scholarly journals Measurement of the in-plane thermal conductivity by steady-state infrared thermography

2017 ◽  
Vol 88 (4) ◽  
pp. 044903 ◽  
Author(s):  
Anton Greppmair ◽  
Benedikt Stoib ◽  
Nitin Saxena ◽  
Caroline Gerstberger ◽  
Peter Müller-Buschbaum ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Infrared Thermography

scholarly journals Thermal conductivity of insulating refractory materials: comparison of steady-state and transient measurement methods

Open Ceramics ◽  
2021 ◽  
pp. 100118
Author(s):  
Diana Vitiello ◽  
Benoit Nait-Ali ◽  
Nicolas Tessier-Doyen ◽  
Thorsten Tonnesen ◽  
Luís Laím ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Measurement Methods ◽  
Refractory Materials ◽  
Transient Measurement

Design of a Steady-State, Parallel-Plate Thermal Conductivity Apparatus for Nanofluids and Comparative Measurements With Transient HWTC Apparatus

2010 ◽  
Author(s):  
Milivoje M. Kostic ◽  
Casey J. Walleck
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Parallel Plate ◽  
Measurement Method ◽  
Mixture Theory ◽  
Hot Wire ◽  
Electro Magnetic ◽  
Magnetic Phenomena ◽  
Thermal Conductivities

A steady-state, parallel-plate thermal conductivity (PPTC) apparatus has been developed and used for comparative measurements of complex POLY-nanofluids, in order to compare results with the corresponding measurements using the transient, hotwire thermal conductivity (HWTC) apparatus. The related measurements in the literature, mostly with HWTC method, have been inconsistent and with measured thermal conductivities far beyond prediction using the well-known mixture theory. The objective was to check out if existing and well-established HWTC method might have some unknown issues while measuring TC of complex nano-mixture suspensions, like electro-magnetic phenomena, undetectable hot-wire vibrations, and others. These initial and limited measurements have shown considerable difference between the two methods, where the TC enhancements measured with PPTC apparatus were about three times smaller than with HWTC apparatus, the former data being much closer to the mixture theory prediction. However, the influence of measurement method is not conclusive since it has been observed that the complex nano-mixture suspensions were very unstable during the lengthy steady-state measurements as compared to rather quick transient HWTC method. The nanofluid suspension instability might be the main reason for very inconsistent results in the literature. It is necessary to expend investigation with more stable nano-mixture suspensions.

scholarly journals Improving the quality of alumina-containing sinter using water-cooled furnace shell

2012 ◽  
Vol 44 (3) ◽  
pp. 281-286
Author(s):  
A.V. Aleksandrov ◽  
V.V. Aleksandrov
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Heat Exchange ◽  
Energy Balance ◽  
Cold Water ◽  
Sintering Temperature ◽  
Radiant Heat ◽  
Thermal Processes ◽  
Technical Solutions

This article deals with the use of computer modeling to develop technical solutions to ensure better quality of alumina-containing sinter. The simulation accounted for the influence of the feed materials on the thermal processes in the furnace. The energy balance (including thermal conductivity, heat convection and radiant heat exchange) was solved assuming steady state. A good correlation was observed for the actual and calculated temperatures of the solids and gases, with less than 15% discrepancy. Using the model of the furnace investigated the possibility of lowering the temperature of sintering by removing heat from the outside of the furnace shell. To reduce the sintering temperature to 1000 ?C length of the refractory lined steel is 5 m, the height of the lining should not exceed - 0.06 m, the required rate of cold water - 54.7 m3/h

scholarly journals The Influence of Burial Depth and Soil Thermal Conductivity on Heat Transfer in Buried CO2 Pipelines for CCS: A Parametric Study

2020 ◽  
Author(s):  
Babafemi Olugunwa ◽  
Julia Race ◽  
Tahsin Tezdogan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Steady State ◽  
Thermal Resistance ◽  
Parametric Study ◽  
Flow Assurance ◽  
Burial Depth ◽  
Soil Thermal Conductivity ◽  
Dense Phase ◽  
Pipeline Transportation

Abstract Pipeline heat transfer modelling of buried pipelines is integral to the design and operation of onshore pipelines to aid the reduction of flow assurance challenges such as carbon dioxide (CO2) gas hydrate formation during pipeline transportation of dense phase CO2 in carbon capture and storage (CCS) applications. In CO2 pipelines for CCS, there are still challenges and gaps in knowledge in the pipeline transportation of supercritical CO2 due to its unique thermophysical properties as a single, dense phase liquid above its critical point. Although the design and operation of pipelines for bulk fluid transport is well established, the design stage is incomplete without the heat transfer calculations as part of the steady state hydraulic and flow assurance design stages. This paper investigates the steady state heat transfer in a buried onshore dense phase CO2 pipelines analytically using the conduction shape factor and thermal resistance method to evaluate for the heat loss from an uninsulated pipeline. A parametric study that critically analyses the effect of variation in pipeline burial depth and soil thermal conductivity on the heat transfer rate, soil thermal resistance and the overall heat transfer coefficient (OHTC) is investigated. This is done using a one-dimensional heat conduction model at constant temperature of the dense phase CO2 fluid. The results presented show that the influence of soil thermal conductivity and pipeline burial depth on the rate of heat transfer, soil thermal resistance and OHTC is dependent on the average constant ambient temperature in buried dense phase CO2 onshore pipelines. Modelling results show that there are significant effects of the ambient natural convection on the soil temperature distribution which creates a thermal influence region in the soil along the pipeline that cannot be ignored in the steady state modelling and as such should be modelled as a conjugate heat transfer problem during pipeline design.

