%0 Journal Article
%T Effect of Impeller Agitation on Preparation of Tetra-n-Butyl Ammonium Bromide Semiclathrate Hydrate Slurries
%A Shunsuke Hashimoto
%A Hiroyuki Ito
%A Kazunari Ohgaki
%A Yoshiro Inoue
%J International Journal of Chemical Engineering
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/856120
%X The slurries-containing tetra-n-butyl ammonium bromide (TBAB) solution and its semiclathrate hydrate have attracted a lot of interest as latent heat transport media. These hydrate slurries contain some microparticles of crystal, and the size and shape of these hydrate particles could affect the mobility of slurries. Hence, it is essential to investigate the efficient hydrate-slurry preparation methods and the effect of hydrate particles on the fluid property of slurries for the application to latent heat transport media. In the present study, the effect of agitation on particle size distribution and aggregation of particles was studied to prepare easily flowing TBAB hydrate slurries that were suitable for fluid transport. First of all, the effects of impeller rotational speed and impeller type on the particle size and frequency of aggregation were investigated. The results suggested that the particle size distribution and the frequency of particle aggregation are strongly affected by the intensity of shear rate and its uniformity, which was controllable with impeller type and its rotation speed. 1. Introduction Recently, a large-scale district (regional) cooling system has attracted attention of many researchers because it works on saving energy and global sustainability due to its high performance of utilization of exhausted heat from large plants or factories [1]. In such system, the pumping energy loss due to the transportation of heat media is not small. To solve this problem, a high-density heat transportation system involving slurries with phase change materials (hereafter, PCM) having latent heat has been developed, for example, ice/water slurries [2]. The utilization of such PCM slurries can reduce flow rate of heat media, since latent heat of some materials is much larger than sensible heat. Fukushima et al. [3] reported the ability of slurries-containing tetra-n-butyl ammonium bromide (hereafter, TBAB) semiclathrate hydrate and its solution as latent-heat transport media, which was more favorable than ice/water system because they can be operated at relatively high temperature (ca. 285£¿K) and atmospheric pressure. Unlike ordinary gas hydrates, in these semiclathrate hydrates, the quaternary ammonium cation and anion are incorporated with the hydrogen bonds of water molecules to construct the hydrate cage [4]. In addition, four butyl groups are one-by-one encaged with a large cage separately in this semiclathrate system. There are various reports about the crystal structure and the role of bromine for the TBAB hydrates [4, 5]. The hydration
%U http://www.hindawi.com/journals/ijce/2012/856120/