Abstract
For improvement of reliability, the air cooling heat exchanger of natural convection type has been developed. Since the heat transfer coefficient was small in the case of natural convection flow, finned cylinders set was studied for increasing heat exchange area. However, the composition of finned cylinders set which has the maximum heat transfer coefficient is unknown, so heat exchanger design can't be performed. Then, the maximum heat transfer coefficient of finned cylinders set is investigated by examination with stuck and finned cylinders set. A result is that, when a vertical direction pitch is 5 times of fin diameter, a heat transfer coefficient is max, because of the effect between the stuck and the decreasing temperature of natural convection flow with expanding vertical pitch. As compared with 1 pipe in open space, it is conformed that finned cylinders set mean heat transfer coefficient increased by 1.6 times.
