REACTOR’S THERMOPHYSICAL CHARACTERISTICS WITH AN ELECTROTHERMAL FLUIDIZED BED AND A COMBINED HEATING METHOD

2018 ◽  
pp. 59-66
Author(s):  
K.V. Simeiko ◽  
M.A. Sidorenko
Keyword(s):  
Heat Exchange ◽  
Fluidized Bed ◽  
Quartz Sand ◽  
Pyrolytic Carbon ◽  
Dielectric Materials ◽  
Similarity Criteria ◽  
Calculation Methods ◽  
National Academy Of Sciences ◽  
Heating Method ◽  
Pure Silicon

To improve the technological features and efficiency of high-temperature processing of the dielectric materials, a reactor design with the electrothermal fluidized bed with a combined heating method was developed at the Institute of Gas of the National Academy of Sciences of Ukraine. The main purpose of this reactor is the process of applying a pyrocarbon coating to quartz sand. The principle-technological scheme of the process is given. Subsequently, quartz sand coated with pyrolytic carbon will be used to produce pure silicon carbide. The authors developed a methodology for calculating the heat balance, which allows estimating the efficiency of the reactor. A method for calculating similarity criteria was chosen for the possibility of comparing the efficiency of heat exchange in a developed reactor with other machines for thermochemical processes. A description of the heat exchange between the fluidized bed and the electrode is proposed. After further experiments, it willbe possible to make final conclusions regarding improving the technological features andincreasing the efficiency of the process of applying a pyrolytic coating to quartz sand, andalso to check the adequacy of the calculation methods. After further experiments, it will bepossible to make final conclusions about improving the technological features and increasing the efficiency of the process of applying a pyrolytic coating to quartz sand. Also, it will allow to check the adequacy of the calculation methods. Bibl. 17, Fig. 2.

Solids Flow Pattern in the Bottom Zone of a Rectangular Cross-Section Circulating Fluidized Bed

2003 ◽  
Author(s):  
Hong-Shun Li ◽  
Yi-Jun Wang ◽  
Shi-Ping Jin
Keyword(s):  
Flow Pattern ◽  
Fluidized Bed ◽  
Cross Section ◽  
Quartz Sand ◽  
Circulating Fluidized Bed ◽  
Rectangular Cross Section ◽  
Temperature Response ◽  
Cold Model ◽  
Hot Particles ◽  
Bottom Zone

Solids flow pattern in the bottom zone of a rectangular cross-section CFB was investigated by using hot particles as the tracer. The experiments were carried out in a cold model circulating fluidized bed. The riser has an inner cross-section of 0.3 m by 0.5 m and a height of 5.8 m. The solids were returned into the riser at a height of 0.75 m above the air distributor within an angle of about 40 degree. Quartz sand was used as the bed material. The hot particles were also quartz sand but with a little smaller size. Specially designed miniature electrically heating devices were installed flush with the inner bed wall or inside the bed. At each run, about 10–15 cm3 hot particles were slowly pulled into the bed. The temperature response around the device was measured with four copper-constantan thermocouples. Based on the experimental results, a 3-D core-annulus model describing the solids flow pattern in the bottom zone of the CFB riser is proposed.

CFD-DEM Numerical Simulation and Experimental Validation of Heat Transfer and Two-Component Flow in Fluidized Bed

2017 ◽  
Vol 16 (1) ◽  
Author(s):  
Feihong Guo ◽  
Zhaoping Zhong
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Fluidized Bed ◽  
Quartz Sand ◽  
Thermal Imager ◽  
Gas Velocity ◽  
Bed Height ◽  
Two Component ◽  
Superficial Gas Velocity ◽  
Infrared Thermal Imager

AbstractBased on the improved computational fluid dynamics and discrete element method (CFD-DEM), heat transfer and two-component flow of biomass and quartz sand have been studied from experiments and numerical simulation in this paper. During experiments, the particle temperature and moving images are respectively recorded by infrared thermal imager and high speed camera. With the increase of the velocity, the mixing index (MI) and the cooling rate of the particles are rising. Due to larger heat capacity and mass, the temperature of biomass drops slower than that of quartz sand. Fictitious element method is employed to solve the incompatibility of the traditional CFD-DEM where the cylindrical biomass are considered as an aggregation of numerous fictitious sphere particles arranged in certain sequence. By the comparison of data collected by infrared thermal imager and the simulated results, it can be concluded that experimental data is basically agreement with numerical simulation results. Directly affected by inflow air (25℃), the average temperature of particles in the bed height area (h>30 mm) is about 3 degrees lower than that of the other heights. When the superficial gas velocity is larger, the fluidization is good, and the gas temperature distribution is more uniform in the whole area. On the contrary, bubbles are not easy to produce and the fluidization is restricted at lower superficial gas velocity. Gas-solid heat transfer mainly exists under the bed height of 10 mm, and decreases rapidly on fluidized bed height. The mixing index (MI) is employed to quantitatively discuss the mixing effectiveness, which first rises accelerate, then rising speed decreases, finally tends to a upper limit.

