基于多孔网结构的斜温层储热罐性能改进数值模拟

[目的]为提升斜温层储热罐的储热性能,围绕斜温层储热罐内部结构优化问题开展研究.[方法]采用计算流体动力学方法,对常规结构、内置隔板结构和内置多孔网结构进行数值模拟和性能分析,获取流量对斜温层厚度和无量纲?损的影响规律,并研究不同黏性阻力系数下内置多孔网储热罐斜温层厚度的变化规律.[结果]多孔网结构储热罐中80℃的高温热水体积相比其他两种结构增加了15.38%;储热罐流量越大,斜温层厚度越大,无量纲?损越大;多孔网黏性阻力系数越大,斜温层厚度越小;流量为2.60 L/min时,内置多孔网储热罐的斜温层厚度相对于常规结构和内置隔板结构分别减小了31.58%和23.53%;内置多孔网储热罐的无量纲?损最低.[结论]多孔网储热罐储热性能优于常规结构和内置隔板结构储热罐,在储热罐中布置多孔网可以改善储热效果.

温跃层边界提取的组合算法

常用的几种温跃层边界提取方法的适用性有限。为进一步提高温跃层边界提取方法的适用性,该文提出一种用于海洋温跃层边界提取的组合算法,该算法基于调整判定阈值后的垂直梯度法和一种改进函数模型几何形态后的拟阶梯函数逼近法。为验证该算法对于温跃层边界提取的适用性、客观性,利用中国Argo实时资料中心发布的全球海洋Argo网格资料集(BOA_Argo),选取2018年夏季0◦∼30◦N、135◦E∼165◦E所在的太平洋区域的温度剖面数据进行处理。结果表明,该算法对低纬度海区温度剖面拟合质量较好,拟合均方根误差普遍低于1.3◦C,而且提取到的温跃层上下边界在纬向更平缓,然而对于中高纬度海区的温度剖面,组合算法处理效果不佳,直接通过垂直梯度法进行温跃层边界提取效果更好。

基于斜温层等效容积的大型蓄热罐动态特性分析

斜温层蓄热罐可以提高热电联产(combined heat and power,CHP)机组在供热期间的调峰能力,因此逐渐向大型化发展,但设计参数对蓄热罐的性能影响较大,且采用目前的性能评估方法效率较低。为此,建立大型蓄热罐的物理模型及数学模型,研究蓄热过程中斜温层的形成及变化过程,提出斜温层等效容积的概念,同时分析结构参数及运行参数对斜温层等效容积的影响。结果表明:形成稳定斜温层后,随着蓄热量的增加,斜温层厚度变化不大,采用斜温层等效容积可以更高效的评估蓄热罐的性能。比较不同工况下蓄热罐等效容积的相对变化量可知,不同影响因素对斜温层等效容积的影响从高到低排序依次为布水器布置、蓄热流量、高径比和冷热水温差。研究成果为大型蓄热罐的性能评估提供了一种新参考。

赤道印度洋中部沉降颗粒物的季节变化特征及调控机制研究

基于2020年1—12月在赤道印度洋中部海域获取的沉积物捕获器时间序列样品,分析了沉降颗粒物与颗粒有机碳(particulate organic carbon,POC)通量的季节变化特征,并结合卫星遥感、数值模式及再分析数据探究上层物理过程对生物泵输出通量的调控作用。结果表明,2020年赤道印度洋中部海域的沉降颗粒物总通量与颗粒有机碳通量的变化范围分别为4.57~35.75 mg/(m^(2)·d)[(18.94±10.18)mg/(m^(2)·d)]和0.27~2.97 mg/(m^(2)·d)[(1.09±0.66)mg/(m^(2)·d)],两者均呈现显著的季节变化特征。总体上,1—3月、6月和9—11月呈现出3个显著的高通量事件。通过分析发现混合层深度变化与营养盐跃层波动的耦合作用可能是调控中深层通量变化的主要原因。与此同时,西南季风流(Southwest Monsoon Current,SMC)与赤道Wyrtki急流生消也可能通过改变温跃层或营养盐跃层深度对沉降颗粒物通量强度和季节变化起调控作用。

广西壮族自治区博物馆扩建部分结构设计

广西壮族自治区博物馆扩建部分是一座框架结构的公共建筑,结构存在结构超长、扭转不规则、长悬挑以及大跨度等设计难点。采用YJK软件建立计算模型进行方案比选,确定了结构体系和基础方案,各项指标满足现行规范要求。针对本工程的结构设计难点,采取相对应的设计措施,保证结构的安全可靠。本项目的设计及分析过程可为类似结构的设计提供参考。

