Journal articles: 'Thermohydraulic parameters'

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Belozerov, Vladimir I., Mikhail M. Zhuk, and Anna M. Terekhova. "Investigation of the small break conditions in the primary circuit of a VVER-1000 reactor*." Nuclear Energy and Technology 5, no. 1 (2019): 47–52. http://dx.doi.org/10.3897/nucet.5.33982.

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Modes with violation of the reactor plant cooling conditions on the primary circuit side of a VVER reactor were simulated using the TRAC-PD2 and Open FOAM thermohydraulic codes (TRAC-PD2 1981, OpenFOAM User Guide Version 1.6. 2009, OpenFOAM Programmer’s Guide Version 1.6. 2009) based on energy and mass conservation equations for the three-dimensional unsteady flow of a two-phase mixture. Coupled simulation of the dynamics of neutronic and thermohydraulic processes (TRAC-PD2 1981, OpenFOAM User Guide Version 1.6. 2009, OpenFOAM Programmer’s Guide Version 1.6. 2009, Bolshagin et al. 2009, Galanin 1971, Weinberg and Wigner 1961, Ovchinnikov and Semenov 1988, Report LA-UR-03-1987) aims to improve the qualitative understanding and the quantitative presentation of their effects on safety. Investigating these modes using the above thermohydraulic codes makes it possible to analyze the course of transients and certain emergency processes without using the industrial testing method, this providing the basis for solving the problems of ensuring the reliability, operational safety and efficiency of nuclear power plants. A modern nuclear reactor is a complex system studying and calculating which requires more than the use of simple theoretical models. Thermohydraulic calculations are an essential part of most engineering and technological development works in nuclear power. Since, in conditions of an NPP, no technologically conventional way can be used to verify and update the results and findings of an a priori analysis on the basis of commercial tests, investigations based on codes are used in some cases as the tools to study and predict the parameters of thermohydraulic processes in the reactor’s circulation circuit. The main purpose of the study is to calculate and investigate, based on codes, modes with violation of the reactor plant cooling conditions on the primary circuit side of a VVER reactor in order to determine if calculated parameters conform to the acceptance criteria established by regulatory documents.

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Sharayevsky, I. G., N. M. Fialko, A. V. Nosovskyi, L. B. Zimin, T. S. Vlasenko, and G. I. Sharayevsky. "Actual problems of the thermal hydraulic reliability ensuring of prospective nuclear reactors with supercritical parameters." Nuclear Power and the Environment 20 (2021): 27–38. http://dx.doi.org/10.31717/2311-8253.21.1.2.

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There is a significant lack of reliable information on the physical characteristics of thermohydraulic processes in emergency heat transfer modes when cooling the surface of fuel rods with light water coolant with supercritical thermodynamic parameters, in particular, on the physics of heat transfer processes and hydromechanics in the critical area. It is shown that in these conditions there is physical uncertainty about the causes of deteriorating heat transfer, which limits the possibility of creating effective calculation techniques for reliable determination of the upper limit of safe forcing of the heat transfer process in the core. At present, the vast majority of theoretical and experimental studies of thermohydraulic processes in the near-critical area have been performed only for the socalled “normal” heat transfer, which corresponds to the heat removal conditions with mixed turbulent convection of superheated to “gas” state of light water coolant in its inertial mode. Attention is paid to the possible appearance of macromolecular ensembles on this surface in the form of pseudo-vapor formations, which are capable of causing an emergency mode of pseudo-film boiling. On the basis of the given experimental data of various authors existence of rather deep physical analogy between processes of heat exchange in supercritical thermodynamic system and unheated boiling at subcritical parameters of the heat carrier is proved. Existence of the pseudo-boiling process in the conditions of supercritical thermodynamic parameters makes it impossible to use in the thermohydraulic calculation the empirical dependences for “hot” gas for the range of active zones operational parameters.

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Diemienkov, V., O. Shugailo, M. Mustafin, and M. Makarenko. "Assessing Structural Integrity of NPP Equipment and Pipelines by Coupled Calculations in ANSYS and RELAP Codes." Nuclear and Radiation Safety, no. 3(87) (September 15, 2020): 46–54. http://dx.doi.org/10.32918/nrs.2020.3(87).06.

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One of the milestones leading to the unit transition to long-term operation is the assessment of the current technical state of equipment and pipelines during the periodic safety review. An integral part of this assessment are the strength calculations within the necessity to take into account rapid thermohydraulic parameters changing during non-stationary transients. Such calculations are characterized by the need for taking into account the relationship between equipment units and pipelines of the reactor coolant system. This task requires additional development of a complex three-dimensional FE model of reactor coolant system. The submodeling approach was used to perform the strength calculation of primary equipment. This approach involves the step-by-step process of strength calculations including the development of a thermohydraulic model with thermohydraulic analysis, the creation of a simplified complex finite element model of the reactor unit containing basic equipment and pipelines, validation, detailed transfer of boundary condition datasets for finite element model and determination of stress strain state for all calculation modes, and performance of the specified calculations of the equipment by a method of submodeling at the end. In general, the implementation of the whole complex of thermohydraulic and strength calculations within one program code is a quite complicated task and requires creating a separate approach. This paper presents the results of developing a comprehensive approach using the coupled calculations in the thermohydraulic and strength codes.

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Huda, M. Q., and S. I. Bhuiyan. "Investigation of thermohydraulic parameters during natural convection cooling of TRIGA reactor." Annals of Nuclear Energy 33, no. 13 (2006): 1079–86. http://dx.doi.org/10.1016/j.anucene.2006.08.001.

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Djordjevic, Emila, Slobodan Serbanovic, Dejan Milosevic, Aleksandar Tasic, and Bojan Djordjevic. "Influence of the outlet air temperature on the thermohydraulic behaviour of air coolers." Chemical Industry 57, no. 4 (2003): 159–64. http://dx.doi.org/10.2298/hemind0304159d.

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The determination of the optimal process conditions for the operation of air coolers demands a detailed analysis of their thermohydraulic behaviour on the one hand, and the estimation of the operating costs, on the other. One of the main parameters of the thermohydraulic behaviour of this type of equipment, is the outlet air temperature. The influence of the outlet air temperature on the performance of air coolers (heat transfer coefficient overall heat transfer coefficient, required surface area for heat transfer air-side pressure drop, fan power consumption and sound pressure level) was investigated in this study. All the computations, using AirCooler software [1], were applied to cooling of the process fluid and the condensation of a multicomponent vapour mixture on two industrial devices of known geometries.

