The Effect of Condensible Impurities in the Working Fluid on the Performance of Cryogenic Regenerators

1988 ◽  
Vol 110 (1) ◽  
pp. 77-83 ◽  
Author(s):  
R. K. Sahoo ◽  
S. Sarangi
Keyword(s):  
Carbon Dioxide ◽  
Fluid Flow ◽  
Thermal Performance ◽  
Pressure Ratio ◽  
Working Fluid ◽  
Process Stream ◽  
Pressure Cycling ◽  
Flow Parameters ◽  
The Matrix ◽  
Sublimation Curve

In many cryogenic regenerator applications the working fluid contains a small quantity of condensible impurity, which undergoes condensation/evaporation along its sublimation curve due to pressure cycling. The governing differential equations for such a system have been formulated in terms of conventional dimensionless parameters. Numerical solution of these equations is presented for several combinations of fluid flow parameters using nitrogen as the working fluid and carbon dioxide as the impurity. The model indicates that: (a) as long as there is no net accumulation of frost a higher pressure ratio has a negligible effect on the thermal performance of the regenerator; (b) a larger reduced period affects the thermal performance of the regenerator in the presence of a condensible impurity to a greater extent than in the absence of it; (c) the matrix temperature profile undergoes a much larger swing in the presence of a condensible component; and (d) since the exit impurity concentration is a function of reduced length, reduced period, and inlet composition, arbitrarily chosen regenerator parameters cannot be used to purify a warm process stream.

scholarly journals Design of a Semiclosed Cycle Gas Turbine With Carbon Dioxide-Argon as Working Fluid

1997 ◽  
Author(s):  
Inaki Ulizar ◽  
Pericles Pilidis
Keyword(s):  
Carbon Dioxide ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Air Separation ◽  
Working Fluid ◽  
Optimum Pressure ◽  
Low Efficiency ◽  
Nozzle Guide ◽  
Main Engine ◽  
No Emissions

The main performance features of a semiclosed cycle gas turbine with carbon dioxide-argon working fluid are described here. This machine is designed to employ coal synthetic gas fuel and to produce no emissions. The present paper outlines three tasks carried out. Firstly the selection of main engine variables, mainly pressure and temperature ratios. Then a sizing exercise is carried out where many details of its physical appearance are outlined. Finally the off-design performance of the engine is predicted. This two spool gas turbine is purpose built for the working fluid, so its physical characteristics reflect this requirement. The cycle is designed with a turbine entry temperature of 1650 K and the optimum pressure ratio is found to be around 60. Two major alternatives are examined, the simple and the precooled cycle. A large amount of nitrogen is produced by the air separation plant associated with this gas turbine and the coal gasifier. An investigation has been made on how to use this nitrogen to improve the performance of the engine by precooling the compressor, cooling the turbine nozzle guide vanes and using it to cool the delivery of the low pressure compressor. The efficiencies of the whole plant have been computed, taking into account the energy requirements of the gasifier and the need to dispose of the excess carbon dioxide. Hence the overall efficiencies indicated here are of the order of 40 percent. This is a low efficiency by current standards, but the fuel employed is coal and no emissions are produced.

Advances in Computer Aided Engineering for Gas Turbine Research and Development

2021 ◽  
pp. 171-197
Author(s):  
Valeriu Vilag ◽  
Jeni Vilag ◽  
Cleopatra Cuciumita
Keyword(s):  
Carbon Dioxide ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Temperature ◽  
Pressure Ratio ◽  
Thermodynamic Cycle ◽  
Working Fluid ◽  
Atmospheric Air ◽  
Computer Aided ◽  
Main Components

Gas turbines represent energetic machines that operate following the Brayton thermodynamic cycle [6], [16] creating mechanical power and/or thrust. The majority of them use atmospheric air as working fluid but some are working in a closed loop with either air, carbon dioxide or other convenient gas. The main parameters defining the cycle are the combustion temperature and the overall pressure ratio [20]. In principle, the higher the combustion temperature is, the higher the efficiency of the entire gas turbine will be and, for a chosen value of the combustion temperature an optimum overall pressure ratio exists [29]. The main components of the gas turbine are:

scholarly journals Modeling the working media flow in shut-off valves with displacement of the regulating body perpendicular to the flow axis

2021 ◽  
Vol 2057 (1) ◽  
pp. 012017
Author(s):  
V V Soloveva ◽  
A S Pugachuk ◽  
A V Chernyschev
Keyword(s):  
Fluid Flow ◽  
Gas Flow ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Flow Section ◽  
Flow Parameters ◽  
Wide Range ◽  
Flow Part ◽  
Flow Through ◽  
Working Media

Abstract The mathematical model of the working fluid movement in the flow section of the wedge type two-disc parallel gate valve is developed. The simulation of the fluid flow through the valve cavity is carried out, as a result the flow parameters are obtained in a wide range of Reynolds numbers at the entrance to the calculated area. The dependence of the hydraulic resistance as a function of the Reynolds number for liquid and gas flow is calculated. The various positions of the shut-off body in the flow part of the valve are considered and the area of reduced pressures in which the effect of cavitation may occur during fluid flow is estimated.

