Thesis (B.M.E.)--Purdue University, 1887. / Manuscript copy.

Thesis (B.M.E.)--Purdue University, 1887. / Manuscript copy.

Thesis (doctoral)--Columbia University. / Vita. Reproduction of original from Harvard Law School Library. Includes bibliographical references.

A comparative study of high intensity DC and AC vortex stabilized arcs operating in argon (at pressures of one to five atmospheres) has been conducted. The energy balance for both the AC and DC arcs has been determined calorimetrically. From these measurements the radiative efficiency (radiation losses/input power) has been calculated. It was found over the current range examined (150-450 amperes) that the radiative efficiency of the AC vortex stabilized arc was comparable to the DC arc. Since DC vortex stabilized arcs have been used as a high intensity radiation source, these results indicate that the AC vortex stabilized arc shows promise for use as a high intensity radiation source. From the energy balance results the heat transfer to the wall was surprisingly found to scale linearly with the radiation losses. The wall loading is not due to absorption of radiation and is much larger than that expected from laminar radial heat transfer. To investigate this further a simple channel model was developed for the luminous DC arc core. From this model the radius and temperature of the luminous arc core was determined as a function of current. The predicted radii were in good agreement with time integrated photographs of the luminous core of the arc. At high current (I>350 amperes) the DC arc radius was essentially constant. The wall heat transfer continued to increase when the arc radius was essentially constant, so that highly efficient heat transfer processes must be taking place outside the central luminous arc core. It is believed that turbulent mixing might be present in this region and be responsible for the large wall heat transfer. The heat transfer processes to the arc electrodes have been measured calorimetrically and the electrode surface temperature has been measured spectroscopically. For both AC and DC electrodes the heat transfer scaled linearly with the arc current. The electrode voltage drop is strongly dependent on gas flow direction with the voltage drop always larger for flow towards the electrode than for flow away from the electrode. These results are not due to convective heat transfer effects. The geometry of the electrode arc attachment region changes when the flow direction is reversed. It is believed that both the anode and cathode fall potentials are altered when the flow direction is reversed, and this is responsible for the difference in electrode voltage drop when the flow direction is reversed. From the electrode surface temperature measurements the heat transfer to the arc electrodes was shown to be essentially one-dimensional in nature. A model of the AC electrode heat transfer was developed using the DC heat transfer results which predicts results for the electrode voltage drop that are in good agreement with the experimental results. The AC electrode heat transfer was found to be <50% of the anode heat transfer in a DC arc at the same current. In the DC arc the anode heat transfer is much larger than the cathode heat transfer. For a practical DC vortex stabilized arc radiation source anode failure is a serious problem, so that the results for the AC electrode heat transfer is of considerable practical importance. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Thesis (Ph. D. in Chemistry)--University of California, Berkeley, October 1958. / Part II of the thesis "high intensity light sources" see UCRL-8509. "UCRL-8508" Includes bibliographical references : p. 98-100.

Thesis (M.S.)--California Polytechnic State University, 2010. / Title from PDF title page; viewed on May 10, 2010. Major professor: Jianbiao Pan, Ph.D. "Presented to the faculty of California Polytechnic State University, San Luis Obispo." "In partial fulfillment of the requirements for the degree [of] Master of Science in Industrial Engineering." "March 2010." Includes bibliographical references (p. 88-93).

A numerical model has been developed for the dynamic simulation of heat and radiation transfer from lamps and ballasts in an enclosure. The model, named LITEAC1, calculates temperatures, cooling loads and illuminances at each simulation time step. LITEAC1 is an improvement upon existing models in the literature in the following aspects: it performs dynamic simulation for all nodes without assuming that some nodes are massless; it calculates illuminances on room surfaces; and it runs faster on a desktop computer. In order to refine the simulation of the two-way interaction between lighting and HVAC systems, a fluorescent lamp positive column discharge model, named LAMPPC, has been incorporated into LITEAC1 to improve calculation of the conversion of input electrical energy into light, thermal radiation and heat. LAMPPC employs established principles in plasma physics to quantify the energy conversion processes.

The objective of this project is to design a facility that will characterize the electrical and optical properties of both tubular and the more recent compact fluorescent tubes. The first stage of this project, which is the subject of this dissertation, was to design, build, test, and model a cylindrical light integrating chamber. An integrating chamber capable of measuring 2-metre long fluorescent tubes was built at the University of KwaZulu-Natal, South Africa. To approximate an infinitely long tube, precisely mounted planar mirrors were placed at opposite ends of the cylinder. The reflectance of diffusive reflective paint and mirrors enter into calculations and were investigated experimentally using a Jarrel-Ash optical spectrometer. The light flux was finally measured for various chamber lengths and compared with a mathematical model. Total light power output from the lamp was calculated and compared with the electrical power input, and the lamp efficiency deduced. Accurate calculations required that the light field surrounding a cylindrical diffuse source be modeled mathematically. The reflection coefficients of the mirrors were not unity and the equations had to be modified to include this effect. The mathematical model was solved using a combination of analytical and numerical techniques. The model results were compared with measurements. The final result includes a mathematical description of the integrating chamber, and a flux-density plot of the space surrounding the fluorescent tube. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2008.

No description available.

Thesis (M.S.)--Humboldt State University, 2009. / Includes bibliographical references (leaves 168-172). Also available via Humboldt Digital Scholar.