Journal articles: 'Condensers (Steam) Heat'

1

Lv, Yi, Hui Zhang, Yu Jin Yue, Li Jun Yang, and Xiao Dong Zhang. "Deviation Analysis on Flow and Heat Transfer Model of Large Air-Cooled Steam Condenser Unit." Advanced Materials Research 860-863 (December 2013): 656–62. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.656.

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Many power plants adopt air-cooled condensers (ACC) with finned tubes, using ambient air to condense turbine exhaust steam. Each condenser unit is mainly composed of two heat transfer surfaces like A and large diameter axial flow fans driving air. In the study of environmental wind effects, etc, due to the condenser unit size is bigger, it is necessary to simplify the condenser unit internal flow and heat transfer calculation, but the deviations introduced by these simplifies failed to get enough attention. In view of one condenser unit, three kinds of flow and heat tansfer combinated model were respectively investigated. A computational fluid dynamics software (CFD) is used to solve the problem.Research priority is analyzing the deviations of internal flow and heat transfer features in the condenser unit according to the extracted datum. The study gives some useful informatin to the design of a thermal power plant with an ACC system.

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Zhang, C., A. C. M. Sousa, and J. E. S. Venart. "Numerical Simulation of Different Types of Steam Surface Condensers." Journal of Energy Resources Technology 113, no. 2 (June 1, 1991): 63–70. http://dx.doi.org/10.1115/1.2905788.

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A numerical procedure is developed to simulate the fluid flow and heat transfer processes in the shell-side of steam surface condensers. The governing equations are solved in primitive variable form using a semi-implicit consistent control-volume formulation in which a segregated pressure correction linked algorithm is employed. The procedure is applied to three different types of surface condenser. The numerical predictions are critically assessed by comparison to available experimental data for condensers, and in general, the solutions are in good agreement with the experimental data.

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Zhang, C., and Y. Zhang. "A Quasi-Three-Dimensional Approach to Predict the Performance of Steam Surface Condensers." Journal of Energy Resources Technology 115, no. 3 (September 1, 1993): 213–20. http://dx.doi.org/10.1115/1.2905996.

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A quasi-three-dimensional numerical procedure is proposed to simulate the fluid flow and heat transfer in the shell-side of steam surface condensers. The proposed procedure is applied to an experimental steam surface condenser to evaluate its predictive capability. The predicted results give good general agreement with the experimental data. The governing equations are solved in primitive variable form using a semi-implicit consistent control-volume formulation in which a segregated pressure correction linked algorithm is employed. The modeling of the geometries of condensers, including tube bundles and baffle plates, is carried out based on porous media concepts using flow, heat and mass transfer resistances.

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Wang, Si Ping, Li Zhang, and Jian Li. "The Numerical Simulation of the Shell Side Flow and Heat Transfer for 600MW Steam Turbine Condenser." Advanced Materials Research 614-615 (December 2012): 265–71. http://dx.doi.org/10.4028/www.scientific.net/amr.614-615.265.

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Detailed prediction of steam flow field and heat transfer process is significant for the condensers. The flow and heat transfer performance of the condenser of 600MW power unit is numerical simulated. A model of porous media with distributed resistance and mass sink is used to simulate the function of the tube bundle. The equations including the continuous, momentum and air concentration are numerically solved using the finite control-volume integration method and SIMPLE algorithm. The distribution of steam velocity, pressure, heat transfer coefficient and air concentration are obtained and analyzed. On the basis of results, the condenser is evaluated.

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Kals, W. "Condensing the Dumped Steam During a Turbine Bypass." Journal of Engineering for Gas Turbines and Power 114, no. 4 (October 1, 1992): 621–31. http://dx.doi.org/10.1115/1.2906635.

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The reaction of water-cooled and wet-surface air-cooled condensers to a bypass of the steam turbine is analyzed by the introduction of an indicant. Gas dynamics considerations for designing the breakdown of the steam pressure are included. SI metric units are compared with gravitational metric units in order to clarify the fundamental difference between these two systems of measure. Conditioning the steam before admission to the condenser involves desuperheating, which is analyzed on the basis of a heat balance.

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Papini, Davide, and Antonio Cammi. "Modelling of Heat Transfer Phenomena for Vertical and Horizontal Configurations of In-Pool Condensers and Comparison with Experimental Findings." Science and Technology of Nuclear Installations 2010 (2010): 1–16. http://dx.doi.org/10.1155/2010/815754.

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Decay Heat Removal (DHR) is a fundamental safety function which is often accomplished in the advanced LWRs relying on natural phenomena. A typical passive DHR system is the two-phase flow, natural circulation, closed loop system, where heat is removed by means of a steam generator or heat exchanger, a condenser, and a pool. Different condenser tube arrangements have been developed for applications to the next generation NPPs. The two most used configurations, namely, horizontal and vertical tube condensers, are thoroughly investigated in this paper. Several thermal-hydraulic features were explored, being the analysis mainly devoted to the description of the best-estimate correlations and models for heat transfer coefficient prediction. In spite of a more critical behaviour concerning thermal expansion issues, vertical tube condensers offer remarkably better thermal-hydraulic performances. An experimental validation of the vertical tube correlations is provided by PERSEO facility (SIET labs, Piacenza), showing a fairly good agreement.

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Ni, Weiming, Zhihua Ge, Lijun Yang, and Xiaoze Du. "Piping-Main Scheme for Condensers against the Adverse Impact of Environmental Conditions on Air-Cooled Thermal Power Units." Energies 13, no. 1 (December 30, 2019): 170. http://dx.doi.org/10.3390/en13010170.

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To improve the adaptability of direct air-cooled power generating units to the variations of both meteorological condition and power load, a piping-main arrangement of air-cooled condensers was proposed. The heat and mass transfer models of the air-side were established for the air cooling system of 2 × 600 MW thermal power generating units. The coupled model for both flow resistance loss and condensate flow rate distributions of exhaust steam inside air-cooled condensers were developed based on the temperature fields through numerical simulation. Calculation results, including the condensate flow rate, back pressure, and coal consumption rate, were acquired under different ambient temperatures and wind velocities. The results show that the proposed piping-main arrangement can weaken the ambient wind impacts and reduce the backpressure significantly in summer by adjusting the number of air-cooled condenser cells in operation. The steam flow rate can be uniformed effectively by adjusting the number of operating air-cooled condenser cells during winter. It can also avoid the freezing accident in winter while cooling the exhaust steam of two turbines by part air-cooled condenser cells.

