254 nm Radiant Efficiency of High Output Low Pressure Mercury Discharge Lamps with Neon-Argon Buffer Gas

2013 ◽  
Vol 325-326 ◽  
pp. 409-412
Author(s):  
Hao Jun Zhang ◽  
Qiu Yi Han ◽  
Shan Duan Zhang
Keyword(s):  
Mercury Vapor ◽  
Low Pressure ◽  
Input Power ◽  
Cold Spot ◽  
Outer Diameter ◽  
Buffer Gas ◽  
Uv Irradiance ◽  
Radiant Efficiency ◽  
Uv Lamps ◽  
High Output

High output low pressure mercury (LPM) discharge UV lamps have been briefly introduced. In order to measure the 254 nm radiant efficiency simply and preciously, Keitz formula was used and its advantage was illustrated. The LPM lamps had outer diameter of 19 mm (T6). The buffer gases are neon (65%) and argon (35%) with total pressure 1-10 Torr (133-1333 Pa). The lamps were operated with cold spot temperatures from 20°C to 80°C and discharge current from 0.8 A to 2.0 A. The electric field, input power, 254 nm UV irradiance and irradiance of other Hg lines from 265 to 579 nm in positive column were measured. The radiant power of each wavelength can be calibrated according to the 254 nm output and the Keitz formula. It was shown that the radiant efficiency of 254 nm can reach a maximum of above 40% at cold spot temperature 45-47 °C and current 1.6 A for filling pressure less than 3 Torr. The optimal mercury vapor pressure was 1.2 to 1.4 Pa. The output percentage of other Hg lines was below 5%. With the decrease of buffer gas pressure, the 254 nm radiant efficiency increased obviously.

Strong Lines Emitted from Positive Column of Narrow Bore T2 Low-Pressure Ar-Hg Discharges

2013 ◽  
Vol 325-326 ◽  
pp. 405-408 ◽  
Author(s):  
Qiu Yi Han ◽  
Shan Duan Zhang
Keyword(s):  
Vapour Pressure ◽  
Positive Column ◽  
Electrical Power ◽  
Low Pressure ◽  
Cold Spot ◽  
Outer Diameter ◽  
Lamp Product ◽  
Radiant Efficiency ◽  
Radiant Power ◽  
Spot Temperature

The electric field and absolute radiance of 13 strong lines in the positive column of narrow bore T2 (outer diameter 7 mm) low-pressure Ar-Hg discharges were measured experimentally, which includes 11 Hg lines ranging from 185 to 579 nm and 2 Ar lines of 811, 842 nm. The discharges were operated with different argon filling pressure ranging from 2 to 10 Torr (corresponding to 266 to 1333 Pa), for discharge currents 20-200 mA and cold spot temperature 20-80 °C (0.16-11.8 Pa Hg vapour pressure). The Koedam factors of important emission lines were also measured for various discharge parameters, in order to convert radiance to exitance, whereafter the radiant power of all the lines except 185 nm, could be calculated and their radiant efficiency could be compared as well. Considering the absorption of 185 nm radiation in air, the ratio of the radiance at 185 nm to that at 254 nm was measured instead of its Koedam factor for current 80-200 mA and cold spot temperature 20-60 °C. Therefore, 185 nm radiant power was derived indirectly from that of 254 nm in corresponding discharge conditions. According to our measured results, the argon pressure for the maximum production of 254 nm radiation is around 5 Torr. It is showed that the optimum cold spot temperature for 254 nm radiant efficiency is higher than 50 °C, which is consistent with the temperature dependence on the tube diameter. With increasing discharge current and cold spot temperature, 185 nm radiant power has the similar tendency to that of 254 nm, while the fraction of electrical power converted to 185 nm radiation increases slightly with these parameters. Generally, the ratio of radiant power at 185 nm to that at 254 nm is higher than 0.2. For evaluating the energy balance of the positive column as well as the luminous efficacy of the fluorescent lamp product, the radiant powers of other strong lines also has significantly effect though they are considerably smaller than that of 254 nm and 185 nm. Besides, it must be taken in consideration that mercury depletion on the axis of positive column is serious for T2 narrow tube discharge especially at low Hg vapour pressure and high current.

scholarly journals Laboratory Investigation of Inorganic Fouling of Low Pressure UV Disinfection Lamps

2001 ◽  
Vol 36 (1) ◽  
pp. 71-92 ◽  
Author(s):  
M. Sheriff ◽  
M. Gehr
Keyword(s):  
Uv Light ◽  
Low Pressure ◽  
Bulk Precipitation ◽  
Batch Tests ◽  
Uv Irradiance ◽  
Theoretical Predictions ◽  
Flow Through ◽  
Inorganic Constituents ◽  
Uv Lamps ◽  
Solids Deposition

Abstract Iron(III) (mainly dosed as FeCl3) is one of the main inorganic constituents associated with the fouling of UV lamps during disinfection of wastewater. A low pressure mercury lamp UV system was operated under laboratory conditions to assess the effects of heat and UV light on fouling. Iron(III) was dosed at different concentrations and fouling was monitored by measuring the UV irradiance. The potential for ferric phosphate fouling and the effects of organics were also studied. Results showed that fouling did not occur in recirculating systems over 12 days of observation. However, in flow-through systems, the extent and rate of fouling depended on the solution Fe concentration. Furthermore, addition of phosphorus increased the fouling rate. Bulk precipitation appeared to be significant at iron(III) dosing over 3 mg/L. Theoretical predictions of an equilibrium model (MINEQL+) showed similar trends with measured concentrations of soluble Fe and P from batch tests. However, model predictions of temperature effects alone could not account for the observed solids deposition on the quartz sleeve. Bulk precipitation, followed by sedimentation, was considered to be the dominant mechanism at high iron (III) concentrations.

