Numerical Simulation of Linear Electromagnetic Stirring in Secondary Cooling Region of Slab Caster

According to the theory of alternating magnetohydrodynamics and magnetic boundary renewal method,mathematical models were proposed for electromagnetic stirring in secondary cooling region( SEMS) of slab caster. The magnetic fields and flow fields of melt were simulated with SEMS. It's shown that the electromagnetic forces with inward and sidelong components produced by travel magnetic field at the wide faces of slab make the melt whirling in horizontal section,and the convection of the melt is strengthened obviously there. In addition,magnetic flux density attenuates from the edge to the center of slab,and the profile of the melt velocity along slab thickness in the center of the horizontal section takes a two-opposite-peak configuration. Ultimately,the stirring intensity and features are determined by the electromagnetic parameters,coil arrangement and stirring types.

Possibilities of Using Solar Energy in District Cooling Systems in the Mediterranean Region

Use of district heating and cooling systems has many environmental advantages compared to individual heating and cooling. Recent advances in solar energy technologies for heat and power generation have reduced their cost and promoted their use instead of fossil fuels. Solar-PV energy for electricity generation and solar thermal energy for hot water production are broadly used today. Solar energy resources in the Mediterranean region are abundant while space cooling in buildings is required when solar irradiance is high. The possibility of using solar energy for fuelling water chillers providing cold water in district cooling systems in the Mediterranean basin has been investigated. Existing literature and studies concerning the use of district cooling systems globally as well as the energy sources used in them have been examined. Solar-PV energy combined with compression chillers and solar thermal energy combined with thermally driven chillers can be used for cold water production. Their overall efficiencies, converting solar energy to cold water, vary between 22% and 56% compared with 45% for compression chillers using grid electricity. It is concluded that various solar energy technologies could be used with different types of water chillers for fuelling district cooling networks in the future in the Mediterranean region.

Surface Regional Heat(Cool) Island Effect and Its Diurnal Differences in Arid and Semiarid Resource-based Urban Agglomerations

With the rapid development of urban agglomerations in northwest arid and semiarid regions of China, the scope of the urban heat island(UHI) effect has gradually expanded and gradually connected, and has formed a regional heat island(RHI) with a larger range of impact to the regional environment. However, there are few studies on the heat island effect of urban agglomerations in arid and semiarid regions, so this paper selects the urban agglomeration of Hohhot, Baotou and Ordos(HBO) of Inner Mongolia, China as the study area. Based on the 8-day composite Moderate-resolution Imaging Spectroradiometer(MODIS) surface temperature data(156scenes in all) and land use maps for 2005, 2010, and 2015, we analyze the spatiotemporal distributions of regional heat(cool) islands(RH(C)I) and the responses of surface temperatures to land-use changes in the diurnal and interannual surface cities. The results showed that: 1) from 2005 to 2015, urban areas showed the cold island effect during the day, with the area of the cold island showing a shrinking feature;at night, they showed the heat island effect, with the area of the heat island showing a first decrease and then an increase.2) From 2005 to 2015, the land development(unutilized land to building land) brings the greatest temperature increase(ΔT = 1.36°C)during the day, while the greatest temperature change at night corresponds to the conversion of cultivated land to building land(ΔT =0.78°C) exhibited the largest changes at night. From 2010 to 2015, the land development(grassland to building land) bring the greatest temperature increase(ΔT = 0.85°C) during the day, while the great temperature change at night corresponds to the conversion of water areas to building land(ΔT = 1.38°C) exhibited the largest changes at night. Exploring the spatial and temporal evolution of surface urban heat(cool) islands in urban agglomerations in arid and semiarid regions will help to understand the urbanization characteristics of urban agglomerations and provide a reference for the formulation of policies for the coordinated and healthy development of the region and co-governance of regional environmental problems.

