| In industrial production and daily life,there is a large amount of waste heat.Especially the low-temperature waste heat below 200 ℃,due to its low energy level and diverse resource environment,the efficiency of recycling these waste heat is low and the cost is high.Thermoelectric power generation(TEG)technology is a kind of energy conversion technology that can directly generate electricity using temperature difference,and has the advantages of wide heat source’s adaptability,no limitation of temperature difference,light weight,small size,environmental protection and so on.Therefore,the application of TEG technology in the recycling of low-temperature heat source has great potential.At present,compared with the medium and high temperature heat source,the research on the recovery and utilization of the TEG technology in the low temperature heat source is relatively few and TEG technology has not been widely used.The reason is that the TEG technology has low efficiency and the high cost under low-temperature heat sources.In order to improve the performance and cost performance of the TEG system,the following research work has been carried out:(1)A multi-module segmented series/parallel TEG system is proposed;Based on the thermoelectric effect and the basic theory of heat transfer,a one-dimensional multiphysics coupling model about the internal modules’ thermoelectric effect and the external heat / cold source flow heat transfer is set up,the characteristics(Seebeck coefficient,electrical conductivity,thermal conductivity)of P and N-type TE couple with different temperature and the temperature variation under heat / cold source countercurrent are considered.(2)Under certain heat/cold source condition,the TEG system with TE module areas of 0.02 m × 0.02 m and 0.04 m × 0.04 m and the modules’ number of 5,10,20,and 50 are optimized.From the aspects of single,double,multiple factors,TEG system performance is analyzed,the effects of fill factor,TE couple length,external load and their combinations on system performance are revealed.The results show that,when the fill factor,TE couple length and external load increase gradually,the output power shows a parabolic relation.With the increase of the TE couple length,the optimal fill factor and the optimal external load increase,but the maximum output power is almost unchanged.Therefore,when the mechanical manufacturing process is satisfied,the system with short TE couple length,small fill factor and small external load can be manufactured to improve the cost performance of the TEG system.After optimization,the output power of parallel and series TEG systems are almost equal,but the internal resistance and the optimal external load are much smaller in parallel system.Therefore,the parallel TEG system or series TEG system can be selected according to the actual load external resistance.(3)The finned radiator is designed,the effective heat dissipation coefficient model of TEG system is established,and the influence of the fin’s number on the performance and cost performance in the multi-module segmented series TEG system is analyzed.It is found that compared with non-finned fins,the performance and economy of TEG systems using finned radiators have been effectively improved.As the length of the TE couple increases,the benefit of increasing the fin’s number decreases.When the length of the TE couple is 0.2mm,with the increase of the fin’s number,the decline rate of cost-power ratio can reach 50.2%;when the length of the TE couple is 4.2mm,the decline rate of cost-power ratio is only 4.2%. |
