Thermophysical Properties of Baled Switchgrass

2021 ◽  
Vol 37 (6) ◽  
pp. 1107-1114
Author(s):  
Drew F Schiavone ◽  
Michael D Montross
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Multiple Regression ◽  
Thermophysical Properties ◽  
Material Properties ◽  
Thermal Probe ◽  
Transfer Rates ◽  
Thermophysical Parameters

HighlightsThermal conductivity and thermal diffusivity of baled switchgrass were measured with a dual thermal probe.Specific heat of baled switchgrass was estimated based on other thermophysical parameters.Thermophysical parameters were modeled as functions of the material properties using multiple regression.Anisotropism was observed with different heat transfer rates occurring in each directional orientation.Abstract.Although the thermophysical properties of baled biomass play a critical role in developing postharvest quality models, these parameters have not been investigated for many bulk agricultural feedstocks including switchgrass. In this study, a dual thermal probe, consisting of a thermal conductivity probe and separate thermal diffusivity probe, was used to determine the thermal conductivity, thermal diffusivity, and specific heat of lab-scale rectangular bales of switchgrass (~10.16 × 10.16 × 30.48 cm). Thermal conductivity, thermal diffusivity, and specific heat ranged from 1.04E-2 to 6.10E-2 W m-1 °C-1, 0.863E-7 to 2.284E-7 m2 s-1, and 0.40 to 2.51 kJ kg-1 °C-1, respectively, depending on temperature (20.3°C, 30.2°C, and 40.1°C), moisture content (11.4%, 20.8%, 29.0%, and 42.3% on a wet basis), bulk density (157.2, 172.4, 197.2, and 230.1 kg m-3) and directional orientation (lateral or transverse). The results of this study promote a practical understanding of heat transfer within baled switchgrass while defining the dynamic relationship to material properties through multiple regression analysis. Anisotropism between the lateral and transverse bale orientations was observed with different heat transfer rates observed in both directional orientations. This anisotropism was attributed to the unique physical composition of the bulk material in the axial direction of bale compression (i.e., variation in porosity, discontinuous porous cavities, and material heterogeneity) compared to the composition of continuous stem material forming a layered flake of the rectangular bale. Keywords: Biomass, Bioprocessing, High solids, Thermal conductivity, Thermal diffusivity.

Thermophysical Properties of Germanium for Thermal Analysis of Growth from the Melt

1981 ◽  
Vol 9 ◽  
Author(s):  
Roger K. Crouch ◽  
A. L. Fripp ◽  
W. J. Debnam ◽  
R. E. Taylor ◽  
H. Groot
Keyword(s):  
Thermal Conductivity ◽  
Thermal Analysis ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Thermophysical Properties ◽  
Room Temperature ◽  
Bridgman Method ◽  
The Other ◽  
Temperature Range ◽  
Diffusivity Measurements

ABSTRACTThe thermal diffusivity of Ge has been measured over a temperature range from 300° C to 1010° C which includes values for the melt. Specific heat has been measured from room temperature to 727° C. Thermal conductivity has been calculated over the same temperature range as the diffusivity measurements. These data are reported along with the best values from the literature for the other parameters which are required to calculate the temperature and convective fields for the growth of germanium by the Bridgman method. These parameters include the specific heat, the viscosity, the emissivity, and the density as a function of temperature.

scholarly journals Determination of thermophysical properties of cupuassu (Theobroma grandiflorum) dry almonds

2021 ◽  
Vol 7 (2) ◽  
Author(s):  
Elisa Santana Cunha ◽  
Geovana Pires Araújo Lima ◽  
Jorge Henrique Oliveira Sales ◽  
Elizama Aguiar de Oliveira
Keyword(s):  
Thermal Conductivity ◽  
Activation Energy ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Thermophysical Properties ◽  
Effective Diffusivity ◽  
Theobroma Grandiflorum

In comparison to cocoa, little has been reported on the drying of cupuassu almonds that can be used to produce cupulate, a chocolate type product. Thus, in this study thermophysical properties of cupuassu dry almonds (moisture = 9.68 % d.b.) were determined as: thermal conductivity (k) of 0.14 kW/(m.K), specific heat (cp) of 2.86 kJ/(kg.K), thermal diffusivity (?) of 4.8·10-5 m²/s, effective diffusivity (Deff) of 9.94·10-10 - 6.29·10-10 m²/s and activation energy (Ea) of 14.90 kJ/mol. These results showed a similarity of values between cupuassu and cocoa and allows to perform more specific studies for the development of dryers for the cupuassu almonds.

