PSR波纹板片的热强度分析

提出一种新型紧凑式回热器——一次表面回热器(PSR)的强度设计技术。结合船用ICR燃气轮机一次表面回热器研发，以3．7MW燃气轮机为背景，根据热弹性力学和传热学理论，建立PSR板片热强度分析物理数学模型，并对波纹曲线为椭圆、正弦波和抛物线的3种常见波纹传热板片所受热应力做了对比计算，分析了板片厚度，两侧压差，本身温度及形状对板片热强度的影响。给出基于Von Mise等效应力极值σrmax的板片最小设计厚度δmin，还研究了波纹板片在典型工况下的弹性变形情况。本文工作对PSR的结构设计有重要参考价值：     

一次表面回热器瞬态响应特性的数值分析

基于能量守恒原理,根据一次表面回热器(PSR)的结构、流动特点,导出它的瞬态温度变化物理模型和数学方程式。研究温度和流量发生阶跃变化时PSR的响应特性,还分析了PSR波纹板片的数目n、波纹板片的长度L、宽度W和厚度等各几何参数以及波纹通道的形状对温度响应时间的影响。比较研究表明,由于PSR的固体壁面时间常数远小于板翅式和管壳式换热器。因此,这种轻重结构的换热器响应特性明显优于常规热交换器,非常适用于那些要求机动多变、灵敏反应的舰船燃气轮机或车用内燃机等动力装置。图9表3参12     

板壳式换热器板片流动与传热性能的数值模拟

针对板壳式换热器的人字形板片建立了单流道物理模型,并利用数值模拟软件分析了其重要结构参数波纹夹角的变化引起的模型流场、速度场和温度场的变化情况,以及对其传热性能的影响。结果显示:换热板片波纹夹角的变化使得流体的流动状态发生了变化,随着波纹夹角的增大,流体的流态由十字交叉流逐渐转变为曲折流。随着波纹角度的增大,流体的扰动程度加强,湍流程度提高,与此同时,努塞尔数和传热因子增大,传热性能增强。模拟结果表明波纹夹角对板壳式换热器流动和传热性能具有较大的影响,可以成为板壳式换热器优化设计的一个重要方向。     

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   

波纹板式空气预热器内流动换热过程的数值模拟

对波纹板式空气预热器内换热与流动过程进行数值模拟,分析了波纹板片的结构特征、波纹倾角β、波纹高度H、波纹节距以及板间距对空气预热器性能的影响.结果表明:当波纹倾角和波纹高度增大时,换热性能提高但是压降增大,在β=45°、H=10mm时换热性能最优;波纹间距的改变对换热性能影响较小,但板间距的影响较为明显,综合考虑换热器的紧凑性,选用较小板间距能达到较好的换热效果.     

波纹板换热器板间流动与传热的有限元计算分析

通过有限元法计算了波纹板式换热器板间温度场与速度场分布,情况，对八种板型进行了计算，计算结论通过图示表明不同的波纹板板型的传热与流动性能。     

应用遗传算法优化设计微型燃气轮机原表面换热器

提出将热力性能设计与遗传算法搜索过程相结合的方法.对适用于100 kW微型燃气轮机的人字形交错波纹板式原表面换热器进行结构优化,分别以重量最轻和换热紧凑度/重量最大作为目标函数,把换热器芯体外形尺寸和换热表面结构尺寸作为待寻求最佳值的优化变量进行优化.遗传算法程序采用二进制编码,锦标赛选择,均匀交叉和单点变异,并采用基...     

板管式间接蒸发冷却换热器的设计分析

介绍一种结构具有代表性的间接蒸发冷却换热器——板管式间接蒸发冷却换热器,并从芯体结构、材料的选择、芯体的换热计算和各功能部件的设计计算等方面进行详细设计分析。     

强化凝结与液膜传热过程的板壳式换热器波纹方案

板壳式换热器敝开的板外侧通道可以实现多种板式换热器所不能实现的传热过程，特别是液膜传热伟质过程。针对不同过程的特点设计波纹的波型是板壳式换热器推广应用的关键，文章介绍了适合于凝结过程的同向双尺度波纹板片和适合于吸收，蒸发等液膜传热传质过程的交叉双尺度波纹板片方案。     