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Feng, Huijun, Wei Tang, Lingen Chen, Junchao Shi, and Zhixiang Wu. "Multi-Objective Constructal Optimization for Marine Condensers." Energies 14, no. 17 (September 5, 2021): 5545. http://dx.doi.org/10.3390/en14175545.

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A marine condenser with exhausted steam as the working fluid is researched in this paper. Constructal designs of the condenser are numerically conducted based on single and multi-objective optimizations, respectively. In the single objective optimization, there is an optimal dimensionless tube diameter leading to the minimum total pumping power required by the condenser. After constructal optimization, the total pumping power is decreased by 42.3%. In addition, with the increase in mass flow rate of the steam and heat transfer area and the decrease in total heat transfer rate, the minimum total pumping power required by the condenser decreases. In the multi-objective optimization, the Pareto optimal set of the entropy generation rate and total pumping power is gained. The optimal results gained by three decision methods in the Pareto optimal set and single objective optimizations are compared by the deviation index. The optimal construct gained by the TOPSIS decision method corresponding to the smallest deviation index is recommended in the optimal design of the condenser. These research ideas can also be used to design other heat transfer devices.

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Davies, William A., Yu Kang, Pega Hrnjak, and Anthony M. Jacobi. "Heat transfer and flow regimes in large flattened-tube steam condensers." Applied Thermal Engineering 148 (February 2019): 722–33. http://dx.doi.org/10.1016/j.applthermaleng.2018.11.079.

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10

Valentinovich Kurshakov, Alexander, Artem Vyacheslavovich Ryzhenkov, Valerij Dmitrievich Burov, Oleg Vyacheslavovich Ryzhenkov, and Marat Ravilevich Dasaev. "Heat Transfer Enhancement in Condensers in Steam Turbine Based Combined Heat and Power Plants." Biosciences, Biotechnology Research Asia 12, Special-Edn2 (September 25, 2015): 617–23. http://dx.doi.org/10.13005/bbra/2241.

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11

Kayansayan, N. "The gravity assisted heat pipe with application to concrete shell steam condensers." Journal of Heat Recovery Systems 6, no. 5 (January 1986): 389–97. http://dx.doi.org/10.1016/0198-7593(86)90226-2.

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12

Dronov, Dmitry M., Aleksandr V. Gontovoy, Yelena N. Sarkisyan, and Natalya V. Karandeeva. "Experience of using the NALCO 1392 scale inhibitor in the circulating water supply system of the Novovoronezh NPP." Nuclear Energy and Technology 7, no. 2 (June 21, 2021): 85–89. http://dx.doi.org/10.3897/nucet.7.68940.

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Power facilities use large amounts of water to cool steam in the steam turbine condensers, and lubricating oils, gas and air in turbine sets. The key requirement for the quality of cooling water is to ensure normal vacuum in condensers. Cooling water must not form mineral and biological deposits and corrosion products in the system. Deposits of mineral salts in the condenser tube system, as well as in auxiliary cooling systems, lead to deterioration in heat exchange and a major decrease in the cost effectiveness of the power equipment operation, and require the heat-exchange equipment to be periodically cleaned. The source water used for cooling is normally taken from nearby water bodies (large rivers or lakes). Circulating water supply systems are used most commonly: these systems use repeatedly the same water inventory for cooling, and require only small amounts of water added to make up for evaporation losses. Coolers, in this case, are cooling towers, spray pools and evaporation ponds. The water chemistry should ensure the operation of equipment without any damage to its components or the loss of efficiency caused by the corrosion of the internal surfaces as well as without scale and sludge formation. It is exactly when using circulating water supply that a stabilizing treatment program is the most practicable way to ensure a cost-effective and environmentally friendly mode of operation. To inhibit scaling processes on the heat-exchange surfaces of the turbine condenser tubes at the Novovoronezh NPP’s unit 5, the cooling water was treated with the NALCO 1392 inhibitor. The results of the NALCO 1392 inhibitor pilot tests in the circulating water supply system (with a cooling pool) are presented.

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13

Hu, Hong Gang, and Chao Zhang. "A New Inundation Correlation for the Prediction of Heat Transfer in Steam Condensers." Numerical Heat Transfer, Part A: Applications 54, no. 1 (April 16, 2008): 34–46. http://dx.doi.org/10.1080/10407780802024963.

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14

Rachman, Arfidian, and Lisa Nesti. "Experimental Study to Performance Improvement of Vapor Compression Cooling System Integrated Direct Evaporative Cooler and Condenser." MATEC Web of Conferences 215 (2018): 01017. http://dx.doi.org/10.1051/matecconf/201821501017.

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For areas with very hot and humid weather condition increased latent and sensible load are a major problem in cooling systems that will increase compressor work so that electricity consumption will also increase. Combined condenser with direct evaporate cooling will increase the heat removal process by using an evaporative cooler effect that will increase the efficiency of energy use. This paper presents the study of the use of evaporator cooling and condenser. This paper mainly calculated energy consumption in steam compression cooling systems and related problems. From the results of this study, the use of condensers with evaporative cooling, power consumption can be reduced to 46% and performance coefficient (COP) can be increased by about 12%, with 1,2 kW cooling capacity.

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Shavdinova, Madina, Konstantin Aronson, and Nina Borissova. "Development of condenser mathematical model for research and development of ways to improve its efficiency." Journal of Applied Engineering Science 18, no. 4 (2020): 578–85. http://dx.doi.org/10.5937/jaes0-27517.

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The condensing unit is one of the most important elements of the steam turbine of a combined heat and power plant. Defects in elements of the condensing unit lead to disturbances in the steam turbine operation, its failures and breakdowns, as well as efficiency losses of the plant. Therefore, the operating personnel need to know the cause of the malfunction and to correct it immediately. There are no diagnostic models of condensers in the Republic of Kazakhstan at the moment. In this regard, a mathematical model of a condenser based on the methodology of Kaluga Turbine Plant (KTP) has been developed. The mathematical model makes it possible to change the input parameters, plot dependency diagrams, and calculate the plant efficiency indicators. The mathematical model of the condenser can be used to research ways for the improvement of the condensing unit efficiency, for diagnostic purposes of the equipment condition, for the energy audit conduction of the plant, and in the training when performing virtual laboratory research. Using static data processing by linear regression method we obtain that the KTP methodology of condenser calculation is fair at cooling water temperature from 20 °C to 24 °C, but at cooling water temperature from 20 °C to 28 °C, the methodology of JSC "All-Russia Thermal Engineering Institute" (JSC "VTI") is used. One of the ways to increase the condenser efficiency has been proposed. It is the heat transfer augmentation with riffling annular grooves on tubes. This method increases the heat transfer coefficient by 2%, reduces the water subcooling of the heating steam by 0.9 °C, and decreases the cooling area by 2%.

