Arduino based temperature and humidity control for condensation on wettability engineered surfaces

Condensation is a ubiquitous phenomenon which depends on several factors, ranging from the degree of subcooling to the relative humidity of the condensing environment. Characterizing condensation in experimental setups, therefore, requires a proper control strategy of operating parameters. Although industrial vapor chambers are available for carrying out condensation experiments under precisely controlled environments, these setups are prohibitively expensive. Here we have developed a low-cost, prototype vapor chamber that is equipped with advanced control systems. Environmental control aspects of a Styrofoam- made condensation chamber are developed in-house for testing condensation on wettability engineered surfaces. Peltier-heat sink arrangement is used to cool the condenser surface under study and the desired relative humidity is maintained within the chamber by means of spraying deionized water with a nebuliser. In order to automate the process, an Arduino Duemilanove board is amalgamated with the setup. Temperature is controlled by an ON/OFF trigger-driven mechanical relay connected to the Arduino environment, which in turn generates an opportunely amplified signal to control the supply voltage of the Peltier element. A K-type thermocouple is interfaced to the Arduino board with the help of MAX31855K thermocouple amplifier for measuring the plate temperature. For humidity and chamber-temperature monitoring, an SHT35D sensor is used. The relative humidity of the chamber is maintained by a mechanical relay-driven spray arrangement. The time-domain plots of humidity and plate temperature response indicates that the temperature fluctuations are within 0.25°C and RH fluctuations are within 0.5% about the set-point. Transient response of the temperature and RH data are monitored by the Serial Monitor of Arduino software, which indicates that the set values of temperature and RH are obtained approximately within 0 to 1000 seconds.