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Experimental investigation of a low-cost humidification-dehumidification desalination cycle using packed-bed humidifier and finned-tube heat exchanger
K. Garg, R. Beniwal, , H. Tyagi
Published in Elsevier Ltd
Volume: 41
Humidification-Dehumidification (HDH) desalination technology can ensure adequate freshwater supply to the people living in water-stressed regions in remote locations. Although, HDH process can be operated by using simple and inexpensive components such as cooling tower and heat exchanger which are readily available in the market. But to achieve the desired freshwater productivity and thermal performance, it is important to carry out the detailed design of these components and choose the right operating parameters such as mass flow rate ratio, top brine temperature which significantly affects system performance. In the present study, the thermal performance of a closed-air, open-water and water-heated version of the HDH cycle has been investigated experimentally and the previously developed detailed numerical model for the similar HDH cycle has been validated with the experimental results. The HDH system has been built with a counter-flow packed-bed cooling tower and finned-tube heat exchangers which are widely utilized across all industries. The thermal performance of the system is evaluated in terms of four main parameters which are gained output ratio (GOR), distillate flow rate, and the effectiveness of the humidifier as well as the dehumidifier by varying the top brine temperature as well as the mass flow rate ratio. It is observed that the present system can produce around 125.5 L of freshwater per day, having total dissolved solids of approximately less than 15 ppm, operating at a feed temperature of only 61.7 °C and mass flow rate ratio (MR) of 2.34. At these operating conditions, energy effectiveness of the humidifier and dehumidifier were approximately 0.75 and 0.80. The gained output ratio (GOR) of the present system is quite modest (=0.81) which indicates that the system may be further improved in the future. The results of our current experimental study validated the predictions of the model developed in our prior study. Hence, the model can be utilized to design the HDH system as per the desired output of freshwater and GOR. The results from both experiments and simulations are in closer agreement with each other. The numerical analysis also showed that the integration of solar energy-driven AHT (Absorption Heat Transformer) has the potential to further increase the production rate of the HDH system. The economic performance of the system revealed the levelized cost of water production (LCOW) from such a system is approximately USD 4.0 $/m3 of fresh water but the total capital expenditure to install this system is very low (<USD $1500). Overall, it was inferred that an HDH system with optimum performance can be designed and installed at a much lower cost, and using simple construction, which is a huge advantage for marginalized communities living in remote locations across the world (since the simple components of this system can be easily operated and maintained by them). © 2023 Elsevier Ltd
About the journal
JournalThermal Science and Engineering Progress
PublisherElsevier Ltd