1000MW直接空冷机组汽泵冷凝采用蒸发式冷凝器的探讨

在分析蒸发式冷凝器工作原理的基础上,对1 000MW超超临界直接空冷机组汽动给水泵小汽轮机冷凝采用蒸发式冷凝器的可行性进行了系统分析,对分别采用蒸发式冷凝器和带湿冷塔的湿式循环冷却系统的用水特性及经济性进行了对比,并介绍了蒸发式冷凝器在国外火电厂的应用情况.研究表明,蒸发式冷凝器与带湿冷塔的湿式循环冷却系统相比,具有节能、节水、运行费用低和投资少等诸多优点,特别适合于强调节能和节水的空冷式发电机组汽泵的冷凝,在我国推广这项技术十分必要.该文为蒸发式冷凝器在国内火电厂中的应用推广提供参考.     

用于汽轮机排汽冷却的蒸发式冷凝器模型及性能分析

蒸发式冷凝器兼具传热性能好和节水的优势,在大型动力系统冷却中具有广阔的应用前景。建立了蒸发冷凝器的理论分析模型,提出了蒸发式冷凝器用于冷却小型汽轮机排汽的设计方案;获得了喷淋水温度、空气和蒸汽的焓值在冷凝器内沿程的变化规律,并对喷淋水量、配风量和空气温度等影响冷凝器性能的影响因素进行了分析。研究结果对蒸发式冷凝器在火力发电行业的应用具有参考意义。     

蒸发式冷凝器在啤酒生产中的应用效果

为了降低电耗和水耗、减少环境污染和保障运行安全,对啤酒生产冷冻站设备进行了技术改造,用蒸发式冷凝器代替立式冷凝器.通过对蒸发式冷凝器与原立式冷凝器的运行情况对比,系统地分析了技术改造带来的节能减排效果和经济效益.     

蒸发式冷凝器在制冷系统中的应用

蒸发式冷凝器是制冷系统主要的热交换设备之一,较之于水冷式冷凝器具有电耗省、水耗低、材耗少、占地面积小等优点。因此,国际上发达国家诸如美国、加拿大等国,从上世纪七十年代起,在冷库中已普遍采用蒸发式冷凝器,我国从上世纪八十年代起,在化工行业和食品冷库工程中也开始采用蒸发式冷凝器,逐步替代水冷式冷凝器。近二十几年来应用实践证明,蒸发式冷凝器具有明显的节能效果,是一种能源节约型产品,具有良好的发展前景。     

蒸发式冷凝器的盘管截面形状对传热影响的数值模拟

随着蒸发式冷凝器在各行业的应用越来越广泛,对其换热能力的研究也在不断地深入。针对蒸发式冷凝器盘管截面形状对强化换热的影响。应用计算流体力学的知识,对蒸发式冷凝器不同的截面形状对换热影响进行了研究分析。通过使用Fluent模拟得到盘管截面的云图结果得出如下结论:在材料相同的情况下,椭圆管截面相比于圆形截面,周围的压强要低,流速更快,同时换热系数要提高2%左右,更有利于换热,因而使用椭圆截面替代圆形截面可以实现强化换热的目的。     

制冷系统采用蒸发式冷凝器的节能效果

1 3种冷凝器的比较 冷凝器是制冷系统主要的热交换设备之一，其作用是将压缩机排出的高温的过热制冷介质蒸汽冷却成为液态。常用的冷凝器按其冷却介质和冷却方式一般可分为三种类型：水冷式（又分为壳管式、套管式、沉浸式等）、空气冷却式（或称风冷式）及蒸发式（制冷剂在管内冷凝，管外同时受到水及空气的冷却）。不同形式的冷凝器，水泵和风机的能耗也不同，不合适的选型和配置会造成的冷凝压力过高过低，影响压缩机压缩过程的耗功和制冷效果，因此，正确的选型与配置冷凝器，应该引起重视。     

益美高ATC型蒸发式冷凝器的节能应用

正1企业简介益美高公司(Evapco Inc.)成立于1976年,总部位于美国马里兰州,是世界知名的换热设备制造商,产品包括蒸发式冷凝器、冷却塔、工业冷风机、循环泵组、制冷剂输送系统、热交换器、压力容器等,广泛应用于商用空调、工业制冷、工艺加工、区域供冷及电力行业的冷却与制冷系统中。益美高于1995年来到中国,是第一家进驻中国的外资冷凝器生产厂家。益美高生产的蒸发式冷凝器产品在国内的啤酒、饮料、制药、石油、化工、冷库等行业     

专利信息

专利信息新型热管式平板集热器本实用新型为一种新型热管式平板集热器。它由若干单元热管系统组成。每一热管系统包括有平板式吸热板、喉管、冷凝器和通水管。平板式吸热板上滑板垂直向下布设工质蒸发回路；在平板式吸热板的顶端有工质蒸发回路的进出口，该进出口向下通过...     

