热管式两级热电冷水机性能分析与优化

Performance analysis and optimization of two-stage heat pipe-cooled thermoelectric chiller

  • 摘要: 针对热管良好的散热能力和两级热电制冷器能达到更大的制冷温差的特性,提出了一种基于热管散热的两级热电冷水机模型。基于有限时间热力学和非平衡热力学,考虑包括汤姆逊效应在内的各种热电效应,用数值模拟的方法分析了恒温热源下工作电流、热电单元分配比以及热管几何参数(热管外径、蒸发段长度和吸液芯厚度)对装置制冷率、制冷系数和极限制冷温差的影响。在热电单元总对数一定的约束条件下,分别以制冷率和制冷系数最大为目标,以电流和热电单元分配比为优化变量,优化了装置性能,并分析了关键参数对最优变量和最优性能的影响,得到了协调制冷率和制冷系数的最优区间。通过优化热电单元分配比和电流,装置制冷率和制冷系数有了较大的提升。当\Delta T\text=\text20 Kx = 0.6,I = 2.5 A时,优化后的制冷率和制冷系数分别达到23.42 W和1.53,较优化前分别提高了12.11%和218.75%。

     

    Abstract: When compared with the traditional refrigeration method that uses a refrigerant as a working medium, thermoelectric refrigeration is a new type of solid-state active environmental protection refrigeration method. This method is based on the Peltier effect of semiconductor thermoelectric materials, which directly converts electrical energy into a temperature gradient. Thermoelectric refrigeration has the advantages of simple structure, compact structure, rapid cooling, and accurate control of refrigeration temperature. When compared with a single-stage thermoelectric cooler, a two-stage thermoelectric cooler can ensure greater cooling temperature difference and efficiency. A heat pipe is a heat transfer component that uses liquid-phase transition to transfer heat. It has good isothermal stability, efficient thermal conductivity, and small size. For good heat dissipation capacity of heat pipes and higher cooling temperature difference in two-stage thermoelectric coolers, a two-stage thermoelectric chiller model based on heat pipe heat dissipation is proposed. Based on finite-time and nonequilibrium thermodynamics, various thermoelectric effects, including the Thomson effect, are considered. The effects of working current, distribution ratio of thermoelectric elements, and heat pipe geometric parameters (heat pipe outer diameter, evaporating section length, and wick thickness) on the device-cooling load, coefficient of performance (COP), and extreme cooling temperature difference are analyzed by the numerical simulation method. Under a certain total logarithm constraint of the thermoelectric unit, the cooling load and the COP are taken as the targets. The working current and distribution ratio of thermoelectric elements are used as the variables to optimize device performance. The influence of key parameters on the optimal variables and optimal performance is analyzed, and the optimal interval of the coordinated cooling load and COP is obtained. By optimizing the distribution ratio and current of thermoelectric elements, the cooling load and COP of the device significantly improved. When \Delta T\text\text=\text\text20 K, x = 0.6, I = 2.5 A, the optimized cooling load and COP reach 23.42 W and 1.53, respectively, which are 12.11% and 218.75% higher than those before optimization.

     

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