Summer off-peak performance enhancement for rows of fixed solar thermal collectors using flat reflective surfaces

Collectors for building-scale solar thermal systems are generally fixed, so that energy capture is optimized over the course of a year, but is generally not optimal on any given day. In particular, abundant sunlight available during summer mornings and late afternoons is not captured. Moreover, ancillary systems (pumps, piping, etc.) are designed to operate at peak, meaning that they are underutilized for the majority of the time. In this study, reflective surfaces are used to reflect morning sunlight onto fixed collectors. The orientation of the reflectors is optimized using simulation. The simulation results are corroborated by experimental data from a 150 kW_t system located on the roof of the University of New Mexico’s Mechanical Engineering system in Albuquerque, New Mexico. The study also considers economic and performance benefits deriving from using reflectors in combination with fixed collectors. It is found that the simulation correctly predicts system performance, and that a reduction in the cost of solar cooling of approximately 20% can be obtained by installation of the mirrors, without adding any extra components to the system. Perhaps the most important outcome of this study is that performance of booster mirrors is extremely sensitive to local climatic conditions and to the constraints placed on the positioning and orientation of the booster reflectors, making it impossible to generalize findings for one particular location. Thus, computer simulation is essential for designing and optimizing thermal systems with booster reflectors.     

营钢8流小方坯连铸机工艺设计

介绍了五矿营钢8机8流方坯连铸机工艺设计特点、工艺流程、装备水平、工艺布置和主要物流路线，以及多流铸机情况下适应不同热送和下线比例的复杂出坯系统；详细分析了与同车间板坯连铸机交替使用同一给排水系统情况下的系统配置。     

风电主齿箱系统低温待机方案的研究

以1.5 MW风力发电机组为例,对目前风电主齿箱系统低温环境待机困难的现状进行研究,通过该类主齿箱系统待机时加热与散热的计算,对循环周期内各时段润滑油的温度进行推算,根据推算结果,解释了主齿箱系统低温环境待机困难的主要原因,并提出了低温待机方案的改进策略.     

On the selection and design of the proper roof pond variant for passive cooling purposes

The present paper aims to fully summarize the current scientific and technological experience focusing on the comparative characteristics of roof pond variants. The design guidelines and pond characteristics provide the opportunity to make the proper decision of a roof pond variant for cooling purposes. The following systems are under detailed investigation: covered/uncovered pond with/without sprays, skytherm, energy roof, coolroof, walkable pond, wet gunny bags, cool-pool shaded and ventilated pond. A brief background of the motivation behind the creation of the above variants is provided. The advantages and disadvantages of ponds as well as the design considerations and state of the art are discussed. Additionally, in the present study a detailed comparison is performed in terms of effectiveness and cooling demand reduction. A complete set of criteria affecting the choice of the proper roof pond are also analyzed. Finally, a decision support flowchart, is provided based on the various criteria and parameters.     

加热炉炉内悬臂辊道设计

介绍了目前国内比较常用的几种悬臂辊结构。     

Emulation-based transient thermal modeling of 2D/3D systems-on-chip with active cooling

State-of-the-art devices in the consumer electronics market are relying more and more on Multi-Processor Systems-On-Chip (MPSoCs) as an efficient solution to meet their multiple design constrains, such as low cost, low power consumption, high performance and short time-to-market. In fact, as technology scales down, logic density and power density increase, generating hot spots that seriously affect the MPSoC performance and can physically damage the final system behavior. Moreover, forthcoming three-dimensional (3D) MPSoCs can achieve higher system integration density, but the aforementioned thermal problems are seriously aggravated. Thus, new thermal exploration tools are needed to study the temperature variation effects inside 3D MPSoCs. In this paper, we present a novel approach for fast transient thermal modeling and analysis of 3D MPSoCs with active (liquid) cooling solutions, while capturing the hardware-software interaction. In order to preserve both accuracy and speed, we propose a close-loop framework that combines the use of Field Programmable Gate Arrays (FPGAs) to emulate the hardware components of 2D/3D MPSoC platforms with a highly optimized thermal simulator, which uses an RC-based linear thermal model to analyze the liquid flow. The proposed framework offers speed-ups of more than three orders of magnitude when compared to cycle-accurate 3D MPSoC thermal simulators. Thus, this approach enables MPSoC designers to validate different hardware- and software-based 3D thermal management policies in real-time, and while running real-life applications, including liquid cooling injection control.     

VB6.0编写Bi-Cd体系步冷曲线演示程序

采用Visual Basic 6.0编写了Bi-Cd双金属体系步冷曲线的教学演示程序。程序结合物理化学相关数据,描述了不同条件下Bi-Cd体系的步冷曲线。在程序中,通过调节的金属质量比例和演示程序速度,可以详细分析热分析方法中体系Bi-Cd体系相与温度的变化,为教学提供了直观生动,可交互控制的演示环境。     

Estimation of passive cooling efficiency for environmental design in Brazil

An estimation of passive cooling techniques was conducted for 14 cities in Brazil, using a fairly accurate algorithm that accounts for heat conduction, convection, radiation, and evaporation; this was done to determine the amount of heat gain/loss of room air, defined as a particular quantitative index for passive techniques. Heat gains and losses were calculated for four envelope conditions - namely, insulated, high-albedo, wet surface, and a combination of the previous two - and compared to a case assumed to be the standard condition. A conclusion drawn was that a passive design is efficient in decreasing the need for cooling in typical dwellings in Brazil; solutions should differ with regional climate characteristics. In semi-arid areas, evaporative cooling showed the best results. Reduced heat gain was found during the warm seasons for all cities, along with increased heat gain during the cool seasons for mid-latitude cities. In particular, a combination of high-albedo enveloping and evaporation can greatly decrease heat gain in building walls. High-albedo surfaces in the sub-tropical areas found in southern Brazil are more efficient. It is suggested that passive techniques should be conceived in such a way so as to work during the cooling season and be disabled during mild ones.     

减小圆锥滚子轴承套圈锥度变形的方法

圆锥轴承套圈淬火后易产生锥度变形，通过改变摆放方法，使淬火时冷却均匀，减少锥度变形，大大降低因锥度变形率超差而造成的废品。     

Study on cyclic characteristics of silica gel–water adsorption cooling system driven by variable heat source

The fluctuation of heat source influences the performance of adsorption cooling systems greatly in practical applications. This paper mainly investigates the cyclic characteristics of silica gel–water adsorption cooling system under the condition of general variable heat source, in order to explore the system characteristics and access the related operation strategies. In this work, all practical variable heat sources are regarded as the combination of two different changes: the slow time-varying change (long change) and the fast time-varying change (short change). Based on a transient model of adsorption chiller verified by experiments, the characteristics of adsorption cooling system under both the two types of changes are presented. With the slow time-varying change, the heat source variation rate is a key factor that influences the system performance greatly. And for the fast time-varying change, concentration is being focused on the influence on chiller desorption process. The methods to minimize this effect, such as to change desorption time, is discussed. Moreover, the water tank capacity plays a very important role under both slow time-varying and fast time-varying heat sources. The analysis in this work will eventually contribute to operation strategies under different conditions and methods to decrease the influence of heat source fluctuation.