用于光伏直驱离心式冷水机组的变频器冷却性能试验研究

本文针对具有相变冷却方式的光伏直驱冷水机组的变频器搭建实验系统,研究散热性能,并优化设计。实验系统由水系统、供电系统组成,供电系统包括光伏模拟电源、电网。实验使变频器产生不同发热状况,结果表明,在500 k W空调运行模式中,整流模块稳定在45.0℃;520 k W光伏发电模式中,冷却输出无法匹配负荷变化速率,整流模块温度在23.2℃~57.3℃波动,缩短调节周期后温度稳定在42.0℃;在低功率运行中,冷却输出能力过大、柜内露点温度高使模块温度低于13.0℃并发生凝露,采取提高除湿能力、限制冷却输出措施后未发生凝露。优化后的设计将提高变频器冷却性能。     

立式敞开式冷藏陈列柜蒸发器结霜特性的实验研究

实验测试不同环境温湿度工况下立式敞开式冷藏陈列柜蒸发器的蒸发温度、冷风幕送回风温度、蒸发器的凝水量及结霜水量,以研究环境温湿度变化对柜性能的影响.研究表明,当柜在较高环境相对湿度运行时,柜内蒸发器表面结霜量很少,冷空气中80%以上的析水以凝露形式形成.此时停机融霜没有必要,并使柜温上升过高.     

房间空调器产生凝露的原因及改善方法

对房间空调器室内机产生凝露的原因进行分析,并通过试验研究提出改善方法。结果表明:通过合理确定制冷剂充注量,以及遵循蒸发器回路设计原则(每一路出口和每一路进口处于同一气流经过的水平面)能够改善凝露问题。另外,从控制系统方面考虑,通过增量式PID控制算法调节压缩机频率使盘管温度高于空气露点,可以明显改善凝露;从安装等方面考虑,密封性、保温性以及电加热安装角度等对凝露均有重要影响。     

柜式空调器凝露问题改善研究

本文对柜式空调器4类凝露问题:内机内外表面产生凝露并滴落至地面、内机送风有水吹出、凝结水进入显示屏/电脑板等电器部件、漏水的原因进行了分析,并针对这些问题给出了包括控制方法优化、结构隔热保温挡水、系统调整、送风流场改善等措施:对凝结水漏水问题改善则指出:需重点从主接水盘、副接水盘、蒸发器、排水管、联机管等进行检讨优化。     

分体挂壁空调器吹水的分析与应用

凝露问题是空调质量问题之一,严重影响用户的生活和工作环境。凝露的主要表现为:外表面凝露和风道内表面凝露并吹出。本文通过理论分析,从结构以及系统方面提出改善风道内表面凝露吹水的方法,并且在一款机型上验证效果。     

压缩机表面产生凝露的原因及其解决措施

变频多联机中距离室内机近的压缩机表面在运行中出现凝露现象,并伴随压缩机内油翻泡,油面下降。从理论方面分析该现象：在名义制冷、最大制冷工况下,制冷剂循环量没有控制好,导致过多的制冷剂进入压缩机后继续蒸发,温度降低到露点温度以下,从而出现压缩机表面凝露。为此,提出相应的控制措施,较好地解决了该问题,对保证多联机系统的稳定安全可靠运行具有一定的指导意义。     

商用冷柜如何解决凝露问题

本文主要对商用冷柜产生凝露问题的原因进行了全面地分析,并对解决凝露问题提出了两种办法,即避免在冷柜玻璃内外表面形成温差,采用钢化热反射玻璃;在玻璃窗上贴几条肉眼不可见的电加热膜,使用防露电热中空玻璃。这两种办法是目前解决凝露问题最先进、最有效、最经济的办法。它不仅大大提高了冷柜的展示性,而且还有效地节约了能源。另外对一些中温冷藏柜可用普通曲面玻璃加防结露风扇解决凝露问题。     

房间空调器凝露问题的分析

对空气凝露的产生原理及房间空调器凝露性能试验中出现的现象、问题的原因进行了分析,并提出有效的改进方法.     

