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ABSTRACT
In recent years, nano-magnetic fluid and magnetic field technology have been
widely applied in many fields with their fast development. The nano-magnetic fluid
has became a hot topic in strengthening heat and mass transfer because of its finite size
effects, surface effects and magnetic effects under the magnetic field. As new mediums
for strengthening heat and mass transfer, effects of nano-magnetic fluid and magnetic
fields have been proved. These practices provide the possibility for the introduction of
the nano-magnetic fluid and magnetic fields to strengthen the ammonia-water
absorption.
The COP of the ammonia absorption refrigeration system is closely related to the
mass transfer of the absorber. To improve the mass transfer in the absorber, an
experimental system of ammonia bubble absorption with rotating magnetic field was
designed and built up. The experiments of the NH3/H2O bubble absorption with
rotating magnetic field and Fe3O4 nano-magnetic as strengthened mediums were
carried out to find the influences of rotating magnetic field and Fe3O4 nano-magnetic.
Besides, a mathematical description was established and the mechanism of
strengthening absorption process was analyzed.
The main research work and the conclusions are as follows:
1. Theoretical analysis is carried out about the ammonia bubble absorption. The
bubble absorption is divided into two processes; one is bubble generation process and
the other is bubble rise process. Both of the two processes are stress analyzed and the
mathematical descriptions are established. The strengthening mechanisms of each
factor in the mathematical description are summarized and analyzed and the impacts of
the strengthening methods on each factor in this paper in the mathematical description
are analyzed.
2. An ammonia bubble absorption system with rotating magnetic field is built up.
Process of the ammonia bubble absorption experimental system with rotating magnetic
field, the experimental apparatus, the experimental test components, the data
acquisition system and system errors are introduced and analyzed. The method based
on the real gas equation of state in the isolated system to calculate the absorption effect
is proposed.
3. The experiments of the optimum time length and the best nano-magnetic fluid