Abstract:

The volumetric expanders play crucial roles in applications such as the organic Rankine cycle, compressed air energy storage, and other related systems. When facing high expansion ratios, multistage expansion becomes necessary. This paper establishes an analysis model for the Wankel expander, taking into account the operation of three working chambers, and simulates expanders connected in series. The simulation results indicate that by appropriately selecting the volume and rotational speed ratio of the expander, one can achieve a maximum power density increase of 66% and an output power increase of 47%. Across a broader range of pressure ratios, the mass flow rate of two-stage series expanders remains relatively stable. When compared to a single expander, operating at a designed or higher expansion ratio results in a power density increase of at least 15%, suggesting that series-connected expanders are well-suited for scenarios with large and fluctuating expansion ratios.

Key words: volumetric expanders, wankel expanders, multistage expansion, mathematical model

摘要：

容积式膨胀机在有机朗肯循环及压缩空气储能等系统中扮演着重要角色。尤其在面临高膨胀比的场合时，多级膨胀运行成为不可或缺的选择。本文依据三角转子膨胀机的三个工作腔的运行原理，构建了相应的模型，并针对两级串联三角转子膨胀机的运行特征及其影响因素展开了深入分析。研究结果显示，通过合理匹配膨胀机的容积与转速比例，可以实现66%的功率密度增长和47%的输出功率提升。与单级膨胀机相比，在设计的膨胀比条件下或实际膨胀比较高时，多级串联膨胀机的功率密度至少提高了15%，即多级串联膨胀机可适合大膨胀比或膨胀比波动较大的工况中。

关键词: 容积式膨胀机, 三角转子膨胀机, 多级膨胀, 数学模型