| Title |
Fluid Sensor and Algorithm for Trouble Detection of Solar Thermal System |
| Authors |
이원철(Won-Chul Lee) ; 홍희기(Hiki Hong) |
| DOI |
http://dx.doi.org/10.6110/KJACR.2014.26.8.351 |
| Keywords |
태양열 시스템 ; 고장진단 ; 전기저항 ; 반응표면분석 ; 유체센서 Solar thermal system ; Trouble detection ; Electric resistance ; Response surface analysis ; Fluid sensor |
| Abstract |
Typical trouble patterns in solar thermal systems include working fluid leakage and freezing other than breakdown of pump. A fluid sensor for measuring electric resistance of fluid was developed and installed at the top of the collector piping in order to check the fault of solar system. Working fluid level in the pipe was determined by measuring electric resistance from a fluid sensor. On the base of this, it was confirmed that the fluid sensor diagnoses leakage of fluid. Electric resistance of propylene glycol aqueous solution was measured in the range of 0∼70℃ and 0∼40% of concentration. The response surface analysis was performed by using a central composite design, and the regression equation was derived from the relationship between electric resistance, temperature, and concentration. Through the experiment in a real solar system, we can estimate a concentration of working fluid when a pump is not operating and predict a possibility of freezing. Finally, an effective algorithm for trouble shooting was proposed to operate and maintain the solar system. |