蜂窝陶瓷蓄热体的研究现状

综述了高温空气燃烧系统的关键部件之一——蜂窝陶瓷蓄热体的主要发展历程,制备要求以及国内外对蜂窝陶瓷蓄热体热工性能的实验研究和数值模拟现状。可以看出,深入研究蜂窝陶瓷蓄热体的特性对我国发展和应用蓄热式高温空气燃烧技术具有重要意义。     

蜂窝陶瓷蓄热体的热应力研究

建立蜂窝陶瓷的正六边形单通道数学模型,利用CFX流体计算软件,对蜂窝陶瓷在蓄热和放热时的温度分布规律进行了研究,并将数值计算结果与实验结果进行了对比分析,来验证仿真计算结果的可信性。计算分析了不同入口速度以及相同入口条件下不同时刻蜂窝陶瓷的热应力分布情况,结果表明,蓄热体的入口速度越大,应力越大;相同入口条件下,拉应力在蓄热体两端较大,中间较小。     

陶瓷蓄热体的研究现状及应用

陶瓷蓄热体作为陶瓷蓄热技术中的关键部件，它的性能决定了余热回收体系的整体性能。着重对蜂窝陶瓷蓄热体在制备及使用过程中存在的主要问题及解决措施进行了较详细的论述。同时对新型的潜热型复合相变蓄热体的研究现状及发展趋势进行了简单论述。     

蜂窝陶瓷蓄热材料的研究现状

蜂窝陶瓷蓄热材料应该具有热膨胀系数低、比热容大、比表面积大、导热性能好、抗热震性好等特性。本文详细介绍了几种多孔陶瓷材料的优缺点,指出堇青石质复相材料是目前研究最广泛的蜂窝陶瓷材料。堇青石与多种催化剂匹配性好,比表面积大、热膨胀系数小,但耐热性稍差,于是通过添加一些添加剂来提高堇青石作为蜂窝陶瓷蓄热体的性能。这些添加剂与堇青石结合形成复相材料,可以降低热膨胀系数、提高抗热震性等。     

蜂窝陶瓷蓄热体中的辐射传热

蜂窝陶瓷是由贯穿本体非常密集的小孔构成,当载热气体沿孔隙通过蜂窝体时,则其中每一单孔可看作非等温空腔。在前期模型的基础上,以圆形孔道的辐射蜂窝体为研究对象,建立了考虑辐射、对流与热传导复合传热时的能量控制方程。使用FlexPDE软件数值计算出蓄热陶瓷氧化床的温度分布以及辐射对氧化床温度的影响。结果表明,氧化床轴向温度呈梯形分布;辐射具有平滑氧化床温度梯度的作用。所得模拟结果与实验结果较为吻合。     

某钢厂蓄热蜂窝体损坏原因分析

蜂窝蓄热体是高温空气燃烧系统的核心部分,广泛用于冶金机械行业(化工厂、钢铁厂、垃圾焚烧炉、火电厂等)节能技术方面,使回收烟气余热与高效燃烧及降低NOx排放等技术有机的结合起来,从而实现极限节能降低NOx排放量目的。但蜂窝蓄热体在使用中经常产生堵塞、侵蚀及烧损等问题,极大地影响燃烧系统的性能。本文详细分析了某钢厂加热炉蜂窝蓄热体损坏的原因,并提出改进和解决措施,以期为新型、高效、长寿蓄热体及其安装等提供参考。     

加热炉蓄热式燃烧技术用蜂窝体的研究与应用

蓄热式高温空气燃烧技术（HTAC）是新一代高效节能、环保技术，而其中的蓄热式蜂窝体是该项技术的关键。本文介绍了首钢中厚板轧钢厂2号加热炉蓄热式改造用蜂窝体的材料、性能及其传热、阻力性能研究和实际应用情况。     

蓄热式氧化器用陶瓷蓄热体性能测试及对比

介绍了蓄热式热氧化器(RTO)主要使用的几种陶瓷蓄热体,并模拟RTO设备的运行,测试几种蓄热体的性能,对RTO设备的设计具有指导意义。     

工业窑炉蓄热式换热器用莫来石质蜂窝陶瓷的研制

以高铝矾土、粘土、莫来石为主要原料 ,添加适量硅线石、红柱石和蓝晶石 ,用挤出成型法制备了蜂窝陶瓷。利用TG -DTA分析了在烧成过程中所发生的物理化学变化 ;X射线衍射分析结果表明 ,材料的主晶相为莫来石。     

蜂窝型蓄热体传热过程热工特性的数值研究

介绍了高温空气燃烧过程中蜂窝型蓄热体的工作原理和损毁原因 ,并建立蓄热体三维非稳态传热数学模型。采用代数雷诺应力模型和修正的速度 -压力耦合算法SIMPLEC ,耦合蓄热体内流体的流动和换热过程 ,用数值计算的方法研究了蜂窝型蓄热体的传热特性和格孔壁面上的应力变化规律。结果表明 :适当降低流过蓄热体的气体流速 ,缩短四通换向阀的切换时间 ,可降低烟气的出口温度 ,提高系统的余热回收率。频繁的蓄热和释热过程变换 ,使蓄热体格孔壁面交替受到拉应力和挤压应力的作用 ,换向时间越短 ,应力交替作用的影响越大 ;流体的流速越大 ,应力变化越大     

