[institut] Seminar u ponedeljak 23.04.2012.

[Dr. Dragan D. Markushev]

Postovane koleginice i kolege,

pozivam vas da u ponedeljak 23.04.2012. godine u sali biblioteke 
Instituta za
fiziku, sa pocetkom u 12.00 prisustvujete seminaru

“Acoustic nonlinearities in thermoacoustic refrigerators driven by 
loudspeakers”

koji ce odrzati

Dr. Li Fan
Associate Professor
Institute of Acoustics
Nanjing University
Nanjing, China

ABSTRACT

"Thermoacoustic refrigerators have been regarded as a type of 
refrigeration method with great potential in virtue of no pollution and 
long lifetime. However, the power and efficiency of the type of 
refrigerators must be further increased in order to satisfy the 
requirement of the practical application. The equivalent circuit models 
of thermoacoustic refrigerators driven by the current and voltage are 
used to optimize the performances based on the linear theory. 
Furthermore, two important acoustic nonlinear effects in thermoacoustic 
refrigerators are studied. The first is the nonlinear effect induced by 
the acoustic source, i.e., the loudspeaker, which is dominated by two 
nonlinear parameters. The nonlinearity of the magnetic induction 
intensity in the magnetic gap only changes the amplitudes of the 
acoustic output power and electroacoustic transfer efficiency of the 
loudspeaker, and the nonlinearity of the vibration component can also 
change the resonance frequency of the coupling system composed of the 
loudspeaker and thermoacoustic resonance pipe. The second nonlinear 
effect is caused by the thermoacoustic stacks. Based on the experimental 
results, a theory model of the stack in high-intensity acoustic field is 
set up and the influences of the structure, porosity, length of the 
stack, operating frequency and so on are evaluated."

BIOSKETCH

Dr. Fan received B.S. and Ph.D. degrees in acoustics from Institute of 
Acoustics, Nanjing University, Nanjing, China, in 2002 and 2007, 
respectively. Since then he has been with the Lab of Modern Acoustics, 
Institute of Acoustics of Nanjing University, where he focuses on the 
researches of thermoacoustic refrigerations and SAW sensors. Now he is 
an Associate Professor of School of Physics in Nanjing University.

Srdacan pozdrav

Dragan D. Markushev

-- 
Dr. Dragan D. MARKUSHEV
Senior Research Associate
Laboratory for Atomic, Molecular
and Laser Spectroscopy
Institute of Physics Belgrade
Pregrevica 118,
11080 Belgrade, SERBIA
phone: +381113713158
fax: +381113162190
http://www.ipb.ac.rs/