Fundamental Limits of the Dew-Harvesting Technology

IF 2.7 3区工程技术 Q2 ENGINEERING, MECHANICAL

Nanoscale and Microscale Thermophysical Engineering Pub Date : 2019-09-12 DOI:10.1080/15567265.2020.1722300

Minghao Dong, Zheng Zhang, Yu Shi, Xiaodong Zhao, S. Fan, Zhen Chen

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引用次数: 27

Abstract

ABSTRACT Dew-harvesting technology radiatively cools a condenser below the dewpoint to achieve condensation of the water vapor from the atmosphere. Due to its passive nature, this technology has attracted broad interest, in particular in the context of the worldwide drinking-water scarcity. However, the fundamental limit of its performance has not yet been clarified. Moreover, the existing applications have been limited to humid areas. Here, we point out the upper bound of the performance of this technology by carefully considering various parameters such as the ambient temperature (Tambient), the relative humidity (RH), and the convection coefficient (h). Moreover, we highlight the potential of a condenser consisting of a selective emitter, which is capable of condensing water vapor under significantly more arid conditions as compared with the use of a blackbody emitter. For example, a near-ideal emitter could achieve a dew-harvesting mass flux () of 13 gm−2hr−1 even at Tambient = 20°C with RH = 40%, under which condition the blackbody emitter cannot harvest any dew. We provide a numerical design of such a selective emitter, consisting of six layers, optimized for dew-harvesting purposes.

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采露技术的基本局限

摘要：采露技术将冷凝器辐射冷却至露点以下，以实现大气中水蒸气的冷凝。由于其被动性，这项技术引起了广泛的兴趣，特别是在全球饮用水短缺的背景下。然而，其性能的根本限制尚未得到澄清。此外，现有的应用仅限于潮湿地区。在这里，我们通过仔细考虑环境温度（Tambient）、相对湿度（RH）和对流系数（h）等各种参数，指出了该技术性能的上限。此外，我们强调了由选择性发射器组成的冷凝器的潜力，与使用黑体发射器相比，该冷凝器能够在更干旱的条件下冷凝水蒸气。例如，即使在Tambient=20°C、RH=40%的条件下，接近理想的发射器也可以实现13 gm−2hr−1的露水收集质量通量（），在这种情况下，黑体发射器无法收集任何露水。我们提供了这种选择性发射器的数值设计，该发射器由六层组成，针对采露目的进行了优化。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Nanoscale and Microscale Thermophysical Engineering 工程技术-材料科学：表征与测试

CiteScore

5.90

自引率

2.40%

发文量

审稿时长

3.3 months

期刊介绍： Nanoscale and Microscale Thermophysical Engineering is a journal covering the basic science and engineering of nanoscale and microscale energy and mass transport, conversion, and storage processes. In addition, the journal addresses the uses of these principles for device and system applications in the fields of energy, environment, information, medicine, and transportation. The journal publishes both original research articles and reviews of historical accounts, latest progresses, and future directions in this rapidly advancing field. Papers deal with such topics as: transport and interactions of electrons, phonons, photons, and spins in solids, interfacial energy transport and phase change processes, microscale and nanoscale fluid and mass transport and chemical reaction, molecular-level energy transport, storage, conversion, reaction, and phase transition, near field thermal radiation and plasmonic effects, ultrafast and high spatial resolution measurements, multi length and time scale modeling and computations, processing of nanostructured materials, including composites, micro and nanoscale manufacturing, energy conversion and storage devices and systems, thermal management devices and systems, microfluidic and nanofluidic devices and systems, molecular analysis devices and systems.