Foreign body in the tracheobronchial tree is serious and, on occasion, fatal. The symptoms and signs can be confused with asthma and pneumonia, leaving the true condition unsuspected. Children one to three years old with a triad of cough, wheezing and decreased air entry should be suspected. A child with protracted pneumonia should be reconsidered. Chest films in the expiratory phase should be taken. In no other operative procedure is it more important to have teamwork and good communication between endoscopist and anesthesiologist, when the diagnosis is made.

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SUMMARYRecently, molten salt has received attention as a promising coolant for advanced nuclear reactors, especially for fluoride salt-cooled high-temperature reactor. The heat transfer characteristics of molten salt provide great advantages for application as a primary coolant, because of its superior performance in terms of sustainability, economics, safety, and reliability compared with gas coolant. However, understanding the thermal-hydraulic characteristics of molten salts by experimental method is difficult because of its high-temperature corrosion and toxicity issue. Therefore, oil fluids were introduced as simulants for studying the heat transfer phenomena of high Pr (Prandtl number) molten salts. In this study, a scaleddown experiment using simulant oil was conducted, and scaling laws were applied to investigate a single-phase natural circulation, which is important in nuclear reactors as a part of their passive safety. DOWTHERM RP (Diaryl Alkyl) was considered as a heat transfer simulant in this study because it matches the relevant dimensionless numbers (Prandtl number, Ra, Grashof number, Reynolds number, etc.) with those of molten salt. Prior to the experiment, the thermophysical properties of both the liquid and vapor phases of DOWTHERM oils were implemented into thermal-hydraulic system analysis code or multi-dimensional analysis of reactor safety code, to enable simulation and further study of the molten salts. Then, natural circulation experiments were conducted with the scaled rectangular loop, to establish similarity and experimental feasibility. For the validation, two different codes (multi-dimensional analysis of reactor safety and computational fluid dynamics (CFD) were used to simulate the same natural circulation loop. From the experimental data, new heat transfer correlation for a single-phase natural convection was developed, and the existing heat transfer correlations were compared. Copyright

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