A three-dimensional conjugate heat transfer model for thermal protective clothing

Udayraj,; Wang, Faming

doi:10.1016/j.ijthermalsci.2018.04.005

Cited by 34 publications

(17 citation statements)

References 25 publications

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“…According to the literatures, most of the numerical models ignored the convective heat transfer in the microclimate (Ghazy, 2014; Ghazy and Bergstrom, 2010, 2012), but the importance of the convection has been stated on the bench scale (Torvi, 1997). As indicated by Udayraj et al (2018), neglecting convection in the microclimate affected heat transfer and significantly overestimated the thermal protection of the fabric for thicker horizontal air gap and overestimated the thermal protection for all widths of vertical gaps. According to our research on garment level, the heat transfer modes were more complicated, which were significantly affected by the ventilation openings and related to the exposure durations and heat intensities.…”

Section: Resultsmentioning

confidence: 94%

Heat transfer modeling within the microclimate between 3D human body and clothing: effects of ventilation openings and fire intensity

Tian

2020

IJCST

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PurposeThe purpose of this study is to determine the effect of ventilation openings and fire intensity on heat transfer and fluid flow within the microclimate between 3D human body and clothing.Design/methodology/approachOn account of interaction effects of fire and ventilation openings on heat transfer process, a 3D transient computational fluid dynamics model considering the real shape of human body and clothing was developed. The model was validated by comparing heat flux history and distribution with experimental results. Heat transfer modes and fluid flow were investigated under three levels of fire intensity for the microclimate with ventilation openings and closures.FindingsTemperature distribution on skin surface with open microclimate was heavily depended on the heat transfer through ventilation openings. Higher temperature for the clothing with confined microclimate was affected by the position and direction of flames injection. The presence of openings contributed to the greater velocity at forearms, shanks and around neck, which enhanced the convective heat transfer within microclimate. Thermal radiation was the dominant heat transfer mode within the microclimate for garment with closures. On the contrary, convective heat transfer within microclimate for clothing with openings cannot be neglected.Practical implicationsThe findings provided fundamental supports for the ease and pattern design of the improved thermal protective systems, so as to realize the optimal thermal insulation of the microclimate on the garment level in the future.Originality/valueThe outcomes broaden the insights of results obtained from the mesoscale models. Different high skin temperature distribution and heat transfer modes caused by thermal environment and clothing structure provide basis for advanced thermal protective clothing design.

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Section: Resultsmentioning

confidence: 94%

Heat transfer modeling within the microclimate between 3D human body and clothing: effects of ventilation openings and fire intensity

Tian

2020

IJCST

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“…In formula (4), k 5 is the effective thermal conductivity of the outer garment (a mixture of clothing fiber and air), which is calculated according to the effective medium theory 24 :…”

Section: A 3d Analysis Model For Heat Conduction Between Skin and Fabricsmentioning

confidence: 99%

“…Cui et al [21][22][23] had developed the flexible electronic heating equipment combined with skin metabolic heat production, which was used for one-dimensional (1D) and 3D heat conduction analysis to explore the influence of the size, load, and material of the flexible electronic heating equipment on its heat transfer. Udayraj and Wang 24,25 established a 3D heat transfer model to analyze the heat transfer of thermal protective clothing under radiation heat exposure. A computational fluid dynamics model was used to analyze the heat transfer of the air gap between clothing and skin.…”

Section: Introductionmentioning

confidence: 99%

Three-dimensional analysis model of electric heating fabrics considering the skin metabolism

Xiao

Kuai

et al. 2021

Journal of Engineered Fibers and Fabrics

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In low temperature environment, electric heating clothing can provide extra heat for human body through built-in heat source, so it has better thermal insulation effect. The thermal analysis is the initial step for electric heating clothing design. The current thermal analysis of electric heating textiles focuses on the fabric itself instead of the effect of skin tissue metabolism and heat production. In order to improve the accuracy of skin surface temperature prediction, the biological heat transfer need be modeled to analyze the internal temperature distribution of the heating suit system. In this paper, a three-dimensional (3D) thermal analysis model of electric heating clothing combined with human skin tissue is established. Firstly, the coupling analysis of Fourier heat conduction and Pennes biological heat transfer equation is carried out. Then the reliability of the 3D thermal analysis model is verified by finite element analysis (FEA). The results show that the fitting error between the three-dimensional model analysis data and FEA simulation data is 5°C, which proves that the model can accurately predict the system temperature. Finally, we make further research about the effects of ambient temperature, clothing layer thickness, and input power on the maximum skin surface temperature. This study provides theoretical foundation for the design of wearable thermal management fabric.

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“…In recent five years, this numerical method has been widely used. Li (2017, 2019), Udayraj et al (2017a, b), Udayraj and Wang (2018), Wang et al (2015) also tried to develop the numerical model of clothed manikin and the heat transfer model of the air gap by using CFD technology. However, at present, the application of CFD technology is mainly focused on the simulation of thermal protective fabric-air gap-human skin surface, and there is little information on the heat transfer process inside of the human skin and inside of the thermal sensor.…”

Section: Introductionmentioning

confidence: 99%

Development and application of numerical model of thermal sensors for thermal protective clothing evaluation based on CFD simulation

Tang

Mao

et al. 2022

IJCST

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PurposeThe purpose of this paper is to study the heat transfer effect of copper sensor and skin simulant on skin.Design/methodology/approachFor the sensor, the physical and mathematical models of the thermal sensors were used to obtain the definite conditions in the heat transfer process of the sensor, and the heat transfer models of the two sensors were developed and solved respectively by using ANSYS WORKBENCH 19.0 software. The simulation results were compared with the experimental test results. For the skin, the numerical model of the skin model was developed and calculated. Finally, the heat transfer simulation performance of the two sensors was analyzed.FindingsIt is concluded that the copper sensor is more stable than the skin simulant, but the material and structure of the skin simulant is more suitable for skin simulation. The skin simulant better simulates the skin heat transfer. For all the factors in the model, the thermal properties of the material and the heat flux level are the key factors. The convective heat transfer coefficient, radiation heat transfer rate and the initial temperature have little influence on the results, which can be ignored.Research limitations/implicationsThe results show that there are still some differences between the experimental and numerical simulation values of the skin simulant. In the future, the thermal parameters of skin simulant and the influence of the thermocouple adhesion should be further examined during the calibration process.Practical implicationsThe results suggest that the skin simulant needs to be further calibrated, especially for the thermal properties. The copper sensor on the flame manikin can be replaced by the skin simulant with higher accuracy, which will be helpful to improve the accuracy of performance evaluation of thermal protective clothing.Social implicationsThe application of computational fluid dynamics (CFD) technology can help to analyze the heat transfer simulation mechanism of thermal sensor, explore the influence of thermal performance of thermal sensor on skin simulation, provide basis for the development of thermal sensor and improve the application system of thermal sensor. Based on the current research status, this paper studies the internal heat transfer of the sensor through the numerical modeling of the copper sensor and skin simulant, so as to analyze the effect of the sensor simulating skin and the reasons for the difference.Originality/valueIn this paper, the sensor itself is numerically modeled and the heat transfer inside the sensor is studied.

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A three-dimensional conjugate heat transfer model for thermal protective clothing

Cited by 34 publications

References 25 publications

Heat transfer modeling within the microclimate between 3D human body and clothing: effects of ventilation openings and fire intensity

Heat transfer modeling within the microclimate between 3D human body and clothing: effects of ventilation openings and fire intensity

Three-dimensional analysis model of electric heating fabrics considering the skin metabolism

Development and application of numerical model of thermal sensors for thermal protective clothing evaluation based on CFD simulation

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