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Radhakrishna, H. S., A. M. Crawford, B. Kjartanson, and K. C. Lau. "Numerical modelling of heat and moisture transport through bentonite–sand buffer." Canadian Geotechnical Journal 29, no. 6 (1992): 1044–59. http://dx.doi.org/10.1139/t92-122.

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A computer code TRUCHAM developed to model the coupled heat and moisture flow through a porous medium is used to assess the thermohydraulic performance of the clay-based engineered barrier encapsulating nuclear waste containers in a deep geological disposal vault in the borehole emplacement concept. This paper contains an overview of the development of the numerical model and its application to the buffer–container experiment at the Underground Research Laboratory of Atomic Energy of Canada Limited Research. The thermohydraulic transport parameters required for the analysis were determined by specially designed laboratory experiments. The needs for further development of the model and the material properties are identified. Key words : buffer, clay barrier, coupled heat and moisture, heater experiment, numerical model, nuclear waste disposal, thermal diffusivity, unsaturated soil.

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Chai, Lei, and Savvas Tassou. "A Review of Airside Heat Transfer Augmentation with Vortex Generators on Heat Transfer Surface." Energies 11, no. 10 (2018): 2737. http://dx.doi.org/10.3390/en11102737.

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Heat exchanger performance can be improved via the introduction of vortex generators to the airside surface, based on the mechanism that the generated longitudinal vortices can disrupt the boundary layer growth, increase the turbulence intensity and produce secondary fluid flows over the heat transfer surfaces. The key objective of this paper is to provide a critical overview of published works relevant to such heat transfer surfaces. Different types of vortex generator are presented, and key experimental techniques and numerical methodologies are summarized. Flow phenomena associated with vortex generators embedded, attached, punched or mounted on heat transfer surfaces are investigated, and the thermohydraulic performance (heat transfer and pressure drop) of four different heat exchangers (flat plate, finned circular-tube, finned flat-tube and finned oval-tube) with various vortex-generator geometries, is discussed for different operating conditions. Furthermore, the thermohydraulic performance of heat transfer surfaces with recently proposed vortex generators is outlined and suggestions on using vortex generators for airside heat transfer augmentation are presented. In general, the airside heat transfer surface performance can be substantially enhanced by vortex generators, but their impact can also be significantly influenced by many parameters, such as Reynolds number, tube geometry (shape, diameter, pitch, inline/staggered configuration), fin type (plane/wavy/composite, with or without punched holes), and vortex-generator geometry (shape, length, height, pitch, attack angle, aspect ratio, and configuration). The finned flat-tube and finned oval-tube heat exchangers with recently proposed vortex generators usually show better thermohydraulic performance than finned circular tube heat exchangers. Current heat exchanger optimization approaches are usually based on the thermohydraulic performance alone. However, to ensure quick returns on investment, heat exchangers with complex geometries and surface vortex generators, should be optimized using cost-based objective functions that consider the thermohydraulic performance alongside capital cost, running cost of the system as well as safety and compliance with relevant international standards for different applications.

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De Jaeger, Peter, Christophe T’Joen, Henk Huisseune, Bernd Ameel, Sven De Schampheleire, and Michel De Paepe. "Influence of Geometrical Parameters of Open-Cell Aluminum Foam on Thermohydraulic Performance." Heat Transfer Engineering 34, no. 14 (2013): 1202–15. http://dx.doi.org/10.1080/01457632.2013.776899.

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Wehling, H. J., K. Klingler, and H. Stölben. "The influence of thermohydraulic parameters on the dynamic behaviour of KWU-PWR's." Progress in Nuclear Energy 15 (January 1985): 273–82. http://dx.doi.org/10.1016/0149-1970(85)90050-2.

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Sharaevsky, І. G., N. М. Fіаlkо, А. V. Nоsоvskyi, L. B. Zimin, Т. S. Vlasenko, and G. І. Sharaevsky. "Problem issues of cores thermal-hydraulic calculation for prospective water-cooled reactors with supercritical parameters." Nuclear Power and the Environment 19, no. 4 (2020): 3–15. http://dx.doi.org/10.31717/2311-8253.20.4.1.

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The fundamental thermophysical features of the heat exchange process between the heated wall of a vertical channel and the light-water coolant of supercritical parameters concerning the conditions of heat-generating assemblies channels and cores of perspective energy nuclear reactors are considered. The available methods and recommendations for determining the limits of thermal load are analyzed. It is a guarantee the absence of the characteristic dangerous mode possibility of deteriorated heat exchange in these conditions and corresponding sharp rise in the channels wall temperature, which threatens their destruction. The physical nature of the occurrence of degraded heat transfer regimes remains unclear, and the existing approaches to the implementation of thermohydraulic calculation in such conditions are not sufficiently justified. The complex nature of intercellular heat and mass transfer in the fuel assembly and the presence of individual thermohydraulic cells with reduced levels of heat transfer intensity indicate that the existing method of determining the area of degraded heat transfer in the reactor core channels with supercritical parameters of the coolant is significantly simplified. Insufficient data and research results have been revealed to create adequate methods of heat-hydraulic calculation, suitable for taking into account the peculiarities of the heat transfer process complex flow under conditions of supercritical parameters of the coolant. The application of such methods should be the basis for ensuring the safe operation of prospective reactors and minimizing potential losses of a different nature from accidents caused by the destruction of cores through unacceptable heat transfer modes. To this end, the main direction of further research is identified.

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Zakirov, S. Yu. "Calculation of the thermohydraulic parameters of a core comprised of unjacketed fuel assemblies." Atomic Energy 107, no. 6 (2009): 374–80. http://dx.doi.org/10.1007/s10512-010-9239-6.

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12

Liu, X. P., and J. L. Niu. "Effects of geometrical parameters on the thermohydraulic characteristics of periodic cross-corrugated channels." International Journal of Heat and Mass Transfer 84 (May 2015): 542–49. http://dx.doi.org/10.1016/j.ijheatmasstransfer.2015.01.046.

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13

Alam, Tabish, R. P. Saini, and J. S. Saini. "Experimental Investigation of Thermohydraulic Performance of a Rectangular Solar Air Heater Duct Equipped with V-Shaped Perforated Blocks." Advances in Mechanical Engineering 6 (January 1, 2014): 948313. http://dx.doi.org/10.1155/2014/948313.

