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Nano- refrigerant heat transfer characteristics of pool boiling

Author: ZhuangDaWei
Tutor: GuJianMing；DingGuoLiang
School: Shanghai Jiaotong University
Course: Refrigeration and Cryogenic Engineering
Keywords: Nanoparticles Nucleate pool boiling Heat Lubricating oil
CLC: TB64
Type: Master's thesis
Year: 2011
Downloads: 64
Quote: 0
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Abstract

As a new refrigerant, the refrigerant nanopowder with conventional refrigerant composed of nano gaining more and more attention. Studies have shown that the existing refrigerant nm than the conventional refrigerant better thermal performance; given thermal conductivity properties of the phase change heat transfer correlation with the expected nano refrigerant higher than conventional refrigerant boiling heat transfer performance. Therefore it is necessary for nano pool boiling heat transfer characteristics of refrigerant studied. In this paper, a combination of experimental and theoretical methods, the nano-refrigerant pool boiling heat transfer characteristics were studied. The main research work and conclusions are as follows: (a) the design and construction of this nano pool boiling heat transfer of refrigerant test bench, test based on spherical nanoparticles and carbon nanotubes nano refrigerant oil pool boiling heat transfer characteristics of nuclear test surfactant of nano nano refrigerant and refrigerant oil nucleate pool boiling of; (2) by scanning electron microscopy (SEM) analysis of spherical nanoparticles and nanotubes of the heating surface characteristics; raised nm scale solid-phase component and the non-additive component synergy phase transition phase transitions nucleate pool boiling heat transfer fluid quantitative forecasting methods, based on the method established based on the spherical nanoparticles and carbon nanotubes refrigerant oil nano-nuclear states pool correlations of boiling heat; through the introduction of surfactant impact factor, established under the action of the surfactant nano nano refrigerant and refrigerant oil nucleate pool boiling heat transfer correlations calculated. (3) on the nano pool boiling heat transfer characteristics of refrigerant research shows: nanopowder reinforced nano refrigerant oil nucleate pool boiling heat transfer, high thermal conductivity and small diameter spherical nanoparticles smaller in diameter and length of the large more significant strengthening effect of carbon nanotubes. Nucleate pool boiling heat transfer enhancement surface is mainly due to the formation of nanoscale porous layer, resulting in the heating surface and gasification core hole density increased density; spherical particle size and concentration of nanoparticles, carbon nanotubes geometry and concentration affect the structure of the porous layer, thereby affecting nucleate pool boiling heat transfer on the strengthening effect. In addition to the high surfactant concentration conditions, the surfactant enhanced nano nano refrigerant or refrigerant oil nucleate pool boiling heat transfer, with the strengthening effect of its concentration first increases and then decreases, the peak corresponding to the surface-active With the concentration of oil concentration nm increases; different types of heat transfer enhancement level of surfactant in the reverse order to their molecular size, and with the concentration of nanoparticles, nano oil concentration, the decrease of the heat flux. Established based on spherical nanoparticles and nanotubes nucleate refrigerant oil nano Boiling heat transfer correlations of different types and size suitable for spherical nanoparticles, carbon nanotubes of different geometries, and has a good prediction accuracy . Established under the action of the surfactant nano nano refrigerant and refrigerant oil nucleate pool boiling heat transfer correlation calculations can accurately predict surfactants on nucleate pool boiling heat transfer.

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