Mixed Thermocapillary and Forced Convection Heat Transfer Around a Hemispherical Bubble in a Miniature Channel—A 3D Numerical Study

It has been established that for certain conditions, such as microgravity boiling, thermocapillary Marangoni flow has associated with it a significant enhancement of heat transfer. Typically, this phenomenon was investigated for the idealized case of an isolated and stationary bubble resting atop a heated solid that is immersed in a semi-infinite quiescent fluid or within a two-dimensional cavity. This article presents a three-dimensional numerical study that investigates the influence of thermal Marangoni convection on the fluid dynamics and heat transfer around a bubble during laminar flow of water in a minichannel. This mixed thermocapillary and forced convection problem is investigated for channel liquid inlet velocity of 0.01 m/s to 0.03 m/s and Marangoni numbers in the range of 10 to 300 under microgravity conditions. Three-dimensional effects become particularly important on the side and rear regions of the bubble. The thermocapillary forces accelerate the flow along almost the entire bubble interface. The hot core fluid from the heated bottom wall region is forced inward and propelled upward into the thermocapillary jet above the bubble. It can be quantified that the influence of thermocapillary flow on heat transfer enhancement shows an average increase by 40% at the downstream of the bubble and by 60% at the front and rear regions. This heat transfer enhancement depends mainly on the temperature differential as the driving potential for thermocapillary flow and bulk liquid velocity.     

SHL_(1200)~(14)—1.4/130/70—AⅡ锅炉运行诊断及改造

SHL_(1200)~(14)—1.4/130/70—AⅡ型锅炉是北方地区中小型区域集中供热锅炉房采用的主要炉型之一,其运行的经济性及技术性能的优劣会直接影响供热区域人民生活水准及供热部门的经济效益。作者对东北地区两个城市三个锅炉房的七台该型锅炉的调查发现,均存在很严重的出力不足、热效率低的问题。七台锅炉运行参数的平均值为:实际热负荷/额定热负荷为40.56％,热效率为     

A CFD Study on the Effect of Shrinking Box Size on Cooling Airflows in Compact Electronic Equipment—The Case of Portable Projection Display Equipment

This work is concerned with the thermal design of portable projection display equipment (i.e., a portable projector). The portable projector is being made smaller and lighter to better serve the carrier, while its luminance is enhanced to benefit the viewer. The confluence of these demands increases the thermal loading on the projector. The design of cooling airflow path is becoming evermore important; however, the complex internal organization of the projector hampers an attempt to conduct flow and heat transfer analysis. A particularly important issue for the projector designer is to predict the effect of shrinking box size of the next generation product on cooling airflow. This paper describes a way to foresee the effects of reducing the key geometric dimensions of the projector on the distribution of airflow. The analysis is conducted using a computational fluid dynamics (CFD) code. CFD results are obtained on sampled points in the parameter domain and used to find the effects of various geometric parameters on the airflow rates. The sampling and screening of CFD results follows the Taguchi method (or the method of experimental design). The most influential parameters for the total airflow rate and the airflow rate over the electronics board are identified. This conclusion, however, is only an illustration of how the CFD analysis can assist the equipment designer in planning the next generation product. The methodology reported here can be applied in the plan and design of other electronic equipment that have similarly complex internal organizations in shrinking system boxes.     

Strive Toward A Green,Environment friendly and Resource Conserving City—— Shanghai Tobacco (Group) Corp purchased 600 MWh green electricity with the term of two years

Shanghai Tobacco (Group ) Corp was or- ganizationreformed and establishedfrom o- riginalShanghai Tobacco Company and its subsidiarycompany in 1993. Itpossesses high-classmod eratecigaretteindustryand its assorted enterprisesof tobacco storage and transpor…     

Like to Be A ″Green″ Sponsor——TCP (Shanghai) TianCanBao Springlamp Electric Co., Ltd purchased 60 MWh green electricity with term of one year

TCP (Shanghai) TianCanBao Springlamp Electric Co .,Ltd.islarge-scaletransnationaclorporationinlight source fieldestablishedby Shanghainess inAmerica.At the end oflastcentury, TCP establishedmodern pro- duction base with more than 100 thousands square mete…     

