University of Technology-Iraq
Engineering and Technology Journal
1681-6900
30
10
2012
06
01
An Experimental Study for the Effect of Vertical Forced Vibration on Pool Boiling Heat Transfer Coefficient
1662
1676
56997
10.30684/etj.30.10.1
EN
Zena
K. Kadhim
Ahmed
A. Mohamed
Sarah
Ali Abed
Journal Article
2012
06
01
In this research, an experimental study for the effect of forced vibrations on<br /> pool boiling heat transfer coefficient has been made in a glass of chamber<br /> cylindrical shape (75 mm bore and 300 mm length) and an electrical heater inside it<br /> (12 mm diameter and 80 mm length) to heat the distilled water at different values<br /> of heat flux (27.521 kW/m2-53.08 kW/m2) utilized to perform this work. The<br /> experimental study is carried out at a range of frequencies (2-40 Hz) and at a range<br /> of amplitude (1.8-3.5 mm).<br /> The result obtained showed that the pool boiling heat transfer coefficient is<br /> increasing with increasing the vibration frequency within a range of (2-14 Hz),<br /> compared with that heat transfer without frequency. And, the maximum<br /> enhancement ratio is about 250% at 5 Hz and q"=27.521 kW/m2, 231% at 6 Hz and<br /> q"=36.727 kW/m2, 181% at 6 Hz and q"=41.83 kW/m2 and 93% at 8 Hz and<br /> q"=53.08 kW/m2. In general, it is found that the difference in the temperature has<br /> been maintained at the highest value of vibration frequency range of (14-40 Hz),<br /> and the value of heat transfer coefficient is significantly increasing with increasing<br /> the vibration Reynolds number (Rev).<br /> The effect of vibration frequency has improved not only the boiling heat<br /> transfer coefficient, but also led to improve the amount of heat drawn by the<br /> cooling water (condensation) by increasing the amount of falling drops.<br /> The following empirical relations have been obtained between the experimental<br /> heat transfer coefficient with vibration (hv) and some of important parameters, such<br /> as excess temperature (ΔTexsses) in oC, input heat flux (q") in (W/m2), and vibration<br /> frequency (f) in Hz:<br /> hv = 0.246912 × f0.16534 × ΔT-0.92429 × q"1.0727 nd, the second correlation is (hv)<br /> with Reynolds vibration effect (Rev) and input heat flux (q") in<br /> (kW/m2)hv=499.747×Rev0.3576×q"-2.14
https://etj.uotechnology.edu.iq/article_56997_c149e3ace1a78bb5b4b192aed755f05b.pdf