射流管在气力输送中的应用

对物料气力输送的各种供料方式的性能、特点和使用场合进行了比较 ,重点讨论了传统文丘里供料器实际应用中存在的问题 ,介绍了几种国内外新型的文丘里供料器结构及其特点和用途。指出采用组合式供料器 ,即将文丘里供料器与机械旋转式连续供料器进行组合使用 ,可以同时改善它们两者单独使用时存在的问题。文中介绍了LAVAL管密相输送气量控制方面的应用 ,指出LAVAL管在气力输送中主要起稳定空气流量和压力的作用 ,使输送过程稳定、均匀 ,并简要介绍了气力输送系统的设计方法和步骤     

蒸汽喷射式热泵供热系统热力学分析

探讨了从造纸厂能量衡算的角度来分析蒸汽喷射式热泵供热系统的节能潜力,通过放大计算控制体,将锅炉纳入热力计算范围,计算纸机干燥部耗汽量和锅炉燃煤量来对比分析能量消耗,得出蒸汽喷射式热泵供热系统节能潜力的大概范围。提出蒸汽喷射式热泵用于供热系统的最主要作用是它显著地增大烘缸排水压差,减小烘缸传热热阻。研究蒸汽喷射式热泵及其系统的合理设计与利用。     

喷射器内气-液两相流流型及其转换特性的研究

利用平面激光诱导荧光(Planar Laser Induced Fluorescence,PLIF)技术,分析上喷式喷射器内气液两相流的流型及流型转换的特性.结果表明,在喷射器内气液两相首先形成喷射流,随着两相相互作用和动量传递,射流瓦解,气液两相随着气液比的不断增大分别形成泡状流、雾状流和块状流.根据实验结果绘制了喷射器上部射流瓦解后的气液两相流流型图.通过分析流型影响因素和流体力学特点,提出了流型转换的无因次关系式,并确定了各流型转换的具体表达式.     

多喷嘴汽-液两相喷射器的工作特性研究

对以湿蒸汽为工作流体的多喷嘴汽–液喷射器机制进行研究,利用质量、能量及动量守恒方程建立了喷射器工作特性一维理论模型。模型求解过程中,采用两相临界流均相平衡模型计算单喷射蒸汽喷嘴的临界流速,并利用多喷射速度系数对其修正,得到多喷射蒸汽喷嘴的出口速度;综合考虑Cattadori的壁面力和Howard的喉部压损理论对流动的影响来确定混合室阻力。为验证模型的正确性,设计以湿蒸汽为工作蒸汽的实验台,并采用多喷嘴喷射器作为实验元件。研究结果表明:容积喷射系数随压力比的增大而减小,且增大喷射器的截面比可使容积喷射系数增加,但缩小了喷射器的工作范围;容积喷射系数随蒸汽干度的增大和过冷水温度的升高而减小。理论计算结果与实验值基本相符。     

液化气脱硫醇尾气引入催化再生器燃烧的治理措施

中海石油宁波大榭石化有限公司2.2 Mt/a深度催化裂解(DCC)联合装置配套120 t/h液化气脱硫醇装置,针对液化气脱硫醇碱液再生尾气中含有氧气、烃类和二硫化物,导致环境污染、设备腐蚀和堵塞、安全隐患等生产难题,该公司将脱硫醇尾气引入DCC装置,采取催化再生器燃烧的治理措施.结果表明:在高温富氧的条件下使脱硫醇尾气...     

Performance analysis of cogeneration systems based on micro gas turbine (MGT), organic Rankine cycle and ejector refrigeration cycle

In this paper, the operation performance of three novel kinds of cogeneration systems under design and off-design condition was investigated. The systems are MGT (micro gas turbine) + ORC (organic Rankine cycle) for electricity demand, MGT+ ERC (ejector refrigeration cycle) for electricity and cooling demand, and MGT+ ORC+ ERC for electricity and cooling demand. The effect of 5 different working fluids on cogeneration systems was studied. The results show that under the design condition, when using R600 in the bottoming cycle, the MGT+ ORC system has the lowest total output of 117.1 kW with a thermal efficiency of 0.334, and the MGT+ ERC system has the largest total output of 142.6 kW with a thermal efficiency of 0.408. For the MGT+ ORC+ ERC system, the total output is between the other two systems, which is 129.3 kW with a thermal efficiency of 0.370. For the effect of different working fluids, R123 is the most suitable working fluid for MGT+ ORC with the maximum electricity output power and R600 is the most suitable working fluid for MGT+ ERC with the maximum cooling capacity, while both R600 and R123 can make MGT+ ORC+ ERC achieve a good comprehensive performance of refrigeration and electricity. The thermal efficiency of three cogeneration systems can be effectively improved under off-design condition because the bottoming cycle can compensate for the power decrease of MGT. The results obtained in this paper can provide a reference for the design and operation of the cogeneration system for distributed energy systems (DES).     