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WANG, ZHONG-ZHENG, and ZHEN-NAN ZHAO. "Analysis of Performance of Steam Condensation Heat Transfer and Pressure Drop in Plate Condensers." Heat Transfer Engineering 14, no. 4 (January 1993): 32–41. http://dx.doi.org/10.1080/01457639308939809.

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17

ZHANG, CHAO, and YING ZHANG. "Sensitivity Analysis of Heat Transfer Coefficient Correlations on the Predictions of Steam Surface Condensers." Heat Transfer Engineering 15, no. 2 (January 1994): 54–63. http://dx.doi.org/10.1080/01457639408939824.

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Kurshakov, A. V., A. V. Ryzhenkov, A. A. Bodrov, O. V. Ryzhenkov, A. A. Patakin, and E. F. Chernov. "Heat transfer enhancement in steam-turbine condensers with the use of surface-active substances." Thermal Engineering 61, no. 11 (October 9, 2014): 785–89. http://dx.doi.org/10.1134/s0040601514110020.

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19

Dobkiewicz-Wieczorek, Ewa. "Influence of three surface condensers connection setup on power plant unit performance." E3S Web of Conferences 137 (2019): 01027. http://dx.doi.org/10.1051/e3sconf/201913701027.

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This paper presents a comparison of three surface condenser connection setups on the cooling water side. Serial, mixed and parallel connections were considered. The thermodynamic justification for the use of more complex configurations was verified. The analysis was conducted based on the calculated heat balances of verified power units for nominal and not nominal parameters for tested connections. The exhaust steam pressure was calculated using the technical data of the surface condenser and cooling water parameters. Three methods of calculating the heat transfer coefficient based on characteristic numbers, HEI method, and the ASME standard, were used. The most advantageous model was indicated and used in heat balance calculations. The assumptions and simplifications for the calculations are discussed. Examples of the calculation results are presented.

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Jun, Yong-Du, Kwang J. Kim, and John M. Kennedy. "Dynamic surface tension of heat transfer additives suitable for use in steam condensers and absorbers." International Journal of Refrigeration 33, no. 2 (March 2010): 428–34. http://dx.doi.org/10.1016/j.ijrefrig.2009.11.006.

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Davies, William A., Yu Kang, Pega Hrnjak, and Anthony M. Jacobi. "Effect of inclination on heat transfer and flow regimes in large flattened-tube steam condensers." Applied Thermal Engineering 148 (February 2019): 999–1006. http://dx.doi.org/10.1016/j.applthermaleng.2018.11.078.

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Kim, Nae-Hyun, and Min-Geon Go. "Tube-side heat transfer and friction characteristics of titanium corrugated tubes used for steam condensers." Journal of Mechanical Science and Technology 32, no. 9 (September 2018): 4535–43. http://dx.doi.org/10.1007/s12206-018-0850-0.

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23

Mahvi, Allison J., Alexander S. Rattner, Jennifer Lin, and Srinivas Garimella. "Challenges in predicting steam-side pressure drop and heat transfer in air-cooled power plant condensers." Applied Thermal Engineering 133 (March 2018): 396–406. http://dx.doi.org/10.1016/j.applthermaleng.2018.01.008.

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Davies, William A., and Pega Hrnjak. "Heat transfer and flow regimes during counter-flow steam condensation in flattened-tube air-cooled condensers." International Journal of Heat and Mass Transfer 147 (February 2020): 118930. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2019.118930.

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Papp, L., and S. S. Chen. "Turbulence-Induced Vibration of Tube Arrays in Two-Phase Flow." Journal of Pressure Vessel Technology 116, no. 3 (August 1, 1994): 312–16. http://dx.doi.org/10.1115/1.2929594.

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Two-phase flow exists in many engineering systems and is a dominant type of flow in heat exchangers, steam generators, and condensers. A flowing two-phase fluid is a source of energy that can cause vibration of tube bundles of these systems. A simple correlation is presented to predict the response of tube bundles in two-phase flow. The model correlates with experimental data reasonably well and is a useful tool in the prediction of tube response.

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Petrovic, Anka. "Analytical Study of Flow Regimes for Direct Contact Condensation Based on Parametrical Investigation." Journal of Pressure Vessel Technology 127, no. 1 (February 1, 2005): 20–25. http://dx.doi.org/10.1115/1.1845471.

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Various industrial devices exist where direct contact condensation (DCC) of steam in water takes place. Typical examples are the nuclear reactor coolant systems, steam driven jet pumps, and condensers. The modeling of steam condensation is crucial to obtain an appropriate design of such devices. Present models designed for DCC have shown limited agreement with experimental data. Computation of the flow regimes is performed with limited accuracy, due to initial model settings and empirical correlations, which form a main drawback in the computation of DCC related problems. This study, which is a part of a PhD study, presents an investigation of the steam-water interface for various conditions of steam and water, using the computation of balance equations and jump conditions. A simple mathematical model to predict the location of the condensation interface for four different shapes of steam plume at different heat transfer coefficients is presented which will be further developed into an advanced computational model for DCC.

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Taylor, C. E., and M. J. Pettigrew. "Random Excitation Forces in Heat Exchanger Tube Bundles." Journal of Pressure Vessel Technology 122, no. 4 (March 7, 2000): 509–14. http://dx.doi.org/10.1115/1.1286040.

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Random excitation forces can cause low-amplitude tube motion that will result in long-term fretting-wear or fatigue. To prevent these tube failures in heat exchangers, designers and troubleshooters must have guidelines that incorporate random or turbulent fluid forces. Experiments designed to measure fluid forces were conducted at the Chalk River Laboratories and at other laboratories worldwide. The data from these experiments were studied and collated, to determine suitable guidelines for random excitation forces. In this paper, a guideline for random excitation forces in single-phase cross flow is presented in the form of normalized spectra that are applicable to a wide range of flow conditions and tube frequencies. In particular, the experimental results used in this study were conducted over the full range of flow conditions found in the liquid region of a nuclear steam generator. The proposed guidelines are applicable to steam generators, condensers, reheaters and other shell-and-tube heat exchangers. They may be used for flow-induced vibration analysis of new or existing components, as input to vibration analysis computer codes and as specifications in procurement documents. [S0094-9930(00)00603-X]

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Davies, William A., and Pega Hrnjak. "Local heat transfer coefficient during stratified flow in large, flattened-tube steam condensers with non-uniform heat flux and wall temperature." International Journal of Heat and Mass Transfer 146 (January 2020): 118854. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2019.118854.

