scholarly journals ANALYSIS OF THE THERMOPHYSICAL PROPERTIES AND INFLUENCING FACTORS OF VARIOUS ROCK TYPES FROM THE GUIZHOU PROVINCE

2018 ◽  
Vol 53 ◽  
pp. 03059 ◽  
Author(s):  
Song Xiaoqing ◽  
Jiang Ming ◽  
Xiong Peiwen
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Diffusion Coefficient ◽  
Specific Heat ◽  
Thermal Diffusion ◽  
Specific Heat Capacity ◽  
Thermophysical Properties ◽  
Guizhou Province ◽  
Thermal Diffusion Coefficient ◽  
Rock Types

A series of analyses have been carried out on a number of rock types from the Guizhou Province to investigate their thermophysical properties. A total of 433 samples from 14 types of rock were collected, tested and analyzed. It was found that in this province, the average thermal conductivity of the samples ranged between 1.516±0.264 and 5.066±0.521 W/(m·K), the average specific heat capacity varied from 0.272±0.042 to 0.603±0.096 kJ/(kg·°C), and the average thermal diffusion coefficients were from 0.752±0.331 to 2.854±0.368 MJ/(m3·K). The older rocks always had higher thermal conductivity and thermal diffusion. Thermal conductivity and thermal diffusion of rocks are positively correlated with the mineral content of high thermal conductivity species, but the situation for the specific heat capacity is the opposite. With increasing mineral particle size, the thermal conductivity and thermal diffusion coefficient also increase, but the relationship with specific heat capacity is not obvious. The thermal conductivity and thermal diffusion coefficient of rocks increases under water saturated conditions compared to dry conditions, but the specific heat capacity decreases.

Study and Analysis of Metal Coolant Thermophysical Properties

2012 ◽  
Vol 184-185 ◽  
pp. 1226-1231
Author(s):  
Meng Ying Liu ◽  
Tao Zhou ◽  
Wen Zhong Zou ◽  
Zi Wei Su
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Thermophysical Properties ◽  
Kinematic Viscosity ◽  
Fusion Reactor ◽  
Small Difference ◽  
Heat Transfer Capacity ◽  
Metal Coolant

The article chooses Na, LiPb and LBE three kinds of metal coolant, and makes a comparative analysis of the thermophysical properties of Na, LiPb and LBE when they are at liquid state. The results show that Na has the lowest density and the largest thermal conductivity and specific heat capacity. There is a small difference between LBE and LiPb in terms of density, thermal conductivity and specific heat capacity. LiPb has the largest kinematic viscosity. The thermal conductivity of Na decreases as temperature rises, which is opposite of LBE and LiPb. The kinematic viscosity of LiPb increases as temperature rises. Considering thermal conductivity and specific heat capacity, LBE and LiPb are not the best coolant. However, their high densities can economize equipments and materials at the same time. When it flows, LiPb’s heat transfer capacity gets larger as temperature rises, this character can not be ignored in fusion reactor.

scholarly journals Thermophysical Properties of Larch Bark Composite Panels

Polymers ◽  
2021 ◽  
Vol 13 (14) ◽  
pp. 2287
Author(s):  
Lubos Kristak ◽  
Ivan Ruziak ◽  
Eugenia Mariana Tudor ◽  
Marius Cătălin Barbu ◽  
Günther Kain ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Particle Size ◽  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Thermophysical Properties ◽  
Urea Formaldehyde ◽  
Raw Material ◽  
Particle Orientation ◽  
Thermal Resistivity

