Study on dynamic thermal control performance of positive temperature coefficient (PTC) material based on a novel heat transfer model considering internal heat transfer

Wang, Ruo-Jiang; Pan, Yong; Nian, Yong‐Le; Cheng, Wen‐Long

doi:10.1016/j.applthermaleng.2019.114452

Cited by 18 publications

(6 citation statements)

References 26 publications

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“…where P is the heat energy provided by the electric heating cable per unit length (kW/m); L is the length of the electric heating cable, m; β s is the equivalent convective heat release coefficient; A is a solid surface in the air (m 2 ); T ∞ is the temperature of the fluid around the boundary surface ( Test system: To consider the effect of curing temperature on concrete strength, a relationship between the compressive strength and equivalent age te is shown in Equation (2). A heating process was designed based on the theory of equivalent ages [29,30].…”

Section: ( )mentioning

confidence: 99%

“…The resistivity of the material increases rapidly to 103-109 times its initial value when the temperature exceeds a specific threshold [1]. Based on the energy control features of PTC materials, the electric heating materials automatically limit the temperature during heating by adjusting output power in accordance with changes in system temperature [2,3]. The heating core of a selflimiting temperature electric heating system consists of a polymer-conductive composite material made of a polymer matrix doped with conductive materials such as carbon black or graphite to form a heating element [4,5], as shown in Figure 1a.…”

Section: Introductionmentioning

confidence: 99%

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Evolution and Parametric Analysis of Concrete Temperature Field Induced by Electric Heating Curing in Winter

Han,

Liu,

Zuo

et al. 2023

Sustainability

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Electric heat treatment is a widely used concrete curing method during the winter. Through direct and indirect heat exchange, the electric heating system tracks and controls the temperature of the heating medium based on a positive temperature coefficient (PTC) effect. In this study, to standardize the application of this treatment in the winter curing of concrete, the thermal energy conversion of an electric heating system and the heat-transfer characteristics of concrete have been studied. Based on the theoretical derivation, a calculation model of the relationship between the thermal energy of the electric heating system and the temperature of the concrete is established. The model is verified using the concrete heating and curing test results. The numerical analysis program COMSOL is used to analyze the effects of various factors on the concrete temperature field, including the electric heating power (e.g., the surface temperature of the electric heating system), concrete casting temperature, thermal conductivity, and heat release coefficient. The results show that decreasing the surface exothermic coefficient and increasing the heating temperature will significantly increase the peak temperature of the concrete. When the heat source temperature increases by 20 °C, the peak temperature could increase by approximately 13 °C. When the heating stops, the concrete volume increases temporarily, particularly in the region where the heating cable is buried. Consequently, an excessive heating power increase may cause cracks on the concrete surface. Compared with the factors of thermal conductivity and surface exothermic coefficient, the ambient temperature has the most significant effect on the concrete cooling rate when the heating stops. When the ambient temperature decreases by −20 °C, the cooling rate of concrete increases by 0.72 °C/h. The role of concrete insulation materials needs to be strengthened to reduce cooling rates during power outages and form removal. The findings from the study provide industry practitioners with a comprehensive guide regarding the specific applications of the electric heating system in early-age concrete curing.

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Section: ( )mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evolution and Parametric Analysis of Concrete Temperature Field Induced by Electric Heating Curing in Winter

Han,

Liu,

Zuo

et al. 2023

Sustainability

View full text Add to dashboard Cite

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“…Cheng WL et al proposed some PTC materials based on C 24 H 50 /LDPE/GP and so on, with the Curie temperature of around 25 C and investigated their adaptive temperature control performance. [18][19][20] These works present a shape-stable PTC material with prominent resistivitytemperature coefficient and Curie points in the room temperature region. However, it is noteworthy that the conventional sphere-like conductive particles such as graphite and carbon black (CB) are introduced to these composites to construct conductive pathways.…”

Section: Introductionmentioning

confidence: 99%

Fabrication and performance evaluation of the flexible positive temperature coefficient material for self‐regulating thermal control

et al. 2023

J of Applied Polymer Sci

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In this study, three kinds of newly flexible positive temperature coefficient (PTC) materials are fabricated by a simple preparation method. Due to introducing the hybrid filler of carbon nanotube and carbon black, these materials exhibit remarkable PTC effect including the PTC intensity of more than four‐orders magnitude and the resistivity‐temperature coefficient of 154%/°C. The Curie points of PTC materials are regulated to room‐temperature range by the low melting phase and influenced by melting onset temperatures of their solid–liquid phase change. With the help of transmission electron microscope, the micro‐capsule structure of the phase change regions is observed, and the hybrid conductive fillers randomly distribute in the blend matrix to construct three‐dimensional conductive network. Using the PTC materials as a heating element, the equilibrium temperature of the controlled device can be maintained around their Curie point without any control method. Moreover, the adaptive thermal control effect becomes more obvious with the increase of ambient temperature and initial heating power. Furthermore, the thermal control accuracy fluctuates within 0.15°C without any external control method, and is improved to round 0.08°C in combination with the switch control method. This study provides a new method for the thermal control of electronic devices in the requirement of lightweight and miniaturization at low temperature environment.

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“…Currently, there are two common heating systems for electric vehicles, namely the positive temperature coefficient (PTC) thermistor heating system and the heat pump heating system. Experimental studies have shown that the PTC heating system can meet the requirements of defogging and defrosting in low temperature environment and heating in winter [4]. However, this heating system has the disadvantage of low efficiency [5,6].…”

Section: Introductionmentioning

confidence: 99%

Numerical study on flow and heat transfer performance of serpentine parallel flow channels in a high voltage heater system

et al. 2022

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In this study, a high-voltage heater system with a size of 310 mm ? 210 mm ? 60 mm has been numerically studied and experimentally verified to explore the influence of the cavity structure on the flow and heat transfer performance. the response surface model and analysis of variance are used to determine the influence of the length of the mainstream area of the inlet (Lin), the length of the mainstream area of the outlet (Lout), the length of the parallel flow channel (Lch) and the single channel width (W) on the flow heat transfer, and ultimately find the best structural plan. The results show that the structural parameters of the parallel flow channel are significantly more important than those of the mainstream area, with the width and length of the parallel single channel being the primary and secondary structural parameters, respectively. The optimization scheme obtained by the NGSA-II algorithm can simultaneously meet the requirements of heat transfer and flow uniformity. Specifically, compared with the original model, the flow distribution uniformity coefficient (S) and the inlet/outlet pressure drop (Ptotal) decreased by 53.49 and 19.52%, respectively, while the average heat transfer coefficient increased by 28.05%.

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Study on dynamic thermal control performance of positive temperature coefficient (PTC) material based on a novel heat transfer model considering internal heat transfer

Cited by 18 publications

References 26 publications

Evolution and Parametric Analysis of Concrete Temperature Field Induced by Electric Heating Curing in Winter

Evolution and Parametric Analysis of Concrete Temperature Field Induced by Electric Heating Curing in Winter

Fabrication and performance evaluation of the flexible positive temperature coefficient material for self‐regulating thermal control

Numerical study on flow and heat transfer performance of serpentine parallel flow channels in a high voltage heater system

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