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Pettigrew, M. J., and C. E. Taylor. "Damping of Heat Exchanger Tubes in Two-Phase Flow: Review and Design Guidelines." Journal of Pressure Vessel Technology 126, no. 4 (November 1, 2004): 523–33. http://dx.doi.org/10.1115/1.1806443.

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Two-phase flow exists in many shell-and-tube heat exchangers such as condensers, evaporators, and nuclear steam generators. Some knowledge on tube damping mechanisms is required to avoid flow-induced vibration problems. This paper outlines the development of a semi-empirical model to formulate damping of heat exchanger tube bundles in two-phase cross flow. The formulation is based on information available in the literature and on the results of recently completed experiments. The compilation of a database and the formulation of a design guideline are outlined in this paper. The effects of several parameters such as flow velocity, void fraction, confinement, flow regime and fluid properties are discussed. These parameters are taken into consideration in the formulation of a practical design guideline.

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Pettigrew, M. J., J. H. Tromp, and J. Mastorakos. "Vibration of Tube Bundles Subjected to Two-Phase Cross-Flow." Journal of Pressure Vessel Technology 107, no. 4 (November 1, 1985): 335–43. http://dx.doi.org/10.1115/1.3264461.

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Two-phase cross-flow exists in many shell-and-tube heat exchangers such as condensers, reboilers and nuclear steam generators. Thus we are conducting a comprehensive program to study tube bundle vibrations subjected to two-phase cross-flow. This paper presents the results of experiments on a normal-triangular and a normal-square tube bundle, both of p/d = 1.47. The bundles were subjected to air-water mixtures to simulate realistic vapor qualities and mass fluxes. Vibration excitation mechanisms were deduced from vibration response measurements. Results on damping, hydrodynamic mass, fluid-elastic instability and random turbulence excitation in two-phase cross-flow are presented.

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Au-Yang, M. K., R. D. Blevins, and T. M. Mulcahy. "Flow-Induced Vibration Analysis of Tube Bundles—A Proposed Section III Appendix N Nonmandatory Code." Journal of Pressure Vessel Technology 113, no. 2 (May 1, 1991): 257–67. http://dx.doi.org/10.1115/1.2928753.

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This paper presents guidelines for flow-induced vibration analysis of tubes and tube bundles such as those commonly encountered in steam generators, heat exchangers, condensers and nuclear fuel bundles. It was proposed as a nonmandatory code to be included in Section III Appendix N (N-1300 series) of the American Society of Mechanical Engineers (ASME) Boiler Code. In preparing this code, the authors tried to limit themselves to the better-defined flow excitation mechanisms—vortex-induced vibration, fluid-elastic instability and turbulence-induced vibration—and include only the more-established methods. References are, however, given for other methods whenever justified. This guideline covers only design analysis. A companion guideline on the testing and data analysis of heat exchanger tube banks was proposed as part of the ASME Code on Operations and Maintenance of Nuclear Plants. The latter is not included in this paper.

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Hajduk, Tomasz. "Research of Deposit Accumulated on Heat Exchange Surfaces in the Light of Thermal Degradation of Heat Exchange Aparatus of Steam Power Plants Part I: Study of Real Sediments." Polish Maritime Research 25, no. 1 (March 1, 2018): 99–107. http://dx.doi.org/10.2478/pomr-2018-0012.

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Abstract The presence of deposits on heat exchange surfaces in condensers and regenerative exchangers of ship and land steam power plants is always connected with the increase of the wall temperature on the water vapor side due to additional thermal resistances resulting from accumulated deposits. This increase always results in an increase in the condensing pressure, which results in the deterioration of the condensation process of the water vapor, leading to thermal degradation of a given heat exchanger. In addition, the resulting deposits form unevenness with a diversified, often stochastic, geometric structure of the surface layer surface, whose measure is most often the roughness parameters, describing the geometric structure of the surface. In addition, the increase in surface roughness of the heat transfer surface on the water vapor side promotes the formation of a thicker layer of condensate, thus worsening the organization of condensate runoff, which results in interference of the thermal degradation phenomenon of a given heat exchange apparatus. As a result, these phenomena lead to a reduction in the efficiency of a given thermal system, and thus entail an increase in the costs of energy conversion and consequently cause an increased degradation of the natural environment. In the article, based on the results of the author’s own experimental research, the types of pollution accumulating on heat exchange surfaces on the water vapor side of heat exchange apparatus in marine and land steam power plants and quantitative measures of the unevenness of the surface layer of these sediments are presented.

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Virji, M. B. V., and R. H. Thring. "Analysis of a 50 kWe indirect methanol proton exchange membrane fuel cell (PEMFC) system for transportation application." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 219, no. 8 (August 1, 2005): 937–50. http://dx.doi.org/10.1243/095440705x34694.

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Steady state and dynamic models of proton exchange membrane fuel cell (PEMFC) or solid polymer fuel cell (SPFC) systems have been developed for transport and stationary applications. This paper reports the results of a steady state analysis of a methanol-fuelled PEMFC vehicle with a maximum (electrical) power output of 50 kW. The model incorporates a methanol steam reformer, gas clean-up unit, fuel cell stack, compressor, expander, battery pack, and heat exchangers as well as electrical power handling, motor, gearbox, and final drive. Results are given for the reformer as a function of steam-carbon ratio and reformer temperature. A degree of optimization of the system was conducted by (a) the addition of preheat to the reformer and burner reactants and (b) the addition of condensers for the fuel cell exhaust gases. The effect of operating pressure was also investigated. It was concluded that only by proper thermal integration could the target electrical system efficiency of better than 45 per cent at rated power be achieved.

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Vodeniktov, A. D., V. G. Vlasenko, and N. D. Chichirova. "Improvement of efficiency of detecting vacuum leakages by using combined methods." Vestnik IGEU, no. 3 (June 30, 2021): 13–21. http://dx.doi.org/10.17588/2072-2672.2021.3.013-021.

