有机热载体炉中热载体流速的最佳选择

采用最优化算法选择了有机热载体炉中的热载体在安全运行条件下的经济流速，讨论了一些因素对最佳流速的影响。文中采用的方法及计算数据可供设计与运行同型热载体炉时参考。本文的优化计算方法也可用于管式加热炉的优化设计。     

液相有机热载体炉安全阀的探讨

对液相有机热载体炉及系统中安全阀的安装及计算方法作介绍。     

有机热载体炉技术及其进展

文章在分析有机热载体特点和结构设计的基础上讨论了有机热载体炉的技术及其进展。指出：高能效、低排放技术,先进的设计技术,精确的制造技术,在线过滤、监测、分析、清洗技术等运行控制技术是有机热载体炉未来发展方向。     

有机热载体炉内导热油结焦及其预防研究现状

综述了导热油的种类、结焦机理、结焦过程的影响因素及预防措施。研究指出,温度、流速和管路表面处理是导热油结焦的主要影响因素,进而提出多项预防措施。这些研究成果对提高有机热载体炉的运行效率和安全性至关重要。     

论有机热载体炉的应用技术及节能

有机热载体炉是国家“八五”重大科技成果推广项目．有机热载体炉又称“导热油炉”是一种以煤（油、气）为燃料以导热油为热载体，利用循环泵强制波相循环，将热能输送给用热设备后，继而返回重新加热的直流式特种工业炉（见附图）．这种特种工业炉目前越来越多地应用于化工、轻工、纺织、印染、塑料、橡胶、粮食加工、木材、公路建筑等工业领域的加热热源，其出口温度可达340℃，且可自动调节温度。有机热资体炉在江苏生产使用较多，发展也较快，节能效果非常明显，一般在3～8个月就可收回投资成本，但目前，很多用热设备的用户只知道用工…     

Couette flow through a porous medium of a high prandtl number fluid with temperature-dependent viscosity

The velocity and temperature profiles for an impulsively started Couette flow have been derived for a fluid with a high and strongly temperature-dependent viscosity when the flow takes place through a porous medium. The steady as well as the transient state flows are discussed and the influence of the medium permeability is assessed. In the steady state the presence of the porous medium causes higher maximum temperatures only for sufficiently low permeabilities and in all cases significantly lower velocity profiles. The flow development times tend to be higher for the low permeabilities only for high Nahme numbers. For the transient state it is noticeable that, in all cases, the velocity develops much more rapidly than the temperature and that the presence of the porous medium accelerates this tendency. Finally the medium permeability produces skew temperature profiles and higher temperature time gradients at all times.     

锅炉改造影响热效率的因素分析

介绍了ＬＳＦ０．３－０．０９型锅炉的改造过程、结构特点,以及锅炉改造过程中出现的主要问题及改进措施。     

一则有机热载体锅炉检测案例

锅炉作为常用的压力容器使用已非常广泛,目前常用的锅炉传热介质有水和有机热载体。本文分析了有机热载体和水介质之间区别以及对锅炉生产的影响。并对有机热载体的主要检测指标进行了分析,介绍其对锅炉使用的影响以及有机热载体锅炉的主要劣化表现。最后通过案例分析了一起由于混合用油导致的酸值和残碳值的增加,分析了两个值增加的原因,并分析了锅炉介质不进行处理容易产生的安全隐患。     

一种新型集热介质热工性能的试验与分析

通过实验测定了一种新型集热介质的凝固温度、膨胀系数、比热容及传热系数等性能参数,并与水进行了比较。结果表明,该介质无腐蚀性,在零下40℃不会凝固结冰,其比热容小于水,升温快,传热性能好,在对数温差较小时传热系数大于水,因此可用作太阳能集热器的循环介质,应用于太阳能建筑一体化采暖、热水供应系统,能够保证系统在冬季正常运行,不会冻结且节能高效。     

有机热载体锅炉尾部高效余热利用装置的设计与应用

有机热载体锅炉广泛应用于纺织、印染行业,由于高温定型和染整的特殊工艺以及有机热载体锅炉的构造和运行原理造成其尾部排烟温度在300℃左右,产生巨大的热能浪费。为减少热能损失,通过高温烟气的余热回收利用,提高有机热载体锅炉的综合热效率,可实现节能降耗和减排。本课题运用热管技术设计研制了结构合理、操作方便、高效的有机热载体锅炉尾部高温烟气的回收再利用装置。     