scholarly journals INFLUENCE OF SURFACE HEATING TEMPERATURE ON EXTERNAL HEAT-EXCHANGE IN WET VIBRO-FLUIDIZED BED

2018 ◽  
Vol 59 (5) ◽  
pp. 77
Author(s):  
Boris G. Sapozhnikov ◽  
Anastasiya M. Gorbunova ◽  
Yuliya O. Zelenkova ◽  
Nina P. Shiryaeva
Keyword(s):  
Heat Transfer ◽  
Experimental Data ◽  
Heat Transfer Coefficient ◽  
Heat Exchange ◽  
Fluidized Bed ◽  
Heating Temperature ◽  
Heating Surface ◽  
External Heat ◽  
Porous Particles ◽  
External Heat Transfer

Experimental data are given on the influence of the temperature of the heating surface, placed to a wet vibro-fluidized bed of non-porous particles, and higher that the saturation temperatures on the external heat-transfer coefficient at conductive supply of the heat.

scholarly journals Fluidized bed heat exchange capacity of Alumina, coal-char and bio-char solids

2018 ◽  
Vol 414 ◽  
pp. 012003
Author(s):  
F Mushtaq ◽  
I Ullah ◽  
I Khan ◽  
S K Sami ◽  
W Alam ◽  
...  
Keyword(s):  
Heat Exchange ◽  
Fluidized Bed ◽  
Exchange Capacity ◽  
Coal Char

scholarly journals Identification of the Building Envelope Performance of a Residential Building: A Case Study

Energies ◽  
2020 ◽  
Vol 13 (10) ◽  
pp. 2469
Author(s):  
Evi Lambie ◽  
Dirk Saelens
Keyword(s):  
Heat Exchange ◽  
Real Life ◽  
Residential Building ◽  
Poor Performance ◽  
Energy Performance ◽  
Building Envelope ◽  
Calculation Methods ◽  
Characterization Methods ◽  
Target Values

Since households are one of the most energy-intensive sectors in Europe, retrofit of dwellings is promoted to increase energy efficiency. Recent research, however, shows that the energy performance after retrofit does not always meet the target values, which can be caused by amongst other things, a deviating building envelope performance. This paper compares the theoretical and measured building envelope performance for a real-life case study in post-retrofit state, in order to illustrate the limitations of calculation methods and characterization models. First, the performance is evaluated on building scale by verifying the correspondence between the default theoretical heat loss coefficient (HLC) and the measured HLC, which was determined by following the guidelines formulated within IEA EBC Annex 58 and Annex 71. In order to illustrate the limitations of the standard calculation method in real-life conditions, the theoretical variability of the HLC is evaluated, generated by variating infiltration heat losses and heat exchange with neighboring dwellings. Second, the performance is investigated on a component scale by assessing the theoretical and measured thermal resistances, identified from heat flux tests. Additionally, nonhomogeneous assembled components and air leaks are simulated to verify probable causes for the locally varying measured values and to illustrate the limitations of calculations and characterization methods. The results illustrate the limitations of the calculation methods by the assessment of the strong variability of the theoretical HLC, depending on assumptions regarding infiltration and heat exchange with neighboring dwellings. In addition, component simulations indicated that deficiencies on a component scale could be caused by a nonhomogeneous assembly and air cavity flows of the component. Moreover, a detailed assessment of an unreliable thermal resistance illustrates the limitations of the used characterization method. Finally, a contrast was found between the quite good performance on building scale (15% deviation between the theoretical and measured HLC) and poor performance on a component scale (only one out of nine monitored components met their theoretical target values), which illustrates the complexity of the building envelope performance.

A new type of district heating method with co-generation based on absorption heat exchange (co-ah cycle)

2011 ◽  
Vol 52 (2) ◽  
pp. 1200-1207 ◽  
Author(s):  
Yan Li ◽  
Lin Fu ◽  
Shigang Zhang ◽  
Yi Jiang ◽  
Zhao Xiling
Keyword(s):  
Heat Exchange ◽  
District Heating ◽  
Heating Method ◽  
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