Electronic multiplex system using the Arduino platform to control and record the data of the temperatures profiles in heat storage tank for solar collector

Abstract

This work aims to build a monitoring thermal system based on low cost and using the Arduino MEGA platform. To the temperature, measurements are used thirty (30) digital sensors (DS18B20 Dallas) boarded together using three (3) wires, therefore, requiring the “One Wire” library to allow a correct read in the Arduino software. Using the Dallas sensors and the Arduino programming, it is possible monitoring the temperatures of up to 100 and twenty (120) different points, thereby significantly reducing electric problems and also the diameter of the thermal probe from uses only three (3) wires. The use of thirty (30) digital sensors significantly reduces the electrical problems and increases the processing speed using the multiplexing through the electrical connection to three (3) wires, called “normal power mode”. Using the thermal probe, which is installed, vertically inside the reservoir, it is possible to obtain the temperature graphical points, thus allowing the analysis of thermal stratification. The software used is Arduino IDE based in a language called CCS (C, C++ and “Wiring”). The water inside the reservoir stores energy in the form of sensible heat, based on the importance of the thermodynamics analysis result for this research, therefore, with some temperature, data samples obtained in thermal probe are possible to analyze the thermal stratification in the reservoir. The thermal efficiency of the energy stored in the water, either thermally stratified or homogeneous, analyzed to the first law of thermodynamics, it is the same. In the case of the second law of thermodynamics, the heat efficiency to heat homogenized water is less than the thermal efficiency in the stored water thermally stratified in the reservoir and both of them are lower than the first law of thermodynamics.