摘要
同轴套管式地热能开采技术是用于中深层地热能开采的有效方式。为了增强同轴套管式换热器的换热效率,提出了一种带螺旋翅片的新型同轴套管式换热器。基于有限体积法,对比分析新型与普通型同轴套管式换热器的换热性能,得到螺旋翅片结构对换热性能的影响,揭示其强化传热机理。结果表明:通过增加螺旋翅片的翅高或减小螺旋翅片的螺距,可有效增强同轴套管式换热器内流体流动的湍流动能,达到提高换热性能的目的;与普通光滑管换热器相比,翅高为19 mm,螺距为300 mm的新型换热器在雷诺数为27000时,努赛尔数提高了35.5%,摩擦系数提高了91%,热性能系数达到最高1.093;增加翅片和减小螺距都可以增加采出温度和采热功率,翅高为19 mm,螺距为300 mm换热器较光滑管换热器采热温度提高了5.4 K,采热功率提高了32.4%。为高效同轴套管式换热器设计提供了理论依据。
Coaxial borehole geothermal energy mining technology is an effective method for medium and deep geothermal energy mining. In order to enhance the heat exchange efficiency of the coaxial borehole heat exchanger, a new type of coaxial borehole heat exchanger with spiral fins is proposed, based on the fintric volume method, the heat transfer performance of the new and ordinary coaxial borehole heat exchangers is compared and analyzed, and the influence of the spiral fin structure on the heat transfer performance is obtained, and the enhanced heat transfer mechanism is revealed. The results show that by increasing the fin height of the spiral fin or reducing the pitch of the spiral fin, the turbulent flow energy of the fluid flow in the coaxial borehole heat exchanger can be effectively enhanced, and the purpose of improving the heat transfer performance can be achieved. Compared with ordinary smooth tube heat exchangers, the new heat exchanger with a fin height of 19 mm and a pitch of 300 mm increased the Nusselt number by 35.5%, the friction coefficient by 91%, and the PEC reached a maximum of 1.093 when the Renault number was 27,000. Increasing the fins and decreasing the pitch can increase the production temperature and heat extraction power. The heat exchanger with a fin height of 19 mm and a pitch of 300 mm increased the heat heating temperature by 5.4 K and the heat production power by 32.4% compared with the smooth tube heat exchanger. The research results provide a theoretical basis for the design of high-efficiency coaxial borehole heat exchanger.
作者
孙琳
付必伟
魏梦辉
张思
SUN Lin;FU Bi-wei;WEI Meng-hui;ZHANG Si(College of Mechanical Engineering,Yangtze University,Jingzhou,Hubei 434023)
出处
《液压与气动》
北大核心
2023年第2期164-173,共10页
Chinese Hydraulics & Pneumatics
关键词
地热能
同轴换热器
螺旋翅片
强化传热
数值模拟
geothermal energy
coaxial heat exchangers
threaded fins
enhanced heat transfer
numerical simulation
