Study Of Heat-Mass Transfer And Thermal Efficiency On Heat Recovery Of Mine Return Air

The underground coal mining return air contains a lot of low-grade heat, it can be extracted and supplied to the end user by using the return air heat recovery system consisted by spray heat source devices coupled with heat pump system. In summer, the recovery system spray devices is equivalent to central air-conditioning cooling towers; in winter, sprinkler extracts return air heat and the recovery system is equivalent to the heat source, which can reduce or replace the boiler. At the same time, the way of spray water for heat can reduce dust in airflow, which can reduce the emission. Therefore, the return air heat recovery system has important practical significance in the mining area of "energy saving"The purpose of this paper is to study the mine return air heat recovery, on the basis of existing research theoretical, though experimental and numerical simulation methods researching the spray in mine return air, which has provided a theoretical basis and experimental basis for the engineering application.The key part of the design of heat recovery system is the design and application of the thermal spray section. Firstly, the main study of paper is the spray heat exchanger, using theories of heat transfer, heat and mass transfer principles and the air-conditioning heat to analysis the process of heat and moisture exchange between air and water within the sprinkler in theoretically, and deduced the dimensionless formula of heat transfer efficiency, and using Matlab software to calculate the influence of partial factors on efficiency of heat transfer for the recovery of design, test and engineering application, which provides a theoretical basis. Then using similar theory of fluid mechanics, heat transfer to design and build a mine return air heat recovery simulation platform, and based on the theoretical analysis results, using it to do experimental study for the main factors. The experiment studied the effects of heat transfer efficiency, heat exchange and water temperature after heat exchange in the different amounts of water, air flow, vapor ratio and spray height. Study has shown that the impact of water amount, water vapor are more prominent than the height in exchange efficiency, and all of them have influence on the temperature of the exchanged heat.