Evaluation of the Preventive Effect of Regional Cooling Nursing on Hand Foot Syndrome Caused by Doxorubicin Hydrochloride Liposome

Purpose: To explore the preventive effect of Regional cooling comprehensive nursing on hand foot syndrome caused by pegylated liposomal doxorubicin (PLD). Method: Adopt overall sampling method. Patients who used the same adjuvant drugs from January to December 2020 were randomly divided into an intervention group and a control group. The patients in the two groups received routine nursing guidance and drug prevention for the use of amygdalin. The patients in the intervention group were required to take protective measures of Regional cooling during chemotherapy. The occurrence of hand foot syndrome during adriamycin liposome administration was compared between the two groups. Results: By comparing the adverse reactions of cases during Adriamycin Administration, the incidence rates of grade I, II and III hand foot syndrome in the control group were 28.8%, 7.6% and 27.5% respectively, and the incidence rates of grade I, II and III hand foot syndrome in the intervention group were 42.1%, 12.3% and 7.0% respectively, with statistical significance (P Conclusion: Regional cooling nursing and preventive behavior guidance can effectively reduce the severity of hand foot syndrome caused by adriamycin.

Analysis of the Cooling Mechanism of a Crushed Rock Embankment in Warm and Lower Temperature Permafrost Regions along the Qinghai-Tibet Railway

Based on data monitored in situ and theoretical analysis,the characteristics of the temperature field and mechanism of thermal conduction of a crushed rock embankment were studied along the Qinghai-Tibet Railway.The results of experi-ments in the field revealed that the cooling effect of a crushed rock embankment is influenced mainly by the natural con-vection in winter and shield effect in summer,the ventilation of crushed rocks,and the ground temperature regime be-neath the embankment.Consequently,these three factors should be taken into account in numerical simulations,but it is as a result of natural convection only.

In-situ testing study on convection and temperature characteristics of a new crushed-rock slope embankment design in a permafrost region

For the purpose of enhancing air convection and controlling solar radiation, a new crushed-rock slope embankment design combined with a sun-shade measure is proposed. A newly designed embankment was constructed in the Tuotuohe section of the Qinghai-Tibet Railway and a field-testing experiment was carried out to determine its convection and temperature characteristics. The results show that distinct air convection occurred in the crushed-rock layer of the new embankment, especially in cold seasons, which was enhanced when it flowed upwards along the slope. This preliminarily indicated that the new design of the embankment slope was good for reinforcing air convection in the crushed-rock layer. The frequent fluctuations of the convection speed and the environmental wind speed were in good agreement, suggesting that the convection in the crushed rock primarily came from the ambient wind. It was also preliminarily determined that the new embankment had a better cooling effect and sun-shade effect for decreasing the temperature of the embankment slope compared with a traditional crushed-rock slope embankment, and the mean temperature difference between them was up to 1.7 °C. The mean annual temperature at the bottom boundary of the crushed-rock layer was obviously lower than that at the top boundary, and heat flux calculation showed that the shallow soil beneath the embankment slope was weakly releasing heat, all of which indicated that the new embankment slope design was beneficial to the thermal stability of the embankment. This study is helpful in providing some references for improved engineering design and maintenance of roadbeds in permafrost regions.

旋流冲击下不同孔型发散冷却壁面耦合传热特性对比

采用红外热成像技术考察了不同冷气压降下圆孔、扇形孔和扩张孔的发散冷却特性。结果表明:由于旋流冲击效应,壁面出现局部低冷效区域,且与孔型无关;孔型变化仅影响壁面的冷却效果,增大冷却空气压降可改善冷效效果,低冷效区域的面积也随之减小;冷却孔型和冷却空气压降的差异会导致最低冷效点位置发生迁移;随着冷气速度的增大,该点位置向上游方向迁移;就均匀性而言,冲击点圆孔的最低效率比面积平均值降低14.3~27.5百分点,扇形孔和扩张孔的最低冷效与平均水平差别更大,冷效均匀性更差;扩张孔的综合冷却效率最高,但均匀性最差。

