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Analysis of heat flow in a tube bank of a condenser considering the influence of air

Joachimiak M., Joachimiak D., Krzyślak P.

Archives of Thermodynamics

2017

Vol. 38, no. 3

119--134

The pressure of wet water vapor inside a condenser has a great impact on the efficiency of thermal cycle. The value of this pressure depends on the mass share of inert gases (air). The knowledge of the spots where the air accumulates allows its effective extraction from the condenser, thus improving the conditions of condensation. The condensation of water vapor with the share of inert gas in a model tube bank of a condenser has been analyzed in this paper. The models include a static pressure loss of the water vapor/air mixture and the resultant changes in the water vapor parameters. The mass share of air in water vapor was calculated using the Dalton’s law. The model includes changes of flow and thermodynamic parameters based on the partial pressure of water vapor utilizing programmed water vapor tables. In the description of the conditions of condensation the Nusselts theory was applied. The model allows for a deterioration of the heat flow conditions resulting from the presence of air. The paper contains calculations of the water vapor flow with the initial mass share of air in the range 0.2 to 1%. The results of calculations clearly show a great impact of the share of air on the flow conditions and the deterioration of the conditions of condensation. The data obtained through the model for a given air/water vapor mixture velocity upstream of the tube bank allow for identification of the spots where the air accumulates.

Study of the effectiveness of the turbine condenser air extraction system using hydro ejectors

Badur J., Kowalczyk T., Ziółkowski P., Tokarczyk P., Woźniak M.

Transactions of the Institute of Fluid-Flow Machinery

2016

nr 131

41--53

The aim of the paper is to investigate the effectiveness of the 18K380 steam turbine condenser air extraction system using hydro ejectors. Motivation for the analysis was a need of improvement of the energy conversion ratio of the power plant. To achieve this goal it was necessary to establish efficiency of each subsystem of the energy cycle. The air extraction system is not a highly power consuming system but it has great impact on the steam cycle efficiency by influence on the condensation temperature. The air extraction system effectiveness depends on a weather conditions, exactly on the ambient temperature, which raises the question whether it is worth to modernize the hydro ejectors or replace them by a centrifugal vacuum pumps. To establish the vacuum system effectiveness a new innovative mass flow measuring system has been implemented to measure an air-steam mixture flow and the fraction of the air mass in the mixture. The measuring system is based on a Venturi nozzle supplemented with a temperature drop during the mixture expansion.