Characteristics of Plate-Fin Heat Exchanger with Phase Change Material

潜热聚变能量系统是有用的，因为它们能够连续地向温度较低的流体提供热能，即使温度较高的流体的热量供应随着时间而变化。本文对相变材料板翅式换热器进行了研究。目前的换热器由310根边长9.5 mm、厚度0.5 mm、长度300 mm的铜方管组成，是一种单程横流换热器，两种流体(空气)不混合。采用熔融温度为28.0℃的正十八烷作为相变材料。154根管内填充2.13公斤的PCM。进行了三种实验，测量了进、出口温度和相变材料内的温度。在第一次实验中，获得了稳态下的效率和总的换热系数。板翅片使效率提高了约10%。通过对稳态三维导热的计算，得到了空气的尺寸、热物性和换热系数等参数对总换热系数的影响。在第二个实验中，由于停止了较高温度的气流，低温空气的出口温度保持在恒温90-150分钟。在第三个实验中，温度较高的空气以等间隔间歇流动。流速均为400 1/min，进风温度分别为70℃和10℃，周期为2小时。低温空气的出口温度在20℃和正负2.5℃之间。上述瞬变和周期性实验表明，目前的相变换热器具有良好的潜热蓄热特性。

Latent heat-of-fusion energy systems are useful, because they are able to supply continuously the thermal energy to the lower-temperature fluid even when the supply of heat from the higher-temperature fluid varies with time. In the present report a plate-fin heat exchanger with a phase change material (PCM) was studied. The present heat exchanger, which was made with 310 copper square-tubes with 9.5 mm sides, 0.5 mm thickness, and 300 mm length, was a single-pass cross-flow type, both fluids (air) unmixed. The n-octadecane, of which the fusion temperature is 28.0 C, was used as the PCM. The 2.13 kg PCM was filled in the 154 tubes. three kinds of experiments were carried out and the inlet and outlet temperatures and the temperatures in the PCM were measured. In the first experiments, the effectiveness and the overall heat-transfer coefficient were obtained at steady states. The plate-fin improved the effectiveness by about 10 %. By the calculations of steady three-dimensional heat conduction, the effects of the parameters, --- dimensions, thermal properties, and heat transfer coefficients of air ---, on the overall heat-transfer coefficients were obtained clearly. In the second experiments, since the higher-temperature air-flow was stoped, the outlet temperatures of the lower-temperature air were maintained at the constant temperatures for 90-150 minutes. In the third experiments, the higher-temperature air was flowed intermittently with an equal interval. The flow rates were equally 400 1/min, and the inlet temperatures of air were 70 C and 10 C, and the period was 2 hours. The outlet temperature of the lower-temperature air was between 20 C <plus-minus> 2.5 C. The above transient and periodical experiments showed that the present heat exchanger with PCM had useful characters of latent heat storagf