A novel all-glass evacuated tubular solar steam generator with simplified CPC

Highlights: • A all-glass evacuated tubular solar steam generator consisted of 60 linked collecting units. • Each unit comprises a glass evacuated tube, a simplified CPC and a metal annular tube. • The maximum steam outlet temperature can exceed 200 °C with pressure of 0.55 MPa. • The performance parameters are optimized by experimental study. - Abstract: A low-cost all-glass evacuated tubular solar steam generator with simplified CPC (Compound Parabolic Concentrator) is presented in the paper. It can produce steam exceeding 200 °C with pressure ranging from 0.10 to 0.55 MPa. The solar steam generator primarily consists of 60 collecting units with a total aperture area of 32 m² and each unit is comprised of an all-glass evacuated tube, a simplified CPC and a metal concentric annular tube which is inserted into the all-glass evacuated tube. The high viscosity mixture made of high temperature oil and graphite powder is filled in the annular space between the inner glass tube and the copper concentric tube in order to enhance heat transfer from the selective absorbing layer to working fluid flowing in the concentric tube. Outdoor experimental studies have been carried out to investigate the actual performance of the designed solar steam generator in summer time under different operating conditions. Experimental results show that the maximum steam outlet temperature can exceed 200 °C with pressure of 0.55 MPa. The present solar steam generator can steadily produce saturated steam over 150 °C at the pressure range of 0.1–0.55 MPa with a collecting efficiency over 0.30, which can be used as an industrial steam supplier with great potentials for various applications