Thermo-Economic Performance of Geothermal Driven High-Temperature Flash Tank Vapor Injection Heat Pump System:A Comparison Study

Process heating constitutes a significant share of final energy consumption in the industrial sector around the world.In this paper,a high-temperature heat pump(HTHP)using flash tank vapor injection technology(FTVI)is proposed to develop low-temperature geothermal source for industrial process heating with temperature above 100°C.With heat sink output temperatures between 120°C and 150°C,the thermo-economic performance of the FTVI HTHP system using R1234ze(Z)as refrigerant is analyzed and also compared to the single-stage vapor compression(SSVC)system by employing the developed mathematical model.The coefficient of performance(COP),exergy efficiency(ηexe),net present value(NPV)and payback period(PBP)are used as performance indicators.The results show that under the typical working conditions,the COP andηexe of FTVI HTHP system are 3.00 and 59.66%,respectively,and the corresponding NPV and PBP reach 8.13×106 CNY and 4.13 years,respectively.Under the high-temperature heating conditions,the thermo-economic performance of the FTVI HTHP system is significantly better than that of the SSVC system,and the larger the temperature lift,the greater the thermo-economic advantage of the FTVI HTHP system.Additionally,the FTVI HTHP system is more capable than the SSVC system in absorbing the financial risks associated with changes of electricity price and natural gas price.

Geothermal anomalies in the Xianshuihe area: Implications for tunnel construction along the Sichuan-Tibet Railway, China

This study presents a comprehensively analysis of geothermal characteristics in the Xianshuihe geothermal area along the Sichuan-Tibet Railway,using temperature logging,temperature monitoring and thermal conductivity measurement,and regional geothermal geological survey data.The research focuses on the geothermal background,geothermal field,and their potential impact on the surrounding tunnels.The investigation reveals that the average heat flow value in the study area is approximately 73.0 mW/m^(2),significantly higher than the average terrestrial heat flow in China's Mainland(62.5 mW/m^(2)).This high terrestrial heat flow signifies a distinct thermal background in the area.In addition,geothermal anomalies in the area are found to be closely associated with the distribution of hot springs along NW faults,indicating a strong control by the Xianshuihe fault zone.The study concludes that the region's favorable conditions for geothermal resources are attributed to the combination of high terrestrial heatflow background and water-conducting faults.However,these conditions also pose a potential threat of heat damage to the tunnels along the Sichuan-Tibet Railway.To evaluate the risk,the research takes into account the terrestrial heat flow,thermal conductivity of the tunnel surrounding rocks,characteristics of the regional constant temperature layer,as well as the distribution of hot springs and faults.The analysis specifically focuses on the thermal damage risk of Kangding 1# tunnel and 2# tunnel passing through the study area.Based on the findings,it is determined that Kangding 1# tunnel and 2# tunnel have relatively low risk of heat damage,as they have avoided most of the high temperature anomaly areas.However,several sections of the tunnels do traverse zones with low to medium temperatures,where surface rock temperatures can reach up to 45℃.Therefore,these regions should not be neglected during the construction and operation of the tunnel project,and mitigation measures may be necessary to address the potential heat-related challenges in the area.

Analyses of non-aqueous reactive polymer insulation layer in high geothermal tunnel

The scenario of geothermal tunnel is commonly observed around the world,and increases with the new constructions in the long and deep tunnels,for example in China.Tunnel insulation is generally divided into active and passive insulation.In passive insulation,it is an effective way to set low thermal con-ductivity materials as the thermal insulation layer as the choice of insulation material mainly depends on the thermal conductivity.Polymer is a kind of material with good geothermal performance,but there are relatively few studies.In this context,the transient plane source(TPS)method was used to measure the thermal conductivity of the developed polymer.Then,the temperature field of the high geothermal tunnel insulated by the non-aqueous reactive polymer layer was simulated.With the parametric analysis results,the suggestions for the tunnel layers were proposed accordingly.It revealed that the thermal conductivity of polymer first increases and then decreases with temperature.There are two rising sec-tions(?40e10?C and 20e90?C),one flat section(10e20?C)and one descending section(>90?C).It is observed the thermal conductivity of polymer increases with increase of the density of insulation layer and the density,and the thermal conductivity decreases when exposed to high temperatures.The temperature of the surrounding rocks increases with increase of the thermal conductivity and the thickness of polymer.Finally,a more economical thickness(5 cm)was proposed.Based on the parametric study,a thermal insulation layer with thermal conductivity less than 0.045 W/(m K),thickness of 5 cm and a density less than 0.12 g/cm 3 is suggested for practice.

