The heat pump operated single-stage humidification-dehumidification desalination system, configured with a subcooler and a heat regenerator, has been proven highly effective in improving both freshwater productivity and energy efficiency. To investigate the potential benefits of increasing the number of humidification stages, this paper presents a heat pump operated two-stage humidification-dehumidification desalination system by adding a pre-humidifier. Subcooler and condenser of the heat pump are used as the heat sources of the main humidifier and the pre-humidifier, respectively. Through parametric studies, a comparative analysis is conducted on the thermodynamic and economic performances of both the heat pump operated single-stage system and two-stage system at various operating conditions. The results show that such system modification can greatly improve system performances. Compared to the single-stage system, the maximum freshwater productivity of the two-stage system is 42.89 kg/h, increased by 19.77 %; the peak gain output ratio is 7.93, up by 9.53 %; and the lowest specific electricity consumption is 79.34 kWh/m, reduced by 15.15 %. Furthermore, the freshwater production cost for the two-stage system, ranging from 7.78 to 13.33 $/m, is also superior that of the single-stage system, further demonstrating its substantial value in practical product development and market promotion.

中文翻译：

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带过冷器和回热器的热泵运行两级加湿除湿海水淡化系统分析

热泵操作的单级加湿除湿海水淡化系统配备过冷器和回热器，已被证明在提高淡水生产力和能源效率方面非常有效。为了研究增加加湿级数的潜在好处，本文提出了一种通过添加预加湿器的热泵操作的两级加湿-除湿海水淡化系统。热泵的过冷器和冷凝器分别作为主加湿器和预加湿器的热源。通过参数研究，对热泵单级系统和两级系统在不同工况下的热力性能和经济性能进行了比较分析。结果表明，这样的系统修改可以极大地提高系统性能。与单级系统相比，两级系统的最大淡水生产率为42.89 kg/h，提高了19.77%；峰值增益输出比7.93，提升9.53%；具体用电量最低为79.34千瓦时/平方米，降低15.15%。此外，两级系统的淡水生产成本为7.78至13.33 $/m，也优于单级系统，进一步证明了其在实际产品开发和市场推广方面的巨大价值。