scholarly journals Development of Mathematical Model to Predict the Co-Efficient Of Performance in A Refrigeration System Working with R404a

2019 ◽  
Vol 8 (12S2) ◽  
pp. 239-244
Keyword(s):  
Mathematical Model ◽  
Numerical Model ◽  
Loop Length ◽  
Refrigeration System ◽  
Reaction Surface ◽  
Certainty Level

This paper exhibits an orderly way to deal with build up the numerical model for anticipating the coefficient of execution of R 404a which is an eco benevolent refrigerant and broadly utilized in refrigeration and airconditioning ventures. The procedure parameters are loop width, curl pitch and loop length. Reaction surface procedure (RSM) is utilized to build up the scientific model.Analysis of Variance (ANOVA) system is utilized to check the ampleness of the created model. The created numerical model can be utilized adequately at 95% certainty level. The coefficient of execution of R404a in a fume pressure refrigeration framework has been examined in detail.

The mathematical modelling of corrosion in hot dip galvanized steel reinforced concrete

2011 ◽  
Vol 2 (1) ◽  
pp. 1-12
Author(s):  
A. Hegyi ◽  
H. Vermeşan ◽  
V. Rus
Keyword(s):  
Mathematical Model ◽  
Reinforced Concrete ◽  
Numerical Model ◽  
Equation System ◽  
Galvanized Steel ◽  
Steel Reinforced Concrete ◽  
Numeric Model ◽  
Physical And Mathematical Models ◽  
Physical Phenomena ◽  
The Mathematical Model

Abstract In this paper we wish to present the numerical model elaborated in order to simulate some physical phenomena that influence the general deterioration of steel, whether hot dip galvanized or not, in reinforced concrete. We describe the physical and mathematical models, establishing the corresponding equation system, the initial and boundary conditions. We have also presented the numeric model associated to the mathematical model and the numeric methods of discretization and solution of the differential equations system that describes the mathematical model.

Prevention of Corrosion in Austenitic Stainless Steel through a Predictive Numerical Model Simulating Grain Boundary Chromium Depletion

2017 ◽  
pp. 374-389
Author(s):  
M.K. Samal
Keyword(s):  
Mathematical Model ◽  
Stainless Steel ◽  
Austenitic Stainless Steel ◽  
Numerical Model ◽  
Low Temperature ◽  
Grain Boundary ◽  
Stainless Steels ◽  
Predictive Models ◽  
Chromium Depletion ◽  
Sensitization Behavior

In this chapter, a mathematical model for rate of formation of chromium carbides near the grain boundary, which is a pre-cursor to chromium depletion and corresponding sensitization behavior in stainless steels, is presented. This model along with the diffusion equation for chromium in the grain has been used to obtain chromium depletion profiles at various time and temperature conditions. Finite difference method has been used to solve the above equations in the spherical co-ordinate system and the results of time-temperature-sensitization diagrams of four different types of alloys have been compared with those of experiment from literature. For the problem of low temperature sensitization and corresponding inter-granular corrosion in austenitic stainless steel, it is very difficult to carry out experiment at higher temperatures and justify its validity at lower operating temperatures by extrapolation. The development of predictive models is highly useful in order to design the structures for prevention of corrosion of the material in aggressive environments.

scholarly journals Economic Analysis of Solar Refrigeration and Desalination System

2019 ◽  
Vol 118 ◽  
pp. 02021
Author(s):  
Xiaoman Zhang ◽  
Qin Shen ◽  
Shijun Zhu
Keyword(s):  
Mathematical Model ◽  
Economic Analysis ◽  
Physical Model ◽  
Energy Supply ◽  
Recovery Period ◽  
Heat Consumption ◽  
Refrigeration System ◽  
Generation System ◽  
Refrigeration Capacity ◽  
Solar Refrigeration

The physical model and mathematical model of solar refrigeration and desalination co-generation system were established. The performance and economy of the system were analyzed by changing the three variables of refrigeration capacity, seawater desalination effects number and three different cities. The results show that increasing refrigeration capacity is conducive to improving freshwater production and increasing freshwater efficiency, but more auxiliary heat consumption is needed, the comprehensive effect is to shorten the recovery period. Increasing desalination efficiency is conducive to increasing freshwater production and freshwater efficiency, and the auxiliary heat consumption remains unchanged. The comprehensive effect is to shorten the recovery period. Solar energy is the main energy needed in the co-generation system of the three cities, and Shenzhen has the largest proportion of energy supply, which reaches 67.8%. Compared with the solar refrigeration system, the recovery period of the co-generation system can bu shortened by 18.1%.

scholarly journals NUMERICAL MODEL OF BREAKWATER WAVE FLOWS

1988 ◽  
Vol 1 (21) ◽  
pp. 149 ◽  
Author(s):  
Alex C. Thompson
Keyword(s):  
Mathematical Model ◽  
Numerical Model ◽  
Reflection Coefficient ◽  
Water Wave ◽  
Wave Equations ◽  
Seepage Flow ◽  
Experimental Results ◽  
Simplified Model ◽  
Flow Equations ◽  
Shallow Water Wave Equations

A mathematical model of flow on a sloping breakwater face is described and results of calculations compared with some experimental results to show how the model can be calibrated. Flow above the surface of the slope is represented by the shallow water wave equations solved by a finite difference method. Flow within the breakwater is calculated by one of two methods. A solution of the linear seepage flow equations, again using finite differences or a simplified model of inflow can be used. Experimental results for runup and reflection coefficient are from tests performed at HRL Wallingford.

scholarly journals Modeling Drying of Degenerated Calluna vulgaris for Wildfire and Prescribed Burning Risk Assessment