Geothermal energy exploitation from depleted high-temperature gas reservoirs by recycling CO_(2): The superiority and existing problems

CO_(2) can be used as an alternative injectant to exploit geothermal energy from depleted high-temperature gas reservoirs due to its high mobility and unique thermal properties.However,there has been a lack of systematic analysis on the heat mining mechanism and performance of CO_(2),as well as the problems that may occur during geothermal energy exploitation at specific gas reservoir conditions.In this paper,a base numerical simulation model of a typical depleted high-temperature gas reservoir was established to simulate the geothermal energy exploitation processes via recycling CO_(2) and water,with a view to investigate whether and/or at which conditions CO_(2) is more suitable than water for geothermal energy exploitation.The problems that may occur during the CO_(2)-based geothermal energy exploitation were also analyzed along with proposed feasible solutions.The results indicate that,for a depleted low-permeability gas reservoir with dimensions of 1000 m×500 m×50 m and temperature of 150℃ using a single injection-production well group for 40 years of operation,the heat mining rate of CO_(2) can be up to 3.8 MW at a circulation flow rate of 18 kg s^(-1)due to its high mobility along with the flow path in the gas reservoir,while the heat mining rate of water is only about 2 MW due to limitations on the injectivity and mobility.The reservoir physical property and injection-production scheme have some effects on the heat mining rate,but CO_(2)always has better performance than water at most reservoir and operation conditions,even under a high water saturation.The main problems for CO_(2) circulation are wellbore corrosion and salt precipitation that can occur when the reservoir has high water saturation and high salinity,in which serious salt precipitation can reduce formation permeability and result in a decline of CO_(2) heat mining rate (e.g.up to 24%reduction).It is proposed to apply a low-salinity water slug before CO_(2)injection to reduce the damage caused by salt precipitation.For high-permeability gas reservoirs with high water saturation and high salinity,the superiority of CO_(2) as a heat transmission fluid becomes obscure and water injection is recommended.

TK7 High-Temperature Tunnel Kiln Computer Control System of SRIC Thailand

Based on the TK7 high-temperature tunnel kiln computer control system, this article describes the control line system, the automatic loop control which has been realized in firing zone temperature, inner and bottom pressure and flow, and logic control of kiln doors and pusher, etc. In addition, this system integrates the product information management system of magnesite brick and efficiently ensures the important process parameters. During three months performance of the control system, all parameters and energy consumption have turned out a good result.

Mapping and resource evaluation of deep high-temperature geothermal resources in the Jiyang Depression,China

In China,geothermal resource utilization has mainly focused on resources at shallow and medium depths.Yet,the exploration of deep,high-temperature geothermal resources holds significant importance for achieving the“dual carbon”goals and the transition of energy structure.The Jiyang Depression in the Bohai Bay Basin has vast potential for deep,high-temperature geothermal resources.By analyzing data from 2187 wells with temperature logs and 270 locations for temperature measurement in deep strata,we mapped the geothermal field of shallow to medium-deep layers in the Jiyang Depression using ArcGIS and predicted the temperatures of deep layers with a burial depth of 4000 m.Through stochastic modeling and numerical simulation,a reservoir attribute parameter database for favorable deep,high-temperature geothermal areas was developed,systematically characterizing the spatial distribution of geothermal resources within a play fairway of 139.5 km2 and estimating the exploitable deep geothermal resource potential by using the heat storage method and Monte Carlo data analysis.The study reveals that the Fan 54 well block in the Boxing-Jijia region is of prime significance to develop deep,high-temperature geothermal resources in the Jiyang Depression.Strata from the Cenozoic to the Upper Paleozoic are identified as effective cap layers for these deep geothermal resources.The Lower Paleozoic capable of effectively storing thermal energy and possessing an exploitable resource volume up to 127 million tons of standard coal,is identified as a target system for the development of deep high-temperature geothermal resources,providing significant insights for the efficient development of geothermal resources in the Jiyang Depression.

