Thermal Response Test by Improved Test Rig with Heating or Cooling Soil

An improved test rig providing both the heat and cold source was used to perform thermal response test （TRT）, and the line source model was used for data analysis. The principle of determining the temperature difference between the inlet and outlet of test well can keep the heating or cooling rate constant, along with a reduced size of test rig. Among the influencial factors of the line source model, the temperature difference was determined as the most important, which agreed with the test results. When the gravel was taken as the backfill material, the soil thermal conductivities of heating and cooling at the test place were 1.883 W/（m＆#183;K） and 1.754 W/（m＆#183;K）, respectively, and the deviation of TRT between heating and cooling soil was 6.8%. In the case of fine sand, the thermal conductivities of heating and cooling were 1.541 W/（m＆#183;K） and 1.486 W/（m＆#183;K）, respectively, and the corresponding deviation was 6%. It was also concluded that different velocities of water had less influence on TRT than the temperature difference.

Research on single hole heat transfer power of ground source heat pump system

In this paper,the single hole heat transfer power of the ground source heat pump system in Hengshui is compared with data gained from thermal response test.The results show that maximum monitoring data of heat transfer power per meter in summer is 97.1% of the test data,and the average value accounts for 81.8%.The per meter heat power data through on-site thermal response test can provide references for designing engineering project and optimizing ground source heat pump system as these data do not vary greatly from the actual monitoring data.

Numerical and experimental evaluation on methods for parameter identification of thermal response tests

Several parameter identification methods of thermal response test were evaluated through numerical and experimental study.A three-dimensional finite-volume numerical model was established under the assumption that the soil thermal conductivity had been known in the simulation of thermal response test.The thermal response curve was firstly obtained through numerical calculation.Then,the accuracy of the numerical model was verified with measured data obtained through a thermal response test.Based on the numerical and experimental thermal response curves,the thermal conductivity of the soil was calculated by different parameter identification methods.The calculated results were compared with the assumed value and then the accuracy of these methods was evaluated.Furthermore,the effects of test time,variable data quality,borehole radius,initial ground temperature,and heat injection rate were analyzed.The results show that the method based on cylinder-source model has a low precision and the identified thermal conductivity decreases with an increase in borehole radius.For parameter estimation,the measuring accuracy of the initial temperature of the deep ground soil has greater effect on identified thermal conductivity.

Heat transport of hybrid nanomaterial in an annulus with quadratic Boussinesq approximation

The convective heat transfer of hybrid nanoliquids within a concentric annulus has wide engineering applications such as chemical industries, solar collectors, gas turbines, heat exchangers, nuclear reactors, and electronic component cooling due to their high heat transport rate. Hence, in this study, the characteristics of the heat transport mechanism in an annulus filled with the Ag-MgO/H_2O hybrid nanoliquid under the influence of quadratic thermal radiation and quadratic convection are analyzed. The nonuniform heat source/sink and induced magnetic field mechanisms are used to govern the basic equations concerning the transport of the composite nanoliquid. The dependency of the Nusselt number on the effective parameters(thermal radiation, nonlinear convection,and temperature-dependent heat source/sink parameter) is examined through sensitivity analyses based on the response surface methodology(RSM) and the face-centered central composite design(CCD). The heat transport of the composite nanoliquid for the spacerelated heat source/sink is observed to be higher than that for the temperature-related heat source/sink. The mechanisms of quadratic convection and quadratic thermal radiation are favorable for the momentum of the nanoliquid. The heat transport rate is more sensitive towards quadratic thermal radiation.

Optimization of heat transfer in the thermal Marangoni convective flow of a hybrid nanomaterial with sensitivity analysis

The heat transfer rate of the thermal Marangoni convective flow of a hybrid nanomaterial is optimized by using the response surface methodology(RSM).The thermal phenomenon is modeled in the presence of a variable inclined magnetic field,thermal radiation,and an exponential heat source.Experimentally estimated values of the thermal conductivity and viscosity of the hybrid nanomaterial are utilized in the calculation.The governing intricate nonlinear problem is treated numerically,and a parametric analysis is carried out by using graphical visualizations.A finite difference-based numerical scheme is utilized in conjunction with the 4-stage Lobatto IIIa formula to solve the nonlinear governing problem.The interactive effects of the pertinent parameters on the heat transfer rate are presented by plotting the response surfaces and the contours obtained from the RSM.The mono and hybrid nanomaterial flow fields are compared.The hybrid nanomaterial possesses enhanced thermal fields for nanoparticle volume fractions less than 2%.The irregular heat source and the thermal radiation enhance the temperature profiles.The high level of the thermal radiation and the low levels of the exponential heat source and the angle of inclination(of the magnetic field)lead to the optimized heat transfer rate(Nux=7.46275).

