A useful formulas to describe the performance of a steam condenser in off-design conditions

Laskowski, Rafał; Smyk, A.; Rusowicz, А.; Grzebielec, Andrzej

doi:10.1016/j.energy.2020.117910

Cited by 11 publications

(11 citation statements)

References 22 publications

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“…Our experimental condensation setup is specifically designed to test the limits of the surface coatings by exposing them to adverse conditions, which are significantly harsher (in terms of vapor temperature and pressure) compared to the ones observed in conventional industrial condensers. These usually operate with saturated steam at pressures in the range of tens of millibars and temperatures close to ambient. ,,, Moreover, the narrow channel through which steam flows in our setup additionally exposes the test surfaces to extra shear stresses (e.g., 65 mPa at 3 m/s), accelerating their degradation.…”

Section: Resultsmentioning

confidence: 99%

Metal Surface Engineering for Extreme Sustenance of Jumping Droplet Condensation

Donati,

Regulagadda,

Lam

et al. 2023

Langmuir

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Water vapor condensation on metallic surfaces is critical to a broad range of applications, ranging from power generation to the chemical and pharmaceutical industries. Enhancing simultaneously the heat transfer efficiency, scalability, and durability of a condenser surface remains a persistent challenge. Coalescence-induced condensing droplet jumping is a capillaritydriven mechanism of self-ejection of microscopic condensate droplets from a surface. This mechanism is highly desired due to the fact that it continuously frees up the surface for new condensate to form directly on the surface, enhancing heat transfer without requiring the presence of the gravitational field. However, this condensate ejection mechanism typically requires the fabrication of surface nanotextures coated by an ultrathin (<10 nm) conformal hydrophobic coating (hydrophobic self-assembled monolayers such as silanes), which results in poor durability. Here, we present a scalable approach for the fabrication of a hierarchically structured superhydrophobic surface on aluminum substrates, which is able to withstand adverse conditions characterized by condensation of superheated steam shear flow at pressure and temperature up to ≈1.42 bar and ≈111 °C, respectively, and velocities in the range ≈3−9 m/s. The synergetic function of micro-and nanotextures, combined with a chemically grafted, robust ultrathin (≈4.0 nm) poly-1H,1H,2H,2H-perfluorodecyl acrylate (pPFDA) coating, which is 1 order of magnitude thinner than the current state of the art, allows the sustenance of long-term coalescence-induced condensate jumping drop condensation for at least 72 h. This yields unprecedented, up to an order of magnitude higher heat transfer coefficients compared to filmwise condensation under the same conditions and significantly outperforms the current state of the art in terms of both durability and performance establishing a new milestone.

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Section: Resultsmentioning

confidence: 99%

Metal Surface Engineering for Extreme Sustenance of Jumping Droplet Condensation

Donati,

Regulagadda,

Lam

et al. 2023

Langmuir

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“…In off-design conditions, both the steam enthalpy at the outlet of the low pressure part of the turbine (at the condenser inlet) and the steam dryness fraction change. Changes in these properties are rather small [8], which allows us to conclude that the ratio of heat of condensing steam at the current operating point to the one in reference conditions is approximately equal to one. This assumption was verified as correct in [34].…”

Section: Mathematical Model Of a Steam Condenser 21 Equation For Cool...mentioning

confidence: 85%

“…In this context the research focuses on how a change in operating conditions, particularly the load, of generation sources affects the performance of a power generation unit. For instance, in order to ensure an optimal operation of a unit, it is examined how properties of the cooling system [1][2][3][4] (temperature and the cooling water mass flow rate) affect the performance of the condenser, the cooling system, and the whole thermal system of the unit, or how steam properties (pressure, temperature) influence the efficiency and power output of the system [5][6][7][8]. Mathematical modeling employs mainly three fundamental equations, namely the mass balance, energy balance, and moment of momentum balance, which are used to work out pressure drops.…”

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confidence: 99%

“…In [34], in order to determine cooling water temperature at the condenser outlet and steam temperature (pressure), two equations are given in the form of functions of only inlet variables, that is temperature and mass flow rate of cooling water at the condenser inlet, the steam mass flow rate, and values of these properties in reference conditions. These two proposed equations contain no constant coefficients, which makes them universal at the expense of a relatively small error of the model.…”

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confidence: 99%

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Archives of Thermodynamics

Laskowski,

Smyk,

Ruciński

et al. 2021

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The paper presents formulas which can be used to determine steam condensation pressure in a power plant condenser in off-design conditions. The mathematical model provided in the paper makes it possible to calculate the performance of the condenser in terms of condensing steam pressure, cooling water temperature at the condenser outlet, and condenser effectiveness under variable load conditions as a function of three input properties: the temperature and the mass flow rate of cooling water at the condenser inlet and the mass flow rate of steam. The mathematical model takes into account values of properties occurring in reference conditions but it contains no constant coefficients which would have to be established based on data from technical specifications of a condenser or measurement data. Since there are no such constant coefficients, the model of the steam condenser proposed in the paper is universally applicable. The proposed equations were checked against warranty measurements made in the condenser and measurement data gathered during the operation of a 200 MW steam power unit. Based on the analysis, a conclusion may be drawn that the proposed means of determining pressure in a condenser in off-design conditions reflects the condenser performance with sufficient accuracy. This model can be used in optimization and diagnostic analyses of the performance of a power generation unit.

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“…Using a simulation model and experimental data, Souza et al 12 examined two different scenarios of short-term and long-term operation of the once-through cooling water condenser system. By using the data from the literature and the manufacturer's data, Laskowski et al 13 developed a model that calculates the thermodynamic properties of cooling water. In their article, Akpan and Fuls 14 used simulation modeling to predict the pressure trend in two air-cooled and one water-cooled condensers.…”

Section: Introductionmentioning

confidence: 99%

Integration of machine learning to increase steam turbine condenser vacuum and efficiency through gasket resealing and higher heat extraction into the atmosphere

Strušnik

2021

Intl J of Energy Research

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In large thermal power facilities, thermal machines mainly fitted with steam turbines are used in thermodynamic process of converting thermal energy into mechanical work. In order to improve the efficiency of heat energy conversion into mechanical work, the increase of vacuum level in the condenser of a steam turbine was analyzed using the machine learning method. The vacuum in the steam turbine condenser increases after replacing the labyrinth gaskets with honeycomb ones, resealing the vacuum system and increasing the amount of cooling water through the condenser. The latter is controlled by algorithm, which is integrated into the steam turbine distribution control system. As a result of the increased vacuum in the steam turbine condenser, the enthalpy difference of the steam turbine low-pressure cylinder increases, and the steam turbine performs more mechanical work resulting in higher conversion efficiency. The drawback of the increased vacuum in the turbine condenser is that the flow of cooling water through the steam turbine condenser increases as well as heat dissipation from the condenser into the environment to be replaced by regenerative condensate heating. The results of the analysis show that the overall balance of the vacuum increase in the steam turbine condenser is positive, the steam turbine generates more power, and consequently the process efficiency increases by as much as 2.48 %.

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A useful formulas to describe the performance of a steam condenser in off-design conditions

Cited by 11 publications

References 22 publications

Metal Surface Engineering for Extreme Sustenance of Jumping Droplet Condensation

Metal Surface Engineering for Extreme Sustenance of Jumping Droplet Condensation

Archives of Thermodynamics

Integration of machine learning to increase steam turbine condenser vacuum and efficiency through gasket resealing and higher heat extraction into the atmosphere

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