Improved spatial resolution in soil moisture retrieval at arid mining area using apparent thermal inertia

A surface soil moisture model with improved spatial resolution was developed using remotely sensed apparent thermal inertia（ATI）.The model integrates the surface temperature derived from TM/ETM＋ image and the mean surface temperature from MODIS images to improve the spatial resolution of soil temperature difference based on the heat conduction equation,which is necessary to calculate the ATI.Consequently,the spatial resolution of ATI and SMC can be enhanced from 1 km to 120 m（TM） or 60m（ETM＋）.Moreover,the enhanced ATI has a much stronger correlation coefficient（R^2） with SMC（0.789） than the surface reflectance（0.108） or the ATI derived only from MODIS images（0.264）.Based on the regression statistics of the field SMC measurement and enhanced ATI,a linear regression model with an RMS error of 1.90%was found.

Investigating spatial and temporal variations of soil moisture content in an arid mining area using an improved thermal inertia model

Mining operations can usually lead to environmental deteriorations. Underground mining activities could cause an extensive decrease in groundwater level and thus a dramatic variation in soil moisture content（SMC）. In this study, the spatial and temporal variations of SMC from 2001 to 2015 at two spatial scales（i.e., the Shendong coal mining area and the Daliuta Coal Mine） were analyzed using an improved thermal inertia model with a long-term series of Landsat TM/OLI（TM=Thematic Mapper and OLI=Operational Land Imager） data. Our results show that at large spatial scale（the Shendong coal mining area）, underground mining activities had insignificant negative impacts on SMC and that at small spatial scale（the Daliuta Coal Mine）, underground mining activities had significant negative impacts on SMC. Trend analysis of SMC demonstrated that areas with decreasing trend of SMC were mainly distributed in the mined area, indicating that underground mining is a primary cause for the drying trend in the mining region in this arid environment.

Thermal inertia at the MSL and InSight mission sites on Mars

For planetary surface materials,thermal inertia is the critical property that governs the surface’s daily thermal response and controls diurnal and seasonal surface temperature variations.Here we use the ground measurements made by the MSL Curiosity rover and the InSight lander to determine the thermal inertia of two sites on Mars.This study compares the variation of thermal inertia during and after the Large Dust Storm(LDS)of Martian Year(MY)34.To determine surface thermal inertia,we derive a simple approximation(using energy balance),which utilizes surface albedo,surface energy flux,and diurnal change in the surface temperature.The average thermal inertia in MY34 is about 39.2%,3.7%,and 3.4%higher than MY35 average thermal inertia for the MSL,InSight(FOV1),and InSight(FOV2),respectively.Notably,the thermal inertia at the InSight(FOV1)is consistently lower by about 20 J·m^(-2)·s^(-1/2)·K^(-1) than the InSight(FOV2)site for all scenarios,indicating variation in the region’s surface composition.The best-fit surface albedo in MY34(determined using the KRC model)are about 0.08,0.05,and 0.03 higher than MY35 surface albedo for the MSL,InSight(FOV1),and InSight(FOV2),respectively.An increase in both surface albedo and thermal inertia during the LDS indicates that the underlying surface is both more thermally resistant and more reflective than the overlying loose dust.

The Thermal Inertia Characteristics of the System Ocean-Atmosphere

To estimate the time delay between the planetary temperature change and the change of the incoming solar radiation fraction absorbed by the ocean and the atmosphere, the analytical energy balance model is presented. The model generalization allows of using averaged data for model parameterization. Using the model, the time delay is investigated on four model cases of absorbed radiation change. The interconnections among the time delay, the planetary thermal inertia and the ocean active layer depth are established.

A Reliability Assessment of an Integrated Energy System Based on Coupling Energy Flow and Thermal Inertia

With the wide application of integrated energy systems(IES),the degree of coupling between different types of energy sources is further strengthened,and the mechanism of fault development tends to be complicated.Therefore,in order to improve the accuracy and practicability of the reliability assessment of IESs,a sequential simulation reliability assessment method considering multi-energy flow and thermal inertia is proposed in this paper.In this method,the IES structure model is constructed with the combined cooling,heating and power(CCHP)unit as the core equipment,combining with the new energy source to realize the comprehensive energy power flow calculation considering any loss.Then,a load reduction optimization model is established,considering the importance of load and operational economy,in the system status analysis.Furthermore,the heat supply reliability index is corrected taking into account the transmission delay characteristics and terminal thermal inertia.A case study based on the 20-node and the analysis of the influence factors demonstrates the validity of the proposed method.