冷藏柜门部位凝露的机理及克服途径的理论计算

冷藏柜的凝露问题多发生在门部位。由于门部位的凝露造成柜体外壁锈蚀,油漆脱落,门铰链生锈失灵等,严重影响了冷藏柜的使用寿命和使用效果。本文从理论分析入手,对影响柜门部位凝露的机理进行了探讨,对常见的解决办法,如埋设高压管和电热丝进行了理论计算,并对相关的影响因素进行了讨论。     

基于TRIZ的辐射供冷表面凝露防控技术研究

辐射供冷可利用高温冷源为房间降温,具有高效、节能、舒适等优点,在温湿度独立控制空调系统中具有重要作用。实际运行中辐射供冷表面可能因各种原因出现凝露现象,影响室内环境和空调效果。本文应用TRIZ对夏季辐射表面凝露问题进行系统分析,将实际问题转化为标准问题,运用TRIZ的理想解、分离原理、矛盾矩阵和物-场模型等方法,得出12种解决方案,并通过与已有的研究工作进行对比验证,为解决夏季辐射供冷表面凝露问题、辐射供冷技术研究和设备开发提供新的思路和解决方案。     

柔性转子自动动平衡的寻优控制

介绍了一种转子自动动平衡装置的基本结构,提出了两种基于多校正平面柔性转子自动动平衡的随机寻优控制策略(坐标轮换法和单纯形法)及其控制用目标函数,并对其平衡效率和有效性进行了理论分析和仿真研究。结果表明,两种寻优控制具有较好的精度和收敛性,将影响系数法和随机寻优相结合的控制策略具有较高的精度和效率,且易于实现。     

陈列柜摆放位置对荔枝货架期品质的影响

目的研究不同销售方式及摆放位置对货架期荔枝果实品质变化的影响,为荔枝果实货架期保鲜和销售货架设计提供一定的参考。方法在敞开式陈列柜和常温货架上,以盒装的"怀枝"荔枝果实为实验材料,开展荔枝果实贮藏试验,研究货架期72h内荔枝果实分别放置在冷藏陈列柜不同位置和常温货架上品质的变化情况。结果在货架期内,冷藏陈列柜第4层和常温货架贮藏荔枝的果实褐变指数高于其他陈列位置,好果率低于其他陈列位置;冷藏陈列柜第4层的荔枝果实质量损失率的上升速率最快,72 h后上升至11.01%,其果皮色差a*值最小;第3层荔枝果实的质量损失率上升得最缓慢,其果皮色差a*值最大;常温货架荔枝的果皮色差L*值最大,其果肉的可溶性固形物含量和硬度最低;不同销售方式及摆放位置对荔枝果肉可滴定酸含量的变化影响不显著。结论在冷藏陈列柜中、上部摆放位置贮藏能相对更好地保证荔枝果实的销售品质,冷藏陈列柜的结构优化及其对温湿度场分布特性的影响将会是今后的研究方向。     

轴心受压钢柱抗火设计的优化分析

基于"双重优化设计"概念给出了轴心受压钢柱抗火优化设计方案,利用有限元软件ANSYS的APDL语言及其优化设计模块对其进行了截面尺寸和抗火保护优化设计。分析中采用了两种优化设计方案,即在常温和一定临界温度条件下对轴心受压钢柱进行截面尺寸及抗火保护优化设计。通过对两种设计方案的优化结果进行比较和分析,得到了高温下轴心受压钢柱的抗火优化设计结果随温度变化的规律,给出了考虑经济成本条件下如何选择更加经济合理的优化设计方案的建议。分析结果表明,给出的优化方案可以得到安全、经济、可靠的设计结果,能够节省钢材用量和防火保护材料用量。     

血液滤白柜的温度试验研究

为了保障输血安全,血液需要进行滤白处理,滤白柜可以为血液滤白提供一定的温度条件。本文在一定的试验条件下,对原血液滤白柜进行降温速度试验和温度控制试验,发现柜内最低温度为3.64℃,最高温度高于7℃,平均温度在5℃左右,温度波动大,偏离血液的保存温度4℃±2℃。对血液滤白柜敞口部分增加隔热帘后,柜内温度分布有了明显的改善,箱内最低温度为2.62℃,平均温度在4℃左右,温度波动较小。     

The impact of geometric structure and flow arrangement on the performance of CO2 evaporators in multi-deck medium temperature display cabinets

The CO₂ refrigerant is widely applied in retail refrigeration systems to replace HFC fluids such as R404A, but its system performance requires further improvement. One feasible method would be to pinpoint the matching components of the system, in particular its evaporator coils. This paper focuses on the potential optimization of the CO₂ evaporator design in an existing multi-deck medium temperature display cabinet charged previously with R404A refrigerant. To achieve this target, a display cabinet model with an integrated CFD and detailed evaporator sub models was utilized. This model could readily imitate the actual cabinet performance under varied operating conditions and component designs. Various design options of the CO₂ cabinet evaporator were considered and their impacts on the cabinet performances were predicted by the integrated model. Ultimately, the optimized designs of CO₂ cabinet evaporator coil geometries and refrigerant side operating parameters have been attained.     

