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Experimental study on oscillating flow steam engine in a single micro tube
Kanno, Hiroshi,Han, Youngbae,Shikazono, Naoki Elsevier 2017 Experimental thermal and fluid science Vol.81 No.-
<P><B>Abstract</B></P> <P>Oscillating flow steam engine can be a cost-effective solution for recovering work from waste heat due to its structural simplicity. In the present study, the effects of design parameters and operating conditions of oscillating flow steam engine such as tube diameter, heating section temperature, cooling section length ratio and compression ratio are experimentally investigated. The pressure variation due to boiling and condensation induces a continuous oscillating flow in a single micro tube, which can generate work using crank-piston system. The indicated work and cycle efficiency both increase as the heating section temperature and compression ratio are increased. The investigated oscillating flow steam engine achieved indicated work of 1W with the cycle efficiency of <I>η</I> =5% at <I>T</I> <SUB>heat</SUB> =230°C and <I>T</I> <SUB>cool</SUB> =80°C in a <I>D</I> =1.0mm tube.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Oscillating flow steam engine is investigated for waste heat recovery. </LI> <LI> Experimental setup for oscillating flow steam engine in a single micro tube is made. </LI> <LI> Effects of several parameters on heat engine are investigated experimentally. </LI> <LI> Current heat engine achieved 1W work and 5% efficiency between 230°C and 80°C. </LI> </UL> </P>
Liquid film thicknesses of oscillating slug flows in a capillary tube
Youn, Young Jik,Han, Youngbae,Shikazono, Naoki Elsevier 2018 INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER - Vol.124 No.-
<P><B>Abstract</B></P> <P>Liquid film thickness is an important parameter for predicting boiling and condensation heat transfer coefficients in a microscale slug flow. In the present study, liquid film thickness of oscillating slug flow in a capillary tube is experimentally investigated under adiabatic condition. Laser focus displacement meter is used to measure the initial liquid film thickness. Circular tube with inner diameter of 1 mm is used for the test tube, and water and ethanol are used as working fluids. Measurement is carried out using a capillary tube with one open end and the other connected to a stepping motor. Driving frequency is ranged from 1 to 10 Hz at equivalent slug stroke of 31.7 mm and 51.2 mm. As the frequency and equivalent slug stroke are increased, the liquid film thickness deviates from that in the steady condition and becomes thinner or thicker under flow acceleration or deceleration, respectively. The empirical correlations for the initial liquid film thickness under acceleration and deceleration conditions proposed in the previous study (Youn et al., 2015, 2016) well predict the liquid film thicknesses of the oscillating flows within 15% accuracy.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Liquid film thicknesses in oscillating micro tube slug flows are measured. </LI> <LI> LFDM technique is used to accurately measure the liquid film thickness. </LI> <LI> Under oscillating condition, the velocity and the liquid film thickness are affected by the acceleration and deceleration. </LI> <LI> Empirical correlation is proposed for the initial liquid film thickness in oscillating slug flows. </LI> </UL> </P>