EGH422 Advanced Thermodynamics Practical Report

Assignment

Mechanical Engineering

Variation of Specific Heat Capacity with Temperature

Table of Contents

Introduction

The nature of the burn is reflected in lots of day by day activities, which inspire many researchers to discover the sector. The heating quarter has advanced significantly in the last few a long time. Our research is aimed at studying the chemical composition and combustion of fuel in a rectangular combustor, combustible methane (CH4) inside the air studied using a standardized chemistry version the use of the eddy-dissipation approach. The eddy-dissipation version is less expensive mathematically, but for realistic effects, only one or step-by way of-step heat dissipation methods need to be used. It requires much less calculation time and isn’t always suitable for multi-step response. Flow simulation using CFD Package, Fluent. Three forms of boundary situations had been used to define the waft area inside the calculation area .Frame parameters which includes pace, temperature, turbulence depth, Hydraulic variety are defined prior to simulation. This hassle analyzes the mixing of chemical substances and the combustion of gasoline gasoline. The rectangular flamable methane (CH4) combustor inside the air is investigated the use of a standardized chemistry model the usage of the evaluation software, Fluent. Many researchers have labored in this area by means of exploring and calculating to take a look at what is occurring oh the burning process. Some of them are indexed right here. B. Reveille and A. Duparchy [1] worked on 3D CFD evaluation of Unusual Burnout phenomenon on reduced gasoline engines. This paper focuses on some thing very fast, however no longer unfavorable and apparently solid that has been visible at low speeds during heavy workloads as they’re reduced by way of various engines.

Materials and Methods

Rectangular combustor length = 3meter, width = 0. 56meters, length = 0.6 meters is taken into consideration on this analysis as shown in Figure underneath:

The proposed flame is a flame distribution flame. Two small tubes with a diameter of 10 mm every are supplied to a rectangular fireplace machine to supply methane at 100 m / s as gasoline. Ambient air enters the combustor at 3 m / s. The standard equity is envisioned at 0.79. A excessive-speed methane jet to start with grows with a slight disturbance from the outer wall, and penetrates and mixes with low-velocity air. Here we are able to use a standardized wellknown chemical version to investigate the methane air heating system the use of the eddy-dissipation method. The combustion could be modeled the usage of a single step reaction considering the whole conversion of gas to CO2 and H2O. The reaction rate is

Boundary Conditions

In this case, 3 types of boundary conditions were used for fluid flow. They are discussed below:

Velocity Inlet Boundary Conditions:

These are used to explain the go with the flow rate, as well as all the suitable scalar glide characteristics, in glide inlets. The overall (or stop) go with the flow charge isn’t always adjusted, so it’ll boom to any cost needed to offer a hard and fast velocity distribution. This boundary condition is designed for non-compressed waft, and its use in compressed waft will result in a non-physical effect because it allows status situations to glide at any degree. You ought to also be cautious no longer to place the doorway pace too near a solid impediment, as this will reason the design functions of your access to be less uniform.

Pressure Outlet Boundary Conditions

This calls for the specification of stationary pressure (gauge) on the go out boundary. The stated static strain price is most effective used whilst the float is under subsonic. If the flow becomes a neighborhood supersonic, the stated strain will not observe; pressure might be introduced to the internal float. All other glide values are excluded internally. A set of “reversal” conditions is likewise certain whilst the flow returns to the stress release threshold in the course of the answer process. Integration problems will be decreased in case you specify the actual return values.

Ball Boundary Conditions

These are used to bind liquid and solid areas. In viscous float, the slippery boundary situation is pressured into the partitions robotically, however you may specify a part of the tangential pace in terms of translation or rotation of the wall boundary, or the “sliding” wall model through specifying the shear. (You can also version a easy wall with zero shear using the kind of boundary symmetry, however using the symmetry boundary will observe measuring conditions in all calculations. The shear stress and heat transfer between the liquid and the wall are calculated electronically based totally at the float information of the nearby waft subject.

Results

Iteration obtained, when specific heat capacity was kept constant:

It was observed, that the convergence was obtained at about 424 iterations.

Solution obtained, when specific heat capacity was kept constant:

The static temperature from the photo above suggests the fact that the ambient temperature could be very high close to 2.63e + 03 K at 1/3 of the fire chamber which means that the fire temperature reaches the very best temperature compared to the go out. 2.1e + 03 K. Here the direct temperature taken through regular (Cp) as proven in the figure below:

High temperature is anticipated using a regular temperature of 1000 J / kg-K, above 2600 K. This prediction above the temperature of a hearth can be adjusted by way of a practical temperature model and dependent on the temperature structure.

Iteration Obtained, when specific heat capacity was not constant:

It was seen that the convergence was obtained in about 135 iterations

Solution obtained, when specific heat capacity was not constant:

From the above figure it seems that, with variable Cp, the output temperature from the combustion chamber is 1.14e + 03 K, which may be very low as compared to continuous Cp. In the first phase of the combustion chamber the most temperature is approximately 1.82e + 03 K and compared to the regular Cp, it is very low which shows the importance of direct temperature in phrases of combustion.

Conclusion

It is concluded that when continuous direct specific heat is taken, the approach of managing it is unrealistic. This overheating of the fire temperature may be corrected by using a realistic temperature model and the dependence of the warmth composition and flame length is a great deal shorter at the variable Cp in comparison to the constant Cp, Although the flexible Cp answer produces dramatic improvements. Inside the anticipated consequences, similarly development is viable via considering the extra models and functions discovered in Fluent.

References

Abah, E. O., Ahamed, T., & Noguchi, R. (2021). Catalytic Temperature Effects on Conversion Efficiency of PM2.5 and Gaseous Emissions from Rice Husk Combustion. Energies, 14(19), 6131. https://doi.org/10.3390/en14196131

Pandey, K. M., Das, D. H., & Acharya, B. (2010). Effects of Variation of Specific Heat on Temperature in Gaseous Combustion with Fluent Software. International Journal of Environmental Science and Development, 419–422. https://doi.org/10.7763/ijesd.2010.v1.80

Réveillé, B., & Duparchy, A. (2009). 3D CFD Analysis of an Abnormally Rapid Combustion Phenomenon in Downsized Gasoline Engines. Oil & Gas Science and Technology – Revue de L’IFP, 64(3), 431–444. https://doi.org/10.2516/ogst/2009005