卡诺电池堆积床潜热储热装置的实验和数值研究

Experimental and numerical investigation of a packed bed latent heat storage system for Carnot batteries

卡诺电池作为高效、环保、灵活且可靠的能源存储器件,且有显著的应用潜力。本工作设计了一套堆积床储热装置,并将其整合到20 kW/5 h的卡诺电池实验系统中。通过采用3种分层放置的不同材料,实现了梯级储放热。经过实验验证的二维轴对称模拟进一步揭示了相变间隔和孔隙率对梯级相变堆积床储热(CPB-TES)系统的影响。为了提高能量效率并保持卡诺电池中的压缩机和膨胀机稳定运行,研究过程中还在系统后端添加了换热器以回收CPB-TES的余热。结果表明,提高入口温度和流量能加速相变过程并提高充放电速率,但也会增加能量损失。相变间隔越小,相变材料的平台期越显著,发生相变的过程越短暂。孔隙率为0.4的堆积床相比孔隙率为0.6的堆积床,不仅储能密度有所提高,而且流体和相变材料换热也更加充分。在最小进口流量120 m^(3)/h和最高进口温度331℃的实验条件下,通过回收余热,系统的往返效率最高可达70.31%。本工作对卡诺电池中的关键装置进行深入研究,进而对整体系统进行优化,为卡诺电池高效而广泛的规模化应用提供了一定的参考。

Carnot batteries,known for their efficiency,environmental benefits,flexibility,and reliability,hold substantial potential for energy storage applications.This study focuses on a packed bed thermal energy storage(TES)system,designed and integrated into a 20 kW/5 h Carnot battery experimental setup.Stratified thermal storage was achieved through the use of three layers of different materials,facilitating cascading heat storage and release.Two-dimensional axisymmetric simulations,validated experimentally,were used to investigate the effects of phase change intervals and porosity on the cascaded packed bed thermal energy storage(CPB-TES)system.To enhance energy efficiency and ensure stable operation of compressors and expanders within the Carnot battery,a heat exchanger was implemented at the backend of the system to recover excess heat from the CPB-TES.Results indicated that while increasing the inlet temperature and flow rate accelerated phase change processes and charge-discharge rates,it also led to energy losses.Smaller phase change intervals resulted in more pronounced plateaus within the phase change material,thereby shortening the phase change duration.A porosity of 0.4 in the packed bed exhibited higher energy storage density and more efficient heat exchange between the fluid and phase change material compared to a porosity of 0.6.Under experimental conditions with a minimum inlet flow rate of 120 m^(3)/h and a maximum inlet temperature of 331℃,the round-trip efficiency of the system up to 70.31%through to heat recovery.This research offers a comprehensive analysis of critical components in Carnot batteries,driving overall system optimization and supporting the efficient and scalable application of Carnot batteries.