ねじりテープを挿入した水平管内沸騰熱伝達と圧力降下の実験的研究

抄録

This paper aims to investigate the effect of heat transfer enhancement and tube shortening in the evaporator of the air conditioner by using twisted-tape insert. The evaporator is a counter-flowing tube-in-tube heat exchanger and a refrigerant R410A in an inner copper tube is heated by water in an annular passage. Experiments have been conducted in a 17.05mm ID and 1 m length test section containing twist-tape for twist-ratios of 3.3, 3.9 and 5.1 under various conditions of the refrigerant mass flux, the heat flux in the heat exchanger and the vapor quality. Data on heat transfer and pressure drop coefficients in the test section were obtained to discuss the effectiveness of twisted tape insert in the evaporator of the air conditioner. Furthermore, in order to show the effect of the twisted tape on the flow pattern of the refrigerant, the flow was visualized at the inlet and outlet of the test section.