Forests ◽  
2020 ◽  
Vol 11 (7) ◽  
pp. 759 ◽  
Author(s):  
Torgrim Log
Keyword(s):  
Mathematical Model ◽  
Numerical Model ◽  
Mass Loss ◽  
Diffusion Coefficients ◽  
Prescribed Burning ◽  
Fire Hazard ◽  
Fire Risk ◽  
Calluna Vulgaris ◽  
Fire Danger ◽  
Drying Process

Research highlights: Moisture diffusion coefficients for stems and branches of degenerated Calluna vulgaris L. have been obtained and a mathematical model for the drying process has been developed and validated as an input to future fire danger modeling. Background and objectives: In Norway, several recent wildland–urban interface (WUI) fires have been attributed to climate changes and accumulation of elevated live and dead biomass in degenerated Calluna stands due to changes in agricultural activities, i.e., in particular abandonment of prescribed burning for sheep grazing. Prescribed burning is now being reintroduced in these currently fire prone landscapes. While available wildfire danger rating models fail to predict the rapidly changing fire hazard in such heathlands, there is an increasing need for an adapted fire danger model. The present study aims at determining water diffusion coefficients and develops a numerical model for the drying process, paving the road for future fire danger forecasts and prediction of safe and efficient conditions for prescribed burning. Materials and methods: Test specimens (3–6 mm diameter) of dead Calluna stems and branches were rain wetted 48 h and subsequently placed in a climate chamber at 20 °C and 50% relative humidity for mass loss recordings during natural convection drying. Based on the diameter and recorded mass versus time, diffusion coefficients were obtained. A numerical model was developed and verified against recoded mass loss. Results: Diffusion coefficients were obtained in the range 1.66–10.4 × 10−11 m2/s. This is quite low and may be explained by the very hard Calluna “wood”. The large span may be explained by different growth conditions, insect attacks and a varying number of years of exposure to the elements after dying. The mathematical model described the drying process well for the specimens with known diffusion coefficient. Conclusions: The established range of diffusion coefficients and the developed model may likely be extended for forecasting moisture content of degenerated Calluna as a proxy for fire danger and/or conditions for efficient and safe prescribed burning. This may help mitigate the emerging fire risk associated with degenerated Calluna stands in a changing climate.

A numerical method for solving the physics-based model of IGBT with all free-carrier injection conditions in the base region

2017 ◽  
Vol 36 (6) ◽  
pp. 1653-1662 ◽  
Author(s):  
Jiajia Chen ◽  
Yuhan Ma ◽  
Shiyou Yang
Keyword(s):  
Mathematical Model ◽  
Numerical Model ◽  
Design Methodology ◽  
Free Carrier ◽  
Carrier Injection ◽  
Base Region ◽  
Content Type ◽  
Insulated Gate Bipolar Transistor ◽  
Proposed Model ◽  
Solution Methodology

Purpose The purpose of this paper is to provide an accurate model and method to simulate the transient performances of an insulated gate bipolar transistor (IGBT) in an arbitrary free-carrier injection condition. Design/methodology/approach A numerical model and method for solving the physics-based model, an ambipolar diffusion equation-based model, of an IGBT is proposed. Findings The results of the proposed model are very close to the tested ones. Originality/value A mathematical model for an IGBT considering all free-carrier injection conditions is introduced, and a numerical solution methodology is proposed.

scholarly journals Mathematical model of steady flow in a helium loop

2019 ◽  
Vol 20 (7) ◽  
pp. 704
Author(s):  
František Világi ◽  
Branislav Knížat ◽  
Marek Mlkvik ◽  
František Urban ◽  
Róbert Olšiak ◽  
...  
Keyword(s):  
Mathematical Model ◽  
Numerical Model ◽  
Steady Flow ◽  
Gaseous Medium ◽  
Natural Circulation ◽  
Variable Density ◽  
Experimental Facility ◽  
Flowing Medium ◽  
Current State ◽  
Natural Circulation Loop

The article describes the application of a mathematical model to a natural circulation loop. A set of measurements were conducted at the experimental facility. The pressure and velocity relations were observed during the steady flow of helium. The main goal was to create a numerical model of flow capable of determining the velocity of flowing medium. The model describes the flow of highly compressed gaseous medium with variable density in direct pipelines with local resistances. At the current state, the temperature values along the loop are taken as input to the model. The article also includes the evaluation of local resistances in DHR and GFR, which significantly affects the resulting accuracy. The results from a numerical model are compared with experiments.

Design and Analysis of Cooling Cabinet for Vaccine Storage

2014 ◽  
Vol 984-985 ◽  
pp. 1180-1183
Author(s):  
N. Saravanan ◽  
R. Rathnasamy ◽  
V. Ananchasivan
Keyword(s):  
Mathematical Model ◽  
Cooling Effect ◽  
Refrigeration System ◽  
Ansys Software ◽  
Adsorption Refrigeration ◽  
Ammonia Adsorption ◽  
Energy Demands ◽  
Solar Intensity ◽  
Solar Powered ◽  
The Impact

Solar powered adsorption refrigeration system is renewable source in the future energy demands and more useful for off-grid area. In this paper a mathematical model was developed to investigate the performance of a cooling cabinet of a activated carbon-ammonia adsorption refrigeration system, and a new effective method about the refrigeration studies. A brief thermodynamic study of the cooling cabinet is carried out and the effect of operating parameters such as temperature, pressure, cooling effect of the system is numerically analyzed. The impact of solar intensity on performance of the system is significant. The cooling cabinet model is completely analysied for varies capacity and it is able to calculate the cooling cabinet coil length .The designed mathematical model is analyzed by the use of coolpack software and the results are compared with ansys software. It is observed that the system operate more efficient while maximum solar intensity and the cooling effect. Key words: Solar, Adsorption Refrigeration, Mathematical model, Analysis, Solar intensity.

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