Optimal Control of Centralized Thermoelectric Generation System under Nonuniform Temperature Distribution Using Barnacles Mating Optimization Algorithm

The need for renewable energy resources is ever-increasing due to the concern for environmental issues associated with fossil fuels. Low-cost high-power-density manufacturing techniques for the thermoelectric generators (TEG) have added to the technoeconomic feasibility of the TEG systems as an effective power generation system in heat recovery, cooling, electricity, and engine-efficiency applications. The environment-dependent factors such as the nonuniform distribution of heat, damage to the heat-transfer coating between sinks and sources, and mechanical faults create nonuniform current generation and impedance mismatch causing power loss. As a solution to this nonlinear multisolution problem, an improved MPPT control is presented, which utilizes the improvised barnacle mating optimization (BMO). The case studies are formulated to gauge the performance of the proposed BMP MPPT control under nonuniform temperature distribution. The results are compared to the grey wolf optimization (GWO), particle swarm optimization (PSO), and cuckoo search (CS) algorithm. Faster global maximum power point tracking (GMPP) within 381 ms, higher power tracking efficiency of up to 99.93%, and least oscillation ≈0.8 W are achieved by the proposed BMO with the highest energy harvest on average. The statistical analysis further solidifies the better performance of the proposed controller with the least root mean square error (RMSE), RE, and highest SR.

Effects of Nonuniform Temperature Distribution on Degradation of Lithium-Ion Batteries

The effects of nonuniform temperature distribution on the degradation of lithium-ion (Li-ion) batteries are investigated in this study. A Li-ion battery stack consisting of five 3 Ah pouch cells connected in parallel was tested for 2215 cycles and compared with a single baseline cell. The behaviors of temperature distribution, degradation, and current distribution of the stack were characterized and discussed. Results supported the hypothesis that nonuniform temperature distribution causes nonuniform and accelerated degradation. All cells in the stack experienced higher temperature rise and degraded faster than the baseline cell. In particular, capacity retention of the middle cell in the stack decreased to 50.7% after 2215 cycles, while the baseline cell capacity retention was still 87.8%. The resistance of cells in the stack experienced nonuniform but similar pattern of variation with cycling. The resistances remained stable in early cycles, then experienced a rapid increase, and then became stable again. The middle cell resistance increased abruptly in the last 20 cycles before failure. Current distribution behaviors of the stack also changed significantly during cycling, which was consistent with cell resistance behaviors. The middle cell experienced much higher C rate than average, suggesting that its accelerated degradation can be attributed to the synergized effects of higher local temperature and higher local current.