The thermal performance of a low – concentration – ratio compound parabolic concentrator (CPC) solar water heater was predicted during the period of harmattan dust. The effect of the atmospheric turbidity caused by the harmattan dust particles on the performance of the heater was studied by analyzing the scattering of the incident solar beam radiation by employing Mie scattering theory. The influence of particles’ size and the wavelength of sunlight propagation on the effect of turbidity were studied. The results indicated that 17%, 24.57% and 32% reductions in the absorber temperature were observed respectively, for a slightly turbid (β = 0.01), fairly turbid (β = 0.21) and highly turbid (β = 0.41) atmospheric conditions when compared with a clear and dust free condition.

Keywords: Turbidity, harmattan dust particles, scattering, compound parabolic concentrator, water heater, performance.