共查询到17条相似文献,搜索用时 859 毫秒
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在炉膛压力变化情况下,对增压锅炉相关热力计算参数的变化规律进行了系统地分析,并针对某型增压锅炉进行了实例计算,得出了其烟气流速及炉膛黑度随压力的变化曲线。增压锅炉炉膛压力升高时,其容积热负荷和炉膛黑度将增大,炉膛出口烟温及线性流速等将减小,而烟气的对流换热系数等参数不变。 相似文献
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中心回燃式锅炉自引进以来一直没有一种理想的燃烧室传热计算方法,本文根据中心回燃式锅炉燃烧室内射流火焰与回流烟气之间存在着强烈的掺混,认为燃烧室传热计算中不应忽略对流换热。提出了适合中心回燃式锅炉燃烧室传热的计算方法,并通过实验加以验证。 相似文献
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由于增压锅炉燃烧压力的提高,强化了对流传热,如果仍按常压燃烧锅炉炉膛热力计算,忽略对流传热,将直接影响增压锅炉炉膛热力计算的准确性。文中对增压锅炉与常压燃烧锅炉炉膛特性参数进行了比较,对前苏联增压锅炉的试验数据进行了分析探讨,指出了增压锅炉炉膛对流传热的影响因素。同时提出增压锅炉炉膛传热计算应将辐射与对流传热分开计算,给出了适用于增压锅炉炉膛对流传热的计算公式,并进行了实例计算分析,与前苏联增压锅炉试验的计算数据结果相近。对于完善增压锅炉的炉膛热力计算具有一定的理论和实际指导意义。 相似文献
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Results of an investigation into the sensitivity of natural convection heat transfer correlations with respect to relative humidity are presented. Given the relatively small values of natural convection heat transfer coefficients, small changes in the thermophysical properties can have a significant impact on the values predicted by theoretical/empirical correlations. In this study, the thermophysical properties are assumed to be those of a dry air and water vapor mixture. The mole fractions are determined as a function of relative humidity. Several widely used natural convection heat transfer correlations have been examined to determine the impact of varying the relative humidity on the predicted Nusselt number. The results show a general trend of an increasing Nusselt number with relative humidity. The results presented in this paper provide an engineering tool for obtaining accurate values of natural convection heat transfer coefficients for a moist air environment using only the thermophysical properties of dry air. 相似文献
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Typically for single component fluids, the variation of thermophysical properties is negligible except in the presence of large temperature differences, and, therefore, has no appreciable effect on the heat transfer. In contradistinction, thermophysical properties can vary significantly due to concentration differences which affect the heat and mass transfer. This work examines the effects of thermophysical property variation on the heat and mass transfer in a cavity due to natural convection driven by combined thermal and solutal buoyancy forces. Results indicate that thermophysical property variations can appreciably influence heat and mass transfer and velocity distribution. 相似文献