TROPICAL ATMOSPHERIC NONLINEAR STEADY RESPONSE SOLUTION UNDER EFFECTS OF PAIRED HEAT SOURCES OF CONTRASTING NATURE

Based on steady semi-geostrophic model equations,analysis is carried out of the linear and nonlinear modification/response of the tropical atmosphere to the forcing of ideal paired heat sources of contrasting nature.Re- suits show that the linear part is dominant in the steady response but the nonlinear modification is quite noticable in the neighborhood of the heat source and between the paired sources,and the barotropic mode and second baroclinic mode play a different role in the modification,with the barotropic(second baroclinic)mode modification depending largely on the Rossby wave self-interaction(the magnitude due to the Kelvin-Rossby wave interaction)between the paired sources.

Thermal Response Test for Kelix GHE System

The performance of a BTES （borehole thermal energy storage） system is primarily governed by ground heat flux, soil thermal properties and groundwater conditions. However, the design of the heat exchanger used within the BTES system can also make a significant difference in the efficiency of the system. A thermal response test was carded out for a Kelix GHE （ground heat exchanger） system, the latest innovation in geothermal ground loop construction, on an Ecofarm in the town of Caledon East, Ontario, Canada. In addition, a verifying test was performed for a CEES （conventional earth energy system） located 6 m away from the Kelix GHE. The boreholes for these two different heat exchanger designs were drilled with the same diameter, to the same depth and were located in the same/identical geo-hydrological conditions. The response test provided the effective average of undisturbed ground temperature, geothermal properties including thermal conductivity, heat capacity and thermal resistance between the fluid and the borehole wall. The mathematical analysis method used for the response test is presented here. Results of the response test were verified, analyzed and are further discussed.

Thermal Efficiency Optimization of a Ground Source Heat Pump System by Assistant Preheating/Precooling: A Case Study on a Heating-Load Dominated Building

Operation strategies of Ground Source Heat Pump System(GSHPS) such as continuous or intermittent approaches have been extensively studied. In this work, a novel strategy was proposed to maximize the energy efficiency of GSHPS. In this approach, the buildings was first air-conditioned by the preheating/precooling mode and the rest thermal load was covered by the heat pump(HP) mode. The system performance can then be optimized by considering the combination of these two operating modes. A case study was made to examine the thermal performance of a GSHPS installed in Nuremberg, Germany. Thermal performance of the HP and the preheating/precooling operating modes was examined. The system was optimized by deploying the assistant preheating/precooling approach and over one-year period monitoring showed that the seasonal Coefficient of Performance(COP) of the GSHPS was 4.12 in winter and 5.01 in summer. These COP values are higher than that of the conventional GSHPS. Thus, this proposed strategy could be an efficient way to improve the thermal performance of GSHPS.

Prediction and parametric analysis of 3D borehole and total internal thermal resistance of single U-tube borehole heat exchanger for ground source heat pumps

The borehole and total internal thermal resistance are both significant parameters in evaluating the thermal performance of the ground source heat pump.This study aimed to obtain the accurate correlation of the 3D borehole and total internal thermal resistance(R_(b,3D)and R_(a,3D))and analyze the impacts of parameters on the R_(b,3D)and R_(a,3D).Firstly,eight parameters affecting the R_(b,3D)and R_(a,3D),including the borehole diameter,pipe diameter,pipe-pipe distance,borehole depth,soil thermal conductivity,grout thermal conductivity,pipe thermal conductivity,and fluid velocity inside the pipe,were considered and an L-54 design matrix was generated.Then,the 3D numerical model,coupling with the four-resistance model,was proposed to calculate R_(b,3D)and R_(a,3D)for each case.After that,the response surface methodology was employed to obtain and verify the correlation of R_(b,3D)and R_(a,3D),which were compared with the existing resistance calculation methods.Lastly,analysis of variance was carried out to reveal parameters that have statistically significant impacts on the R_(b,3D)and R_(a,3D).Results show that the rationality and accuracy of the correlation of R_(b,3D)and R_(a,3D)can be verified by the determination coefficient and P value of regression model,as well as the P value of lack-of-fit.The existing resistance calculation methods are more or less inaccurate and the discrepancies in some cases can be up to 86.74%and 111.35%for the borehole and total internal thermal resistance.The pipe and grout thermal conductivity,pipe and borehole diameter,and the pipe-pipe distance can be seen as the significant contributory factors to the variation of R_(b,3D)and R_(a,3D).

