Abstract:

To improve the heat and mass transfer of the sorption thermal battery (STB) for a higher energy/power density of STB, the strategy of tube-free-evaporation is proposed, and then verified by the theoretical analysis. Adopting the proposed strategy, a 30 kWh STB is established. The result demonstrates that the proposed strategy can reduce the thermal resistance of the conventional evaporator with tubes by 94.9% and increases the sorption-evaporation rate of the STB by 24.2%. Thus, the STB employing the proposed tube-free-evaporator can supply the thermal energy with 3℃ higher temperature over the STB adopting the evaporator with tubes, confirming the effectiveness of the strategy in facilitating the heat and mass transfer of STB. Meanwhile, it is also found that increasing desorption temperature and decreasing condensation pressure can also promote the energy/power density of the STB. With the desorption temperature of 170℃ and condensation pressure of 7.5 kPa, the energy density and power density of the designed STB have reached 113.21 Wh/kg and 149.45 W/kg, respectively. More importantly, the supplied hot water temperature and the hot water flow have reached 55℃ and 1980.2 L/h, which demonstrates the feasibility of the designed STB on supplying hot water to multi-users or supplying hot water to single users for longer duration. So, the proposed tube-free-evaporation is expected to be enlightening in the future scalable deployment of STB with a higher energy/power density.

Key words: tube-free-evaporation, sorption thermal battery, hot water supply, power density, heat and mass transfer

摘要：

为改善吸附热池的传热传质性能以提高吸附热池的能量/功率密度，提出无管束蒸发换热强化策略，通过理论仿真分析了该策略的有效性并建立了储热容量为30 kWh的吸附热池系统。研究结果表明：与有管束蒸发器相比，所述无管束蒸发器的热阻减小了94.9%，吸附-蒸发速率提高了24.2%，因此，与基于有管束蒸发器的吸附热池相比，基于无管束蒸发换热强化策略的吸附热池的平均供热温度提高了3℃，充分证明了无管束蒸发策略对提升吸附热池传热传质性能的有效性。同时，该研究也表明，提高脱附温度和降低冷凝压力也可以有效提高吸附热池的能量/功率密度，从而使吸附热池获得更好的供热性能，当吸附热池的脱附温度升高到170℃、冷凝压力降低到7.5 kPa时，吸附热池的能量密度和功率密度分别达到了113.21 Wh/kg和149.45 W/kg，供热温度和制热水能力分别达到了55℃和1980.2 L/h，验证了所设计吸附热池系统向多用户同时供热或向单用户长时间供热的能力，为提高未来吸附热池的能量/功率密度，实现大规模储热提供了理论和实验基础。

关键词: 无管束蒸发, 吸附热池, 供热, 功率密度, 传热传质