Experimental investigation on direct‐contact condensation of subatmospheric pressure steam in cocurrent flow packed tower

Abstract

Abstract Exhaust steam condensation equipment is an important component in thermal power generation systems. Direct‐contact condensation offers high heat transfer efficiency, small flow resistance, simple structure, and less scaling; therefore, its application to exhaust steam condensation equipment is conducive to reducing equipment investment and operation costs. In this study, the direct‐contact condensation of subatmospheric pressure steam (exhaust steam) is investigated in a cocurrent flow packed tower. The effects of steam temperature, steam flow, cooling water temperature, and cooling water flow on the condensation rate, subcooling, number of liquid‐phase heat transfer units (NTUL), and total volume heat transfer coefficient (KV) are investigated. The results show that the direct‐contact condensation of exhaust steam can yield a high condensation rate, low subcooling, and good stability in the cocurrent flow packed tower. Lower steam temperature, higher steam flow, higher inlet‐water temperature, and lower water flow are conducive to the increase in NTUL. It is discovered that NTUL and KV can be expressed by dimensionless parameters of flow and temperature, and that the empirical correlations of NTUL and KV agree well with experimental data.

Keywords

• cocurrent flow packed tower
• direct‐contact condensation
• exhaust steam condensation
• number of liquid‐phase heat transfer units
• subcooling
• total volume heat transfer coefficient