Determination of Thermal Conductivity of Soils: A Need for Computing Heat Loss Through Buried Submarine Pipelines

1982 ◽  
Vol 22 (04) ◽  
pp. 558-562 ◽  
Author(s):  
P.C. Rawat ◽  
S.L. Agarwal
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Crude Oil ◽  
Rheological Properties ◽  
Heat Loss ◽  
Experimental Results ◽  
Dry Density ◽  
Empirical Relationships ◽  
Thermal Conductivities

Abstract An important parameter required for computing heat loss through buried submarine pipelines transporting crude oil is the thermal conductivity of soils. This paper describes an apparatus designed for determination of the thermal conductivity of soils at the desired moisture/ density condition in the laboratory under steady-state conditions. Experimental results on the three soils studied show that thermal conductivity increases as dry density increases at a constant moisture content and that it increases as water content increases at constant dry density. These results confirm the trends isolated earlier by Kersten. The experimental results are compared with the available empirical relationships. Kersten's relation is observed to predict the thermal conductivity of these soils reasonably. The predictions from Makowski and Mochlinski's relation (quoted by Szilas) are not good but improve if the sum of silt and clay fractions is treated as a clay fraction in the computation. Introduction Submarine pipelines are used extensively for transporting crude oil from offshore to other pipelines offshore or onshore. These pipelines usually are steel pipes covered with a coating of concrete. They often are buried some depth below the mudline. The rheological properties of different crude oils vary, and their viscosities increase with a decrease in temperature. Below some temperature, the liquid oil tends to gel. Therefore, for efficient transportation, the crude must be at a relatively high temperature so that it has a low viscosity. The temperature of the soil/water system surrounding a submarine pipeline is usually lower than that of oil. This temperature difference induces heat to flow from the oil to the environment, and the temperature of the oil decreases as it travels along the length of the pipeline. One must ensure that this temperature reduction does not exceed desirable limits dictated by the rheological properties of oil and by the imperatives of efficient economic properties of oil and by the imperatives of efficient economic transportation. Thus the analytical problem is to predict the temperature of crude in the pipeline some distance away from the input station. To do so, knowledge of the overall heat transfer coefficient for the pipeline is required, for which, in turn, it is necessary to know the thermal conductivities of the oil, the pipeline materials and its coating, and the soil. This paper presents thermal conductivities of soils determined in the laboratory under steady-state conditions and also presents a comparison of the test results of three soils with values determined from existing empirical relationships. Literature Review Heat moves spontaneously from higher to lower temperatures. In a completely dry porous body, transmission of heat can take place not only by conduction through the solid framework of the body and the air in the pores but also by convection and radiation between the walls of a pore and by macro- and microdistillation. In soils, however, it can be ascribed essentially to conduction, a molecular phenomenon that can be expressed in terms of experimentally determined coefficients of conductivity or resistivity, although these actually may include microdistillation and other mechanisms. SPEJ p. 558

Steady-State Investigation of Vapor Deposited Micro Heat Pipe Arrays

1995 ◽  
Vol 117 (1) ◽  
pp. 75-81 ◽  
Author(s):  
A. K. Mallik ◽  
G. P. Peterson
Keyword(s):  
Thermal Conductivity ◽  
Steady State ◽  
Surface Temperature ◽  
Heat Pipe ◽  
Effective Thermal Conductivity ◽  
Heat Pipes ◽  
Temperature Gradients ◽  
Bottom Surface ◽  
Micro Heat Pipe ◽  
Micro Heat Pipes

An experimental investigation of vapor deposited micro heat pipe arrays was conducted using arrays of 34 and 66 micro heat pipes occupying 0.75 and 1.45 percent of the cross-sectional area, respectively. The performance of wafers containing the arrays was compared with that of a plain silicon wafer. All of the wafers had 8 × 8 mm thermofoil heaters located on the bottom surface to simulate the active devices in an actual application. The temperature distributions across the wafers were obtained using a Hughes Probeye TVS Infrared Thermal Imaging System and a standard VHS video recorder. For wafers containing arrays of 34 vapor deposited micro heat pipes, the steady-state experimental data indicated a reduction in the maximum surface temperature and temperature gradients of 24.4 and 27.4 percent, respectively, coupled with an improvement in the effective thermal conductivity of 41.7 percent. For wafers containing arrays of 66 vapor deposited micro heat pipes, the corresponding reductions in the surface temperature and temperature gradients were 29.0 and 41.7 percent, respectively, and the effective thermal conductivity increased 47.1 percent, for input heat fluxes of 4.70 W/cm2. The experimental results were compared with the results of a previously developed numerical model, which was shown to predict the temperature distribution with a high degree of accuracy, for wafers both with and without the heat pipe arrays.

Sign in / Sign up

Export Citation Format

Share Document