2013-2020年太平洋快速增暖现象的辨识与时空特征研究

利用基于Argo的多套次表层温盐观测数据,本文分析了2004-2020年太平洋0~1500 m海洋热含量的变化趋势。研究发现,太平洋海洋热含量在2013年出现长期趋势的转变。2013-2020年太平洋海洋热含量相对于2004-2012年快速增加,前者线性趋势达到约0.50×10^(22)J/a,显著高于后者。近期太平洋出现了快速增暖现象。2013-2020年间,太平洋海洋热含量线性增加趋势最大出现在北太平洋西部,其次是热带太平洋和北太平洋东部,而整个南太平洋海洋热含量呈略微减少趋势。在北太平洋西部,海洋热含量快速增加集中在黑潮延伸体海域,该增暖趋势很可能是由黑潮延伸体主轴北移引起的。值得一提的是,日本以南出现了局地海洋热含量减少趋势,该变冷趋势与黑潮大弯曲不断加深有关。在增暖趋势次之的热带太平洋,海洋热含量的快速增加很可能是由温跃层快速加深导致的。此外,太平洋快速增暖反映在海表高度快速升高之中。1 cm/a的海表高度线性趋势对应于0.11×10^(9)J/(m^(2)·a)的海洋热含量线性趋势。本研究揭示了全球变暖停滞结束以来太平洋快速增暖现象,加深了对近期太平洋热力状况的认识。

基于相变储热的油田井场新型加热装置

在我国“双碳”目标与路径要求下,提升能源利用效率是实现低碳发展的重要方式之一。相变储热技术利用谷电时加热相变材料储能,峰电时放热加热采出液,利用峰谷电价差节约加热电费。以某国有大型油田企业为例,针对井场电加热运行成本较高的问题,开发了油田井场专用高效水-石蜡联合储热装置,设计了以采出液低温输送为导向的自适应相变储热控制系统,为油田企业的节能降本和绿色企业创建提供技术支撑。

DYNAMIC CHARACTERISTICS OF SEASONAL THERMOCLINE IN THE DEEP SEA REGION OF THE SOUTH CHINA SEA

The dynamic characteristics of the seasonal thermocline in the deep sea region of the South China Sea were analyzed by using seasonal mean temperature climatology. The thermocline undergoes remarkably seasonal variation throughout a year, is thinnest and weakest in winter, and thickest in spring, strongest in summer and fall. Due to the upper Ekman transport caused by monsoon over the SCS, the thermocline slopes upward(downward) in winter(summer) from northwest to southeast, but there is no pileup of upper warm water along the monsoon direction. In addition, the intrusion of the Kuroshio loop through the Luzon Strait, and some local eddies in the SCS, can notably affect the depth, thickness and strength of the thermocline in the deep sea region of the SCS.

Analysis of interdecadal variation of tropical Pacific thermocline based on assimilated data

The interdecadal variation of Pacific thermocline represented by depth anomalies of 25σθ isopycnal surface calculated from SODA data set is analyzed. The climatological depth of 25σθ isopycnal surface is quite close to the depth of 20 ℃ isotherm in the tropical Pacific. The EOF1 mode of the 25σθ isopycnal surface accounts for 26. 4% of the total variance and its associated pattern is of east-west direction. The centers of positive and negative extremes are located near 10oS over the southern Pacific and the correlation coefficient with zero-lag between the corresponding EOF1 time coefficient and PDO index is -0.67. This shows that there is very close relation between the southern tropical Pacific and PDO. The wavelet analysis of detrended EOF1 time coefficient reveals that there are two dominant time scales of about 3～7 and 30 a respectively. An apparent abruptness of mean value occurred in the late 1970s. EOF2 mode accounts for 12.4% of the total variance and its pattern is an ENSO-related one. The correlation coefficient between the EOF2 time coefficient and NINO3 index is -0.68. The wavelet analysis of EOF2 time coefficient reveals that there are two leading time scales of about 2～7 and 10～15 a respectively. On an interdecadal scale, the zonal change is consistent along the equator and is seesaw along 10oS; there is consistent polarity in the tropics along 165oE, but reverse polarity between around equator and other tropical region along 120oW. In all the four profiles mentioned above, the regime shift occurred in the late 1970s. The evolving characteristics of anomalies can be explained mostly by the anomalies of ocean currents during a complete cycle on an interdecadal scale.

