Cooling System and Temperature Control of an Enclosure using Peltier Modules

Abstract

Reaching of negative temperatures for various applications such as food industry, medicine or experimental physics implies the use of cryogenic fluids (especially liquid nitrogen) or refrigeration heat pumps. The technological progress in materials science in the last years allowed the development of other methods to obtain low temperatures needed for such applications, by means of using the Peltier effect. The Peltier modules were developed and perfected in last decades, in order to allow temperature differences of 20 ºC to 85 ºC between the two faces of one module when one side is kept at room temperature, and an electric current is supplied. Thus, the possibility of developing devices which allow obtaining and controlling temperatures up to -50 ºC were opened, eliminating all the difficulties related to the use of cryogenic agents, which imply the need of Dewar storage vessels, cryogenic transfer lines and controlling of cryogenic liquid such as liquid helium or liquid nitrogen (with boiling temperature of -196 ºC, at atmospheric pressure) or refrigeration systems. In this work are presented the design, execution and testing results of a thermally controlled enclosure aimed for the calibration of temperature sensors, in the range of -50 to +20 ºC, using Peltier modules. Despite the high electric power consumption of the Peltier modules needed to cool down the enclosure due to the low COP (coefficient of performance) compared to the conventional refrigeration systems, this approach in obtaining negative temperatures presents important advantages such as the lack of maintenance, low volume, simplicity of temperature control and high temperature stability (0.1 ºC).