降低蜂窝状堇青石陶瓷载体热膨胀的途径

详细叙述了降低蜂窝状堇青石陶瓷载体热膨胀的各种途径。主要包括设计适宜的化学组成 ,控制各种原料的种类、杂质含量、形貌、粒度以及对其进行必要的预处理 ,选用合适的添加剂 ,选择最佳烧成工艺 ,调节气孔率、孔径分布和烧成后陶瓷体的酸处理。     

膜反转板式降膜再生器的性能

膜反转板式降膜再生器是一种结合板式降膜与膜反转技术的新再生器型式。掌握其性能对今后的工业应用十分重要。本文以一个膜反转板式降膜再生器与板式降膜再生器作为比较。在相同设计条件下设计获得两个不同型式的再生器，通过对数学模型的求解，进行了不同发生压力、溶液流量、进口浓度、进口温度及加热条件下两者传热传质性能的计算与比较。结果表明在不同工况条件下，两者性能变化有所不同。由此，在膜反转板式降膜再生器替代板式降膜再生器的应用中应当考虑它们变工况性能的差异。     

扩缩方孔蜂窝蓄热体强化传热的数值模拟

为提高烟气余热回收率,提出一种扩缩方孔蜂窝蓄热体,通过用户自定义函数(UDF)实现烟气和空气周期切换时流体种类和进口速度、温度等参数的改变,基于ANSYS Fluent软件建立了新型蓄热体的三维非稳态传热数值模型。通过比较模型预测值与文献实验值进行了模型验证。利用模型研究了新型蓄热体方孔扩缩角、扩缩节距和总长度对其传热和流阻性能的影响。通过温度云图分析了扩缩通道强化蓄热体性能的机理。结果表明,缩放通道能有效提高蜂窝蓄热体的传热性能,在压力损失增加不多的前提下,蓄热体效能最多提高约5个百分点。扩缩方孔蜂窝蓄热体长度越长,其传热性能越好;对于一定长度的新型蓄热体,扩缩节距(或扩缩角)不变时,蓄热体传热性能随扩缩角(或节距)增大而增强。扩缩角过大时,新型蓄热体流动阻力很大,综合性能不佳。     

Fabrication and characterization of honeycomb β-tricalcium phosphate scaffolds through an extrusion technique

In this study, for the first time honeycomb β-tricalcium phosphate (β-TCP) scaffolds were fabricated through an extrusion technique. The physicochemical properties and cell behaviors of the honeycomb β-TCP scaffolds were investigated. The results showed that scaffolds were characterized by ordered channel-like macropores and unidirectional interconnection. The pore structure and mechanical strength could be tailored by changing the parameters of extrusion molds. The pore size of scaffolds was in the range of 400–800 µm approximately, while their compressive strength parallel to the pore direction and porosity ranged from 14 to 20 MPa and 60–70%, respectively. The in vitro cell behavior demonstrated that cells could well attach on the surfaces and grow into the inner channel-like pores of thescaffolds; the scaffolds with higher porosity showed better cell proliferation but poorer cell differentiation. The honeycomb scaffolds fabricated by extrusion technique are potential candidate for bone tissue engineering.     

High strength and microwave-absorbing polymer-derived SiCN honeycomb ceramic prepared by 3D printing

The combination of 3D printing technology and polymer-derived ceramic route provides an attractive strategy to construct microwave-absorbing honeycomb with fine structure through flexible process. However, preparation of honeycomb ceramics with both excellent mechanical and microwave-absorbing properties is still challenging. Herein, SiCN honeycomb ceramic was fabricated by stereolithography from UV curable polymeric precursor consisting of polysilazane and multifunctional acrylates. By optimizing the multifunctional acrylates and its ratio, the decomposition of organic moiety and the ceramization process of precursor are matched, rendering the achieved ceramic with high compactness. The hardness and specific compressive strength of SiCN honeycomb ceramic reach as high as 14.3 GPa and 333.3 MPa/(g·cm³), respectively. Meanwhile, at low pyrolysis temperature, the copolymerized acrylate and polysilazane that formed during curing process was converted to free-carbon nanodamins in-situ, which endows SiCN honeycomb ceramic with the minimum reflection loss of –49.0 dB, namely microwave absorption rate over 99.99%.     

Promotion of the alginate gelling method for preparing Al2O3 honeycomb ceramics

In this work, Al₂O₃ honeycomb ceramics with unidirectionally aligned channels were fabricated by the ionotropic gelation process of alginate/Al₂O₃ suspensions. By heating the bottom of the suspension container during the gelation step, the heat energy conducted upward from foot to the top surface of the slurry, which has shortened the gelation time from 48 to 10?h and improved efficiency dramatically. Meanwhile, as the heating temperature increased from 25 to 40°C, the porosity of Al₂O₃ honeycomb ceramics remained unchangeable with the pore size decreasing from 163 to 79?μm for the increasing opportunities for forming capillaries in the primary membrane. By the integrated effect of unidirectional pore channels and dense pore walls, both the compressive strength and water permeability of the sintered samples were higher than those of Al₂O₃ foam ceramics.