Research On Heat Transfer And Deposition Characteristics Of Underground Heat Exchanger In The Gold Mine

During the mining of metal mines,a large amount of gushing water has formed in deep mines,resulting in a waste of water resources and waste heat resources.The water source heat pump system using underground gushing water as the cold source can not only reuse the water inrush,but also can cool the high temperature working environment of deep mines.However,the gushing water contains certain impurities.When the gushing water flows through the water source heat pump system,fouling will be formed on the surface of the heat exchange equipment,which seriously affects the performance and service life of the equipment.However,there are many types of dirt,and the deposition process and influencing factors of dirts are complicated,so it is necessary to research the characteristics of dirt deposition under specific flow environment.Firstly,based on a large amount of water gushing underground in a gold mine,this paper selected an uphole water source heat pump system using gushing water as the cold source.Then calculated the cycle parameters and main-point parameters of the refrigeration cycle system combined with the refrigeration cycle thermodynamic process and thermodynamic properties table.The structural parameters and heat transfer parameters of the shell and tube heat exchanger were obtained by thermal calculation.Then,after establishing the three-dimensional model of shell-side fluid domain in heat exchanger based on the calculation results,this paper simulated the heat transfer and flow at different inlet velocities with ANSYS Fluent software.The results show that the fluid temperature distribution and pressure distribution correspond to the velocity distribution.The fluid flows in an"S" shape between the three processes.The fluid temperature increases and the pressure decreases gradually along the fluid flow direction.The velocity,temperature and pressure distribution are significantly different in the two sides of baffle notch.The velocity,temperature and pressure distribution are all symmetrical along the z-axis in x=0.1m,x=0.3m,x=0.5m section.In addition,the comprehensive performance parameter CP by equal pump work is used to evaluate the performance of the heat exchanger.Finally,according to the particle motion equation of Lagrangian method and momentum conservation principle,particle transport model and particle deposition model were established,meanwhile,the user defined function is compiled for the boundary condition of deposition walls and the user defined memory is used to count the number of particle deposition.Based on the numerical simulation results of heat transfer and flow of heat exchangers,this paper researched the variations of particle deposition rate in three process,the characteristics of particle deposition between different rows of tube bundles,and the distribution characteristics of the upper and lower sides of the tube bundles in different inlet flow rates and particle size conditions with ANSYS Fluent software.The results show the total particle deposition rate decrease as inlet velocity and particle size increase.The total particle deposition rate in the second process is greater than that in the third process at different speeds and particle sizes,while the particle deposition rates are different between the inlet process and the second or third process within the range of different particle sizes.The particle deposition between the rows of tube bundles in the three process has a non-linear characteristic.The variation of the deposition amount between the rows of tube bundles is different in three processes,which is mainly affected by particle size.The position of pipe row with the maximum deposition amount is affected by inlet velocity and particle size.When the inlet flow velocity is small,the deposition of large-diameter particles in each process between various tube bundles is more affected by the baffle notch.Besides,particles are mainly deposited on the upper side of the tube bundle at different inlet velocity and particle size.When the inlet velocity is identical,the proportion of particle deposition on the lower side of each row of tube bundles decreases with increase of particle size.When the inlet velocity increases,the deposition distribution of particles of different sizes on the upper and lower sides of tube bundles is different.