Igor Pioro

Heat transfer and hydraulic resistance at supercritical pressures in power-engineering applications

Mechanical and Nuclear Engineers are currently working on advanced power plants intended for implementation within the next decade. One such Generation IV concept is a supercritical, water-cooled nuclear reactor. In addition, there are already hundreds of supercritical steam generators operating worldwide in the thermal power industry. These system designs reduce emissions and lower cost by attaining high thermodynamic cycle and economic efficiency, utilizing both natural and forced circulation flows and optimizing heat exchanger and turbine layout and performance. Development, design, and successful operation of these power-generating units require knowledge of heat transfer, pressure drop, and thermalhydraulics at supercritical pressures. Demand for reliable information is high, and until now, no single book related to this topic has been published.This book brings together and integrates the results from over 500 of the latest sources from the global publications devoted to heat transfer and hydraulic resistance of fluids flowing inside channels of various geometries at near-critical and supercritical pressures. This book is of interest to nuclear and mechanical engineers in both industry and academia, who are concerned with the development and design of next-generation reactors, as well as engineers and technologists currently working with supercritical steam generators and power systems. Included with this book is a free CD containing fully linked references to help readers navigate the welath of material that is provided.

Experimental evaluation of constants for the Rohsenow pool boiling correlation

Abstract The present experimental study is concerned with heat transfer under nucleate boiling of fluids on the horizontal thick plates made from copper, aluminum, brass and stainless steel. Reported are the results of the effect of the heat flux, the saturation pressure from near atmospheric to vacuum, and the thermophysical properties of four working fluids (water, ethanol, R-113, and R-11) on the heat transfer coefficient under boiling. To quantify the effect of these parameters on the heat transfer coefficient, the Rohsenow pool boiling correlation was used with the constants from the experiment. The experimental data match the data of other investigators. Previous experimental works were analysed to evaluate the prediction intervals of the Rohsenow pool boiling correlation for different surface–fluid combinations.

Reprocessing of metallurgical slag into materials for the building industry

Several methods of reprocessing metallurgical (blast furnace) slag into materials for the building industry, based on melting aggregates with submerged combustion, were developed and tested. The first method involves melting hot slag with some additives directly in a slag ladle with a submerged gas-air burner, with the objective of producing stabilized slag or glass-ceramic. The second method involves direct draining of melted slag from a ladle into the slag receiver, with subsequent control of the slag draining into the converter where special charging materials are added to the melt, with the objective of producing glass-ceramic. A third method involves melting cold slag with some additives inside a melting converter with submerged gas-air burners, with the objective of producing glass-ceramic fillers for use in road construction. Specific to the melting process is the use of a gas-air mixture with direct combustion inside the melt. This feature provides melt bubbling to help achieve maximum heat transfer from combustion products to the melt, improve mixing (and therefore homogeneity of the melt), and increases the rate of chemical reactions. The experimental data for different aspects of the proposed methods are presented. The reprocessed blast-furnace slag in the form of granules can be used as fillers for concretes, asphalts, and as additives in the production of cement, bricks and other building materials. As well, reprocessed blast-furnace slag can be poured into forms for the production of glass-ceramic tiles.

Comparison of CHF measurements in R-134a cooled tubes and the water CHF look-up table

An exhaustive experimental study of the critical heat flux (CHF) in R-134a-cooled tubes has been recently completed. The objective of this study was to provide a consistent set of CHF data to be used as a reference for future separate effect studies. The investigated range of flow parameters in R-134a was: outlet pressure 0.96–2.39 MPa (equivalent to 6–14 MPa in water), mass flux 500–3000 kg m−2 s−1 (equivalent to 700–4300 kg m−2 s−1 in water), and critical quality −0.1 to +0.9. To extend the range of critical qualities, different heated lengths (0.45–2 m) and two-phase flow at inlet to the test section were used. Scaling laws were applied to convert the standard CHF look-up table from water to R-134a equivalent conditions. The comparison of the data with the water-based look-up table showed that for high mass fluxes (G = 1400–4300 kg m−2 s−1 in water equivalent), the look-up table provides an excellent CHF prediction for R-134a-cooled tubes. The differences were mainly noticeable for the limiting critical quality range and for low mass flux. A discussion of the observed limiting critical quality phenomenon is also included.

Thermal-Design Options for Pressure-Channel SCWRS With Cogeneration of Hydrogen

Currently there are a number of Generation IV supercritical water-cooled nuclear reactor (SCWR) concepts under development worldwide. The main objectives for developing and utilizing SCWRs are (1) to increase the gross thermal efficiency of current nuclear power plants (NPPs) from 33-35% to approximately 45-50% and (2) to decrease the capital and operational costs and, in doing so, decrease electrical-energy costs (approximately US

Specifics of thermophysical properties and forced-convective heat transfer at critical and supercritical pressures

1000/kW or even less). SCW NPPs will have much higher operating parameters compared to current NPPs (i.e., pressures of about 25 MPa and outlet temperatures of up to 625 °C). Additionally, SCWRs will have a simplified flow circuit in which steam generators, steam dryers, steam separators, etc. will be eliminated. Furthermore, SCWRs operating at higher temperatures can facilitate an economical cogeneration of hydrogen through thermochemical cycles (particularly, the copper-chlorine cycle) or direct high-temperature electrolysis. To decrease significantly the development costs of a SCW NPP and to increase its reliability, it should be determined whether SCW NPPs can be designed with a steam-cycle arrangement that closely matches that of mature supercritical (SC) fossil power plants (including their SC turbine technology). On this basis, several conceptual steam-cycle arrangements of pressure-channel SCWRs, their corresponding T-s diagrams and steam-cycle thermal efficiencies are presented in this paper together with major parameters of the copper-chlorine cycle for the cogeneration of hydrogen. Also, bulk-fluid temperature and thermophysical properties profiles were calculated for a nonuniform cosine axial heat-flux distribution along a generic SCWR fuel channel, for reference purposes.