Effect of the Specific Heat Ratio on the Aerodynamic Performance of Turbomachinery

2002 ◽  
Vol 127 (4) ◽  
pp. 773-780 ◽  
Author(s):  
Stephen K. Roberts ◽  
Steen A. Sjolander
Keyword(s):  
Specific Heat ◽  
Pressure Ratio ◽  
Working Fluid ◽  
Turbine Engines ◽  
Gas Turbine Engines ◽  
Working Fluids ◽  
Specific Heat Ratio ◽  
Flow Parameters ◽  
Isentropic Flow ◽  
Compressor Map

Many gases, including carbon dioxide and argon, have been considered as alternative working fluids to air in a number of design studies for closed and semi-closed gas turbine engines. In many of these studies, it has been assumed that if the gas constant R and specific heat ratio γ are included in the speed and flow parameters, the compressor map or turbine characteristic is applicable to other working fluids. However, similarity arguments show that the isentropic exponent itself is a criterion of similarity and that the turbomachinery characteristics, even when appropriately nondimensionalized, will, in principle, vary as the γ of the working fluid varies. This paper examines the effect of γ on turbomachinery characteristics, mainly in terms of compressors. The performance of a centrifugal compressor stage was measured using air (γ=1.4), CO2(γ=1.29), and argon (γ=1.67). For the same values of the nondimensional speed, the pressure ratio, efficiency, and choking mass flow were found to be significantly different for the three test gases. The experimental results have been found to be consistent with a CFD analysis of the impeller. Finally, it is shown that the changes in performance can be predicted reasonably well with simple arguments based mainly on one-dimensional isentropic flow. These arguments form the basis for correction procedures that can be used to project compressor characteristics measured for one value of γ to those for a gas with a different value.

Performance Analysis of Printed Circuit Heat Exchanger for Supercritical Carbon Dioxide

2017 ◽  
Vol 139 (6) ◽  
Author(s):  
Jiangfeng Guo ◽  
Xiulan Huai
Keyword(s):  
Heat Transfer ◽  
Carbon Dioxide ◽  
Heat Exchanger ◽  
Supercritical Carbon Dioxide ◽  
Entropy Generation ◽  
Thermal Performance ◽  
Transfer Entropy ◽  
Working Fluid ◽  
Printed Circuit ◽  
Supercritical Carbon

A printed circuit heat exchanger (PCHE) was selected as the recuperator of supercritical carbon dioxide (S-CO2) Brayton cycle, and the segmental design method was employed to accommodate the rapid variations of properties of S-CO2. The local heat capacity rate ratio has crucial influences on the local thermal performance of PCHE, while having small influences on the frictional entropy generation. The heat transfer entropy generation is far larger than the frictional entropy generation, and the total entropy generation mainly depends on the heat transfer entropy generation. The axial conduction worsens the thermal performance of PCHE, which becomes more and more obvious with the increase of the thickness and thermal conductivity of plate. The evaluation criteria, material, and size of plate have to be selected carefully in the design of PCHE. The present work may provide a practical guidance on the design and optimization of PCHE when S-CO2 is employed as working fluid.

Design of a Semiclosed-Cycle Gas Turbine With Carbon Dioxide–Argon as Working Fluid

1998 ◽  
Vol 120 (2) ◽  
pp. 330-335 ◽  
Author(s):  
I. Ulizar ◽  
P. Pilidis
Keyword(s):  
Carbon Dioxide ◽  
Gas Turbine ◽  
Pressure Ratio ◽  
Air Separation ◽  
Working Fluid ◽  
Optimum Pressure ◽  
Low Efficiency ◽  
Nozzle Guide ◽  
Main Engine ◽  
No Emissions

The main performance features of a semiclosed-cycle gas turbine with carbon dioxide–argon working fluid are described here. This machine is designed to employ coal synthetic gas fuel and to produce no emissions. The present paper outlines three tasks carried out. First, the selection of main engine variables, mainly pressure and temperature ratios. Then a sizing exercise is carried out where many details of its physical appearance are outlined. Finally the off-design performance of the engine is predicted. This two-spool gas turbine is purpose built for the working fluid, so its physical characteristics reflect this requirement. The cycle is designed with a turbine entry temperature of 1650 K and the optimum pressure ratio is found to be around 60. Two major alternatives are examined, the simple and the precooled cycle. A large amount of nitrogen is produced by the air separation plant associated with this gas turbine and the coal gasifier. An investigation has been made on how to use this nitrogen to improve the performance of the engine by precooling the compressor, cooling the turbine nozzle guide vanes, and using it to cool the delivery of the low-pressure compressor. The efficiencies of the whole plant have been computed, taking into account the energy requirements of the gasifier and the need to dispose of the excess carbon dioxide. Hence the overall efficiencies indicated here are of the order of 40 percent. This is a low efficiency by current standards, but the fuel employed is coal and no emissions are produced.

