Analysis of an integrated collector storage system with vacuum glazing and compound parabolic concentrator

Abstract

The basic problems encountered in Integrated Collector Storage (ICS) devices are the heavy evening-to-morning heat losses, the weak ability to capture solar radiation and the thermal losses due to the heat transfer in front of the single glazing. In this study, a new ICS with Compound Parabolic Concentrator (CPC) for domestic uses was designed, constructed, tested and numerically studied. The novelty in the designed ICS system is the use of transparent vacuum insulation in the annulus between double half-cylindrical plexiglass, the use of automated insulation system which suppresses heat loss during night. Experimental results showed that the loss coefficient of the ICS decreased from 5.41 W/K.m2 to 3.34 W/K.m2 when we created the vacuum and used the night insulation system. Numerical study was also accomplished by using FORTRAN simulation program solving energy balance equations of the ICS. The program was used to study the effect of pertinent parameters namely night insulation, CPC reflectivity and vacuum on the thermal performance of the system. The analysis results of the water storage tank, the absorber and the plexiglass temperatures showed the validity of the developed model. The parametric study clearly showed that an increase of the concentrator reflectivity yields to an increase of the system efficiency. Numerical study also showed that if we succeed in making perfect night insulation and vacuum, the daily efficiency reaches 58.62% and the loss coefficient decreases significantly to1.68 W/K.m2.