Lamp Length Research Articles

Two-dimensional Keitz method for the radiant power measurement of planar ultraviolet excilamps

Planar XeBr∗ and XeCl∗ excilamps emitting noncoherent narrowband UVB light (280–315 nm) are now widely used to cure psoriasis and vitiligo as well as to improve vitamin D synthesis. The two-dimensional integral formula has been deducted in this study, which is a good method and has great practical significance to calculate the total radiant power and assess the energy efficiency of a planar UV lamp. The measured radiant power of planar white LED lamps through a two-dimensional Keitz formula has been compared to that of gonio-photometer, verifying the applicability of the formula. The optimum measurement distance is dependent on the lamp length (1.5L≤D≤3.5L) for which the derivation from the two methods can be controlled within 10%. The planar XeBr∗ excilamps have been measured and compared to coaxial excilamps, which show similar patterns of change for the radiant characteristics. Since the planar radiant power formula only needs to measure normal illuminance at a certain distance from the symmetric center of the lamp, it is more convenient to use and is a low-cost method to promote the development of large-sized planar ultraviolet lamps.

Rationale for Parameters of Energy-Saving Illumination inside Agricultural Premises and Method of Its Values Calculation

High-quality lighting of premises in the cultivation of farm animals is an important condition for the successful development of the agro-industrial complex. Sufficient lighting with the simulation of sunrise and sunset which increases daylight hours to 15–16 h can raise the level of production by 8–15%. The most innovative, economical and efficient light source for livestock, poultry and greenhouse buildings are LED lamps allowing for a short payback period. The difference between the models developed by the authors and the traditional point method is taking into account lamp length o, lamp suspension height, location of the illuminated area under the lamp at displacement and observation angles, and luminous flux of light source, and the most important thing is body angle of the light source. This paper presents the method for calculating illumination under the LED lamp due to the large error in the values obtained by theoretical methods due to the lack of a correction factor for changing the illumination of the lamp (0.8). Prediction of crystal heating was carried out by verification calculation in the ANSYS/CFX software package. Forecasting the illumination of the fodder table was carried out by calculation in the DIALux evo software package. The main parameters of an energy-saving LED lamp (power consumption, luminous flux, color temperature and color) were selected. The consumption of electrical energy decreased by 85%; the average level of illumination increased and amounted to 123.1 lux. The developed method for calculating the illumination under the LED lamp can be considered satisfactory, the Student and Fisher criteria do not exceed tabular values and the correlation coefficient showed a close relationship. To comply with electrical safety standards in the premises, a resonant power supply system for LED lamps is offered.

A Refinement Of The Determination Method Of The Linear low-pressure Uv Lamps Radiant Flux

For the measurement of linear low-pressure UV lamps radiant flux the method proposed by the IUVA, which is based on the Keitz method, has become widely used. For deriving the equation that connects the irradiance generated by a lamp at a close distance and its radiant flux, the authors of the method presume that the lamp is the cylinder of equal radiance. According to our estimates, this assumption leads to the inaccuracy of 3 % to 5 % with respect to goniophotometric measurements. In this research, a general formula is derived that connects the irradiance generated by a linear emitter and its radiant flux. This formula does not impose restrictions on the radiant intensity curve in the longitudinal plane. The Keitz equation is its particularcase. To reduce the inaccuracy of the IUVA method, the angular distribution of the radiant intensity of the UV lamps is proposed to be approximated by a cosine polynomial. In order to find the coefficients of the polynomial,clarify the Keitz formula, as well as to estimate the inaccuracy of the refined and classical versions of this formula, the series of goniophotometric measurements of the DB15, DB18, DB30 lamps at various distances was carried out. It was found that at a scanning step Δθ = 5° the first 9 terms of the trigonometric expansion are sufficient to describe the radiant intensity curve with accuracy satisfactory for practical use. It was also shown that the Keitz method needs to be refined only on the basis of goniophotometric data obtained upon condition r / l ≥ 6 where r is the test distance, l is the lamp length. It was identified that in the case of a differentiated approach, the approximation of the low-pressure UV lamps radiant intensity curve by a cosine polynomial makes it possible to provide an inaccuracy of simplified methods that does not exceed 1 % in relation to the goniophotometric method. It is in dicated that in order to find a universal factor applicable for the entire range of linear low-pressure UV lamps, the development and the analysis of statistical data is required.

