Performance Evaluation of Solar Chimney Draft: Application to Ventilation

Ventilation is one of the factors contributing to energy consumption in buildings and food preservation. The solar chimney proves to be an alternative for reducing conventional energy consumption. Thus, in this study, the performance of a solar chimney with two active faces for thermally drawing air from a chamber for preserving agri-food products was evaluated. These performances were experimentally assessed through data measurements: temperatures and velocities within the chimney, and their analysis using Excel and MATLAB. The obtained results were compared with those from literature to verify their validity. From this study, it is found that the maximum temperature at the chimney outlet reaches 49.4˚C with an average value of 43.7˚C. Additionally, the heating evolution of the chimney air presents four (04) identical phases in pairs, reflecting the chimney’s operation throughout day. The temperature difference between the outlet and inlet of the chimney reaches a maximum of 17˚C with an average of 12.6˚C. Regarding airflow, the maximum air velocity at the chimney outlet is 0.8 m/s, and the average velocities have consistently been greater than or equal to 0.46 m/s. Thus, it can be concluded that the solar chimney is capable of providing ventilation for the preservation chamber through thermal draft.

SOLID-LIQUID SUSPENSION SYSTEM IN AGITATED TANK WITH DRAFT TUBE

Solid-liquid suspension in an agitated tank with a draft tube was investigated witha newly developed infrared turbidimeter for measuring solid concentration.The diameter of theflared inlet transition tube and the distance from the inlet to the tank bottom are two importantparameters for draft tube design The NAX-4 impeller,developed in this study,is characterized byits high flow efficiency and low power consumption.Some modifications are made to the Bald′smodel by considering the effects of solid concentration and fluid viscosity on the critical speed forcomplete off-bottom suspension.The modified equation fits the experimental data satisfactority andcan be used in scale-up

A review on design and testing methodologies of modern freight train draft gear system

Rolling stock connection systems are key to running longer and heavier trains as they provide both the connections of vehicles and the damping,providing the longitudinal suspension of the train.This paper focuses on the evolution of both connection and stiffness damping systems.Focus is on freight rolling stock,but passenger draw gears are also examined.It was found that connection systems have evolved from the buff and chain system used in the pioneer railways of the 1800s to the modern auto-coupler connection systems that are in-service worldwide today.Refined versions of the buff and chain coupling are,however,still in use in the EU,UK,South America and India.A wide range of auto-coupler systems are currently utilised,but the AAR coupler(Janney coupler)remains the most popular.A further variation that persists is the SA3 coupler(improved Wilson coupler)which is an alternative auto-coupler design used mainly throughout the former Soviet Union.Restricting the review to auto-coupler systems allowed the paper to focus on draft gears which revealed polymer,polymer-friction,steel spring-friction,hydraulic draft gears and sliding sill cushioning systems.Along with the single compressive draft gear units balanced and floating plate configurations are also presented.Typical draft gear acceptance standards are presented along with modelling that was included to aid in presentation of the functional characteristics of draft gears.

Study of a New Drafting System of Rubbed Roving Frame

This paper puts forward a new drafting system of the rubbed roving frame, which consists of a nine-link gear, two slipping gears. It has brought forward a new design method of the nine-link gear and the slipping gears, and set up approximate formulas for modification coefficients of gears for the first time. And the principles of transmitting rate designing for the system are given. The calculating results demonstrate that the new design method satisfies the demands of processing technology. This mechanism has been used successfully in the kind of rubbed roving frame.

Determination of Parameters Affecting the Estimation of Iceberg Draft

Recent offshore oil and gas loading facilities developed in the Arctic area have led to a considerable awareness of the iceberg draft approximation, where deep keel icebergs may gouge the ocean floor, and these submarine infrastructures would be damaged in the shallower waters. Developing reliable solutions to estimate the iceberg draft requires a profound understanding of the problem’s dominant parameters. As such, the dimensionless groups of the parameters affecting the iceberg draft estimation were determined for the first time in the present study. Using the dimensionless groups recognized and the linear regression(LR) analysis, nine LR models(i.e., LR 1 to LR 9) were developed and then validated using a comprehensive dataset, which has been constructed in this study. A sensitivity analysis distinguished the premium LR models and important dimensionless groups. The best LR model, as a function of all dimensionless parameters, was able to estimate the iceberg draft with the highest level of precision and correlation along with the lowest degree of complexity. The ratio of iceberg length to iceberg height as the “iceberg length ratio” and the ratio of iceberg width to iceberg height as the “iceberg width ratio” was detected as the important dimensionless groups in the estimation of the iceberg draft. An uncertainty analysis demonstrated that the best LR model was biased towards underestimating the iceberg drafts. The premium LR model outperformed the previous empirical models.Ultimately, a set of LR-based relationships were derived for estimating the iceberg drafts for practical engineering applications, e.g., the early stages of the iceberg management projects.

