Performance of vertical tube passive condenser with the effects of noncondensable and secondary cooling water

An experimental work was carried out on a passive containment cooling system (PCCS) test facility where the effects of change in secondary cooling pool water level and the presence of a noncondensable on the PCCS heat transfer characteristics were investigated. Two condensation flow regimes, complete condensation and flow-through condensation relevant to initial and late stages of PCCS operation, were investigated where secondary cooling pool water level decreases with time. A single tube and a tube bundle test section were used. Steady-state tests with half full and half secondary pool levels were performed using single and four-tube bundle test sections. Transient tests were carried out on the tube bundle test section where the secondary pool water decreases continuously due to boil-off. Transient tests carried out with secondary pool water level change showed that the system pressure for complete condensation mode increases with decrease in water level; however, rate of condensation is almost constant. If the PCCS is operated in through-flow mode the system pressure (primary side pressure) is constant; however, the condensate rate decreases, indicating that some of the steam does not condense. A decrease in pool water level to the top header initially decreases the inlet steam pressure, indicating slight heat transfer enhancement due to efficient cooling of PCCS tubes due to two-phase mixture. When the water level is below three-fourths of the tube height the inlet steam pressure increases with decrease in the water level, indicating decrease in PCCS heat transfer rate. The presence of a noncondensable also reduced PCCS condensation heat transfer.