TBAB包络化合物浆的管内流动和传热特性研究
文献类型：学位论文
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| 作者 | 肖睿 |
| 学位类别 | 博士 |
| 答辩日期 | 2008-06-02 |
| 授予单位 | 中国科学院广州能源研究所 |
| 授予地点 | 广州能源研究所 |
| 导师 | 冯自平 |
| 关键词 | 四丁基溴化铵 包络化合物 潜热输送 流动 传热 |
| 其他题名 | Study on Flow and Heat Transfer Characteristics of TBAB Clathrate Hydrate Slurry in Pipes |
| 中文摘要 | The Tetra-n-Butyl-Ammonium Bromide (TBAB) Clathrate Hydrate Slurry (CHS) is one kind of solid-liquid suspension slurry, which is produced from TBAB aqueous solution in the temperature 0-12 ℃ under normal atmosphere. It can be used as a secondary refrigerant for high-density latent heat transportation in central air conditioning and district cooling, etc. CHS has good fluidity and so can be transferred conveniently by pumps and pipes like normal liquid. Because phase change happens between solid and liquid, the density of cold transportation of CHS is much higher than that of the cold water under the same temperature differences, then the circulating flux of refrigerant decreases dramatically, which results in the decrease of pump power consumptions, so the energy saving can be achieved. Firstly, based on the current researches throughout the world, the comprehensive thermophysical properties of TBAB and CHS have been obtained through some experimental supplements. Secondly, the general constitutive relationship of non-Newtonian fluid and several classical rheological models have been introduced. Then, the flow and heat transfer about CHS in the horizontal pipes have been studied through experiments. Data were obtained under conditions of type A or type B, laminar or turbulent, pipes with different diameter, and constant heat fluxs, etc. At last, the theoretic models of flow and heat transfer in the horizontal pipes have been established and simulated, and the results were compared between calculations and experiments. Based on the experimental data of laminar flows, the CHS of both type A and type B are confirmed as Bingham fluid when solid fraction χ < 30%. When χ >30%, however, it is no longer true because the Herschel-Bulkley rheological characteristics prevail gradually. The relationship between plastic viscosity η and solid fraction χ is verified by experimental data, so is done between yield stress τ0 and χ. In the flow experiments, the flow resistance was investigated under the conditions of constant solid fractions and constant flow velocities, respectively. A region of weakened flow resistance at constant solid fractions and a phenomenon of relaminarization at constant flow velocities were observed. Except the region of transition flow, the flow resistance increases monotonically with the solid fraction χ in the regions of both laminar and turbulent flow under the constant flow velocities. By and large, the relationship between the critical Reynolds number ReMc and solid fraction χ shows as a monotone increasing function, in which ReMc is defined according to Metzner-Reed Reynolds number ReM. At last, the logarithmic plot between the Fanning resistance coefficient f and the universal Reynolds ReM was obtained accoding to experimental data. From which the relationship of f•ReM =16 was confirmed for CHS in the region of laminar flow, which has the same form with the classical Newtonian fluids. And in the region of turbulent flow, the same correlation between f and ReM was fitted for CHS of the Type A and Type B. In the convectional heat transfer experiments, the thermal boundary conditions of constant heat flux were imposed on. The convectional heat transfer coefficient was investigated under the conditions of constant solid fractions (i.e. constant Prandtl number Pr) and constant flow velocities, respectively. A region of weakened heat transfer coefficient at constant solid fractions, similar with the region of weakened flow resistance in flow experiments, was observed. Other than in the region of transition flow, the convectional heat transfer coefficient α increases monotonically with the solid fraction χ in the regions of both laminar and turbulent flow under the constant flow velocities. At last, the correlations of Nusselt number Nu for both type A and type B were fitted according to the experimental data in the regions of laminar flow and turbulent flow, respectively. These correlations were compared with experimental results and show a maxmum error equal to ±20%. Lastly, the analytical models of flow and convectional heat transfer in the horizontal pipes were established and simulated. The model of laminar flow is based on the theoretics of Bingham fluid, and the model of turbulent flow is derived from the RNG k-ε turbulent theoretics. Based on the flow models mentioned above, the convectional heat transfer model was founded through introducing the technique of Enthalpy-Porosity, which is used to describe the effects of phase change. Through the comparisons between calculations and experiments, it was found that the flow resistance was overestimated, while the convectional heat transfer coefficient was underestimated consistently by the analytical models. |
| 语种 | 中文 |
| 公开日期 | 2011-07-10 ; 2011-07-15 |
| 页码 | 142 |
| 源URL | [http://ir.giec.ac.cn/handle/344007/3997]  |
| 专题 | 中国科学院广州能源研究所 |
| 推荐引用方式 GB/T 7714 | 肖睿. TBAB包络化合物浆的管内流动和传热特性研究, Study on Flow and Heat Transfer Characteristics of TBAB Clathrate Hydrate Slurry in Pipes[D]. 广州能源研究所. 中国科学院广州能源研究所. 2008. |
入库方式： OAI收割
来源：广州能源研究所
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