We demonstrated that adding nanoparticles to a molten salt would increase its utility as a thermal energy storage medium for a concentrating solar power system. Specifically, we demonstrated that we could increase the specific heat of nitrate and carbonate salts containing 1% or less of alumina nanoparticles. We fabricated the composite materials using both evaporative and air drying methods. We tested several thermophysical properties of the composite materials, including the specific heat, thermal conductivity, latent heat, and melting point. We also assessed the stability of the composite material with repeated thermal cycling and the effects of adding the nanoparticles on the corrosion of stainless steel by the composite salt. Our results indicate that stable, repeatable 25-50% improvements in specific heat are possible for these materials. We found that using these composite salts as the thermal energy storage material for a concentrating solar thermal power system can reduce the levelized cost of electricity by 10-20%. We conclude that these materials are worth further development and inclusion in future concentrating solar power systems.

No abstract

Large vapor cloud explosions (VCEs) and deflagration to detonation transition (DDT) events are of considerable interest to the petroleum refining and chemical processing industries. A detonation results in a very high flame speed and can significantly increase explosion energy and decrease standoff distance, increasing the blast load. Potential mitigation options to limit VCE severity include multiple simultaneous ignition sources to limit flame travel distance, suppressants to limit flame speed, and controlling the congested volume geometry to limit the flame travel distance. Another approach is minimizing the flame travel distance to free vent. Some VCE blast load prediction methods consider flame travel distance within a congested volume, but not the distance to free vent (D FV ). Decreasing the D FV limits flame acceleration and decreases the potential for a DDT. High fuel reactivities and elevated congestion/confinement levels require smaller distances to free vent. This paper describes a test program to demonstrate this mitigation option using near-stoichiometric ethylene-air mixtures in an elongated test rig configured with a medium level of congestion to determine the free vent distance required to prevent a DDT. Test program results, associated Flame Acceleration Simulator predictions, and potential areas for future research are included.

Hydrogen is a key energy carrier for modern society. The breaking of the hydrogen bonds within traditional hydrocarbon molecules has been the primary mode of energy utilization since the industrial revolution. An increased focus on "net-zero" greenhouse gas emissions, specifically carbon dioxide and methane, has resulted in a global push for lower carbon energy vectors, including pure hydrogen. Accurately modeling the dispersion, fire, and explosion hazards associated with new and existing hydrogen production, distribution and transportation networks, and consumption is a key component to the safe expansion of these networks. BakerRisk performed a series of very lean hydrogen-air vapor cloud explosion (VCE) tests as part of an internal research effort. The goal of these tests was to better understand the VCE hazards associated with very lean hydrogen-air mixtures (≤14% H 2 ). Flame speeds and blast loads were measured using high-speed video and an array of dynamic pressure transducers. This paper discusses the test setup and test results, including a comparison with data from prior tests. The measured flame speeds are compared to those predicted using computational fluid dynamics analysis and referenced to deflagrationto-detonation criteria. Discussion regarding the application of these test results to facility siting studies is also provided.