A Preliminary Study of the Erosion Process in Micro-Machining of Glasses with a Low Pressure Slurry Jet

2008 ◽  
Vol 389-390 ◽  
pp. 375-380 ◽  
Author(s):  
Thai Nguyen ◽  
King Pang ◽  
Jun Wang
Keyword(s):  
Fluid Flow ◽  
High Surface ◽  
Low Pressure ◽  
Outer Diameter ◽  
Micro Machining ◽  
Erosion Process ◽  
Machined Surface ◽  
High Surface Quality ◽  
Accumulation Zone ◽  
Micro Hole

The erosion process in micro-machining of brittle glasses using a low pressure slurry jet is discussed. The process capability of the technique is assessed by examining the machined surface integrity in relation to fluid flow dynamics in micro-hole generations. The holes produced are characterised by a “W” shape in the cross section, while the surface morphology is distinguished by three zones associated with the fluid flow behaviour, i.e. a direct impact zone, a wavy zone and an accumulation zone. The surfaces appear to be smooth and without cracks, indicating a predominance of the ductile mode erosion process. With the increase of pressure, the erosion rates can be enhanced as a result of the expending of the accumulation zone while the outer diameter of the holes remains unchanged. This study shows that this technique can be used for micro-machining with high surface quality, and provides an essential understanding for further research in the avenue.

scholarly journals Catalytic and Noncatalytic Conversion of Methane to Olefins and Synthesis Gas in an AC Parallel Plate Discharge Reactor

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Mohammad Ali Khodagholi ◽  
Mohammad Irani
Keyword(s):  
Synthesis Gas ◽  
Parallel Plate ◽  
Discharge Plasma ◽  
Ambient Pressure ◽  
Direct Conversion ◽  
Gas Discharge ◽  
Input Power ◽  
Outer Diameter ◽  
Gas Discharge Plasma ◽  
Conversion Of Methane

Direct conversion of methane to ethylene, acetylene, and synthesis gas at ambient pressure and temperature in a parallel plate discharge reactor was investigated. The experiments were carried out using a quartz reactor of outer diameter of 9 millimeter and a driving force of ac current of 50 Hz. The input power to the reactor to establish a stable gas discharge varied from 9.6 to maximum 15.3 watts (w). The effects of ZSM5, Fe–ZSM5, and Ni–ZSM5 catalysts combined with corona discharge for conversion of methane to more valued products have been addressed. It was found that in presence or absence of a catalyst in gas discharge reactor, the rate of methane and oxygen conversion increased upon higher input power supplied to the reactor. The effect of Fe–ZSM5 catalyst combined with gas discharge plasma yields C2hydrocarbons up to 21.9%, which is the highest productions of C2hydrocarbons in this work. The effect of combined Ni–ZSM5 and gas discharge plasma was mainly production of synthesis gas. The advantage of introducing ZSM5 to the plasma zone was increase in synthesis gas and acetylene production. The highest energy efficiency was 0.22 mmol/kJ, which belongs to lower rate of energy injection to the reactor.

Method to determine the power efficiency of UV disinfection plants and its application to low pressure plants for drinking water

2016 ◽  
Vol 17 (4) ◽  
pp. 947-957 ◽  
Author(s):  
Alois W. Schmalwieser ◽  
Georg Hirschmann ◽  
Alexander Cabaj ◽  
Regina Sommer
Keyword(s):  
Drinking Water ◽  
Electric Power ◽  
Power Efficiency ◽  
Electrical Power ◽  
Low Pressure ◽  
Uv Disinfection ◽  
Plant Type ◽  
Uv Irradiance ◽  
Flow Through ◽  
Selection Of

In this paper we present a method to determine the power efficiency of ultraviolet (UV) disinfection plants and apply this to low pressure plants for drinking water. In UV disinfection plants the water flow is regulated to ensure that microorganisms receive the necessary fluence for inactivation while passing through. The flow depends on the UV transmission (UVT) of the water. The lower the UVT of the water is, the less water may flow through the plant. UV irradiance is produced by lamps that consume, together with other components, electrical power and entail running costs. The power efficiency – electrical power versus disinfected volume – of a plant has therefore an important impact. Applying this method to different UV plants that are on the market shows that electric power of at least 5.3 Wh is necessary to disinfect 1 m3 of water possessing a UVT of 80% (100 mm), 8 Wh at 50% and 22 Wh at 10%. Further we found that ineffective design or a wrong selection of a plant may enhance these values by a factor of up to 7. This method enables not only the calculation of the power efficiency but also the decision for a certain plant type.

Comparison of Low Pressure and Medium Pressure UV Lamps for UV/H2O2Treatment of Natural Waters Containing Micro Pollutants

2010 ◽  
Vol 32 (5) ◽  
pp. 329-337 ◽  
Author(s):  
Guus F. IJpelaar ◽  
Danny J.H. Harmsen ◽  
Erwin F. Beerendonk ◽  
Robin C. van Leerdam ◽  
Debbie H. Metz ◽  
...  
Keyword(s):  
Natural Waters ◽  
Low Pressure ◽  
Medium Pressure ◽  
Uv Lamps ◽  
Micro Pollutants
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