Characterization and effectiveness of short-wave ultraviolet irradiation reactors operating in continuous recirculation mode to inactivate Saccharomyces cerevisiae in grape juice

Short-wave ultraviolet (UVC) irradiation is an emerging process that has been reported as an effective method for inactivating bacteria that contaminate water. Research regarding this technology in foods has focused on treating certain liquids inoculated with particular target microorganisms. We evaluated different UVC reactor arrangements with recirculation to inactivate Saccharomyces cerevisiae in grape juice. Tested juice was inoculated with S. cerevisiae and processed at three flow rates (5.2, 17.1, or 31 mL/s) during 60 min. Selected arrangements of UVC reactors were assessed by varying the length (30 or 80 cm) of the UVC lamp (254 nm), the number of lamps (1 or 2), and the thickness of the gap in the reactor (1.0 or 0.5 cm) for the 30 cm UVC lamp. Additionally, UVC dosages of studied arrangements were evaluated through dye degradation in order to determine the effect of flow rate in the recirculating systems. In UVC reactors consisting of a single lamp, approximately 2.5 log-cycle reductions were achieved with flow rates of 17.1 or 31 mL/s, whereas at 5.2 mL/s only 2 log-cycle reductions were attained. With two UVC lamps in series, 5 log-cycle reductions were achieved after 45 min of treatment regardless the length of the lamp but only at the high flow rates tested. With the reactor of the smallest tested thickness, 6 log-cycle reductions were achieved at 17.1 mL/s or 31 mL/s. In general, reduction of juice film thickness allowed greater reductions of S. cerevisiae; furthermore, important differences were observed among the evaluated systems when comparing the effect of flow rate.

Lamp emission and quartz sleeve modelling in slurry photocatalytic reactors

Modelling of incident radiation intensity in a reaction medium or at catalyst surface is a necessity for kinetics modelling of pollutant degradation in photocatalytic reactors. In slurry photoreactors, the incident radiation within the reacting medium is calculated via the radiative transport equation (RTE) which considers the absorption and scattering of light due to the catalyst particles. As a result, a proper lamp emission model is required so as to obtain boundary conditions of the incident radiation entering the reacting medium. In this paper, we examine the validity of line, surface and volumetric source models at describing the incident radiation around a UV lamp. We then examine the effects of different lamp length to lamp radius ratios (2L/rlamp) and lamp ageing on the lamp emission model, with respect to the more descriptive and accurate volume source model. Finally, computational fluid dynamics (CFD) simulations are performed to determine the effect of light reflection, refraction and absorption at the air–quartz–water interfaces on incident radiation entering the reaction medium, for three quartz tube radius to lamp radius ratios (rquartz/rlamp) and two typical quartz tube thicknesses. The results obtained in this study are conveniently presented in dimensionless form and could be used as correction factors in the setting up of the radiation boundary condition in the modelling of cylindrical slurry photocatalytic reactors.

Numerical Study on Transient Heat Transfer of a Quartz Lamp Heating System

Thermal ground testing is an accepted and frequently used method for simulating the aerodynamic heating of high speed flight vehicles. A numerical method based on a finite volume method for a quartz lamp heating system, used in thermal testing, is proposed. In this study, the unstructured finite-volume method (UFVM) for radiation has been formulated and implemented in a fluid flow solver GTEA on unstructured grids. For comparison and validation of the proposed method, a 2D furnace with cooling pipes was chosen. The results obtained from the proposed FVM agreed well with the exact solutions. Numerical results show that the quartz lamp can be simplified as a slat with the same temperature radiation source, and a simplified 2D thermal testing case was then simulated with the coupling effects of radiation, convection, and conduction heat transfer. Different temperature loading curves and ratios of intervals between the lamps and lamp length (l/s) were studied using the proposed method. The radiation heat flux on the metal surface was a wave-shaped curve. Comparing the different interval ratios, we found that the smaller the interval ratio, the larger the maximum value and the smaller the difference between the maximum and minimum heat flux.

P‐82: Super‐Length External‐Electrode Fluorescent Lamps

AbstractThe lamp length 0.6∼2.0 m of external electrode fluorescent lamps for the backlight of LCD‐TVs has been investigated with respect to the lamp property, such as the current and voltage, the luminance and efficiency, and the luminance uniformity along the tube.

2D-LSPP: An Improved Line Source with Parallel Plane Emission (LSPP) Model for Photon Distribution in Annular Reactors

A new class of models-two-dimensional line source with parallel plane emission, or 2D-LSPP-has been proposed for estimation of photon incidence in annular reactors. These models are similar to the well-known line source with parallel plane emission (LSPP) radial model, but these incorporate the axial distribution of photons at the boundary condition (i.e., at the reactor inner wall), which is a characteristic of the line source with spherical emission (LSSE) model. The new models have the advantage of easy implementation in numerical schemes, because only the radial direction must be considered during the calculations. Photon losses through the upper and lower cross-sectional cores are also automatically taken into account, as a function of the lamp length and the system geometry, which is a desirable model property in scale-up procedures that does not exist in the classical LSPP model. In this work, these new models are derived and simulation results are shown for comparison with the LSSE model. Some advantages of the new models are discussed, as well as their application limits.