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This paper presents the thermohydraulic performance of rectangular solar air heater duct equipped with V-shaped rectangular perforated blocks attached to the heated surface. The V-shaped perforated blocks are tested for downstream (V-down) to the air flow at Reynolds number from 2000 to 20000. The perforated blocks have relative pitch ratio ( P/e) from 4 to 12, relative blockage height ratio ( e/H) from 0.4 to 1.0, and open area ration from 5% to 25% at a fixed value of angle of attack of 60∘ in a rectangular duct having duct aspect ratio ( W/H) of 12. Thermohydraulic performance is compared at different geometrical parameters of V-shaped perforated blocks for equal pumping power which shows that maximum performance is observed at a relative pitch of 8, relative rib height of 0.8, and open area ration of 20%. It is also observed that the performance of V-shaped perforated blocks was better than transverse-perforated blocks.

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Litvintsova, Y. E., S. Laouar, M. I. Delov, D. M. Kuzmenkov, A. A. Lavrukhin, and K. V. Kutsenko. "Diagnostics of coolant boiling onset based on the analysis of fluctuations of thermohydraulic parameters." Journal of Physics: Conference Series 1689 (November 2020): 012042. http://dx.doi.org/10.1088/1742-6596/1689/1/012042.

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Kroshilin, A. E., and V. N. Maidanik. "A new approach to calculating parameters of thermohydraulic networks for vapor-gas-liquid flows." Thermal Engineering 54, no. 5 (2007): 368–74. http://dx.doi.org/10.1134/s0040601507050060.

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SUBKI, Muhammad Hadid, Masanori ARITOMI, Noriyuki WATANABE, Moon Ki CHUNG, and Hiroshige KIKURA. "Multi Parameters Effect on Thermohydraulic Instability in Natural Circulation Boiling Water Reactor during Startup." JSME International Journal Series B 47, no. 2 (2004): 277–86. http://dx.doi.org/10.1299/jsmeb.47.277.

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Karwa, Rajendra, and Shweta Baghel. "Effect of Parametric Uncertainties, Variations, and Tolerances on Thermohydraulic Performance of Flat Plate Solar Air Heater." Journal of Solar Energy 2014 (September 21, 2014): 1–18. http://dx.doi.org/10.1155/2014/194764.

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The paper presents results of an analysis carried out using a mathematical model to find the effect of the uncertainties, variations, and tolerances in design and ambient parameters on the thermohydraulic performance of flat plate solar air heater. Analysis shows that, for the range of flow rates considered, a duct height of 10 mm is preferred from the thermohydraulic consideration. The thermal efficiency changes by about 2.6% on variation in the wind heat transfer coefficient, ±5 K variation in sky temperature affects the efficiency by about ±1.3%, and solar insolation variation from 500 to 1000 Wm−2 affects the efficiency by about −1.5 to 1.3% at the lowest flow rate of 0.01 kgs−1 m−2 of the absorber plate with black paint. In general, these effects reduce with increase in flow rate and are lower for collector with selective coating on the absorber plate surface. The tolerances in the duct height and absorber plate emissivity should be small while positive tolerance of 3° in the collector slope for winter operation and ±3° for year round operation, and a positive tolerance for the gap between the absorber plate and glass cover at nominal value of 40 mm are recommended.

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Yadav, Anil Singh, and J. L. Bhagoria. "Modeling and Simulation of Turbulent Flows through a Solar Air Heater Having Square-Sectioned Transverse Rib Roughness on the Absorber Plate." Scientific World Journal 2013 (2013): 1–12. http://dx.doi.org/10.1155/2013/827131.

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Solar air heater is a type of heat exchanger which transforms solar radiation into heat energy. The thermal performance of conventional solar air heater has been found to be poor because of the low convective heat transfer coefficient from the absorber plate to the air. Use of artificial roughness on a surface is an effective technique to enhance the rate of heat transfer. A CFD-based investigation of turbulent flow through a solar air heater roughened with square-sectioned transverse rib roughness has been performed. Three different values of rib-pitch (P) and rib-height (e) have been taken such that the relative roughness pitch (P/e=14.29) remains constant. The relative roughness height,e/D, varies from 0.021 to 0.06, and the Reynolds number, Re, varies from 3800 to 18,000. The results predicted by CFD show that the average heat transfer, average flow friction, and thermohydraulic performance parameter are strongly dependent on the relative roughness height. A maximum value of thermohydraulic performance parameter has been found to be 1.8 for the range of parameters investigated. Comparisons with previously published work have been performed and found to be in excellent agreement.

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Zeigarnik, Yu A., and F. P. Ivanov. "Determination of the characteristic linear dimension for calculating the thermohydraulic parameters of a porous structure." High Temperature 51, no. 1 (2013): 135–37. http://dx.doi.org/10.1134/s0018151x13010215.

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Katona, Tamás, and Robert Kozma. "Problems of estimation of the thermohydraulic parameters using neutron and temperature noise signals in PWRs." Progress in Nuclear Energy 21 (January 1988): 431–45. http://dx.doi.org/10.1016/0149-1970(88)90061-3.

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Yanovskiy, S., O. Zhabin, and V. Pustovit. "Validation of WWER-440/213 Thermohydraulic Model for TRACE Computer Code Based on RNPP-1 Incident Data." Nuclear and Radiation Safety, no. 4(84) (December 19, 2019): 34–45. http://dx.doi.org/10.32918/nrs.2019.4(84).05.

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This paper describes the main steps and results of preparing WWER-440/213 model for TRACE system thermohydraulic code to be used in further deterministic analysis calculations. As the basis for developing the model, the previously developed RELAP5/Mod.3.2 input deck was used. As a first step, the thermohydraulic components of input deck were automatically converted to TRACE format using SNAP utility. Then, necessary manual adjustments and additions were implemented to incorporate the safeguards actuation logic and operation of various plant controllers into the model. A set of validation calculations was performed for various transients (abnormal operation events) that had actually occurred at Rivne NPP Unit 1 to confirm that the TRACE model is capable of reproducing adequately the response of nuclear power plant with WWER-440/213 reactor. The results for one of validation calculations (Loss of normal power supply with reactor scram and additional failures) are provided as an example. Comparison of calculation results with plant measured data demonstrate acceptable agreement for the main plant parameters. To extend the scope of model validation, the cross-code comparison between TRACE and RELAP5 results is planned to be performed for a number of representative design-basis accident scenarios.

