Combined cooling, heating and power: A review

Combined cooling, heating and power (CCHP) systems, including various technologies, provide an alternative for the world to meet and solve energy-related problems, such as energy shortages, energy supply security, emission control, the economy and conservation of energy, etc. In the first part of this paper, the definition and benefits of CCHP systems are clarified; then the characteristics of CCHP technologies—especially technical performances—are presented, as well as the status of utilization and developments. In the third part, diverse CCHP configurations of existing technologies are presented, particularly four typical systems of various size ranges. The worldwide status quo of CCHP development is briefly introduced by dividing the world into four main sections: the US, Europe, Asia and the Pacific and rest of the world. It is concluded that, within decades, promising CCHP technologies can flourish with the cooperative efforts of governments, energy-related enterprises and professional associations.     

火电厂NOX污染排放控制方法探讨

NOx的排放控制将是火电厂未来环境保护的重要任务，减少NOx排放的一些方法。     

大庆油田射孔完井过程中的油层保护技术

室内实验研究可知,射孔完井过程中油层的伤害主要是射孔压实带和射孔液的伤害。射孔压实带伤害程度较大,渗透率伤害率高达60.0%～80.0%;射孔液伤害程度相对较小,室内实验岩心渗透率伤害率在30%～36%之间。综述了大庆油田目前射孔完井过程中的油层技术,主要有负压射孔和采用射孔保护液,取得了较好的油层保护效果,采用负压射孔技术单井产能提高幅度20%～30%,采用优质射孔液单井产能提高幅度为20%左右。     

Optimum thermoeconomic and thermodynamic performance characteristics of an irreversible three-heat-source heat pump

The coefficient of performance and specific heating load of an irreversible three-heat-source heat pump are given by using a general cycle model affected by the finite-rate heat transfer, heat leak and internal irreversibility of the cyclic working fluid. The heat pumping load divided by the total cost per unit time is taken as a new objective function and used to investigate the performance of the heat pump. The thermoeconomic and thermodynamic performance characteristics of the heat pump are discussed in detail. Some important performance parameters such as the thermoeconomic objective function and coefficient of performance are optimized. The optimally operating regions of the heat pump and the bounds of several performance parameters are determined. Finally, it is pointed out that the Carnot heat pump may be taken as a special case of a three-heat-source heat pump and consequently its optimal performance can be directly derived from the results obtained here.     

An integrated system framework for fuel cell-based distributed green energy applications

The environmental pollution and diminishing conventional fuel sources and global warming problems make it more attractive for considering renewables as alternative energy sources, such as solar, wind and micro hydro, etc. Recent advances in hydrogen and fuel cell technologies further facilitate these energy options to supply electrical power to various communities. Hydrogen fuel cell systems coupled with renewable energy sources stand out as a promising solution. This paper presents an integrated system framework for fuel cell-based distributed energy applications. Five components are included in this framework: a physical energy system application, a virtual simulation model, a distributed coordination and control, a human system interface and a database. The integrated system framework provides a means to optimize system design, evaluate its performance and balance supplies and demands in a hydrogen assisted renewable energy application. It can either be applied to a distributed energy node that fulfills a local energy demand or to an energy-network that coordinates distributed energy nodes in a region, such as a hydrogen highway. The proposed system framework has been applied in the first phase of our multi-phases project to investigate and analyze the feasibility and suitability of hydrogen fuel assisted renewable power for a remote community. Through integration with an available renewable energy profile database, the developed system efficiently assists in selecting, integrating, and evaluating different system configurations and various operational scenarios at the application site. The simulation results provide a solid basis for the next phase of our demonstration projects.     

玉米秸秆干燥特性的试验研究

为获取玉米秸秆干燥机设计的基础数据，对我国北方产的玉米秸秆进行工业分析、热重分析及等温干燥特性试验研究，得到了玉米秸秆水分、挥发分的相对含量、不同升温速率下的失重曲线以及各种温度下不同含水量的失重曲线。实验结果表明：玉米秸秆干燥过程中的湿球温度应控制在150℃以下，干燥时间为20～30min。     

基于气体流动计算的摩托车净化系统设计

排气管内的流场和温度场分布对排气净化系统的性能具有很大的影响,因此弄清楚摩托车排气 管内流场的分布情况十分必要。本文利用FLUENT软件对152QMI摩托车排气管内的流场进行模拟计 算。根据得到的流场分布合理布置催化转化器和二次空气喷射的位置,从而获得比较好的催化净化效 果以降低有害物的排放。     

通用变频器控制系统的探讨

本文分析了目前流行的通用变频器的两种控制方式,并对矢量控制和直接转矩控制方案作了比较和探讨,最后给出实现高性能通用变频器的途径.     

Hygrothermomechanical Effects on Laminated Composite Plates in Terms of a Higher-Order Global-Local Model

Results analytical or numerical on transverse shear stresses of laminated composite plates subjected to hygrothermomechanical effects are scarce in literature. To fill this gap, a higher-order global-local model (HGLM) satisfying the continuity conditions of transverse shear stresses at interfaces is proposed. Based on stress continuity condition between layers, the number of variables in the proposed model is independent of the number of layers of the laminate. Applying Navier's technique to equilibrium equations obtained using the principle of minimum potential energy, analytical solution of the model HGLM is derived for simply supported composite plates. Comparing the results from available three-dimensional elasticity theory and those computed from the first-order and the higher-order models, it is found that the proposed model can produce promising transverse shear stresses directly from constitutive equations without any smoothing technique. The effects of material properties, aspect ratio, side-to-thickness ratio, stacking sequence and thermal expansion coefficients on the hygrothermomechanical response have also been studied.     

气保药芯焊丝用于低温钢压力容器制造的性能研究

焊接是石油化工低温钢压力容器制造的重要工序,随着石油化工装置规模不断扩大,对低温钢压力容器的焊接质量和焊接效率提出了越来越高的要求。气保药芯焊接材料因其高质量、高效率、易于同母材匹配等优点而应用广泛,但在低温钢压力容器制造领域还应用较少。以典型的HOBART XL550气保药芯焊丝为例,根据低温钢压力容器制造的焊接要求,进行了熔敷金属扩散氢检测试验、焊丝吸潮性试验、热处理性能测试、CTOD测试。测试结果表明:XL550气保药芯焊丝最高扩散氢含量均小于4m L/100g熔敷金属,满足低氢焊接要求;焊态和热处理状态下的强度、硬度和冲击韧性也均满足压力容器的焊接要求;具有良好的止裂性能。在性能测试的基础上进行的现场对接焊试验结果表明,XL550气保药芯焊丝满足低温钢压力容器低氢焊接和热处理前后机械性能稳定的要求。