Thermal Inertia of 330 MW Circulating Fluidized Bed Boiler during Load Change

The operating principles of Circulating Fluidized Bed(CFB)boilers involve a significant amount of heat accumulation,which forms the thermal inertia of the boiler and hinders the improvement of its variable load response rate.This study aims to characterize the thermal inertia of CFB boilers by evaluating the change in the boiler's heat accumulation corresponding to the change in unit power generation.The thermal inertia of a 330MW CFB boiler was determined through the collection of operating data under four different operating conditions of 30%,50%,75%,and 100%load.The study proposes to substitute the existing refractory material with a metal grille to reduce the thermal inertia of the boiler.The effect of the metal grille on heat transfer was confirmed through verification on a 440 t/h CFB boiler,and its performance change and thermal inertia reduction were further predicted.The results indicate that over 50%of the total thermal inertia of CFB boilers originates from the refractory material.The use of metal grille in place of refractory material improved heat transfer in the furnace,resulting in a decrease of the furnace chamber temperature by 13℃in the 330 MW CFB boiler.This reduction of thermal inertia by 30%-35%will facilitate faster load lifting and lowering of the boiler,fulfilling the requirement for flexible peaking.

INNOVATIVE FAÇADES Lightweight and Thin Systems with High Inertia for the Thermal Comfort Application in Office Buildings in Southern Europe

ABSTRACT This research demonstrates that lightweight,thin façade systems with innovative materials can combine a higher thermal inertia with a lower energy demand for heating and cooling as compared to massive façades.It is therefore very possible to use innovative light materials(originally developed in and for Central Europe)also in Southern Europe,where the main problem is the energy demand for cooling in summer(in contrast to the energy demand for heating in northern latitudes).Three of those systems were selected and investigated for three different climatic conditions in middle latitudes with respect not only to static energy performance parameters imposed by the Italian legislation(thermal transmittance U and superficial mass M_(S)),but also checking two dynamic energy performance parameters defined particularly for non massive structures(phase delay f_(a) and decrement factorφ).Additionally a recently introduced by European standard UNI-EN-ISO-13786 parameter(periodic thermal transmittance Y_(ia))was considered.Verification of the energy performance of the façade systems was performed using thermodynamic simulations.The results are:•Development and application of an experimental/simulation procedure for the evaluation of the thermal performance of façade systems in use(annual energy demand:[kWh],costs[€]and.CO_(2) produced[kg]).•Demonstration that energy performance of new lightweight systems is better than the one of a traditional Italian reference façade system with high MS.•Proposal of possibilities for improving the analyzed façade systems with respect to their application in middle latitudes.•Development of design criteria for the application of the analyzed façades in three climatic zones in Italy.

A remote sensing model for monitoring soil evaporation based on differential thermal inertia and its validation

The presently applied remote sensing algorithms and approaches to monitor soil surface fluxes are reviewed at the beginning of this paper, and the bottleneck of the estimation of soil sur-face fluxes lies in the dependence on non remotely sensed parameters (NRSP). A soil surface evaporation model based on differential thermal inertia, only using remotely sensed information, has thus been proposed after many experiments. The key of the model is to derive soil moisture availability by differential thermal inertia rather than local soil parameters such as soil properties and type. Bowen ratio is estimated by means of soil moisture availability instead of NRSP, such as temperature and wind velocity. Net radiation flux and apparent thermal inertia have been used for soil heat flux parameterization, therefore, the objective of evaporation (latent heat flux) inversion for bare soil only by remotely sensed information can be realized. Two NOAA-AVHRR five-band images, taken at Shapotou northwest of China when soil surface temperature approximated to the highest and lowest of the region, were applied in combination with the ground surface information measured synchronously. The distribution of soil evaporation in Shapotou could be determined. Model verification has been performed between the measured soil surface evaporation and the corresponding calculated value of the images, and the result has proved model to be feasible. Fi-nally, the possible errors and further modifications when applying model to fulling vegetation can-opy have been discussed.

Experimental Study of the Thermal Behavior of a Bioclimatic Building Prototype in a Sahelian Zone

Buildings constructed with modern materials (cement blocks, sheet metal, reinforced concrete, etc.) in the Sahelian zone often generate excessive electricity consumption and consequently very high electricity bills. This study is a contribution to the development of new building types based on the principle of bioclimatic construction. The aim is to find materials suited to the Sahelian climate and improve thermal comfort. To this end, an experimental study of the hygrothermal behavior of a bioclimatic building prototype with a domed roof is being carried out. Site meteorological data, air temperature and relative humidity of the building’s internal environment were measured for three climatic seasons in Burkina Faso. The data acquisition system consists of thermocouples, solarimeters and humidity meters, and the data are processed using Excel and Origin Pro software. The results show that, despite the high temperature values (between 36˚C and 39˚C) of the internal environment measured in the hot season, good thermal performance is achieved, in particular an average phase shift of 7.17 h and an average damping of 10.81˚C. The dome-roofed building could therefore contribute to limiting heat transmission to the building interior, improving thermal comfort all year round. Analysis of humidity profiles shows that indoor humidity varies between 66% and 80% for the September period, and between 44% and 69% for the January period. The high values of internal ambient humidity could be reduced by very good ventilation of the building. This study shows that the proposed bioclimatic building prototype with domed roof could be integrated into the Sahelian habitat.

