scholarly journals Calculations of Heat Transfer in Torch Furnaces by Gas Volume Radiation Laws

2016 ◽  
Vol 04 (03) ◽  
pp. 488-503 ◽  
Author(s):  
A. N. Makarov
Keyword(s):  
Heat Transfer ◽  
Gas Volume ◽  
Radiation Laws

A Method for Combustion Calculation Based on Proximate Analysis and Net Calorific Value of Coal

2015 ◽  
Vol 1092-1093 ◽  
pp. 479-482
Author(s):  
Bao Kui Chen ◽  
Feng Zhong Sun
Keyword(s):  
Heat Transfer ◽  
Oxygen Consumption ◽  
Relative Error ◽  
Flue Gas ◽  
Calorific Value ◽  
Proximate Analysis ◽  
Combustible Material ◽  
Testing And Debugging ◽  
Boiler Operation ◽  
Gas Volume

For the combustion calculation of coal fired boiler, a new concept of oxygen consumption for combustible material was proposed which was different from the traditional oxygen consumption for elements. A mathematical model was developed for the combustion calculation. The calculation formulas of theoretical air and flue gas volume were established through reasonable hypothesis and simplification, which were based on proximate analysis and net calorific value of coal. In contrast to the results of the elemental analysis for the 15 different kinds of coals which are typical in China, the average relative error of formulas is lower than 2%, the biggest relative error is 7.11%, which can be used for the control over boiler operation, testing and debugging, and calculation of heat transfer.

Numerical Simulation of Taylor Flow in Micro Circular Tubes

2015 ◽  
Author(s):  
Jingzhi Zhang ◽  
Wei Li
Keyword(s):  
Heat Transfer ◽  
Liquid Film ◽  
Single Phase ◽  
Volume Fraction ◽  
Flow Characteristics ◽  
Constant Heat Flux ◽  
Bulk Temperature ◽  
Capillary Tubes ◽  
Taylor Flow ◽  
Gas Volume

Heat transfer and flow characteristics of Taylor flow in micro capillary tubes have been investigated numerically with the Volume of Fluid (VOF) method. A constant heat flux (32kwm−2) is adopted at the tube wall. All seven computational cases have the same Reynolds number (Re=280), Capillary number (Ca=0.006) and homogenous void fraction (β=0.51), while the inlet gas volume fraction varies from 0.2 to 0.8. The results indicate that liquid slug length (Ll), gas slug length (Lg) and cell length (Lc) vary with α, while liquid film thickness δ remains constant. The friction factor f of Taylor flow is higher than single phase flow. The simulation results agree well with the correlation proposed by Kreutzer et al.. The Local Nusselt number (Nux) gets its peak value at the liquid film region, where the temperature difference between wall temperature (Tw) and fluid bulk temperature (Tbx) is smallest. The average Nu (Nuav) is about 2.8 times of single phase. This means that Taylor bubble can enhance the heat transfer coefficient in micro capillary tubes.

Insights on Heat Transfer at the Top of Steam Chambers in SAGD

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Helen Pinto ◽  
Xin Wang ◽  
Ian D. Gates
Keyword(s):  
Heat Transfer ◽  
Heat Flux ◽  
Oil Sands ◽  
Error Function ◽  
Material Balance ◽  
Heat Transfer Analysis ◽  
Steam Chamber ◽  
Steam Assisted Gravity Drainage ◽  
Critical Issues ◽  
Gas Volume

Steam-assisted gravity drainage (SAGD) is the method of choice for producing oil from oil sands reservoirs. In this method, steam is injected into the formation and the oil, upon heating, is mobilized and driven under gravity to a production well. The accumulation of steam within the reservoir is referred to as the steam chamber. One of the critical issues confronting SAGD operators is the thermal efficiency, measured by the steam-to-oil ratio, of their operations since it directly ties to process costs. Using thermocouple profiles from observation wells on three SAGD fields in Alberta, we use error function fits to estimate the thermal conductivity of the shale above the oil formation (found to be from 0.33 to 3.81 W/mK), heat flux at the top of the steam chamber, vertical height of the steam/gas zone above the steam chamber, and accumulated gas volume present. A gas material balance is then derived to estimate the volume of gas that might be generated through in situ chemical processes. The results of the heat transfer analysis performed on the thermocouple data reveal that the gas co-injection during SAGD operations studied did not directly affect the heat transfer rate at the top of the steam chamber since the gas volume added was small. The results also show that a sufficiently large accumulation of gas at the top of the chamber lowers the heat flux at the edge of the chamber.

The Analysis of the Heat Transfer into Reactor Walls in the Thermal System and the Verification

2013 ◽  
Vol 694-697 ◽  
pp. 771-777 ◽  
Author(s):  
Stanislav Honus ◽  
Ondřej Němček ◽  
Dagmar Juchelková
Keyword(s):  
Heat Transfer ◽  
Heat Transfer Analysis ◽  
Thermal System ◽  
Thermodynamic Similarity ◽  
Analytical Results ◽  
Heat Intake ◽  
Thermal Flows ◽  
Heat Transfer By Radiation ◽  
Radiation Laws

The article presents the analysis of thermal flows into reactor walls within the semi-operational pyrolytic system. There were hydrodynamic and thermodynamic similarity theories and heat transfer by radiation laws used for the solution of this issue. The entry data for the heat transfer analysis were gained by conducted experiments. The correctness of the resulting values has been verified by measurements. The required reactor parameters, for the required heat intake, have been derived from the analytical results at the end of this article.

scholarly journals Numerical Simulation on Flow and Heat Transfer in Pulsating Heat Pipe with Different Models

2020 ◽  
Vol 165 ◽  
pp. 01031
Author(s):  
Jian-Hong Liu ◽  
Fu-Min Shang ◽  
Wei Qiao
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Heat Pipe ◽  
Volume Fraction ◽  
Working Fluid ◽  
Gas Velocity ◽  
Pulsating Heat Pipe ◽  
Flow And Heat Transfer ◽  
Gas Volume Fraction ◽  
Gas Volume

Based on Mixture and Euler model, numerical simulation was used to study the flow and heat transfer in pulsating heat pipe by unsteady method. By comparing the gas volume fraction and gas velocity by different models at different time, the results showed that both models could simulate the evaporation and condensation process of the working fluid, and the liquid plug and gas plug were formed in the tube. By comparing the gas volume fraction and gas velocity at 5s and 10s, it was indicated that the fluid dynamics and heat transfer were more violent by Mixture model in the tube.

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