热管式空调换气换热器的设计与研究

本文提出了一种以热管为传热元件的全气候使用的空调换气换热器，就其设计特点、结构型式及性能评价和效益分析作了叙述。换热器中的热管采用氨－铝热管，分重力式热管和吸液芯式换管两种。重力式热管空调换气换热器采用了随电机正反转改变进排气方向的轴流式风机；吸液芯式换热器采用了特殊结构设计，解决了吸液芯热管受安装误差带来的热管半失效问题。     

一次表面回热器动态特性的数值模拟与实验研究

对一次表面回热器(Primary Surface Recuperator,PSR)流量阶跃变化时的动态特性进行了数值分析和实验研究.根据能量守恒原理和一次表面回热器(PSR)的结构特点,导出回热器冷热流体和固体间壁非稳态温度变化的微分方程式,研究流体流量发生阶跃变化时PSR的响应时间.在冷热空气进口参数和换热量相同的条件下,当冷热侧流量分别增加为原来3倍的情况下,PSR的响应时间只有管壳式换热器的1/8,板翅式的1/3.数值分析结果与实验结果相符.由于PSR的固体壁面时间常数远小于板翅式和管壳式回热器,因此这种轻重量结构的先进回热器响应特性明显优于常规回热器.     

船用燃气轮机一次表面回热器的设计分析

提出了一种新型紧凑式回热器——一次表面回热器(PSR)的设计技术。结合船用ICR燃气轮机一次表面回热器的研发，简述PSR的结构特点及其设计计算的理论依据，并给出了设计算例。研究表明，一次表面回热器具有极高的紧凑性和卓越的换热性能，因而这种先进的热交换装置必将替代那些常规的热交换器，在船用动力装置及先进热工程设施中发挥重要作用。     

Steady-State and Transient Investigation of the Primary Surface Recuperator for Microturbines

The aim of this work is to study numerically and experimentally the thermal performance of the primary surface recuperator (PSR) operating under steady and transient conditions. Numerical simulations are carried out to investigate the heat transfer characteristics in the corrugated passages of the primary surface recuperator. The effects of velocity, intersection angle, and pitch-to-height ratio are considered. Numerical simulation of the transient behavior of the PSR is performed as its mass flow rate or hot inlet temperature is subject to a sudden change, which is based on the conservation theorem of energy and its structural characteristics. One prototype of a PSR for experimental purposes has been designed and manufactured, and is used in an experimental setup to carry out the experimental studies. The comparative results show that the low-weight PSR has much more advantages in transient response because its time constant of the solid wall is much less than that of a shell-and-tube recuperator or plate-fin recuperator. The PSR is quite fit for application to the marine or vehicle gas turbine engine that works under changeable conditions.     

Theoretical prediction of longitudinal heat conduction effect in cross-corrugated heat exchanger

In the elementary heat exchanger design theory, the longitudinal heat conduction through the heat transfer plate separating hot and cold fluid streams is neglected, and only the transverse heat conduction is taken into account for the conjugate heat transfer problem. In the cross-corrugated heat exchanger, the corrugated primary surface naturally leads to the highly non-uniform convective heat transfer coefficient distribution on opposite sides of the plate. In such a case, the longitudinal heat conduction may play a significant role in the thermal coupling between high heat transfer regions located on opposite sides of the plate. In the present study CFD is used to perform a quantitative assessment of the thermal performance of a cross-corrugated heat exchanger including the longitudinal heat conduction effect for various design options such as different plate thickness and corrugation geometry for a typical operating condition. The longitudinal heat conduction effect is then predicted by the theoretical method using the ‘network-of-resistance’ in the wide range of the heat exchanger design space.     

Thermal design and model analysis of the Swiss-roll recuperator for an innovative micro gas turbine

For the advanced power systems based on the use of microturbines, the major considerations are higher power density as well as higher efficiency for energy-saving. In order to achieve higher efficiency, recuperated systems which recover the exhaust heat then become mandatory and the paramount requirements for the recuperator are high effectiveness and low pressure loss. Here, the thermal design and model analysis of a proposed Swiss-roll recuperator for future higher efficiency microturbines were made with both theoretical approach and numerical simulation. The proposed Swiss-roll recuperator is basically the primary surface type. It is composed of two flat plates that are wrapped around each other, creating two concentric channels of rectangular cross-section. The characteristics of Swiss-roll recuperator resemble the counter-flow spiral plate heat exchanger and have the excellent performance in effectiveness and pressure-loss. From a theoretical analysis, the thermal characteristics of the Swiss-roll recuperator were investigated and its preliminary designs at a given effectiveness for an innovative micro gas turbine were also demonstrated, including the determination of the number of turns, the corresponding channel widths and the required number of transfer unit (NTU). The consequent pressure loss through the recuperator was also predicted. For a given design of the recuperator, the model simulation was then made to provide the insights and needs for further improving the performance of the Swiss-roll recuperator.     

