A Method of Measuring the Properties of Ash Deposits in a Coal Fired Reactor

2007 ◽  
Author(s):  
Travis J. Moore ◽  
Matthew R. Jones
Keyword(s):  
Thermal Conductivity ◽  
Power Generation ◽  
Coal Combustion ◽  
Measurement Errors ◽  
Combustion Process ◽  
Combustion Chambers ◽  
The Earth ◽  
Almost All ◽  
Total Emittance

Coal is an important source of energy because of its potential for power generation and its abundance in the earth. A great deal of research is dedicated to developing cleaner and more efficient methods of generating power from coal. A major problem associated with almost all power generation processes involving coal is the formation of ash. Some of the ash that is formed is deposited on the tubes and walls of the combustion chambers. This accumulation of ash can significantly affect the thermal transport in the boiler. Modeling of the heat transfer occurring in a coal combustion process requires knowledge of the properties of these deposits. Accurate measurements of these properties will lead to better modeling capabilities and improved optimization of the design of coal fired reactors. Therefore, a method for accurate, in situ measurement of the emittance and thermal conductivity is highly desirable. This paper describes the development of a method for determining the total emittance and thermal conductivity of the deposited ash layers and analyzes the sensitivity of these properties to measurement errors.

scholarly journals Measuring thermal conductivity of frozen soil using fiber optic sensors

2021 ◽  
Vol 135 (2) ◽  
pp. 82-93
Author(s):  
Bing Wu ◽  
◽  
Hong-Hu Zhu ◽  
Dingfeng Cao ◽  
◽  
...  
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Measurement Errors ◽  
Measurement Accuracy ◽  
Fiber Optic ◽  
Frozen Soil ◽  
In Situ Monitoring ◽  
Geotechnical Parameters ◽  
Lower Limits

The thermal conductivity is crucial for determining heat transfer in frozen soil. However, it is a challenge to obtain accurate measurement values due to the instability of soil properties. Recently, the fiber optic sensing technologies has enabled accurate and distributed in-situ monitoring of a variety of geotechnical parameters. This paper aims to explore the feasibility of actively heated fiber Bragg grating (AH-FBG) method in measuring thermal conductivity of frozen soil. A series of laboratory experiments were performed on frozen soil samples at different initial temperatures from −16 to 5 ℃. The theoretical upper and lower limits of thermal conductivity were used to evaluate the AHFBG measurements. The thermal conductivity recorded by a heat transfer analyzer was used to identify the measurement accuracy. The experimental results that the AH-FBG method can accurately measure the thermal conductivity of frozen soil when the initial temperature is below −6 ℃, and the measurement error is within acceptable range of 0.8%. When the soil temperature is between −6 and 0 ℃, significant measurement errors were observed due to the disturbance of heating to the frozen soil.

Rendez vous with Saturn's rings

1984 ◽  
Vol 75 ◽  
pp. 743-759 ◽  
Author(s):  
Kerry T. Nock
Keyword(s):  
Solar Energy ◽  
Electric Propulsion ◽  
Power Source ◽  
Propulsion System ◽  
Low Thrust ◽  
Ring Plane ◽  
The Earth ◽  
Total Impulse ◽  
Saturn's Rings

ABSTRACTA mission to rendezvous with the rings of Saturn is studied with regard to science rationale and instrumentation and engineering feasibility and design. Future detailedin situexploration of the rings of Saturn will require spacecraft systems with enormous propulsive capability. NASA is currently studying the critical technologies for just such a system, called Nuclear Electric Propulsion (NEP). Electric propulsion is the only technology which can effectively provide the required total impulse for this demanding mission. Furthermore, the power source must be nuclear because the solar energy reaching Saturn is only 1% of that at the Earth. An important aspect of this mission is the ability of the low thrust propulsion system to continuously boost the spacecraft above the ring plane as it spirals in toward Saturn, thus enabling scientific measurements of ring particles from only a few kilometers.

scholarly journals Method for determining the thermal conductivity of in situ formation rock using drilling cuttings

AIP Advances ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 065015
Author(s):  
Fu Yi ◽  
Xupeng Qi ◽  
Xuexin Zheng ◽  
Huize Yu ◽  
Wenming Bai ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
In Situ Formation

Synergistic effect of phase structures and in situ sintering of silver fillers on thermal conductivity of epoxy/polyethersulphone/silver filler composites

Polymer ◽  
2021 ◽  
pp. 123726
Author(s):  
Hajime Kishi ◽  
Takashi Saruwatari ◽  
Takemasa Mototsuka ◽  
Sanae Tanaka ◽  
Takeshi Kakibe ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Synergistic Effect ◽  
Phase Structures

scholarly journals Diversity of Biodeteriorative Bacterial and Fungal Consortia in Winter and Summer on Historical Sandstone of the Northern Pergola, Museum of King John III’s Palace at Wilanow, Poland

2021 ◽  
Vol 11 (2) ◽  
pp. 620
Author(s):  
Magdalena Dyda ◽  
Agnieszka Laudy ◽  
Przemyslaw Decewicz ◽  
Krzysztof Romaniuk ◽  
Martyna Ciezkowska ◽  
...  
Keyword(s):  
Seasonal Changes ◽  
Microbial Community Composition ◽  
Fungal Communities ◽  
Bacterial Strains ◽  
Microbial Biodiversity ◽  
Acidophilic Bacteria ◽  
Almost All ◽  
Generation Sequencing ◽  
King John