26.3: High-Performance EEFL Backlight System for Large-Sized LCD-TV

We suggest the novel EEFL (External Electrode Fluorescent Lamp) Backlight System 3 types; the first aspect is a high optical efficiency second is reduction of mechanical size of Backlight, and the last is low power consumption in large LCD Backlight System. To gain a high optical efficiency, we consider the narrow diameter (φ 3.0) lamp of EEFL Backlight System. As the impedance of the narrow diameter (φ 3.0) lamp is higher than that of conventional (φ 4.0) EEFL. A high impedance of lamp is caused the increase of power consumption and a driving voltage of lamp. But its characteristic of an enhancement luminance could be possible for a high optical efficiency. We introduce a method for decrease of a mechanical size for large Backlight. The length of electrode for EEFL system must be increased as a small diameter and a long length of lamp. For that reason is caused the increase of Bezel Size For LCD TV. In this paper, we suggest a DEFL(Differential Diameter External Electrode Fluorescent Lamp). DEFL is made by junction between φ 4.0mm glass tube of emission part and φ 8.0mm glass tube of electrode part. Finally we explain φ 4.0mm EEFL system for low power consumption in comparison with φ 4.0mm CCFL backlight system.

Effects of the H2O2 concentration and spectral distribution of the UV lamp output power on the photooxidation of a water pollutant

Previous kinetics studies have been extended to analyze some practical issues concerning this process. Hence, in this work we have studied additional aspects of the H2O2 enhanced, UV degradation of 2,4-dichlorophenoxyacetic acid (2,4-D), namely: (i) the effect of the H2O2/2,4-D initial molar ratio and (ii) the effect of the irradiation power and, particularly, the characteristics of the wavelength distribution of the lamp output emission. The work was done on a well stirred, discontinuously operated tank reactor irradiated from its bottom. A UV, tubular lamp and a cylindrical reflector of parabolic cross section were used [actually, two germicidal lamps (254 nm) of different output power per unit lamp length and a medium pressure, mercury arc lamp with polychromatic emission between 220 and 760 nm]. 2,4-D concentration and TOC were the main variables used to investigate the degradation rate. There is an optimal initial concentration ratio for each 2,4-D initial concentration. It was also observed that increasing the lamp output power at 254 nm (output from 0.08 W/cm to 0.6 W/cm) favors the reaction rate. However, much more significant is the effect produced by employing a polychromatic lamp with some emission below 254 although this photonic contribution is relatively small (just 0.21 W/cm below 250 nm). A kinetic model, having parameters independent of the reactor configuration and derived from mechanistic considerations was used to analyze the experimental data.

Photomineralization of n-alkanoic acids in aqueous solution by photocatalytic membranes. Influence of radiation power

The TiO2-mediated photomineralization of 8–1000 ppm of methanoic acid, of 6–100 ppm of ethanoic acid. of 6–180 ppm of propanoic acid, and of 6–90 ppm of n-decanoic acid in aqueous solutions was studied at 308 ± 2 K, by a high pressure mercury arc lamp with variable. polychromatic, radiant power. in the absorption range of semiconductor, between 0.10 and 4.36 W.cm−1 , using PHOTOPERM® CPP/313 membranes. concentric with the lamp. The membranes contained immobilized 30±3 wt.% TiO2. and, in parallel runs, 7 wt.% of a synergic mixture of tri(t-butyl)- and tri-(i-propyl) vanadate(V) as photocatalytic promoter. Stoichiometric H2O2 was used or, in some of the runs, O3, at saturation, as oxygen suppliers. Disappearance of total organic carbon (TOC) was followed as a function of time. Quantum yields, θ0, calculated from initial rates. followed an apparently Langmuirian function of initial concentration, by which θ∞ values at “infinite” concentration could be obtained. Both θ0 and θ∞ values were a function of absorbed power per unit length of lamp (and membrane) (W.cm1), given the geometrical configuration of the photoreactor. Limiting θ∞ values at 0.10–0.35 W.cm−1 substantially coincide with those measured at 0.32 W.cm−1 of monochromatic 254 nm radiation in previous work, for the same substrates. The kinetic model, already used successfully in previous studies, to interpret photodegradation curves up to complete mineralization, is further substantiated.

