Investigation of natural convection characteristics in the molding chamber of a 3-D printer cooled by thermoelectric cooling modules

Refrigeration using thermoelectric effect is a hot spot and frontier issue at present for its advantages of simple structure, no refrigerant, and no moving parts. This paper aims at characterizing the natural convection characteristics of air in the molding chamber of a 3-D printer that is cooled by thermoelectric cooling modules (TECMs). The distributions of the temperature and velocity field in the molding chamber are obtained, and the influences of the number of the TECMs and their arrangement modes on the magnitude and the spatial difference of temperature and velocity are analyzed. It is found that the Case 2 arrangement mode that all the TECMs are located on the top of the chamber is characterized as the optimal mode with the lowest final average air temperature and the smallest temperature non-uniformity coefficient of the molding chamber. Based on the optimal arrangement mode, a computational formula that correlates the final average air temperature of molding chamber with the volume of the molding chamber and the number of the TECMs is proposed. The new correlation can reproduce all of the 104 data points within error band of +/- 1.0 degrees C, among which 76.9% of the data can be predicted within error band of +/- 0.5 degrees C. The conclusions of this paper can provide a reference for the application of 3-D printing technology and the design of temperature control scheme of low-temperature molding chamber.