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

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 ∆T=20 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. © 2022 Science Press. All rights reserved.