Low-Power Heating and Temperature Monitoring
Desert Christian’s International Space Station (DCISS) team consists of eleven high school students with a goal of sending and monitoring an experiment onboard the International Space Station. The objective of the team’s current experiment is the study of the effects of different dielectrics and heating on the performance of graphene-based supercapacitors (GBSC). The challenge has been the development of a low-power heating system to heat various GBSCs to 140°F, given a power budget for the heating system of 0.5 W (5 V at 100 mA).
Given the low-power requirement, and the small volume available for the experiment (15 cubic inches), there was a need to develop a compact and low-power heating system for each of the eight GBSCs to be used. After some discussion, the students realized that resistive temperature detectors (RTDs) provide temperature measurement but also produce heat; they began to experiment with RTDs to determine if they could be used to heat the GBSC devices to the desired 140°F goal. A ground test using a breadboard circuit confirmed that the RTDs could be used as both a low-powered heater and temperature measuring device.
Using Micro-Measurements’ ETG-50B/W temperature sensors, this simple solution provided the DCISS team with the ability to heat up to eight GBSCs with only one being evaluated (heated and monitored) at any given time, thus meeting their experimental goals while remaining within power and volume restrictions. Each side of a GBSC contains an RTD with the excitation of each heater being alternated at any given time. While one of the RTDs is heating one side of the GBSC, temperature measurements are conducted on the RTD on the other side that is not being excited. This alternating method of heating and monitoring allows the GBSC state to be both heated and monitored throughout the experimental time on the ISS.
For more details, please check out the full case study “Low-Power Heaters for a High School Experiment Bound for the International Space Station” available at http://www.micro-measurements.com/related/#CSSTDY.
Click here for the datasheet: Temperature Sensors and LST Networks.