission driven entirely by body heat. These results highlight the practical potential of integrating passive radiative cooling into flexible thermoelectric systems, paving the way for high-performance, battery-free wearable electronics and autonomous IoT applications.
1
Some of the metrics are blocked by your
consent settings
Optimizing fabrication processes for scalable production of flexible thermoelectric modules: A case study on self-powered IoT systems
(2025-09-01)
Gobpant, Jakrit
;
Klongratog, Bhanupol
;
Rudradawong, Chalermpol
;
Sakdanuphab, Rachsak
;
Limsuwan, Pichet
This study explores the optimization of fabrication processes for flexible thermoelectric generators (FTEGs) to enhance their performance and scalability for industrial applications, with a focus on integrating them into self-powered Internet of Things (IoT) systems. The research investigates the impact of silicone layer thickness and applied fabrication pressures on the mechanical stability, energy harvesting efficiency, and power output of FTEGs. Results demonstrate that reducing the thermal conductivity of the silicone filler and optimizing the fabrication pressure significantly improves the performance of FTE modules. The optimized FTEGs, featuring a series-parallel configuration, achieve a power density of 5.2 mW/cm² under a temperature difference of 50 °C, surpassing prior benchmarks. The developed system efficiently harvests waste heat, charges a battery, and powers an IoT module for real-time monitoring of temperature, humidity, and carbon monoxide levels. These findings highlight the potential of FTEGs as a sustainable solution for energy harvesting and self-powered industrial monitoring applications.
2
Some of the metrics are blocked by your
consent settings
Effect of excess oxygen for CuFeO2.06 delafossite on thermoelectric and optical properties
(2017-12-01)
Rudradawong, Chalermpol
;
Ruttanapun, Chesta
This work presents the role of excess oxygen in CuFeO<inf>2.06</inf> compounds on thermoelectric and optical properties. The CuFeO<inf>2.06</inf> specimens were synthesized by solid state reaction method. X-ray diffraction technique has confirmed the CuFeO<inf>2</inf> structure for the specimens. In particularly, CuFeO<inf>2.06</inf> specimen revealed the structural extension of lattice parameter: a and c. Also, the specimen found increasing excess oxygen of approximately 3% as a resulted enhancement of mixed valence state of Cu+ and Cu2+ ions. XPS showed mixed valence state of the Cu+/Cu2+ ions, and Fe3+ and Fe2+ ions was also found in the CuFeO<inf>2.06</inf> specimen. Mixed valence states contributed the co-existence of hole and electron carriers for conduction. Consequently, electrical conductivity of the CuFeO<inf>2.06</inf> specimen increased up to 23 S/cm at 873 K. Also, increasing Seebeck coefficient was shown to be approximately 302 μV/K at 873 K. The CuFeO<inf>2.06</inf> specimen was found power factor to be approximately 2.1 × 10−4 W/m∙K2 at 873 K. The indirect optical gap of CuFeO<inf>2.06</inf> (2.40 eV) was lower than that of the CuFeO<inf>2</inf> (2.60 eV). Thus, thermoelectric and optical properties were governed by an existence of excess oxygen.
2
Some of the metrics are blocked by your
consent settings
Enhanced thermoelectric properties of Cu2Se via Sb doping: An experimental and computational study
(2023-02-01)
Rudradawong, Chalermpol
;
Khammuang, Satchakorn
;
Kotmool, Komsilp
;
Bovornratanaraks, Thiti
;
Limsuwan, Pichet
In this study, Cu<inf>2</inf>Se<inf>1−x</inf>Sb<inf>x</inf> (x = 0.000, 0.005, 0.010, and 0.015) thermoelectric materials were synthesised using a solid-state reaction technique. A first-principles calculation indicated that the formation energy of the substitution of antimony (Sb) on the Se site is negative and more stable than those of copper (Cu) sites. Sb doping enhanced the lamellar orientation, decreased the grain size, and created an acceptor impurity level. The electrical resistivity and Seebeck coefficient decreased with increasing Sb doping. A minimum reduction in the thermal conductivity by approximately three times that of the undoped sample was obtained at x = 0.005 with a value of 0.40 W/m K at 523 K. The maximum figure of merit (ZT) was obtained at x = 0.005 with a value of 0.47 at 523 K. These findings indicate that substituting Sb into Se sites is an efficient approach for improving copper selenide (Cu<inf>2</inf>Se) thermoelectric materials.
