CONVECTIVE HEAT TRANSFER ANALYSIS IN A HELICAL COIL
PRESENT_PPT8
1. THE NEW CONCEPT OF EFFICIENT
WATER PLASMA GENERATORS
• L. Charakhovski1,2, A. R. Marquesi2, C. Otani2, G.Petraconi Filho2, I.
Khvedchyn1, V. Sauchyn1, D. Scomorokhov, R. Bicudo2, A.S. da Silva
Sobrinho2, M. Massi2, H.S. Maciel3, A. Halinouski1,2
•
• 1 Luikov Heat and Mass Transfer Institute-HMTI, Minsk, 220072, Belarus, P. Brovki
15, leonidsh.hmti@gmail.com
• 2 Instituto Tecnologico de Aeronautica -ITA, S. Jose dos Campos, Brazil
• 3 Instituto de Pesquisa e Desenvolvimento –IP&D/UNIVAP, S. Jose dos Campos,
Brazil
2. INTRODUCTION
Water plasma consisting of hydrogen and oxygen is very perspective for many
technologies. The studies of water plasma were initiated long ago, starting from
Gerdien in the 1920s. He attained the temperature of water plasma up to 50000 K
in the arc stabilized by liquid water. Today two concepts of water plasma
generators exist - the first one – Gerdien’s type with water-stabilized arc and the
second – with the arc stabilized by steam. The most known today plasma
generators using first concept were developed successfully in the series of plasma-
torches in Czech Rep. by Prof. Hrabovsky et al. The second concept was developed
in different institutions and countries, however the most extensive and successful
studies were made in the Institute of Theoretical and Applied Mechanics Siberian
Branch of Academy of Sciences USSR and the most powerful plasma steam
torches were developed there by Prof. B. Mikhailov.
3. The main drawback of water-stabilized plasma-torches – non-controllable evaporation of plasma generating water, and
inevitable loss of heat with outlet water making their efficiency about 60% thereby impeding their using for many
technologies.
[1] M. Hrabovsky. Thermal Plasma Generators with Water Stabilized Arc. The Open Plasma Physics
Journal, 2009, 2, 99-104
4. Steam Plasma- torches of the Institute of Theoretical and Applied Mechanics Siberian Branch of Academy of
Sciences [1] B. Mikhailov. “Electric arc generators of steam-water plasma”, P.2, Thermal Physics and Aeromechanics, 2003, Vol.10,
No. 4, pp. 637-657, (in Russian).
Type EDP-215 EDP-217 EDP-211 EDP-201
Power,kW 10-70 60-150 200-500 400-1000
Steam fl.rate,
g/s
0.5-3.0 1.0-5.0 5.0-30 10-60
Current max.,A 250 500 800 800
Efficiency 0.5-07 0.6-07 0.6-0.75 0.7-0.8
Cathode
lifetime, H
30 100 100 100
Anode lifetime,
H
100 300 300 300
Mass,kg 1.25 12.5 42 82
5. Using steam instead of water for stabilizing arc makes it possible principally attaining efficiency of plasma setup about 100% if to use for cooling
of plasma torch only working flow of water and transforming it to steam under proper control just inside the plasma setup and then using for
generating plasma. Prof. B. Mikhailov has built so called auto-plasma-torches EDP-198 and EDP203 with generation of steam just in cooling jacket,
applying its special capillary structure. However even with porous structure the range of performance was found to be too narrow being limited by
steam condensation at low current and superheating at high one. 1. Mikhailov B.I. Regenerating of heat at electric arc steam vortex plasma
torches. Auto plasma torches. Thermo-physics and Aeromechanics, 2005, Vol. 12, No.1, pp. 135-148.
Current – voltage characteristics of EDP-198
6. We attained 97-98% regeneration of heat in our plasma setup (without
anode) by vortex heat shielding the discharge channel without special
water cooling combined with superheating of steam both in external
two-stage generator and in the torch.We show this process in P-h
diagram. Instead of direct superheating steam along the arrow A-B,
followed by non-stable explosive transition water/steam, we at first
heated water in the 1st stage of generator under elevated pressure
about 10 bar without traversing phase boundary, (Point A), then
throttled it to lower pressure about 1-2 bar in the second stage,
crossing thereby phase boundary without heating (arrow A-C) and
continued its quiet superheating in the 2nd stage or in common
cooling jacket with no capillary structure, up to final temperature
200-500 0C, depending on torch regime, along the arrow C-D. 1. B.
Mikhailov, Investigation of fluctuations in steam generating
tubes. Thermophysics and aeromechanics, 1985, Issue2, #10,
pp. 43-47. 2. L. Charakhovski, A. Marquesi, C. Otani,G.
Petraconi Filho, R. Bicudo, A.S. da Silva Sobrinho, M. Massi,
A. Gorbunov, H.S. Maciel. High-Efficient Steam Plasma Torch
– Preliminary Study. In Proc. Of 7th Intern. Workshop and
Exhib. On Plasma Assisted Combustion (IWEPAC), 13-15
September 2011, Las-Vegas, Nevada, USA.