A numerical study on seasonal variations of the thermocline in the South China Sea based on the ROMS

On the basis of the regional ocean modeling system （ROMS）, the seasonal variations of the thermocline in the South China Sea （SCS） were numerically investigated. The simulated hydrodynamics are in accordance with previous studies： the circulation pattern in the SCS is cyclonic in winter and anticyclonic in summer, and such a change is mostly driven by the monsoon winds. The errors between the modeled temperature profiles and the observations obtained by cruises are quite small in the upper layers of the ocean, indicating that the ocean status is reasonably simulated. On the basis of the shapes of the vertical temperature profiles, five thermocline types （shallow thermocline, deep thermocline, hybrid thermocline, double thermocline, and multiple thermocline） are defined herein. In winter, when the northeasterly monsoon prevails, most shallow shelf seas in the northwest of the SCS are well mixed, and there is no obvious thermocline. The deep region generally has a deep thermocline, and the hybrid or double thermocline often occurs in the areas near the cold eddy in the south of the SCS. In summer, when the southwesterly monsoon prevails, the shelf sea area with a shallow thermocline greatly expands. The distribution of different thermocline types shows a relationship with ocean bathymetry： from shallow to deep waters, the thermocline types generally change from shallow or hybrid to deep thermocline, and the double or multiple thermocline usually occurs in the steep regions. The seasonal variations of the three major thermocline characteristics （the upper bound depth, thickness, and intensity） are also discussed. Since the SCS is also an area where tropical cyclones frequently occur, the response of thermocline to a typhoon process in a short time scale is also analyzed.

Interannual Thermocline Signals and El Nio-La Nia Turnabout in the Tropical Pacific Ocean

One of the fundamental questions concerning the nature and prediction of the oceanic states in the equatorial eastern Pacific is how the turnabout from a cold water state （La Nino） to a warm water state （El Nino） takes place, and vice versa. Recent studies show that this turnabout is directly linked to the interannual thermocline variations in the tropical Pacific Ocean basin. An index, as an indicator and precursor to describe interannual thermocline variations and the turnabout of oceanic states in our previous paper （Qian and Hu, 2005）, is also used in this study. The index, which shows the maximum subsurface temperature anomaly （MSTA）, is derived from the monthly 21-year （1980-2000） expendable XBT dataset in the present study. Results show that the MSTA can be used as a precursor for the occurrences of E1 Nino （or La Nino） events. The subsequent analyses of the MSTA propagations in the tropical Pacific suggest a one-year potential predictability for E1 Nino and La Nino events by identifying ocean temperature anomalies in the thermocline of the western Pacific Ocean. It also suggests that a closed route cycle with the strongest signal propagation is identified only in the tropical North Pacific Ocean. A positive （or negative） MSTA signal may travel from the western equatorial Pacific to the eastern equatorial Pacific with the strongest signal along the equator. This signal turns northward along the tropical eastern boundary of the basin and then moves westward along the north side of off-equator around 16°N. Finally, the signal returns toward the equator along the western boundary of the basin. The turnabout time from an E1 Nino event to a La Nino event in the eastern equatorial Pacific depends critically on the speed of the signal traveling along the closed route, and it usually needs about 4 years. This finding may help to predict the occurrence of the E1 Nino or La Nino event at least one year in advance.

A dipole mode at thermocline layer in the tropical Indian Ocean

Temperature data at different layers of the past 45 years were studied and we found adiploe mode in the thermocline layer (DMT): anomalously cold sea temperature off the coast of Sumatra and warm sea temperature in the western Indian Ocean. First, we analyzed the temperature and the temperature anomaly (TA) along the equatorial Indian Ocean in different layers. This shows that stronger cold and warm TA signals appeared at subsurface than at the surface in the tropical Indian O-cean. This result shows that there may be a strong dipole mode pattern in the subsurface tropical Indian Ocean. Secondly we used Empirical Orthogonal Functions (EOF) to analyze the TA at thermocline layer. The first EOF pattern was a dipole mode pattern. Finally we analyzed the correlations between DMT and surface tropical dipole mode (SDM), DMT and Nino 3 SSTA, etc. and these correlations are strong.