考虑氢储能和需求响应的综合能源系统双层优化配置

在双碳目标下,为改善综合能源系统功率不平衡,提高能源运营商收益,降低用户购能成本,首先,结合氢储能可作为源-荷-储的优点以及电制热的能源转换特性,设计了考虑氢储能的综合能源系统双层框架。其次,根据两种不同时间尺度,提出了一种考虑负荷侧需求响应和含电制热设备用户群的综合能源系统氢储能双层优化配置模型,上层模型结合氢储能特性进行长时间尺度优化配置;下层模型利用需求响应和电制热设备对用户群负荷进行优化,以求解短时间尺度含氢储能综合能源系统优化运行问题。再次,采用KKT条件和Big-M法将模型转为单层线性问题。最后,结果显示,通过配置氢储能以及采用电制热设备和需求响应,可提高运营商收入和新能源消纳,降低用户群成本,减少功率失衡风险。

考虑空气源热泵负荷聚合参与的需求响应

基于“电网-聚合商-负荷”三级架构,提出空气源热泵负荷聚合参与需求响应的控制策略。供暖运营商作为热泵负荷的聚合商,在保证用户热舒适度的基础上,利用建筑本身的蓄能能力,结合分时电价最小化供热成本,并对负荷可调节潜力进行评估。当电网调度部门下发调控指令后,考虑用户舒适度和电网调节需求,基于多目标遗传算法分配各负荷调节量,在满足调控目标的同时可改善调控带来的聚合功率振荡、反弹负荷大等问题。最后,仿真验证所提策略的有效性。

考虑富氧燃烧碳捕集技术和源荷双侧响应的综合能源系统优化调度

为降低燃气轮机的碳排放水平和提高灵活性,提出了计及富氧燃烧碳捕集技术和源荷双侧响应的综合能源系统低碳经济优化策略。首先,研究了富氧燃烧技术的运行原理及其能流特性,并构建空分制氧设备和碳捕集设备的耦合模型;其次,引入可调的热电比作为供给侧响应策略,需求侧对于电力、热能以及气负荷的特性进行综合权衡,借助能源价格的引导,并考虑其相互之间的可替代属性形成需求侧响应机制;最后,通过计及气负荷碳排放的阶梯式碳交易约束碳排放,以系统运行成本为目标优化各时段机组出力。设置多场景进行仿真分析,结果表明富氧燃烧碳捕集技术能够有效减少系统的碳排放量,源荷双侧响应能够灵活调节供给侧与需求侧的供能关系,并有效减少系统运行成本。

基于源荷储灵活资源协同的电热综合能源系统实验平台

当前能源转型背景下,发展综合能源系统是实现“碳达峰、碳中和”以及新型电力系统建设目标的重要途径。针对含多元化灵活资源的电热耦合系统,提出考虑“源-荷-储”协同的电热综合能源系统实验平台构建方案。设计考虑热电联产机组、电制热装置、蓄热罐以及电/热需求响应协同优化调度的实验案例,探讨实验平台在基础教学和拓展科研方面的用途。实验平台的建设为电气工程专业学生参与项目训练和创新实践类活动提供了重要的实践平台,有助于激发科研人员的探索性、创新性思维,促进理论研究和实验仿真的有机结合与良性循环,为综合能源系统领域的研究提供有力支撑。

基于实际工程的地埋管地源热泵回填材料导热性能差异分析

为研究实际工程应用中回填材料导热性能差异,以郑州市浅层地热能示范工程为研究对象,通过现场热响应试验、地温监测、数值模拟对中细砂、中细砂+水泥、中细砂+膨润土、原浆四种常见回填材料导热性能进行分析.研究结果表明:原浆的平均导热率最低为1.83 W/(m·℃),中细砂的平均导热率最大为2.17 W/(m·℃);同时中细砂排热和取热下单位深度换热量也为最大,分别为48.52 W/m和47.38 W/m.夏季制冷时中细砂+水泥材料温度仅升高0.0002℃,远低于中细砂材料温度升高;而冬季供暖时,四种材料的温度下降值相近,最小为4.2842℃.基于数值模拟结果,中细砂放热和吸热工况下热影响半径最小,为分别5.5 m和6 m;同时,岩土体温度增温速度由大到小为中细砂、原浆、中细砂+膨润土、中细砂+水泥.因此,中细砂导热性能最好,可作为研究区域地埋管地源热泵回填材料的首选.研究成果为场地条件相似地区地埋管地源热泵回填材料选择提供依据,并对推进郑州地区能源绿色低碳发展具有一定参考意义.

