https://orcid.org/0000-0002-3138-4786
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ABSTRACT
Amidst increasing fresh water crisis, sorption based solar powered atmospheric water harvesting (SPAWH) offers a promising solution to this problem. The available sorption based systems use composite desiccants that are expensive and artificially processed, which restricts their scalability and practical implementation. Moreover, the required desorption temperature available from the system is also low. The proposed system develops and experimentally investigates a novel composite desiccant material synthesized using anhydrous CaCl₂ impregnated in Jute (intrinsic host material), which is cheap and naturally available. To desorb the composite desiccant, 4.86 m2 double-ended vacuum tube collector is used, which produces peak hot air temperature of 134.2°C. The developed system using 12 kg composite of Jute/CaCl₂ harvests 5850 ml/day of water at 0.086 $/L cost with 13.93% thermal and 8.66% exergy efficiency. The results of the water analysis verify that the harvested water is of good quality and is safe for use.
Nomenclatures
| = | Area of collector (m2) | |
| = | Capital recovery factor | |
| = | Salvage cost ($) | |
| = | Energy rating of blower-B (kW-h) | |
| = | Energy rating of exhaust fan-E (kW-hr) | |
| = | Initial cost ($) | |
| = | Water harvesting coefficient | |
| = | Solar intensity (W/m2) | |
| = | Latent heat (kJ) | |
| = | Mass flow rate of air (kg/hr) | |
| = | Maintenance cost ($) | |
| = | Weight of water (Kg) | |
| = | Years of working life | |
| = | Net cost ($) | |
| = | Electric energy consumption (kW-hr) | |
| = | Running cost ($) | |
| = | Rate of interest (%) | |
| = | Desorption rate (Kg/hr) | |
| = | Sorption rate (Kg/hr) | |
| = | Sinking fund factor | |
| = | Time (Hr) | |
| = | Atmospheric temperature (k) | |
| = | Hot air temperature (k) | |
| = | Sun temperature (k) | |
| = | Annual salvage cost ($) | |
| = | Annual cost ($) | |
| = | Water-energy coefficient | |
| = | Humidity ratio (in) | |
| = | Humidity ratio (out) | |
| = | Cost of water ($/L) | |
| = | Exergy efficiency (%) | |
| = | Overall efficiency (%) | |
| = | Thermal efficiency (%) | |
| Abbreviations | = | |
| DBT | = | Dry bulb temperature |
| DPT | = | Dew point temperature |
| HX | = | Heat exchanger |
| DE-VTC | = | Double-ended vacuum tube collector |
| SE-VTC | = | Single-ended vacuum tube collector |
| Subscripts | = | |
| = | Condensation | |
| = | Dry air | |
| = | Desorption | |
| = | Sorption |
Acknowledgements
The authors would like to thank Pollucon laboratory that is situated in Surat city (Gujarat) for providing us the accurate test reports of the water sample from their owned test facility. Authors would also like to extend the thanksgiving to Dr. H.K. Dave for providing the SEM images of the test sample.
Disclosure statement
No potential conflict of interest was reported by the author(s).
Scope for future work
Since, the present host material Jute has provided significant results with CaCl₂, it can be synthesized with other liquid desiccant materials like potassium formate, lithium bromide, and lithium chloride in order to enhance the system productivity and reduce the cost of water per liter. Further, other novel composite desiccants can be investigated to ensure the feasibility of the system under wide range of operating conditions.
Additional information
Funding
Notes on contributors
Anshu Agrawal
Anshu Agrawal is a PhD student at S.V. National Insitute of Technology Surat, specializing in atmospheric water harvesting. His research focuses on solar air heating and desiccant materials.
Amit Kumar
Amit Kumar received the Ph.D. degree in Thermal Engineering from National Institute of Technology Kurukshetra. Currently, he is an Assistant Professor at S.V. National Insitute of Technology Surat. His research interests include desiccant air conditioning, solar thermal desalination, water generation from atmospheric air and adsorption refrigeration.