A Study on a Heat Transfer Characteristics of Direct Contact Heat Exchanger for Steam Condensation According to Various Cooling Water Flow and Internal Pressure(The Purpose of Combination with LNG Evaporator)

증기응축용 직접접촉식 열교환기의 냉각수 유량과 내부압 변화에 따른 열전달 특성연구(LNG 기화기와의 조합목적)

Heat transfer characteristics of a direct contact heat exchanger utilizing sieve trays and spray nozzles for steam condensation for the purpose of combining with a LNG evaporator have been investigated with various cooling water flow rates and different vacuum pressures within the heat exchanger for the purpose of steam condensation. Temperature profiles and the volumetric overall heat transfer coefficients in a direct contact heat exchanger have been obtained for comparisons. The results show that the temperature differences between cooling water and steam along the direct contact heat exchanger height are rapidly decreasing and the volumetric overall heat transfer coefficients of the exchanger improves greatly as the inside vacuum pressure increases. The values of the overall heat transfer coefficients at P=-680mmHg have been increased significantly compared with at atmospheric pressure. At given pressure conditions, it is found that the values of average volumetric overall heat transfer coefficients for the sieve tray are found to be approximately 10% higher than those of the spray nozzle.