The effects of using 100% larch bark (Larix decidua Mill) as a raw material for composite boards on the thermophysical properties of this innovative material were investigated in this study. Panels made of larch bark with 4–11 mm and 10–30 mm particle size, with ground bark oriented parallel and perpendicular to the panel’s plane at densities varying from 350 to 700 kg/m3 and bonded with urea-formaldehyde adhesive were analyzed for thermal conductivity, thermal resistivity and specific heat capacity. It was determined that there was a highly significant influence of bulk density on the thermal conductivity of all the panels. With an increase in the particle size, both parallel and perpendicular to the panel´s plane direction, the thermal conductivity also increased. The decrease of thermal diffusivity was a consequence of the increasing particle size, mostly in the parallel orientation of the bark particles due to the different pore structures. The specific heat capacity is not statistically significantly dependent on the density, particle size, glue amount and particle orientation.

scholarly journals Study on Thermophysical Properties of a Lead–Bismuth-Based Graphene Nanofluid

2021 ◽  
Vol 9 ◽  
Author(s):  
Tao Yang ◽  
Pengcheng Zhao ◽  
Qiong Li ◽  
Yanan Zhao ◽  
Tao Yu
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Thermophysical Properties ◽  
Prediction Models ◽  
Reactor Core ◽  
Engineering Application ◽  
Nanoparticle Suspension ◽  
Graphene Nanoparticles

Incorporating graphene nanoparticles with high thermal conductivity into a lead-based coolant can significantly increase its thermal conductivity and specific heat capacity, thereby increasing the core power density of lead–bismuth cooled reactors, reducing the amount of coolant required, and ultimately realizing a miniaturized and lightweight reactor design. The purpose of the design is of great significance to the engineering application of lead–bismuth stacks in remote areas and open seas. In this study, the thermophysical properties of metal-based graphene nanofluids are analyzed by comparing and analyzing prediction models established for the thermal conductivity, viscosity, and specific heat capacity. The strengthening mechanism of nanofluids is summarized, and a series of suitable calculation formulae for the thermophysical properties of lead–bismuth-based graphene nanofluids is proposed. The research results show that incorporating graphene nanoparticles into a lead–bismuth-based coolant can significantly improve its thermal conductivity and specific heat capacity. When the nanoparticle suspension is relatively stable, the thermal conductivity, specific heat capacity, and viscosity increase significantly with the concentration of graphene nanoparticles. When the concentration reaches 20%, the thermal conductivity and specific heat capacity of the nanofluid are enhanced by approximately 80 and 20%, respectively, whereas the viscosity is also increased by approximately 100%. Therefore, it is important to appropriately select the parameters for the addition of nanoparticles to maximize the effect of lead–bismuth-based graphene nanofluids on the heat transfer performance of the reactor core.

Thermophysical Properties of Steam–Air Under High Temperature and High Pressure

2019 ◽  
Vol 142 (4) ◽  
Author(s):  
Zhengbin Wu ◽  
Shu Jiang ◽  
Lei Wang ◽  
Yiguo Zhang
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
High Pressure ◽  
High Temperature ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Heavy Oil ◽  
Thermophysical Properties ◽  
Steam Injection ◽  
Steam System

Abstract Air-assisted steam injection is a new technique for heavy oil reservoir exploitation. This paper focused on the thermophysical properties of the air/steam system, such as density, viscosity, specific heat capacity, enthalpy, and thermal conductivity coefficient, and these have been calculated using the Redlich–Kwong equation of state (RK EOS). The viscosity of the air/steam system under high temperature and high pressure was calculated with the corresponding state principle and rectified with the Dean–Stiel residual viscosity method. The results showed that compared with the saturated steam of the same mass, the viscosity, specific heat capacity, thermal conductivity, and enthalpy of the air/steam mixture decreased, while the specific volume increased, which indicated that the addition of air to steam weakened the thermal effect of the steam and makes use of the heat insulation and thermal expansion of air. This study can provide guidance for parameter design of air-assisted steam injection for heavy oil recovery.

