Modelling and Design of Direct Solar Steam Generating Collector Fields

Abstract

The direct steam generation (DSG) is an attractive option regarding the economic improvement of parabolic trough technology for solar thermal electricity generation in the multi megawatt range. According to Price, H., Lu¨pfert, E., Kearney, D., Zarza, E., Cohen, G., Gee, R. Mahoney, R., 2002, “Advances in Parabolic Trough Solar Power Technology,” J. Sol. Energy Eng., 124 and Zarza, E., 2002, DISS Phase II-Final Project Report, EU Project No. JOR3-CT 980277 a 10% reduction of the LEC is expected compared to conventional SEGS like parabolic trough power plants. The European DISS project has proven the feasibility of the DSG process under real solar conditions at pressures up to 100 bar and temperatures up to 400°C in more than 4000 operation hours (Eck, M., Zarza, E., Eickhoff, M., Rheinla¨nder, J., Valenzuela, L., 2003, “Applied Research Concerning the Direct Steam Generation in Parabolic Troughs,” Solar Energy 74, pp. 341–351). In a next step the detailed engineering for a precommercial DSG solar thermal power plant will be performed. This detailed engineering of the collector field requires the consideration of the occurring thermohydraulic phenomena and their influence on the stability of the absorber tubes.

Numerical simulation of direct solar steam generation collectors with parabolic troughs

“…The void fraction Ƚ represents the ratio of the vapor crosssectional area and the cross-sectional area of the tube, it is determined by the equation of Rouhani [9] [10].…”

Transient data for flow of evaporating fluid in parallel mini pipes and comparison with theoretical simulations

“…In the new generation of the solar power plants, based on the parabolic trough technology, steam is generated directly in an array of parallel pipes instead of using oil as a secondary heating medium (Zarza et al, 2006;Eck and Steinmann, 2005;Eck and Hirsch, 2007). Evaporating fluid in parallel mini and micro channels is a promising tool for cooling high heat flux electronic devices (Kandlikar et al, 2006;Thome, 2006).…”

Analysis and potential of once-through steam generators in line focus systems – Final results of the DUKE project

“…In general, a detailed stress analysis depending on the receiver material and wall thickness is advised to identify an appropriate limit of the temperature gradient. For simplicity, the 50 K limit as in [6] is shown in the figure, which already offers some safety margin in the DISS case. At 800 W/m² of effective irradiation (incident on the absorber tube), a minimum mass flow of 0.6 kg/s is needed to stay below the recommended limit.…”

“…Analyses on the superheating section have already been suggested e.g. in [6]. In the present paper, the Finite Element Method (FEM) model in ANSYS as presented in [7] is applied to the last receiver at the outlet of the DISS test loop for a steam temperature of 400°C.…”