3. L. Charakhovski, A. Marquesi, C. Otani,G. Petraconi Filho,
R. Bicudo, A.S. da Silva Sobrinho, M. Massi, A. Gorbunov,
H.S. Maciel, Steam Plasma Torch with Regenerative Cooling.
In Proc. of 7th Intern. Conf. on Plasma Physics and Plasma
Technology (PPPT-7), 17-21 September 2012, Minsk, Belarus,
pp. 723-726.
7. Transferred arc steam plasma-torch W1 with distributed swirling injection of steam. 1-cathode; 2-auxiliary solenoid-shaped anode;
3-arc; 4-principal vortex chamber with electric insulation. About 50% of steam flow rate is injected by principal vortex chamber,
the rest is distributed along the discharge channel. Steam is supplied at first for preheating jacket surrounding cathode 1, then
is injected tangentially and continuously in counter-flow inside of discharge channel, stabilizing the arc and protecting the walls
of channel from hot arc plasma.
8. We applied then the novel scheme of arc vortex stabilization with aerodynamic twist of flow in the spiral channels
outside the discharge channel and the transfer of the vortex inside the channel through special slits in the walls. This
channel is able working both with dry and wet steam without water cooling. It provided also by special two-stage
throttling direct-flow steam generator. 1. Charakhovski L.I., Charakhovski A.I., Inter-electrode insert of plasma torch. Pat.
Rep. Belarus # 16787, H 05H1/00; B01J 19/08, 24.08.2010; Publ. Bulletin NCIP RB #1 , 30.12. 2011.
10. Tubular-shaped technological torch TS1 with no outside electric insulation. About 50% of steam flow is also
injected by principal inter-electrode gap, the rest is distributed along the discharge channel.
12. Temper colors of the steel nozzle of the torch TS1 after operation during 0.5 hour
with air plasma. We see that hottest zone was near inter-electrode gap (black) and
coldest one – near outlet of plasma jet (yellow).
13. Plasma torch TS2 for 300 kW power with solenoidal auxiliary anode at laboratory
workbench.
22. Schematic of pneumatic and electric circuit of TS2 applied for testing at remote
reactor about 5 m distance from the steam generator .
23. The record of temperatures at inlet and outlet of the pipeline of steam of the length
of 5m during testing. Pipeline was connected in series electrically with the 2nd stage
of steam generator.
24. By feedback from thermocouples 6,7,8 we were able to set temperature
limit at chosen point at plasma setup. 1–power suppl. of the 1st stage; 2-
1st stage; 3 - throttle; 4 - 2nd stage; 5 -power suppl. of the 2nd stage; 6,7,8
– inlet, nozzle and cathode thermocouples.
25. Reaction
chambers Refractory
Steel
hermetic
body
Metal
Power supply
Steam
Slag
V
1
1- Electric arc; 2-3 – Molten electrodes; 4-dielectric
separation; 5-water-cooled channel.
So, it is possible attaining perfect insulation of the discharge channel from plasma, however electrodes have to be
contacting directly with plasma and closing electric circuit. Therefore Prof. M.R. Predtechenski M.R. from the Institute of
Thermophysics SB RAS proposed Plasma-chemical reactor with renewable molten electrodes placed just in the reactor. 1.
M.R. Predtechenski. Pat USA 6 846 467, B1, Publ. Jan 25, 2005. 2. M.R. Predtechenskii, O.M. Tukhto. Plasma Torch with
Liquid Metal Electrodes. High Energy Chemistry.2006. Vol. 40, No.2, P. 119-124.3.
http://www.sibai.ru/plazmoximicheskaya-texnologiya-unichtozheniya-opasnyix-otxodov.html
26. They used water-cooled discharge channel and attained 90% efficiency of channel without heat loss to
electrodes in the reactor. These 10% can be regenerated also according to our experiments, where we
obtained 97% efficiency during experiments in plasma reactor and these 3% were measured as heat loss
at cathode. L. Charakhovski, A. R. Marquesi, C. Otani, G.Petraconi Filho, R. Bicudo, A.S. da Silva Sobrinho,
M. Massi, H.S. Maciel, A. Gorbunov, A. Halinouski. Water steam plasma equipment // In Proc. Of 8th
Intern. Conference on Plasma Technologies (ICPAT8), 18-21 February 2013, Rio de Janeiro, Pp. 48-51.
The record of efficiency of torch TS2 with W cathode
during testing at big laboratory reactor without heat loss
from the bottom electrode.
27. We adjusted steam plasma-torches including ones with molten electrodes for operation with
no cooling other than plasma generating steam flow. Due to absence of cooing jacket the
discharge channel can be bent easily even ready-assembled. 1. Charakhovski L.I.,
Charakhovski A.I., Water Steam Plasma Torch and its Cooling Method. Pat. Rep. Belarus
#19100,08.08.2012; Publ. Bulletin NCIP RB #2, 30.04. 2014.
28. The torch with
evaporative cooling of
anode by wet steam
at pressure about 2
bar and temperature
120C instead of water
cooling. Cooling jacket
is connected in series
between the 1st and
2nd stages of steam
generator.
