换热器的强化传热研究

发布时间：2018-10-31 06:56

【摘要】：节能是发展经济的长远战略,本文主要对换热器强化相关的流动及换热问题进行研究,以期对相关产业的节能降耗有所贡献。首先,通过系列化实验研究提出了一种S型空气预热器以应用于热集成式商业灶具的开发,采用数值模拟和实验验证的手段对其换热性能进行了系统的研究,包括基础数据的测定、结构尺寸的优化、流体流动的分析与传热机理的探究等。从系统经济的角度,以综合利润为目标函数,以换热长度、冷热进口流量和换热面积为设计参数,分析了目标函数与设计参数之间的关系。实验结果表明,采用热集成结构的新型燃气灶具热效率可提高一倍以上。其次,为了进一步优化换热器的换热性能,对涡流发生器的布局和结构进行模拟分析,考察了翅片排布(顺流、逆流)、翼片布局(ABA型、AB型)、翼片尺寸和开孔等对换热效果的影响。通过对比传统涡流发生器(三角翼、矩形翼),提出了一种新型涡流发生器——双三角翼结构。通过模拟优化与实验验证,分析双三角翼涡流发生器的传热机理,并对其结构进行了优化。同时,将传统涡流发生器与新型涡流发生器相结合,论证了复式涡流发生器的优越性。最后,提出将导流结构应用于换热器的强化,设计了一种新型板式换热器。针对液液换热、降膜冷凝和降膜蒸发,对该板式换热器进行了系统的实验研究。对比了不同导流结构对传热的影响,包括竖直波纹板、斜波纹板和开窗波纹板。同时,对比了单层导流结构和双层导流结构对传热性能的强化效果,实验结果表明,采用开窗导流结构能够更好地强化换热。
[Abstract]:Energy saving is a long-term strategy for the development of economy. This paper mainly studies the flow and heat transfer problems related to the enhancement of heat exchangers in order to contribute to the energy saving and consumption reduction of related industries. First of all, a S-type air preheater is proposed for the development of thermal integrated commercial stove by serial experiments. The heat transfer performance is studied systematically by means of numerical simulation and experimental verification. It includes the measurement of basic data, the optimization of structure size, the analysis of fluid flow and the exploration of heat transfer mechanism. From the point of view of system economy, the relationship between the objective function and the design parameters is analyzed by taking the comprehensive profit as the objective function, the heat transfer length, the inlet flow rate and the heat exchange area as the design parameters. The experimental results show that the thermal efficiency of a new type of gas stove with thermal integration structure can be increased by more than twice. Secondly, in order to optimize the heat transfer performance of the heat exchanger, the layout and structure of the vortex generator are simulated and analyzed. The fin arrangement (downstream, countercurrent) and the wing layout (ABA, AB) are investigated. The effect of wing size and opening on heat transfer efficiency. By comparing the traditional eddy current generator (triangle wing, rectangular wing), a new eddy current generator-double delta wing structure is proposed. The heat transfer mechanism of the double delta wing vortex generator is analyzed and its structure is optimized by simulation and experimental verification. At the same time, combining the traditional eddy current generator with the new eddy current generator, the superiority of the duplex vortex generator is demonstrated. Finally, a new type of plate heat exchanger is designed by applying the diversion structure to heat exchanger strengthening. Aiming at liquid-liquid heat transfer, falling film condensation and falling film evaporation, the plate heat exchanger was systematically studied. The effects of different diversion structures on heat transfer are compared, including vertical corrugated plate, oblique corrugated plate and windowed corrugated plate. At the same time, the enhancement effect of single-layer structure and double-layer structure on heat transfer performance is compared. The experimental results show that the use of windowed diversion structure can enhance heat transfer better.
【学位授予单位】：天津大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TQ051.5

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