Previous work done in the area of trough type CSP technology can be divided into three categories: (i) general power plant’s performance modeling; (ii) HCE modeling and
experiments; (iii) Storage system operating modeling and simulation. The following section on general power plant performance modeling addresses studies conducted to provide a method to estimate the annual electricity generation and lifetime LCOE in different locations and varying site configurations. HCE modeling and experiments discuss the work done by researchers who used models and experiment to predict the performance characters of HCE. Storage modeling describes the prediction of working conditions of two-tank and thermocline thermal energy storage systems. Literature pertaining to experimental work is not addressed as the proposed work primarily related to numerical modeling.
1.3.1 General Power Plant Performance Modeling
The most widely used model to simulate CSP plant – The System Advisor Model (SAM) is being developed by the National Renewable Energy Laboratory (NREL) and the Department of Energy (DOE) since 2003[29]. The first version was published in 2007 and several new versions were published thereafter. It is a software package capable of simulating several kinds of alternative energy systems. For CSP, SAM makes
performance prediction by empirical or physical modeling in its latest version. The program is used to calculate the cost of electricity based on information including the project location, system specifications, installation and operating costs, financing configuration, applicable tax credits, and incentives.
Other than SAM, several proprietary parabolic trough type CSP plant’s performance simulation programs have been developed. The operating company of SEGS developed
an hourly based simulation program specific to its plant to estimate the performance and fulfill its own need [30].Flabeg Solar International (FSI) developed a performance simulation model to conduct design studies and advertise CSP plants [31]. Also, the German Aerospace Center has established a solar power performance model [32]. However, all of these simulation programs are confidential and not disclosed.
1.3.2 HCE Model and Experiments
Research in the solar field of CSP focuses primarily on HCEs and concentrating troughs, since trough modeling is mainly focusing on designing, structure strength and reflection, this literature review will concentrate on HCE models.
Several models have been developed since 1970. Ratzel, et al. established an analytical and numerical receiver model to simulate receiver’s conductive and convective heat losses [33]. Thomas, et al. developed a set of regression equations based on the result of a numerical heat transfer model [34]. Forristall accomplished a detailed numerical model to estimate the heat transfer of receivers [22]. Garcia-Valladares, et al. developed a detailed numerical model with three dimensional heat transfer analysis [35]. Odeh and his grounp’s research include predicting the thermal performance of a collector which used water instead of oil to absorb the collected thermal energy. Also, they developed a model to study the performance variation caused by adjusting the field arrangements under Australian conditions [36, 37].Ricardo, et al. developed a one dimensional numerical model which considers the thermal interaction between the neighboring surfaces [38].
Several experimental results are also available for reference. Ulf Herrmann provided the experimental performance of the SKAL-ET collectors, which were used in the Andasol- 1 power plant [39]. F. Nburkholder, et al. published detailed heat loss testing results of the PTR70 Parabolic Trough Receiver [40].
1.3.3 Storage Model
Research in storage system focuses on improving TES’ performance, and reducing the system’s cost. Also, some papers discuss storage system’s heat loss characteristics during operation.
Ulf Herrmann developed a regression empirical heat loss model from measured data for two tanks system [41]. Joseph E. Kopp used constant heat loss values in his thesis [42]. And the SAM program used fixed heat loss values or results from a zero dimension model for empirical or physical type simulations. These results indicate that the heat loss is relatively small in comparison with the stored thermal energy, and can be neglected from rough calculation.
1.3.4 Cost Model
Previous research in the cost analysis of CSP plant mainly emphasizes its three systems: solar field system, storage system, and power block system. H. price used scaling equations to estimate the cost for the solar field [29]. Documentation of SAM program published a linear or linear like method to estimate the price for CSP plant, and showed a detailed budget list for a purposed 110MW CSP plant in State of Arizona [43]. B. Kelly, et al. estimated the cost of a two-tank thermal storage system by summing up material
and labor costs [44]. Sargent & Lundy LLC Consulting Group developed a regression model from previous data to estimate the unit electricity cost for power blocks [45].
1.3.5 Net Energy Analysis of CSP plant
Previous research in the net energy analysis of CSP plant primarily concentrated on determining whether it's an energy sink or producer, and comparing the energy returns from different alternative energies. Teresita Larrain conducted a net energy analysis of hybrid CSP plants in Chile [46]. A comparative analysis of energy cost between photovoltaic, concentrating solar, and wind electricity generation was conducted by Michael Dale [47].Charles A. S. Hall also performed lifetime analysis and compared the energy return among traditional fossil and alternative energies [48]. For standalone CSP, though some rough estimated energy return data are available, no known detailed and comprehensive analysis has been performed, and no result is disclosed.