Cooling Test Study Of Liquid CO₂ In High-Temperature Heading Face

According to the problem of thermal damage in high temperature mine at present,it has great practical significance to ensure the safety of mine production by using liquid CO2 refrigeration cooling device to cool down the high temperature mining face in coal mine.In this thesis,through the establishment of liquid CO2 refrigeration cooling device test system in high-temperature extracting coal face,cooling test study of ground liquid CO2 is carried out and the basic data of airflow temperature,static pressure difference of fan drum between internal and external,airflow velocity pressure and air atmospheric pressure are obtained.On the basis of test data,state parameters of airflow in the entrance of local fan and fluid in the fan drum are calculated according to the interaction formula.In the absence of liquid CO2 and under the condition that liquid CO2 is pumped in,in the process of air flowing,change laws of temperature,relative humidity,humidity content and enthalpy value in the fan drum are analyzed.Results show that when there is no liquid CO2,because the fan drum exits frictional heat,the temperature is increased from local fan to the entrance of first order heat exchanger,and the temperature has little change when airflow arrives at the outlet of the fan drum.Under the condition that liquid CO2 is pumped in,the airflow temperature decreases gradually in the fan drum and it reaches a good cooling effect.From the entrance of local fan to the entrance of heat exchanger,humidity content and enthalpy value increase.And after two-stage heat exchanger,humidity content and enthalpy value decrease.From the entrance of first order heat exchange to the outlet of secondary heat exchanger,with the decrease of temperature,relative humidity is significantly increased,finally approaches saturation.Fundamental test data are used to calculate gas density,wind speed,air volume and mass flow rate in the fan drum and to get the cooling capacity of heat exchanger and the exchange heat of unit liquid CO2 at different frequencies of the pressure pump.Results show that with the increase of mass flow rate of liquid CO2,the exchange heat of unit liquid CO2 begin to increase and then keeps constant basically.