Advances in recombinant battery separator mat (RBSM) separators for lead-acid batteries—a review

Microglass separators have been used in lead-acid batteries for more than 20 years with excellent results. This type of separator (known as recombinant battery separator mat (RBSM)) has allowed valve-regulated lead-acid (VRLA) battery technology to become a commercial reality. When the concept of the VRLA battery was developed, the requirements of the RBSM separator were not fully known nor appreciated. In many cases, the direction charted for the separator has not been the most beneficial path to follow for separator performance and battery life. In some cases, such as the density of the separator media, experience has shown that the most correct path (low density) does not give rise to long battery life. As VRLA battery technology matures, greater pressure on cost and quality has arisen, especially with the proposed transition to 42 V automotive applications. This paper reviews some of the advances and changes in the RBSM separator made over the last 20 years, and provides some thoughts on future directions for this essential component of the VRLA battery.     

A hybrid power plant (Solar–Wind–Hydrogen) model based in artificial intelligence for a remote-housing application in Mexico

World fossil fuel reserve is expected to be exhausted in coming few decades. Therefore, the decentralization of energy production requires the design and integration of different energy sources and conversion technologies to meet the power demand for single remote housing applications in a sustainable way under various weather conditions. This work focuses on the integration of photovoltaic (PV) system, micro-wind turbine (WT), Polymeric Exchange Membrane Fuel Cell (PEM-FC) stack and PEM water electrolyzer (PEM-WE), for a sustained power generation system (2.5 kW). The main contribution of this work is the hybridization of alternate energy sources with the hydrogen conversion systems using mid-term and short-term storage models based in artificial intelligence techniques built from experimental data (measurements obtained from the site of interest), this models allow to obtain better accuracy in performance prediction (PV_MSE = 8.4%, PEM-FC_MSE = 2.4%, PEM-WE_MSE = 1.96%, GSR_MSE = 7.9%, WT_MSE = 14%) with a practical design and dynamic under intelligent control strategies to build an autonomous system.     

Light and stable LinB14(n=1–5) clusters for high capacity hydrogen storage at room temperature: A DFT study

In this article, we have explored the hydrogen (H₂) storage capacity of the Li doped B clusters Li_nB₁₄(n = 1–5) using density functional theory (DFT). The geometrical and Bader's topological parameters indicate that the clusters adsorb H₂ in the molecular form. The Li atom polarises the H₂ molecules for their effective adsorption on the clusters. The Li_nB₁₄ (n = 1–5) clusters are found to be stable even after H₂ adsorption at room temperature. The average adsorption energy is found to be in the range of 0.12–0.14 eV/H₂. Among the various clusters, the Li₅B₁₄ shows maximum H₂ storage capacity (13.89 wt%) at room temperature. The ADMP simulation reveals that within few femtoseconds (fs), the H₂ molecules begin to move away from the clusters and within 400 fs most of the H₂ molecules moved away from the clusters.     

Hydrogen storage in magnesium decorated boron clusters (Mg2Bn,n = 4–14): A density functional theory study

The capacity of hydrogen adsorption of magnesium (Mg) decorated small boron (B) clusters (Mg₂B_n; n = 4–14) was studied using density functional theory (DFT). The calculated results indicate that H₂ adsorbed in the molecular form. The Bader's topological analysis indicates the presence of closed shell type interaction between clusters and H₂ molecules. The clusters are stable even after the adsorption of H₂ molecules. The average energy of H₂ adsorption is calculated to be in the range of 0.13–0.22 eV/H₂. The Mg₂B₆ cluster shows maximum H₂ adsorption (8.10 wt%) at ambient temperature and pressure. Further, we have performed molecular dynamic (MD) simulation at room temperature for each cluster to understand adsorption and desorption of H₂ molecules with time. The MD simulation revealed that most of the adsorbed H₂ molecules moved away from the clusters within 200 fs. However, one H₂ molecule remains attached with the Mg₂B₁₁ cluster even after 200 fs.