Thermal Properties Measurement of Particulate Fouling Samples of Air-Cooled Heat Exchangers Using Laser Flash Method

2020 ◽  
Author(s):  
Arjun Sharma ◽  
M. D. Islam ◽  
Ebrahim Al Hajri
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Middle East ◽  
Specific Heat ◽  
Thermophysical Properties ◽  
Heat Exchangers ◽  
Laser Flash ◽  
Flash Method ◽  
Particulate Fouling ◽  
Major Factors

Abstract Fouling is one of the major factors that drastically affects heat exchanger performance. Especially in Middle East where most of the heat exchangers are air cooled due to scarcity of water. As these heat exchangers are placed in a harsh climate, they are at high risk of low performance due to dusty/sticky particulate fouling. In order to identify possible active/passive methods to control or ideally eliminate particulate fouling, it is desirable to know exact thermophysical properties of such particulate fouling. This study presents thermophysical property characterization of selected fouling samples from eight different fin fan heat exchangers installed in an oil & gas facility in the Middle East. Laser flash Analysis (LFA) method is a well-known technique for measurement of the thermophysical properties: thermal diffusivity, specific heat and thermal conductivity of materials. A new technique was developed to prepare powder particulate fouling samples to make them as disc shaped samples while maintaining the range of ± 12 mm diameter and ± 2 mm thickness. The LFA measurements was conducted using LFA 447 Nano Flash Netzsch over the temperature range from 25 °C to 125°C. The thermal diffusivity was measured with an accuracy of ± 3% and the specific heat capacity with an accuracy of ± 5%. As the thermal conductivity is a product of these two measured values, is calculated with an accuracy of ± 5.8% and the measurement repeatability was within 2%.

Thermophysical Characterization of Genipap Pulp

2010 ◽  
Vol 6 (3) ◽  
Author(s):  
Normane Mirele Chaves da Silva ◽  
Renata Cristina Ferreira Bonomo ◽  
Luciano Brito Rodrigues ◽  
Modesto Antonio Chaves ◽  
Rafael da Costa Ihéu Fontan ◽  
...  
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Water Content ◽  
Thermophysical Properties ◽  
Empirical Models ◽  
Influence Of Temperature ◽  
Thermophysical Characterization

The influence of temperature and water content on thermophysical properties (density, thermal diffusivity, thermal conductivity and specific heat) of genipap (Genipa americana, L) pulp at medium maturity were studied. The thermophysical properties were determined at concentrations between 6.0% m/m and 24.0% m/m of water content and temperatures range of 5 to 80°C. The density decreased with increase in temperature and water content, while the thermal diffusivity and conductivity increased as temperature and water content increased. The specific heat decreased with the moisture content. Empirical models were fitted to the experimental data for each property and the accuracy of those models was checked.

scholarly journals Influence of molten salt-(FLiNaK) thermophysical properties on a heated tube using CFD RANS turbulence modeling of an experimental testbed

2019 ◽  
Vol 5 ◽  
pp. 16
Author(s):  
Ramiro Freile ◽  
Mark Kimber
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Transfer Coefficient ◽  
Transfer Coefficient ◽  
Molten Salt ◽  
Thermophysical Properties ◽  
Material Properties ◽  
Thermal Hydraulics ◽  
Cfd Simulations ◽  
The Heat Transfer Coefficient

In a liquid fuel molten salt reactor (MSR) a key factor to consider upon its design is the strong coupling between different physics present such as neutronics, thermo-mechanics and thermal-hydraulics. Focusing in the thermal-hydraulics aspect, it is required that the heat transfer is well characterized. For this purpose, turbulent models used for FLiNaK flow must be valid, and its thermophysical properties must be accurately described. In the literature, there are several expressions for each material property, with differences that can be significant. The goal of this study is to demonstrate and quantify the impact that the uncertainty in thermophysical properties has on key metrics of thermal hydraulic importance for MSRs, in particular on the heat transfer coefficient. In order to achieve this, computational fluid dynamics (CFD) simulations using the RANS k-ω SST model were compared to published experiment data on molten salt. Various correlations for FLiNaK’s material properties were used. It was observed that the uncertainty in FLiNaK’s thermophysical properties lead to a significant variance in the heat coefficient. Motivated by this, additional CFD simulations were done to obtain sensitivity coefficients for each thermophysical property. With this information, the effect of the variation of each one of the material properties on the heat transfer coefficient was quantified performing a one factor at a time approach (OAT). The results of this sensitivity analysis showed that the most critical thermophysical properties of FLiNaK towards the determination of the heat transfer coefficient are the viscosity and the thermal conductivity. More specifically the dimensionless sensitivity coefficient, which is defined as the percent variation of the heat transfer with respect to the percent variation of the respective property, was −0.51 and 0.67 respectively. According to the different correlations, the maximum percent variations for these properties is 18% and 26% respectively, which yields a variation in the predicted heat transfer coefficient as high as 9% and 17% for the viscosity and thermal conductivity, respectively. It was also demonstrated that the Nusselt number trends found from the simulations were captured much better using the Sieder Tate correlation than the Dittus Boelter correlation. Future work accommodating additional turbulence models and higher fidelity physics will help to determine whether the Sieder Tate expression truly captures the physics of interest or whether the agreement seen in the current work is simply reflective of the single turbulence model employed.

