Flow and heat transfer characteristics study of supercritical CO 2 in horizontal semicircular channel for cooling process

摘要

Heat transfer and pressure drop characteristics of supercritical CO2in horizontal semicircular channels was investigated numerically. Comparison study of flow and heat transfer characteristics of semicircular and circular channels at the same inlet velocity and mass flux was conducted respectively with the bulk temperature ranging from 27?°C to 67?°C. It is shown that the fluid heat transfer coefficient and pressure drop in the circular channel are slightly higher than those of the semicircular channel, but the fluid temperature drop through the circular channel is lower than that of the semicircular channel under the same hydraulic diameter. The effect of heat flux and channel hydraulic diameters on the heat transfer coefficient and pressure drop was analyzed for horizontal cooling semicircular channels. It is found that smaller hydraulic diameter enhances heat transfer, but the channel flow resistance increases significantly. The numerical results also indicate that the pressure drop decreases with the increase of heat flux, and the heat transfer coefficients depend on both bulk temperature and cooling heat flux.