3
Some of the metrics are blocked by your
consent settings
Improvement of Thermoelectric Material by Reduction Thermal Conductivity of Sn-doped CuFeO2 Delafossite Compound
(2015-09-02)
Hongaromkij, Y.
;
Rudradawong, C.
;
Wichainchai, A.
;
Ruttanapun, C.
In this work, the polycrystalline CuFe1-xSnxO2 (x = 0.005, 0.01, 0.03) were synthesized by a solid state reaction method with sintering temperature at 1323K for 40 hours. The XRD pattern and TGA results showed the crystal structure of hexagonal delafossite-type structure for space group (166). Thermal conductivity was decreased because the large atomic mass of the Sn substituted to the Fe sites of CuFeO2. This caused phonon scattering by the point defect of the mass difference between Sn atom and Fe atom. The minimal value of the thermal conductivity was 2.1 W/mK at 573K for Sn = 0.03. © 2015
4
Some of the metrics are blocked by your
consent settings
Combined effects of Mg reducing and Sn doping on the electrical conductivity of polycrystalline Ca12Al14O33 mayenite
(2019-04-01)
Rudradawong, Chalermpol
;
Ruttanapun, Chesta
Polycrystalline Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf> was prepared by a solid state reaction method. All samples showed the phase of the Ca<inf>12</inf>Al<inf>14</inf>O<inf>33</inf> by X-ray powder diffraction (XRD). The Mg heat treatment and Sn doping contributions dominated to increase the lattice constant a from 11.909(3) to 12.163(1) Å. Electron excitation energy of all samples were assigned by absorption spectra. The excitation energy between 2.68 and 2.79 eV was found after the Mg heat treatment. Electrical conductivity increased approximately 109 orders of magnitude at room temperature when experiencing Mg heat treatment for 10 h. The highest electrical conductivity obtained from the Ca<inf>12</inf>Al<inf>12.8</inf>Sn<inf>1.2</inf>O<inf>33</inf>/Mg(10) sample was 7.65 S cm− 1 at 573 K. The low activation energy for electrical conductivity was approximately 0.038 eV as a result of the Mg heat treatment. The influence of the Sn doping excellence supported the increase of the electrical conductivity with the Mg heat treatment process.
6
Some of the metrics are blocked by your
consent settings
Stability, thermodynamic, electronic, and thermoelectric properties of triclinic Cu2Se structure
(2024-06-01)
Kotmool, Komsilp
;
Khammuang, Satchakorn
;
Rudradawong, Chalermpol
;
Thatsami, Niphat
;
Kaewmaraya, Thanayut
The conversion of heat into electricity using the thermoelectric effect is a crucial issue to tackle the ever-increasing global energy consumption. Cu<inf>2</inf>Se is one of the high-performance thermoelectric materials due to its liquid-like atomic structure, which minimizes the phonon-derived thermal conductivity. Nevertheless, the unambiguous atomic structure of the low-temperature phase, α-Cu<inf>2</inf>Se, remains controversial. By employing a combination of theoretical approaches including an evolutionary algorithm for structural searching, density functional theory, and lattice dynamics, the α-Cu<inf>2</inf>Se phase is proposed to crystalize in the dynamically stable triclinic Cu<inf>2</inf>Se structure (s.g. P1) which can be regarded as a monoclinic polymorph (s.g. P2<inf>1</inf>/c†) through slight distortion. The corresponding heat capacity (C<inf>V</inf>) and Debye temperature (Θ<inf>D</inf>) are 0.37 J/g K and 276 K, respectively, indicating low thermal conductivity in the material. The semiconducting P1 phase possesses an indirect gap of 1.0 eV. Additionally, based on the Boltzmann transportation theory, fundamental thermoelectric parameters around the transition temperature (300–500 K) are investigated. Beyond the semiconducting phase, a novel metallic phase identified as the triclinic P1̄ phase is also discovered, exhibiting a two-dimensional (2D) crystal geometry.
3
Some of the metrics are blocked by your
consent settings
High temperature electrical and thermal properties of activated bamboo charcoal/C12A7 mayenite composite prepared by carbon diffusion process
(2019-03-15)
Rudradawong, Chalermpol
;
Ruttanapun, Chesta