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Trouble-free operation of the main equipment of heat power plants is determined by the performance reliability of condensing units. High air density of the vacuum system provides cost-effective and reliable operation. One of the reasons that causes an increase of the exhaust steam pressure compared to the standard pressure, in addition to contamination of the condensers cooling surface, is the high amount of air inflow through vacuum system leakiness. Exceeding the amount of atmospheric air inflow into the vacuum system above the standard value, both reduces the available heat energy and make worse the deaeration capacity of the condenser. This results in saturation of the full-flow condensate with oxygen and intensification of corrosion processes. Various methods varying in both cost and efficiency are used to find air inflow location. Nowadays, the issue of choosing a method to detect even the most insignificant air inflow location of the vacuum system of a steam turbine remains open. In the current study, the authors have used the thermal-imaging method to detect air inflow location due to local hypocooling, and the ultrasonic method, which is based on the detection of ultrasound created by gas flows. The authors have proved the necessity to use several different in concept methods to find leakage locations in a vacuum system. It is established that traditional methods to find vacuum system leaks do not allow to eliminate excess leaks. In-service monitoring confirms 87 % reduction of the amount of vacuum leaks. The studies show high efficiency of sharing both thermal imaging and ultrasonic methods to detect air inflow location in a vacuum system. According to the operating conditions of the available equipment, as well as the personnel qualifications, the results obtained make it possible to choose the most optimal way in terms of financial and time expenses to find vacuum leakage location in the vacuum system of a steam turbine.

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Taylor, C. E., and M. J. Pettigrew. "Effect of Flow Regime and Void Fraction on Tube Bundle Vibration." Journal of Pressure Vessel Technology 123, no. 4 (July 10, 2001): 407–13. http://dx.doi.org/10.1115/1.1403024.

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Two-phase cross flow occurs in industrial heat exchangers such as condensers, boilers, and steam generators. Under certain flow regimes and fluid velocities, the fluid forces result in tube vibration and possibly tube damage due to fretting or fatigue. Prediction of these fluid forces requires an understanding of the flow regimes found in heat exchanger tube bundles. Measurements of void fraction within a tube array were taken as an initial step in determining the two-phase flow patterns. The tests were conducted in a Freon 134a test loop at about 1 MPa and 30°C. The measurements were compared against void fraction models commonly used in heat exchanger thermalhydraulic simulation codes and against available flow regime maps. Not surprisingly, the results indicate that a drift-flux model more accurately predicts the void fraction within a tube array. The measurements also confirm the existence of nonuniform void fraction radially around the tube. Based on these measurements and available literature, appropriate void fraction models for use in flow-induced vibration design guidelines are discussed.

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Małek, Marcin, Marcin Wachowski, and Robert Kosturek. "Research on microstructure and mechanical properties of explosively welded stainless steel/commercially pure Ti plate." Manufacturing Review 6 (2019): 28. http://dx.doi.org/10.1051/mfreview/2019028.

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Surface protection by the application of explosive welding is one of the meaningful methods used in many chemical devices like reactor condensers, heat exchangers, steam turbines and other processing apparatus. Due to the wide range of explosively welded applications, the problem of the useful lifetime of the products obtained by this method becomes important and should be well understood. Process of explosive welding is related to enormous pressure and high detonation velocity, which causes intense energy release in a short time, which favors to produce solid wavy bond featured with high metallurgical quality. Due to strain hardening in the bond zone, significant changes in microstructures and mechanical properties were observed. In this paper, 316L stainless steel explosively welded with commercially pure titanium was investigated to show the correlations and changes between microstructures and mechanical properties before and after annealing. Application of post-weld heat treatment contributes to stress relieving and improves the mechanical properties, which is closely related to microstructure recrystallization and hardness decrease adjacent to joint.

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Esayah, Amna, Madison Kelley, Andrew Howell, Stephen J. Shulder, Brajendra Mishra, David Olson, and Jason Porter. "Flow Accelerated Corrosion of Carbon Steel with Droplet Impingement Using a Modified Rotating Cylinder Electrode Experiment." Corrosion 76, no. 2 (January 5, 2020): 202–9. http://dx.doi.org/10.5006/3345.

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In power plant cooling systems, water droplets and condensate films form due to heat transfer through cooling tube walls. Condensate films are known to cause flow accelerated corrosion on carbon steels used in air-cooled condensers. Corrosion is further accelerated by droplets suspended in the accelerating steam that impinge on walls, T-joints, or valves, further damaging protective oxide layers on pipe walls. Droplet impingement and flow accelerated corrosion were studied using a modified rotating cylinder electrode system coupled with electrochemical impedance spectroscopy. Surface liquid films caused by droplet impingement were found to correlate directly with flow accelerated corrosion caused by condensate films. In the absence of a stable liquid film, droplet impingement increased corrosion rates and resulted in pit formation. Select corrosion inhibitors were found to be ineffective under flow accelerated corrosion or droplet impingement.

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Lobachyov, K. V., and H. J. Richter. "Addition of Highly Efficient Bottoming Cycles for the Nth-Generation Molten Carbonate Fuel Cell Power Plant." Journal of Energy Resources Technology 119, no. 2 (June 1, 1997): 103–8. http://dx.doi.org/10.1115/1.2794972.

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An intermediate scale (2.0 MW gross) molten carbonate fuel cell (MCFC) power plant recently began operating in Santa Clara, California. The goal of the project is to demonstrate the possibility of long-term operation of MCFC stacks. The fuel cell stacks are the only source of electricity, which means a simple power plant system, and relatively low capital costs. This, however, results in substantial work losses in the plant, most of which come from the hot exhaust gas discharge. The predicted efficiency is a respectable 50 percent. In this paper, an exergy analysis is performed in order to study if a future plant’s efficiency can be improved. It is shown that for the future plant of this type it would be worthwhile to consider the addition of a steam bottoming cycle as well as changing the configuration of the top cycle. This can lead to improving the efficiency to close to 70 percent. The modified power plant requires additional equipment, such as steam turbines, heat exchangers, condensers; thus, the capital cost of the plant changes substantially. A cost analysis of the modified plant was performed, and a comparison of the cost of electricity between the two cycles is made. Finally, a Kalina cycle as one option for a bottoming cycle is considered as well.

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Morghi, Youssef, Jesus Puente, Amir Mesquita, and Ana Baliza. "INVESTIGATION OF COUNTER-CURRENT FLOW LIMITATION FOR AIR-WATER IN A PWR HOT LEG EXPERIMENTAL LOOP FOR DIFFERENT GEOMETRY." International Journal of Engineering Technologies and Management Research 5, no. 2 (February 10, 2020): 198–212. http://dx.doi.org/10.29121/ijetmr.v5.i2.2018.164.

