| Most of mine geothermal energy is medium and low temperature geothermal resources,which cannot be widely developed and utilized due to the limitation of geothermal development technology and cost at present.However,mine geothermal energy,as a crucial part of geothermal resources,is rich in reserves and has great development potential in the future energy field.Therefore,the research on mine geothermal energy development has always been the focus of attention around the world.At the same time,with China’s continuous advancement to deep coal resources,there are both opportunities and challenges for the efficient development of deep mine geothermal energy.In view of this,an innovative geothermal exploiting method of functional backfilling for phase change heat storage in mine is proposed in this thesis,mainly focusing on basic theory and method of functional backfilling for phase change heat storage in deep mine.This thesis first develops the phase change heat storage functional backfilling materials suitable for deep mine geothermal energy development with the application of experimental investigation.The mechanical model which is used to describe phase change heat storage in the geothermal exploitation structure(GES)of mine functional backfilling is then developed.The heat replenishment mechanism of phase change heat storage function backfilling heat extraction in mines is investigated after theoretical analyses.Thereafter,the developed model is adopted to numerically study the regulation characteristics of different main control factors on the performance of phase change heat storage function backfilling heat extraction in deep mines.Then,the optimization analysis and design process of phase change heat storage function backfilling heat extraction system in deep mines is formed after field research and case study.The main innovative results achieved in the thesis are as follows:(1)A new method of exploiting geothermal energy in deep mines by phase change heat storage functional backfilling is proposed,the principle and technical key of geothermal exploiting technology by functional backfilling for phase change heat storage in deep mine(GE-TECH)are explained,the connotation of functional backfilling GES is revealed,the main control factors of phase change heat storage functional backfilling heat extraction performance and the principle of efficiency enhancement are derived,and the selection method of phase change temperature and phase change interval of functional backfilling materials is constructed.(2)The functional backfilling materials with suitable phase change parameters and excellent physical and chemical properties are developed,the influence of different material ratios on the physical and chemical properties of functional backfilling materials is studied,the mechanism of strength damage of functional backfilling materials by hydrophobic hole expansion of form-stable phase change material(F-PCM)is revealed,and the phase change heat transfer law of functional backfilling materials and rock cemented assemblies is analyzed.(3)The heat transfer experimental system of GES is developed,the heat transfer law and the phase change behavior of GES under the operation mode of "geothermal self-recovery" and "phase change rechargeable battery" are obtained,the evolutionary characteristics of the heat transfer channels of the GES under the influence of the master control factor are characterized,and the mechanism of phase change heat storage of the functionally backfilled GES is revealed.(4)The evolution law of heat conduction of deep mine phase change heat storage functional backfilling heat recovery is studied,and the heat recharge mechanism of the zoned and layered reservoir working face for mine geothermal exploitation(F-MGE)is revealed.Based on the principle of "phase change rechargeable battery" and "graded phase change functional heat charging",the regulation and control characteristics of phase change heat storage functional heat charging performance are derived,and the optimization analysis and design process of the deep mine phase change thermal charging system is developed.There are 117 pictures,37 tables and 205 references in this thesis. |
PDF Full Text Request