A simple and effective heuristic for the resource constrained project scheduling problem

This paper investigates the development and application of a simple heuristic to the resource constrained project scheduling problem (RCPSP). This computer heuristic, which is based on the COMSOAL heuristic, constructs a feasible solution at each iteration and chooses the best solution of several iterations. Although COMSOAL was originally a solution approach for the assembly-line balancing problem, it can be extended to provide solutions to the resource allocation problem. The Modified COMSOAL technique presented in this paper uses priority schemes intermittently with a random selection technique. This hybrid of randomness and priority scheme allows a good solution to be found quickly while not being forced into the same solution at each iteration. Several different priority schemes are examined within this research. The COMSOAL heuristic modified with the priority schemes heuristic was tested on several established test sets and the solution values are compared with both known optimal values and the results of several other resource allocation heuristics. In the vast majority of cases, the Modified COMSOAL heuristic outperformed the other heuristics in terms of both average and maximum percentage difference from optimal. The Modified COMSOAL heuristic seems to have several advantages over other RCPSP heuristics in that it is easy to understand, easy to implement, and achieves good results.     

微通道冷凝器在展示柜上的应用研究

针对卧式冷藏展示柜能耗较高,在环境温度升高时制冷效果下降等问题,提出采用传热系数较高的微通道换热器作为冷藏展示柜的冷凝器。实验对比结果表明:新改进的展示柜解决了高温工况下制冷效果下降和压缩机不停机等问题,展示柜的能耗也显著降低。在环境温度为16、25、32℃工况下空柜测试,与管外面积相差在3%以内丝管式冷凝器相比,微通道冷凝器分别节能11. 67%、24. 85%、45. 64%,开停比分别下降7. 20%、14. 90%、31. 70%。     

Skill Optimization Algorithm: A New Human-Based Metaheuristic Technique

Metaheuristic algorithms are widely used in solving optimization problems. In this paper, a new metaheuristic algorithm called Skill Optimization Algorithm (SOA) is proposed to solve optimization problems. The fundamental inspiration in designing SOA is human efforts to acquire and improve skills. Various stages of SOA are mathematically modeled in two phases, including: (i) exploration, skill acquisition from experts and (ii) exploitation, skill improvement based on practice and individual effort. The efficiency of SOA in optimization applications is analyzed through testing this algorithm on a set of twenty-three standard benchmark functions of a variety of unimodal, high-dimensional multimodal, and fixed-dimensional multimodal types. The optimization results show that SOA, by balancing exploration and exploitation, is able to provide good performance and appropriate solutions for optimization problems. In addition, the performance of SOA in optimization is compared with ten metaheuristic algorithms to evaluate the quality of the results obtained by the proposed approach. Analysis and comparison of the obtained simulation results show that the proposed SOA has a superior performance over the considered algorithms and achieves much more competitive results.     

Optimized partitioning of unstructured finite element meshes

We address the problem of automatic partitioning of unstructured finite element meshes in the context of parallel numerical algorithms based on domain decomposition. A two-step approach is proposed, which combines a direct partitioning scheme with a non-deterministic procedure of combinatorial optimization. In contrast with previously published experiments with non-deterministic heuristics, the optimization step is shown to produce high-quality decompositions at a reasonable compute cost. We also show that the optimization approach can accommodate complex topological constraints and minimization objectives. This is illustrated by considering the particular case of topologically one-dimensional partitions, as well as load balancing of frontal subdomain solvers. Finally, the optimization procedure produces, in most cases, decompositions endowed with geometrically smooth interfaces. This contrasts with available partitioning schemes, and is crucial to some modern numerical techniques based on domain decomposition and a Lagrange multiplier treatment of the interface conditions.     

机柜服务器热管背板换热性能的试验研究

通过测试热管背板系统在不同进风温度、制冷剂冷凝单元（RCU）冷冻水进水温度及水流量工况下的换热能力,分析环境温度升高、系统供水不足等对高密度机柜服务器安全运行的影响,采用模拟负载机柜测试机房机柜安装热管背板后不同位置的换热能力。结果表明,热管背板系统对进风温度、冷冻水温度及流量具备良好的换热适应性,发热量大的服务器优先安装在机柜中下部,发热量小的服务器安装在机柜上部,可以最大限度发挥热管背板的换热能力。