A design method of an S-curved parabolic trough collector absorber with a three-dimensional heat flux density distribution

Solar Energy ◽  
2015 ◽  
Vol 122 ◽  
pp. 873-884 ◽  
Author(s):  
Yassine Demagh ◽  
Ilyes Bordja ◽  
Yassine Kabar ◽  
Hocine Benmoussa
2010 ◽  
Vol 143-144 ◽  
pp. 1439-1444
Author(s):  
Jian Bing Meng ◽  
Xiao Juan Dong ◽  
Wen Ji Xu

A theoretical analysis was carried out to investigate the characteristics of atmospheric pressure plasma arc injected transverse to a transverse alternating magnetic field and a mathematical model was developed to describe the heat flux density distribution of the plasma arc. The effect of processing parameters, such as flow rate of working gas, arc current, magnetic flux density and the standoff from the nozzle to the workpiece, on the heat flux density distribution of plasma arc were also analyzed. The results show that it is feasible to adjust the heat flux density of the plasma arc by the transverse alternating magnetic field, which can expand the region of plasma arc thermal treatment and flatten the heat flux density upon the workpiece. With the magnetic flux density enhancing, the heat flux density gradient upon the workpiece decreases. Under the same magnetic flux density, the more gas flow rate and arc current, the more heat flux density peak increase. Contrarily, more distance from nozzle outlet to workpiece descends the heat flux density peak.


2014 ◽  
Vol 8 (1) ◽  
pp. 387-395 ◽  
Author(s):  
Xiaojuan Dong ◽  
Jianbing Meng ◽  
Xiuting Wei ◽  
Zhanmin Yin

An external transverse-alternating magnetic field with sinusoidal and triangular alternating currents was applied to a combined plasma arc to create a plasma arc for expanding the cross section of arc column and flatting the distributions of arc temperature. Two mathematical models were developed to describe the heat flux density distributions of the combined plasma arc driven by a transverse-alternating magnetic field with sinusoidal and triangular alternating currents. The behavior of plasma arc under the external transverse-alternating magnetic field imposed perpendicular to the plasma current was discussed theoretically and experimentally by changing various parameters such as working gas flux, arc current, magnetic flux density including its wave form and the standoff from the nozzle to the workpiece. The analytical results show that it is feasible to adjust the shape and heat flux density of the combined plasma arc by the transverse- alternating magnetic field, which expands the region of combined plasma arc thermal treatment and uniforms the heat flux density upon the workpiece. Changing the waveform of the alternating current can also control the heat flux density distribution. As well as, calculated heat flux density distributions of combined plasma arc driven by the external transverse-alternating magnetic field show a good agreement with experimental data. The magnetic field with triangular alternating current can flat the heat flux density distribution on the anode rather than sinusoidal one. This approach to flat the heat flux density distribution on the anode surface will give an effective controllability to the combined plasma arc application.


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