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Show The Brigham 'Young University (BYU) atmospheric combustor is a coal-fired, axisymmetric laboratory furnace. It is a 20 em diameter furnace that is 1.5 m tall and fired from the top with a single swirled burner (swirl no. = 2.0). In the case studied, 14 kg/hr of a Utah su bbituminous coal was fired at a st.oichiometry Dear 1.0. The coal grind was that of a typical power plant with a mass mean diameter of 49 pm. The steel outer shell of the reactor is lined with about 10 cm of castable ceramic and inside wall temperatures are monitored . Local samples are collected with watercooled, ,vater-quenched sample probes at various axial and radial sampling stations. The well characterized conditions and local samples al10w this furnace to he used to study more detailed phenomena than can be accurately measured on a larger scale. Heterogeneous and turbulent heat transfer aspects strongly influence the performance of practical pulverized coal combustion systems since many of the su bprocesses within the flame are highly temperature sensitive, and since the purpose of most furnaces is to extract ~nerg) from the flame. Historically, heat transfer studies in flames have focused on radiative transfer to water walls, boiler tubes and other surfaces, since the amount of extractable energy is usually the variable of major interest for furnace operation. However, it is recognized that performance of the pc flame itself is dependent on many coupled phenomena such as devolatilization, heterogeneous oxidation. and turbulent gas and particle mixing which drive the overall heat transfer to the heat exchange surfaces and yet are controlled by the local heat transfer within the system. Although n10st of these local heat transfer processes are well studied individually~ their combined effects and their coupling to the other physical and chemical processes within the flame are more difficult to quantify or measure than simple wall heat fluxes ; thus, their inlpact is less documented . Coal combustion simulation or computer modeling perrruts in\'estigation of the effect of various heat transfer mechanisms with pc flames on the many other simultaneous processes of turbulent fluid mechanics, coal conversion, gaseous reaction, etc. A numerical simulation of the coal furnace allows the well studied fields of convective/ conductive heat transfer to particles, particle-laden radiative heat transfer and turbulent convection to be coupled with the other physico-chemical processes occurring in coal combustion in order to study the combined impact of these local and global processes on the furnace performance. Alth ough all of these subprocesses have been well studied, there remains a significant ]evel of uncertainty in our knowledge about each of then1 . Numerical simulatioL bas produced some justifiable skepticism on the part of son1e scientists on the accuracy of overall predictions because of the combined uncert.ainty fronl the many ~u bprocesses needed to comprehensively calculate furnace performance. Oyer the pa5t ten years we have spent a significant effort in evaluat.ing the capability of 8 |