Numerical simulation on heat transfer characteristics during waste heat utilization after the underground in-situ pyrolysis of tar-rich coal

A large amount of pyrolysis residue is left in the coal seam after the in-situ pyrolysis of tar-rich coal, which contains rich heat energy. However, there are few numerical simulations on waste heat utilization from in-situ pyrolysis of tar-rich coal at present. This paper mainly focused on the temperature field distribution and heat transfer characteristics of the coal seam in the process of waste heat utilization of tar-rich coal in large spatial scale and over a long period. The effects of cooling medium type, cooling fluid velocity, cooling fluid temperature, fracture distribution and well pattern on temperature field distribution and heat transfer performance of tar-rich coal seam were analyzed by Fluent numerical simulation. The present study can offer theoretical guidance and technical support for large-scale utilization of residual heat from pyrolysis residue of tar-rich coal.