Experimental analysis of a multi shape grooved receiver tube for a parabolic trough solar collector

• The parabolic trough concentrator was experimentally investigated using multi-shape grooved receiver tubes. • Four absorber-tube geometries were examined: circular, triangular, rectangular, and crescent-grooved tubes. • The thermal performance of all new absorber shapes was compared with that of the conventional circular tube. • The collector efficiency (η) reached a maximum value of 73.1%, representing a 34.5% increase over the regular model. Experimental analysis for the tube that absorbs reflected solar energy ( S Tu ) of a Parabolic Trough Solar Collector ( PTSC ) was conducted to develop its ability to convert energy and improve its performance by modifying the geometric shape of the ( S Tu ) from the usual form (circular) to a grooved tube, with suggested multiple shapes for the groove channel section (triangle, rectangular, crescent)), and testing their performance experimentally. Improving the ability of the ( S Tu ) to convert solar energy was achieved by relying on the principle of increasing the surface area on which the incident rays of solar energy are focused, thus expanding the window through which solar energy penetrates into the tube to be transformed into thermal energy for the heat transfer fluid ( HTF ). The cross-sectional shape of the tube was changed while keeping the cross-sectional area of the tube constant, Thus, the velocity of the fluid remains the same, and the time for the fluid molecules to pass through the tube is unchanged. Four tubes were examined, three of them grooved, Triangle grooved tube ( TGT ), crescent grooved tube ( CGT ), and rectangular grooved tube ( RGT ), The performance of all tubes was compared with the regular tube ( RT ), all with the same mass flow rate ( m ˙ =3 L/min). The outcomes presented a noticeable enhancement in heat transfer improvement for most grooved models, with a greater heat transfer in the ( TGT ) compared to the plain tube. With the developed model ( TGT ) the Collector efficiency ( η ) recorded the highest value, equal (73.1%) with an increase of (34.5%,) over the regular model, an improvement was recorded in the average convective heat transfer coefficient at the inner surface of the tube in the TGT , resulting in a 39.5% increase in the Nusselt number ( Nu ) compared to the reference tube ( RT ), with a slight increase in the pressure difference of the ( HTF ).