STUDY ON PNEUMATIC CONVEYANCE OF COLD ENERGY USING A PHASE-CHANGE MATERIAL ENCLOSED IN SMALL SPHERICAL CAPSULES

在这项研究中，提出了一种精细化的冷能输送系统，以降低所需的泵功率，并对该系统的可行性进行了讨论。一般情况下，传统的冷能输送系统采用冷盐水直接输送冷能，特别是在冷能输入量较大的情况下，需要较大的泵浦功率。为了克服传统系统的缺陷，提出了一种利用包裹在小胶囊中的相变材料(PCM)的潜热，利用气体流动输送胶囊的改进系统，并构建了小型试验回路来测试该系统的输送性能，并与传统系统的冷能输送性能进行了比较。结果表明，在冷能输送速率相同的情况下，该系统比传统系统需要更少的泵浦功率，特别是当冷能输送速率变大时(如&gt；1 MW)。为了最小化所需的泵浦功率，还考察了胶囊的形状和大小对压降的影响。研究结果表明，采用外径与管道内径相近的大胶囊垂直输送胶囊所需的泵浦功率较小，球形胶囊比圆柱形胶囊需要较小的泵浦功率。此外，研究人员还提出了一种使胶囊内的相变材料发生振动的流态化冷冻机，以加强过冷相变材料的冻结，并考察了振动幅度和频率对冻结的影响。结果表明，将胶囊与冷却气体介质流态化的流态化床式冷冻机适合于减小小胶囊内相变材料的过冷度。

In this research, a refined cold-energy conveying system which reduces the required pump power was proposed and feasibility of the proposed system was discussed. Generally speaking, the conventional cold-energy conveying system, in which the cold-energy is directly transported by chilled brine, requires large pumping power especially when the amount of transporting cold-energy becomes large. In order to overcome the defect of conventional system, the proposed refined system utilizes the latent heat of a phasechange material (PCM) enclosed in a small capsule and the capsules are conveyed with gas flow.Small scale test loop of the proposed system was constructed to measure the conveying performances and cold-energy conveying performance of the proposed system was compared with the one of conventional system. The results snowed that, under the condition of identical cold-energy conveying rate, the proposed system requires less pumping power than the conventional one especially when the conveying rate of cold-energy becomes large (e.g. > 1 MW). In order to minimize the required pumping power, effects of shapes and sizes of the capsules on the pressure drop were also examined. The results that the pumping power required for vertical transportation of the capsules by using large capsules outer diameter of which is almost similar to the inner diameter of duct, and that spherical capsules require less pump power than cylindrical ones.In addition to these investigation, the investigators proposed a fluidized-bed-type freezer which make the PCM enclosed in a capsule vibrate to enhance freezing of supercooled PCM, and effects of amplitude and frequency of the vibration on freezing was examined. The results showed that the fluidized-bed-type freezer in which the capsules are fluidized with chilled gaseous medium is suitable for reducing supercooling of PCM enclosed in a small capsule.