scholarly journals High-Speed Visual Analysis of Fluid Flow and Heat Transfer in Oscillating Heat Pipes with Different Diameters

2016 ◽  
Author(s):  
Xiangdong Liu ◽  
Qing Sun ◽  
Chengbin Zhang ◽  
Liangyu Wu
Keyword(s):  
Heat Transfer ◽  
Fluid Flow ◽  
Thermal Performance ◽  
Slug Flow ◽  
High Speed ◽  
Bubbly Flow ◽  
Heat Pipes ◽  
Working Fluid ◽  
Flow And Heat Transfer ◽  
Inner Diameter

The oscillating heat pipe (OHP) is a new member in the family of heat pipes, and it has great potential applications in energy conservation. However, the fluid flow and heat transfer in the OHP as well as the fundamental effects of inner diameter on them have not been fully understood, which are essential to the design and optimization of the OHP in real applications. Therefore, by combining the high-speed visualization method and infrared thermal imaging technique, the fluid flow and thermal performance in the OHPs with inner diameters of 1, 2 and 3 mm are presented and analyzed. The results indicate that three fluid flow motions, including small oscillation, bulk oscillation and circulation, coexist or, respectively, exist alone with the increasing heating load under different inner diameters, with three flow patterns occurring in the OHPs, viz. bubbly flow, slug flow and annular flow. These fluid flow motions are closely correlated with the heat and mass transfer performance in the OHPs, which can be reflected by the characteristics of infrared thermal images of condensers. The decrease in the inner diameter increases the frictional flow resistance and capillary instability while restricting the nucleate boiling in OHPs, which leads to a smaller proportion of bubbly flow, a larger proportion of short slug flow, a poorer thermal performance, and easier dry-out of working fluid. In addition, when compared with the 2 mm OHP, the increasing role of gravity induces the thermosyphon effect and weakens the 'bubble pumping' action, which results in a little smaller and bigger thermal resistances of 3 mm OHP under small and bulk oscillation of working fluid, respectively.

Experimental study of thermohydraulic characteristics and irreversibility analysis of novel axial corrugated tube with spring tape inserts

2020 ◽  
Vol 92 (3) ◽  
pp. 30901
Author(s):  
Suvanjan Bhattacharyya ◽  
Debraj Sarkar ◽  
Ulavathi Shettar Mahabaleshwar ◽  
Manoj K. Soni ◽  
M. Mohanraj
Keyword(s):  
Heat Transfer ◽  
Experimental Study ◽  
Thermal Performance ◽  
Working Fluid ◽  
The Novel ◽  
Heat Exchanger Tube ◽  
Heat Transfer Augmentation ◽  
Corrugated Tube ◽  
The Impact ◽  
Exchanger Tube

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.

Significance of Mineralogical and Lithologic-Petrographical Rank in the Ranking of Geological Information

2020 ◽  
Vol 42 (4) ◽  
pp. 33-49
Author(s):  
O.V. CHEPIZHKO ◽  
V.V. YANKO ◽  
V.M. KADURIN ◽  
I.M. NAUMKO ◽  
S.M. SHATALIN
Keyword(s):  
Fluid Flow ◽  
Black Sea ◽  
Bottom Sediments ◽  
Oil And Gas ◽  
Sedimentary Cover ◽  
Geochemical Characteristics ◽  
The Black Sea ◽  
Flow Parameters ◽  
Geochemical Parameters ◽  
Geological Information

For the first time the importance of mineralogical and lithological-petrographical ranks in the line of geological information ranks is substantiated for implementation of long-term forecasts, standard and non-standard approaches to research of physical and geochemical parameters as a basis of creation of complex system of forecast criteria and prospecting indicators of hydrocarbons within the sedimentary cover of Black sea based on the theory of global fluid-flows derivation. These criteria have different sensitivity to the object (hydrocarbon deposits) and are therefore ranked. The ranking determined the following parameters: 1) seismic data within the object, obtained by the method of deep seismic sounding, RWM SDP; 2) parameters of tectono-geodynamic structures; 3) the main characteristics of sedimentary cover and bedrock; 4) geochemical characteristics; 5) parameters of mineral complexes and fluid inclusions in mineral neoformations; 6) the value of the distribution of meiobenthos. Based on modern views of oil and gas geology, structural-tectonic and lithological-facies criteria are among the main ones. The study of the mineralogical component of sediments is made with using mineralogical, thermobarogeochemical and X-ray spectral methods. Fixation of anomalies of fluid flow at the bottom of the Black Sea as to the distribution of abiotic parameters in order to assess the prospects of oil and gas is determined by structural and tectonic features and high permeability of fluid flow; parameters of mineral complexes (minerals, facies) and genetic connections; heterogeneity of geochemical characteristics of bottom sediments; the presence of hydrocarbon inclusions in authigenic minerals of bottom sediments.

Sign in / Sign up

Export Citation Format

Share Document