The aim of the presented investigation was to describe seasonal changes of microbial community composition in situ in different biocenoses on historical sandstone of the Northern Pergola in the Museum of King John III’s Palace at Wilanow (Poland). The microbial biodiversity was analyzed by the application of Illumina-based next-generation sequencing methods. The metabarcoding analysis allowed for detecting lichenized fungi taxa with the clear domination of two genera: Lecania and Rhinocladiella. It was also observed that, during winter, the richness of fungal communities increased in the biocenoses dominated by lichens and mosses. The metabarcoding analysis showed 34 bacterial genera, with a clear domination of Sphingomonas spp. across almost all biocenoses. Acidophilic bacteria from Acidobacteriaceae and Acetobacteraceae families were also identified, and the results showed that a significant number of bacterial strains isolated during the summer displayed the ability to acidification in contrast to strains isolated in winter, when a large number of isolates displayed alkalizing activity. Other bacteria capable of nitrogen fixation and hydrocarbon utilization (including aromatic hydrocarbons) as well as halophilic microorganisms were also found. The diversity of organisms in the biofilm ensures its stability throughout the year despite the differences recorded between winter and summer.

In-situ reaction between arsenic/selenium and minerals in fly ash at high temperature during blended coal combustion

2020 ◽  
Vol 48 (11) ◽  
pp. 1356-1364
Author(s):  
Jun HAN ◽  
Yang-shuo LIANG ◽  
Bo ZHAO ◽  
Zi-jiang XIONG ◽  
Lin-bo QIN ◽  
...  
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
Coal Combustion ◽  
In Situ Reaction ◽  
Blended Coal

Errors of In Situ Illuminance Measurements

2016 ◽  
Vol 824 ◽  
pp. 676-683
Author(s):  
Michaela Hlásková ◽  
Lenka Gábrová ◽  
František Vajkay
Keyword(s):  
Measurement Errors ◽  
Daily Basis ◽  
Lighting Design ◽  
Public Health Authority ◽  
Construction Work ◽  
Measurement Instruments ◽  
Artificial Lighting ◽  
Lighting Conditions ◽  
Overcast Sky

Lighting conditions in buildings are verified by experts on a daily basis. Such verifications may be done at several phases in various ways. In the field of daylighting, it is common to make an assessment within the pre-design and in-design phases of a construction work throughout calculations, only rarely by measurements. This approach is the opposite of artificial lighting design, which is done within the in-design phase by calculations and is verified by measurements in post-realization phase. The verification of artificial lighting design is required by the building and public health authority otherwise buildings cannot be approved to use. In the field of daylighting, measurements could be performed as well, nevertheless those are often problematic because regulations usually require fulfilments of the daylight factor which can be determined only under CIE overcast sky. Howbeit, both artificial lighting and daylighting measurements are influenced by many errors, e.g. errors of light measurement instruments, measurement conditions, measurement methods and human factor. The paper is focused on this aspect of lighting design, more specifically on the daylighting measurement errors.

Complete Characterization of Thermoelectric Materials by a Combined van der Pauw Approach and the Effect of Radiation Losses

2011 ◽  
Vol 1314 ◽  
Author(s):  
Johannes de Boor ◽  
Volker Schmidt
Keyword(s):  
Thermal Conductivity ◽  
Measurement Errors ◽  
Conductivity Measurement ◽  
Short Review ◽  
Complete Characterization ◽  
Radiative Heat Loss ◽  
Radiation Losses ◽  
Novel Method ◽  
Simple Estimation ◽  
Van Der Pauw

AbstractWe have recently presented a novel method for a complete thermoelectric characterization [J. de Boor, V. Schmidt. Adv. Mater. 22:4303, (2010)]. This method is based on the well-known electrical van der Pauw method and allows measurement of the electrical and thermal conductivity, the Seebeck coefficient and the thermoelectric figure of merit. After a short review of this method we will discuss the systematic measurement errors of the method. It turns out that radiative heat loss can affect the thermal conductivity measurement significantly. We will give a simple estimation for the relative error due to radiation losses and discuss error minimizing strategies.

scholarly journals Improvement of mechanical properties of HfB2-based composites by incorporating in situ SiC reinforcement through pressureless sintering

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Ghadami ◽  
E. Taheri-Nassaj ◽  
H. R. Baharvandi ◽  
F. Ghadami
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Relative Density ◽  
Pressureless Sintering ◽  
Sintering Process ◽  
Vacuum Atmosphere ◽  
Sic Reinforcement ◽  
Microstructural Studies ◽  
Composite Samples

AbstractHfB2, Si, and activated carbon powders were selected to fabricate 0–30 vol% SiC reinforced HfB2-based composite. Pressureless sintering process was performed at 2050 °C for 4 h under a vacuum atmosphere. Microstructural studies revealed that in situ SiC reinforcement was formed and distributed in the composite according to the following reaction: Si + C = SiC. A maximum relative density of 98% was measured for the 20 vol% SiC containing HfB2 composite. Mechanical investigations showed that the hardness and the fracture toughness of these composites were increased and reached up to 21.2 GPa for HfB2-30 vol% SiC and 4.9 MPa.m1/2 for HfB2-20 vol% SiC, respectively. Results showed that alpha-SiC reinforcements were created jagged, irregular, and elongated in shape which were in situ formed between HfB2 grains and filled the porosities. Formation of alpha-SiC contributed to improving the relative density and mechanical properties of the composite samples. By increasing SiC content, an enhanced trend of thermal conductivity was observed as well as a reduced trend for electrical conductivity.

In-situ synthesized nanocrystalline UO2/SiC composite with superior thermal conductivity

2021 ◽  
Author(s):  
Dezhi Zhang ◽  
Yingru Li ◽  
Zhenliang Yang ◽  
Bingqing Li ◽  
Zhiyi Wang ◽  
...  
Keyword(s):  
Thermal Conductivity
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