Calculation of Effective Thermal Conductivity for Human Skin Using the Fractal Monte Carlo Method

Rojas-Altamirano, Guillermo; Vargas, René O.; Escandón, Juan P.; Mil-Martínez, Rubén; Rojas-Montero, Alan

doi:10.3390/mi13030424

Cited by 11 publications

(5 citation statements)

References 67 publications

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“…27 There are many biotissue thermodynamic models. 27 The most popular and widely used model is Pennes' heat transfer equation [28][29][30][31] :…”

Section: The Heat Generated By Muscle Cells (Q )mentioning

confidence: 99%

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Constructal design of a PCM cylindrical heat sink with three‐branched, two‐stages dendritic tubes

Ridha,

Ezzat

2024

Heat Trans

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Amputees who use prosthetic limbs suffer from the problem of high contact temperature between the socket of the prosthetic limb and the amputated part and lack of evaporation of sweat. These conditions lead to discomfort and failure to perform functions properly. In addition, these conditions help generate ulcers and accumulate harmful bacteria in this area. This paper presents a heatsink design to extract heat from the contact area. A cylindrical heat sink is designed for phase‐changing materials with three branched tubes in two stages. The current heat sink is used to cool the contact area between the amputated part and the socket in the lower prostheses. Three distributions of pipe branches are proposed. The distribution and pipe lengths were obtained using a constructal design method. In the constructal design, the lengths of the branched tubes were the degrees of freedom, the objective function was the minimization of the inlet temperature to the heat sink, and the constraint was the volume of the cylindrical heat sink. The metabolic heat transfer during exercise was estimated and its value was used to calculate the size of the cylindrical heatsink and the selection of the phase change material by testing three of them: water, tridecane, and dodecane. It was found that water gives the highest latent heat of melting and the lowest volume in addition to its availability. On the other hand, two cooling fluids were tested: water and air. It was found that water as a cooling fluid gave the lowest flow and the largest heat capacity. Constructal theory was used to design a cylindrical heat sink using branched tubes for the coolant in two steps: the first with three branches, and the second with nine branches. The degree of freedom for constructal theory was the length of the branches through the choice of their end locations. It was found that the branches of the highest length led to a reduction in temperature from 40°C to 15.48°C compared with the single tube, which reduced the temperature to 23.87°C. All tests recorded a pressure drop within the acceptable range of 3.1–5.43 Pa for the branches examined. The research demonstrated that using constructal theory achieved the best thermal dissipation within a restricted volume.

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“…27 There are many biotissue thermodynamic models. 27 The most popular and widely used model is Pennes' heat transfer equation [28][29][30][31] :…”

Section: The Heat Generated By Muscle Cells (Q )mentioning

confidence: 99%

“…44 It is fitted polynomially for using in the calculation to k T T = −0.0097 + 2.1515 + 557.48. 2 (31) The flow velocity U in Equation ( 30) is from…”

Section: Pcmmentioning

confidence: 99%

Constructal design of a PCM cylindrical heat sink with three‐branched, two‐stages dendritic tubes

Ridha,

Ezzat

2024

Heat Trans

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“…Yu et al applied MC simulation to obtain the permeability of bidispersed fractal porous media. In addition, fractal Monte Carlo method (FMC) has also been used in shale gas flow, two-phase flow, − fractured porous media, , and other fields. − The different models with their limitations proposed by previous researchers are summarized in Table . Nevertheless, it has not been reported that the FMC method is applied to simulate liquid transport in shale formation while considering the effective slip effect and varying viscosity of the confined fluid, which will be the focused point of our study.…”

Section: Introductionmentioning

confidence: 99%

Investigations of Water Transport in Shale Reservoir with Dual-Wettability by Using Monte Carlo Method

Liang,

Fan,

et al. 2023

ACS Omega

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How liquids transport in the shale system has been the focus because of fracturing fluid loss. In this study, a single-nanopore model is established for liquid transport in shale while considering the slip effect and effective viscosity of confined fluids. Then, the fractal Monte Carlo (FMC) model is proposed to upscale the single-pore model into shale porous media. The effects of different transport mechanisms, shale wettability, and pore characteristic parameters on confined liquid flow in shale rock are investigated. Results show that FMC permeabilities are 2–3 orders of magnitude larger than intrinsic and slip-corrected permeabilities in organic matter. However, the slip effect and effective viscosity have little influence on water flow in inorganic matter. With the contact angle of organic pore (θ om ) increasing and contact angle of inorganic pore (θ in ) decreasing, the effective permeability of the whole shale matrix grows in number. The enhancement factor in the situation of θ om = 170° and θ in = 20° is 4 orders of magnitude larger than the case of θ om = 130° and θ in = 40°, although the close effective macroscopic contact angle (θ eff = 80°) occurs in these two cases, which indicates that shale microscopic wettability has a significant impact on the confined liquid transport. Moreover, with the increase of porosity and maximum pore diameters, shale permeability increases rapidly, but the enhancement factor has the opposite trend. Compared with the tiny impact of the variance of minimum inorganic pore diameters, minimum organic pore diameters have more significant impacts on liquid flow in shale systems, and the enhancement factor also rapidly increases up to 30 times for the case of 0.5 nm because of the strong slip effect.

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“…In contrast, the key components of organ-based physiological thermoregulation have undergone significant studies, and current studies focus on examining their intricate connections at the cellular and molecular levels. [2][3][4][5][6][7][8][9][10][11][12][13] To maintain body temperature homeostasis under changing conditions in the external or internal environment, macroscopic organisms should differ in their k of the body. [3,13] There are facts and observations that implicitly suggest genetic variability in the k of the body in humans: 1.…”

Section: Introductionmentioning

confidence: 99%

Untitled

2023

AJP

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Background: According to physicists, thermal conductivity (k) refers to the rate at which thermal energy and the interaction of microparticles transfer energy from warmer to colder parts of the body. To maintain body temperature homeostasis under changing conditions in the external or internal environment, macroscopic organisms should differ in their k of the body. The objective of the study is to evaluate the k of the body in students from Kyrgyzstan, India, and China. Materials and Methods: In this study, 600 students from various racial and ethnic groups attended institutions in Bishkek, Kyrgyzstan, including 200 students from each of the following groups: Kyrgyz, Indian, and Chinese. The Kyrgyz and Indian (Uttar Pradesh and Punjab, India) students from the Kyrgyz State Medical Academy, the International Higher School of Medicine, and the Chinese (Guangzhou Province, China) students from the Kyrgyz Pedagogical University in Bishkek, Kyrgyzstan, were studied to determine if race or ethnicity could affect the k of the body. Results: There were significant differences between the values of k among the students of India and China, Kyrgyzstan and China, while the alleged relationship between Indians and Kyrgyz did not appear which indicates a possible similarity between the k of the bodies of two nationalities. Conclusion: Variation was observed in the k of various national groups in comparison to one another. The Kyrgyz and Indian students have a similar distribution of k values, but the Chinese students have a distinct pattern.

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Calculation of Effective Thermal Conductivity for Human Skin Using the Fractal Monte Carlo Method

Cited by 11 publications

References 67 publications

Constructal design of a PCM cylindrical heat sink with three‐branched, two‐stages dendritic tubes

Constructal design of a PCM cylindrical heat sink with three‐branched, two‐stages dendritic tubes

Investigations of Water Transport in Shale Reservoir with Dual-Wettability by Using Monte Carlo Method

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