평활관 및 마이크로핀관내 이산화탄소의 응축열전달 특성

Abstract

The condensation heat transfer coefficients of CO2 in smooth and micro-fin tubes were investigated experimentally. The main components of the refrigerant loop are a receiver, a pump, a mass flow meter, a preheater and a condenser(test section). The water loop consists of a pump, an flow meter. The test sections used as condenser was made of tube-in-tube type heat exchanger, which consisted of concentric tube. There are a micro-fin tube with 4.6 mm inner diameter and smooth tube with 4.95 mm inner diameter. and are divided into two equal horizontal straight of 2400 mm. The range of parameters of mass flux were varied from 800 to 2000 kg/m2s, saturation temperature were 20～30℃, inlet quality were 1～0. The average condensing heat transfer coefficient from 2 tube was presented the maximum value in the tube of the high quality. The average condensing heat transfer coefficient have an effect on the mass flux of R744. The average condensing heat transfer coefficient was presented the maximum value in the tube of the high mass flux. The average condensing heat transfer coefficient have an effect on the saturation temperature and tube shape. The average condensing heat transfer coefficient was presented the maximum value of the low saturation temperature and microfin tube. Comparing the condensing heat transfer coefficient between experimental result and simulation data, the Shah's correlation yielded better closed correlation than other results in smooth tube and the Cavallini's correlation yielded better closed correlation than other results in microfin tube. Therefore, it is necessary to develop reliable and accurate predictions determining the condensation heat transfer coefficient of CO2 in the micro-fin tube.