蒸发冷却式冷水机组能耗模型实验研究

针对蒸发冷却式冷水机组能耗模型进行实验研究。比较蒸发冷却式冷水机组与普通冷水机组在工作原理存在的异同并分析室外气象参数对系统能耗影响的基础上,用冷凝器侧进口空气的焓值影响替代普通冷水机组能耗模型中的冷却水进口温度影响,建立了蒸发冷却式冷水机组的能耗模型,并利用实测数据进行了参数估计与误差检验,结果显示改进模型的验证误差在8%以内,在精度上比现有模型有了较大的提升。     

大功率晶闸管的冷却技术

简要介绍了晶闸管各种冷却方式的特点、原理及其发展现状。认为浸泡式蒸发冷却具有不可比拟的优越性和很好的发展前途。由于浸泡式蒸发冷却要用完全密闭形式,导致系统内部压力在真空到0.3MPa之间波动。而大型冷却容器作为压力容器受到法律限制,因此严重影响了它的发展。鉴于此,提出了恒压浸泡式蒸发冷却系统,并对其特点及原理做了简单分析。     

A new approach to analysis and optimization of evaporative cooling system II: Applications

After introducing the concepts of moisture entransy, moisture entransy dissipation and thermal resistance based on moisture entransy dissipation (TRMED) in part I of this study, we further analyze several direct/indirect evaporative cooling processes based on the above concepts in this part. The nature of moisture entransy, moisture entransy dissipation and TRMED during evaporative cooling processes was reexamined. The results demonstrate that it is the moisture entransy, not the enthalpy, that represents the endothermic ability of a moist air, and reducing the entransy dissipation by both enlarging the thermal conductance of heat and mass transfer, and decreasing the temperature potential of the moist air, i.e. the difference between the dry-bulb temperature of moist air over its dew-point temperature, will result in a smaller system TRMED, and consequently a better evaporative cooling performance. Then, a minimum thermal resistance law for optimizing evaporative cooling systems is developed. For given mass flow rates of both moist air and water, with prescribed moist air and water conditions, minimizing the TRMED will actually lead to the most efficient evaporative cooling performance. Finally, the thermal conductance allocation for an indirect evaporative cooling system is optimized to illustrate the application of the proposed minimum thermal resistance law.     

Evaluation of cooling technologies of concentrated solar power plants and their combination with desalination in the mediterranean area

Different alternatives for the effective integration of desalination technologies in the cooling of concentrating solar power (CSP) plants in the Mediterranean area are discussed and evaluated. Two cases are considered where a low temperature multi-effect distillation (LT-MED) plant is integrated into a CSP plant replacing the condenser of the power cycle. In one case, a LT-MED plant is fed by steam at the outlet of the turbine expanded to 70 °C. In the other case a LT-MED is fed by the steam obtained from a thermal vapour compressor (TVC) which uses the exhaust steam of the CSP plant (at 37 °C, 0.063 bar) together with some from the high pressure turbine extraction (17 bar). The two cases are compared with that of a reverse osmosis (RO) unit powered by the electricity produced by the CSP plant. In this case, two different wet cooling technologies, once-through and evaporative water cooling, and a dry air cooling are considered for the CSP plant. Thermodynamic simulations are presented for all cases, together with an economic analysis.     

Thermal performance of roof evaporative cooling and floor coupled evaporatively cooled underground water storage tank systems

The thermal performance of a room with two indirect evaporative cooling systems (operating independently and jointly) is analysed. The two evaporative systems considered are a water-film roof evaporative cooling system, and an underground water storage tank beneath the floor of the room. The water in the tank is evaporatively cooled through a suitable aeration system. The performance of the room is analysed in the hot-dry climate of Jodhpur and the composite climate of Delhi. It is found that the underground water storage system is marginally better than the roof evaporative cooling system for the Jodhpur and Delhi climates. A detailed parametric performance analysis of the room has also been carried out.     

Experimental Evaluation of One,Two, and Three Stage Evaporative Cooling Systems

The thermal performance of four different arrangements of evaporative air coolers have been evaluated experimentally during the hot summer of Kuwait. The systems include one-stage direct evaporative cooling (DEC), one-stage indirect evaporative cooler (IEC) linked to an external cooling tower, two-stage indirect/direct evaporative coolers (IEC/DEC), and three-stage system of evaporative cooling and mechanical vapor compression (IEC/DEC-MVC). Two variables are used to evaluate the system thermal performance, the thermal effectiveness and the energy efficiency ratio (EER). The data show that the IEC/DEC has the highest EER, followed by the DEC, IEC/DEC-MVC, and IEC. The DEC has the lowest effectiveness, succeeded by the DEC/IEC, IEC, and IEC/DEC-MVC. Coupling MVC with IEC/DEC extends the cooling range and can cool the ambient air dry bulb temperature over a range of 40°C to 15°C at any value of ambient air wet bulb temperature. Two experimental correlations have been developed for each one of the tested systems. The first one relates the effectiveness to water to air mass flow ratio (L/G) or Reynolds number (Re), while the second correlation relates the EER with effectiveness and L/G and/or Re. These relationships are very important in designing and optimizing the studied evaporative cooling units.     