Experimental Study on the Resistance and Splash Performances of Water Collecting Devices for Mechanical Draft Cooling Towers

In recent years,water collecting systems,with the associated advantages of energy saving and noise reduction,have become the foundation for the development of a scheme to optimize the structure of cooling towers.To explore the feasibility of this approach for mechanical draft cooling towers,a small-scale experimental device has been built to study the resistance and splash performances of three U-type water collecting devices(WCDs)for different water flow rates and wind speeds.The experimental results show that within the considered ranges of wind speed and water flow rate,the pressure drop of the different WCDs can vary significantly.The resistance and local splash performances can also be remarkably different.Some recommendations about the most suitable system are provided.Moreover,a regression analysis of the experimental data is conducted,and the resulting fitting formulas for resistance and splash performance of WCD are reported.

Capacity Building Needs for Manual and Computer Assisted Teaching of Pattern Drafting for Entrepreneurship in Tertiary Institutions in Nigeria

This study investigated the capacity building needs for manual and computer assisted teaching of pattern drafting for entrepreneurship in tertiary institutions in Nigeria.The study was conducted and guided by two research questions and two hypotheses.This study adopted an ex-post facto research design.The population for the study consisted of 131 Home Economics lecturers from the Universities,Polytechnic,and Colleges of Education in South East Nigeria.The entire population was studied because of its manageable size,hence there was no sampling.The results of this study showed that the Home Economics lecturers are competent in drafting patterns using manual method.Technical skills required for lecturers of Home Economics to advance from manual to computer-assisted teaching of pattern drafting were identified.They include ability to grade patterns,ability to use software packages,and ability to discuss procedures of pattern drafting among others.Based on the findings,it was recommended among others that computer assisted teaching of pattern drafting should be incorporated and applied by Home Economics lecturers to ensure that students acquire technical skills that will enable them to enter into entrepreneurship.

X─Window应用程序与I─DEAS Drafting的集成技术

对软件二次开发中应用程序与绘图软件的集成技术进行了探讨；着重介绍了X─Window应用程序与I─DEASDrafting绘图软件的集成方法，通过此方法，可为用户提供一个集成的绘图环境．

基于UG/Drafting的国标化工程辅助制图软件

介绍了基于UG/Drafting的国标化工程辅助制图软件(InteCAD),描述了系统的设计思想和主要功能。从使用过程中来看,该软件能够满足工程制图的实际需求。

Drafting实现机械制图附助标注

本文基于I—DEAS Drafting进行了二次开发,实现了机械制图中的附助标注。

在UG/Drafting中实现格式刷功能

介绍了利用二次开发技术在UG/Drafting中实现格式刷功能的原理和具体方法,并利用配置文件的方法实现了有选择性的格式刷功能,编制了相应的程序,提高了UG软件的易用性,具有较强的实用价值。

轴流式引风机失速及预防研究

目前,轴流式引风机在电力领域发挥着重要作用,其稳定运行对电厂的生产效率和安全性有着直接影响。不过在实际运行过程中,轴流式引风机可能会出现失速现象,导致风压、风量大幅下降,甚至引发生产停滞,给企业带来直接的经济损失。此外,失速可能对风机自身造成损伤,缩短其使用寿命,并带来安全隐患。因此,深入研究和理解轴流式引风机失速现象,掌握其发生机理和预防措施,对于保障工业生产的顺利进行和人员安全具有重要意义。基于此,对轴流式引风机的基本结构和运行原理进行简要分析,并对其失速原因和机理进行阐述,进而提出具体预防与控制措施,以期为相关领域的研究和实践提供参考。

基于UG/Drafting的公差标注系统开发研究

针对当前UG/Drafting平台公差标注的薄弱环节,提出了公差标注的系统架构,并介绍了框架设计的基本内容;最后利用Visual C++6.0编译器,以UG/OPEN为工具开发了二维公差标注系统。开发的系统可满足工程制图的实际需要,并对UG其他方面的二次开发有一定指导意义。

Expert consensus on standardized diagnosis and treatment for heat stroke(draft)

Overview Heats stroke(HS)is severe sunstroke caused by a rapid increase in one’s core temperature in excess of 40°C from exposure to a hot and humid environment.HS is accompanied by serious clinical syndromes that damage multiple organ systems.h ese syndromes include burning skin and impaired awareness,such as delir ium,conv ul sions,and loss of consciousness.Exertional heat stroke(EHS)is caused by a rapid increase in one’s core temperature in excess of 40°C from high

Draft effect on wave action with a semi-infinite elastic plate

A method for analyzing reflection and transmission of ocean waves from a semi-infinlte elastic plate with a draft is developed. The relation of energy conservation for plates with three different edge conditions （ free, simply supported and built-in） is also derived. It is found that the present method satisfies the energy relation very well. The effects of draft on wave reflection and transmission coefficients as well as on the vertical vibration of the plates are examined through numerical tests. It is demonstrated that the zero draft assumption works well for low wave frequencies, but the effect of plate draft becomes significant for high wave frequencies.

