Page 9 - Design of Solar Thermal Power Plants

2 1. INTRODUCTION

systems account for 45%e70% of the primary investment; the annual
mean efficiency of a concentration field is normally 58%e72%, so
research on the concentration process greatly influences the efficiency
and cost of the system.
Energy losses in the concentration process mainly include cosine,
reflection, air transmission, and receiver interception losses caused by
concentrator errors. In addition, the limits of working environmental
conditions and concentrator shelf life, while still ensuring
concentrator precision, mean that concentrator cost reductions now
face great restrictions. Considering both of these factors, it is
necessary to carry out in-depth research on the collection of optical
energy and high-precision concentration using aspects of optics,
mechanics, and materials science and overcome the influences of
concentrator mirror shape aberration and tracking errors on energy
flow transmission efficiency as well as the problem of low CSP system
conversion efficiency caused by spatial and temporal distribution of
the energy flux failing to satisfy the requirement of receiver; an
integrated design method of solar beam concentration and thermal
absorption based on the highly efficient energy flow transmission
must be established.
2. CSP system conversion efficiency and reliability of devices. When
the efficiency of an CSP system is increased by 1%, the levelized
cost of electricity from CSP generation will decrease by 8%, and the
corresponding total capital investment will be reduced by 5%e6%.
System efficiency has significant impacts on CSP system costs.
Future technical developments shall be mainly based on stable
operation of the system, improvements in system efficiency, and
development of major technical equipment techniques, system
integration techniques, equipment performance evaluation
methods and their respective testing platforms, technical
standards, and regulations in the large-scale CSP generation
system. Conventional thermal power conversion efficiency was
improved along with increases in the parameters of the working
medium, and the basic approach to improving the efficiency of the
cycle was to increase the temperature and pressure of the working
fluid. During CSP generation, however, the efficiency of solar
receiver system conversion decreases with increases in the
temperature of the heat transfer medium, which is also
accompanied by intensive unsteadiness in time, nonuniformness in
space, and transient strong energy flow impact. Therefore,
improvements in thermal power conversion efficiency shall not be
accomplished by completely relying on the regular thermal cycle,
and the laws of fluid flow and heat transfer processes are also
distinguished from regular ones. To greatly improve the efficiency,