The purpose of this study is to understand the physical and chemical characteristics of biodiesel blended fuel reformed by ultrasonic energy irradiation. To do this, a mixture of commercial diesel fuel and biodiesel was compared and analyzed according to whether or not ultrasonic energy irradiation was performed and the duration of irradiation. The results of the experiments indicate that when ultrasonic energy irradiation was performed on biodiesel blended fuel, its viscosity decreased by 37%. In the case of BD20, when ultrasonic energy irradiation was performed, its Sauter mean diameter (SMD) dropped by 12% on average. As the irradiation duration increased, the volume ratio of olefins increased up to a maximum of 2.7%, and the higher heating value increased to a maximum of 5.8%. On the contrary, the ratio of aromatics decreased by a maximum of 2.7%, and BI decreased by a maximum of 7%.
Since refrigerants applied to vehicle air conditioning systems exacerbate global warming, many studies have been conducted to supplement them. However, most studies have attempted to maximize the efficiency and minimize the environmental impact of the refrigerant, and thus, an air conditioning system without refrigerant is required. The vortex tube is a temperature separation system capable of separating air at low and high temperatures using compressed air. When applied to an air conditioning system, it is possible to construct an eco-friendly system that does not use a refrigerant. In this paper, various temperature changes and characteristics of a vortex tube were identified and applied to an air conditioning system simulation device. Additionally, an air conditioning system simulation device using indirect heat exchange and direct heat exchange methods was constructed to test the low-temperature air flow rate (yc), according to the temperature and pressure. As a result of the experiment, the temperature of the indirect heat exchange method was found to be higher than the direct heat exchange method, but the direct heat exchange method had low flow resistance. As a result, the direct heat exchange method can easily control the temperature according to the pressure and the low-temperature air flow rate (yc). Therefore, it was judged that the direct heat exchange method is more feasible for use in air conditioning systems than the indirect heat exchange method.
Abstract. As fossil fuel depletion and environmental pollution
problems are becoming increasingly more serious, interest in the efficient
use of natural resources and alternative energy is rapidly growing. In
particular, interest in fuels stored as high-pressure gases such as natural
gas and hydrogen is also rising. Ultrasonic waves show various received
signals according to characteristics such as density of the medium and
acoustic impedance. An experimental study on the detection of the
micro-leakage of fuel stored as high-pressure gas was conducted based on the
characteristics of ultrasonic waves. First, an ultrasonic sensor was
manufactured by selecting the matching layer with consideration of the
acoustic impedance. In the experiment, a mass flow controller (MFC) was
attached to a perforated hole in the fabricated chamber to generate
micro-leakage, and the signal from the receiving ultrasonic sensor was then
collected. The envelope signal of the received ultrasonic sensor signal was
analyzed through the Gaussian distribution method. The temperature inside
the chamber and the received voltage decreased according to a similar trend
and showed a nonlinear result. However, the phase of the received ultrasonic
sensor signal showed a relatively linear result according to the internal
pressure change. Micro-leakage could not be detected with only the received
voltage seen by the ultrasonic sensor. Therefore, the phase shift of the
receiving ultrasonic sensor can be used to detect micro-leakage in a
high-pressure gas tank.
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