Air interaction around outdoor air-cooled condensers

In order to increase cooling or heating efficiency,a porous computational fluid dynamics（CFD）model is employed to predict the thermo-fluid status and optimize the placement of outdoor units.A full scale model is established to validate the accuracy of CFD simulation in terms of velocity and temperature distributions.The comparison between the measurement and the simulation shows a good agreement.By evaluating the condensers＇ sucked air temperature with CFD for three units installed in a row,it is found that the minimum separation distance among neighboring units is 0.2 m;a vertical wall should be apart from the unit line by at least 0.8 m;and large different operating pressures among units do not impact the flow rate and the heat transfer of the other units meaningfully.

Thermodynamic Simulation of CCP in Air-Cooled Heat Pump Unit with HFCs and CO₂Trans-Critical

The exergy analysis and finite time thermodynamic methods had been employed to analyze the compound condensation process (CCP). It was based on the air-cooling heat pump unit. The cooling capacity of the chiller unit is about 1 kW, and the work refrigerant is R22/R407C/R410A/CO2. The MATLAB/SIMULINK software was employed to build the simulation model. The thermodynamic simulation model is significant for the optimization of parameters of the unit, such as condensation and evaporation temperature and mass flow of the sanitary hot water and size of hot water storage tank. The COP of the CCP of R410A system is about 3% - 5% higher than the CCP of the R22 system, while CCP of the R407C system is a little lower than the CCP of R22 system. And the CCP of CO2 trans-critical system has advantage in the hot supply mode. The simulation method provided a theoretical reference for developing the production of CCP with substitute refrigerant R407C/R410A/CO2.

The Experimental Investigation of Recirculation of Air-Cooled System for a Large Power Plant

The paper introduces thermal buoyancy effects to experimental investigation of wind tunnel simulation on direct air-cooled condenser for a large power plant. In order to get thermal flow field of air-cooled tower, PIV experiments are carried out and recirculation ratio of each condition is calculated. Results show that the thermal flow field of the cooling tower has great influence on the recirculation under the cooling tower. Ameliorating the thermal flow field of the cooling tower can reduce the recirculation under the cooling tower and improve the efficiency of air-cooled condenser also.

Influence of thermal flow field of cooling tower on recirculation ratio of a direct air-cooled system for a power plant

In order to get thermal flow field of direct air-cooled system,the hot water was supplied to the model of direct air-cooled condenser(ACC). The particle image velocimetery (PIV) experiments were carried out to get thermal flow field of a ACC under different conditions in low velocity wind tunnel,at the same time,the recirculation ratio at cooling tower was measured,so the relationship between flow field characteristics and recirculation ratio of cooling tower can be discussed. From the results we can see that the flow field configuration around cooling tower has great effects on average recirculation ratio under cooling tower. The eddy formed around cooling tower is a key reason that recirculation produces. The eddy intensity relates to velocity magnitude and direction angle,and the configuration of eddy lies on the geometry size of cooling tower. So changing the flow field configuration around cooling tower reasonably can decrease recirculation ratio under cooling tower,and heat dispel effect of ACC can also be improved.

自然通风湿式冷却塔节水方案的数值研究

为降低自然通风湿式冷却塔的耗水量,本文采用一种可用于回收其蒸发损失的空气冷凝器结构,并通过数值模拟方法对其节水特性展开研究。首先基于空气运动控制方程和水蒸气冷凝模型,建立了用于分析空气冷凝器节水特性的数学模型,其次分析了冷却空气流速、空气冷凝器的结构尺寸和材质等因素对该冷凝器节水特性的影响。研究结果表明:空气冷凝器的单位面积节水量随着冷却空气流速以及冷凝器宽度的增大而增大,但随着冷凝器长度和高度的增大而减小;空气冷凝器的材质和壁厚对其单位面积节水量没有显著影响,空气冷凝器可采用重量轻和成本低的薄壁PVC来加工制造。

钢铁企业双压蒸汽发电机组供热改造的探讨

随着钢铁企业产品结构改革和高质量发展的需要,企业蒸汽需求与产蒸汽的能力出现矛盾,尤其冬季采暖季期间更突出,企业为满足蒸汽需求进行发电机组的供热改造势在必行。针对钢铁企业发电机组将纯凝机组改造成纯凝加背压机组的供热改造方案,结合实施过程中出现的问题,提出相应优化解决方案。

吸收式溴化锂机组回收蒸汽凝液余热制冷技术改造分析

介绍了余热回收溴化锂制冷机组的工作原理,针对鑫润公司60万t/a草酸技改乙二醇装置存在的1.0 MPa(G)蒸汽冷凝液大量直排、所含余热未进行利用的问题,进行了技术改造,即在乙二醇冷冻站新增吸收式溴化锂制冷机组系统,利用凝液余热制取冷冻水。改造后,热能浪费问题得到了有效解决,每年可节约电能2740.53万kW·h,相当于节约标准煤3368.11 t、减少CO_(2)排放量15629.24 t。

