Introduction: The use of energy requires collection systems to improve heat transfer capacity.
Objective: To evaluate the effect of the incorporation of microparticles in the process fluid of a compound parabolic collector (CPC) on its ability to operate.
Methodology: A CPC incorporated with activated carbon (102.2 nm), Chinese ink (198.4 nm) and copper particles (160.1 nm) was evaluated for operation at four angles of inclination (30, 35, 40 and 45°).
Results: The energy collection was based on a natural convection mechanism, with a film coefficient that varied between 10.6 and 15.8 W∙m^-2∙°C^-1. The operation with 30° inclination showed the best characteristics of radiant energy collection, where the energy efficiency was 44.6 % for the system based on pure water, 61.0 % with copper particles, 63.2 % with activated carbon and 68.4 % with Chinese ink.
Limitations of the study: The study provides values of thermal convection coefficients that correspond to the particular conditions evaluated. In order to evaluate the performance of the system under different conditions, it is necessary to build models based on dimensional analysis that allow the evaluation of heat transfer coefficients in situations of use of diverse operating variables.
Originality: The incorporation of microparticles in the process fluid increases the potential for collecting radiant energy from a CPC.
Conclusions: The use of microparticles has the potential to improve the operation of a CPC.

....