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Bahiraei, Mehdi, Khashayar Gharagozloo, and Hossein Moayedi. "Experimental study on effect of employing twisted conical strip inserts on thermohydraulic performance considering geometrical parameters." International Journal of Thermal Sciences 149 (March 2020): 106178. http://dx.doi.org/10.1016/j.ijthermalsci.2019.106178.

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SUBKI, Muhammad Hadid, Noriyuki WATANABE, Masanori ARITOMI, Moon Ki CHUNG, and Hiroshige KIKURA. "ICONE11-36077 MULTI PARAMETERS EFFECT ON THERMOHYDRAULIC INSTABILITY IN NATURAL CIRCULATION BOILING WATER REACTOR DURING STARTUP." Proceedings of the International Conference on Nuclear Engineering (ICONE) 2003 (2003): 230. http://dx.doi.org/10.1299/jsmeicone.2003.230.

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Alfaryjat, A. A., H. A. Mohammed, Nor Mariah Adam, M. K. A. Ariffin, and M. I. Najafabadi. "Influence of geometrical parameters of hexagonal, circular, and rhombus microchannel heat sinks on the thermohydraulic characteristics." International Communications in Heat and Mass Transfer 52 (March 2014): 121–31. http://dx.doi.org/10.1016/j.icheatmasstransfer.2014.01.015.

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Xu, Zhe, Yingqing Guo, Haotian Mao, and Fuqiang Yang. "Configuration Optimization and Performance Comparison of STHX-DDB and STHX-SB by A Multi-Objective Genetic Algorithm." Energies 12, no. 9 (2019): 1794. http://dx.doi.org/10.3390/en12091794.

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Based on the thermohydraulic calculation model verified in this study and Non-dominated Sorted Genetic Algorithm-II (NSGA-II), a multi-objective configuration optimization method is proposed, and the performances of shell-and-tube heat exchanger with disc-and-doughnut baffles (STHX-DDB) and shell-and-tube heat exchanger with segmental baffles (STHX-SB) are compared after optimization. The results show that, except in the high range of heat transfer capacity of 16.5–17 kW, the thermohydraulic performance of STHX-DDB is better. Tube bundle diameter, inside tube bundle diameter, number of baffles of STHX-DDB and tube bundle diameter, baffle cut, number of baffles of STHX-SB are chosen as design parameters, and heat transfer capacity maximization and shell-side pressure drop minimization are considered as common optimization objectives. Three optimal configurations are obtained for STHX-DDB and another three are obtained for STHX-SB. The optimal results show that all the six selected optimal configurations are better than the original configurations. For STHX-DDB and STHX-SB, compared with the original configurations, the heat transfer capacity of optimal configurations increases by 6.26% on average and 5.16%, respectively, while the shell-side pressure drop decreases by 44.33% and 19.16% on average, respectively. It indicates that the optimization method is valid and feasible and can provide a significant reference for shell-and-tube heat exchanger design.

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Abbasian Arani, Ali Akbar, and Hamed Uosofvand. "Improving shell and tube heat exchanger thermohydraulic performance using combined baffle." International Journal of Numerical Methods for Heat & Fluid Flow 30, no. 8 (2019): 4119–40. http://dx.doi.org/10.1108/hff-06-2019-0514.

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Purpose This paper aims to investigate the fluid flow and heat transfer of a laboratory shell and tube heat exchanger that are analyzed using computational fluid dynamic approach by SOLIDWORKS flow simulation (ver. 2015) software. Design/methodology/approach In this study, several types of baffle including segmental baffle, butterfly baffle, helical baffle, combined helical-segmental baffle, combined helical-disk baffle and combined helical-butterfly baffle are examined. Two important parameters as the heat transfer and pressure drop are evaluated and analyzed. Based on obtained results, segmental baffle has the highest amount of heat transfer and pressure drop. To assess the integrative performance, performance coefficient defines as “Q/Δp” is used. Findings This investigation showed that among the presented baffle types, the heat exchangers equipped with disk baffle has the highest heat transfer. In addition, in the same mass flow rate, the performance coefficient of the shell and tube heat exchanger equipped with helical-butterfly baffle is the highest among the proposed models. Originality/value After combined helical-butterfly baffle the butterfly baffle, disk baffle, helical-segmental baffle and helical-disk baffle show their superiority of 35.12, 25, 22 and 12 per cent rather than the common segmental baffle, respectively. Furthermore, except for the combined helical-disk baffle, the other type of combined baffle have better performance compare to the basic configuration (butterfly and segmental baffle).

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Amanuel, Tarikayehu, and Manish Mishra. "Thermohydraulic optimization of triple concentric-tube heat exchanger: A multi-objective approach." Proceedings of the Institution of Mechanical Engineers, Part E: Journal of Process Mechanical Engineering 233, no. 3 (2018): 589–600. http://dx.doi.org/10.1177/0954408918779232.

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In the present study, optimization of heat transfer and pressure drop characteristics in a triple concentric tube heat exchanger has been done using the results of numerical simulation. A commercial CFD software ANSYS Fluent v17.0 has been employed for simulating the flow and heat transfer, while optimization has been done by Response surface methodology (RSM) and Genetic algorithm (GA). The effective parameters in the study are Reynolds number (2500 ≤ Re ≤ 10,000) and Length to hydraulic diameter ratio (100 ≤ L/Dh ≤ 220). The optimum values, as well as the functional relationship between the design factors (Re and L/Dh) and response variables (Nu and f), have also been developed. It has been found that both the design factors (Re and L/Dh) have a strong influence on the response variables (Nu and f). With the increase in Re (flow rate), a large growth in Nusselt number and decline in friction factor has been observed. However, with the increase in L/Dh, an enormous decrease in both Nusselt number and friction factor has been found.

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Muniak, Damian Piotr. "The Impact of the Use of Antifreeze Substances on the Heating Installation Thermohydraulic Parameters and Energy Consumption." Heat Transfer Engineering 42, no. 3-4 (2019): 347–53. http://dx.doi.org/10.1080/01457632.2019.1699305.

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Nguyen, Kien-Cuong, Vinh-Vinh Le, Ton-Nghiem Huynh, Ba-Vien Luong, and Nhi-Dien Nguyen. "Steady-State Thermal-Hydraulic Analysis of the LEU-Fueled Dalat Nuclear Research Reactor." Science and Technology of Nuclear Installations 2021 (February 27, 2021): 1–10. http://dx.doi.org/10.1155/2021/6673162.