Comparison of CHF measurements in horizontal and vertical tubes cooled with R-134a

Abstract Investigation of heat transfer at supercritical pressures began as early as the 1930s, with the study of free-convection heat transfer to fluids at the near-critical point. In the 1950s, the concept of using supercritical “steam” to increase the thermal efficiency of fossil-fired power plants became an attractive option. Currently, using supercritical “steam” in fossil-fired power plants is the largest industrial application of fluids at supercritical pressures. Near the end of the 1950s and at the beginning of the 1960s, several studies were conducted to investigate the potential of using supercritical water as a coolant in nuclear reactors. The USA and the former USSR extensively studied supercritical heat transfer during the 1950s until the 1980s. Research primarily focused around circular water-cooled tube flow geometry. The primary objectives for using supercritical water as a coolant in nuclear reactors are: (1) to increase the thermal efficiency of modern nuclear power plants, which is currently 30–35%, to approximately 45% or higher, and (2) to decrease the operational and capital costs by eliminating steam generators, steam separators, steam dryers, etc. In support of the development of a supercritical water-cooled nuclear reactor, it is necessary to perform a heat-transfer analysis. As a first step in this process, heat-transfer to supercritical water in bare vertical tubes can be investigated as a conservative approach (in general, heat-transfer in fuel bundles will be enhanced with various types of appendages, i.e., bearing pads, end plates, fins, ribs, spacers, etc.). A comparison of selected supercritical-water heat-transfer correlations has shown that their results may differ from one another by more than 200%. Based on these comparisons, it became evident that there is a need to use a reliable, accurate and wide-range supercritical-water heat-transfer correlation. For this reason, the new or recently updated Mokry et al. (2009) correlation was used in the presented analyses. Other areas exist in which supercritical fluids are used, or will be implemented in the near future. These include, for example, using SuperCritical Water Oxidation (SCWO) technology for the treatment of industrial and military wastes, using carbon dioxide in the Supercritical Fluid Leaching (SFL) method for the removal of uranium from radioactive solid wastes and in the decontamination of surfaces, and using supercritical fluids in chemical and pharmaceutical industries, in such processes as supercritical fluid extraction, supercritical fluid chromatography, polymer processing, and others. The objective of this review is to assess the work performed concerning thermophysical properties and the associated heat transfer and pressure drop at supercritical pressures, based on examples of water and carbon dioxide.

Research and development of a high-efficiency one-stage melting converter-burial-bunker method for vitrification of high-level radioactive wastes

An experimental study of the critical heat flux (CHF) in horizontal and vertical tubes cooled with R-134a has been completed. The investigated ranges of flow parameters in R-134a were outlet pressures of 1.31, 1.67 and 2.03 MPa (8, 10 and 12 MPa in water-equivalent values), mass flux from 500 to 3000 kg m � 2 s � 1 (700–4300 kg m � 2 s � 1 in water-equivalent values), and critical quality from )0.1 to þ0.9. The wide range of qualities was achieved using tubes of different heated lengths and two-phase flow at the test-section inlet. The R-134a CHF data obtained in the vertical orientation agreed with the R-134a-equivalent CHF values from the water-based CHF look-up table. The effect of orientation on CHF was found to depend on mass flux, quality and pressure, as well as the limiting critical quality. This effect is strong at low mass fluxes, but disappears at high mass fluxes. At qualities higher than the limiting critical qualities, the CHF in horizontal flow can be greater than the corresponding value in vertical flow at the same critical quality conditions. A maximum reduction in CHF due to flow stratification was observed at qualities between the limiting critical qualities for horizontal and vertical flows. The orientation effect on CHF appears to be much stronger for R-134a than for water flow at the same critical quality, equivalent mass flux (based on vertical flow fluid-to-fluid modeling relationships) and density ratio. This behavior is primarily due to the larger density difference between liquid and vapor and the lower vapor velocity in R-134a. � 2002 Elsevier Science Ltd. All rights reserved.

Conceptual Thermal-Design Options for Pressure-Tube SCWRs With Thermochemical Co-Generation of Hydrogen

A new high-efficiency one-stage melting converter-burial-bunker method for vitrification of high-level radioactive wastes has been developed and investigated. The method includes evaporation (concentration), calcination, and vitrification of high-level radioactive wastes in a one-stage process inside a melting converter for non-metallic minerals, followed by burial inside a bunker-storage facility located directly underneath a melting chamber. Specific to the melting process is the direct combustion of a gas-oxygen-air mixture inside a melt. The experimental data for different aspects of the proposed method are presented, including converter/bunker dimensions, burner types and sizes, data for used materials, contents of saturated salty solution and final glass product, and entrainment analysis. The effective flue-gases cleaning systems and the design of the burial-bunker storage facility are also discussed.

Handbook of Generation-IV Nuclear Reactors

Currently there are a number of Generation IV SuperCritical Water-cooled nuclear Reactor (SCWR) concepts under development worldwide. The main objectives for developing and utilizing SCWRs are: 1) To increase gross thermal efficiency of current Nuclear Power Plants (NPPs) from 33–35% to approximately 45–50%, and 2) To decrease the capital and operational costs and, in doing so, decrease electrical-energy costs (∼