首页   按字顺浏览 期刊浏览 卷期浏览 Estimation of Nucleation Parameters from Continuous Cooling Droplet Experiments
Estimation of Nucleation Parameters from Continuous Cooling Droplet Experiments

 

作者: Fraser P. Price,   Fred Gornick,  

 

期刊: Journal of Applied Physics  (AIP Available online 1967)
卷期: Volume 38, issue 11  

页码: 4182-4186

 

ISSN:0021-8979

 

年代: 1967

 

DOI:10.1063/1.1709102

 

出版商: AIP

 

数据来源: AIP

 

摘要:

A theoretical and computational investigation has been made of the effect of temperature and of various energetic parameters upon the course of homogeneous nucleation in suspensions of droplets undergoing cooling at a constant rate. The applicable theory involves integrals, unsolvable in closed form, that were evaluated numerically. For a given size distribution of droplets, the plots of number‐fraction crystallized vs time have virtually identical shapes regardless of the cooling rate. The curves can be superposed by translation along the time axis. This superposability obtains regardless of the breadth of the size distribution. Thus, the superposability assumption tacitly invoked by early investigators in this field is justified. Furthermore, it was found that the integrations performed numerically gave, in the range of experimental interest, results within 3% of the analytical solution obtained by Burns and Turnbull by series expansion of the integrand.The pre‐exponential term in the expression for the nucleation rate is calculable for specific values of droplet size and cooling rate and is extremely sensitive to the magnitude of the energetically determined constant term appearing in the exponent. For the specific case of suspensions of polyethylene droplets a change of 10% in the constant term, necessitates a change of three orders of magnitude in the exponential.Finally, values of the interfacial energy product, &sgr;2&sgr;e, of 1.59×104and 1.50×104erg3·cm−6were calculated for polyethylene from the droplet cooling data of two independent groups of investigators.

 

点击下载:  PDF (301KB)



返 回