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This paper presents results of steady-state thermal-hydraulic analysis for the designed working core of the Dalat Nuclear Research Reactor (DNRR) using the PLTEMP/ANL code. The core was designed to be loaded with 92 low-enriched uranium (LEU) VVR-M2 fuel bundles (FBs) and 12 beryllium rods surrounding a neutron trap at the core center, for replacement of the previous core with 104 high-enriched uranium (HEU) VVR-M2 FBs. Before using this code for thermohydraulic analysis of the designed LEU working core, it was validated by comparing calculation results with experimental data collected from the HEU working core of the DNRR. The discrepancy between calculated results and measured data was at the maximum about 0.8°C and 1.5°C of fuel cladding and outlet coolant temperatures, respectively. In the design calculation, thermohydraulic safety was confirmed through evaluation of the fuel cladding and coolant temperatures, as well as of other safety parameters such as Departure from Nucleate Boiling Ratio (DNBR) and Onset of Nucleate Boiling Ratio (ONBR). The calculation results showed that, in normal operation conditions at full nominal thermal power of 500 kW without uncertainty parameters, the maximum fuel cladding temperature of the hottest FB was about 90.4°C, which is lower than its limit value of 103°C, the minimum DNBR was 32.0, which is much higher than the recommended value of 1.5, and the minimum ONBR was 1.43, which is higher than the recommended value of 1.4 for VVR-M2 LEU fuel type. When the global and local hot channel factors were taken into account, the maximum temperature of fuel cladding at the hottest FB was about 98.4 °C, for global only, and 114.3°C, for global together with local hot channel factors. The calculation results confirm the safety operation of the designed LEU core loaded with 92 fresh VVR-M2 FBs.

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Li, Cong, Hong-Ju Guo, Wei-Biao Ye, Yuxiang Hong, and Si-Min Huang. "THERMOHYDRAULIC CHARACTERISTICS OF MICROCHANNEL HEAT SINKS COMBINED WITH RIBS AND CAVITIES: EFFECTS OF GEOMETRIC PARAMETERS AND HEAT FLUX." Heat Transfer Research 50, no. 1 (2019): 89–105. http://dx.doi.org/10.1615/heattransres.2018026458.

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Garusov, E. A. "Determination of the Thermohydraulic Parameters of Inter-Fuel-Element Channels in Research Reactors with Four-Bladed Fuel Elements." Atomic Energy 119, no. 6 (2016): 384–90. http://dx.doi.org/10.1007/s10512-016-0078-y.

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Zakharenkov, Aleksandr V., Ivan A. Tupotilov, and Kirill V. Zhuravlev. "An Experimental Study of Thermohydraulic Processes in the Model of a Fuel Assembly with Micro Fuel Elements." Vestnik MEI 3, no. 3 (2021): 19–25. http://dx.doi.org/10.24160/1993-6982-2021-3-19-25.

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The test section design of the TVS-MEI experimental setup intended for studying the hydrodynamics and heat transfer in a fuel assembly with micro fuel elements is developed, and the setup hydraulic circuit is modernized. The setup process characteristics correspond to the operational parameters of VVER-1000 reactor plants (a pressure up to 16 MPa and coolant temperature up to 350°C). The internal heat release in the bed of metal pebbles is obtained by high-frequency induction heating. A technology for compacting the test section made of high-strength alundum ceramics and a special clamping device for holding the bed were developed. The fuel assemblies with micro fuel elements have the outer geometrical parameters fully identical with those of the conventional assemblies with fuel rods. A technology for installing, wiring, and sealing thermocouples in the test section has been developed. Experimental studies aimed at determining the pressure loss and flow friction coefficient for a cylindrical pebble bed were carried with the following coolant operating parameters: P = (2--7) MPa and G = (0.05--0.5) kg/s. In processing the obtained experimental results, the dependences of pressure loss on the coolant mass velocity and the pebble bed flow friction on the Reynolds number were identified and plotted. The first experimental data on the temperature distribution in the pebble bed are obtained. The main objective of the experiments was to determine the possibility of heating the considered test section by using the chosen method.

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Smorchkova, Yu V., E. A. Avdonina, and A. V. Dedov. "INVESTIGATION OF THERMOHYDRAULIC AND NEUTRON -PHYSICAL CHARACTERISTICS OF PERSPECTIVE FUEL ASSEMBLY FOR LOW-POWER REACTOR FACILITY." Proceedings of the higher educational institutions. ENERGY SECTOR PROBLEMS 20, no. 7-8 (2018): 23–34. http://dx.doi.org/10.30724/1998-9903-2018-20-7-8-23-34.

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The paper presents the results of a numerical study of hydrodynamics and a temperature field in the model of the fuel assembly for the KLT-40S reactor installation in the transition to a fuel consisting of spherical microfuels. The optimal design of a model of a f uel assembly with microfuels for a reactor installation KLT-40S is proposed, from the position of hydrodynamics and heat transfer. The fuel assembly by external dimensions completely corresponds to the traditional assembly with rod fuel elements. The optim al parameters of the perforation of the covers that retain the pebble bed of microfuels are determined. The results of the evaluation of neutron-physical characteristics are presented. The working capacity of the KLT-40S reactor installation is shown when using fuel from microfuel elements.

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Bhattacharyya, Suvanjan, Debraj Sarkar, Ulavathi Shettar Mahabaleshwar, Manoj K. Soni, and M. Mohanraj. "Experimental study of thermohydraulic characteristics and irreversibility analysis of novel axial corrugated tube with spring tape inserts." European Physical Journal Applied Physics 92, no. 3 (2020): 30901. http://dx.doi.org/10.1051/epjap/2020200192.

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The current study experimentally investigates the heat transfer augmentation on the novel axial corrugated heat exchanger tube in which the spring tape is introduced. Air (Pr = 0.707) is used as a working fluid. In order to augment the thermohydraulic performance, a corrugated tube with inserts is offered. The experimental study is further extended by varying the important parameters like spring ratio (y = 1.5, 2.0, 2.5) and Reynolds number (Re = 10 000–52 000). The angular pitch between the two neighboring corrugations and the angle of the corrugation is kept constant through the experiments at β = 1200 and α = 600 respectively, while two different corrugations heights (h) are analyzed. While increasing the corrugation height and decreasing the spring ratio, the impact of the swirling effect improves the thermal performance of the system. The maximum thermal performance is obtained when the corrugation height is h = 0.2 and spring ratio y = 1.5. Eventually, correlations for predicting friction factor (f) and Nusselt number (Nu) are developed.

