共查询到20条相似文献，搜索用时 483 毫秒
1.
分别建立了污水源热泵四大部件（蒸发器、压缩机、冷凝器、膨胀阀）模型，并进行耦合。采用MATLAB软件进行编程模拟，分别计算了污垢热阻、污水流量、污水进口温度变化对热泵冬季制热性能的影响。结果显示：当污垢热阻在0~1（m2·K）/kW范围内变化，系统制热量由353 kW降低到301 kW，降低了14.8%；当污水入口温度由8 ℃升高到20 ℃时，系统制热量由320 kW升高到423 kW，升高了32.1%；当污水流量由10 kg/s升到20 kg/s时，系统制热量由339 kW增加到364 kW等。过程中热泵COP在3.6~4.8范围内变化，说明污水源热泵具有较好的热性能。 相似文献
2.
通过夏季工况的地源热泵运行试验,对运行过程中水平埋管的换热性能参数、试验场地周围气象因素和换热过程中土体的温湿度变化等因素进行实时监测,探讨了地源热泵运行过程中水平埋管换热器热交换性能及其周围土壤的温、湿度场变化规律。研究结果表明,地源热泵间隙运行有利于土壤温度场的恢复,随着停机时间的增加,水平埋管与周围土壤的热交换能力明显提高;气候变化对水平埋管周围土壤的温度场分布具有显著影响,随着埋深的递减,土壤温度受气候变化的影响越明显;水平埋管周围土壤温度的变化幅度随着与埋管距离的增加呈递减趋势,其影响半径为1.0m左右;热交换对水平埋管周围土壤湿度场的影响不明显,但大气降雨引起的地表水入渗对土壤湿度场的分布具有显著影响。 相似文献
3.
地源热泵技术在中国温室设施中的应用探讨 总被引：3，自引：2，他引：3
当前在中国温室设施中应用和推广地源热泵技术尚存在诸多不利因素,大大限制了该项技术在设施农业领域中的发展。为探寻合理的解决途径,对地源热泵空调系统的关键技术和其在中国的发展概况进行了相关的阐述和分析,并以中国农业大学上庄实验站已经建成使用的地下水式温室地源热泵空调系统为实例,介绍该系统的组成、工作流程、性能参数和使用情况,探讨温室地源热泵空调系统在推广和使用中可能出现的投资较高,长时间运行性能不稳定等问题,分析其原因并提出相应的对策建议。 相似文献
4.
谷物热泵就仓干燥过程分析与探讨 总被引：6，自引：2，他引：4
利用谷物的传热传质以及干燥速率方程,建立了低温谷物干燥模型,分析了通风量、空气温度以及湿度对谷物干燥过程的影响.模拟了外界空气温度为15℃,湿度为60%RH时,常温通风、加热通风、以及除湿 加热通风三种通风方式对谷物干燥过程影响的情况,并进行了对比.研究表明,10 d稻谷降低2%水分的平均通风量约为30 m3·h-1·t-1,空气含湿量比空气温度对谷物干燥的影响要大,当谷物初始温度和水分含量比较大时,除湿与加热空气结合的效果比单独加热通风的效果要好得多,谷物初始水分含量和温度相对较低时,可以直接通风干燥.建议干燥初期采用除湿与加热相结合或直接加热通风,干燥后期可以直接通风. 相似文献
5.
针对现有辣椒干燥机热风系统温度不稳定及温度控制困难等问题．依据辣椒的干燥特性设计了一种热风控制系统。该系统根据辣椒恒速干燥阶段和降速干燥阶段对热风温度的不同要求．采用在恒速干燥阶段配入冷空气、降速干燥阶段收集恒速干燥阶段尾气并配入新鲜热空气的方法．实现辣椒干燥机中热风温度的准确调控,降低干燥能耗。结果表明：设计的辣椒干燥机热风系统控制的热风温度平均值与预设值的差值仅为±3．5℃,辣椒干燥的平均含水率为13．98％,色泽的α值平均为31.4,热风控制系统工作稳定．其性能可满足实际生产的需求。 相似文献
6.
建立了太阳能喷射-压缩复合制冷系统的实验研究平台,基于EES软件程序进行系统稳态仿真,实验验证了仿真模拟程序的正确性,分析了不同发生温度、中间温度对系统性能的影响。研究表明,在中间温度和冷凝温度不变的情况下,随着发生温度的升高,总功率先降低后升高,系统EER先升高后降低;同时,系统COP呈先逐渐升高而后降低的趋势。在研究范围内,最优发生温度工作区域为78~80℃,此时,系统的总耗功量最小;最优中间温度工作区域为7~10℃,此时,系统制冷量达2 245 W,EER最高为3.39。 相似文献
7.
