用于海水养殖的管壳式梯级相变蓄热装置内部传热特性的数值模拟研究

Numerical simulation of internal heat transfer characteristics in a shell and tube cascade phase change heat storage device used in mariculture

为了解决海水养殖中太阳能不连续、不稳定的蓄热问题,本文设计了可用于海水养殖行业的高效梯级相变蓄热器模型,并对其内部传热特性进行了数值模拟研究,分别对同一工况下每级PCM(PCM1、PCM2、PCM3)内部上中下三部分位置的传热特性进行了分析和讨论,同时还探究了梯级相变蓄热装置中每级PCM内相同位置的传热特性差异。结果表明:管壳式梯级相变蓄热装置在充热前期内部传热以热传导为主导,中后期以自然对流为主导;PCM上中下三部分都有较显著的传热差异,PCM3熔化速度较PCM2、PCM1快,PCM下部与中部之间的对流传热是影响换热器整体相变速率的关键。本文建立的管壳式梯级相变蓄热模型可为高效梯级相变蓄放热装置的结构设计提供依据,以推动高效梯级相变蓄热技术在海水养殖等行业的大规模应用。

An efficient cascade thermal energy storage with phase change materials is designed for mariculture industry in order to solve the problem of solar energy discontinuity and instability in mariculture.The numerical simulation of the heat transfer characteristics in the system is carried out,and the heat transfer characteristics of the upper,middle and lower parts of phase change materials(PCM)are discussed at each stage under the same working condition.At the same time,the difference in heat transfer characteristics in the same position of each PCM is also explored in the cascade thermal energy storage.The results showed that the heat conduction is the dominant factor in the early stage of heat transfer,and the convection is the dominant factor in the middle and later stages.There were significant heat transfer differences among the upper,middle and lower parts in each PCM,with the faster melting speed at monitoring point PCM3 than that at PCM2 and PCM1.The convective heat transfer between the bottom and the middle parts in PCM was found to be the key affecting the overall phase change rate of the heat exchanger.The findings indicated that the model here provided design basis for the structure of high-efficiency cascade phase-change heat storage and release device,and that promoted the large-scale application of high-efficiency cascade phase-change heat storage technology in mariculture and other industries.