Steam Generation in Line-Focus Solar Collectors: A Comparative Assessment of Thermal Performance, Operating Stability, and Cost Issues

摘要

The engineering and system benefits of using direct steam (in situ) generation in line-focus collectors are assessed. The major emphasis of the analysis is a detailed thermal performance comparison of in situ systems (which utilize unfired boilers). The analysis model developed for this study is discussed in detail. An analysis of potential flow stability problems is also provided along with a cursory cost analysis and an assessment of freeze protection, safety, and control issues. Results indicated a significant thermal performance advantage over the more conventional oil and flash systems and the flow stability does not appear to be a significant problem. In particular, at steam temperatures of 220 exp 0 C (430 exp 0 F) under the chosen set of assumptions, annual delivered energy predictions indicate that the in situ system can deliver 15% more energy than an oil system and 12% more energy than a flash system, with all of the systems using the same collector field. Further, the in situ system may result in a 10% capital cost reduction. Other advantages include improvement in simpler control when compared with flash systems, and fluid handling and safety enhancement when compared with oil systems. (ERA citation 07:042998)