Thermophysical Properties of AS4/3501-6 Carbon-Epoxy Composite

2013 ◽  
Author(s):  
Amber Vital ◽  
Bradley Doleman ◽  
Messiha Saad
Keyword(s):  
Thermal Conductivity ◽  
Composite Materials ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Thermophysical Properties ◽  
Critical Role ◽  
Flash Method ◽  
Energy Storage Devices ◽  
Temperature Levels ◽  
American Society

As today’s technology continues to develop at a rate that was once unimaginable, the demand for new materials that will outperform traditional materials also increases dramatically. To meet these challenges, monolithic materials are being combined to develop new unique materials called composites. Thermophysical properties of composite materials such as thermal conductivity, diffusivity, specific heat, and thermal expansion are very important in engineering design process and analysis of aerospace vehicles as well as space systems. These properties are also important in power generation, transportation, and energy storage devices including fuel cells. Thermal conductivity is the property that determines the working temperature levels of a material and plays a critical role in the performance of materials in high temperature applications. This parameter is important in problems involving heat transfer and thermal structures. The objective of this paper is to develop a thermal properties database for the carbon-epoxy AS4/3501-6 composite. The AS4 carbon fiber used is a unidirectional continuous PAN based fiber, and the 3501-6 epoxy resin is amine cured and provides low shrinkage during the curing process while maintain resistance to chemicals and solvents. The thermophysical properties of the AS4 composite have been investigated using experimental methods. The flash method was used to measure the thermal diffusivity of the composite based on the American Society for Testing and Materials standard, ASTM E1461. In addition, the Differential Scanning Calorimeter was used in accordance with the ASTM E1269 standard to measure the specific heat. The measured thermal diffusivity, specific heat, and density were used to compute the thermal conductivity, thus adding to the currently insufficient database for composite materials and foams.

Thermophysical Properties of Metakaolin Geopolymers Based on Na2SiO3/NaOH Ratio

2018 ◽  
Vol 280 ◽  
pp. 487-493 ◽  
Author(s):  
Ain Jaya Nur ◽  
Yun Ming Liew ◽  
Mohd Mustafa Abdullah Al Bakri ◽  
Cheng Yong Heah
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Sodium Silicate ◽  
Thermophysical Properties ◽  
Insulating Material ◽  
Thermal Insulating ◽  
High Specific Heat ◽  
Alkaline Activator

In the present work, the effect of different sodium silicate-to-sodium hydroxide ratio on the physical, mechanical and thermophysical properties of metakaolin geopolymers (MkGPs) was investigated. Geopolymers were prepared by activating the metakaolin with a mixture of NaOH and sodium silicate (Na2SiO3). The products obtained were characterized after 28 days of ageing. The density, porosity, compressive strength, thermal conductivity (TC), thermal diffusivity and specific heat capacity were determined. In general, the Na2SiO3/NaOH ratio has a significant effect on the compressive strength of the MkGPs. The thermal conductivity, thermal diffusivity and specific heat of MkGps measured in this work were in the range between 0.44 to 0.92 W/mK, 0.22 to 0.44 mm2/s and 1 to 3.7 MJ/m3K respectively. The highest compressive strength was 32 MPa achieved with Na2SiO3/NaOH ratio of 1.0. This mix has the best thermophysical performance due to low thermal conductivity, low thermal diffusivity and high specific heat compared to the other alkaline activator ratios. The results showed that the geopolymer is able to be used as the thermal insulating material.

scholarly journals Effect of Rubber Aggregates on the Thermophysical Properties of Self-Consolidating Concrete

2014 ◽  
Vol 08 (1) ◽  
Keyword(s):  
Thermal Conductivity ◽  
Experimental Study ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Thermal Performance ◽  
Thermophysical Properties ◽  
Self Consolidating Concrete ◽  
Rubber Aggregates

n this work, our choice fell on the exploitation of rubber aggregates from used tires. In this context, an experimental study was conducted to provide more data on the effect of rubber aggregates on the thermophysical properties of self- consolidating concrete (SCC). To this end , four sets of rectangular specimens were prepared by varying the proportion of the rubber aggregates with percentages of 0 %, 10 %, 20 % and 30 % of the volume of gravel .Tests on hardened self-consolidating concrete rubber SCCR included measuring the thermal conductivity and the thermal diffusivity by the method of the boxes at steady and determining the specific heat . The results showed that the thermal conductivity and thermal diffusivity were decreased according to the increase of the percentage of rubber aggregates. This decrease was significantly improved thermal performance of the SCCR.

