Experimental investigation on phase transition and heat transfer characteristics for liquid carbon dioxide in loose coal

In order to investigate heat transfer characteristics of LCO2 injected in loose coal and study influence of injection parameters on temperature field of coalꎬ experiments on LCO2 injection process were carried out by using self ̄made test platform. Thenꎬ temperature changes of coal and influence of injection parameters on refrigeration range were analyzed. The results show that when LCO2 is injected into loose coalꎬ phase transition occurs immediatelyꎬ and an intensive heat transfer process starts and forms a phase ̄ change cooling area (<-56􀆰 6 °C) which sees a logarithm increase over injection time in direction of CO2 jet. Meanwhileꎬ the cooling area increases in a form of exponentialꎬ logarithm and linear function respectively along with increase of injection flowꎬ caliber and pressure.