Theoretical and experimental investigation of an hid lamp

Abstract

Summary form only given. High intensity discharge (HID) lamps of operating pressure ranging from a few atmospheres to a few tens of atmospheres are in wide applications today; from general lighting to high-tech industries. Since the last 4-5 decades, investigations on high pressure discharge lamps have been progressed significantly. In particular, theoretical studies have gotten special attention due to the apparent advantages of low cost and physical interpretability. This work is devoted to study an HID lamp, which is produced purposely for using in theoretical and experimental investigations. The direct current (DC) operated lamp is burnt horizontally having an operating pressure of about 2.5 MPa in a mixture of Hg and Ar. The inter-electrode gap of the lamp is 2.5 mm. Current of the 150-W lamp is maintained at 3.5 A. The ultimate aim is to develop a model for predicting the properties of the whole lamp, to perform experiment for measuring temperature of different sections, and to compare the temperatures of different sections obtained from the numerical calculation and the experimental measurement. In this work, we focus particularly on the electrode temperatures that are of primary importance. The 3-D model solves the electrodes, discharge region and glass-bulb as a single entity. In the fluid or discharge region, the model solves the complete set of magnetohydrodynamic (MHD) equations that comprise the transport equations of mass, momentum and energy along with the Maxwell's equations. In the solid region (electrodes and glass-bulb), the model solves the energy balance equation. The basic feature of the model for the fluid region is the same as reported by Paul et al. with the exception that the current work uses discrete ordinates (DO) method for radiation transport and that it is an integrated solution of the whole lamp. Like other works, the near-cathode or sheath is accounted for in 1-D approach. Temperature measurements of the electrodes are performed for the same lamp and operating conditions using pyrometer. Comparison of theoretical and experimental results is seen in good agreement