A chemisorption power generation cycle with multi-stage expansion driven by low grade heat
A chemisorption power generation cycle with multi-stage expansion driven by low grade heat
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DOI：
10.1016/j.enconman.2017.07.032
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发表时间：
2017-10
影响因子：
10.4
通讯作者：
Huashan Bao;Zhiwei Ma;A. Roskilly
中科院分区：
文献类型：
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作者：
Huashan Bao;Zhiwei Ma;A. Roskilly
由于两个盐吸附剂反应器之间存在巨大的压差，低温热驱动的氨基化学吸附循环具有巨大的发电潜力。然而，氨作为湿流体的固有特性以及化学吸附循环与膨胀装置之间的难以匹配阻碍了这种发电系统的发展，也增加了实际实施的难度。为了探索这项技术的最大效益，本工作提出并研究了一种新的吸收发电循环，适用于多次膨胀。多次膨胀与再热工艺相结合的应用旨在克服氨是湿流体的限制，并充分利用化学吸附可以提供的巨大压差用于发电，从而提高能源效率。本文不仅从理论热力学的角度，而且考虑了实际的影响因素，对溴化钠-氯化锰、氯化锶-氯化锰和溴化钠-氯化锶三种典型吸收盐对的多重膨胀吸收式发电循环的性能进行了研究，以期为真实的系统设计提供更好的理解和启示。采用溴化钠-氯化锰和溴化钠-氯化锶对的多次膨胀再吸收发电，在热源温度为30 °C ~ 150 °C时，可获得100-600 kJ/kg（氨）的功输出;采用氯化锶-氯化锰对的多次膨胀比采用其他两对的多次膨胀每级平均功输出高。在平衡压降设定为2 bar且热源温度在80-150 °C范围内的更实际的情况下，当实施2-4次膨胀时，循环能量效率可以达到0.06-0.15。在相同的热条件下，这样的效率大约是卡诺效率的27-62%。
Ammonia-based chemisorption cycle driven by low grade heat exhibits vast potential for power generation because there exists huge pressure difference between the two salt-adsorbent-filled reactors. However, the intrinsic feature of ammonia as a wet fluid and the difficult match between chemisorption cycle and expansion device impede the development of such a power generation system and also increase the difficulty of practical implementation. To explore maximum benefits of this technology, the present work has proposed and studied a new resorption power generation cycle that applies multiple expansion. The application of multiple expansion integrated with reheating processes aims to overcome the limitation of the ammonia being wet fluid and fully harness the huge pressure difference that chemisorption can offer for power generation, leading to the improvement of energy efficiency. The performance of the proposed multiple expansion resorption power generation cycle using three typical resorption salt pairs, including sodium bromide – manganese chloride, strontium chloride – manganese chloride and sodium bromide – strontium chloride, have been investigated not just based on theoretical thermodynamics but also with the consideration of practical factors to obtain better understanding and more insights for a real system design. The multiple expansion resorption power generation using sodium bromide – manganese chloride and sodium bromide – strontium chloride pairs can achieve 100–600 kJ/kg (ammonia) work output when heat source temperature is from 30 °C to 150 °C; the multiple expansion using strontium chloride – manganese chloride pair has higher average work output per one expansion stage than that using the other two pairs. The cyclic energy efficiency can be achieved as 0.06–0.15 when implementing 2–4 expansions in a more practical scenario where the equilibrium pressure drop is set to 2 bar and the heat source temperature is in the range of 80–150 °C. Such efficiencies are circa 27–62% of Carnot efficiency under the same thermal conditions.