The invention discloses an experimental device for observing thermal properties and structural damage of a
liquid nitrogen injected
coal body. The experimental device comprises a
drying system, a
liquid nitrogen injection
system, an exhaust
system, a pressurization system, an
infrared thermal imaging system and a crack
observation system; the
liquid nitrogen injection system, the exhaust system and the pressurization system are fixedly connected; a pressure
reducer is arranged between a liquid
nitrogen tank and a low-temperature-resistant pipeline; liquid
nitrogen is connected with a low-temperature-resistant valve through a pipeline; a liquid
nitrogen pump is arranged on the pipeline between the valve and an ultralow-temperature-resistant flowmeter; a gas flow agent and an adapter are arranged on a nitrogen
discharge pipeline; and all the system units are connected through wires. According to the experimental device for observing thermal properties and structural damage of the liquidnitrogen injected
coal body, through a liquid nitrogen injection mode, the whole
microstructure characteristics of the
coal body are changed, the primary pore fracture development and new fracture generation of the coal body are promoted, the permeability of the coal body is effectively improved, and the thermal property change and fracture development conditions of a coal sample in the liquid nitrogen injection process can be observed in real time; and
mechanical property damage conditions before and after liquid nitrogen injection of the coal sample are obtained, and quantitative describingof thermal properties and surface and internal structure damage conditions can be realized.