西安建筑科技大学学报(自然科学版)

为揭示中深层地埋管换热器周围岩土的热恢复特性,建立数值传热模型,基于有限差分法进行求解,并利用项目实测数据进行验证,在此基础上分析了中深层地埋管换热器周围岩土全年的温度场变化.主要得出以下结论:特定工况下,中深层地埋管换热器对其周围岩土的热影响范围有限,其热影响半径为9.3 m; 中深层地埋管换热器的取热区域主要集中在1 200～2 000 m的岩土; 岩土热恢复率随着恢复时间的增加而逐渐减小,以恢复两个月的热恢复率为基准,热恢复4个月、6个月、8个月热恢复率在前一基础上分别增加2.1%、0.9%和0.5%; 经过8个月的热恢复期,岩土能够基本恢复至初始温度,当r=0.3 m时埋管深度为1 200 m、1 600 m、1 800 m和2 000 m的岩土所对应的热恢复率分别达98.7%、97.9%、97.9%、98.2%.为中深层地源热泵系统的设计提供理论参考.

To reveal the heat recovery characteristics of the rock and soil around the deep borehole heat exchanger(DBHE), a numerical heat transfer model is established in this paper, which is solved based on the Finite Difference Method(FDM), and verified by the measured data of the project. On this basis, the annual temperature changes of the rock and soil around the DBHE are analyzed. The main conclusions are as follows: under specific working conditions, the heat influence range of the DBHE on the surrounding rock and soil is limited, and its heat-affected radius is 9.3 m; the heat extraction area of the DBHE is mainly concentrated in the rock and soil at a depth of 1 200～2 000 m; the thermal recovery rate of rock and soil gradually decreases with the increase of recovery time. Based on the thermal recovery rate of two months, the thermal recovery rates of four months, six months and eight months increase by 2.1%, 0.9% and 0.5% respectively, so the soil can basically recover to the initial temperature after 8 months of thermal recovery. When r=0.3 m, the corresponding thermal recovery rates of the buried pipe with depth of 1 200 m, 1 600 m, 1 800 m and 2 000 m are 98.7%, 97.9%, 97.9% and 98.2% respectively. This study can provide a theoretical reference for the design of DBHE.

引言
1 数值模型建立
2 数值模型求解及验证
3 结果与分析
4 结论

图1 中深层套管式地埋管换热器的取热原理<br/>Fig.1 Heat extraction principle of medium deep borehole heat exchanger

图1 中深层套管式地埋管换热器的取热原理
Fig.1 Heat extraction principle of medium deep borehole heat exchanger

图2 时间步长无关性验证<br/>Fig.2 Verification of time step independence

图2 时间步长无关性验证
Fig.2 Verification of time step independence

图3 节点数量无关性验证<br/>Fig.3 Verification of node number independence

图3 节点数量无关性验证
Fig.3 Verification of node number independence

表1 岩土层物理参数<br/>Tab.1 Physical parameters of rock and soil layer

表1 岩土层物理参数
Tab.1 Physical parameters of rock and soil layer

表2 模拟所需的物理参数<br/>Tab.2 Physical parameters required for simulation

表2 模拟所需的物理参数
Tab.2 Physical parameters required for simulation

图4 地源侧进出口温度实际值与模拟值比对[14]<br/>Fig.4 Comparison of actual and simulated temperature at the inlet and outlet of the ground source side

图4 地源侧进出口温度实际值与模拟值比对[14]
Fig.4 Comparison of actual and simulated temperature at the inlet and outlet of the ground source side

图5 中深层地埋管换热器周围岩土温度分布<br/>Fig.5 Temperature distribution of rock and soil around medium deep borehole heat exchanger

图5 中深层地埋管换热器周围岩土温度分布
Fig.5 Temperature distribution of rock and soil around medium deep borehole heat exchanger

图6 中深层地埋管换热器运行120 d后不同埋管深度径向岩土温度分布<br/>Fig.6 Radial geotechnical temperature distribution at different depths after 120 days operation of medium deep borehole heat exchanger

图6 中深层地埋管换热器运行120 d后不同埋管深度径向岩土温度分布
Fig.6 Radial geotechnical temperature distribution at different depths after 120 days operation of medium deep borehole heat exchanger

图7 模拟监测点位置[27]<br/>Fig.7 Location of monitoring points

图7 模拟监测点位置[27]
Fig.7 Location of monitoring points

图8 z=400 m处不同径向距离岩土温度<br/>Fig.8 Temperature distribution of monitoring points with different radial distances at z=400 m

图8 z=400 m处不同径向距离岩土温度
Fig.8 Temperature distribution of monitoring points with different radial distances at z=400 m

图9 r≤1 m范围内不同埋管深度处岩土温度<br/>Fig.9 Rock and soil temperature at different depths in the range of r≤1 m

图9 r≤1 m范围内不同埋管深度处岩土温度
Fig.9 Rock and soil temperature at different depths in the range of r≤1 m

图10 1 m<r≤6 m范围内不同埋管深度处岩土温度<br/>Fig.10 Rock and soil temperature at different depths in the range of 1 m<r≤6 m

图10 1 m<r≤6 m范围内不同埋管深度处岩土温度
Fig.10 Rock and soil temperature at different depths in the range of 1 m<r≤6 m

图11 中深层岩土在不同时间段的热恢复<br/>Fig.11 Thermal recovery of medium deep rock and soil at different time

图11 中深层岩土在不同时间段的热恢复
Fig.11 Thermal recovery of medium deep rock and soil at different time

图12 r=0.3 m处不同埋管深度的岩土热恢复率<br/>Fig.12 Thermal recovery rate of rock and soil with different depths at r=0.3 m

图12 r=0.3 m处不同埋管深度的岩土热恢复率
Fig.12 Thermal recovery rate of rock and soil with different depths at r=0.3 m

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备注

引言

1 数值模型建立

2 数值模型求解及验证

3 结果与分析

4 结论

期刊信息