| Title |
An Experimental Study on the Characteristics of Evaporative Heat Transfer of Carbon Dioxide |
| Keywords |
Natural refrigerant(천연냉매), Carbon dioxide(이산화탄소 ; Evaporative heat transfer coefficient ; 증발열전달계수 ; Direct heating ; 직접 가열 |
| Abstract |
Evaporative heat transfer characteristics of carbon dioxide have been investigated by experiment. The experiments have been carried out for a seamless stainless steel tube of the outer diameter of 9.55 mm, the inner diameter of 7.75 mm and the length of 5.0 m. Direct heating method was used for supplying heat to the refrigerant where the test tube was uniformly heated by electric current which was applied to the tube wall. Experiments were conducted with CO2 of purity 99.99% at saturation temperatures of 0.0 to 10.5℃, heat fluxes of 12 to 27 kW/m2 and mass fluxes of 212 to 530 kg/m2s. The heat transfer coefficients of CO2 are decreased as the vapor quality increases and these phenomena are explained by dimensionless Weber and Bond numbers. The heat transfer coefficients of CO2 increase when the heat and mass fluxes increase, and the saturation temperature effects are minor in the test range of this study. The present experimental data are compared with six renowned correlations with root-mean-squared deviations ranging from 23.0 to 94.9% respectively. |