长沙市某区浅层地埋管岩土体热响应试验性能研究

长沙市某区为高新技术发展示范基地,能源冷热需求量大,该片区地质条件复杂,邻近少有地源热泵热响应测试数据,通过性能研究,揭露研究区地层以第四系覆盖层及元古界泥岩、砂岩、板岩为主,10~40 m存在上层少量上层滞水;通过线热源模型热响应试验,测试岩土体综合平均导热系数为1.78~1.95 W/(m·K),钻孔热阻值为0.18~0.23(m·K)/W,并与钻孔取芯和室内热物性测试进行对比,吻合度较好。考虑长沙地区气候特征,在不考虑大量钻孔换热过程中存在热干扰和长时间持续运行情况下,通过换热计算,夏季每延米换热量最大可达51~53 W/m,冬季每延米换热量最大取值为47~49 W/m。

陈四楼煤矿水余热利用节能装备技术的研究与应用

本文针对陈四楼煤矿原有传统供暖方式运行中存在的问题,分析了矿井水余热利用系统装备技术运行机理及选型设计,介绍了井筒矿井水余热利用系统装备技术工艺流程、运行特点及效益分析,并对实际应用中的矿井水余热利用效果进行了论证与研究,指出了煤矿生产资源节能装备技术高效利用模式在现代化矿井安全生产中的重要性。

EPC项目中地源热泵系统的设计优化与施工技术

浅层地热能是一种重要的新型能源,开发浅层地热能主要作用是为建筑物提供供暖制冷,目前利用浅层地热能作为冷、热源的地埋管地源热泵系统在工程中得到广泛应用。对芜湖某EPC公建项目地源热泵系统进行了研究,介绍了项目场地区域岩土热响应试验情况,根据相关规范要求进行了地埋管地源热泵系统的设计优化,阐述了地埋管地源热泵的施工技术。由岩土热响应试验得出芜湖地区适合做地源热泵系统,利用规范中热量平衡原理,优化了初步设计中地源热泵的数量和节点处理措施,缩短了施工工期并节省了工程造价,针对地源热泵施工过程中的技术难点提出应对措施,对工程实际具有参考意义。

内嵌需求响应的新型电力系统源网荷储协同优化技术

为了改善新型电力系统源网荷储协同优化技术中参数的复杂多样性与随机不确定性,降低电网运行成本,实现用户侧与需求侧用电平衡,研究内嵌需求响应的新型电力系统源网荷储协同优化技术。基于新型电力系统源网荷储结构,构建包含负荷资源和储能资源的用户侧需求响应模型,便于考虑用户需求响应调整用户侧用电方式,产生可中断负荷或转移负荷。需求侧响应以用户补贴费用最低、系统损耗最小为目标函数,结合负荷侧、储能设备、可控分布式电源、电网功率平衡约束条件,构建源网荷储协同优化模型,并采用遗传算法通过交叉、变异运算求解获取需求响应补贴费用最低、系统损耗最小的协同优化结果。实验结果表明:在不同情景下,经过本文方法协同优化后,可降低热电出力,增加系统风电消纳空间,将电价高时期负荷转移至低时期;实现用电负荷平衡,在负荷低时有效提升风电消纳空间,提高供电效率,减少成本损耗与需求响应成本。

基于叠加理论的柱热源模型岩土体热响应试验测试研究

岩土体热物性参数是计算浅层地热能资源量和进行地热能利用规划设计需要的重要参数,为获取岩土体热物性参数,本文基于叠加理论的柱热源模型,分析了换热孔内外相应的传热数学模型及数据拟合计算方法,以江苏省宿迁沭阳城区HRK1号孔为例,采用了恒定热流法试验测试,取得了现场热响应试验测试数据,采用基于叠加理论的柱热源数学模型对数据进行了拟合分析,分析结果表明,当埋管深度98.7 m,初始温度19.80℃,实际平均加热功率为3829 W,平均流量为1.30m^(3)/h(流速为0.68 m/s)时,岩土综合导热系数为2.32 W/(m·K),体积比热容为1.42×10^(3)J/(kg·K),换热孔内总热阻为0.125(m·K)/W。结果表明,基于叠加理论建立的柱热源模型处理现场热响应试验测试数据是可行的,可用于现场热物性测试数据的处理分析。

空气源热泵干燥技术在粮食干燥中应用与展望

目前粮食干燥方式受限于环境和人工条件,极大地限制了粮食加工行业的发展,因此,寻求高效的干燥技术与装备成为粮食加工行业发展的重要目标。梳理了国内外空气源热泵干燥技术与装备的研发应用现状,以系统控制和工艺参数为研究对象,研究空气源热泵干燥技术的装备结构与工作原理,分析了干燥装备存在的干燥不均匀、能耗大、效率低等问题产生的原因,并探讨了相应改善方法;针对多重组合干燥技术,分析了微波、太阳能与远红外3类与空气源热泵干燥技术联合方式下的干燥优势,探讨了联合干燥技术相较于单一干燥技术在装备和工艺中存在的优势和不足。结合干燥行业发展问题,从联合干燥技术研究方向、联合干燥工艺改进、干燥信息平台搭建、干燥设备研发升级4个方面对联合干燥在粮食干燥领域进行了展望,以期为干燥领域发展和装备创新提供参考。