Ўзбекистон республикаси фанлар академияси

 
Литература:
1.
Григорьев Б. А., Цветков Ф. Ф. Тепломассообмен: Учеб. пос. 2-е изд. –М.: МЭИ, 2005. 
2.
Zohidov R.A., Aiimova M.M., Mavjudova Sh.S. Issiqlik texnikasi: o'quv qo‘llanma // O‘zR 

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161 
OO’MTV. -T.: O‘zbekiston faylasuflari milliy jamiyatii, 2010, 312 b. 
3.
 
https://teplonositeli-pro.ru/info/osnovnye-vidy-teplonositeley/ 
4.
Филиппов В.В. Изучение процесса теплообмена в теплообменнике «труба в трубе». Метод. 
лабор. раб. -Самара: СГTУ, 2013. 23 с. 
5.
Sarit Kumar Das , Stephen U. S. Choi & Hrishikesh E. Patel (2006), Heat Transfer in Nanofluids -
A Review, Heat Transfer Engineering, 27:10, 3-19, DOI: 10.1080/01457630600904593. 
INVESTIGATION PHASE TRANSITION BEHAVIOUR OF NANOFLUIDS BY DYNAMIC 
LIGHT SCATTERING 
K.B.Egamberdiev, S.Z.Mirzaev,
 
V.N.Avdievich, T.Mustafaev, S.Telyaev
Institute of Ion-Plasm and Laser Technologies, Academy of Sciences of Uzbekistan 
Nanofluid is one of the new type of suspensions, which consists of nanoparticles and base 
fluid. When a small concentration of nanoparticles is added in the base fluid, nanofluids indicate a 
significant enhancement in the rheological and thermal properties of the base fluid [1]. Interesting 
property of nanofluids is that they have an abnormally enhanced thermal conductivity. It makes a 
stable and durable liquid for new-generation coolants and heat transfer fluids. It is assumed that the 
Brownian motion of nanoparticles in the base fluid is one of the main physical mechanisms of the 
thermal conductivity of nanofluids [2]. Nanofluids can be used to improve heat transfer efficiency in 
various systems such as heat transfer enhancement and electronic cooling systems [3]. However, the 
providing investigations on solid–liquid phase transition properties of nanofluids was limited, as a 
result, there are insufficient data for the applications of nanofluids in cold thermal energy storage 
systems, which are widely used in various 
industrial and domestic applications. 
The phase transition of nanofluids is 
interesting from the point of view of fundamental 
aspects and is used in solving a number of 
technological problems. We investigated the 
effect of SiO
2
nanoparticles 16 nanometers in size 
on 
the 
crystallization 
(or 
solidification) 
temperature 
of 
cyclohexanol. 
Nanofluids 
containing SiO
2
nanoparticles with different 
weights were prepared by two methods. In this 
case, cyclohexanol was used as a dissolution 
liquid. Nano powders were deagglomerated after 
dilution 
in 
a 
liquid. 
The 
crystallization 
temperature was measured from the dynamic light scattering method. Obtained data are indicated in 
Fig. 1. The results show that the temperature of the phase transition of nanofluids is lower than in the 
base fluid. The phase transition temperature decreases with increasing concentration of nanoparticles. 
In this case, the scattered count rate, on the contrary, increases with increasing concentration of SiO
2
nanoparticles. In Fig. 1 is indicated that solidification temperature of cyclohexanol based nanofluid 
with 32 nm SiO
2
nanoparticles decreased at range of 0%SiO2
<0.3% of nanoparticle’s concentration. 
There was a slight maximum at the 0.3% and after that solidification temperature leveled off with 
increase nanoparticle’s concentration. The transition temperature of nanofluids with 16 nm SiO
2
nanoparticles was about 2.5 
o
C lower and with 40 nm SiO
2
nanoparticles was roughly 4 
o
C lower than 
that base fluid. Tseng et al. found that the phase change temperature of Cu-water nanofluids is only 
about 1 
o
C higher than that of the deionized water [4]. The changing of transition temperature of fluids 
with adding nanoparticles probably may lead to alter the nucleation mechanism of the nanofluids.