Ratio of Radial to Total Heat Flow in Circular Rod

1963 ◽  
Vol 85 (3) ◽  
pp. 285-286 ◽  
Author(s):  
Y. T. Tsui ◽  
F. K. Tsou
Keyword(s):  
Heat Flow ◽  
Total Heat ◽  
Total Heat Flow

Simulation and Diagnostics of the External and Internal Circulation Flows of Solids in a Biomass Fired CFB Boiler

2004 ◽  
Author(s):  
Daniel Ha¨ggsta˚hl ◽  
Catrin Bartusch ◽  
Erik Dahlquist ◽  
Shilie Weng
Keyword(s):  
Heat Flow ◽  
Circulating Fluidized Bed ◽  
Internal Heat ◽  
Circulation Model ◽  
Internal Flow ◽  
Total Heat ◽  
Heat Output ◽  
Circulation Flow ◽  
Total Heat Flow ◽  
Cfb Boiler

Ash related operational problems are very common in biomass fired boilers. Biomass naturally contains both sodium chloride and potassium chloride and theses compounds lower the melting temperature of the ash which may cause large operational problems with agglomeration and defluidization in Circulating Fluidized Bed (CFB) boilers. The number of biomass fired CFB-boilers for combined heat and power (CHP) production in the Scandinavian market is growing due to their good combustion efficiency, fuel flexibility and low emissions. The power companies are asking for a method to calculate the internal and external circulation flows of solids in the boiler and an accurate diagnostic method to detect initial agglomeration in order to be able to prevent the problem of defluidization that leads to large costs and loss of revenue when the boiler has to be shut down for cleaning. Two heat and mass balance based models have been developed in order to calculate the fuel flow and the internal and external solids circulation flows in a CFB boiler with internal heat exchangers (INTREX). The solids circulation model is divided into three parts: cyclone, combustion and INTREX chambers. Measurements used in the calculation are from commissioning tests on CFB-boiler 5 at Ma¨larEnergi in Va¨stera˚s, Sweden. The boiler was manufactured by Foster Wheeler OY in Finland and has a thermal heat output of 157 MW. The external solids flow at 100% load, with and without air humidification, is 215 kg/s and the internal solids circulation is 93 kg/s. The external solids circulation flow at 60% load is 30 kg/s and the internal solids circulation flow is 486 kg/s. At 60% load, there is no data available for validation, which means that this is more an estimate then a calculation. The calculated internal flow of solids is very sensitive to changes in the total heat flow in the INTREX chamber caused by agglomeration or combustion, whereas the external solids flow is not affected. Hence initial agglomeration and combustion can be detected. A simulated agglomeration in the INTREX chambers by decreasing the total heat flow by 1%, led to a decrease in the internal solids circulation flow by 11%. A simulation of combustion in the INTREX chamber of 0.5 kg/s of fuel entering the chamber corresponds to an increase in the total heat flow of 22% and a decrease in the calculated internal mass flow of 16%. The potential for using this method of diagnostics for detecting initial agglomeration is very promising.

EFFICIENCY OF SOLAR PROTECTION OF THE MOBILE AGRICULTURAL MACHINE CAB

2020 ◽  
Author(s):  
V.V. Maslensky ◽  
◽  
Y.I. Bulygin
Keyword(s):  
Heat Flow ◽  
Solar Radiation ◽  
Sun Protection ◽  
Total Heat ◽  
Total Heat Flow ◽  
Agricultural Machine ◽  
Heat Protection ◽  
Low Efficiency ◽  
Working Day

The article checks the effectiveness of translucent enclosing structures of the tractor cab in reducing solar radiation. For this purpose, the value of the total heat flow entering the interior during the entire working day was determined, which was later compared with the hygienic standards. The result demonstrated an average low efficiency of the tractor cab sun protection. In this regard, the use of more effective shading elements and the use of glass with increased light and heat protection properties in light openings is proposed.

Isothermal micro-calorimetry: a tool to predict seed longevity?

