Wall impact on efficiency of packed-bed thermocline thermal energy storage system

Numerical analysis of demolition waste‐based thermal energy storage system for concentrated solar power plants

“…Maximum temperature difference was seen at higher fluid velocity as a result of higher Reynolds number. Moreover, Xie et al 39 reported that temperature difference between solid sphere and surrounding HTF increases with Biot number. In this study, Biot number seen in Table 4 also increases with fluid flow rate and exceeds 0.1 at a flow rate of 200 kgh À1 .…”

“…As seen in Figure 5, maximum discharging efficiency (η Dis :76.0%) is observed at ṁ: 100 kgh À1 when flow regime is still laminar (Re p < 10), with higher stratification levels and lower heat loss. According to the Xie et al, 39 efficiency is affected from HTF flow rate and heat loss from tank wall to the surroundings. Similarly, Esence et al 47 stated that heat loss reduces the overall efficiency of the packed-bed TES system.…”

“…On the contrary to charging process, during the discharging process cold HTF is fed to the storage tank from bottom of the storage tank and hot HTF leaves from top and sent to the power block to recover heat. Cut-off temperatures are 510 C for charging 345 C for discharging which are the most common and useful temperature ranges in CSP plants to generate superheated steam (16,[37][38][39] ).…”

Optimized flow distributor for stabilized thermal stratification in a single-medium thermocline storage tank: A numerical and experimental study

“…A thermal stratification zone with temperature gradient, the thermocline, exists between hot and cold HTFs. Besides the heat loss from the storage tank to the ambient [9], the overall performance of the thermocline storage tank depends largely on the level of thermal stratification [10]. To achieve a highly-efficient charging/discharging operation, the thermocline decay (de-stratification) should be reduced to the least possible extent with a small volume occupied by this temperature transition zone [11].…”

Experimental and numerical study on the thermocline behavior of packed-bed storage tank with sensible fillers

“…Hoffmann et al [15,30] reported that the heat losses would lead to the unstable thermocline, reduced output power, and decreased outlet temperature. Xie et al [31] have developed adapted transient models to systematically explore the wall impact on the dynamic thermocline behavior of the SHTPB tanks by including the wall and insulation heat capacity in the governing equations. The most influencing factors have also been identified to provide useful design guidelines.…”