《分子植物育种》2016,(12)
以珍稀濒危植物秦岭岩白菜种子为材料,研究了温度、光照对种子萌发的影响,旨在揭示秦岭岩白菜种子的萌发特性,为人工扩繁体系的构建及野生种群的回归复壮提供依据。结果表明,温度和光照对秦岭岩白菜种子萌发有显著影响,两者互作对种子萌发无显著影响。在适宜的温度下(20℃~25℃),秦岭岩白菜种子萌发启动快,发芽势、发芽指数和发芽率高;温度过低(10℃)或过高(30℃)种子萌发延迟,发芽势、发芽指数和发芽率明显降低。光照对种子萌发的起始时间无明显影响;但全光照或半光/半暗条件下,种子的发芽势、发芽指数和发芽率明显比黑暗条件下高。温度是影响秦岭岩白菜种子萌发的重要因素,在20℃~25℃下采取全光照或半光/半暗环境有利于种子萌发和幼苗建成。 相似文献
8.
简单屋顶绿化的滞蓄特性 总被引：2，自引：0，他引：2
设计了模拟降雨与数据采集系统,研究了短时强降雨下简单屋顶绿化基质(配比：陶粒57.0%、草炭41.5%、保水剂1.5%)的降雨产流过程,基于37次模拟降雨实验,归纳了降雨产流的一般过程、规律和特性,分析了降雨强度、基质厚度和基质初始含水率对简单屋顶绿化滞流蓄水特性的影响。结果表明：基质厚度和基质初始含水率对简单屋顶绿化的蓄水特性有显著影响,基质初始含水率越低、基质厚度越厚时蓄水特性越佳。建立了产流时间数学模型,简单屋顶绿化降雨产流时间与降雨强度呈负相关,同时也受初始含水量和基质厚度影响。随着干湿循环次数增加,基质的厚度总体呈现下降趋势,储水性能逐渐下降,延迟产流时间逐渐缩短。 相似文献
9.
播种期温度变化对玉米出苗速率的影响 总被引：5，自引：3，他引：2
为了应对气候变化,掌握玉米播种出苗期的温度特性,科学调整玉米播种期提供依据,采用分期播种方法,研究温度变化对玉米出苗速率的影响。结果表明,随着春季气温的升高,玉米出苗速率加快。玉米出苗速率与4月中旬—6月上旬平均气温存在对数函数关系,与≥12.0℃有效积温存在线性函数关系,出苗天数与活动积温存在指数函数关系。稳定通过12.0℃为玉米播种初始温度,14.0~18.0℃为较适宜温度,18.0℃以上为播种适宜温度。耕层温度与气温对出苗速率的影响相同。播种期初始温度应从稳定10.0℃调整至稳定12.0℃为宜。 相似文献
10.
在制冷系统的运行中,通过自动控制可以使系统安全稳定的工作,保证储藏食品的质量,提高系统的运行性能,节约能源消耗及降低运行成本等.制冷装置的自动控制系统,可以对制冷系统参数如压力、温度、湿度、流量、液位、空气成分等自动检测和调节,还可以对制冷机器和设备进行保护,以避免发生事故.系统中的控制器可采用双位、比例(P)、比例积分(PI)或比例积分微分(PID)控制器等.制冷装置的自动控制系统一般采用负反馈调节系统,为了提高控制精度,还可以采用串级、前馈等调节系统. 相似文献
11.
For the capillary mats using wet construction, a winter experiment designed to investigate the heat transfer performance was described, and the heat transfer performance analysis which contains the comparisons between different pipe space and different thickness of cement mortar surface was carried out. As a result, compared with that of the traditional radiant heating pipes, the capillary mats of wet construction require supply water with lower temperature, and it shows good heat transfer performance and system energy efficiency as well. According to the demand of indoor heat dissipation and human comfort as well as the coupling relationship between the temperature of supply water and surface construction thickness, it is suggested that the proper construction method should be comprehensively considered in practical applications. 相似文献
12.
This paper describes the double layer horizontal ground source heat pump systems constructed in 1998 with the buried depth of 0.9 m and 1.8 m. The program of study includes experimental equipments, heat exchanger size, testing meter and methods for data analysis. In addition, the heating and cooling performance at typical days are also illustrated. Among the influencing factors on the performance of the ground source heat pump systems, the parameter of heat exchanger and operation patterns of heat pump systems are analyzed.A heat transfer model has been set up for horizontal heat exchanger. 相似文献
13.
Load dynamic matching of supply and demand side based on the utilization of urban sewage heat energy
Flowing dynamic characteristics and its temperature dynamic characteristics of a three-level sewage pipe network in Chongqing were analyzed. A mall's building whole year load was simulated. In the adverse condition of wastewater flow, the market construction peak discharge heat was compared with the sewage heat load, the balance between the most adverse flow and the building demand was found. Explored supply and demand matching method between urban sewage and city building load in flow adverse condition to take full advantage of the urban sewage cold and hot resources. the composite system was adeptcd to make up the most unfavorable flow time of sewage average heat load and the construction load difference; it also puts forward principle of load sharing and control strategy aimed at compound system. 相似文献
14.