Experimental Study on the Specific Heat Capacity Measurement of Water-Based Al2O3-Cu Hybrid Nanofluid by using Differential Thermal Analysis Method

2019 ◽  
Vol 15 ◽  
Author(s):  
Andaç Batur Çolak ◽  
Oğuzhan Yıldız ◽  
Mustafa Bayrak ◽  
Ali Celen ◽  
Ahmet Selim Dalkılıç ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Thermophysical Properties ◽  
Volume Concentration ◽  
Pure Water ◽  
Heat Capacity Measurement ◽  
Experimental Results ◽  
Hybrid Nanofluid ◽  
Capacity Measurement

Background: Researchers working in the field of nanofluid have done many studies on the thermophysical properties of nanofluids. Among these studies, the number of studies on specific heat are rather limited. In the study of the heat transfer performance of nanofluids, it is necessary to increase the number of specific heat studies, whose subject is one of the important thermophysical properties. Objective: The authors aimed to measure the specific heat values of Al2O3/water, Cu/water nanofluids and Al2O3-Cu/water hybrid nanofluids using the DTA method, and compare the results with those frequently used in the literature. In addition, this study focuses on the effect of temperature and volume concentration on specific heat. Method: The two-step method was used in the preparation of nanofluids. The pure water selected as the base fluid was mixed with the Al2O3 and Cu nanoparticles and Arabic Gum as the surfactant, firstly mixed in the magnetic stirrer for half an hour. It was then homogenized for 6 hours in the ultrasonic homogenizer. Results: After the experiments, the specific heat of nanofluids and hybrid nanofluid were compared and the temperature and volume concentration of specific heat were investigated. Then, the experimental results obtained for all three fluids were compared with the two frequently used correlations in the literature. Conclusion: Specific heat capacity increased with increasing temperature, and decreased with increasing volume concentration for three tested nanofluids. Cu/water has the lowest specific heat capacity among all tested fluids. Experimental specific heat capacity measurement results are compared by using the models developed by Pak and Cho and Xuan and Roetzel. According to experimental results, these correlations can predict experimental results within the range of ±1%.

scholarly journals Influence of alkaline modification on selected properties of banana fiber paperbricks

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Abayomi A. Akinwande ◽  
Adeolu A. Adediran ◽  
Oluwatosin A. Balogun ◽  
Oluwaseyi S. Olusoju ◽  
Olanrewaju S. Adesina
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Moisture Absorption ◽  
Water Volume ◽  
Banana Fiber ◽  
Fiber Loading ◽  
Banana Fibers ◽  
Alkaline Modification

AbstractIn a bid to develop paper bricks as alternative masonry units, unmodified banana fibers (UMBF) and alkaline (1 Molar aqueous sodium hydroxide) modified banana fibers (AMBF), fine sand, and ordinary Portland cement were blended with waste paper pulp. The fibers were introduced in varying proportions of 0, 0.5, 1.0 1.5, 2.0, and 2.5 wt% (by weight of the pulp) and curing was done for 28 and 56 days. Properties such as water and moisture absorption, compressive, flexural, and splitting tensile strengths, thermal conductivity, and specific heat capacity were appraised. The outcome of the examinations carried out revealed that water absorption rose with fiber loading while AMBF reinforced samples absorbed lesser water volume than UMBF reinforced samples; a feat occasioned by alkaline treatment of banana fiber. Moisture absorption increased with paper bricks doped with UMBF, while in the case of AMBF-paper bricks, property value was noted to depreciate with increment in AMBF proportion. Fiber loading resulted in improvement of compressive, flexural, and splitting tensile strengths and it was noted that AMBF reinforced samples performed better. The result of the thermal test showed that incorporation of UMBF led to depreciation in thermal conductivity while AMBF infusion in the bricks initiated increment in value. Opposite behaviour was observed for specific heat capacity as UMBF enhanced heat capacity while AMBF led to depreciation. Experimental trend analysis carried out indicates that curing length and alkaline modification of fiber were effective in maximizing the properties of paperbricks for masonry construction.