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Zajtsev, Aleksey, Vyacheslav Dorovskikh, Sergey Dorokhovich, Valery Levchenko, and Igor Leonov. "The SIMCO containment code applied to modeling hydrogen distribution in containments of nuclear power facilities." Nuclear Energy and Technology 4, no. 4 (2018): 279–85. http://dx.doi.org/10.3897/nucet.4.31892.

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The article gives a general description of the SIMCO calculation code designed to simulate thermohydraulic and physico-chemical processes in containments of nuclear power facilities. The authors present a calculation technique based on a physico-mathematical model in lumped parameters. As a numerical solution method, the modified semi-implicit SIMPLER procedure is used. The code was examined using analytical and qualitative tests. A comparison of the numerical and analytical solutions showed good agreement. The code was verified using the experimental data obtained at the NUPEC installation (Japan). Based on the results of testing and verification, it was concluded that, in general, physico-mathematical code models adequately describe the processes of heat/mass transfer in the containment. Therefore, this SIMCO code version can be used to analyze the totality of thermophysical and physico-chemical processes in nuclear power facilities with containments, including the transfer of hydrogen/steam/air mixtures.

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Chai, Lei, Konstantinos M. Tsamos, and Savvas A. Tassou. "Modelling and Evaluation of the Thermohydraulic Performance of Finned-Tube Supercritical Carbon Dioxide Gas Coolers." Energies 13, no. 5 (2020): 1031. http://dx.doi.org/10.3390/en13051031.

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This paper investigates the thermohydraulic performance of finned-tube supercritical carbon dioxide (sCO2) gas coolers operating with refrigerant pressures near the critical point. A distributed modelling approach combined with the ε-NTU method has been developed for the simulation of the gas cooler. The heat transfer and pressure drop for each evenly divided segment are calculated using empirical correlations for Nusselt number and friction factor. The model was validated against test results and then used to investigate the influence of design and operating parameters on local and overall gas cooler performance. The results show that the refrigerant heat-transfer coefficient increases with decreasing temperature and reaches its maximum close to the pseudocritical temperature before beginning to decrease. The pressure drop increases along the flow direction with decreasing temperature. Overall performance results illustrate that higher refrigerant mass flow rate and decreasing finned-tube diameter lead to improved heat-transfer rates but also increased pressure drops. Design optimization of gas coolers should take into consideration their impact on overall refrigeration performance and life cycle cost. This is important in the drive to reduce the footprint of components, energy consumption, and environmental impacts of refrigeration and heat-pump systems. The present work provides practical guidance to the design of finned-tube gas coolers and can be used as the basis for the modelling of integrated sCO2 refrigeration and heat-pump systems.

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Thao, Pham Ba, Duong Cong Truyen, and Nguyen Minh Phu. "CFD Analysis and Taguchi-Based Optimization of the Thermohydraulic Performance of a Solar Air Heater Duct Baffled on a Back Plate." Applied Sciences 11, no. 10 (2021): 4645. http://dx.doi.org/10.3390/app11104645.

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In this paper, a solar air collector duct equipped with baffles on a back plate was numerically investigated. The Reynolds number (Re) was varied from 5000 to 20,000, the angle baffle (a) from 30° to 120°, the baffle spacing ratio (Pr) from 2 to 8, and the baffle blockage ratio (Br) from 0.375 to 0.75 to examine their effects on the Nusselt number (Nu), the friction factor (f), and the thermohydraulic performance parameter (η). The 2D numerical simulation used the standard k-ε turbulence model with enhanced wall treatment. The Taguchi method was used to design the experiment, generating an orthogonal array consisting of four factors each at four levels. The optimization results from the Taguchi method and CFD analysis showed that the optimal geometry of a = 90°, Pr = 6, and Br = 0.375 achieved the maximum η. The influence of Br on all investigated parameters was considerable because as Br increased, a larger primary vortex region was formed downstream of the baffle. At Re = 5000 and the optimal geometry parameters, a maximum η of 1.01 was reached. A baffle angle between 60° and 90° achieved a high Nusselt number due to the impingement heat transfer.

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Jaeger, Wadim, Victor Hugo Sánchez Espinoza, Francisco Javier Montero Mayorga, and Cesar Queral. "Uncertainty and Sensitivity Studies with TRACE-SUSA and TRACE-DAKOTA by Means of Transient BFBT Data." Science and Technology of Nuclear Installations 2013 (2013): 1–9. http://dx.doi.org/10.1155/2013/565246.

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In the present paper, an uncertainty and sensitivity study is performed for transient void fraction and pressure drop measurements. Two transients have been selected from the NUPEC BFBT database. The first one is a turbine trip without bypass and the second one is a trip of a recirculation pump. TRACE (version 5.0 patch 2) is used for the thermohydraulic study and SUSA and DAKOTA are used for the quantification of the model uncertainties and the evaluation of the sensitivities. As uncertain parameters geometrical values, hydraulic diameter, and wall roughness are considered while mass flow rate, power, pressure, and inlet subcooling (inlet temperature) are chosen as boundary and input conditions. Since these parameters change with time, it is expected that the importance of them on pressure drop and void fraction will change, too. The results show that the pressure drop is mostly sensitive to geometrical variations like the hydraulic diameter and the form loss coefficient of the spacer grid. For low void fractions, the parameter of the highest importance is the inlet temperature/subcooling while at higher void fraction the power is also of importance.

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Zubkov, N. N., and Yu L. Bityutskaya. "Simulation of the Deformational Cutting and the Geometric Parameters of Pin Structures to Analyze the Thermohydraulic Characteristics of Heat-Removal Plates." Russian Metallurgy (Metally) 2018, no. 13 (2018): 1202–7. http://dx.doi.org/10.1134/s003602951813027x.

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Pyrohov, T. V., and A. V. Korolev. "Analysis of the thermal stress state of the flange connections elements of the emergency cooling heat exchangers during accidents of the WWER-1000 nuclear installation." Nuclear Power and the Environment 19, no. 4 (2020): 23–30. http://dx.doi.org/10.31717/2311-8253.20.4.3.

