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A chemisorption power generation cycle with multi-stage expansion driven by low grade heat

Lookup NU author(s): Dr Huashan Bao, Dr Zhiwei Ma, Professor Tony Roskilly

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).


Abstract

© 2017 The Authors. 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.


Publication metadata

Author(s): Bao H, Ma Z, Roskilly AP

Publication type: Article

Publication status: Published

Journal: Energy Conversion and Management

Year: 2017

Volume: 150

Pages: 956-965

Print publication date: 15/10/2017

Online publication date: 23/07/2017

Acceptance date: 02/04/2016

ISSN (print): 0196-8904

ISSN (electronic): 1879-2227

Publisher: Elsevier Ltd

URL: https://doi.org/10.1016/j.enconman.2017.07.032

DOI: 10.1016/j.enconman.2017.07.032

Data Source Location: http://dx.doi.org/10.17634/152536-2


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