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Gas/liquid two-phase stratified flows in horizontal channels are frequently encountered in nuclear reactors, oil and gas pipelines, steam generators, refrigeration equipment, reflux condensers, packed columns, and heat pipes. The phenomenon known as countercurrent flow limitation, or flooding, is the limiting condition where the flow rates of neither the gas nor the liquid can be further increased without changing the flow pattern. This is the condition where the maximum air mass flow rate at which the down-flowing water mass flow rate is equal to the inlet water mass flow rate. This limiting condition, also known as onset of flooding, can occur in vertical or horizontal geometry. This work is a review of recent experimental investigations of countercurrent flow limitation (CCFL) for various hot-leg geometries of pressurized water reactors (PWRs). We compare results with those obtained from the Nuclear Technology Development Centre (CDTN) in 2005. Recent experimental results in the literature are in good agreement with the 2005 findings.

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Chiou, W. A., N. Kohyama, B. Little, P. Wagner, and M. Meshii. "TEM study of a biofilm on copper corrosion." Proceedings, annual meeting, Electron Microscopy Society of America 54 (August 11, 1996): 220–21. http://dx.doi.org/10.1017/s0424820100163563.

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The corrosion of copper and copper alloys in a marine environment is of great concern because of their widespread use in heat exchangers and steam condensers in which natural seawater is the coolant. It has become increasingly evident that microorganisms play an important role in the corrosion of a number of metals and alloys under a variety of environments. For the past 15 years the use of SEM has proven to be useful in studying biofilms and spatial relationships between bacteria and localized corrosion of metals. Little information, however, has been obtained using TEM capitalizing on its higher spacial resolution and the transmission observation of interfaces. The research presented herein is the first step of this new approach in studying the corrosion with biological influence in pure copper.Commercially produced copper (Cu, 99%) foils of approximately 120 μm thick exposed to a copper-tolerant marine bacterium, Oceanospirillum, and an abiotic culture medium were subsampled (1 cm × 1 cm) for this study along with unexposed control samples.

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Yang, Li, Yunfeng Ren, Zhihua Wang, Zhouming Hang, and Yunxia Luo. "Simulation and Economic Research of Circulating Cooling Water Waste Heat and Water Resource Recovery System." Energies 14, no. 9 (April 27, 2021): 2496. http://dx.doi.org/10.3390/en14092496.

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Industrial circulating cooling water contains a large amount of low-quality energy, which is lost to the environment through cooling towers. It is of great significance and potential to recover the waste heat to improve energy-saving effects and economic efficiency. However, the effect of common water harvesting and energy saving devices is not significant. Heat pumps have been shown to be effective in improving low-quality heat energy in energy conversion systems, although there are not many applications of heat pump scenarios in engineering practice. Based on this, a recovery solution of circulating cooling water waste heat and water resource using lithium bromide absorption heat pump has been put forward. The energy-saving performance of the recovery system was simulated and analyzed using Aspen Plus V10.0 (Bedford, MA, USA) to explore the effects of the parameters of the working medium in evaporators, condensers, absorbers, generators, heat exchangers, etc., and the modelling results indicated that the evaporation pressure and temperature have a great influence on the system COP (coefficient of performance) and can raise the thermal economy of the system. The heat from driving steam and heating capacity both increased with the increase in generating temperature, while the increase in temperature difference between evaporation and condensation inhibits the COP of heat pump systems. Furthermore, economic analyses and comparisons of the recovery solutions were conducted and the recovery solution of circulating cooling water waste heat with heat pump had the best economic performance due to the annual income from the recovery of waste heat and water resource. The static payback period results indicate that the recovery solution from circulating cooling water waste heat with a heat pump has better economic performance than the scenario with a cooling tower. The waste heat recovery solution with a heat pump can improve the thermal economy of the system and has a great guiding significance for engineering practice.

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Klimov, R., and V. Kirilyuk. "EFFICIENCY OF THE NOZZLES OF CONTACT HEAT EXCHANGERS." Collection of scholarly papers of Dniprovsk State Technical University (Technical Sciences) 1, no. 38 (September 8, 2021): 92–98. http://dx.doi.org/10.31319/2519-2884.38.2021.11.

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At powerful thermal power plants or boiler houses, the efficiency depends to the greatest extent on the amount of heat lost with the cooling of turbine condensers, exhaust gases that have a high temperature. Each type of such losses is a large unused energy potential, that is, a secondary energy resource that can be used. At the same time, the use of secondary resources and industrial emissions will improve the ecological situation in the regions, and this has always been an urgent task. As a rule, large losses of thermal secondary energy resources in boilers are reduced by installing economizers and air heaters. Contact types of heat exchangers are distinguished by the best efficiency in operation. In contact economizers, to increase the surface of heat and mass transfer, it is advisable to use various types of nozzles. The aim of the study is to develop such an indicator, with which it is possible to determine the optimal type of nozzle of the contact economizer installed after the steam boiler. This indicator should show the highest heat engineering efficiency of the packing with a small hydraulic resistance of the heat exchanger. By using the coefficient of specific energy efficiency of the packing in the heat exchanger of waste gases of heating equipment, it is possible to analyze the work of the packing space from the standpoint of thermal and hydraulic efficiency and select the optimal type of packing for each individual unit or installation. Geometric parameters determine the required volume of the apparatus and the hydraulic resistance of the exhaust gases movement. The hydraulic resistance affects the consumption of electrical energy for the drive of smoke exhausters for sucking off exhaust gases from heat engineering installations through the free section of the heat exchanger. Taking into account the developed indicator of the specific energy efficiency in waste heat utilizers, it is possible to select such a type of packing, at which the optimal level of waste heat utilization will be achieved.

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Zoder, Marius, Janosch Balke, Mathias Hofmann, and George Tsatsaronis. "Simulation and Exergy Analysis of Energy Conversion Processes Using a Free and Open-Source Framework—Python-Based Object-Oriented Programming for Gas- and Steam Turbine Cycles." Energies 11, no. 10 (September 30, 2018): 2609. http://dx.doi.org/10.3390/en11102609.

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State-of-the-art thermodynamic simulation of energy conversion processes requires proprietary software. This article is an attempt to refute this statement. Based on object-oriented programming a simulation and exergy analysis of a combined cycle gas turbine is carried out in a free and open-source framework. Relevant basics of a thermodynamic analysis with exergy-based methods and necessary fluid property models are explained. Thermodynamic models describe the component groups of a combined heat and power system. The procedure to transform a physical model into a Python-based simulation program is shown. The article contains a solving algorithm for a precise gas turbine model with sophisticated equations of state. As an example, a system analysis of a combined cycle gas turbine with district heating is presented. Herein, the gas turbine model is validated based on literature data. The exergy analysis identifies the thermodynamic inefficiencies. The results are graphically presented in a Grassmann chart. With a sensitivity analysis a thermodynamic optimization of the district heating system is discussed. Using the exergy destruction rate in heating condensers or the overall efficiency as the objective function yields to different results.

