Achieving Temperature stability of the system
Below are the requirements of the end user for temperature maintenance of the system.
- Lamp seals of the solar simulator had to be maintained below 230˚C. But traditional forced air cooling could not be performed when the solar simulator is hosted within a vacuum chamber.
- Fresnel optical elements traditionally used with this type of simulator had to be maintained at temperatures below 80˚C.
- The lamp envelope required some cooling which could only be done by passing air or gas over the lamp envelope.
Testing the temperature stability
Sciencetech engineers determined that the best approach was to build a pressure vessel to house the simulator and optics. The pressure vessel allowed cold liquid to be pumped into the chamber and routed to a series of radiators which performed heat transferring inside the chamber via forced air through the radiators. The anode and cathode of the lamp base was cooled with a water re-circulator filled with de-ionized water.
Since Sciencetech is committed to providing the best solutions to complex engineering problems, we specifically built a test chamber to perform these cooling experiments. We progressed through a series of failed prototypes and burnt-out lamps and power supplies before arriving at a successful cooling system.
Control electronics were designed specially to be integrated with the solar simulator. Internal system temperature sensors and coolant flow sensors were built in to protect the system in case of any component malfunctioning. Temperature sensors were also placed at two different locations inside the housing to monitor the internal air temperature.
Another temperature sensor was used to monitor the temperature of the water bath in the re-circulator that was used to cool the lamp bases.
A logic circuit was used to turn off the lamp in case an over temperature condition occurs at a lamp base or inside the housing. The logic circuit was used to set temperature points and to control a relay which will cut power to the lamp in case of an over temperature event.