Numerical Simulation of Steam Flow Inside the Superheater Section of An Industrial Boiler Using a Real Gas Model

2020 ◽  
Vol 142 (7) ◽  
Author(s):  
Deepak Kumar Kanungo ◽  
Kirti Chandra Sahu
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Supercritical Fluids ◽  
Ideal Gas ◽  
Real Gas ◽  
Absolute Value ◽  
Ideal Gas Law ◽  
Maximum Value ◽  
Industrial Boiler ◽  
The Ideal

Abstract Flow mal-distribution inside manifolds hampers the overall efficiency of processes in industries. In supercritical boilers, improper flow of steam inside the superheater (SH) section is a common cause of thermal accidents. However, carrying out a numerical simulation of supercritical fluids flowing inside manifolds is challenging as the ideal gas law does not describe the behavior of these fluids properly. In the present work, numerical simulation of the flow of supercritical steam inside the superheater section of an industrial boiler has been performed using a real gas model. The proposed real gas model is first validated with experimental data associated with the steam properties. Subsequently, the effect of different inlet and outlet arrangements on the flow mal-distribution of steam in the superheater section of the boiler is investigated numerically using the real gas model. A modified inlet and outlet arrangement of the superheater header is proposed which reduces the maximum value of flow mal-distribution in the header by 19.7% and total pressure drop in the domain by 17%. The effect of the Reynolds number on flow mal-distribution in the header arrangement is found to be negligible. The absolute value of the heat absorption by the superheater tubes increases with an increase in the value of the Reynolds number.

Making sense of sensemaking: using the sensemaking epistemic game to investigate student discourse during a collaborative gas law activity

2021 ◽  
Author(s):  
Kevin H. Hunter ◽  
Jon-Marc G. Rodriguez ◽  
Nicole M. Becker
Keyword(s):  
Problem Solving ◽  
Conceptual Understanding ◽  
Ideal Gas ◽  
Interactive Simulation ◽  
Structural Components ◽  
Student Discourse ◽  
Coding Scheme ◽  
Making Sense ◽  
Ideal Gas Law ◽  
The Ideal

Beyond students’ ability to manipulate variables and solve problems, chemistry instructors are also interested in students developing a deeper conceptual understanding of chemistry, that is, engaging in the process of sensemaking. The concept of sensemaking transcends problem-solving and focuses on students recognizing a gap in knowledge and working to construct an explanation that resolves this gap, leading them to “make sense” of a concept. Here, we focus on adapting and applying sensemaking as a framework to analyze three groups of students working through a collaborative gas law activity. The activity was designed around the learning cycle to aid students in constructing the ideal gas law using an interactive simulation. For this analysis, we characterized student discourse using the structural components of the sensemaking epistemic game using a deductive coding scheme. Next, we further analyzed students’ epistemic form by assessing features of the activity and student discourse related to sensemaking: whether the question was framed in a real-world context, the extent of student engagement in robust explanation building, and analysis of written scientific explanations. Our work provides further insight regarding the application and use of the sensemaking framework for analyzing students’ problem solving by providing a framework for inferring the depth with which students engage in the process of sensemaking.

A NUMERICAL STUDY OF FLUID INJECTION AND MIXING UNDER NEAR-CRITICAL CONDITIONS

2012 ◽  
Vol 19 ◽  
pp. 39-49 ◽  
Author(s):  
HUA-GUANG LI ◽  
XI-YUN LU ◽  
VIGOR YANG
Keyword(s):  
Reynolds Number ◽  
Shear Layer ◽  
Numerical Study ◽  
Ideal Gas ◽  
Critical Conditions ◽  
Reference Case ◽  
Nitrogen Injection ◽  
Volume Dilatation ◽  
High Reynolds ◽  
The Ideal

Nitrogen injection under conditions in close vicinity of liquid-gas critical point is studied through numerical simulation. The thermodynamic and transport properties of fluid exhibit anomalies in the near-critical fluid regime. These anomalies can cause distinctive effects on heat transfer and hydrodynamics. To focus on the influence of the highly variable properties and avoid the difficulties encountered in modeling high Reynolds number flows, a relatively low injection Reynolds number is adopted. A reference case with the same configuration and Reynolds number is also simulated in the ideal gas regime. Full conservation laws, real-fluid thermodynamic and transport phenomena are accommodated in the model. The obtained results reveal that the flow features of the near-critical fluid jet are significantly different from the ideal gas case. The near-critical fluid jet spreads faster and mixes better with the ambient fluid compared to the ideal gas jet. It is also identified that vortex pairing process develops faster in the near-critical case than in the ideal gas case. Detailed analysis of data at different streamwise positions including both flat shear layer region and fully developed vortex region reveals the effect of volume dilatation and baroclinic torque plays an important role in the near-critical fluid case. The volume dilatation effect disturbs the shear layer and makes it more unstable. The volume dilatation and baroclinic effects strengthen the vorticity and stimulate the vortex rolling up and pairing process.