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During the assessment of the static strength of the flange connections elements Dn2130 and Dn2080 of the emergency cooling heat exchangers 08.8111.335 SB (TOAR), it was found that there is an excess of the allowable stress values. These calculations of static strength performed using the finite element method (FEM). The analysis of the static strength of the flange joints was performed taking into account the design values of the tightening of the studs, equal to 22,527 kgf and 8,836 kgf, accordingly. At the same time, one of the main purposes of heat exchangers TOAR nuclear installation (NI) WWER-1000 is the work until accidents. The analysis of accidents of NI WWER-1000 showed that the largest values of change of parameters of environments in heat exchangers of TOAR correspond to accident “LOCA: Bilateral rupture of MCT”. Based on this, we considered the thermal stress state of heat exchangers for this accident. To determine the thermal stress state of the TOAR heat exchanger elements, during accidents of the nuclear installation, strength calculations were performed in the non-stationary formulation of the problem. One of the boundary conditions for these strength calculations is the distribution of temperatures along the thickness and length of the walls of the elements of the heat exchanger, which changes over time. Numerical thermohydraulic calculations were performed to determine these boundary conditions. In the article for the first time the results of calculations of thermal stress state of separate elements of heat exchangers TOAR, for work of heat exchangers during accidents of nuclear installation are received. It is established that the elements of the flange connection Dn2130 are one of the most critical elements of TOAR heat exchangers. To determine the thermal stress state of the heat exchanger elements, analytical thermal calculations, numerical thermohydraulic and strength calculations were performed using the FEM method. As a result of the analysis of the performed strength calculations, it was concluded that it is necessary to reduce the tightening value of the flanges of the flange connection Dn2130 to 14600 kgf.

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Bhattacharyya, Suvanjan, Debraj Sarkar, Rahul Roy, Shramona Chakraborty, Varun Goel, and Eydhah Almatrafi. "Application of New Artificial Neural Network to Predict Heat Transfer and Thermal Performance of a Solar Air-Heater Tube." Sustainability 13, no. 13 (2021): 7477. http://dx.doi.org/10.3390/su13137477.

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In the present study, the heat transfer and thermal performance of a helical corrugation with perforated circular disc solar air-heater tubes are predicted using a machine learning regression technique. This paper describes a statistical analysis of heat transfer by developing an artificial neural network-based machine learning model. The effects of variation in the corrugation angle (θ), perforation ratio (k), corrugation pitch ratio (y), perforated disc pitch ratio (s), and Reynolds number have been analyzed. An artificial neural network model is used for regression analysis to predict the heat transfer in terms of Nusselt number and thermohydraulic efficiency, and the results showed high prediction accuracies. The artificial neural network model is robust and precise, and can be used by thermal system design engineers for predicting output variables. Two different models are trained based on the features of experimental data, which provide an estimation of experimental output based on user-defined input parameters. The models are evaluated to have an accuracy of 97.00% on unknown test data. These models will help the researchers working in heat transfer enhancement-based experiments to understand and predict the output. As a result, the time and cost of the experiments will reduce.

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Costa, R. C. S. M., and M. F. Curi. "IMPACT OF NANOFLUIDS ON EXTERNAL AND INTERNAL FLOW VIA NAVIER-STOKES AND CONVECTIONDIFFUSION EQUATIONS FOR PARALLEL PLATES WITH SLIP BOUNDARY CONDITIONS." Revista de Engenharia Térmica 20, no. 1 (2021): 45. http://dx.doi.org/10.5380/reterm.v20i1.80446.

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With the modernization and miniaturization of equipment and systems toincrease the overall efficiency in smaller spaces, new cooling solutions needto be developed. Microfluidic in the last decades becomes a new way to getthis. Nanofluids are used to attend this demand to optimize efficiency, withtheir improved thermohydraulic properties, especially different thermalconductivities. To determine the advantages of using a nanofluid for thermalexchange, the properties, parameters and modelling will be presented, and thedifferential equations necessary to obtain the results. In that sense, the basictheory of fluid mechanics and heat transfer, through the Navier-Stokes andConvection-Diffusion equation, is used in the two-dimensional steady-stateformulation. Slip boundary conditions for the velocity field. Constant heat fluxand constant temperature at the surface are used for the temperature field,initially without the flow’s microscale effects. The external flow over a flatplate and internal flow between parallel plates will be studied. Considering alaminar flow, with the base fluid being water and engine oil, with variousvolumetric fractions of Single Wall and Multiple Wall Carbon Nanotubes. Todetermine the results and create the comparative graphs, the WolframMathematica v.11 software will be used for solving the remaining partialdifferential equations.

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Al-Obaidi, Ahmed Ramadhan, and Jassim Alhamid. "Investigation of flow pattern, thermohydraulic performance and heat transfer improvement in 3D corrugated circular pipe under varying structure configuration parameters with development different correlations." International Communications in Heat and Mass Transfer 126 (July 2021): 105394. http://dx.doi.org/10.1016/j.icheatmasstransfer.2021.105394.

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Kishore, P. S., V. Koteswara Reddy, M. Prem Dheeraj, and K. Pavan Kumar. "STUDY AND OPTIMIZATION OF PARAMETERS THAT INFLUENCE THERMOHYDRAULIC PERFORMANCE OF FLOW IN A DUCT WITH TWISTED TAPE INSERT IN CONJUNCTION WITH DIMPLES OVER ITS SURFACE." Journal of Enhanced Heat Transfer 23, no. 6 (2016): 499–512. http://dx.doi.org/10.1615/jenhheattransf.2018018871.

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Beznosov, A. V., D. V. Davydov, A. G. Meluzov, P. I. Lyakhova, and A. D. Efanov. "Experimental Investigations of the Thermohydraulic Parameters of the Flow Section of a Liquid-Metal Target with a Window for a Proton Beam from an Accelerator." Atomic Energy 95, no. 4 (2003): 667–73. http://dx.doi.org/10.1023/b:aten.0000010983.86428.d2.

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Kotsuba, O., Yu Vorobyov, O. Zhabin, and D. Gumenyuk. "Comparative Analysis of Severe Accident at WWER-1000 NPP with MELCOR 1.8.5 and 2.1 Code Versions." Nuclear and Radiation Safety, no. 1(85) (March 13, 2020): 30–40. http://dx.doi.org/10.32918/nrs.2020.1(85).03.