Light intensity models for annular UV disinfection reactors

AbstractThe finite‐length lamp model was compared to the infinite‐length lamp model (or parallel radiation model) for annular reactors, specifically for the purpose of calculating average light intensities. Based upon the specified conditions that both models must apply equal energy to a reactor, such as is expected when the average surface flux of energy is measured by a chemical actinometric method, the results for the average intensity were very similar for the two models. Long lamp length and short reactor radius favored conditions where the finite‐length model predicted a slightly higher average intensity than that calculated using the infinite‐length model.The inactivation of f2 virus was predicted in a completely mixed flow‐through reactor using kinetic data obtained from batch reactions. For the particular flow‐through reactor used, very little difference for the average intensity was calculated using the two intensity models. Indeed, predictions of reaction results using both models yielded results well within the range of experimental error.

Voltage-current relationship for pulsed arc discharges

A theoretical treatment of the electrical behavior of pulsed discharges in gas-filled flashlamps is presented. The theory is based on a simple model of the plasma and a balance of electrical power input and radiation output. It is assumed that the plasma radiates as a greybody with an emissivity that depends on the electron density. The principal result is an analytic expression for the arc voltage as a function of current, with initial voltage, arc length and diameter, and atom density as parameters. The expression describes the entire voltage pulse, including the initial fall, the following minimum and the peak when the current peaks. The predicted voltages substantially agree with measurements, including dependences on lamp length and diameter and initial voltage. The theory is an improvement on the empirical V-I relation commonly used in flashlamp circuit analyses.

Some Problems in the Design of High Output Finorescent Lamps Fart 3 Considerations on Bulb Diameters

Here are discussed the relations detween bulb diameter and luminous efficiency. The following two parameters were kept constant in all caces: argon filled pressure, 2.2mm Hg and the bulb wall temperature, 35°C. The lamps under test are of bulb diameter from 25mm to 53mm. The results are as follows:1. Lumirous efficiency in the positive column is maximum at the bulb diameter of about 41mm for constant positive column input and at the diameter of about 44mm for constant lamp current.2. As regards the overall luminous efficiency of lamps for constant lamp input:(1) Considerations under the condition of constant lamp length show thata. The relations between bulb diameter and luminous efficiency vary according to lamp length and lamp input. When lamp length is short, small diameter lamps are more advantageous.b. For the initial luminous efficiency the most effective bulb diameter is smaller than 38mm, but for the mean luminous efficiency during lamp life, the lamps of bulb diameter larger than 38mm become more of f icient excepting the case of short lamp length and low lamp input.(2) Considerations under the condition of constant lamp voltage show that the most efficient bulb diameter is larger than than 38mm for both initial and mean luminous efficiency and especially as for the mean luminous efficiency when lamp input is high the lamps of about 45 to 48mm diameter show much betetr efficiency than ones of 38mm diameter.

On the Voltage Allotments in Hot-Cathode Fluorescent-Lamp Circuits

It plays an important roll in the selection of fluorescent-lamps and their series ballasts to determine the voltage allotments in the hot-cathode fluorescent-lamp circuits. Problems are confined to the conventional low power factor lamp circuits, inductive ballasts in series. Lamps having several different arc gap lengths and outer diameters, and ballasts capable to vary their iron core sectional area and number of turns are used for following measurements.The effective values of sinusoidal line voltage, lamp terminal voltage and ballast impedance drop are designated as UN, UL, and UR respectively. Some relations, between these voltages were investigated by R. F. Hays and D. S. Gustin experimentally and H. Stranch theoretically, but these results cannot be applied satisfactorily to many actual cases.Combining several kinds of lamps and ballasts, following results are obtained in the wide range of lamp currents.UL+UR=(1.23±0.03)UN(3)By keeping a lamp current constant and varing the UR/UN values, nearly constant lamp voltage UL is obtained for large UR/UN value, except steep increase at a critical value of UR/UN. From these experiments, the next condition is derived.UR/UN>0.58±0.02(5)In accord with the variation of line voltage UN, the lamp current I varies following the lamp and ballast characteristics. Now the so-called current variation Re is defined by the next equationThe relation between UR/UN values and Re shows that Re increases steeply at a critical value of UR/UN. From these conditions, UL/UN<0.57±0.02(6)can be obtained. When UR/UN<0.66, the lamp terminal voltage wave form has a steep peak-head and the current wave form tends to have some pausal durations. From equation (3) and (6), (7)is obtained. Fquations (3), (6) and (7) are desirable conditions for the lamp life and ballast design.From these relations we can obtain the methods of deciding the lamp length, the design of ballast capacity and many other conclusions.