{"id":20839,"date":"2019-01-20T09:40:32","date_gmt":"2019-01-20T09:40:32","guid":{"rendered":"http:\/\/sitepourvtc.com\/?page_id=20839"},"modified":"2023-02-17T12:57:07","modified_gmt":"2023-02-17T12:57:07","slug":"nucleate-boiling","status":"publish","type":"page","link":"https:\/\/sitepourvtc.com\/nuclear-engineering\/heat-transfer\/boiling-and-condensation\/nucleate-boiling\/","title":{"rendered":"Nucleate Boiling"},"content":{"rendered":"
Nucleate boiling significantly improves<\/strong>\u00a0the ability of a surface to transfer\u00a0thermal energy<\/a> to the bulk fluid.<\/p>\n The\u00a0nucleate boiling heat flux<\/strong> cannot be increased indefinitely. At some value, we call it the \u201ccritical heat flux<\/strong>\u201d, the steam produced can form an insulating layer over the surface, which in turn deteriorates the heat transfer coefficient.<\/div><\/div>\n The most common type of local boiling encountered in nuclear facilities is nucleate boiling<\/strong>. But in the case of nuclear reactors, nucleate boiling<\/strong> occurs at significant flow rates through the reactor. In nucleate boiling<\/strong>, steam bubbles form at the heat transfer surface and then break away and are carried into the mainstream of the fluid. Such movement enhances heat transfer because the heat generated at the surface is carried directly into the fluid stream. Once in the main fluid stream, the bubbles collapse because the bulk temperature of the fluid is not as high as the heat transfer surface temperature where the bubbles were created.<\/p>\n <\/a>As was written, nucleate boiling<\/strong> at the surface effectively disrupts this stagnant layer. Therefore, nucleate boiling significantly improves<\/strong>\u00a0the ability of a surface to transfer thermal energy<\/a> to the bulk fluid. This heat transfer process is sometimes desirable because the energy created at the heat transfer surface is quickly and efficiently \u201ccarried\u201d away.<\/p>\n Close to the wall, the situation is complex for several mechanisms increase the heat flux above that for pure conduction<\/a> through the liquid.<\/p>\n