换热强化及其优化设计的新途径

审视了强化换热及其优化设计换热系统的方法,无论是传统的强化换热方法还是场协同方法,都只片面地强调了强化传递强度而忽视了由于强化所引起的能量耗散的约束。在强化传递强度的层次上,给出了换热强度与流体中内场和外场的数学关系,通过协调不同驱动力之间的关系可以强化热传递强度。在优化设计换热系统的层次上,给出了优化设计的热力学判据,表明了不可逆性与推动力之间的权衡,并由此得到换热器强化的优化设计温差。

New approach to heat transfer enhancement and optimum design of heat transfer systems

The approaches to heat transfer enhancement, whether they are traditional or field-synergic, only emphasize the intensity of heat transfer unilaterally, and ignore the restriction of energy destruction caused by heat transfer enhancement. On the levels of intensity of enhancing heat transfer, a mathematical relationship between the intensity of heat transfer and the internal field as well as external field in the fluids is given, which shows that the intensity of heattransfer can be controlled by adjustingthe relationship between differentkinds of driving forces. On the levels of optimum design of heat transfer systems, a thermodynamic criterion for optimum design of heat transfer units is proposed, which indicates the trade-off between irreversibility and driving forces. Further the optimum temperature difference for design of heat exchanger is obtained.