Solar Field Layout and Aimpoint Strategy Optimization

A real case study of an energy system based on a Solar Assisted Heat Pump (SAHP) fed by hybrid photovoltaic-thermal solar panels (PVT) and seasonal storage (SS) is presented in this paper. Exergy and exergy cost analyses are proposed as complementary methods for the assessment and better understanding of the efficiency of this cogeneration solar configuration. The system performance takes advantage of storage heat in summer, when the solar resource is high in Spain, and is then later consumed during the cold winter (heating season). The building is devoted to social housing, and it is currently under construction. The assessment is based on simulations developed using TRNSYS, a dynamic simulation software for energy systems. Results show that the unit exergy cost of the solar field is around 6. The cost of the seasonal storage is higher, about 13, and its formation is affected both by its own irreversibility and by the irreversibility of the PVT solar field. The cost of the heat delivered by the heat pump is around 15, being affected by all the upstream units and even by the grid. Besides, the analysis points out strategies for improving the system efficiency, such as increasing the size of the storage tank or improving the control strategy of the boiler.

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Shadow variation on photovoltaic collectors in a solar field

2004 23rd IEEE Convention of Electrical and Electronics Engineers in Israel ◽

10.1109/eeei.2004.1361164 ◽

2004 ◽

Cited By ~ 8

Author(s):

D. Weinstock ◽

J. Appelbaum

Keyword(s):

Solar Field

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Design Point for Predicting Year-Round Performance of Solar Parabolic Trough Concentrator Systems

ASME 2013 7th International Conference on Energy Sustainability ◽

10.1115/es2013-18055 ◽

2013 ◽

Author(s):

Men Wirz ◽

Matthew Roesle ◽

Aldo Steinfeld

Keyword(s):

Operating Conditions ◽

Transfer Model ◽

Parabolic Trough ◽

Specific System ◽

Simple Method ◽

Operating Condition ◽

Average Efficiency ◽

Design Point ◽

Yearly Average ◽

Solar Field

Thermal efficiencies of the solar field of two different parabolic trough concentrator (PTC) systems are evaluated for a variety of operating conditions and geographical locations, using a detailed 3D heat transfer model. Results calculated at specific design points are compared to yearly average efficiencies determined using measured direct normal solar irradiance (DNI) data as well as an empirical correlation for DNI. It is shown that the most common choices of operating conditions at which solar field performance is evaluated, such as the equinox or the summer solstice, are inadequate for predicting the yearly average efficiency of the solar field. For a specific system and location, the different design point efficiencies vary significantly and differ by as much as 11.5% from the actual yearly average values. An alternative simple method is presented of determining a representative operating condition for solar fields through weighted averages of the incident solar radiation. For all tested PTC systems and locations, the efficiency of the solar field at the representative operating condition lies within 0.3% of the yearly average efficiency. Thus, with this procedure, it is possible to accurately predict year-round performance of PTC systems using a single design point, while saving computational effort. The importance of the design point is illustrated by an optimization study of the absorber tube diameter, where different choices of operating conditions result in different predicted optimum absorber diameters.

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Development of an Innovative Code for the Design of Different Parabolic Trough Solar Fields

ASME 2009 3rd International Conference on Energy Sustainability, Volume 2 ◽

10.1115/es2009-90459 ◽

2009 ◽

Cited By ~ 3

Author(s):

Ennio Macchi ◽

Giampaolo Manzolini ◽

Paolo Silva

Keyword(s):

Solar Energy ◽

Energy Demand ◽

Working Fluid ◽

Fluid Temperature ◽

Parabolic Trough ◽

High Solar Radiation ◽

Power Block ◽

The Usa ◽

Solar Field ◽

Steam Cycle

The role of renewable energies and in particular solar energy could be fundamental in future scenarios of worldwide increase of energy demand: thermodynamic solar energy can play an important role in country with high solar radiation. This paper discusses the development and testing of an innovative code for the prediction of thermodynamic performances at nominal conditions and the estimation of costs of the whole plant, for different parabolic trough solar fields. The code allows a preliminary design of the solar field lay-out, the sizing of the main components of the plant and the optimization of the steam cycle. The code, named PATTO (PArabolic Trough Thermodynamic Optimization), allows to separately calculate the thermal efficiency of (i) parabolic trough systems in commerce as well as (ii) combination of components of various commercial systems, in order to exploit different technology solutions: combination of mirrors, receivers and supports. Using the selected parabolic troughs, the plant configuration is then completed by connecting pipes, heat exchangers, the steam cycle, and storage tanks. The code is also flexible in terms of working fluid, temperature and pressure range. Regarding the power block, a conventional steam cycle with super-heater and re-heater sections and up to seven regenerative bleedings is adopted. It is possible to use also simpler configuration as without re-heater or with less regenerative bleedings. Moreover, thanks to simple or sophisticated economic correlations depending on available data, the code calculates the overall investment cost for the considered solar field and the power block. The code performs steady state analysis at nominal conditions, while future developments are planned regarding part load analysis and transient simulations. The model is tested towards real applications and reference values found in literature; in particular, focusing on SEGS VI plant in the USA. Detailed results showing code potentiality, are presented in terms of solar field and power block energy balances, plant auxiliaries, piping and economic analysis.

