A novel small hybrid system for cooling and water purification: Integrating conical split thermoelectric cooler with direct contact membrane distillation

To improve energy efficiency of thermoelectric cooler (TEC), this paper presents an integrated and portable hybrid system that utilizes the heating capacity of conical split thermoelectric cooler (STEC) to drive direct contact membrane distillation (DCMD) for simultaneous cooling and freshwater production. The specialized thermoelectric modules of COMSOL is used for 3D modeling to compare the performance improvement of conical STEC over traditional thermoelectric cooler. The effects of input current and cold-end temperature of STEC, feed and permeate fluid temperatures, and fluid flow velocity on the performance of the STEC/DCMD system are analyzed by collaboration application of COMSOL and MATLAB. The results demonstrate that under the same conditions, conical STEC has lower cold-end temperature and wider working range than traditional TEC. The conical STEC reveals superior performance in large temperature difference with the cooling efficiency significantly exceeding that of traditional TEC. The cooling capacity and permeate flux are improved by 162.42% and 26.31% when the current is increased from 3 A to 7.5 A. The freshwater production capacity and the total efficiency of the STEC/DCMD hybrid system are significantly enhanced with increase in the feed-fluid temperature. Changing the flow velocity and temperature of permeate-fluid can improve freshwater production capacity and total efficiency without negative effect on the cooling performance of STEC. The STEC/DCMD hybrid system has relatively high flexibility and high portability to effectively utilize the STEC heat and improve the overall energy efficiency. The obtained results may provide useful information for developing STEC and DCMD small-scale hybrid system for simultaneous cooling and water purifications.