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Show - 5 - In this study, the physical structure of several flames and their relative flame speeds are used to characterize the capability of the system to minimize total emissions. To do so, avoidance of heat and radical loss to the burner and other surfaces is critical. Previous premixed flame studies of trichloroethylene have used flat-flame burners [14,15,16] as well as Bunsen burners [13]. Hat-flame burners require stabilization devices downstream and result in flames close to the burner which cause excessive heat and radical losses [14,15,16]. In this study a Bunsen-burner type flame was used to avoid these complications. Experimental Methods A Bunsen burner type flame was selected (as explained above) to minimize heat and radical loss effects. The burner system consisted of a 2.5 em inner diameter stainless-steel tube which contracted to a 1.27 em inner diameter exit nozzle. TIle burner was designed to achieve fully developed flow prior to the contraction section. The mixing plenum of the burner was supplied with gas metered through Edwards mass-flow controllers. Gases included ethylene (99.95% purity, AIRCO), chlorine (99.96% purity, AIRCO), oxygen (99.993% purity, AIRCO) , nitrogen (99.999% purity, AIRCO), and air (dry, less than 1 ppm THC, AIRCO). Liquid fuels were gasified in a stainless-steel thennostated evaporator which allowed stable flow conditions over long operating times. Liquid fuels included hexane (Fisher Scientific) and trichloroethelyene (Fisher Scientific). Co-flowing air with a unifonn velocity distribution shrouded the flame. TIle liquid as well as gaseous flows were heated and thennostated. All experiments were operated under constant average exit nozzle velocity (45 cm/s). This allowed a simple comparison of flame speeds between different experiments by simple observation of flame shapes and positions. A detailed analysis of flame shapes and positions was obtained using a Panasonic ceo array camera with a Data Translation frame-grabber and data processing board in conjunction to a microprocessor. In addition, still photography was employed using a SLR camera with a macro-zoom lens. |