Analysis Of Convective Heat Transfer Enhancement Using The Principle Of Least Action

Convective heat transfer enhancement technology is widely used in various industry departments of national economy, which can save energy, reduce the cost and it's the key technology to promote and adapt to high heat current.Its fundamental task is to design and control the heat transfer process. As a typical irreversible process, the enhancement target of convection heat transfer process can be attributed to the process of decreasing irreversiblilty. Entropy production and entransy dissipation are two qualities used in characterizing irreversiblilty of convection heat transfer process. The heat transfer enhancement study includes finding ways to reduce the entropy production or entransy dissipation. The former is called thermodynamic optimization, the latter the heat transfer optimization.In order to establish a systematic theory of heat transfer technology, the least action principle and field synergy principle was introduced in the study of heat transfer. Field synergy principle explains the physical mechanism of various types of heat transfer from the uniform point of flow and temperature fields, getting a lot of useful conclusions, but the theory failed to point out specific ways to carry out the optimal flow field. In this thesis, from the least action principle and field synergy aspects , we analyze the mechanism of heat transfer enhancement of the rod baffle and swirl plate and hollow ring. Field synergy principle is concerned about the heat transfer but the influence of the flow resistance.Of heat transfer principle of least action, the minimum entropy production principle and the principle of entransy dissipation extrimum are of widespread concern. Particularly, the functional optimization model and its variational principle based on the concept of entransy dissipation are considered to be the most optimized principle to guide the heat transfer reinforments. Functional optimization model and stationary conditions of variation are attributed to the field synergy equations, the equations are considered to be the best description of the convective heat flow control equations. For the current optimization model and its functional variational principle, this paper uses theoretical analysis and numerical simulations to solve a detailed comprehensive comparison and analysis from its physical meaning of functional model, the establishment of channels and methods, finding these variational principles are only established under specific strict conditions. Meanwhile, the field synergy equations are not complete variational stationary conditions, solution methods are also approximate, it can not conclude that the result is the most optimal solution. For the current convective heat transfer enhancement , the principle of least action and its functional optimiztion model still need to be further improved.