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An overview of the main improvements in updated version 2.1 of MELCOR computer code related to more representative mathematical modeling of complex thermohydraulic severe accident processes of core degradation, transfer of molten fragments to the bottom of the reactor, heating and failure of the bottom of the reactor pressure vessel is presented. The elements of WWER-1000 NPP computer model for the MELCOR 1.8.5 (control volumes, thermal structures and structures of the reactor core) that are reproduced for a reactor with the primary side, the secondary side and the containment are described. The changes implemented in WWER-1000 NPP model for MELCOR 1.8.5 to convert it to MELCOR 2.1 version that are mainly related to more detailed modeling of the reactor core and reactor pressure vessel bottom are provided. The paper presents the results of comparative analysis of severe accident scenario of total station blackout at WWER-1000 NPP with MELCOR 1.8.5 and 2.1. The comparison demonstrates good agreement between the main parameters’ results (pressure and temperature in hydraulic elements of the primary, secondary sides and the containment, temperature of core elements, the mass of the generated non-condensed gases and their concentration in the containment) obtained with these code versions for severe accident in-vessel phase. The identified differences in the time of core structures degradation and reactor vessel bottom failure are insignificantly affected by the behavior of the parameters in the primary side and the containment in the in-vessel phase of the severe accident and are related to more detailed modelling of the reactor core and bottom part of the reactor in MELCOR 2.1.

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Bhattacharyya, Suvanjan, Devendra Kumar Vishwakarma, Shramona Chakraborty, Rahul Roy, Alibek Issakhov, and Mohsen Sharifpur. "Turbulent Flow Heat Transfer through a Circular Tube with Novel Hybrid Grooved Tape Inserts: Thermohydraulic Analysis and Prediction by Applying Machine Learning Model." Sustainability 13, no. 6 (2021): 3068. http://dx.doi.org/10.3390/su13063068.

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The present experimental work is performed to investigate the convection heat transfer (HT), pressure drop (PD), irreversibility, exergy efficiency and thermal performance for turbulent flow inside a uniformly heated circular channel fitted with novel geometry of hybrid tape. Air is taken as the working fluid and the Reynolds number is varied from 10,000 to 80,000. Hybrid tape is made up of a combination of grooved spring tape and wavy tape. The results obtained with the novel hybrid tape show significantly better performance over individual tapes. A correlation has been developed for predicting the friction factor (f) and Nusselt number (Nu) with novel hybrid tape. The results of this investigation can be used in designing heat exchangers. This paper also presented a statistical analysis of the heat transfer and fluid flow by developing an artificial neural network (ANN)-based machine learning (ML) model. The model is trained based on the features of experimental data, which provide an estimation of experimental output based on user-defined input parameters. The model is evaluated to have an accuracy of 98.00% on unknown test data. These models will help the researchers working in heat transfer enhancement-based experiments to understand and predict the output. As a result, the time and cost of the experiments will reduce.

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Choi, Hwi-Ung, and Kwang-Hwan Choi. "CFD Analysis on the Heat Transfer and Fluid Flow of Solar Air Heater having Transverse Triangular Block at the Bottom of Air Duct." Energies 13, no. 5 (2020): 1099. http://dx.doi.org/10.3390/en13051099.

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In this study, a two-dimensional CFD (computational fluid dynamics) analysis was performed to investigate the heat-transfer and fluid-friction characteristics in a solar air heater having a transverse triangular block at the bottom of the air duct. The Reynolds number, block height (e), pitch (P), and length (l) were chosen as design parameters. The results are validated by comparing the Nusselt number predicted by simulation with available experimental results. Renormalization-group (RNG) k - ε model with enhanced wall-treatment was selected as the most appropriate turbulence model. From the results, it was found that the presence of a transverse triangular block produces a higher Nusselt number than that of smooth air duct. The enhancement in Nusselt number varied from 1.19 to 3.37, according to the geometric conditions investigated. However, the use of transverse triangular block also results in significantly higher friction losses. The thermohydraulic performance (THPP) was also estimated and has a maximum value of 1.001 for height (e) of 20 mm, length (l) of 120 mm, and pitch (P) of 150 mm, at Reynolds number of 8000. Furthermore, in the present study, correlations of the Nusselt number and friction factor were developed as a function of geometrical conditions of the transverse triangular block and Reynolds number, which can be used to predict the value of Nusselt number and friction factor with the absolute percentage deviations of 3.29% and 7.92%, respectively.

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Hans, V. S., R. S. Gill, and Rupinderpal Singh. "Effect of rib roughness pitch on thermal and thermo-hydraulic performance of a solar air heater roughened artificially with arc rib having gap." Journal of Applied and Natural Science 8, no. 1 (2016): 251–56. http://dx.doi.org/10.31018/jans.v8i1.782.

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This experimental study on a solar air heater having absorber plate roughened artificially by providing roughness in the form of arc ribs having gap was carried out in the Department of Mechanical Engineering, Punjab Agricultural University, Ludhiana, India to study the effect of relative roughness pitch on thermal and thermohydraulic performance as well as to compare the performance of arc rib with gap roughened solar air heater with that of continuous arc rib roughened solar air heater. The roughness geometry parameters included relative roughness height of 0.043, angle of attack of 30 degree, relative gap position of 0.80, gap-width equal to the width of the rib and five values of relative roughness pitch ranging from 4 to 12 for flow Reynolds number range of 2000 to 16,000. The Nusselt number and friction factor were found to be more for relative roughness pitch value of 10 as compared to other values of relative roughness pitch. Thermo-hydraulic performance of solar air heaters roughened by arc with gap and continuous arc roughness geometries were found to be 1.91 times and 1.78 times respectively as compared to that of solar air heater having smooth absorber plate due to generation of turbulence in laminar sublayer region. However, improvement in thermo-hydraulic performance of solar air heater roughened by arc with gap geometry over continuous arc rib roughened solar air heater was attributed to generation of a region of turbulence on downstream side of the gap.

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Trunov, N. B., V. I. Melikhov, O. I. Melikhov, and Yu V. Parfenov. "Computational-Theoretical Analysis of the Distribution of the Thermohydraulic Parameters and the Concentration of Dissolved Impurities in a PGV-1000M Horizontal Steam Generator Performed Using the STEG Computer Code." Atomic Energy 96, no. 6 (2004): 407–10. http://dx.doi.org/10.1023/b:aten.0000041208.05809.4a.

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Journal articles on the topic 'Thermohydraulic parameters'

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