Photovoltaic (PV) system certifications and codes have been modified to allow 1,500 V products onto the market which facilitate the plant engineering, procurement, and construction; however, the codes inadequately address the increased hazards to people and equipment in a high-voltage, photovoltaic plant that emanate from the rapid release of thermal energy, pressure waves, and electromagnetic interference of an arc-fault event. Existing calculations can contradict one another and are rooted in theory, not in physical testing. For this investigation, a localized arc-plasma model for a cylindrical geometry arc was developed from coupled electrodynamic, thermodynamic, and fluid mechanics equations, that were convolved together based on previous arc-discharge models [1]. The model was developed to assess incident energy, used for determining appropriate personal protective equipment (PPE), as a function of spark-gap current. To validate the model, preliminary experiments were performed at Sandia National Laboratories (SNL) with voltage levels as high as 1,500 V. Further utility-scale PV experiments were also conducted with current levels as high as 1,607 A to provide further data. Arc-stability, plasma column spectral features and radiative temperature rise were all evaluated during each respective test to provide radiated power values for validation. Overall preliminary results suggest a logarithmic increase in radiative power between 250 and 2800 W/cm for a current increase from 100 to 300 A.
Field tests of air-copper arcs were completed at a high-voltage, photovoltaic power plant using a simplified, 'arc-in-a-box' geometry to study dc arc-faults. Copper electrodes, 12.7 mm in diameter, were arranged in three configurations and an arc was initiated using < 700 VDCwith applied energy varying from 40-3900 kJ. Constitutive modeling of the arc-discharge predicts arc temperatures much greater than 1000 K. Two diagnostic techniques were fielded to characterize the spectral and thermal emission. Optical emission spectroscopy determined the time-resolved and mean arc temperatures were approximately T_{mean}= 7500 with standard deviations of ± 600 K, and infrared (IR) imaging mapped the mean temperature field, T_{mean}=1500\ \mathrm{K}, of the arc-heated environment.
Field tests of air-copper arcs were completed at a high-voltage, photovoltaic power plant using a simplified, 'arc-in-a-box' geometry to study dc arc-faults. Copper electrodes, 12.7 mm in diameter, were arranged in three configurations and an arc was initiated using < 700 VDCwith applied energy varying from 40-3900 kJ. Constitutive modeling of the arc-discharge predicts arc temperatures much greater than 1000 K. Two diagnostic techniques were fielded to characterize the spectral and thermal emission. Optical emission spectroscopy determined the time-resolved and mean arc temperatures were approximately T_{mean}= 7500 with standard deviations of ± 600 K, and infrared (IR) imaging mapped the mean temperature field, T_{mean}=1500\ \mathrm{K}, of the arc-heated environment.
Photovoltaic (PV) system certifications and codes have been modified to allow 1,500 V products onto the market which facilitate the plant engineering, procurement, and construction; however, the codes inadequately address the increased hazards to people and equipment in a high-voltage, photovoltaic plant that emanate from the rapid release of thermal energy, pressure waves, and electromagnetic interference of an arc-fault event. Existing calculations can contradict one another and are rooted in theory, not in physical testing. For this investigation, a localized arc-plasma model for a cylindrical geometry arc was developed from coupled electrodynamic, thermodynamic, and fluid mechanics equations, that were convolved together based on previous arc-discharge models [1]. The model was developed to assess incident energy, used for determining appropriate personal protective equipment (PPE), as a function of spark-gap current. To validate the model, preliminary experiments were performed at Sandia National Laboratories (SNL) with voltage levels as high as 1,500 V. Further utility-scale PV experiments were also conducted with current levels as high as 1,607 A to provide further data. Arc-stability, plasma column spectral features and radiative temperature rise were all evaluated during each respective test to provide radiated power values for validation. Overall preliminary results suggest a logarithmic increase in radiative power between 250 and 2800 W/cm for a current increase from 100 to 300 A.
Sandia National Laboratories (SNL) National Solar Thermal Test Facility (NSTTF) and Tech Library have been collaborating over the course of the FY19 period to establish and maintain the first and only digital collection in the world of Concentrating Solar Power (CSP) related historical documents, dating back to the CSP program inception here at Sandia in the 1970's thru to the present. The unclassified, unrestricted (UUR) collection, comprised of internally generated Sandia documents as well as a significant number of external reports will be searchable via both the Sandia website and OSTI, DOE's document repository. DOE is currently championing efforts to get the collection launched, where international partners, which include Australia and Germany, plan to forward related documents to be included in the CSP archive. Advancing this transformative project will make the CSP collection accessible to the Sandia and global communities.