The Southwest Indian Ocean Thermocline Dome in CMIP5 Models:Historical Simulation and Future Projection

Using 20 models of the Coupled Model Intercomparison Project Phase 5 （CMIP5）, the simulation of the Southwest Indian Ocean （SWIO） thermocline dome is evaluated and its role in shaping the Indian Ocean Basin （IOB） mode following E1 Nifio investigated. In most of the CMIP5 models, due to an easterly wind bias along the equator, the simulated SWIO thermocline is too deep, which could further influence the amplitude of the interannual IOB mode. A model with a shallow （deep） thermocline dome tends to simulate a strong （weak） IOB mode, including key attributes such as the SWIO SST warming, antisymmetric pattern during boreal spring, and second North Indian Ocean warming during boreal summer. Under global warming, the thermocline dome deepens with the easterly wind trend along the equator in most of the models. However, the IOB amplitude does not follow such a change of the SWIO thermocline among the models; rather, it follows future changes in both ENSO forcing and local convection feedback, suggesting a decreasing effect of the deepening SWIO thermocline dome on the change in the IOB mode in the future.

Analysis of monthly variability of thermocline in the South China Sea

This study analyzes monthly variability of thermocline and its mechanism in the South China Sea(SCS). The study is based on 51-year(1960–2010) monthly seawater temperature and surface wind stress data from Simple Ocean Data Assimilation(SODA), together with heat flux, precipitation and evaporation data from the National Centers for Environmental Prediction(NCEP), the National Oceanic and Atmospheric Administration(NOAA) and the Woods Hole Oceanographic Institution, respectively. The results reveal that the upper boundary depth(Z_(up)), lower boundary depth(Z _(low)), thickness(?Z) and intensity( T _z) of thermocline in the SCS show remarkable monthly variability. Being averaged for the deep basin of SCS, Z_(up) deepens gradually from May to the following January and then shoals from February to May, while Z low varies little throughout the whole year. Further diagnostics indicates that the monthly variability of Z_(up) is mainly caused by the buoyancy flux and wind stress curl. Using a linear method, the impacts of the buoyancy flux and wind stress curl on Z_(up) can be quantitatively distinguished. The results suggest that Z_(up) tends to deepen about 4.6 m when the buoyancy flux increases by 1×10^(-5) kg/(m?s ~3), while it shoals about 2.5 m when the wind stress curl strengthens by 1×10-^(7) N/m3.

Review on Thermocline Storage Effectiveness for Concentrating Solar Power Plant

In this paper, a literature review on thermocline storage performance for Concentrating Solar Power (CSP) plant storage systems has been conducted. The efficiency of materials to store heat depends on the storage process like sensible heat storage, latent heat storage and thermochemical one and also on their properties. This study has been focused on sensible heat storage materials especially thermocline storage system (DMT) using eco-materials which has a high potentiality (35%) to reduce CSP cost. There is a possibility to use natural rocks, industry waste and to develop also materials for a thermocline storage within a bed called packed bed using one tank. The thermal storage materials should have some optimum parameters (particle diameter less than 2 cm and good thermo-physical properties) to achieve better thermal storage performance (thermal cycle efficiency, extraction factor). However, the size and the shape of natural rocks are uncontrollable (big diameter) and can drive to thermocline degradation, catastrophic thermal ratcheting and poor thermal stratification due to the variability of the storage system porosity and the stress on the storage tank wall. Also a better thermal storage efficiency is achievable at low velocity and with good thermo-physical properties of the HTF. The ratio H/D, the height, the porosity, the shape and the position of the tank should be optimized to increase the storage efficiency.

Thermocline Model for Estimating Argo Sea Surface Temperature Thermocline Model for Estimating Argo Sea Surface Temperature

Argo has become an important constituent of the global ocean observation system.However,due to the lack of sea surface measurements from most Argo profiles,the application of Argo data is still limited.In this study,a thermocline model was constructed based on three key thermocline parameters,i.e,thermocline upper depth,the thermocline bottom depth,and thermocline temperature gradient.Following the model,we estimated the sea surface temperature of Argo profiles by providing the relationship between sea surface and subsurface temperature.We tested the effectiveness of our proposed model using statistical analysis and by comparing the sea surface temperature with the results obtained from traditional methods and in situ observations in the Pacific Ocean.The root mean square errors of results obtained from thermocline model were found to be significantly reduced compared to the extrapolation results and satellite retrieved temperature results.The correlation coefficient between the estimation result and in situ observation was 0.967.Argo surface temperature,estimated by the thermocline model,has been theoretically proved to be reliable.Thus,our model generates theoretically feasible data present the mesoscale phenomenon in more detail.Overall,this study compensates for the lack surface observation of Argo,and provides a new tool to establish complete Argo data sets.

