Analytical parametric study of an evacuated tube solar air heater with perforated twisted tape for industrial heating applications

A major challenge in creating a vacuum solar tube air collector for industrial use is selecting the optimal thermal networks to reach the desired temperature for a specific flow rate. To develop a thermal network model using empirical correlations for industrial process heat applications, a theoretical analysis is performed to evaluate design features like the diameter and length of the evacuated tubes, as well as the quantity of tubes in a module, all of which impact thermal performance. The results of the design parametric study indicate that a collector system is best characterized by 20 evacuated tubes, each with an absorber and transparent diameters of 47 mm & 58 mm length of 1800 mm, respectively. Additionally, as the number of collectors in a series network increase, there is a notable reduction in the temperature rise for each collection. Based on the thermal network composed of two modules operating at 300 kg/h can provide optimum performance. The results indicate that the proposed evacuated tube solar system is capable of efficiently supplying hot air at temperatures between 80 and 100 °C, making it suitable for a range of industrial process heating applications.