• Clean Technology
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• v.18 no.3
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• pp.320-324
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• 2012

In the present study, the discharge characteristics of a lithium-ion battery was evaluated to calculate the rate of heat generation under various discharge rates by mathematical modeling. The modeling and simulation of a pseudo-two dimensional ionic transport system for governing Butler-Volmer equation were carried out by using FEMLAB as a PDE (partial differential equation) solver, where the discharge rate was changed from 5 $A/m^2$ to 25 $A/m^2$. The computational results showed that the concentration of consumed solid-phase lithium at the surface of electrode was increased with increasing discharge rates. While the resulting diffusion limitation occurred shortly, it increased the rate of heat generation even more rapidly for the internal voltage to approach the cutoff voltage of the lithium-ion battery.

• Journal of the Korean Society of Propulsion Engineers
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• v.15 no.4
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• pp.35-40
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• 2011

An experimental study of the flame response in a turbulent premixed combustor has been conducted in order to investigate mechanisms for combustion instabilities in a lean premixed gas turbine combustor. A lab-scale combustor and mixing section system were fabricated to measure the flame transfer function. Measurements are made of the velocity fluctuation in the nozzle using hot wire anemometry and of the heat release fluctuation in the combustor using chemiluminescence emission. The results show that the flame transfer functions are greatly dependent on the modulation frequency as well as operating conditions such as equivalence ratio. Flame dynamics can be generalized as a function of Strouhal number which is a ratio of flame length to modulation wave length.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.04a
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• pp.430-432
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• 2011

An experimental study of the flame response in a turbulent premixed combustor has been conducted in order to investigate mechanisms for combustion instabilities in lean premixed gas turbine combustor. A lab-scale combustor and mixing section system were fabricated to measure the flame transfer function. Measurements are made of the velocity fluctuation in the nozzle using hot wire anemometry and of the heat release fluctuation in the combustor using chemiluminescence emission. The results are analyzed to determine the phase and gain of the flame transfer function as a function of the modulation frequency and operating conditions.

• Transactions of the Korean Society of Mechanical Engineers
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• v.9 no.5
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• pp.548-554
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• 1985

This research is to find a means of reducing diesel engine combustion noise with none or minimum sacrifice of engine performance by investigating the influence of Cylinder Pressure Level(CPL). For this purpose, modified Wiebe's combustion function, considering the heat release curve as a combustion of both premixed and diffusive combustion portion, was exclusively used to obtain the indicator diagram and computer coeds were developed for the numerical analysis. Following are the results of this research. (1) CPL increases almostly with lag of ignition timing increasing .alpha. and decreasing. theta.$_{d}$, but at the crank angle with the maximal efficiency, CPL is independent of .alpha. and .theta.$_{d}$ with constant value of 200 dB especially at the low frequency. (2) For the constant ignition timing, the effects of .alpha. and .theta.$_{d}$ on CPL were the most significant at the frequency of about 1KHz and 300Hz respectively. (3) For the constant value of .alpha. and .theta.$_{d}$, CPL increases linearly with load but thermal efficiency increase very rapidly with maximum value of load Q$_{T}$=30-40 MJ/Kmol, then starts to decrease slowly. (4) The most effective way of reducing combustion noise without sacrificing thermal efficiency, is to decrease .alpha.. In the case of constant .alpha., there always exists a optimum value of .theta.$_{d}$ with respect to the various compression ratio.o..atio.o..

• Korean Journal of Food Science and Technology
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• v.20 no.3
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• pp.303-309
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• 1988

The heat generation at the start-up period of an autogeneous single screw extruder was determined with various feed materials, die structure and operational conditions. The highest heat generation rate was observed with defatted soybean meal, while the lowest value was obtained with rice flour, and wheat and barley flour showed the intermediate rate. As the moisture content of the flour decreased and the screw speed increased, the electric power requirement and heat generation rate increased. The temperature at compression section increased with the decrease in the particle size. The same effect was also observed as breaker plate was installed. The optimum operation was established as the temperature profile was maintained in decreasing order of metering section, die and compression section.