北疆冷凉区玉米品种筛选试验

为了提高玉米产量,促进农业增产、农民增收,开展了品种筛选试验,以筛选出适宜北疆冷凉区种植的优良玉米品种。结果表明,参试的13个玉米品种熟期相对适中,各品种生育期均早于对照丰垦139,早熟2~7 d,说明各品种在此种植区域皆能安全成熟。KWS9384、兆合402、新玉76、KWS7461这4个品种综合性状表现优良,产量超过对照丰垦139,增产幅度6.24%~11.76%,其中以KWS9384增产较明显,增产幅度达11.76%;KWS7461虽然较丰垦139增产,但其株高、穗位高较高,生产上易发生倒伏;吉单494产量略低于对照丰垦139,但熟期适中,抗倒伏能力强,收获时籽粒含水率较低。综合分析各玉米品种的生育期、产量等因素,适宜北疆冷凉区种植的优良玉米品种有KWS9384、兆合402、新玉76和吉单494。

喷雾降温系统中纯水液滴群蒸发域的模拟研究

为了避免喷雾降温系统中液滴沉降到设备及人体表面对工艺及人体热舒适造成影响,需要针对纯水液滴群蒸发域问题进行研究。本文采用计算流体动力学(CFD)方法,研究了喷雾降温系统作用下,不同热源温度、液滴初始粒径对液滴群蒸发域的影响,分析了室内温度分布及液滴粒径分布,探讨了室内热源温度及液滴初始粒径对蒸发域高度的影响规律。结果表明:随着热源温度的增加,热羽流对喷雾射流的抑制作用增强,液滴群的蒸发域随之增大;当液滴初始粒径增大时,液滴群的蒸发域随之减小,喷雾射流范围内的温度随之增加;液滴群蒸发域高度随着热源温度的增加而呈线性增大,随液滴初始粒径的增加而呈线性减小,当热源温度大于400℃,液滴初始粒径大于60μm时,其对液滴群蒸发域高度的影响较小。

不同空调冷热源对建筑碳排放量的影响分析

随着我国各项建筑节能标准的更新,对于建筑碳排放量控制的要求越来越高,而空调冷热源系统是影响建筑碳排放的重要因素,且随着能源结构优化,区域电网的碳排放因子明显降低,冷热源系统电气化将是碳约束下主要的发展方向。运用eQuest软件对不同类型空调冷热源系统的运行能耗和碳排放强度进行了动态模拟和定量分析,发现冷热源系统的能源利用形式和区域电网的碳排放因子与供暖空调系统的碳排放量密切相关,对冷热源系统选择起决定作用。

围岩变温过程中隧道衬砌结构温度演化特征

铺设隔热层是高地温隧道热害防治的有效方式,探究隧道围岩温度变化过程中衬砌结构温度演化规律可加强对高地温隧道热害防治机理方面的认识。通过数值模拟和模型试验分别研究了围岩升温与降温过程中围岩与隧道结构不同位置温度演化特征,验证了变温过程围岩与隧道结构温度演化特征数值分析模型的准确性,揭示了变温过程隔热层降温性能演化特征。结果表明:围岩升温过程中,围岩与衬砌结构温度随时间延长呈现混合增加、缓慢增加与稳定三阶段演化特征;围岩降温过程中,围岩与衬砌结构温度随时间延长呈现缓慢降低、非线性降低与稳定三阶段演化特征;围岩变温过程不会对隔热层降温幅度产生影响,仅改变围岩结构温度变化形式。本研究可为高聚物隔热材料在高地温隧道中的应用提供理论依据。

辐射致冷对建筑长期能效的影响——七种涂层的实验比较

辐射致冷涂层因其优异的致冷能力和能源效率而被广泛应用。然而,对辐射致冷涂层的耐候性、长期性能和对建筑负荷的影响尚缺乏全面的研究。为了弥补之前研究的不足,对七种涂层的耐温度循环、耐紫外老化、耐自然老化和长期致冷能力进行测试。此外,通过WUFI-Plus软件模拟了使用不同涂层时办公建筑的冷负荷和热负荷。结果显示,不同涂层的抗老化、长期降温和降低建筑负荷能力存在明显差异。实验室测试结果表明,一些涂层在耐候性测试后出现变黄、开裂和剥落的现象,同时辐射性能降低。户外测试结果表明,随着自然老化时间的延长,所有涂层的致冷能力均逐渐下降,且下降速度与涂层的老化速度成正比。建筑负荷模拟结果表明,不同涂层对建筑冷热负荷的影响不同,因此需根据不同气候区的实际使用情况选择适宜的涂层。