The Key Factors of Low-Frequency Electric Heating Assisted Depressurization Method in the Exploiting of Methane Hydrate Sediments

2021 ◽  
Author(s):  
Ermeng Zhao ◽  
Jian Hou ◽  
Yunkai Ji ◽  
Lu Liu ◽  
Yongge Liu ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Low Frequency ◽  
Electric Heating ◽  
Gas Production ◽  
Hydrate Decomposition ◽  
Hydrate Saturation ◽  
Production Behavior

Abstract Natural gas hydrate is widely distributed in the permafrost and marine deposits, and is regarded as an energy resource with great potential. The low-frequency electric heating assisted depressurization (LF-EHAD) has been proven to be an efficient method for exploiting hydrate sediments, which involves complex multi-physics processes, i.e. current conduction, multiphase flow, chemical reaction and heat transfer. The physical properties vary greatly in different hydrate sediments, which may profoundly affect the hydrate decomposition in the LF-EHAD process. In order to evaluate the influence of hydrate-bearing sediment properties on the gas production behavior and energy utilization efficiency of the LF-EHAD method, a geological model was first established based on the data of hydrate sediments in the Shenhu Area. Then, the influence of permeability, porosity, thermal conductivity, specific heat capacity, hydrate saturation and hydrate-bearing layer (HBL) thickness on gas production behavior is comprehensively analyzed by numerical simulation method. Finally, the energy efficiency ratio under different sediment properties is compared. Results indicate that higher gas production is obtained in the high-permeability hydrate sediments during depressurization. However, after the electric heating is implemented, the gas production first increases and then tends to be insensitive as the permeability decreases. With the increasing of porosity, the gas production during depressurization decreases due to the low effective permeability; while in the electric heating stage, this effect is reversed. High thermal conductivity is beneficial to enhance the heat conduction, thus promoting the hydrate decomposition. During depressurization, the gas production is enhanced with the increase of specific heat capacity. However, more heat is consumed to increase the reservoir temperature during electric heating, thereby reducing the gas production. High hydrate saturation is not conducive to depressurization because of the low effective permeability. After electric heating, the gas production increases significantly. High HBL thickness results in a higher gas production during depressurization, while in the electric heating stage, the gas production first increases and then remains unchanged with the increase of thickness, due to the limited heat supply. The comparison results of energy efficiency suggest that electric heating is more advantageous for hydrate sediments with low permeability, high porosity, high thermal conductivity, low specific heat capacity, high hydrate saturation and high HBL thickness. The findings in this work can provide a useful reference for evaluating the application of the LF-EHAD method in gas hydrate sediments.

Determination of the Thermal Properties of a PCB by Coupled Numerical and Experimental Approach

2020 ◽  
Author(s):  
Yener Usul ◽  
Mustafa Özçatalbaş
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Numerical Analysis ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Thermal Analyses ◽  
Analysis Model ◽  
Linear Temperature ◽  
Coefficient Of Thermal Conductivity

Abstract Increasing demand for usage of electronics intensely in narrow enclosures necessitates accurate thermal analyses to be performed. Conduction based FEM (Finite Element Method) is a common and practical way to examine the thermal behavior of an electronic system. First step to perform a numerical analysis for any system is to set up the correct analysis model. In this paper, a method for obtaining the coefficient of thermal conductivity and specific heat capacity of a PCB which has generally a complex composite layup structure composed of conductive layers, and dielectric layers. In the study, above mentioned properties are obtained performing a simple nondestructive experiment and a numerical analysis. In the method, a small portion of PCB is sandwiched from one side at certain pressure by jaws. A couple of linear temperature profiles are applied to the jaws successively. Unknown values are tuned in the analysis model until the results of FEM analysis and experiment match. The values for the coefficient of thermal conductivity and specific heat capacity which the experiment and numerical analysis results match can be said to be the actual values. From this point on, the PCB whose thermal properties are determined can be analyzed numerically for any desired geometry and boundary condition.

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