An efficient and economic evacuated U-tube solar collector powered air gap membrane distillation hybrid system for seawater desalination

Solar-powered membrane distillation is a promising desalination technology that can provide accessible and reliable freshwater for coastal and island households. However, high installment cost and low efficiency are two main hindering factors restricting the widespread application of this technology. To solve these issues, a low-cost air gap membrane distillation (AGMD) desalination system powered by efficient evacuated U-tube solar collector (EUSC) is put forward to theoretically predict its effectiveness. A system-scale mathematical model for the proposed hybrid system is established and validated. The system performance is predicted under the weather conditions of southeast China (Ningbo city). The maximum permeate flux, energy efficiency and exergy effi-ciency are, respectively, 3.16 kg m- 2 h-1, 56.71% and 0.38%, showing a bright application prospect. Numerous parametric studies are undertaken to explore how to further enhance the performance of this technique. The long-term running performance for the year of 2021 and last 41 years is also revealed. The yearly average production is about 6452 kg, which can satisfy the drinking water demand for a household of 6 members. Furthermore, economic study is presented and the levelized cost of water is only 8.54 $/m3. The proposed EUSC/ AGMD coupling system is an efficient and economic alternative for small-scale solar seawater desalination.