Predict the Decay of the Thermal Performance of Solar Parabolic Trough Concentrators Due to Dust Accumulation

The accumulation of dust on solar collectors and concentrates surfaces is one of the most important problems and challenges suffered by solar energy devices. The effect of the dust accumulation on the mirror surface and transparent cover of the receiver tube for the parabolic trough concentrator on the energy gained and the outlet temperature were studied theoretically. The change in the outlet temperature and the thermal energy gained were predicted at different dust concentration factor using the transient simulation system TRNSYS. The average value of the outlet temperature reduced from 465.3 to 366.1 ÂoC with decreasing the cleanliness factor for the mirror only from 1 to 0.4, respectively. Also, the daily thermal energy gained was reduced from 52.78 to 18.14 GJ respectively. While for a cleanliness factor range from 1 to 0.4 for both reflecting mirror surface and the glass cover of the receiver, tube the decay of the outlet temperature and the daily solar energy gained were more ill where the outlet temperature the daily energy gained were reduced to 318.4 °C and 4.496 GJ, respectively. The energy consumed by the auxiliary heater to compensate for the shortage of solar collected energy increased from 9.46 to 33.7 GJ for a decrease in a cleanliness factor range from 1 to 0.6 respectively. From the study, it is evident that the accumulation of dust has a significantly bad effect on the solar energy gained, where a decrease in the cleanliness factor by about 0.1 decreases the collected energy by about 19.9 %.