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In spite of the discontinuous nature of solar energy, concentrated solar power (CSP) plant with thermal energy can not only stabilize output but also be operated as a peak load regulation plant in a multi-energy system. This work demonstrates the dynamic characteristics of the key heat transfer components and thermal transport processes of a solar power tower (SPT) plant with thermal energy storage, which is operated under the disturbances of external environment and electricity demand. A 50MW commercial power tower plant is chosen as the study object. Detailed systematic dynamic models based on two modelling method of essential sub-systems are developed, implemented, and integrated into TRNSYS to improve the reliability of simulation as well as the prevision accuracy. The model is completed with a control strategy that regulates the water level in the evaporator efficiently. System-level simulation is conducted by two time scales, during a couple of minutes, and on a couple of hours. It is shown that the model can provide theoretical reference data for the unit operating characteristic analysis, predict the trend of the plant thermal characteristics. The thermal transport characteristics in the steam generation system and steam turbine have been revealed, which is useful for the study of regulatory mechanisms for a peak-shaving plant. [ABSTRACT FROM AUTHOR]

Plant developers of parabolic trough collector (PTC) systems for industrial steam generation face various challenges. Some of the main challenges are availability of land, buildings in the vicinity of the plant that cast shadows on the collectors as well as land restrictions. The typical north-south collector axis alignment in many cases may not be possible due to limits of available ground. These were challenges that were faced in the planning phase for installing a PTC plant on the premises of the KEAN Soft Drinks Ltd factory in Limassol, Cyprus. As these issues cannot be avoided they must be accounted for by the plant developer, especially when a performance guarantee is given. This work presents, amongst other things, factors that should be analysed in order to predict the energy yield in the planning phase as best as possible by using a simulation model. In the sensitivity study presented in this paper, several effects on the energy yield were investigated theoretically. These effects include: Tracking inaccuracy, non-parallel collector row axis orientations as well as north-south vs. east-west collector alignment. A dynamic simulation model developed by the Solar-Institut Jülich (SIJ) [1] was further developed and used for the analysis. The simulation model features a deviation between the measured and simulated oil temperature at the collector outlet of only 1.5 K (rms). The findings are presented in this paper and give an insight into the effectiveness of mid-sized PTC systems for the industry sector. [ABSTRACT FROM AUTHOR]

Dynamic modelling and simulation offers a way to investigate the transient behavior of thermal energy storage (TES) systems. Most modelling work presented in literature focuses only to sub-processes of a TES facility, especially, if the comparison against experimental data is included. In this study, we combine experimental and computational work, and aim at modelling and investigating the whole TES system. We share experiences gained and discuss results, including the experiments planning, modelling scope, measurement uncertainty, heat exchange, heat losses, calibration and validation. [ABSTRACT FROM AUTHOR]

Parabolic trough collector (PTC) systems are commercially available concentrating solar power plants widely known for their application to generate electrical power. To further reduce the dependency on fossil fuels, such systems can also be deployed for producing process heat for industrial purposes. In combination with a thermal energy storage system, this technology has the ability to reliably supply on-demand process heat. This paper gives details on a fully automated PTC system with concrete thermal energy storage (C-TES) and kettle-type boiler that supplies saturated steam for a beverage factory in Limassol, Cyprus. In the focus is the validation of a dynamic simulation model in Modelica® that physically describes the entire PTC system. The simulation model uses various plant data as inputs including mirror reflectivity and weather data from on-site measurements. The validation was carried out in three steps. First, the PTC was validated as a stand-alone component. A time-dependent inlet oil temperature vector was given as input and the outlet oil temperature was computed. The root mean square (rms) error between the measured to simulated outlet oil temperature values results in 3.86% (equivalent to about 1.9 K). The second part of the validation then considered a complete PTC oil cycle in PTC-and-boiler operation mode (without C-TES). In the simulation, both the PTC inlet and outlet oil temperatures were computed. The result is a deviation < 4.25 % (rms) between measured to simulated values. Finally, in the third step, the C-TES model was validated as a stand-alone component. The deviation between measurement and simulated values is < 5% compared to the design point. [ABSTRACT FROM AUTHOR]

The utilization of computer codes and simulation software is one of the fundamental aspects for the development of any kind of technology and, in particular, in CSP sector for researchers, energy institutions, EPC and others stakeholders. In that extent, several models for the simulation of CSP plant have been developed with different main objectives (dynamic simulation, productivity analysis, techno economic optimization, etc.), each of which has shown its own validity and suitability. Some of those models have been designed to study several plant configurations taking into account different CSP plant technologies (Parabolic trough, Linear Fresnel, Solar Tower or Dish) and different settings for the heat transfer fluid, the thermal storage systems and for the overall plant operating logic. Due to a lack of direct experience of Molten Salt Parabolic Trough (MSPT) commercial plant operation, most of the simulation tools do not foresee a suitable management of the thermal energy storage logic and of the solar field freeze protection system, but follow standard schemes. ASSALT, Ase Software for SALT csp plants, has been developed to improve MSPT plant's simulations, by exploiting the most correct operational strategies in order to provide more accurate technical and economical results. In particular, ASSALT applies MSPT specific control logics for the electric energy production and delivery strategy as well as the operation modes of the Solar Field in off-normal sunshine condition. With this approach, the estimated plant efficiency is increased and the electricity consumptions required for the plant operation and management is drastically reduced. Here we present a first comparative study on a real case 55 MWe Molten Salt Parabolic Trough CSP plant placed in the Tibetan highlands, using ASSALT and SAM (System Advisor Model), which is a commercially available simulation tool. [ABSTRACT FROM AUTHOR]

Operation and control of superconducting (SC) magnets in the fusion devices having tokamak configuration opens up the domain of varying peak thermal energy environment as a function of time, commensurate with the plasma pulses. The varied thermal energy environment, thus propagated to upstream of the cooling system, is responsible for the system level instability of the overall cryogenic system. The cryogenic distribution system, the regime of first impact point, therefore, has to be tuned so as to stay at the nearly stable zone of operation. The configuration of the cryogenic distribution system, considered in the present study, involves a liquid helium (LHe) bath as a thermal buffer, LHe submerged heat exchangers and cold circulator apart from the valves for implementations of the precise controls. The cold circulator supplies the forced flow supercritical helium, used for the cooling of SC magnets. The transients of the thermal energy pulses can be attenuated in the cryogenic distribution system by various methodologies. One of the adopted methodologies in the present study is with the precise speed control of the cold circulators. The adopted methodology is applied to various configurations of arrangements of internal components in the distribution system for obtaining system responses with superior attenuation of energy pulses. The process simulation approach, assumptions, considered inputs and constraints, process modeling with different configuration as well as results to accomplish the control scheme for the attenuation of the thermal energy pulses are described. [ABSTRACT FROM AUTHOR]