寒冷地区空气源吸收式热泵性能提高途径及对比分析

空气源吸收式热泵对于北方供暖的意义重大。为了提高空气源吸收式热泵在低温环境下的可靠性和能效,提出了双级吸收式热泵、双级耦合吸收式热泵和增压吸收式热泵。通过建模和模拟分析,对这三种途径在不同环境温度下的性能进行了对比分析。若采用风机盘管末端,当采暖期内气温低于-25℃的时间很少时,双级耦合热泵的性能最好;否则可以考虑采用双级空气源吸收式热泵。室外设计温度为-15℃和-30℃时,空气源吸收式热泵的一次能源效率分别比燃煤锅炉高28%和19%。若采用地板辐射末端,则增压吸收式热泵的能效最高,室外设计温度为-15℃和-30℃时,一次能源效率可达0.953和0.874,分别比燃煤锅炉高36%和25%。考虑整个采暖期内气温较高时热泵的性能较好,则增压空气源吸收式热泵用于地板辐射采暖的节能潜力更为可观。     

板式蒸发式冷凝器传热传质的数值模拟

根据能量守恒和质量守恒定律,对板式蒸发式冷凝器中制冷剂、冷却水与空气之间的传热传质过程,建立了热质交换过程的二维数学模型,由此分析板式蒸发式冷凝器中冷却水温度、空气温度和空气含湿量等参数的分布规律,以及空气流速、干湿球温度、冷却水喷淋密度和冷凝温度对板式蒸发式冷凝器热流密度的影响,并将模拟结果通过实验进行了验证,两者之间的误差在10%以内。研究表明:板式蒸发式冷凝器的热流密度随进口空气流速的增加而增大,随湿球温度的升高而减小,几乎不受进口空气干球温度的影响;热流密度随着冷却水喷淋密度的增加逐渐增大,但增大至一定量后不再对热流密度有明显影响;冷凝温度越高,其热流密度越大。上述结论对板式蒸发式冷凝器的优化设计具有指导意义。     

插画在品牌形象创建中的作用

一、插画作为设计语言的概念与研究现状 当下的插画设计在某种程度上是一个颇为尴尬的设计门类,既因缺乏绘画艺术的纯粹性而被艺术界拒之门外,又被平面设计界认为风雅有余实用性不足而不属同门。在现代汉语词典中,“插画”词条的解释为“艺术性的插图”;“插图”词条的解释为“插在文字中间帮助说明内容的图画,     

Finite-temperature Effect in Phase Transition to Superfluidity for Bose–Einstein Condensates in a 1-D Optical Lattice

We experimentally study the phase transition of ⁸⁷Rb Bose–Einstein condensates adiabatically loaded to a combined trap of a 1D optical lattice and a magnetic trap. The phase coherence property of this system is probed by recording the interference pattern of the expanded atomic cloud suddenly released from the combined trap. We show that as the temperature is sufficiently low (below the critical temperature T _C ), an interference pattern has a “peak on a peak” feature which is a true signature of macroscopic superfluid states. The normal gas only contributes to the broad background and three wide peaks in an interference pattern. These observations qualitatively agree with the recent theoretical predictions (Diener et al. in Phys. Rev. Lett. 98:180404, 2007; Kato et al. in Nat. Phys. 4:617, 2008). We also computed both the critical temperature and the interference pattern for a practical combined trap as ours in the tight-binding limit, and the numerical results are consistent with our experimental observations.     

Microstructure Evolution and Mechanical Behavior of Cold-Sprayed,Bulk Nanostructured Titanium

To provide insight into the microstructural evolution and mechanical behavior of bulk nanostructured Ti, we used cold gas dynamic spraying of Ti particles to synthesize thick coatings (e.g., >10 mm in thickness). Accordingly, the grain size, lattice parameter, lattice strain, residual stress, porosity, microhardness, tensile, and compressive behavior of the bulk Ti deposits before and after annealing were comparatively analyzed. Our results show that the microstructure of the as-sprayed bulk Ti was characterized by a grain size of ~60 nm, lattice expansion (~2 pct for \( a \) and ~3 pct for \( c \) ), lattice strain (~1.65 × 10^?5), and residual compressive stress (~53 MPa). Moreover, annealing of the as-deposited bulk Ti led to a significant decrease in lattice expansion, lattice strain, and residual stress, whereas porosity remained unchanged (~11 pct). The mechanisms of grain growth, as well as the evolution of particle interfaces during annealing, were also investigated. In terms of mechanical behavior, the as-deposited bulk Ti exhibited a very low modulus (52 GPa) with relatively high tensile and compressive strength values (180 and 850 MPa, respectively). Annealing in the temperature range of 1023 K to 1173 K (750 °C to 900 °C) led to a significant increase of tensile and compressive strength (to 380 MPa and more than 1200 MPa, respectively). Finally, annealing resulted in a slight increase of elastic modulus, which was rationalized on the basis of changes in pore geometry in the bulk Ti deposits.     

Constrained multi-objective optimization using constrained non-dominated sorting combined with an improved hybrid multi-objective evolutionary algorithm

Constrained multi-objective optimization problems (cMOPs) are complex because the optimizer should balance not only between exploration and exploitation, but also between feasibility and optimality. This article suggests a parameter-free constraint handling approach called constrained non-dominated sorting (CNS). In CNS, each solution in a population is assigned a constrained non-dominated rank based on its constraint violation degree and Pareto rank. An improved hybrid multi-objective optimization algorithm called cMOEA/H for solving cMOPs is proposed. Additionally, a dynamic resource allocation mechanism is adopted by cMOEA/H to spare more computational efforts for those relatively hard sub-problems. cMOEA/H is first compared with the baseline algorithm using an existing constraint handling mechanism, verifying the advantages of the proposed constraint handling mechanism. Then cMOEA/H is compared with some classic constrained multi-objective optimizers, experimental results indicating that cMOEA/H could be a competitive alternative for solving cMOPs. Finally, the characteristics of cMOEA/H are studied.     

板翅式换热器封头型式的改造

采用计算流体力学(CFD)方法研究大型板翅式换热器封头内的流体流动,根据流动特征提出在封头段加入导流分布板改善流动分布均匀性的方法.与未加入导流分布板比较结果显示,加入导流分布板后,流体分布得到改善,传热系数亦有显著提高.     

The Influence of Ni-Coated TiC on Laser-Deposited IN625 Metal Matrix Composites

IN625 Ni-based metal matrix composites (MMCs) components were deposited using Laser Engineered Net-Shaping (LENS) with Ni-coated and uncoated TiC reinforcement particles to provide insight into the influence of interfaces on MMCs. The microstructures and spatial distribution of TiC particles in the deposited MMCs were characterized, and the mechanical responses were investigated. The results demonstrate that the flowability of the mixed powders, the integrity of the interface between the matrix and the TiC particles, the interaction between the laser beam and the TiC ceramic particles, and the mechanical properties of the LENS-deposited MMCs were all effectively improved by using Ni-coated TiC particles.     

缓蚀剂在延迟焦化装置的应用

对中国石油化工股份有限公司天津分公司炼油部延迟焦化装置使用缓蚀剂的原因进行了分析,并对缓蚀剂的使用原理、方法和标定情况进行了介绍,还介绍了HS-IHX型缓蚀剂在延迟焦化装置的试用情况,并对其效果进行了评价.