京津冀地区采暖与降温度日时空变化特征研究

利用京津冀地区1961年-2015年逐日平均气温数据,分析了采暖度日(HDD)与降温度日(CDD)的时空分布与变化特征,探讨了城市化和地形对HDD与CDD的影响。结果表明:京津冀地区HDD与CDD分布具有明显的纬度特征,同时又受到地形影响。年均HDD总体表现为下降趋势,西北山地和一些城区站的下降趋势较大;CDD总体表现为增加趋势,城区上升趋势最大且年际波动较大。北京地区代表台站分析表明,不论是HDD还是CDD,均表现为城市化对近郊和城区的站点影响明显,对远郊站点影响较小。度日与海拔之间具有较好的相关性。

热带太平洋海洋叶绿素对SST的影响及其机理分析——基于ROMS的海洋物理-生态模式模拟

关于热带太平洋海洋叶绿素对海表面温度(sea surface temperature, SST)年平均场和年际变率的影响,学术界存在着广泛的争议,模拟结果表现出明显的模式依赖性;且对于季节变化上叶绿素如何影响SST的关注较少。为深入研究热带太平洋叶绿素的气候效应,本文基于区域海洋模式系统(Regional Ocean Modeling System, ROMS)构建了海洋物理-生态耦合模式;通过在敏感性试验中设置不同的叶绿素浓度分布,分析了叶绿素对热带太平洋SST的年平均和季节变化的影响。结果表明,叶绿素会导致热带太平洋大部分区域SST升高,但赤道东太平洋区域SST降低。其中,前者由叶绿素的直接加热效应所引起:叶绿素的存在使得海洋表层吸收的短波辐射明显增多,更多的热量被保留在了混合层中,引起SST的升高;后者由动力冷却效应占主导:叶绿素使得混合层中吸收更多的短波辐射,导致穿透到混合层以下的短波辐射明显减少,所引起的热量垂向重新分配使得海水的层结增强、混合层变浅、上层海流辐散增强,进一步在赤道南北两侧产生异常向西的纬向流、赤道东太平洋的上升流增强,使得SST下降。但是这种冷却效应并未贯穿于全年,叶绿素对赤道东太平洋SST变化的影响呈现出明显的季节依赖性:在1~4月期间表现为SST增暖(即直接加热效应占主导作用);此后加热效应减弱,垂向冷平流的作用愈发强劲,间接动力冷却效应占主导。综合来看,叶绿素会使赤道东太平洋SST降低约0.5℃,并加强其季节变率。本文得到了叶绿素影响赤道东太平洋SST的两种不同的结果(变冷和变暖),这一发现为理解不同模式中叶绿素冷却或加热效应主导作用的差异提供了新的视角,为改进模式、合理表征叶绿素的影响提供了重要的科学依据。

计及区域建筑群生长特性的动态冷热负荷预测

考虑区域建筑群的动态生长特性,结合负荷计算理论、灰色Verhulst模型及等维新息灰色理论,采用MATLAB构建完整的区域动态冷热负荷预测方法,以常州高铁新城2017—2022年的建筑面积为历史数据,对区域未来10年的冷热负荷进行预测.结果表明,采用基于等维新息灰色理论的Verhulst灰色模型建立的3种业态面积预测方程拟合精度均达到一级.高铁新城未来10年冷热负荷先快速增长后缓慢增长直至饱和,达到饱和的时间约为2030年,冷、热负荷饱和规模分别为436、228 MW,与采用面积指标法的计算结果(冷负荷为472 MW、热负荷为285 MW)相比,分别降低了约7.52%、19.86%.