scholarly journals Effect of Frying Temperature and Time on Thermophysical Properties and Quality Attributes of Deep-Fat Fried Plantain (Dodo)

2021 ◽  
pp. 1-6
Author(s):  
J. A. Adeyanju ◽  
B. E. Alabi ◽  
A. O. Abioye ◽  
A. A. Adekunle ◽  
A. A. Oloyede
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Moisture Content ◽  
Specific Heat ◽  
Product Quality ◽  
Thermophysical Properties ◽  
Quality Attributes ◽  
Processing Conditions ◽  
Frying Temperature ◽  
Acceptable Quality

This study investigated the effect of the processing conditions (frying temperature and time) on the thermophysical properties and product quality attributes of deep-fat fried plantain (dodo). The plantain were deep-fried at various frying temperatures (150-190 °C) and time intervals (120-240 sec). The thermophysical properties determined include specific heat, thermal conductivity, thermal diffusivity and density. The product quality attributes were moisture content, oil content and colour. The specific heat, thermal conductivity, thermal diffusivity and density of the deep-fat fried plantain ranged from 2.68 to 2.33 kJ/kgK, 0.37 to 0.33 W/mK, 1.12 to 1.36 x10-7 m2/s and 1049.50 to 1257.00 kg/m3, respectively. The quality attributes of dodo varied from 0.24 to 0.65 abs, 30.37 to 43.40% and 9.96 to 14.25% for colour, It was observed that the specific heat, thermal conductivity, thermal diffusivity and moisture content of the deep-fat fried plantain were significantly reduced as frying temperature and time increased. The colour and fat content of dodo were found to increase with increased temperature and time of frying. Outcome of the study resulted in the development of dodo with high acceptable quality characteristics. Therefore, generated data will be useful in choice of processing conditions for plantain and development of fryer.

Effect of Mechanical Compression on Thermal Characteristics of Tissue-Mimicking Material

2015 ◽  
Author(s):  
Binh T. Hoang ◽  
Austin Roth ◽  
Adriana Druma ◽  
Mallika Keralapura ◽  
Sang-Joon John Lee
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Flux ◽  
Heat Capacity ◽  
Thermal Diffusivity ◽  
Specific Heat ◽  
Specific Heat Capacity ◽  
Room Temperature ◽  
Mechanical Compression ◽  
Tissue Mimicking Material

Tissue-mimicking materials (TMM) are often used as surrogates for human tissue when developing prospective treatments such as thermal ablation of tumors. Localized heating or ablation may be applied by methods including high-intensity focused ultrasound (HIFU), radio frequency (RF), microwave, and laser treatment. In such methods, confining the heated region to a narrow target is an important concern for minimizing collateral damage to surrounding healthy tissue. Mechanical compression can potentially assist in confining heat near a target region by constricting microvascular blood flow. However, characterization of the effects of compression on thermal properties of the tissue itself (apart from microvasculature) is needed for accurate modeling of heat transfer. Accordingly this study presents a method and material characterization results that quantify the extent to which mechanical compression alters thermal conductivity, specific heat capacity, and thermal diffusivity of a polyacrylamide-based TMM. Cylindrical test specimens were cast from polyacrylamide material with diameter of 50 mm and height of 45 mm. Compression was applied using custom apparatus for applying prescribed uniaxial displacement, with a modular configuration for testing under ambient temperature as well as on a hot plate. Compression force at room temperature was measured with a load cell that was positioned in-line between compression plates. Prescribed heat flux was delivered based on power input, as quantified with the use of a reference sample in a thermal resistance network. Temperature was measured by an array of thermocouples. Software simulations were performed using finite element analysis (FEA) for structural deformation and computational fluid dynamics (CFD) for heat transfer under the combined effects of conduction and convection. The simulations provided estimates of deformed shape and thermal losses that were compared to experimental measurements. Mechanical stress-strain tests using three TMM replicate specimens at room temperature showed a linear stress-strain relationship from approximately 2% to 14% strain and a compressive modulus of elasticity ranging from 7.56 kPa to 12.7 kPa. Distributed temperature measurements under an imposed heat flux resulted in thermal conductivity between 0.89 W/(m·K) and 1.04 W/(m·K), specific heat capacity between 5590 J/(kg·K) and 6720 J/(kg·K) and thermal diffusivity between 1.29 × 10−7 m 2 /s to 1.71 × 10−7 m2/ s. Viscoelastic effects were observed to reach steady state after approximately 20 seconds, with full elastic recovery upon unloading. Thermal conductivity and thermal diffusivity were observed to decrease under mechanical compression, while specific heat capacity was observed to increase. The results affirm that thermal properties of tissue-mimicking material can be altered by mechanical compression. These findings can be applied to future investigation of temperature distribution during localized ablation by methods such as HIFU, and can be extended to refined material modeling of perfused tissue under compression.

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