Numerical Simulation of Solar-Flue Gas Chimney for Energy Recovery

A solar-flue gas chimney is an energy recovery model utilizing solar energy and thermal energy from flue gas discharged from power plant to produce convective flow which drives wind turbine to generate electricity. This solar-flue gas chimney has three essential components, known as solar-flue gas collector, chimney and turbine.

Prior to the CFD simulation, the system has been modeled analytically. Numerical investigations of the flow and temperature distribution in a solar-flue gas collector have been carried out by CFD simulation. The simulation was achieved by using the commercial software, FLUENT. The simulation commenced with the actual experimental measurement conducted previously by other work. Through the simulation, this project will be presenting the thermal performance of the solar collector and elucidate how the flow and temperature distributions in the collector panel are influenced by the collector length, inlet air gap height and inlet flue gas temperature to the collector panel. Analytical investigations of the solar-flue gas collector are also analyzed out to support the results determined by numerical approach.

The simulations show that both temperature and air-flow rate almost increase linearly with the increase of heat inputs from the discharged flue gas. It indicates that the temperature of flue gas is predominant in strengthening air heating and natural convection flow for a solar-flue gas chimney. It is also found that the natural air-flow rate increases linearly with increasing inlet air gap height from 0.07m to 0.16m under identical conditions while the length of solar-flue gas chimney for 0.05m air passage height should not exceed 2.5m. Based on the investigations, recommendations are given in order to improve the collector efficiency and increase the performance of energy recovery.