Full scale experimental study of a small natural draft dry cooling tower for concentrating solar thermal power plant

Concentrating solar thermal power system can provide low carbon,renewable energy resources in countries or regions with strong solar irradiation.For this kind of power plant which is likely to be located in the arid area,natural draft dry cooling tower is a promising choice.To develop the experimental studies on small cooling tower,a 20 m high natural draft dry cooling tower with fully instrumented measurement system was established by the Queensland Geothermal Energy Centre of Excellence.The performance of this cooling tower was measured with the constant heat input of 600 kW and 840 kW and with ambient temperature ranging from 20 ℃ to 32 ℃.The cooling tower numerical model was refined and validated with the experimental data.The model of 1 MW concentrating solar thermal supercritical CO2 power cycle was developed and integrated with the cooling tower model.The influences of changing ambient temperature and the performance of the cooling tower on efficiency of the power system were simulated.The differences of the mechanism of the ambient temperature effect on Rankine cycle and supercritical CO2 Brayton cycle were analysed and discussed.

CFD-Based Method of Determining Form Factor k for Different Ship Types and Different Drafts

The value of form factor k at different drafts is important in predicting full-scale total resistance and speed for different types of ships. In the ITTC community, most organizations predict form factor k using a low-speed model test. However, this method is problematic for ships with bulbous bows and transom. In this article, a Computational Fluid Dynamics(CFD)-based method is introduced to obtain k for different type of ships at different drafts, and a comparison is made between the CFD method and the model test. The results show that the CFD method produces reasonable k values. A grid generating method and turbulence model are briefly discussed in the context of obtaining a consistent k using CFD.

Oblique wave scattering by a semi-infinite elastic plate with finite draft floating on a step topography

On the basis of a potential theory and Euler-Bernoulli beam theory, an analytical solution for oblique wave scattering by a semi-infinite elastic plate with finite draft floating on a step topography is developed using matched eigenfunction expansions. Different from previous studies, the effects of a wave incident angle, a plate draft, three different plate edge conditions （free, simply supported and built-in） and a sea-bottom topography are all taken into account. Moreover, the plate edge conditions are directly incorporated into linear algebraic equations for determining unknown expansion coefficients in velocity potentials, which leads to a simple and efficient solving procedure. Numerical results show that the convergence of the present solution is good, and an energy conservation relation is well satisfied. Also, the present predictions are in good agreement with known results for special cases. The effects of the wave incident angle, the plate draft, the plate edge conditions and the sea-bottom topography on various hydrodynamic quantities are analyzed. Some useful results are presented for engineering designs.

NUMERICAL INVESTIGATION OF THE ADVERSE EFFECT OF WIND ON THE HEAT TRANSFER PERFORMANCE OF TWO NATURAL DRAFT COOLING TOWERS IN TANDEM ARRANGEMENT

This article reports the findings on the adverse effect of the crosswind on the performance of natural draft cooling towers through numerical computation with the k-epsilon eddy-viscosity turbulence model. It is observed here that the cause of the adverse effect of the crosswind on the cooling towers call be attributed to the around flow effect which destroys the radial inflow into the cooling towers when the wind is absent. Hence, a significant deterioration in the heat transfer from the heat exchangers at lateral sides occurs.

Draft Consensus Building in Hall for Workshop of Meta-Synthetic Engineering

This paper discusses that there are two sorts of group consensus in Hall for Workshop of Meta-synthetic Engineering： draft consensus and decisive consensus, which are respectively formed in the two synchronous stages in the process of ＂synchronous stages 1- asynchronous stages- synchronous stages 2＂, and focuses on the concept of draft consensus. Then proposes a draft consensus building model and its solution method called Consensus Building Graph, by which claim concern value, claim support value, claim authority value and claim consensus value can be calculated real time for reaching a consensus, and designs a computer aided consensus building system called Internet based Group Discussion Environment. The model follows the methodology of meta-synthesis from qualitative to quantitative analysis in which computers and humans are combined to solve complex problems.