Thermoeconomic optimization of an ice thermal storage system for gas turbine inlet cooling

The gas turbine power output and efficiency decrease with increasing ambient temperature. With compressor inlet air cooling, the air density and mass flow rate as well as the gas turbine net power output increase. The inlet cooling techniques include vapor or absorption refrigeration systems, evaporative cooling systems and thermal energy storage (TES) systems. In this paper the thermoeconomic analysis of ice (latent) thermal energy storage system for gas turbine inlet cooling application was performed. The optimum values of system design parameters were obtained using genetic algorithm optimization technique. The objective function included the capital and operational costs of the gas turbine, vapor compression refrigeration system, without (objective function I) and with (objective function II) corresponding cost due to the system exergy destruction. For gas turbines with net power output in the range of 25-100 MW, the inlet air cooling using a TES system increased the power output in the range of 3.9-25.7%, increased the efficiency in the range 2.1-5.2%, while increased the payback period from about 4 to 7.7 years.     

Thermal performance of an evaporatively cooled building: Parametric studies

A single-storey office building in a hot and dry climate is modelled for evaporative cooling. The counterflow cooling tower is modified to precool the tower inlet air by the tower exit air in a heat exchanger. Centralized evaporative air cooling, using the modified cooling tower, and roof evaporative cooling are considered to provide comfortable living conditions in the space. The thermal performance of such a building is analysed for various operating parameters. The study indicates that centralized evaporative air cooling is feasible, to maintain near-perfect comfort conditions in hot and dry climates. Modified cooling tower and roof evaporative cooling further enhance the scope of evaporative cooling for comfort applications.     

直接蒸发冷却技术在火力发电厂的应用

叙述了直接蒸发冷却技术的原理及应用于火力发电厂汽轮机房通风的方案,指出,直接蒸发冷却方式与传统的机械制冷方式比较,既加强了通风与换气作用,改善了新风运行环境,还能减少运行费用,实现节能减排,具有较大的经济效益。     

Performance enhancement of gas turbines by inlet air‐cooling in hot and humid climates

In this paper, a model to study the effect of inlet air‐cooling on gas turbines power and efficiency is developed for two different cooling techniques, direct mechanical refrigeration and an evaporative water spray cooler. Energy analysis is used to present the performance improvement in terms of power gain ratio and thermal efficiency change factors. Relationships are derived for an open gas turbine cycle with irreversible compression and expansion processes coupled to air‐cooling systems. The obtained results show that the power and efficiency improvements are functions of the ambient conditions and the gas turbine pressure ratio. The performance improvement is calculated for, ambient temperatures from 30 to 50°C, the whole range of humidity ratio (10–100%) and pressure ratio from 8 to 12. For direct mechanical refrigeration air‐cooling, the power improvement is associated with appreciable drop in the thermal efficiency. The maximum power gain can be obtained if the air temperature is reduced to its lowest limit that is the refrigerant evaporation temperature plus the evaporator design temperature difference. Water spray cooling process is sensitive to the ambient relative humidity and is suitable for dry air conditions. The power gain and efficiency enhancement are limited by the wet bulb temperature. The performance of spray evaporative cooler is presented in a dimensionless working graph. The daily performance of the cooling methods is examined for an ABB‐11D5 gas turbine operating under the hot humid conditions of Jeddah, Saudi Arabia. The results indicate that the direct mechanical refrigeration increased the daily power output by 6.77% versus 2.57% for the spray air‐cooling. Copyright © 2005 John Wiley & Sons, Ltd.     

高湿度地区某整理车间蒸发冷却空调系统设计分析

江阴市某纺织品整理车间设计空调系统,对车间进行降温,改善工人工作环境。针对达到规范所要求的室内温湿度和适当放宽室内温湿度(在人体舒适区域内)时,提出蒸发冷却与机械制冷相结合的空调方案及蒸发冷却空调方案,并根据各自方案的特点、风量及制冷量等情况,得出应用蒸发冷却空调的可行性,最后根据此车间的特点,对方案进行优化,使得蒸发冷却与工位送风相结合,初投资和运行费用更低、节能效果更加显著。