A REMOTE-SENSING THERMAL INERTIA MODEL FOR SOIL MOISTURE AND ITS APPLICATION

Ⅰ. INTRODUCTION Information of soil water content plays a very important role in agriculture, water conservancy, meteorology and so on. However, regional distribution for soil water content is not even. Remote sensing for estimating regional soil moisture is very suitable. Particularly, the thermal inertia remote sensing in thermal infrared waveband is realistic and efficient.

A new measuring technique of soil thermal inertia

Thermal inertia is the function of substance density, heat capacity and heat diffusivity, and is an important parameter for researching the process of surface heat balance using remote sensing technique. In this paper, using soil heat plates, infrared thermometer, data logger and other instruments, by man-controlled changing the solar radiation status on the soil samples, the authors gave a new method to measure soil thermal inertia. Using the continuously surveying data of soil heat flux and infrared radiation temperature, thermal inertia can be calculated easily. Based on the thermal inertia calculation of three soil samples with different water content, good results were abtained by the authors, so this method is feasible. Meanwhile, this measuring technique is also a new attempt.

Study of Construction Techniques and Hygro-Thermal Behavior of a Vernacular Earth Building in a Humid Tropical Climate

This study analyzes the know-how of local communities, to draw on techniques that make contemporary buildings more energy efficient. The impluvium hut in the locality of Enampore, Casamance, Southern Senegal, served as the object of study. The hut, including several rooms, is entirely built with earthen walls, earthen floor, earthen ceiling, covered by a double straw roof and its central courtyard. A room noted (L) and a semi-opened living space were chosen as spaces for hygro-thermal experimentation. The hottest average temperature obtained respectively in the room (L) and in the living space is 25.5˚C and 27˚C when outside is about 34˚C. The thermal amplitude inside room (L) is 0.88˚C, in semi-opened living space, is 2.6˚C and outside is 9.5˚C. With these results we can say that room (L) undergoes very low temperature variations and that there is no need to air-condition in the enclosure. The thermal amplitude makes it possible to see the influence of the earthen walls on the interior temperature and its regularity compared to the fluctuation of the external temperature. The thermal inertia of the building walls was characterized using also the time lag and the decrement factor. They was respectively 7.0 H and 0.093 for the room (L). With this result we can say that this material has a high thermal inertia. For humidity, it is high around 78.5% in the room (L), 66.0% at the semi-open living room, when it is 59.0% outside. Through this study, it is possible that the revalorization of vernacular architecture can be an alternative to reduce the energy consumption of buildings.

Finite element simulation of inertia friction welding of superalloy bars

A thermo-mechanical coupling.finite element model was built to investigate the inertia friction welding of GH4169 bars. The remeshing and map solution techniques were adopted. Ttle whole welding process was investigated by adopting an innovative heat generation model and the flywheel rotational speed measured via the experiment. The simulated evolution of axial shortening shows a good agreement with the experiment. In addition, extensive .strain concentration presents in the interface and flash, and the largest ,strain exists near the flash root. Moreover, an intere.sting thermal reflux phenomenon during the cooling stage was found.

集成差异化建筑集群的微网系统分层分布式优化调度

针对差异化绝热性能建筑集群与微网系统间的协同互动,提出一种基于交替方向乘子法(ADMM)的分层分布式优化调度策略,在实现微网高效、经济运行的同时,充分考虑不同建筑集群的差异化利益诉求和隐私保护需求。首先,考虑多主体利益诉求,构建了集成差异化绝热性能建筑集群的微网系统分层调度模型。在上层,微网系统运营商(MSO)通过优化购电功率、售电功率和售电价格,最大化其收益;在下层,采用热阻-热容网络对建筑的热动态过程进行差异化建模,建筑集群用户通过优化暖通空调系统送风温度和购电价格,最小化其用能成本。然后,考虑数据隐私性需求,采用ADMM进行分层分布式求解。通过引入虚拟变量拆分上层MSO和下层建筑集群用户子问题,并耦合上下层优化变量,根据ADMM进行局部更新和交替迭代,得到全局优化解。为确保算法的收敛性,利用McCormick包络松弛方法将子问题转化为凸优化。最后,通过算例分析验证了分层分布式优化调度策略的合理性和有效性。

