Characteristics of flow phase transition and heat transfer of N2O medium at the rock core scale of dry hot rock

IF 6.4 2区工程技术 Q1 THERMODYNAMICS

Case Studies in Thermal Engineering Pub Date : 2025-05-06 DOI:10.1016/j.csite.2025.106281

Yongsheng Liu , Jiansong Zhang , Jianxin Xia , Jianguo Lv

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引用次数: 0

Abstract

The phase characteristics of the heat exchange medium play a crucial role in the thermal performance of the heat reservoir in Enhanced Geothermal Systems. A numerical model was developed at the core scale for a two-dimensional rough single fracture, incorporating the phase-change behavior of N₂O. The thermal-hydraulic transport characteristics of liquid and supercritical N₂O within a single fracture in hot dry rock were investigated under varying inlet velocity and temperature conditions. The results reveal the following key findings: (1) When N₂O is in the supercritical state, vortex-like streamlines are more likely to form at the corners of the flow channel. Under high-velocity and low-temperature conditions, the temperature variation of N₂O at the fracture edges exhibits a more pronounced sawtooth pattern. (2) At an inlet velocity of 0.01 m/s, the phase state of N₂O varies at different locations within the fracture channel: liquid near the inlet and supercritical near the outlet. (3)Compared to the inlet temperature, the inlet velocity has a more pronounced effect on the heat extraction rate at the outlet. When the inlet velocity of N₂O is 0.01 m/s and the temperature is 40 °C, the maximum heat extraction rate reaches 830.89 W/m. These findings provide valuable insights into the thermal-hydraulic transport processes of heat exchange medium with phase-change characteristics in fractured reservoirs of hot dry rock.

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干热岩岩心尺度下N2O介质的流动、相变及传热特征

在增强型地热系统中，换热介质的相特性对储热系统的热性能起着至关重要的作用。在岩心尺度上建立了二维粗糙单断裂的数值模型，并考虑了N2O的相变行为。在不同入口速度和温度条件下，研究了干热岩石单条裂缝内液体和超临界N2O的热液输运特性。结果表明：①当N2O处于超临界状态时，流道转角更容易形成涡状流线；在高速低温条件下，断口边缘N2O的温度变化呈现更为明显的锯齿状特征。(2)在进口速度为0.01 m/s时，裂缝通道内不同位置的N2O相态不同，在进口附近为液态，在出口附近为超临界。(3)与进口温度相比，进口速度对出口热提取率的影响更为显著。当N2O入口速度为0.01 m/s，温度为40℃时，最大放热量达到830.89 W/m。这些发现为研究干热岩裂缝性储层相变热交换介质的热液输运过程提供了有价值的见解。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Case Studies in Thermal Engineering Chemical Engineering-Fluid Flow and Transfer Processes

CiteScore

8.60

自引率

11.80%

发文量

812

审稿时长

76 days

期刊介绍： Case Studies in Thermal Engineering provides a forum for the rapid publication of short, structured Case Studies in Thermal Engineering and related Short Communications. It provides an essential compendium of case studies for researchers and practitioners in the field of thermal engineering and others who are interested in aspects of thermal engineering cases that could affect other engineering processes. The journal not only publishes new and novel case studies, but also provides a forum for the publication of high quality descriptions of classic thermal engineering problems. The scope of the journal includes case studies of thermal engineering problems in components, devices and systems using existing experimental and numerical techniques in the areas of mechanical, aerospace, chemical, medical, thermal management for electronics, heat exchangers, regeneration, solar thermal energy, thermal storage, building energy conservation, and power generation. Case studies of thermal problems in other areas will also be considered.