Variations of SST and Thermocline Depth in the Tropical Indian Ocean During Indian Ocean Dipole Events

Interannual variations in the surface and subsurface tropical Indian Ocean were studied using HadISST and SODA data-sets.Wind and heat flux datasets were used to discuss the mechanisms for these variations.Our results indicate that the surface andsubsurface variations of the tropical Indian Ocean during Indian Ocean Dipole(IOD)events are significantly different.A prominentcharacteristic of the eastern pole is the SSTA rebound after a cooling process,which does not take place at the subsurface layer.Inthe western pole,the surface anomalies last longer than the subsurface anomalies.The subsurface anomalies are strongly correlatedwith ENSO,while the relationship between the surface anomalies and ENSO is much weaker.And the subsurface anomalies of thetwo poles are negatively correlated while they are positively correlated at the surface layer.The wind and surface heat flux analysissuggests that the thermocline depth variations are mainly determined by wind stress fields,while the heat flux effect is important onSST.

Exploring thermocline and water masses variability in southern South China Sea from the World Ocean Database(WOD)

Study about water characteristics(temperature and salinity) from the World Ocean Database(WOD) was conducted in the area of southern South China Sea(SSCS), covering the area of 0°–10°N, 100°–117°E. From interannual analysis, upper layer(10 m) and deep water temperature(50 m) increased from 1951 until 2014. Monthly averaged show that May recorded the highest upper layer temperature while January recorded the lowest. It was different for the deep water which recorded the highest value in September and lowest in February. Contour plot for upper layer temperature in the study area shows presence of thermal front of cold water at southern part of Vietnam tip especially during peak northeast season(December–January). The appearances of warm water were obviously seen during generating southwest monsoon(May–June). Thermocline study revealed the deepest isothermal layer depth(ILD) during peak northeast and southwest monsoon. Temperature threshold at shallow area reach more than 0.8°C during the transitional period. Water mass study described T-S profile based on particular region. Water mass during the southwest monsoon is typically well mixed compared to other seasons while strong separation according to location is very clear. During transitional period between northeast monsoon to southwest monsoon, the increasing of water temperature can be seen at Continental Shelf Water(CSW) which tend to be higher than 29°C and vice versa condition during transitional period between southwest monsoon to northeast monsoon. Dispersion of T-S profile can be seen during southwest monsoon inside Tropical Surface Water(TSW) where the salinity and temperature become higher than during northeast monsoon.

EFFECTS OF A SLOPING THERMOCLINE AND RAYLEIGH FRICTION ON EQUATORIALLY TRAPPED KELVIN WAVES

Based on the observed equatorial ocean dynamic characteristics, the effects of a sloping thermocline and Rayleigh friction on the equatorially trapped free Kelvin waves were theoretically studied with a linear one and one half layer reduced gravity model, the multiple scale method and a small parameter expansion technique. Assuming that main thermocline depth (MTD) variations are slow, i.e. the changes of MTD over one wavelength are smaller than that of the wave amplitude and that wave reflections are negligible, the authors showed by their analytical results that the wavelengths and amplitudes of Kelvin waves are significantly modified by the MTD variations and Rayleigh friction. The results also showed that for an eastward shallowing thermocline, the zonal velocity of the Kelvin waves varies with thermocline depth to the power -7/8. The eastward shallowing of the thermocline depth strengthens Kelvin wave entrapment at the equator. Rayleigh friction reduces the Kelvin wave’s eastward velocity while the thermocline acts in the opposite way. The friction causes dispersion of the Kelvin wave, whose dissipation factor does not depend on its wavelength. The friction increases the lateral decay length and causes phase lines of Kelvin waves to slant westward in parabolic arcs.

A THREE-DIMENSIONAL THERMOCLINE MODEL FOR THE YELLOW SEA AND NORTHERN EAST CHINA SEA

A time-dependent, three-dimensional finite difference model is presented for simulating the stratifiedYellow Sea and northem East China Sea. The mode is forced by time-dependent observed wind, surfaceflux of heat, and tidal turbulence. With this model, momentum and temperature distribution can be computed,and an approximation for the sub-grid scale effects is introduced by the use of mass and momentumexchange coefficients. The vertical exchanges are quite dependent on these assumed coefficents, whichare complicated functions of the turbulence energy of tide and wind, of the stratified strength and otherfactors. This model was applied to describe the mechanics of the variations in strength and thickness ofthe thermocline covering almost the whole Yellow Sea and northern East Chna Sea in summer. Comparisonsof the computed output with obtained survey data led to some important conclusions.