Abstract
Liquid CO2 can absorb heat via phase change and generates cryogenic CO2 which can effectively solve the problem of thermal damage in the deep coal mining process. The CO2 cycle refrigeration device system is designed to effectively cool down the working surface of the mine in which CO2 is cyclically utilized. COMSOL Multiphysics simulation software is used to characterize the CO2 cycle refrigeration system in mine of the heat transfers process between CO2 and the air flow in tunnel. The results show that the reduction of steady air flow temperature reach at 8 °C in the tunnel by CO2 cycle refrigeration system before the air flow into work face. we analyzed the influence of main parameters on refrigeration system and gets the results:1) The refrigeration system get higher cooling efficiency of cryogenic CO2 when the ventilation velocity of local fan is increased, and the temperature of outlet CO2 and steady air flow in tunnel has increased; 2) Increasing the CO2 flow, the refrigeration effect of the system is enhanced obviously, but CO2 refrigeration capacity utilization ratio is reduced; 3) Increasing the length of helical tube would led to use CO2 refrigerating capacity more efficiently; 4) The cooling effect of the cooling system can be improved obviously by lowering the the CO2 cooling temperature.
Highlights
With the increases in the depths of mines, hightemperature mines have been more and more [1]
A high-temperature environment directly affects mineworkers in work condition and work efficiency, and is easy to cause insecure behavior and lack of enthusiasm [2]. It will seriously endanger the health of workers that working in a high temperature environment for a long time [3]
There is a duct with a radius of 0.6 m in the tunnel, which is supplied by a local fan with wind air of 5 m/s
Summary
With the increases in the depths of mines, hightemperature mines have been more and more [1]. Guo Pingye et al has designed a refrigeration systems which used the cold water as the cold source, and established evaluation method for mine refrigeration system to optimizes the refrigeration system and improve the cooling effect of the working face [8,9] This system needs a lot of cold water from the ground as refrigeration. The processes of heat exchange between the CO2 and air flow or thermal diffusion in mine are less reported These are the critical processes for the refrigeration system which determine the cooling effect for the work face, refrigeration efficiency and working cost of the refrigeration system. To analyze the process of heat exchange between CO2 and the air flow as well as the influence of main parameters on the cooling effect, a cooling model of CO2 refrigeration in mine is established in this paper. Where Re is the Reynolds number; e is the surface roughness; d is the pipe diameter, m
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