Thermal Performance Analysis on shell-and-tube heat exchangers by Utilizing Liquid Carbon Dioxide for Mine Cooling

Abstract

ABSTRACT Liquid carbon dioxide (LCO2) shows great potential in mitigating heat damage in high-temperature mines. To address cooling needs of mine working faces, a shell-and-tube heat exchanger utilizing LCO2 was designed and relevant performance parameters were analyzed. After analyzing 290 sets of experimental data, we compared 7 heat transfer models and pressure drop correlations for predicting CO2 two-phase flow, among which the lowest prediction errors are 23.7% and 18.8%, respectively. By adapting variable thermal properties of LCO2 from NIST (National Institute of Standards and Technology), the appropriate parameter size for the heat exchanger has been obtained through detailed iterative solutions. The various influencing factors were investigated as well. The results show that increasing the outside diameter from 9 mm to 10 mm and decreasing the baffle spacing from 140 mm to 100 mm significantly improves the heat transfer performance. However, the inner diameter and the mass flow rate have a greater impact on pressure drop than heat transfer, with final pressure drops of 5.9 kPa, 12.1 kPa, and 27.1 kPa, respectively. This work can serve as a foundation for further investigations on CO2 utilization and provide technical guidance for the design of LCO2 shell-and-tube heat exchangers.