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冷媒除霜系统应用于冻结库时除霜性能研究 总被引:1,自引:0,他引:1
基于优化冷风机结构为目的的冷媒除霜系统应用于冻结库中,通过采用6mm翅片间距的冷风机进行冻结过程中除霜与不除霜的对比实验。并且研究除霜过程对库温波动、冻结物温度波动、冻结时间等参数的影响,以及系统运行的特性。研究表明:应用冷媒除霜系统,每次除霜对库内造成的温度波动都在5℃以内、除霜过程对冻结物温度不产生波动、除霜情况的冻结时间较不除霜缩短了一小时,并且选择除霜对系统更节能。因此,在冷媒除霜系统中采用适时除霜的方式不仅可以避免翅片间隙被冰霜封堵,还可以缩小冷风机翅片间距。在相同换热面积下,缩小冷风机翅片间距还可以达到减小冷风机体积和占地面积的效果。 相似文献
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对采用临界喷嘴式分流器的冷库用翅片蒸发器性能进行实验研究,在0、-4、-8、-12、-16、-18及-20℃七种不同环境工况下进行传热性能测试,并将测试结果与采用气液分离式分流器、CAL分流器和文丘里式分流器进行对比分析。研究结果表明:库温为0℃时,对应的翅片式蒸发器的制冷量和传热系数分别为8.5 kW和37.9 W/(m~2·℃),相比气液分离式分流器、德国CAL分流器、文丘里分流器其对应冷风机的制冷量分别提高了8.1%、17.4%和21.7%,传热系数提高了4.5%、13.9%和18.6%。库温为-18℃时,对应的翅片式蒸发器的制冷量和传热系数分别为5.5 kW和30.9 W/(m~2·℃),其对应的蒸发器的制冷量分别提高了7.2%、14.3%和18.7%。库温为-18℃时,对应的传热系数分别提高了0.9%、10.1%和13.2%。实验结论为有效提高翅片蒸发器性能提供了一种解决方案。 相似文献
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针对直接空冷风机入口流量下降问题,搭建了直接空冷风机阵列1∶10等比例缩小实验系统,进行了风机群分区频率调节实验。使用经验模态分解法对环境风速、风向进行预处理后,计算了用于衡量风机容积损失的风机容积效率,最后采用随机森林回归算法对实验结果进行泛化并估计不同工况下的风机容积效率。结果表明:直接空冷系统中风机容积效率受位置、运行方式、风机频率及环境风速的影响;在环境风影响下,风机群迎风风机的容积效率随环境风速的增大而减小,背风风机的容积效率随环境风速的增大而上升。不同风机频率及环境风速下的风机容积效率曲线为直接空冷系统风机群的节能运行提供参考。 相似文献
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为了解决我国北方地区风电的弃风问题,改进剩余风电供暖系统的直接消纳储能技术,改善电蓄热供暖控制系统中存在换能装置电热转化效率低下的问题,经过方案对比提出采用电热转换效率高、安全可靠性好的电磁感应加热装置作为供暖系统的换能装置。为优化储能水箱加热供暖系统的控制策略,针对系统给定的控制需求,采取前级附加给定温度模糊控制器串联后级感应加热模糊PID控制器的复合控制策略,使闭环加热系统的给定温度随室外温度的变化而调整;同时为了节约不可再生能源,降低损耗,采用与后级模糊PID控制器的输出构成闭环比值随动控制系统的加热循环流量协调控制策略。利用Matlab/Simulink软件进行仿真实验,结果表明:模糊PID控制特性明显优于传统PID控制,系统的超调量显著减少,动态调节速度明显加快;实现模糊控制和模糊PID控制复合与协调智能控制策略的网络化,提高了系统控制的实时性和可靠性,使系统控制性能大为提升。 相似文献
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变频调速技术在涡轮增压器试验台上的应用 总被引:1,自引:0,他引:1
介绍了交流变频技术在涡轮增压器试验台上的应用及原理,采用变频技术后,不但使增压器转速控制更准确、简捷,而且提高了压气机空气流量测试精度。 相似文献
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We present a study of the effects of para–ortho conversion on performance of an adsorption-based hydrogen storage system using finite element methods implemented in COMSOL Multiphysics 4.3a platform. The base model which does not take into account the para–ortho conversion is validated using the experimental data of Maxsorb activated carbon measured with a test bench at room and cryogenic temperatures. The validated model is subsequently applied to simulate the storage system filled with MOF-5 and then extended to investigate the effects of endothermic para–ortho conversion of hydrogen isomers on storage and thermal performances during hydrogen charging/discharging cycle for four inlet temperatures, 35, 50, 77 and 100 K. Our results show that the endothermic conversion reduces the system temperature and increases the net storage capacity. The temperature changes due to the different heat sources are used to investigate the effect of conversion on the temperature reduction. The adsorbed and gas phase masses in the storage system with and without conversion at the end of the charging time are used to determine the effect of conversion on the storage system capacity. Even though the conversion is more significant at low temperature (35 K), the gains are larger at high temperature (100 K). 相似文献
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浅析水泵采用变频调速的必要性 总被引:2,自引:0,他引:2
本文根据江西铜业集团公司贵溪冶炼厂供水车间生产实际和现状,分析比较生活水泵采用变频调速后,生产安全稳定可靠,节能效果显著,并提出生产水泵采用变频调速的必要性。 相似文献
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《Renewable Energy》2000,19(1-2):259-275
This paper briefly reviews the need for renewable power generation and describes a medium-power Autonomous Renewable Energy Conversion System (ARECS), integrating conversion of wind and solar energy sources. The objectives of the paper are to extract maximum power from the proposed wind energy conversion scheme and to transfer this power and the power derived by the photovoltaic system in a high efficiency way to a local isolated load. The wind energy conversion operates at variable shaft speed yielding an improved annual energy production over constant speed systems. An induction generator (IG) has been used because of its reduced cost, robustness, absence of separate DC source for excitation, easier dismounting and maintenance. The maximum energy transfer of the wind energy is assured by a simple and reliable control strategy adjusting the stator frequency of the IG so that the power drawn is equal to the peak power production of the wind turbine at any wind speed. The presented control strategy also provides an optimal efficiency operation of the IG by applying a quadratic dependence between the IG terminal voltage and frequency V∼f2. For improving the total system efficiency, high efficiency converters have been designed and implemented. The modular principle of the proposed DC/DC conversion provides the possibility for modifying the system structure depending on different conditions. The configuration of the presented ARECS and the implementation of the proposed control algorithm for optimal power transfer are fully discussed. The stability and dynamic performance as well as the different operation modes of the proposed control and the operation of the converters are illustrated and verified on an experimental prototype. 相似文献
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王跃 《电网与水力发电进展》2013,29(11):123-125
为解决以偏差为基础的PID控制策略不能满足抽水蓄能机组在不同水头下有较好启动特性的问题,研究了抽水蓄能机组调速器智能启动策略,启动过程的控制目标以机组转速的微分与转速偏差的比值为常数,采用闭环开机控制方式,将机组开机时的转速上升期望特性设置为频率给定,使机组转速变化的动态过程强制转变为按照指数衰减的过程,可实现抽水蓄能机组快速平稳开机并网。 相似文献
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