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Pettigrew, M. J., C. E. Taylor, and B. S. Kim. "Vibration of Tube Bundles in Two-Phase Cross-Flow: Part 1—Hydrodynamic Mass and Damping." Journal of Pressure Vessel Technology 111, no. 4 (November 1, 1989): 466–77. http://dx.doi.org/10.1115/1.3265705.

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Two-phase cross-flow exists in many shell-and-tube heat exchangers, such as condensers, reboilers and nuclear steam generators. An understanding of damping and of flow-induced vibration excitation mechanisms is necessary to avoid problems due to excessive tube vibration. Accordingly, we have undertaken an extensive program to study the vibration behavior of tube bundles subjected to two-phase cross-flow. In this paper we present the results of experiments on four tube bundle configurations; namely, normal triangular of pitch over diameter ratio, p/d, of 1.32 and 1.47, and parallel triangular and normal square of p/d of 1.47. The bundles were subjected to air-water mixtures to simulate realistic mass fluxes and vapor qualities corresponding to void fractions from 5 to 99 percent. Hydrodynamic mass and damping are discussed in Part 1 of this series of three papers. We found that hydrodynamic mass is roughly related to the homogeneous mixture density. The damping characteristics of all tube bundles are generally similar. Damping is maximum between 40 and 80 percent void fraction where the damping ratio reaches about 4 percent. The effect of mass flux is generally weak. Design guidelines are proposed for hydrodynamic mass and for damping.

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Hidayat, Muhammad Rizky, and Aqli Mursadin. "ANALISIS PERPINDAHAN PANAS GLAND STEAM CONDENSOR DI PT PJB UBJOM PULANG PISAU KALTENG." JTAM ROTARY 2, no. 2 (September 29, 2020): 207. http://dx.doi.org/10.20527/jtam_rotary.v2i2.2416.

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Gland Steam Condensor (GSC) adalah alat penukar panas yang mengembunkan uap dari segel poros turbin. Steam bekas ini akan memanaskan air kondensat dari pompa kondensat yang dialirkan melintasi kondensor Gland Steam. Karena panas diserap oleh air kondensat, maka steam bekas dari seal poros akan mengembun kemudian dialirkan ke hotwell hingga bercampur dengan air hotwell. Dari hasil penelitian koefisien perpindahan kalor tertinggi pada tabung adalah 80.491,93 btu/hr ft2 pada hari Rabu jam 14.00. Diketahui bahwa koefisien perpindahan panas pada tabung terendah adalah 79.011,94 btu/hr ft2 pada hari Senin jam 16.00. Koefisien perpindahan panas tertinggi pada cangkang adalah 5.294.695 btu/jam ft2 pada hari Jumat pukul 14.00, koefisien perpindahan panas cangkang terendah adalah 2.762.553 btu/jam ft2 pada hari Selasa pukul 11.00. Perpindahan panas aktual tertinggi adalah 1.528.694.1 btu/jam hari Jumat jam 14.00, perpindahan panas aktual terendah adalah 713.159.522 btu/jam pada hari Kamis jam 8.00. Diketahui laju perpindahan kalor maksimum sebesar 1.797.918 btu/jam pada pukul 14.00, laju perpindahan kalor maksimum sebesar 790.348 btu/jam pada hari Kamis pukul 08.00. Diketahui efisiensi tertinggi sebesar 90,25% pada hari Kamis pukul 08.00. Dengan efisiensi rata-rata antara kisaran 86,29%. Gland Steam Condensor (GSC) is a heat exchanger it condenses steam from a turbine shaft seal. This used steam will heat condensate water from a condensate pump which is flowed across Gland Steam condensor. Because the heat is absorbed by condensate water, used steam from the shaft seal will condense and then flow to hotwell until it mixes with hotwell water. From the results of the study the highest heat transfer coefficient on the tube is 80,491.93 btu/hr on Wednesday at 2:00 p.m. It is known that the heat transfer coefficient on the lowest tube is 79,011.94 btu/hr on Monday at 4:00 p.m. The highest heat transfer coefficient on the shell is 5,294,695 btu/hr on Friday at 14:00, the lowest shell heat transfer coefficient is 2,762,553 btu/hr on Tuesdayat 11: 00. The highest actual heat transfer is 1,528,694.1 btu/hr on Friday at 2:00 p.m., the lowest actual heat transfer is 713,159,522 btu/hr on Thursday at 8:00. It is known that the maximum heat transfer rate is 1,797,918 btu/hr at 2:00 p.m., the maximum heat transfer rate is 790,348 btu/hr on Thursday at 8:00. It is known that the highest efficiency is 90.25% on Thursday at 8:00. With average efficiency between the range of 86.29%.

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Priambodo, Dedy, Erlan Dewita, and Ign Djoko Irianto. "ANALISIS ENERGI DAN EKSERGI PADA SISTEM HTR-10 SIKLUS TURBIN UAP." Jurnal Pengembangan Energi Nuklir 17, no. 1 (June 14, 2015): 33. http://dx.doi.org/10.17146/jpen.2015.17.1.2561.

