| 摘要 |
A liquid, in heat transfer contact with a surface heated to a temperature well above the vaporization temperature of the liquid, will undergo a multiphase (liquid-vapor) transformation from 0% vapor to 100% vapor. During this transition, the temperature driving force or heat flux and the coefficients of heat transfer across the fluid-solid interface, and the vapor percentage influence the type of heating of the fluid-starting as "feedwater" heating where no vapors are present, progressing to "nucleate" heating where vaporization begins and some vapors are present, and concluding with "film" heating where only vapors are present. Unstable heating between nucleate and film heating can occur, accompanied by possibly large and rapid temperature shifts in the structures. This invention provides for injecting into the region of potential unstable heating and proximate the heated surface superheated vapors in sufficient quantities operable to rapidly increase the vapor percentage of the multiphase mixture by perhaps 10-30% and thereby effectively shift the multiphase mixture beyond the unstable heating region and up to the stable film heating region.
|
