Performance model and annual yield comparison of parabolic-trough solar thermal power plants with either nitrogen or synthetic oil as heat transfer fluid

2014 ◽  
Vol 87 ◽  
pp. 238-249 ◽  
Author(s):  
Mario Biencinto ◽  
Lourdes González ◽  
Eduardo Zarza ◽  
Luis E. Díez ◽  
Javier Muñoz-Antón
Keyword(s):  
Heat Transfer ◽  
Power Plants ◽  
Thermal Power ◽  
Performance Model ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Thermal Power Plants ◽  
Parabolic Trough ◽  
Solar Thermal Power ◽  
Synthetic Oil

scholarly journals Thermal Modelling and Simulation of Parabolic Trough Receiver Tubes

2010 ◽  
Author(s):  
Markus Eck ◽  
Jan Fabian Feldhoff ◽  
Ralf Uhlig
Keyword(s):  
Power Plants ◽  
Thermal Power ◽  
Efficiency Factor ◽  
Heat Losses ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Thermal Power Plants ◽  
Parabolic Trough ◽  
Solar Thermal Power ◽  
Operation Conditions

Receiver tubes (or heat collecting elements — HCE) are a key component of parabolic trough solar thermal power plants. They are mounted in the focal line of the collectors, absorb the concentrated solar irradiance and transfer the absorbed energy to the heat transfer fluid flowing through them. During the design phase of the receiver tubes and for the performance prediction of solar thermal power plants it is helpful to derive their technical properties, like the thermal losses or the temperature field in the receiver tubes, from their physical and geometrical properties. For this purpose, several models have been developed in the past [1–3]. In this paper, the different existing models are presented, compared and assessed. It is found that a simple analytical model is a helpful tool for the fast prediction of the temperature distribution in the receiver tube. Furthermore, a 2-dimensional and a 3-dimensioanl model are compared regarding the heat losses of a HCE at different operation conditions. Both tools show a good agreement with available measurements. Finally with these tools the efficiency factor F′ is calculated that considers the heat losses of an irradiated receiver compared to that of an un-irradiated receiver. According to the performed calculations, the efficiency factor of parabolic trough receivers is higher than expected.

Detailed Modeling of Parabolic Trough Collectors for the Part Load Simulation of Solar Thermal Power Plants

2012 ◽  
Author(s):  
F. Zaversky ◽  
S. Bergmann ◽  
W. Sanz
Keyword(s):  
Heat Transfer ◽  
Power Plant ◽  
Power Plants ◽  
Thermal Power ◽  
Solar Thermal ◽  
Thermal Power Plants ◽  
Steam Generation ◽  
Parabolic Trough ◽  
Solar Thermal Power ◽  
Direct Steam

Solar thermal power plants are a promising way of providing clean renewable electric energy. These plants concentrate the incoming solar direct irradiation in order to heat up a heat transfer fluid. The collected thermal energy can be stored or instantly delivered to a power block where part of the thermal energy is converted to electrical energy in a turbine with the connected generator. The parabolic trough collector plant is the today’s most developed solar thermal power plant type. There the solar irradiation is focused on receiver tubes which are concentrically placed to the focal lines of the parabolic trough collectors. A high temperature oil is pumped through these receiver tubes, which collects the heat and delivers it later on to the steam generator of the connected Rankine steam cycle. In order to improve the efficiency of these solar thermal power plants, the direct steam generation (DSG) within the parabolic trough collector receiver tubes is being investigated. Both types of parabolic trough collectors, the conventional type using oil as heat transfer fluid and the direct steam generation type, are subject of this paper. A detailed steady-state parabolic trough collector model was developed for each type, using the thermodynamic simulation software IPSEpro. The developed models consider the cosine-loss attenuation factor, the shading attenuation factor, optical losses, as well as thermal losses. Appropriate heat transfer and pressure loss correlations were implemented for both collector types. For the direct steam generation model, distinct collectors for the preheating section, the evaporation section and the superheating section were used. Furthermore, the suitable length of discretization for the modeling of one collector loop within a center-fed solar field was investigated. Calculated solar field performance data for the oil concept were compared to validated data available in open literature. Finally, a power plant simulation with each collector type, over the course of one reference day, showed the great potential of the direct steam generation, as well as the suitability of IPSEpro for running solar thermal power plant yield simulations.

Comparison of Two Linear Collectors in Solar Thermal Plants: Parabolic Trough vs Fresnel

2011 ◽  
Author(s):  
A. Giostri ◽  
M. Binotti ◽  
P. Silva ◽  
E. Macchi ◽  
G. Manzolini
Keyword(s):  
Power Plants ◽  
Thermal Power ◽  
Solar Thermal ◽  
Heat Transfer Fluid ◽  
Steam Generation ◽  
Parabolic Trough ◽  
Research Activity ◽  
Optical Efficiency ◽  
Synthetic Oil ◽  
Yearly Average

Parabolic trough can be considered the state of the art for solar thermal power plants thanks to the almost 30 years experience gained in SEGS and, recently, Nevada Solar One plants in US and Andasol plants in Spain. One of the major issues that limits the wide diffusion of this technology is the high investment cost of the solar field and, particularly, of the solar collector. For this reason, since several years research activity has been trying to develop new solutions with the aim of cost reduction. This work compares commercial Fresnel technology with conventional parabolic trough plant based on synthetic oil as heat transfer fluid at nominal conditions and evaluates yearly average performances. In both technologies, no thermal storage system is considered. In addition, for Fresnel, a Direct Steam Generation (DSG) case is investigated. Performances are calculated by a commercial code, Thermoflex®, with dedicated component to evaluate solar plant. Results will show that, at nominal conditions, Fresnel technology have an optical efficiency of 67% which is lower than 75% of parabolic trough. Calculated net electric efficiency is about 19.25%, while parabolic trough technology achieves 23.6%. In off-design conditions, the gap between Fresnel and parabolic trough increases because the former is significantly affected by high radiation incident angles. The calculated sun-to-electric annual average efficiency for Fresnel plant is 10.2%, consequence of the average optical efficiency of 38.8%, while parabolic trough achieve an overall efficiency of 16%, with an optical one of 52.7%. An additional case with Fresnel collector and synthetic oil outlines differences among investigated cases. Finally, because part of performance difference between PT and Fresnel is simple due to different definitions, additional indexes are introduced in order to make a consistent comparison.

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