Activated carbon from bamboo charcoal (BC) was diffused into the C12A7 mayenite compound via carbon diffusion process for synthesizing BC and C12A7 composite (BC/C12A7 composite). The BC/C12A7 composite was fabricated by carbon diffusion at holding time 5, 10 and 20 h for investigating electrical and thermal properties at high temperature. Result of XRD revealed the C12A7 structure and confirmed by Raman spectrum. Obtained energy gap showed at 4.93, 5.26, 5.19 and 5.09 eV at holding times of 0, 5, 10 and 20 h, respectively. Electrical conductivity significantly increased with increasing temperature and increased as a function of increasing holding time. Carrier concentration showed approximately 1.27 × 10 17 , 1.32 × 10 17 and 2.76 × 10 17 cm −3 of 5, 10 and 20 h, respectively. Temperature dependence of thermal conductivity showed as proportion of T −1 due to phonon-phonon scattering of Umklapp process. The thermal conductivity decreased from pristine C12A7 approximately 0.4 W m −1 K −1 in all BC/C12A7 composite samples.
7
Some of the metrics are blocked by your
consent settings
High-performance flexible thermoelectric generator based on silicone rubber and cover with graphite sheet
(2024-01-05)
Gobpant, Jakrit
;
Klongratog, Bhanupol
;
Rudradawong, Chalermpol
;
Sakdanuphab, Rachsak
;
Junlabhut, Prasopporn
Harvesting thermal energy through a flexible thermoelectric generator (FTEG) offers an excellent micro-power solution for energizing node sensors in the realm of Internet of Things (IoT) and wearable electronics. Nonetheless, current FTEG suffer from drawbacks including low efficiency, significant thermal resistance, and complex manufacturing procedures. In this study, a high-performance FTEG using silicone rubber was designed and fabricated using a straightforward process. The finite-element method was used to optimize the copper electrode thickness, and the bendable substrate layers with various thermal conductivity were studied for the first time. The copper electrode thickness of 0.1 mm was selected because it offers high flexibility and bendability while still providing a relatively high-power output. The 5 × 5 cm2 FTEG device was fabricated and covered with a bendable substrate. Silicon rubber (0.08 Wm−1K−1), silicon rubber added 5% graphene (0.14 Wm−1K−1), and graphite sheets (15 Wm−1K−1) were used as bendable substrates. The FTEG cover with graphite sheets has a maximum output voltage of 1.1 V under a temperature difference (ΔT) at 65 °C. Its maximum output power is 162.4 mW, corresponding to a power density of 6499.1 µW/cm2 under the same above ΔT. The experimental findings indicated that integrating a bendable substrate with high thermal conductivity and electrical insulation properties enhances the performance of the FTEG.
2
Some of the metrics are blocked by your
consent settings
Method of high active preparation and electrical properties of CuFeO2 delafossite-type
(2014-01-01)
Rudradawong, Chalermpol
;
Wichainchai, Aree
;
Sakulkalavek, Aparporn
;
Hongaromkid, Yuttana
;
Ruttanapun, Chesta
In this paper, the CuFeO<inf>2</inf> compound were prepared by classical solid state reaction (CSSR) and direct powder dissolved solution (DPDS) method from starting material metal oxides and metal powders. Preparation of two methods shows that, direct powder dissolved solution faster recover phases than classical solid state reaction method. The fastest method gets from starting materials Cu and Fe metal powders, the electrical conductivity, Seebeck coefficient, carrier concentration and mobility are 10. 68 S/cm, 244. 59 μV/K, 12. 86×1016 cm-3 and 494. 96 cm2/V. s, respectively. In addition, each CuFeO<inf>2</inf> compounds were investigated on crystal structure and electrical properties. From XRD and SEM results, all samples have a crystal structure delafossitetype (R3m) and a large grain boundary more than 15 μm by electrical conductivity corresponds to grain boundary and lattice parameter: a increases. Within this paper, from above results exhibit that preparation CuFeO<inf>2</inf> from Cu and Fe by direct powder dissolved solution method most appropriate for thermoelectric oxide materials due to high active for preparation else high lattice strain and high power factor are 0. 00052 and 0. 64×10-4 W/mK2, respectively. © (2014) Trans Tech Publications, Switzerland.
1

Rudradawong, Chalermpol

Filters

Settings

Sort By

Results per page