Thermo-economics for endoreversible heat-engines

The thermoeconomics of endoreversible heat engines has been studied based on the linear phenomenological heat-transfer law [i.e., the heat flux Q ∝ Δ(1/T), where T is the absolute temperature]. Analytical formulae for profit, the maximum profit and the corresponding efficiency are derived.     

燃煤电厂烟气冷凝除尘试验研究

通过在某300 MW燃煤机组湿法烟气脱硫(WFGD)系统的脱硫塔出口搭建烟气旁路,测试具有冷凝除尘作用的塑料型换热管束的传热系数、烟气侧阻力特性及除尘性能。结果表明:管束传热系数在350 W/(m^2·K)以上,烟气侧阻力随烟气流速增加而明显增大,除尘效率达到58.6%,出口粉尘质量浓度在4.5 mg/m^3左右;采用冷凝除尘技术不仅可以除尘,还能够回收烟气中的热量和水分。     

关于搅拌设备设计中的几个问题

针对搅拌设备设计中有关搅拌功率、搅拌槽的传热和固液悬浮搅拌的问题 ,通过自身的设计实践 ,对其中的相关内容和参数 ,提出自己的看法     

加氢裂化REAC的仿真失效分析

通过对典型工况下工艺过程仿真分析、传热计算并结合CFD数值模拟,分析了热高分空冷器的失效形式与管束失效部位,并运用远场涡流检测技术验证结论的可靠性。结果表明：热高分空冷管束的失效主要由高腐蚀性介质下的流体冲蚀造成;热高分空冷系统中液态油相的黏度较低,可以降低溶液的腐蚀性和管壁所受的剪应力;典型工况下距空冷器入口5.8m处溶液的腐蚀性强、管壁受到的剪应力大,是容易出现局部冲蚀减薄的危险区域。     

回热器对HAT循环影响的分析

目前对HAT循环中回热器的理论分析大多采用传热温差法和表征回热器特性的回热度分析的方法。针对这两种不同的分析方法分别进行了计算,比较分析了它们对HAT循环的影响,结果表明,传热温差法更加适合于对HAT循环进行理论分析,但应当注意传热温差的选取。而回热度法更多应用于回热器的设计。     

原油管道中加热炉系统的应用

介绍了西部原油管道两种常用加热方式的原理,对两种加热方式的优缺点进行了对比,并根据工程实例对加热方式的应用情况进行了总结.     

基于PHOENICS的地下工程岩土耦合传热动态模拟

传统的静态极限设计方法已经不能满足地下工程内部环境保障系统设计的经济合理有效要求。本文主要针对深埋地下上程的间歇加热工况,对工程内部环境与周围岩石的温度分布及耦合传热情况进行动态分析,并进一步指导动态设计。简化间歇机制下深埋拱形地下建筑的数学物理模型,采用整场求解方法,通过建立流体和固体区域的统一控制微分方程,将复杂的固体导热与流体对流换热通过彼此互为边界条件耦合起来。整个数值模拟过程采用大型计算软件PHOENICS3．4进行求解,并对现有软件程序加以改进得出经验模型,使CFD软件能更广泛应用于地下工程的通风空调设计中,为求解非稳态的导热和对流换热耦合问题提供了一种新的可行研究方法。此外还具体分析了进风风速、室内热源等方面的因素对温度分布的影响。     

Wok design: thermal-performance influencing parameters

Experimental studies have been performed to investigate the thermal performances of woks fabricated from materials with different thermal conductivities and surface emissivities. A pre-mixed air/butane flame impinged vertically upwards upon a flat impingement-plate’s (to simulate the wok’s flat-bottom) surface under laminar-flow conditions. The operation parameters of the premixed flame were kept constant (i.e., Reynolds number = 1200; equivalence ratio = 1; and nozzle-to-plate distance = 5). In order to examine the effect of conduction, three materials, namely red brass (k = 61 W/mK), bronze (k = 26 W/mK) and stainless steel (k = 14.9 W/mK), were considered. Because of the lower thermal-conductivity and hence higher conduction–resistance, a significantly lower heat-flux would ensue over the stagnation region for the stainless-steel wok. However, there were no significant differences in the heat-flux distributions in the wall-jet regions for the stainless-steel, bronze and red-brass impingement plates. To examine the effects of radiation, three red-brass impingement plates with surface-emissivities of either 0.1, 0.38 or 0.98 were tested experimentally. Different surface-emissivities have only slight impact, on the heat-flux distributions on the wok’s surface. In addition, there were only insignificant differences in the heat-flux and temperature distributions in the wall-jet regions of the impingement plates fabricated of the same material but with different surface-emissivities.     

Optimal shape profiles for cooling fins of high and low conductivity

We present a numerical approach able to capture the dependence of the optimal shape profiles of thermal fins on the conductivity parameters. We consider the two-dimensional cross-section of a periodic array of fins and involve the third dimension via the thermal boundary layer. The highly conductive fins converge to “sharp-pointed”, narrow base shapes while the low conductivity ones prefer blunted, wide base fins. The optimal shapes we obtain are similar to the shapes of intestinal villi and stegosaurus plates. A meshfree method, coupled with a gradient-based optimization algorithm, is used to handle the significant shape changes from a simple, generic initial guess to the final, optimal shape. We reach the optimal shapes without remeshing.     

Exergy-based ecological optimization of linear phenomenological heat-transfer law irreversible Carnot-engines

The optimal exergy-based ecological performance of a generalized irreversible Carnot-engine with losses due to heat-resistance, heat leakage and internal irreversibility, in which the heat-transfer between the working fluid and the heat reservoirs obeys a linear phenomenological heat-transfer law, is derived by taking an exergy-based ecological optimization criterion as the objective. This consists of maximizing a function representing the best compromise between the power output and entropy-production rate of the heat engine. A numerical example is given to show the effects of heat leakage and internal irreversibility on the optimal performance of the generalized irreversible heat-engine. The results provide theoretical guidance for the design of practical engines.