Performance analysis of a supersonic ejector cycle working with R245fa

A supersonic ejector chiller for industrial use is currently being developed and tested as part of a project cooperation between Frigel s.p.a and DIEF (Department of Industrial Engineering, University of Florence). The refrigerator was built following a “ready to market” setup criterion and is intended for applications on the industrial refrigeration market or in air conditioning. The plant has a nominal cooling power of 40 kW and is powered by low temperature heat (from 90 up to 100 °C). The ejector is equipped with a movable primary nozzle and 9 static pressure probes along the mixing chamber/diffuser duct. The working fluid is R245fa. An extensive numerical campaign was performed to analyze the internal dynamics of the ejector. All the simulations were carried out by accounting for the real gas properties of the refrigerant. Comparison with experimental data resulted in close agreement both in terms of global and local parameters. Analyses showed that in order to achieve an accurate matching with the experimental data, it is necessary to correctly account for the surface roughness of the ejector. This is especially true for off-design operating conditions.     

跨临界CO2引射制冷系统控制性能研究

本文建立了两种控制器（单通道最优控制器（SCOC）和多变量线性二次高斯控制器（LQG））以改善跨临界CO2引射制冷系统的运行效率。首先建立了SCOC,通过在线调节喷嘴喉部面积,搜索系统最优的气冷器压力;其次针对SCOC作用下制冷量不可控的缺点,设计了LQG以实现系统制冷量可调。将两种控制器分别应用于实验系统中,结果表明：SCOC能够驱使系统不断接近给系统的最优气冷器压力,给定工况下获得最大制热系数COPh为3.15,但导致系统制冷量的不可控。在LQG的作用下,气冷器压力、系统制冷量得到独立控制,显示了很好的参数跟随性,然而LQG无法保证系统的稳态运行效率。研究指出两种控制器各有优缺点,若实现满足系统负荷需求的同时保持系统最高的运行效率,需要设计结合两种算法特点的新型控制器。     

喷射器极限工况特性实验研究

喷射器作为热驱动喷射式制冷系统的核心部件,其性能会影响整个制冷系统的运行效率。极限工况是指喷射器从可以工作状态到不能工作状态的极端工况,对该工况下喷射器的特性研究具有重要意义。本文自行设计并搭建了以R134a为制冷剂的喷射式制冷系统极限工况的实验装置,分别对引射流体质量流量为零的极限工况下不同喷射器工作流体压力及喷射器出口背压对缩放喷嘴出口背压的影响规律进行了实验研究。结果表明:极限工况下,喷嘴出口背压同时受工作流体压力和喷射器出口背压的影响,随工作流体压力升高而降低,随喷射器出口背压升高而升高。同时,得到该喷射器在工作流体压力为1.5~3.2MPa,且喷射器出口背压在0.66~0.96 MPa范围内的最低引射流体压力,为工程应用提供参考。     

Hydrodynamics of liquid-liquid dispersion in ejectors and vertical two phase flow

Mixing of two immiscible liquids can be conveniently achieved in a liquid-jet ejector system which utilizes the kinetic energy of a liquid-jet to simultaneously aspirate and interdisperse the immiscible phases. In such a dispersion process energy dissipation occurs due to friction on the walls of the ejector throat and divergent diffuser, as well as due to mixing and interdispersion of the two phases. The paper deals with the analysis and quantification of these different energy losses. Measurements have also been reported on pressure drop and holdup of two phase liquid-liquid flow in a vertical column fitted to the ejector system. Correlations have been developed for predicting the irreversible pressure drop (in terms of a two-phase friction factor) and the holdup on the basis of the physical and dynamic variables of the system. A term ‘degree of mixing’, defined as the ratio of the actual holdup fraction to the homogeneous holdup fraction, has been used to estimate the extent of mixing.