流下液膜式プレートフィン蒸発器内でのHFO-1233zd(E)の蒸発熱伝達

抄録

In the present study, the characteristics of heat transfer are experimentally investigated on the falling film evaporation of alternative pure refrigerant HFO1233zd(E) in a plate-fin heat exchanger consisting of serrated-fins. The refrigerant liquid is supplied to the channel through 37 holes of a distributor. The liquid flowing down vertically is heated electrically from the rear wall of the channel and evaporated. The experimental parameters are set as follows: the mass velocities are varied 7.4~55.1 kg/(m²s), the heat fluxes are varied 8.7~50 kW/m² and the pressures are about 100~150 kPa. In the case of small mass velocity being smaller than 20 kg/(m²s), the heat transfer coefficient decreases monotonously and gradually in accordance with an increase in vapor quality, taking value of 6~1kW/m²K. It is thought that the value of heat transfer coefficient decreases due to dry patch and the spread of a dry part in the downstream region. In the case of mass velocity being larger than 41 kg/(m²s), the values of heat transfer coefficient vary 8~22 kW/m²K in the region with the vapor quality 0～0.3. In the following region, the values are distributed around 10 kW/m²K. The relations between vapor quality and fin efficiency are investigated to examine the effectiveness of fins brazed to the base plate.