Construction technology for deep tunnels crossing superhigh-temperature fault zones with high water surges

The harsh environment in tunnels with high geothermal temperatures and humidity can adversely impact machinery,personnel,and construction.The main causes of specific problems are the unknown mechanisms of local geothermal formation,inappropriate temperature control measures,and insufficient systematic safeguards.In this study,three work sections relating to a high geothermal tunnel are:the tunnel face,middle-of-tunnel section,and outside-oftunnel section.A cooling strategy is proposed to offer technical support in achieving comprehensive cooling,overall as well as for each of the sections.First,a comprehensive geological survey explores the mechanism and exact location of the heat source.Secondly,grouting and centralized drainage measures are used to control the heat release of hot water.Enhanced ventilation,ice chillers and other applicable measures are used to control the ambient temperature.Finally,a monitoring and early warning system is established to prevent accidents.This cooling strategy has been applied in the field with good results.

考虑喷射混凝土耐热性能的高地温隧道支护结构研究

为获得适用于高地温隧道的支护特征曲线,依托某隧道,模拟高地温环境,通过材料组配设计、室内试验等手段,对喷射混凝土耐热性能进行研究。结果表明:配合比为0.45,使用无碱速凝剂、单掺20%矿粉的喷射混凝土,在35℃养护下性能较好。与标准养护条件相比,28 d抗压强度提高了10%,劈拉强度提高了14%。对岩石表面湿润后的干热环境下,其与岩石的黏结强度较高,较标准条件下,强度提高了44%。单掺矿粉替代水泥可降低水化热,在高温环境中能略微提升混凝土的各项性能。喷射混凝土具有明显的时变特性,考虑其时变特性可有助于合理支护时机的选取。研究成果有助于解决高地温隧道的热害问题,亦可为工程中相似热害环境支护问题提供参考。

地热区隧道施工热害分级防护方法研究

当隧道掘进进入地热区,隧道施工区间的高热环境不但危害隧道工程质量,而且影响工程进度和施工安全。把握地热区隧道施工的热环境特点,采取有效、经济的热害防护措施,是地热区隧道施工技术的关键。目前,热害防护措施的选择缺乏科学依据,容易因“欠防护”而造成热害防护效果不到位,或因“过防护”而造成资源浪费。本文根据地热区施工隧道热源及施工热环境特点,提出了一种基于热害水平评价的热害分级防护方法。该方法考虑影响施工热害的关键因素,运用模糊评价法对隧道热害水平进行评价,根据热害评价结果采取与之匹配等级的热害防护措施进行防护。该方法在满足热害防护效果要求的同时,可降低热害防护成本、减少能耗。

基于工人生理参数的隧道施工湿热环境分级研究

为解决高地温隧道高温高湿施工环境对施工人员的健康危害问题,降低施工过程中的风险,对我国某高地温隧道施工现场空气干球温度、空气相对湿度、湿球黑球温度(简称WBGT指数)及进行中等强度劳动的20名施工工人的上臂皮肤温度和心率进行多组实时连续监测。基于实测数据及数学规划法,将该高地温隧道湿热环境划分为低风险、较低风险、中风险、较高风险、高风险5个等级,确定各等级下的湿热环境参数阈值。结果表明:1)该高地温隧道施工环境中空气干球温度、空气相对湿度、WBGT指数的低风险阈值分别为26℃、30%、20℃,中风险阈值分别为37℃、64%、32℃,高风险阈值分别为43℃、81%、40℃。2)进一步计算得到不适指数、热指数和相对应变指数的中风险阈值分别为25.42、26.31、0.28℃;高风险阈值分别为28.59、35.30、0.38℃。

基于热源量化的高温隧道动态综合降温措施研究

为了实现高温隧道降温措施动态化、精准化设计,基于理论分析和现场实测,依托某高岩(水)温铁路隧道,对隧道内的高温热水、围岩、施工机械、水泥水化、爆破、施工人员散热量及不同降温措施冷量进行了理论分析研究,并根据风流温度和能量平衡原理得到了不同工况下高温隧道的冷量缺口。结果表明:高温围岩和超高温热水是隧道内的主要热源,其中高温热水散热量比例达到总散热量的50%以上;洞内放置冰块产生的冷量较小,通风带来的冷量较大,但其冷量会随着通风距离的增加而减小,其衰减规律可用二次曲线近似表示;200 m^(3)/h高温热水理论计算得到的换热风流温度31.8℃与现场实测温度31.0℃基本吻合。本文采用的分析方法获得的冷量缺口可作为选择机械制冷和降温措施动态化设计的理论依据,也可为类似的高温隧道降温设计提供参考。