2006 ◽  
Vol 16 (2) ◽  
pp. 89-96 ◽  
Author(s):  
Fiona R. Hay ◽  
Michael A.A. O'Neill ◽  
Anthony E. Beezer ◽  
Simon Gaisford
Keyword(s):  
Heat Flow ◽  
Water Content ◽  
High Water ◽  
Seed Longevity ◽  
Total Heat ◽  
Short Term ◽  
Seed Ageing ◽  
Rate Kinetics ◽  
Residual Power ◽  
Water Contents

This paper describes the exploratory use of isothermal micro-calorimetry (IMC) to measure directly the heat flow produced as seeds age. Heat flow was recorded in primed and non-primed (control) seeds of Ranunculus sceleratus L., aged in a micro-calorimeter at 35°C at three different seed water contents [c. 0.12, 0.075 and 0.045 g H2O (g dw)−1]. The rate of heat flow and total heat generated (an indicator of extent of reaction) were generally greater in control seeds, which aged at a faster rate, than in primed seeds. Total heat generated over a given period also increased with increasing water content. The power–time curves did not indicate first- or second-order rate kinetics, consistent with the probability that seed ageing is complex and involves a number of reactions. Even after the capacity to germinate had ceased, there was a residual power signal. As a method, IMC gave consistent results using independent samples at different times. Therefore, short-term experiments at relatively high water contents and/or temperatures may have the potential to predict the relative longevity of seed-lots, at least within a species.

scholarly journals Estimation of microbiological contamination of maize seeds using isothermal calorimetry

2020 ◽  
Vol 142 (2) ◽  
pp. 749-754
Author(s):  
Andrzej Skoczowski ◽  
Sebastian W. Przemieniecki ◽  
Jakub Oliwa ◽  
Monika Kula-Maximenko ◽  
Magdalena Rys ◽  
...  
Keyword(s):  
Heat Flow ◽  
Isothermal Calorimetry ◽  
Heat Emission ◽  
Total Heat ◽  
Raw Material ◽  
Microbiological Contamination ◽  
Maize Seeds ◽  
Number Of Microorganisms ◽  
Bacteria And Fungi ◽  
Isothermal Calorimeter

Abstract The storage of maize seed intended for industrial purposes in foil silo bags is associated with microbiological contamination of the material by bacteria and fungi. This results in the loss of a part of the raw material or its deterioration and causes financial losses. In this paper, the relationship between the number of microorganisms colonizing maize seeds as well as changes in heat flow has been proved. For this purpose, the heat flow and total metabolic heat emission values (total heat) were analyzed. Calorimetric measurements of seed samples were made using the TAM III isothermal calorimeter. The seed samples with the same heat flow curves shape were homogenized, and microbial DNA was isolated from them. The quantitative real-time polymerase chain reaction (qPCR) was performed for detecting the main group of microorganisms colonizing maize seeds. It has been shown that in the case of seeds less affected by Bacillus and fungi (including yeast), the heat flow (in the range of 0–360 min) has a falling shape, while for more infected it grows almost linearly. The more infected maize seeds also show significantly higher values of total heat emission. The described research can be used to quickly assess the degree of seed contamination.

scholarly journals Efecto de la Corriente y Longitud de Arco en Soldaduras con Arco Eléctrico Asistido por Modelado Matemático

2018 ◽  
Vol 3 (1) ◽  
pp. 373
Author(s):  
J. A. Delgado ◽  
M. A. Ramírez Argáez ◽  
P. F. Mendez
Keyword(s):  
Heat Flow ◽  
Arc Welding ◽  
Electrical Potential ◽  
Welding Process ◽  
Maximum Velocity ◽  
Heat Transfer Fluid ◽  
Maximum Temperature ◽  
Arc Length ◽  
Total Heat Flow ◽  
Process Gas

A 2D mathematical model was developed for the GTAW arc welding process (Gas Tungsten Arc Welding). Computational simulations were performed by using the commercial software PHOENICS based on mass and momentum conservation equations as well as on Maxwell equations. The model predicts the electric characteristics of the arc column, flow patterns, temperature profiles, heat flux, total heat flow and the electrical potential, by varying the arc length and the applied current. By increasing the current the arc jet is stronger, hotter and provides more heat to the weld pool, while by increasing the arc length the maximum temperature, maximum velocity and heat flow are unchanged, although a short arc focuses the heat in a small area and a long arc spreads the heat in a wider area of the work piece.Keywords: Electric arc, heat transfer, fluid flow, mathematical modeling. 

Sign in / Sign up

Export Citation Format

Share Document