Design of a Coal Drying System with Solar-Assisted Heat Pump and Waste Heat Utilisation

The increase in global energy demand has directed researchers towards making low-quality coals into an environmentally friendly energy source by reducing their high moisture content. Drying coal is a high-energy and time-consuming process, so reducing the required energy and drying time is crucial for drying technology. Coal drying increases the thermal value of coal and makes it easier to transport. In this study, a coal drying system was designed using waste heat recovery systems, R-134a refrigerant as working fluid, air source heat pumps, and vacuum tube solar collectors to provide hot air. Firstly, the moisture content of the coal and the desired moisture content after drying were determined, and then the heat required to dry the coal was calculated. Next, the capacity of the solar collector required to provide the necessary heat to the heat pump was determined, and the type and capacity of the heat pump that could produce the required heat were selected. Finally, the coal dryer was designed based on the specific requirements of the power plant and the type of coal used. As a result, the coal drying system designed with solar-assisted heat pumps and waste heat utilization can increase the efficiency of coal-fired power plants by reducing the moisture content of coal before combustion.