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Solar Field Output Temperature Optimization Using a MILP Algorithm and a 0D Model in the Case of a Hybrid Concentrated Solar Thermal Power Plant for SHIP Applications

Energies ◽

10.3390/en14133731 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3731

Author(s):

Simon Kamerling ◽

Valéry Vuillerme ◽

Sylvain Rodat

Keyword(s):

Mass Flow Rate ◽

Mass Flow ◽

Flow Rate ◽

Solar Thermal ◽

Outlet Temperature ◽

Field Mass ◽

Heat Demand ◽

Process Heat ◽

Solar Field ◽

Control Trajectory

Using solar power for industrial process heat is an increasing trend to fight against climate change thanks to renewable heat. Process heat demand and solar flux can both present intermittency issues in industrial systems, therefore solar systems with storage introduce a degree of freedom on which optimization, on a mathematical basis, can be performed. As the efficiency of solar thermal receivers varies as a function of temperature and solar flux, it seems natural to consider an optimization on the operating temperature of the solar field. In this paper, a Mixed Integer Linear Programming (MILP) algorithm is developed to optimize the operating temperature in a system consisting of a concentrated solar thermal field with storage, hybridized with a boiler. The MILP algorithm optimizes the control trajectory on a time horizon of 48 h in order to minimize boiler use. Objective function corresponds to the boiler use, for completion of the heat from the solar field, whereas the linear constraints are a simplified representation of the system. The solar field mass flow rate is the optimization variable which is directly linked to the outlet temperature of the solar field. The control trajectory consists of the solar field mass flow rate and outlet temperature, along with the auxiliary mass flow rate going directly to the boiler. The control trajectory is then injected in a 0D model of the plant which performs more detailed calculations. For the purpose of the study, a Linear Fresnel system is investigated, with generic heat demand curves and constant temperature demand. The value of the developed algorithm is compared with two other control approaches: one operating at the nominal solar field output temperature, and the other one operating at the actual demand mass flow rate. Finally, a case study and a sensitivity analysis are presented. The MILP’s control shows to be more performant, up to a relative increase of the annual solar fraction of 4% at 350 °C process temperature. Novelty of this work resides in the MILP optimization of temperature levels presenting high non-linearities, applied to a solar thermal system with storage for process heat applications.

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Annual Yield Analysis of Solar Tower Power Plants With GREENIUS

Journal of Solar Energy Engineering ◽

10.1115/1.4004355 ◽

2011 ◽

Vol 133 (3) ◽

Cited By ~ 16

Author(s):

Jürgen Dersch ◽

Peter Schwarzbözl ◽

Timo Richert

Keyword(s):

Renewable Energy ◽

Power Plants ◽

Software Tool ◽

Parabolic Trough ◽

Concentrating Solar Power ◽

Solar Field ◽

Performance Calculation ◽

Design Power ◽

Energy Plants ◽

Renewable Energy Plants

An existing software tool for annual performance calculation of concentrating solar power and other renewable energy plants has been extended to enable the simulation of solar tower power plants. The methodology used is shown and a demonstrative example of a 50 MWe tower plant in southern Spain is given. The influence of design power and latitude on solar field layout is discussed. Furthermore, a comparison of the tower plant with a 50 MWe parabolic trough and a Linear Fresnel plant at the same site is given.

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The application of the Whitehead theory of relativity to non-static, spherically symmetrical systems

Proceedings of the Royal Society of London Series A - Mathematical and Physical Sciences ◽

10.1098/rspa.1954.0092 ◽

1954 ◽

Vol 222 (1151) ◽

pp. 509-526 ◽

Cited By ~ 6

Keyword(s):

Theory Of Relativity ◽

General Theory Of Relativity ◽

Current Standard ◽

World Model ◽

Basic Principles ◽

Density Distributions ◽

Free Particles ◽

Static Systems ◽

Solar Field ◽

Good Agreement

In a recent paper Synge (1952) reformulated in current standard notation the basic principles of the theory of relativity of A. N. Whitehead and investigated the gravitational properties of a spherically symmetrical static distribution of matter. He applied this theory to the solar field and verified the result previously indicated by Whitehead (1922) that the theory is in good agreement with the local tests satisfied by Einstein’s general theory of relativity. The present paper extends the theory of Whitehead to non-static systems whose velocity and density distributions possess complete spherical symmetry about a spatial origin in a Galilean frame of reference. In particular, a uniformly expanding homogeneous world-model is constructed which differs significantly both from Milne’s model and that of special relativity. The motion of free particles and photons in this model is investigated and a formula for the law of red-shifts is derived.

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Heat Flux Distribution Over a Solar Central Receiver Using an Aiming Strategy Based on a Conventional Closed Control Loop

ASME 2017 11th International Conference on Energy Sustainability ◽

10.1115/es2017-3615 ◽

2017 ◽

Cited By ~ 2

Author(s):

Jesús García ◽

Yen Chean Soo Too ◽

Ricardo Vasquez Padilla ◽

Rodrigo Barraza Vicencio ◽

Andrew Beath ◽

...

Keyword(s):

Heat Flux ◽

Flux Distribution ◽

Thermal Stresses ◽

Control Strategies ◽

Multiple Input Multiple Output ◽

Control Loop ◽

Heat Flux Distribution ◽

Input Multiple Output ◽

Solar Receiver ◽

Solar Field

Solar thermal towers are a maturing technology that have the potential to supply a significant part of energy requirements of the future. One of the issues that needs careful attention is the heat flux distribution over the central receiver’s surface. It is imperative to maintain receiver’s thermal stresses below the material limits. Therefore, an adequate aiming strategy for each mirror is crucial. Due to the large number of mirrors present in a solar field, most aiming strategies work using a data base that establishes an aiming point for each mirror depending on the relative position of the sun and heat flux models. This paper proposes a multiple-input multiple-output (MIMO) closed control loop based on a methodology that allows using conventional control strategies such as those based on Proportional Integral Derivative (PID) controllers. Results indicate that even this basic control loop can successfully distribute heat flux on the solar receiver.

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