考虑建筑物热惯性的综合能源系统主从博弈协调优化策略

从用户角度出发,提出一种考虑建筑物热惯性的综合能源系统主从博弈协调优化策略。首先,建立热网特性模型和建筑物热惯性模型,并构建以微网运营商为领导者,用户为跟随者的主从博弈数学模型。在光伏出力大时,用户通过电制热设备将电能转化为热能,并利用建筑物热惯性将热能加以存储,无需将光伏余电尽数售给微网运营商,可增强用户权益,同时可有效避免大量光伏余电接入电网,进而缓和余电上网的压力。其次,考虑用户用能满意度及温度舒适度,建立微网运营商与用户的定价、定量模型,并证明Stackelberg博弈均衡解的存在性与唯一性。最后通过算例验证所提策略的有效性,极大地增强了用户权益,同时避免用户光伏余电大量接入电网。

汽车尾气温差发电系统瞬态回收性能分析

为了预测温差发电(thermoelectric generator, TEG)系统的动态特性,基于COMSOL Multiphy-sics建立了用于求解温差发电系统温度场分布的瞬态计算流体力学(computational fluid dynamics, CFD)模型和用于研究温差发电模块瞬态响应特性的分析模型,提出了混合瞬态CFD-分析模型,并经过瞬态试验验证.结果表明:由于热惯性的影响,TEG系统的转化效率会出现一个瞬时的较高值;相较于尾气温度和质量流量的瞬态波动,热电半导体的热端温度和冷端温度会存在时滞;在美国环保局的高速公路燃油经济性测试(highway fuel economy test, HWFET)模式循环工况下,瞬态模型求解得到整个温差发电系统的平均输出功率、平均转化效率分别为35.63 W和3.40%,瞬态模型的输出电压平均误差为6.41%;该模型能够以较高的精度及较短的计算时间预测温差发电系统在瞬态热源激励下的瞬态响应特性.

计及最小惯量约束的风光火储联合系统优化调度

风、光、储多种新能源并网使系统常常处在低惯量运行场景下,给考虑频率稳定的系统优化调度带来极大挑战。为此提出了一种计及最小惯量约束的多源联合电力系统优化调度模型。首先,综合考虑两项频率指标,计算满足频率指标的系统最小惯量需求,将非线性的频率稳定约束转化为线性的最小惯量约束加入调度模型之中。其次,利用含模糊参数的机会约束表达源荷不确定性对于联合系统的影响,建立模糊参数下的系统优化调度模型。最后,通过IEEE 30节点系统验证了该模型的经济性与安全性。

考虑热惯性的极端冰雪灾害下综合能源系统韧性提升

近年来,极端冰雪灾害导致配电网大规模停电事故频发,严重危害到人民群众的冷暖安危。目前,综合能源系统中热电耦合密切,极端冰雪灾害发生时如何通过热能提升电力系统韧性依然面临挑战。为提升综合能源系统应对极端冰雪灾害的能力,充分发挥热能特性,首先,文中提出了极端冰雪灾害下配电网线路的故障模型;其次,结合热网传输延时特性和热负荷的热惯性,对综合能源系统进行建模;然后,基于两阶段分布鲁棒优化模型提出了灾前利用建筑物热惯性存储热能、配置储热量,灾后闭合联络开关、优化故障抢修的综合能源系统韧性提升策略;最后,搭建热电耦合算例进行仿真验证。结果表明,所提韧性提升策略能够充分挖掘热能潜力,兼顾了经济性和鲁棒性,实现了综合能源系统韧性提升。

含相变储能热泵的综合能源系统优化调度

利用相变储能装置的储能特性,针对热量传输过程中的热延迟与热衰减,建立考虑热惯性特征的含相变储能热泵的综合能源系统优化调度模型,并采用预测平均评价(predicted mean vote, PMV)指标来量化热负荷弹性。运用Dymola与Matlab联合建模,以经济运行总成本为目标函数,对比分析三种不同场景下综合能源系统的削峰填谷能力、可再生能源消纳能力、环境效益与安全性,对冬季典型日进行24 h运行策略优化。算例分析结果表明,考虑热惯性与热负荷弹性的含相变储能热泵的综合能源系统具有更好的经济性与抗故障能力,相较于含常规储热水箱的综合能源系统经济运行总成本降低了6.6%,抗供热故障时间延长3.51 h。

交直流电力系统与供热系统联合经济调度

随着热电联产等技术的广泛应用,电力系统和供热系统耦合日益紧密,电热联合调度得到了广泛的关注,但现有电热联合调度忽略了热网供电来源的多样性,由此提出了交直流电力系统与供热系统联合经济调度方法。首先,建立交直流电力系统模型,并提出一种线性近似方法对电压源变换器模型所带来的强非线性进行处理;然后,以运行成本最低为目标,建立考虑热网热惯性的交直流电力系统与供热系统联合调度模型,该模型中供热系统通过热电联产机组和交流电锅炉与交流电网耦合,通过直流电锅炉与直流电网耦合;最后,通过算例仿真验证了所提方法的有效性并说明了在电热联合调度中考虑交直流电源的必要性。