基于混凝土强度的高地热隧道隔热层厚度研究

随着“长大深”隧道的发展,越来越多高地热隧道得以建设。高地热作为典型的不良地质之一,不仅会给隧道施工带来不便,还会严重危害隧道结构的安全。为减小高温对高地热隧道的不利影响,首先,调研相关文献,明确了温度与衬砌混凝土强度之间的关系;然后,以西部高原地区某高地热隧道为依托,使用Comsol数值模拟软件建立该隧道的温度场计算模型。通过数值计算得到各工况下衬砌混凝土的平均养护温度,并将其与强度相对应,并从保护衬砌混凝土强度的角度研究了各工况下不同厚度隔热层的作用。研究得到以下结论:(1)根据他人试验结果总结发现,隧道施工时应保证混凝土养护温度低于40℃,否则会严重降低衬砌混凝土的强度;(2)提出高地热环境隧道施工时隔热层的选取方案,55℃以下的地温段,无需使用隔热层;55~65℃地段,推荐使用3 cm隔热层;65~75℃地温段,使用5 cm隔热层;75~85℃地温段,若能保证洞内气温维持在28℃以内,使用5 cm隔热层,否则使用10 cm隔热层;高于85℃的地段,推荐使用10 cm隔热层。

高地温TBM铁路隧道施工应对措施研究

为了改善高地温TBM铁路隧道的高温热害问题,依托某特长铁路隧道工程,通过大量资料调研并综合国内外已有高地温TBM隧道施工降温技术措施,同时结合该隧道高地温具体情况,提出了一套系统的TBM高地温隧道热害防治的综合降温技术方案。研究表明,综合国内外地下洞室施工温度控制标准,建议高地温TBM铁路隧道洞内施工温度控制在28℃以下;采用加强通风、洒水降温、冰块降温、人工制冷等降温技术并结合隧道支护体系防热措施可防治TBM隧道高岩热;采用红外探水超前预测、化学注浆、热水归管引排等“以防堵为主,引水排水相结合”的原则可防治TBM隧道高温热水。根据该隧道热害具体情况采用热害分级防控总原则,将隧道热害分为4个等级并采取针对性治理措施,减少热害防控对施工进度的影响,节约经济。研究成果可为高地温TBM铁路隧道及其他类似工程提供参考。

山区带状交通工程物探技术研究及应用

山区带状交通工程物探通常面临崎岖地形、高山峡谷、飞水暗河、植被茂盛、陡倾地层等复杂地理环境和地质构造影响。当前,针对山区的物探方法手段单一、技术思路不开阔、数据信息严重不足,存在勘察盲区,尚未形成技术体系,难以有效提导钻探,存在重大地质风险,严重影响后续勘察设计和工程造价。以崎岖山岭DGT深埋长隧道紧邻断裂带和高山峡谷BFSH深埋特长隧道穿越地热发育区勘察项目为依托,运用大数据思维,对近几年涌现出来的航空物探、广域频电磁法、地震微动以及井中物探等新技术进行系统研究,试验攻关综合物探技术在山区勘察的有效性,揭示复杂地形地质条件下工程物探面临的问题并提出针对性措施,综合利用遥感、地质、钻探、试验等勘察技术,建立了“空天地”+“工可-初勘-详勘”多场源一体化勘察模式,形成了数据量大、属性要素全面、动态的勘察大数据,准确识别了断裂带、地热性质、围岩质量和岩土分界面,为优化线路和钻探选位打下良好的基础。通过案例研究,认为运用大数据思维可以提高山区工程勘察设计水平,采用综合技术可以提高地质参数的准确性。

考虑环境湿度条件下高地温隧道喷雾降温研究

为了解决高地温隧道施工环境的热害难题,探究喷雾降温辅助手段降温效果并确定其设计参数,以我国西南地区某隧道工程为依托,采用现场实测和数值模拟方法,就不同雾滴温度、喷头位置和流量对高地温隧道中不同截面位置温度场湿度场分布影响问题进行了深入分析。研究结果表明:喷雾系统弱化了围岩加热新鲜风的过程,使各截面气温显著降低2~3℃;处于喷头后方的隧道截面降温幅度更大,该范围为30 m左右,超出此范围,改变喷头位置不会对其后方隧道气温和湿度产生明显影响;围岩温度35℃、新鲜风25℃的条件下,设置喷雾流量和雾滴温度为0.005 kg/s和20℃可以将掌子面附近100 m范围内气温和相对湿度控制在27℃和47%左右;增加喷头流量是降低隧道环境气温的有效方式,而改变雾滴温度的影响作用较小。

