Influence Of Gravity Heat Pipe Arrangement And Working Medium Type On Coal Pile Temperature Field

Coal is one of the important energy sources in China.In recent years,China’s demand for coal has been increasing.However,since most of the coal in our country has the tendency of spontaneous combustion,the phenomenon of spontaneous combustion of coal piles often occurs in the process of coal storage and transportation.Gravity heat pipes have excellent thermal conductivity.Using gravity heat pipes to destroy the heat storage environment inside the coal pile is a new idea to control the spontaneous combustion of coal storage piles.Based on the principle of gravity heat pipe heat transfer,this paper analyzes the process of gravity heat pipe restraining coal pile spontaneous combustion,and independently builds a coal pile-gravity heat pipe test bench.By means of numerical simulation and experimental analysis,the influence of the layout parameters of gravity heat pipes on the temperature field inside the coal pile is studied,and the working efficiency of gravity heat pipes with different working fluids at different coal pile temperatures is studied by means of experiments.Arrange28 temperature measuring points in the coal pile,and monitor the internal measurement of the coal pile by inserting gravity heat pipes at different depths(40 cm,50 cm,60 cm)and at different angles(30°,45°,60°,90°).The temperature changes at 24 h were analyzed,and the influence of the arrangement of gravity heat pipes on the temperature field of the coal pile was analyzed.The gravity heat pipe of the type of potassium chromate solution)was used to monitor the temperature change of the measuring points in the coal pile for 24 hours,and the influence of the working medium of the gravity heat pipe on the temperature field of the coal pile was analyzed.In this paper,by establishing a coal pile-gravity heat pipe test bench model,and using Comsol software to simulate it,it is found that when the gravity heat pipe insertion depth is60 cm and the insertion angle is 60°,the cooling effect of the gravity heat pipe is improved.optimal.The cooling range of the gravity heat pipe is proportional to the insertion depth,and the insertion angle and cooling effect are in the order of 60°>90°>45°>30°,and the cooling effect increases first and then decreases with the change of angle.The cooling radius of the gravity heat pipe is proportional to the insertion depth.The results show that when the insertion depth is 60 cm,the cooling radius is the largest,which is 49 cm.Through experiments to compare the cooling effects of different working medium gravity heat pipes on coal piles at different coal pile temperatures,it is found that the cooling range,cooling radius and heat extraction of gravity heat pipes in the coal pile are proportional to the coal pile temperature.When the coal pile temperature is 95 At ℃,the cooling sequence of gravity heat pipe with different working fluids is acetone>methanol>ethanol>water>potassium dichromate solution working fluid gravity heat pipe,the acetone gravity heat pipe has the best cooling effect on coal piles within 24 h,and the maximum cooling rate is 1.75 ℃/ h.When the coal pile temperature is 120 ℃,the cooling order of different`working medium gravity heat pipes is methanol>acetone>ethanol>water>potassium dichromate solution working medium gravity heat pipe,the methanol gravity heat pipe has the best cooling effect on the coal pile within 24 h,The maximum cooling rate was 2.4 °C/h.The comprehensive comparison shows that the optimal heat pipe parameters in this paper are selected as follows: the best working medium gravity heat pipe is selected as methanol gravity heat pipe,the insertion depth is 60 cm,and the insertion angle is 60°.This paper provides a reference for the selection of gravity heat pipes and their arrangement in the coal pile.