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ABSTRAK ANALISIS ENERGI DAN EKSERGI PADA SISTEM HTGR SIKLUS TURBIN UAP. Reaktor tipe HTGR merupakan reaktor yang rencana akan dibangun sebagai Reaktor Daya Eksperimental (RDE) pertama di Indonesia. Reaktor HTGR merupakan reaktor dengan suhu pendingin keluar reaktor tinggi (686°C ~ 950°C), efisiensi termal tinggi serta mempunyai sistem keselamatan pasif dan melekat. Untuk mengetahui ketepatan efisiensi suatu pembangkit dipandang tidak cukup jika hanya mengacu pada efisiensi energi saja seperti yang didasarkan pada Hukum I Termodinamika, namun perlu dikombinasikan dengan pendekatan eksergi yang berdasarkan Hukum II Termodinamika. Karena itu, tujuan studi adalah melakukan analisis energi dan eksergi pada sistem HTGR siklus turbin uap untuk mengetahui kerugian/ kehilangan panas yang terjadi dalam komponen sistem pembangkit, sehingga dapat diketahui potensi-potensi kerugian dan dapat dilakukan perbaikan. Metodologi yang digunakan adalah perhitungan menggunakan program cycle tempo dengan input data dari reaktor HTR-10. Hasil studi analisis dan evaluasi terhadap ireversibilitas sistem reaktor HTGR menggunakan siklus turbin uap menunjukkan bahwa reaktor merupakan komponen yang paling tidak efisien diantara seluruh komponen yang ada dalam sistem. Hal ini disebabkan ireversibilitas yang terjadi dalam transfer energi hasil reaksi pembelahan ke pendingin helium. Pembangkit uap, turbin, kondensor, adalah komponen penyumbang kerugian terbesar berikutnya. Hasil studi juga menunjukkan bahwa efisiensi sistem HTGR siklus turbin uap mempunyai potensi besar untuk dilakukan perbaikan sehingga mampu memberikan efek yang signifikan terhadap perbaikan efisiensi sistem. Kata kunci: energi, eksergi, HTGR, analisis, turbin uap ABSTRACT ENERGY AND EXERGY ANALYSIS ON THE STEAM TURBINE CYCLE OF HTGR SYSTEM. HTGR type reactor is planned to be built reactors as the first Experimental Power Reactor (RDE) in Indonesia. HTGR tipe reactor is a reactor with a high reactor outlet temperature (~ 900 ° C), high thermal efficiency and also it have inherent and passive safety systems. To determine the accuracy of the efficiency of a power plant is not enough if it merely refers to the energy efficiency just as it is based on the first law of thermodynamics, but it needs to be combined with exergy approach that is based on the second law of thermodynamics. Therefore, the purpose of the study is to analyze the energy and exergy of HTGR-steam turbine cycle system to determine the loss / heat loss that occurs in the power system components, so it can be seen the potential loss and can be repaired. The methodology used is a calculation using the program cycle due to the data input of the HTR-10 reactor. The results of analysis and evaluation of the irreversibility of HTGR reactor system using a steam turbine cycle shows that the reactor is a component of the least efficient among all components in the system. This is due to the irreversibility of energy transfer that occurs in the cleavage reaction proceeds to the helium coolant. Steam generators, turbines, condensers, is a component of the next largest contributor kerugia. The study shows that the efficiency of the steam turbine cycle HTGR system has great potential to be improved so it can provide a significant effect on the improvement of the efficiency of the system. Keywords: energy, exergy, HTGR, analysis, steam turbine

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Kosasih, E. A., R. I. Wahid, and A. A. Faros. "Aquadest production system as steam turbine bottom cycle II: influence of condenser pressure and pinch point temperature difference." E3S Web of Conferences 67 (2018): 04029. http://dx.doi.org/10.1051/e3sconf/20186704029.

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Most of the energy derived from Steam turbine is discharge in the condenser at temperatures that may damage the environment. The condenser cooling water has gone through water treatment process, so it would be better used as raw material to produce aquadest. This study simulate a system that produces aquadest by throttling 10% of cooling water that coming out the condenser into a vacuum chamber (3 kPa). The resulting cold vapoor is condensed in the evaporator become aquadest. Cold water coming out the vacuum chamber is mixed with water coming out the condenser is lower than before. Parameters that varied are the condenser pressure and pinch point temperature difference (PPTD) inside the condenser. The simulation resulted the condenser cooling water temperature of less than 40 °C (design point), especially at PPTD of 9 °C. that applicable to all variations of condenser pressure 7 to 12 [kPa]. Spesific energy consumption of aquadest are between 550,7 to 900,3 [kPa] (less than half of water evaporation heat) and the aquadest flowrate are between 0,116 to 0,319 [kg/s].

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Fan, Jun, and Feng Zhong Sun. "Analysis on Chilled Water Spraying through Extraction Opening in Condenser to Enhance Extraction Effect of Vacuum Pump." Advanced Materials Research 860-863 (December 2013): 737–41. http://dx.doi.org/10.4028/www.scientific.net/amr.860-863.737.

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Non condensable gas (air) accumulating in the condenser will reduce heat transfer coefficient of condense and vacuum value, Reducing of condenser vacuum value will lower turbine efficiency. Chilled water spraying is adopted to cool down the steam before it is extracted through extraction opening in condenser so as to enhance extraction effect of vacuum pump. This paper gives analysis on chilled water spraying through extraction opening. Mathematic model of selected controlling volume near extraction opening is given. Maximum amount of spraying and its relationship with vacuum value and increment of extraction rate are also proposed.

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Campbell, Duncan C. "Micro-Kjeldahl Analysis Using 40-Tube Block Digestor and Steam Distillation." Journal of AOAC INTERNATIONAL 69, no. 6 (November 1, 1986): 1013–16. http://dx.doi.org/10.1093/jaoac/69.6.1013.

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Abstract A steam distillation unit was developed for use with a 40-tube block digestor (25 x 290 mm tubes). Initial digestion for 10 min with sufficient H2SO4 alone avoids frothing. A K2SO4/HgO mixture is then added and the digestion is continued. Use of condenser tubes and a fan to cool condensers and the tops of digestion tubes allows the use of high block temperatures (450°C) and long digestion times (1.5 h) with little loss of acid. The steam distillation unit incorporates a large head which contains the steam/sample solution mixture during distillation. The large distillation head allows the acid and base solutions to be sufficiently dilute to avoid a violent reaction when mixed. Distillation was 99.9% complete about 2.2 min after distillate appeared in the condenser. To demonstrate the use of the apparatus, rapeseed (Brassica napus cv. Altex) was ground and forty 0.5 g samples were analyzed giving the following results: mean 23.34%, SD 0.07, CV 0.005%, min. 23.17%, max. 23.46%, range 0.29%. Complete digestion and recovery rate were indicated for nicotinic acid by recovery of 99.9-100.0% of the nitrogen.

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He, Wei Feng, and Yi Ping Dai. "Pressure Forecast of an Air-Cooled Steam Condenser under Wind Speeds." Advanced Materials Research 383-390 (November 2011): 6187–93. http://dx.doi.org/10.4028/www.scientific.net/amr.383-390.6187.

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Direct air-cooled power plant is popularized in north China because of the water conservation. Different from the water-cooled condenser, the ambient air absorbs the latent heat that turbine exhaust in the heat exchangers releases. In this paper, the numerical model of a 2×600MW power plant is prepared to simulate the performance of the air–cooled steam condenser under different wind speeds. Heat transferring with phase change is very complicated so that User Define Function(UDF) is applied to calculate the heat transfer rate in the air-cooled condenser. The fan flow rate will drop obviously during the increasing of the wind speed. As a result, the heat transfer rate between the steam and the ambient air also decreases and the pressure of the condenser rises. Finally, the stable condenser pressures under different wind speeds are predicted. The result shows that the air-cooled condenser is very sensitive to the wind speed.

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Journal articles on the topic 'Condensers (Steam) Heat'

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