Feasibility of condensate water recycle of split air handling unit in Chinese University buildings

Recycling the condensate water of the air conditioner could be explored as an alternative water source to con-tribute to building the green campus.This paper explored the condensate water production through actual mea-surement based on a split air handling unit(SAHU)in a university building.Then,the statistical analysis was used to analyze the recycling feasibility and the impact factors of the condensate water production in 31 Chinese provincial capital cities to obtain the recycling potential map of the condensate water generated from a SAHU.Results showed that:(1)In the measurement,the amount of condensate water produced by a single split air conditioner was 1.6 kg from 12:40 to 13:40.Therefore,the daily output of condensate water of the air condi-tioner with the university operation schedule could reach 52.99 kg during the main air-conditioning season.(2)Among the 31 provincial capital cities in China,the largest condensate water outputs could be found in the Hot Summer and Warm Winter zone and the Hot Summer and Cold Winter zone,with an average monthly output of 1600 kg and 1100 kg,respectively.(3)Regression analysis showed that the dry-bulb temperature and dew point temperature of outdoor air had the highest positive and significant influence on condensate water production.The objective of this study is to provide theoretical guidance for the design and energy conservation evaluation of the feasibility of SAHU condensate water recycling in universities.

室外机防护格栅对空调夏季运行能效影响的实验研究

人们通常将注意力集中在空调设备的额定能效,却较少关注室外机安装方式对空调系统实际运行能效的影响。实际上,空调室外机的防护格栅形式在很大程度上会影响整个系统的能效。因此,对防护格栅的设计和安装进行有效改进,以降低空调的能耗,变得尤为重要。为了解决传统空调室外机防护格栅通风换气能力差的问题,设计了一种高效节能通风防护格栅,并通过实验验证了其在提升系统能效比和节能性方面的成效。结果显示,在夏季平均气温维持在35℃的条件下,相较于传统防护格栅,这种节能防护格栅能够将能耗降低33%,系统制冷能效比提高59%。实验表明,本文所设计的防护格栅对于改善凹槽式安装的空调室外机系统性能具备显著效果。

旁路蓄热对凝汽式机组调峰容量的影响

为研究熔盐蓄热技术对凝汽式机组调峰容量的影响,以660 MW超临界凝汽式机组为例,选择低熔点LMPS II熔盐为蓄热介质,将蓄热系统与汽轮机旁路系统相结合,构建3种旁路蓄热方案,应用EBSILON软件建立系统的仿真模型,研究凝汽式机组引入熔盐蓄热后调峰容量和调峰容量补偿的变化。结果表明:整机旁路蓄热方案可以使机组发电负荷率降得最低;在蓄热时长相同的条件下,低压旁路蓄热方案放热顶峰运行时间最长;以30%发电负荷率作为起始蓄热工况,旁路蓄热方案的调峰容量增加3.21%~6.42%;在蓄热起始工况发电负荷率较低时,机组的调峰容量补偿较大。

“双碳”背景下受端电网火电机组增加调相功能关键技术

随着新型电力系统推进建设,受端电网逐步形成了高比例可再生能源和高比例跨区直流接入的典型特征。在发生直流闭锁、换相失败等故障情况下,受端电网暂态电压支撑需求骤增。由于同步电源开机占比逐渐降低,动态无功资源缺口逐渐加大。静止无功补偿能力较弱,新建调相机成本较高,利用存量火电机组增加调相功能成为技术经济的最优选择。首先分析了“双高”型受端电网的暂态电压支撑需求和调相机的电压支撑机理,并对国内外火电机组增/改调相功能的案例进行了综述。在此基础上,基于河南鸭河口火电机组增加调相功能工程实践,提出了火电机组增加调相功能的关键技术,开辟了一条面向高比例可再生能源接入的受端电网电压暂态支撑能力和存量火电机组利用率提升的有效技术路径。

硫磺装置三级冷凝器管束腐蚀原因及对策

某炼油厂硫磺装置三级冷凝器冷凝器(E102)管束外、内壁均有腐蚀发生。通过对冷凝器器进行材质分析、金相检验及电镜分析后结合工艺流程综合判断。结果表明,E102管束有其外壁发生的腐蚀穿孔应该是由溶解氧腐蚀造成,管束内壁的腐蚀性质为管内过程气介质的腐蚀。

高速列车空调冷凝侧流阻特性及风量变化仿真研究

利用计算流体动力学(CFD)手段,对明线无会车运行状态下的某型动车组列车空调冷凝侧进行仿真研究。结果表明:车速对空调冷凝风量和表面流场有较大影响,在叠加外流场的条件下冷凝风量随车速的增大而减小;相同车速下不同安装位置的空调机组受局部涡流区的干涉,尾车空调机组比头车和中间车的负压极值更低,冷凝风流动阻力增大,冷凝风机吸风更加困难。同一车厢的司机室空调机组比客室空调机组更靠近端部,因此冷凝风量下降比更大。