What Happens When We have Winter Heating of Our Rooms?

2020 ◽  
Vol 02 (01) ◽  
pp. 2020001
Author(s):  
Dulli C. Agrawal
Keyword(s):  
Internal Energy ◽  
Old Age ◽  
Ideal Gas ◽  
Van Der Waals Gas ◽  
Constant Weight ◽  
Gas Laws ◽  
Ideal Gas Law ◽  
Marginal Change ◽  
Three Stages ◽  
The Ideal

The illustrious question by German Astrophysicist R. Emden, “Why do we have winter heating?” has been re-examined for air following both the ideal and imperfect gas laws; the internal energy of the air in the room remains unaffected in the former case whereas it increases marginally for the latter one. The findings corresponding to ideal gas law were correlated by Emden with the mass of a person which does not change even though food is constantly consumed. This example corresponds to adulthood when the mass of a person remains more or less constant. But the marginal change of internal energy in the case of van der Waals gas is consistent with three stages of a person — initially a person grows during childhood followed by adulthood when he has more or less constant weight and finally in old age, it deteriorates.

Supercooling in hypersonic nitrogen wind tunnels

1994 ◽  
Vol 269 ◽  
pp. 283-299 ◽  
Author(s):  
Wayland C. Griffith ◽  
William J. Yanta ◽  
William C. Ragsdale
Keyword(s):  
Vibrational Energy ◽  
Ideal Gas ◽  
Wind Tunnels ◽  
Pure Nitrogen ◽  
Real Gas ◽  
Absolute Limit ◽  
Real Gas Effects ◽  
Supercooled Region ◽  
The Ideal

Recent experimental observation of supercooling in large hypersonic wind tunnels using pure nitrogen identified a broad range of non-equilibrium metastable vapour states of the flow in the test cell. To investigate this phenomenon a number of real-gas effects are analysed and compared with predictions made using the ideal-gas equation of state and equilibrium thermodynamics. The observed limit on the extent of supercooling is found to be at 60% of the temperature difference from the sublimation line to Gibbs’ absolute limit on phase stability. The mass fraction then condensing is calculated to be 12–14%. Included in the study are virial effects, quantization of rotational and vibrational energy, and the possible role of vibrational relaxation and freezing in supercooling. Results suggest that use of the supercooled region to enlarge the Mach–Reynolds number test envelope may be practical. Data from model tests in supercooled flows support this possibility.

Heat Transfer and Pressure Drop Through Nano-Fin Arrays in the Free-Molecular Flow Regime

2012 ◽  
Author(s):  
Michael James Martin
Keyword(s):  
Heat Transfer ◽  
Pressure Drop ◽  
Gas Flow ◽  
Ideal Gas ◽  
Molecular Flow ◽  
Ideal Gas Law ◽  
Transfer Equations ◽  
Flow Through ◽  
The One ◽  
The Ideal

Gas flow through arrays of rectangular nano-fins is modeled using the linearized free-molecular drag and heat transfer equations. These are combined with the one-dimensional equations for conservation of mass, momentum, and energy, and the ideal gas law, to find the governing equations for flow through the array. The results show that the pressure gradient, temperature, and local velocity of the gas are governed by coupled ordinary differential equations. The system of equations is solved for representative arrays of nano-fins to find the total heat transfer and pressure drop across a 1 cm chip.

Simple Predictions for the Sonic Conditions in a Real Gas

1977 ◽  
Vol 99 (1) ◽  
pp. 217-225 ◽  
Author(s):  
P. A. Thompson ◽  
D. A. Sullivan
Keyword(s):  
Equation Of State ◽  
Closed Form ◽  
Thermodynamic Parameters ◽  
Ideal Gas ◽  
Accurate Prediction ◽  
Bernoulli Equation ◽  
Real Gas ◽  
Similarity Principle ◽  
Isentropic Flow ◽  
The Ideal

The steady isentropic flow of a fluid which satisfies an arbitrary equation of state is treated, with emphasis on the prediction of pressure, density, velocity, and massflow at the sonic state. The isentrope P(v) is described by a limited number of thermodynamic parameters, the most important ones being the soundspeed c and fundamental derivative Γ. Using this description, an application of the Bernoulli equation and appropriate thermodynamic relations yields simple closed-form predictions for the sonic state. These predictions are recognizable as generalizations of well-known ideal gas formulas, but are applicable to fluids very far removed from the ideal gas state, even including liquids. Comparisons in several cases for which precise independent solutions are available suggest that the methods found here are accurate. A derived similarity principle allows the accurate prediction of sonic properties from any single given sonic property.

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