| Title |
Characteristics of Evaporative Heat Transfer and Pressure Drop of Carbon Dioxide and Correlation Development near the Critical Point |
| Keywords |
Carbon dioxide ; 이산화탄소 ; Evaporative heat transfer coefficient ; 증발열전달계수 ; Pressure drop ; 압력강하 ; Correlation ; 상관식 |
| Abstract |
In recent years, carbon dioxide among natural refrigerants has gained considerable attention as an alternative refrigerant due to its excellent thermophysical properties. However, few investigations have been performed to develop useful correlations of heat transfer coefficients and pressure drop during evaporation of carbon dioxide. This study is aiming at providing the characteristics of heat transfer and pressure drop during the evaporation process of carbon dioxide. Heat is provided by a direct heating method to the test section, which was made of a seamless stainless steel tube with an inner diameter of 7.53mm, and a length of 5.0m. Experiments were conducted at saturation temperatures of －4 to 20℃, heat fluxes of 12 to 20kW/m2 and mass fluxes of 200 to 530kg/m2s. A comparison of different heat transfer correlations applicable to evaporation of carbon dioxide has been made. Based on the experiments for evaporation heat transfer and pressure drop, new correlations were developed. The newly developed empirical correlations for the heat transfer and pressure drop show average absolute deviations of 15.3% and 16.2%, respectively. |