罗茨真空机组系统稳定性的提升

为解决螺杆真空系统运行效率低、真空稳定性差的问题,增强对螺杆真空控制系统的温度、电流、压力的监控,降低了事故处理的滞后性;增加板式换热器及列管冷凝器,冷却了热态气体,降低了真空泵负荷,提升了真空泵运行效率;对三级真空泵进行变频升级,有效调整了产能需求,保证了设备运行的最佳效率。通过以上工艺、设备、电气方面的调整,螺杆真空泵持续、高效的稳定运行得以实现。

某组合式空调机组风管滴水原因及解决方案

以某商场组合式空调机组风管滴水的工程为例,通过勘验其冷水管、冷凝水排水量、冷凝水管坡度、冷凝水管布置以及风管连接情况,确定了该系统冷凝水排水不畅为风管滴水的主要原因,而根本原因在于冷凝水管因施工工期紧、交错施工导致的坡度不达标问题。最终提出了针对本例较为经济的解决方案。施工前期应用BIM技术可有效避免出现管线坡度不达标甚至管线碰撞的问题。

600 MW超临界机组凝结水泵节能改造实践

探讨了凝结水泵变频调速技术的原理,并进行了变频改造试验分析和节能经济性分析。经过凝结水泵变频改造后,机组在低负荷时可节约电率51%,在高负荷时可节约电率13%~35%,节电效果显著,为企业节省了成本。

背压机组与抽凝机组经济性计算方法改进研究

传统的火电厂技术经济指标计算方法着眼于系统用能的数量平衡,反映的只是能量的外部损失,无法揭示系统内部存在的能量质量损失,在计算背压机组的技术经济指标方面存在缺陷,无法真实体现采用背压机组热电联产项目的能量利用水平。对三类计算热电联产机组技术经济指标的分析方法进行简要分析,并基于热力学第二定律,提出兼顾能量的数量特性与质量特性分析热电联产项目能量利用水平的改进方法,结合具体算例,计算并对比背压机组和抽凝机组的技术经济指标。结果表明:随着供热量的增加,热电联产的供热煤耗率将下降;当抽凝机组的热电比高于某个临界值时,抽凝机组的能源转换效率将高于背压机组,证明“背压机组是效率最高的热电联产方式”的观点是值得商榷的。

抽凝改背压机组汽水系统方案设计与对比分析

上海汽轮机厂60 MW等级单缸抽汽凝汽式机组需要改造为30 MW背压式发电机组。抽汽凝汽式机组的汽封系统为供汽和漏汽结合,而背压式机组只有漏汽汽封系统,二者完全不同。介绍了其中汽水系统的设计改造方案。在最大限度保留原有机组设备,包括其辅助系统的原则下,针对汽封和疏水系统进行了改造,尽可能使各接口的压力和管道走向等与原机组匹配。由于取消了机组抽汽,且后半缸在闷板之后光轴运行,因此疏水点和系统配置需要重新设计。提出了2个汽封系统的改造方案,即封堵部分漏汽腔室,保留外部2档漏汽接管的方案,以及利用原有漏汽管道对端部汽封接法进行合理优化,以匹配背压机组需求的方案,并进行了比较。以二者对机组的性能影响和配置便捷性为标准,确定后者为优选方案。研究成果可为类似的改造项目中汽水系统的设计提供参考。

供热机组不同抽汽工况下能耗特性数值研究

供热机组能耗特性的研究对节能减排及实现“碳达峰”和“碳中和”具有重要意义。搭建了350 MW供热机组EBSILON计算模型,主要研究再热压损及凝汽器压力变化时对机组热耗和煤耗的影响。结果表明,当电负荷不变时,煤耗率随着热电比的增大而减小;随着再热蒸汽压损的增大,机组煤耗量和热耗量也增大;随着电负荷越小,再热蒸汽压损对煤耗和热耗的影响越大;机组煤耗量和热耗量随着凝汽器压力的增大而增大,在参数变化范围内,当电负荷为260 MW时,凝汽器压力升到6.0 kPa,发电煤耗变化为1.05 g·(kWh)^(-1)。

吸附法油气回收装置参数优化及改造提升探索

基于油库活性炭吸附法油气回收装置的运行原理和实际运行过程中存在的问题,以油气回收处理能力700 m^(3)/h的油库为例,从优化运行参数和新增装置两方面对回收系统进行优化改造,结果表明:优化炭床吸附设定值、吸收塔高低液位保护设定值、活性炭高温报警值和进油流量可提高油气回收效率;新增的引风系统和冷凝装置,可提高油气回收效率且能达到排放要求。采用以上改造提升方案,油库油气回收效率可提高2‰,按照汽油年出库30×10^(4)t,每吨1万元计,单库回收增量30万人民币/年。