고분자 첨가제에 의한 OTEC용 판형 열교환기의 마찰 저항 감소 연구

초록

Experimental investigation has been cvarried out to find drag reducing effects by polymer additives in the flow of plate type heat exchangers (evaporator or condenser) for OTEC power plant applications, where the pressure drop in the heat exchangers takes up 70~80% of the total pumping power in the existing system. The rate of drag reduction was investigated with various polymer concentrations and mass flow rates. Experiments were ubdertaken with a test section of Alfa-Laval plate heat exchanger (model: CB26-24) and Poly Ethylene Oxide (Mw=5.0E6) as polymer additives were utilized with 5, 10, 20, 30, 40, 50, 100, 200, 400, wppm at 25C. Mass flow rate were 0.6, 0.7, 0.8, and 0.9 kg/s for normal operating ranges in the 15 kW Alfa-Laval plate type heat exchanger. The maximum efects of drag reductions were found that at approximately 0.7 kg/s of mass flow rate. The results show that there exists the optimum mass flow rate for the plate type heat exchanger for maximum drag reductions. Drag reduction of 20% suggests considerable savings in pumping power for large size of OTEC plant.