Low-cost compact primary surface recuperator concept for microturbines

By the year 2000, microturbines in the 25–75 kW power range are projected to find acceptance in large quantities in the distributed power generation field, their major attributes include low emissions, multifuel capability, compact size, high reliability and low maintenance. For this type of small turbogenerator, an exhaust heat recovery recuperator is mandatory in order to realize a thermal efficiency of 30% or higher. The paramount requirements for the recuperator are low cost and high effectiveness. These characteristics must be accomplished with a heat exchanger that has good reliability, high performance potential, compact size, light weight, proven structural integrity, and adaptability to automated high volume production methods. In this paper, a recuperator concept is discussed that meets the demanding requirements for microturbines. The proposed stamped and folded metal foil primary surface recuperator concept has as its genesis, a prototype heat exchanger module that was fabricated as part of an energy research program in Germany over two decades ago. This novel heat exchanger approach was clearly ahead of its time, and lacking an application in the late 1970s was, alas, not pursued and commercialized. Based on this earlier work, a further evolution of the basic concept is proposed, with emphasis placed on the following: (1) minimization of the number of parts, (2) use of a continuous fabrication process, (3) matrix overall shape and envelope flexibility (annular or platular geometry), (4) ease of turbogenerator/recuperator integration, and (5) a later embodiment of a bi-metallic approach, towards the goal of establishing a compact and cost-effective recuperator for the new class of very small gas turbines that are close to entering service. For a representative microturbine, an annular recuperator would have only five basic parts. The matrix cartridge would be essentially a plug-in component, analogous to an automobile oil filter element. In this paper, the important role that the recuperator has on turbogenerator performance is discussed, together with a summary of the early prototype heat exchanger development. The major requirements, features and cost goals for a compact primary surface recuperator for microturbine service, are also covered.     

一次表面回热器进气结构对物流分配性能的影响

不合理的进气结构造成一次表面回热器(PSR)内部物流分配不均匀,影响同热器内部流体的流动和传热效果.本文提出了具有导流片的进气结构,并在尽可能地保证出口截面速度均匀分布的前提上,开展了不同进气结构对回热器芯体入口物流分配影响的研究.结果表明,在所研究的雷诺数范围内,改进后的进气结构中各通道出口截面速度的最大波动只有14...     

Optimal design of plate-and-frame heat exchangers for efficient heat recovery in process industries

The developments in design theory of plate heat exchangers, as a tool to increase heat recovery and efficiency of energy usage, are discussed. The optimal design of a multi-pass plate-and-frame heat exchanger with mixed grouping of plates is considered. The optimizing variables include the number of passes for both streams, the numbers of plates with different corrugation geometries in each pass, and the plate type and size. To estimate the value of the objective function in a space of optimizing variables the mathematical model of a plate heat exchanger is developed. To account for the multi-pass arrangement, the heat exchanger is presented as a number of plate packs with co- and counter-current directions of streams, for which the system of algebraic equations in matrix form is readily obtainable. To account for the thermal and hydraulic performance of channels between plates with different geometrical forms of corrugations, the exponents and coefficients in formulas to calculate the heat transfer coefficients and friction factors are used as model parameters. These parameters are reported for a number of industrially manufactured plates. The described approach is implemented in software for plate heat exchangers calculation.     

Effect of Geometry and Flow Conditions on Particulate Fouling in Plate Heat Exchangers

This article describes particulate fouling experiments performed on small-scale and full-scale plate heat exchangers for three different corrugation angles (30 deg, 45 deg and 60 deg). The velocity effect has been studied as well as the particle type and concentration effects. The test duration ranges between 20 and 1,500 h in order to reach asymptotic behavior. The results clearly indicate that the corrugation angle has a major influence on the asymptotic fouling resistance. Increasing the corrugation angle leads to lower values for the fouling resistance. Furthermore, for a given corrugation angle, the asymptotic fouling resistance is inversely proportional to the velocity squared. Finally, the asymptotic fouling resistance is proportional to the particle concentration. Fouling mitigation can be obtained by taking into account at the design stage the heat exchanger geometry and fluid velocity.