scholarly journals Hydrogen monitoring in the heat transfer fluid of parabolic trough plants

2019 ◽  
Author(s):  
Christian Jung ◽  
Marion Senholdt ◽  
Carsten Spenke ◽  
Thomas Schmidt ◽  
Steffen Ulmer

2021 ◽  
Vol 321 ◽  
pp. 02016
Author(s):  
Belkacem Bouali ◽  
Hanane-Maria Regue

This paper presents an analysis of the performance of a parabolic trough collector (PTC) according to some key operating parameters. The effects of the secondary reflector, the length and thickness of the absorber tube (receiver tube) and the flow rate of the heat transfer fluid (HTF) are investigated. The main objective is to determine an optimal operation, which improves the performance of a traditional PTC. The target variables are the temperature at the outlet of the tube, the amount of energy collected by the HTF and the efficiency of the system. The solar flux data concern the city of LAGHOUAT located in the south of Algeria. Four days in different seasons are considered. The optical analysis of the system is performed by using the open source SolTrace code. The output of this analysis is used as a boundary condition for the CFD solver. The conjugate heat transfer and the fluid flow through the absorber tube are simulated by using ANSYS-CFX solver. Water is considered as heat transfer fluids. The obtained results show that the use of a curved secondary reflector significantly improves the performance of the traditional PTC. As the thickness of the tube increases, the heat storage in the material increases, which increases the temperature at the exit of the tube and therefore the efficiency of the system. However, the length of the tube depends on the mass flow of the HTF and vice versa. To keep the efficiency constant by choosing another length, it is necessary to choose a mass flow rate proportional to the flow rate corresponding to the initial length.





2003 ◽  
Vol 125 (2) ◽  
pp. 170-176 ◽  
Author(s):  
D. Kearney ◽  
U. Herrmann ◽  
P. Nava ◽  
B. Kelly ◽  
R. Mahoney ◽  
...  

An evaluation was carried out to investigate the feasibility of utilizing a molten salt as the heat transfer fluid (HTF) and for thermal storage in a parabolic trough solar field to improve system performance and to reduce the levelized electricity cost. The operating SEGS (Solar Electric Generating Systems located in Mojave Desert, California) plants currently use a high temperature synthetic oil consisting of a eutectic mixture of biphenyl/diphenyl oxide. The scope of this investigation included examination of known critical issues, postulating solutions or possible approaches where potential problems exist, and the quantification of performance and electricity cost using preliminary cost inputs. The two leading candidates were the so-called solar salt (a binary salt consisting of 60% NaNO3 and 40% KNO3) and a salt sold commercially as HitecXL (a ternary salt consisting of 48% CaNO32, 7% NaNO3, and 45% KNO3). Assuming a two-tank storage system and a maximum operation temperature of 450°C, the evaluation showed that the levelized electricity cost can be reduced by 14.2% compared to a state-of-the-art parabolic trough plant such as the SEGS plants. If higher temperatures are possible, the improvement may be as high as 17.6%. Thermocline salt storage systems offer even greater benefits.



2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Zhai Rongrong ◽  
Yang Yongping ◽  
Yan Qin ◽  
Zhu Yong

The thermal oil is applied as the heat transfer fluid in a solar parabolic trough collector system. Firstly, the system dynamic model was established and validated by the real operating data in typical summer and spring days in references. Secondly, the alteration characteristics of different solar radiation, inlet water temperature and flow rate, and collectors’ area and length are analyzed and compared with the normal working condition. The model can be used for studying, system designing, and better understanding of the performance of parabolic trough systems.



Author(s):  
Tugba S. Sensoy ◽  
Sam Yang ◽  
Juan C. Ordonez

In this paper we present a dynamic three-dimensional volume element model (VEM) of a parabolic trough solar collector (PTC) comprising an outer glass cover, annular space, absorber tube, and heat transfer fluid. The spatial domain in the VEM is discretized with lumped control volumes (i.e., volume elements) in cylindrical coordinates according to the predefined collector geometry; therefore, the spatial dependency of the model is taken into account without the need to solve partial differential equations. The proposed model combines principles of thermodynamics and heat transfer, along with empirical heat transfer correlations, to simplify the modeling and expedite the computations. The resulting system of ordinary differential equations is integrated in time, yielding temperature fields which can be visualized and assessed with scientific visualization tools. In addition to the mathematical formulation, we present the model validation using the experimental data provided in the literature, and conduct two simple case studies to investigate the collector performance as a function of annulus pressure for different gases as well as its dynamic behavior throughout a sunny day. The proposed model also exhibits computational advantages over conventional PTC models-the model has been written in Fortran with parallel computing capabilities. In summary, we elaborate the unique features of the proposed model coupled with enhanced computational characteristics, and demonstrate its suitability for future simulation and optimization of parabolic trough solar collectors.



Author(s):  
Andrea Giostri ◽  
Claudio Saccilotto ◽  
Paolo Silva ◽  
Ennio Macchi ◽  
Giampaolo Manzolini

The paper deals with the development and testing of an innovative code for the performance prediction of solar trough based CSP plants in off-design conditions. The code is developed in MS Visual Basic 6.0 with Excel as user interface. The proposed code originates from a previously presented algorithm for on-design sizing and cost estimation of the solar field lay-out, as well as of the main components of the plant, including connecting piping and the steam cycle. Off-design calculation starts from data obtained through the on-design algorithm and considers steady-state situations. Both models are implemented in the same software, named PATTO (PArabolic Trough Thermodynamic Optimization), which is very flexible: the optical-thermal model of collectors can simulate different kinds of parabolic trough systems in commerce, including a combination of various mirrors, receivers and supports. The code is also flexible in terms of working fluid, temperature and pressure range, and can also simulate direct steam generation plants (DSG). Regarding the power block, a conventional steam cycle with super-heater, eventually a re-heater section, and up to seven regenerative bleedings is adopted. The off-design model calculates thermal performance of collectors taking into account proper correlations for convective heat transfer coefficients, considering also boiling regime in DSG configurations. Solar plant heat and mass balances and performances at off-design conditions are estimated by accounting for the constraints imposed by the available heat transfer areas in heat exchangers and condenser, as well as the characteristic curve of the steam turbine. The numerical model can be used for a single calculation in a specific off-design condition, as well as for a whole year estimation of energy balances with an hourly resolution. The model is tested towards real applications and reference values found in literature; in particular, focusing on SEGS VI plant in the USA and SAM® code. Annual energy balances with ambient condition taken from TMY3 database are obtained, showing good accuracy of predicted performances. The code potentiality in the design process reveals twofold: it can be used for plant optimization in feasibility studies; moreover it is useful to find the best control strategy of a plant, especially the mass flow of heat transfer fluid in each operating condition.



2018 ◽  
Vol 220 ◽  
pp. 337-350 ◽  
Author(s):  
Chun Chang ◽  
Adriano Sciacovelli ◽  
Zhiyong Wu ◽  
Xin Li ◽  
Yongliang Li ◽  
...  


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