直接膨胀式太阳能热泵系统的理论分析

简述了直接膨胀式太阳能热泵的基本工作原理,从热力学理论出发,对直接膨胀式太阳能热泵的循环进行了理论热力分析,提出了系统各主要部件的能量平衡和火用平衡方程,分析了系统的性能系数COP和火用效率Eη。     

Unsteady mass transfer in mixed convective heat flow from a vertical plate embedded in a liquid-saturated porous medium with melting effect

This paper numerically studies the transient mass transfer in mixed convective heat flow with melting effect from a vertical plate in a liquid saturated porous medium in the presence of aiding external flow. The governing equations are transformed into the non-dimensional form by using pseudo similarity coordinate (ζ) and dimensionless time (ξ). The resulting two dimensional boundary value problem (BVP) is then solved by the method of lines (MOLs) with the central finite difference and Newton's iteration to obtain the entire numerical solutions for all transient process from the initial stage (ξ = 0) to the final state (ξ = 1). The results show the rate of dynamic mass transfer at the solid–liquid interface is reduced with increasing the melting strength. In addition, the response time and the rate of the dynamic mass transfer for aiding buoyancy are respectively shorter and faster than those for opposing buoyancy from the transient molecular diffusion to the steady mixed convection in a porous medium with melting effect.     

Experimental study on the effect of porous medium on performance of a single tube heat exchanger: A CO2 case study

An experimental study on single‐phase laminar forced convection in a single porous tube heat exchanger is presented. Parametric studies are conducted for different inlet pressures, different mass flow rates, and different porosities to evaluate the effects of particle diameter and Reynolds number on the heat transfer and friction factor. The Nusselt number and friction factor are developed for efficient design of a porous heat exchanger based on the present configuration. Heat is transferred to the walls of the heat exchanger by natural convection mode. Gravel sand with different porosities is used as a porous medium during the tests. The flow of carbon dioxide as a working fluid in the porous medium is modeled using the Brinkman–Forchheimer‐extended Darcy model. A dimensionless performance parameter is developed in order to be used in evaluating the porous tube heat exchanger based on both the heat transfer enhancement and the associated pressure drop. The study covers a wide range of inlet pressures (P_i), mass flow rates ( ), porosity of gravel sand (ε), and particle diameters (d_m) which ranged 34.5 ≤ P_i ≤ 43 bars, 8 ?? 10^?5 ≤ ≤ 16 ?? 10^?5 kg/s, 34.9% ≤ ε ≤ 44.5%, 1.25 ≤ d_m ≤ 5.15 mm, respectively. This study revealed that a smaller particle diameter can be used to achieve higher heat transfer enhancement, but a larger particle diameter leads to a more efficient performance based on heat transfer enhancement. The average heat transfer coefficient of carbon dioxide decreases when the porosity increases. © 2013 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com/journal/htj). DOI 10.1002/htj.21059     

低Re下板式换热器性能的实验研究及热力学分析

实验测定了两种不同板式换热器在低Re条件下(200相似文献   

The interaction between internal heat loss and external heat loss on the extinction of stretched spray flames with nonunity Lewis number

The influences of flow stretch, preferential diffusion, internal heat transfer and external heat loss on the extinction of dilute spray flames propagating in a stagnation-point flow are analyzed using activation energy asymptotics. A completely prevaporized mode and a partially prevaporized mode of flame propagation are identified. The internal heat transfer, associated with the liquid fuel loading and the initial droplet size of the spray, provides heat loss for rich sprays but heat gain for lean sprays. The flow stretch respectively weakens and intensifies the burning intensity of the lean methanol-spray flame (Le>1) and rich methanol-spray flame (Le<1). Results show that the Le>1 flame can be extinguished with or without external heat loss. Flame extinction characterized by a C-shaped curve is dominated by the external heat loss or the flow stretch. For the Le<1 flame without external heat loss, no extinction occurs under the influence of flow stretch. However, the Le<1 flame with completely prevaporized fuel sprays enduring a small amount of flow stretch can be extinguished by the external heat loss and this behavior is characterized by a C-shaped curve. Note that the W-shaped extinction curve is mainly governed by the internal heat loss. Flame extinction characterized by a W-shaped curve occurs when the Le<1 spray flame with external heat loss endures a positive stretch and experiences a partially prevaporized spray with sufficiently large liquid fuel loading and droplet size.