Stack Thermo-Osmotic System for Low-Grade Thermal Energy Conversion

J Li and ZK Zhang and RZ Zhao and B Zhang and YM Liang and R Long and W Liu and ZC Liu, ACS APPLIED MATERIALS & INTERFACES, 13, 21371-21378 (2021).

DOI: 10.1021/acsami.1c03395

Thermo-osmotic energy conversion (TOEC) technology, developed from membrane distillation, is an emerging method that has the potential of obtaining electricity efficiently from a low-grade heat source but faces the difficult problem of pump power loss. In this study, we build a novel TOEC system with a multistage architecture that can work without pump assistance. The experiment system, made of cheap commercial materials, can obtain a power density of 1.39 +/- 0.25 W/m(2), with a heating temperature of 80 degrees C, and its efficiency increased linearly with the total stage number. A theory calculation shows that a 30-stage system with a specific membrane and a working pressure of 5.0 MPa can obtain an efficiency of 2.72% with a power density of 14.0 W/m(2). By a molecular dynamics simulation, it is shown that a high- performance membrane has the potential to work at 40 MPa. This study proves that TOEC technology is a practical and competitive approach to covert low-grade thermal energy into power efficiently.

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