基于高地温隧道热流耦合温度场的数值模拟研究

以实际工程为依托,结合能量传输方程,考虑流场和温度场的相互影响,建立三维隧道热流耦合模型,应用Fluent计算软件,在实际监测数据验证的基础上,对隧道施工过程中的通风降温问题进行分析研究。结果表明:通风温度、通风风速和通风管与工作面距离均对通风降温的效果造成一定影响,其中通风温度的影响最大;当通风温度越低、通风风速越大、通风管距离工作面越近时,隧洞内的空气温度环境越好,降温效果越明显;在选定的工况中,最高降温为24.4℃,最低降温为7.1℃;通风温度为5℃和10℃的工况中,主要工作活动范围区域内(距离工作面100 m范围内)的平均空气温度值能够满足小于28℃的要求。

渝昆高速铁路彝良隧道高地温工程地质特性分析

拟建渝昆高速铁路通过云贵高原斜坡过渡带,地质条件复杂,深埋长大隧道多,其中彝良隧道存在高地温工程地质问题。本文根据彝良隧道水文地质调绘及深孔测试等成果,对该隧道高地温可能存在的热源进行了分析,根据隧道地温测试情况,对隧道高地温进行了危害性分级。研究结果表明:(1)拟建彝良隧道区地表无热泉出露,深孔最高实测井温为39.31℃;(2)彝良隧道地热热储层为志留系中统大路寨组(S_(2)d),地热增温类型为地温梯度增温,地下热能的赋存形式为热水型;(3)彝良隧道在接收大气降水和地表径流补给后,地下水自北东向南西,沿大路寨组(S_(2)d)地层中岩溶裂隙或局部的管道顺龙池背斜轴往倾伏端深部径流,受地温梯度增温作用,形成高温热水,赋存于热储层大路寨组(S_(2)d)中;(4)彝良隧道D4K 320+900~D4K321+300、D4K326+190~D4K327+500段属低高温带,热害轻微;D4K321+300~D4K326+190段属中高温带,热害中等。研究成果可为隧道设计和施工提供参考依据。

科研反哺教学在建筑材料实验课程中的实践

建筑材料是一门实践性较强的课程,实验教学是本课程的重要组成部分,也是提升学生实践创新能力的重要环节。在科研反哺教学的导向下,以高地温隧道喷射混凝土的变形性能为例,探索科研成果转化为建筑材料课程创新性实验教学资源的实践方法。通过“学生参与-学生主导-学科交叉”的方式,可以使学生快速融入创新性实验,有助于激发学生的学习兴趣和科研热情,提升学生的自主创新和融合贯通能力,进而培养出满足重大战略工程需求的创新型与复合型高素质人才。

能源隧道的研究与应用现状

能源隧道是一种新型的能源利用技术,具有高效、环保和可持续等优点,其在能源领域的研究与应用受到的关注越来越多。基于国内外能源隧道的研究与应用现状,分析了能源隧道中热交换管传热性能的影响因素,总结了热交换管的选择和布置方式,并对能源隧道在温度变化时引起的衬砌结构响应和地面沉降进行了分析。研究结果表明:能源隧道的研究与应用应充分考虑传热性能的影响因素对热交换效率的影响;衬砌温度越大,产生的应力应变就越大;地下市政管线和地下综合管廊产生的废热再利用是能源隧道一个重要的研究方向,且应尽快制定能源隧道设计与施工的相关技术标准。

高地热隧道衬砌混凝土的配制参数研究

针对西部地区隧道施工面临的高地热问题,研究了水泥种类对20、60、80℃的衬砌混凝土早期水化温升和抗压强度的影响,并模拟分析了隧道地热环境下不同含气量衬砌混凝土的塑性变形及抗压强度增长规律、外掺石粉制备的低含气量衬砌混凝土的工作性和力学性能以及不同种类保水剂对衬砌混凝土早期失水率的影响,提出了高地热隧道衬砌混凝土的最佳配制参数。结果表明:在高地热环境下低热水泥衬砌混凝土的水化温升较普通水泥衬砌混凝土降低了4℃,90 d抗压强度提高了11.5%~16.5%;衬砌混凝土的含气量越高,高温对其后期强度的降低幅度越显著;复掺石粉可有效改善低含气量衬砌混凝土的工作性,石粉掺量宜为6%~15%;保水剂聚丙烯酰胺对抑制衬砌混凝土早期失水的作用优于纤维素醚,聚丙烯酰胺掺量宜为0.05%~0.10%。