In this investigation a series of small-scale tests were conducted, which were sponsored by the Nuclear Regulatory Commission (NRC) Office of Nuclear Regulatory Research (RES) and performed at Sandia National Laboratories (SNL). These tests were designed to better understand localized particle dispersion phenomena resulting from electrical arcing faults. The purpose of these tests was to better characterize aluminum particle size distribution, rates of production, and morphology (agglomeration) of electrical arc faults. More specifically, this effort characterized ejected particles and high-energy dispersion, where this work characterized HEAF electrical characteristics, particle movement/distributions, and morphology near the arc. The results and measurements techniques from this investigation will be used to inform an energy balance model to predict additional energy from aluminum involvement in the arc fault. The experimental setup was developed based on prior work by KEMA and SNL for phase-to-ground and phase-to-phase electrical circuit faults. The small-scale tests results should not be expected to be scale-able to the hazards associated with full-scale HEAF events. Here, the test voltages will consist of four different levels: 480V, 4160V, 6900V and 10kV, based on those realized in nuclear power plant (NPP) HEAF events.
Further development of the Gen3 Liquid-Pathway project is necessary to address technical engineering challenges with respect to incorporation of a flow control valve and sodium system for the 2.0 MWth Pilot-Scale system. For the Thermal Transport development task 1.3, Sandia National Laboratories (SNL) originally set aside $\$$388,425 for the development of a heat trace test bed, however while the team felt that this work is necessary to de-risk a number critical design-related issues the team also has identified items that require more near-term attention. These items largely pertain to the Chloride molten salt values development, with operation up to 720°C, as well as operational mode/system design development as it pertains to the sodium system design, which is currently not included as part of the system design work. The Gen 3 project team requests the ~$\$$388k of funds be used to address these issues, where the previous work requested may be addressed with the 300kWth chloride molten salt loop. These funds would only be spent during the remainder of the Phase 1 budget period, in preparation of final design work for the Phase 2 portion of the project. For the Budget Summary below, please note that the values are burdened values and not raw values, so the actual values going to the entities will be less due to National Laboratory tax costs.
The primary objective of this report is to determine a viable pipe preheating system for a chloridesalt blend (40%MgCl2/20%NaCl/40%KCI) that can preheat the pipe to 450 °C and withstand a maximum exposure temperature of 740 °C. Preheating involves heating the pipe to a specific desired temperature, called preheat temperature, of the pipe. The temperature is maintained by heated molten salt flowing through the piping system. This report reviews 5-types of pipe preheating systems, of which three pipe preheating systems- MI cable, heat tape, and ceramic fiber heaters, were found to be viable for the Gen 3 Liquid Pathway application. The report reviews the pipe preheating efficiency of conduction verses radiant heat transfer. For each of the 5 types of pipe preheating systems, the report describes the system and addresses installation requirements, temperature control, reliability survey, and pre-construction verification testing for the most applicable preheating system. Under Appendix A, images from design drawings demonstrate pipe routing with the preheating system and insulation attached to the pipe along with pipe guides and pipe supports, as designed using Caesar II finite element analysis within the SNL NSTTF Solar Power Tower.
This specification provides to the supplier with requirements for design, manufacturing, inspection and testing in works and cleaning, painting, packing and protection for transport to site for the hot molten salt pumps, receiver circulation pumps and the attemperation molten salt pumps to be used at Sandia National Laboratories, Albuquerque, NM, NSTTF Solar Power Tower.
The primary objective of this report is to determine a viable pipe preheating system for a chloride-salt blend that can preheat the pipe to 450°C and withstand a maximum exposure temperature of 750°C. Preheating involves heating the pipe to a specific desired temperature, called preheat temperature, of the pipe. The temperature is maintained by heated molten salt flowing through the piping system. This report reviews 5-types of pipe preheating systems, of which three pipe preheating systems- MI cable, heat tape, and ceramic fiber heaters, were found to be viable for the Gen 3 Liquid Pathway application. The report reviews the pipe preheating efficiency of conduction verses radiant heat transfer. For each of the 5 types of pipe preheating systems, the report describes the system and addresses installation requirements, temperature control, reliability survey, and pre-construction verification testing for the most applicable preheating system. Under Appendix A, images from design drawings demonstrate pipe routing with the preheating system and insulation attached to the pipe along with pipe guides and pipe supports, as designed using Caesar II finite element analysis within the SNL NSTTF Solar Power Tower.