15.
It is helpful for energy efftciency to use distributed pumps instead of valves to regulate hydraulic balance in a district heating system (DHS). A new scheme of distributed pump-system is presented based on performance comparison of hydraulic regime and power saving of single-heat-source dendritic pipeline networks with regulating valves and/or distributed pumps. Supposing that the new scheme was employed in multi-sources looped-pipe network, theoretical analysis and case study were carried out to evaluate off-design performances including hydraulic self-regulation, supply water temperature stability and power-saving potential. The results indicated that the proposed scheme would contribute to minimizing power consumption, retarding water temperature change, and would be convenient to adjust the quality and quantity independently in the looped-pipe heat supply networks. 相似文献
16.
为解决冬春季温室育苗环境温度低的问题,设计基于碳晶电热膜的温室育苗保温加温系统,并于冬季最冷时段在河北省永清县的连栋玻璃温室内对系统的保温加温性能进行实际测试。以无加温育苗试验区作为对照,研究分析碳晶电热膜根区加温对基质温度和空气温度的影响,探讨苗床上保温覆盖的保温作用和加温的均匀性。结果表明,单层膜保温覆盖可使加温育苗区内空气平均温度值较温室内高1℃;碳晶电热膜加温可使基质温度平均值及最低值提高7.3℃和10.7℃;基质温度最低值偏离度为2.9%,平均值为6.1%。基于碳晶电热膜的温室育苗保温加温系统可有效提高育苗环境温度且加温均匀性高,为培育高质量种苗提供有力保障。 相似文献
17.
锅炉设备在食品工业中的应用范围很广,很多的食品企业都应用锅炉的蒸汽进行加热操作。介绍了中小型食品生产线对锅炉设备的选型标准及安装形式,以及锅炉蒸汽管路与食品生产线成套设备安装的工程监理,以期为在实际生产操作中选择合适的锅炉设备和降低安装成本提供参考。 相似文献
18.
The homogeneous charge compression ignition (HCCI) characteristics of diisobutylene are studied numerically. Numerical results are in accord with the corresponding experimental data. The influence of some key parameters such as initial pressure, equivalence ratio and constituent on autoignition characteristics is discussed and combustion characteristics of diisobutylene in HCCI engine are analyzed. The results indicate that the ignition delay decreases with the increase of pressure and equivalence ratio. The maximum temperature increases with the rise of equivalence ratio, but it does not change with the variation of initial pressure. The 1 pentene isomer ignites significantly faster than the 2 pentene isomer and the ignition delay for the blend directly depends on the proportions of each isomer. It can be found that diisobutylene shows the single stage autoignition. The maximum heat production rate of the 2 pentene is lower than that of 1 pentene, but the 2 pentene still provides good power performance. 相似文献
19.
To be effectively heated in incinerator for MSW is very important for stabilization and completeness combustion, the smaller produce of the PCDD/Fs. At the same time, the transient heat transfer characteristics of the MSW lump decides the stay time of the MSW in incinerator and effects on the operation feature of the combustion equipments. All of these would lead to design the reasonable and clean combustion project, the optimum incinerator and recover energy system. The component, shape, dimension, property, the hardly and inner structure feature of the MSW lump are taken in account, and the effective conduct heat coefficient has been adopted. And then, the physical model is setup with different shape(ball, cylinder, squareness), and the 3-D mathematical model and conduct heat efficient with porous feature for transient heat transfer of MSW lump are presented, at the same time, the simulation tests are gotten in various boundary and the interesting conclusions are gotten: The center stable temperature of the MSW lump is mostly decided by the inner gas temperature of the incinerator and the heated area of the lump. The transient heat transfer characteristics is variously effected by the shape of the MSW lump in incinerator. The transient process becomes longer and the center stable temperature decreases, the volatile can't be easily separated out and the combustion efficiency decreases because of the increasing of the lump feature dimension. 相似文献
20.
变流量冷冻水系统温差控制法的适用性 总被引：1，自引：0，他引：1
研究了末端设置通断控制阀的一次泵变流量系统在温差控制下的水力特性,并结合风机盘管与房间的非线性换热耦合特性,进一步探讨了温差控制的适用条件以及变温差控制温差值的设定方法。结果表明：末端设置通断控制阀的系统,当管网整体负荷分布均匀且各开启用户的负荷变化规律相近时,温差控制同样是较为适用的,此时系统的水力失调对室内温湿度的影响较小;采用变温差控制时,仅以不同的总负荷率分段设置温差值,并不能获得良好的室内温湿度控制效果,建议以优先保证风盘除湿能力和室内干球温度为原则设定温差值,相比于目前的方法,在同等的室内相对湿度波动下,室内温度的稳定性可以得到保证。 相似文献