Widya Wijayanti

3D Numerical and Experimental Study on Paraffin Wax Melting in Thermal Storage for the Nozzle-and-Shell, Tube-and-Shell, and Reducer-and-Shell Models

Paraffin melting experienced in the nozzle-and-shell, tube-and-shell, and reducer-and-shell models in thermal storage with 3D numerical and experimental approach has been studied. The numerical study aims to evaluate the melting process and discover temperature distribution, liquid-solid interface, liquid fraction, and the average surface Nusselt number, while the aim of this experimental study is to determine the distribution of melting temperature. The comparison of temperature distribution between the numerical approach and experimental one indicates a good agreement. The comparison result between the three models shows that the melting process of the nozzle-and-shell model is the best, followed by tube-and-shell and reducer-and-shell models, successively. To finish the melting process, the time required is 6130 s for the nozzle-and-shell model, while tube-and-shell model requires 8210 s and reducer-and-shell model requires 12280 s.

The effect of swirl vanes on the visualization and temperature distribution of co-flow diffusion flame

Swirl vanes are a flame retardant instrument that promotes the formation of zone of recirculation to improve the mixing of reactants and flame stabilization. The swirl vanes are often used in a variety of burner to improve the performance and efficiency of the burner. In the present study, we investigate experimentally the effect of different shape of swirl vanes on flame visualization and temperature distribution of diffusion flames on co-flow burner. Three types of swirl vanes are twist, curved and skewed types. In this co-flow burner configuration, the flow rate of fuel was varied from 1.32 to 15.92 m./s, while the flow rate of air was varied from 0.08 to 0.3 m/s. Temperature of the flame was measured at 12 points around the flame to obtain the temperature distribution of the flame. The results show that the skewed swirl produced a highest flame shape and uniform temperature distribution compared to others swirl. The differences tendency between three types of swirl vanes on the visualization of the co...

A Great Achievement of Calculated and Experimental Results of Char Kinetic Rate in Woody Mahogany Pyrolysis

In the pyrolysis process, it is needed to know the value of k (rate costant) to know the rate of reaction that occurs. It is needed to calculate k caused by T effect due to the reason that it is extremely difficult experimentally to find rate constants. The pyrolysis process was carried out for three hours with the minimum condition of Oxygen using mahogany wood. It was used the pyrolysis temperature variations of 250°C to 800°C. The results showed the increasing temperature and decreasing mass of char as long as the process to obtain, the kinetic rate of char k . We used two calculation approaches method to find the calc ulated k . Fristly, it used the total kinetic rate model equation with the equation k T = 60.3 e -2028.4/T and the second one, it was used the local kinetic rate model. In the local kinetic rate approached, it was divided the 3 temperature ranges; k 1 in the range of 28°C - 250°C was k 1 = 539.1 e -2907.3/T , k 2 in the range of 250°C to 500°C was k 2 = 27.11 e -1424/T ; and k 3 in the range of at range 500°C to 800°C was k 3 = 572.4 e -4549.2/T . Then, by using the found k values, it was found the great achievement results that the decreasing mass of char in the calculation was coincide with the experimental results. It was used both kinetic rate methods depending on the required energy was needed in the pyrolysis process; at low pyrolysis temperatures, the appropriate kinetic rate model was a local kinetic rate model, and for pyrolysis at high temperatures of 600°C to 800°C, the accurate kinetic rate model was the total kinetic rate model.

Increased Melting Heat Transfer in the Latent Heat Energy Storage from the Tube-and-Shell Model to the Combine-and-Shell Model

The melting of paraffin in thermal storage tube-and-shell and combine-and-shell models was conducted with the numerical research aim of decreasing the charge time through changing the shape of the tube into combining form. The results discussed are temperature contour, liquid-solid interface contour, temperature distribution, liquid fraction, and the average Nusselt number. The results show that the charge time in the tube-and-shell model is 2000 s, while the combine-and-shell model is 1200 s, meaning an overall decrease in charge time in the combine-and-shell model by 40% when compared to that of the tube-and-shell model.

Study on propane-butane gas storage by hydrate technology

Different technology has been applied to store and transport gas fuel. In this work the storage of gas mixture of propane-butane by hydrate technology was studied. The investigation was done on the effect of crystallizer rotation speed on the formation of propane-butane hydrate. The hydrates were formed using crystallizer with rotation speed of 100, 200, and 300 rpm. The formation of gas hydrates was done at initial pressure of 3 bar and temperature of 274K. The results indicated that the higher rotation speed was found to increase the formation rate of propane-butane hydrate and improve the hydrates stability.