The overall heat transfer coefficient(OHTC)of rock fractures is a fundamental parameter for characterizing the heat transfer behavior of rock fractures in hot dry rock(HDR)geothermal mining.Although a number of practi...The overall heat transfer coefficient(OHTC)of rock fractures is a fundamental parameter for characterizing the heat transfer behavior of rock fractures in hot dry rock(HDR)geothermal mining.Although a number of practical formulae for heat transfer coefficients have been developed in the literature,there is still no widely accepted analytical solution.This paper constructs highly accurate analytical solutions for the temperatures of the inner fracture wall and the fluid.Then they are employed to develop new definition-based formulae(formula A and its simplification formula B)of the OHTC,which are well validated by the experimental and numerical simulation results.An empirical correlation formula of heat transfer coefficient is proposed based on the definition-based formulae which can be directly used in the numerical simulations of heat transfer in rock fractures.A site-scale application example of numerical simulation also demonstrates the effectiveness of the empirical correlation formula.展开更多
Testing of large-sized specimens is becoming increasingly important in deep underground rock mechanics and engineering.In traditional mechanical loading,stresses on large-sized specimens are achieved by large host fra...Testing of large-sized specimens is becoming increasingly important in deep underground rock mechanics and engineering.In traditional mechanical loading,stresses on large-sized specimens are achieved by large host frames and hydraulic pumps,which could lead to great investment.Low-cost testing machines clearly always have great appeal.In this study,a new approach is proposed using thermal expansion stress to load rock specimens,which may be particularly suitable for tests of deep hot dry rock with high temperatures.This is a different technical route from traditional mechanical loading through hydraulic pressure.For the rock mechanics test system of hot dry rock that already has an investment in heating systems,this technology may reduce the cost of the loading subsystem by fully utilizing the temperature changes.This paper presents the basic principle and a typical design of this technical solution.Preliminary feasibility analysis is then conducted based on numerical simulations.Although some technical details still need to be resolved,the feasibility of this loading approach has been preliminarily confirmed.展开更多
Carbon capture,utilization,and storage(CCUS)is widely recognized as a technological system capable of achieving large-scale carbon dioxide emission reductions.However,its high costs and potential risks have limited it...Carbon capture,utilization,and storage(CCUS)is widely recognized as a technological system capable of achieving large-scale carbon dioxide emission reductions.However,its high costs and potential risks have limited its large-scale implementation.This study focuses on enhancing the economic viability of traditional CCUS by proposing a novel technological concept and system that integrates CCUS with water extraction,geothermal energy harvesting,hydrogen production,and energy storage.The system comprises three interconnected modules:(1)upstream CO_(2)-enhanced water recovery(CO_(2)-EWR),(2)midstream green hydrogen synthesis,and(3)downstream energy utilization.Through detailed explanations of the fundamental concept and related technological systems,its feasibility is demonstrated.Preliminary estimates indicate that under current conditions,the system lacks economic advantages.However,significant reductions in hydrogen production costs could enable the system to yield a profit of nearly 1000 Chinese Yuan(approximately 145 US dollars)per ton of CO_(2)in the future.Following an in-depth investigation,priority implementation in China's Tarim Basin and Ordos Basin is recommended.This technological system could significantly extend the industrial chain of traditional CCUS projects,promising additional social and ecnomic benefits.Furthermore,the involved gas-water displacement technology can help manage formation pressure and reduce leakage risks in large-scale carbon storage projects.展开更多
基金support of this work by the National Natural Science Foundation of China (Grant Nos.41972316 and 41672252).
文摘The overall heat transfer coefficient(OHTC)of rock fractures is a fundamental parameter for characterizing the heat transfer behavior of rock fractures in hot dry rock(HDR)geothermal mining.Although a number of practical formulae for heat transfer coefficients have been developed in the literature,there is still no widely accepted analytical solution.This paper constructs highly accurate analytical solutions for the temperatures of the inner fracture wall and the fluid.Then they are employed to develop new definition-based formulae(formula A and its simplification formula B)of the OHTC,which are well validated by the experimental and numerical simulation results.An empirical correlation formula of heat transfer coefficient is proposed based on the definition-based formulae which can be directly used in the numerical simulations of heat transfer in rock fractures.A site-scale application example of numerical simulation also demonstrates the effectiveness of the empirical correlation formula.
基金National Natural Science Foundation of ChinaGrant/Award Number:41972316+3 种基金Sichuan Science&Technology FoundationGrant/Award Number:2022YFSY0007Joint Funds of the National Natural Science Foundation of ChinaGrant/Award Number:U2344226。
文摘Testing of large-sized specimens is becoming increasingly important in deep underground rock mechanics and engineering.In traditional mechanical loading,stresses on large-sized specimens are achieved by large host frames and hydraulic pumps,which could lead to great investment.Low-cost testing machines clearly always have great appeal.In this study,a new approach is proposed using thermal expansion stress to load rock specimens,which may be particularly suitable for tests of deep hot dry rock with high temperatures.This is a different technical route from traditional mechanical loading through hydraulic pressure.For the rock mechanics test system of hot dry rock that already has an investment in heating systems,this technology may reduce the cost of the loading subsystem by fully utilizing the temperature changes.This paper presents the basic principle and a typical design of this technical solution.Preliminary feasibility analysis is then conducted based on numerical simulations.Although some technical details still need to be resolved,the feasibility of this loading approach has been preliminarily confirmed.
基金Joint Funds of the National Natural Science Foundation of China,Grant/Award Number:U2344226。
文摘Carbon capture,utilization,and storage(CCUS)is widely recognized as a technological system capable of achieving large-scale carbon dioxide emission reductions.However,its high costs and potential risks have limited its large-scale implementation.This study focuses on enhancing the economic viability of traditional CCUS by proposing a novel technological concept and system that integrates CCUS with water extraction,geothermal energy harvesting,hydrogen production,and energy storage.The system comprises three interconnected modules:(1)upstream CO_(2)-enhanced water recovery(CO_(2)-EWR),(2)midstream green hydrogen synthesis,and(3)downstream energy utilization.Through detailed explanations of the fundamental concept and related technological systems,its feasibility is demonstrated.Preliminary estimates indicate that under current conditions,the system lacks economic advantages.However,significant reductions in hydrogen production costs could enable the system to yield a profit of nearly 1000 Chinese Yuan(approximately 145 US dollars)per ton of CO_(2)in the future.Following an in-depth investigation,priority implementation in China's Tarim Basin and Ordos Basin is recommended.This technological system could significantly extend the industrial chain of traditional CCUS projects,promising additional social and ecnomic benefits.Furthermore,the involved gas-water displacement technology can help manage formation pressure and reduce leakage risks in large-scale carbon storage projects.