某区域能源项目燃气分布式能源系统经济性与运行策略分析

建筑领域的节能减排、能源结构转型是我国实现双碳目标的关键一环,多能互补耦合和高效利用的区域供能是实现城市建筑领域低碳发展的重要路径之一。天然气作为清洁优质的能源,是区域供能中能源结构调整的重要环节。燃气分布式能源系统(CCHP系统)可以充分实现能源的梯级利用,但燃气价格及电力价格等因素限制了其推广和发展。本文以某河水源热泵与CCHP系统耦合供能区域能源项目为研究对象,在湖南省现有燃气和电力价格基础上,对该项目CCHP系统不同运行策略下、不同容量的方案进行经济性比选分析,以确定最优容量和最佳运行方案,并提出CCHP系统经济性运行的气电价格比临界值,便于指导项目后续运行。

基于区域失效的数据中心和5G基站冷却设备可靠性预测方法研究

对数据中心和5G基站用冷却设备在不同安装区域的现场失效大数据进行分析,通过极大似然法建立寿命分布模型,其寿命分布最优拟合符合威布尔三参数分布规律,故障复发符合非齐次泊松过程,按区域聚类可靠性呈现显著性差异。对典型区域失效数据按可修复系统和不可修复系统分别进行可靠性预测,按可修复系统的预测结果与实际维修数据相关性良好。建立的基于区域失效的寿命分布、故障复发及可靠性预测方法适用于数据中心和5G基站用冷却设备的使用现场失效大数据分析,故障预测及维修备件、包修策略制定。

基于冰蓄冷系统的区域集中供冷工程造价管控研究

我国实施“双碳”战略后,集中供冷行业出现明显加速发展态势。集中供冷相较于中央空调,不仅高效节能,而且还有错峰降容、集约用地等优势。随着此类工程建设不断完善,其相应的工程造价管控也被政府相关部门及建设相关企业所重视。在国家鼓励推行低碳节能项目建设的总体要求下,文章基于冰蓄冷系统的区域集中供冷工程全过程造价管理重难点进行分析,以区域集中供冷工程造价控制案例作为研究对象,由浅入深地阐述其工程可研、设计、实施、结算等各个阶段造价管控的难点与对策分析;结合项目的特点及造价控制的实效,重点分析施工阶段的造价控制难点与对策,提高造价管控水平,有效控制工程造价。基于实际区域集中供冷工程造价管控及经验,分析相关控制重难点,并提出应对措施,其较好的造价控制效果为同类区域集中供冷工程造价管控方面提供参考。

极地钻井液冷却用板式换热器设计及换热性能模拟研究

在极地开展冰下基岩取心钻探,对研究冰下地质构造、揭示冰盖演化历史、评估未来气候变化等均有重要的意义。在极地冰下基岩钻探过程中,钻井液在孔底循环后温度可能升高至0℃以上,进而在上返过程中融化冰孔孔壁,导致井壁失稳,甚至引发卡钻事故。为此,有必要研发极地钻井液冷却系统,在地表将钻井液冷却至较低的温度后再注入孔内,进而使钻井液在循环过程中始终保持在0℃以下。换热器是钻井液冷却系统的核心部件。本文选用板式换热器做为钻井液的换热部件,采用平均温差法确定了板式换热器的换热面积和基本参数,然后使用COMSOL Multiphysics 6.0软件对板式换热器的换热性能进行了数值模拟。研究结果表明,该换热器可将钻井液冷却至-4~-3℃;此外,模拟结果表明,钻井液的出口温度随载冷剂注入温度的降低和载冷剂流量的增大而降低;钻井液的类型对换热器的换热性能有较大影响,而换热板片的材质对换热器的换热效果影响不大。

东北北部冷凉区免耕土壤的特性及作物效应

【目的】研究东北冷凉区免耕对土壤性状、作物产量的影响及其水土保持作用。【方法】利用平地和坡地9年长期定位田间试验,设置免耕和旋耕处理,系统监测土壤性状和作物产量。【结果】与传统旋耕相比,免耕下耕层土壤含水量提高3—5个百分点,110 cm土层储水量增加;10 cm处土壤温度降低2.1℃;0—15 cm土层有机质含量增加11%;土壤动物多样性增加;地表径流和土壤流失量分别减少90%和98%以上;玉米减产20%以上,大豆却增产10%左右;免耕在坡地上的效果好于平地。【结论】免耕对退化黑土恢复和水土保持作用显著,但冷凉区作物对免耕反应不同:大豆增产,玉米减产。因此,免耕适宜于大豆和坡耕地。