HEAT TRANSFER ENHANCEMENT BY TWISTED TAPE INSERTS DURING CONDENSATION OF R-245fa INSIDE A HORIZONTAL TUBE

摘要

An experimental investigation has been made to study the enhancement of heat transfer coefficient during condensation of the pure vapor of R-245fa inside a horizontal tube by inserting twisted tap of different twist ratio in the range of 4.3 to 6.4. For each inserted tube and the plain tube, the data were acquired for mass fluxes in the range of 100 kg/m~2·s to 200 kg/m~2·s for the entire range of vapor quality from 0.1 to 0.9. The twisted tape is more effective at the low mass flux and in low vapor quality region as compared to high vapor quality region. The highest enhancement of heat transfer is 25 percent above the plain flow for the twist ratio of 4.3 at refrigerant mass flux of 100 kg/m~2·s.