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 (NTU L ), and total volume heat transfer coefficient (K V ) 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 NTU L . It is discovered that NTU L and K V can be expressed by dimensionless parameters of flow and temperature, and that the empirical correlations of NTU L and K V agree well with experimental data. K E Y W O R D Scocurrent flow packed tower, direct-contact condensation, exhaust steam condensation, number of liquid-phase heat transfer units, subcooling, total volume heat transfer coefficient

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Condensers are often required in power generation systems to condense the exhaust steam generated at the end of the turbine. This paper will investigate the enhanced condensation process of spent steam in a parallel flow type. The operating parameters of steam temperature (Tcond), steam flow rate (Gin), cooling water temperature (Tin), and cooling water flow rate (Lw) will affect the condensation effect by changing the gas–liquid arrangement in the tower. In this experiment, an orthogonal test was designed in the Raschig ring to investigate the significance of these four operating parameters on the experimental results. Different types of packings have different condensation effects due to different accumulation methods. The same type of packing has a different surface area, resulting in different contact areas between the gas and liquid phases during condensation. In this experiment, four different packings will be investigated to find their condensation performance. This paper uses the size of subcooling (ΔT) as an indicator to evaluate the effectiveness of condensation, and the values of condensation rate (R), number of liquid phase heat transfer units (NTUL), and total volume heat transfer coefficient (Kv) are used as a reference for the effectiveness of condensation. The results show that the overall condensation effect of regular packing is better than that of random packing, The average condensation rate of regular packing is 95%, the average condensation rate of random packing is 90%, the subcooling of regular packing is about three to five smaller than that of random packing, the heat transfer coefficient of regular packing is about 1.5 times of that of random packing. And by fitting the Kv data for different packings, an empirical formula was obtained that can be used to predict the Kv size of other packings.