A Performance-Based Approach to Quantify Atmospheric River Flood Risk

Atmospheric rivers (ARs) are a class of meteorologic phenomena that cause significant precipitation and flooding on the US West Coast. This work presents a new Performance-based Atmospheric River Risk Analysis (PARRA) framework that adapts existing concepts from probabilistic risk analysis and performance-based engineering for application in the context of AR-driven fluvial flooding. The PARRA framework is a chain of physically based models that link the atmospheric forcings, hydrologic impacts, and economic consequences of AR-driven fluvial flood risk together at consistent “pinch point” variables. Organizing around these pinch points makes the framework modular, in that models between pinch points can be updated without affecting the rest of the model chain, and it produces a probabilistic result that quantifies the uncertainty in the underlying system states. The PARRA framework can produce results beyond analyses of individual scenario events and can look towards prospective assessment of events or system changes that have not been seen in the historic record. The utility of the PARRA framework is demonstrated through a series of analyses in Sonoma County, California. Evaluation of a February 2019 case study AR event shows that the individual component models produce simulated distributions that capture the observed precipitation, streamflow, inundation, and damage. The component models are then run in sequence to generate a first-of-its-kind AR flood loss exceedance curve for Sonoma County. The prospective capabilities of the PARRA framework are presented through the evaluation of a hypothetical mitigation action. It was found elevating 150 homes, selected based on their proximity to the Russian River, was able to reduce the average annual loss by half. The loss results from the mitigated building portfolio are compared against the original case. While expected benefits were minimal for the smallest events, the larger, more damaging ARs were expected to see loss reductions of approximately $50 million per event. These results indicate the potential of the PARRA framework for examining other changes to flood risk at the community level, including future changes to the hazard, through climate change; exposure, through development; and/or vulnerability, through flood mitigation investments.

Optimization of ORC Power Plants for Geothermal Application in Kenya by Combining Exergy and Pinch Point Analysis

Geothermal energy is a sustainable renewable source of energy. The installed capacity of geothermal energy in Kenya is 847.4 MWe of the total 2.7 GWe. This paper presents the effect of six different working fluids to optimize the geothermal of 21.5 MWe of reinjected brine at a single-flash power plant in Kenya. Engineering Equation Solver (EES) code was used to design and optimize simple organic Rankine (ORC) and regenerative cycles. The objective was to combine pinch point analysis and exergy analysis for the optimum utilization of geothermal energy by varying the turbine inlet pressure, pinch point, and reinjection temperature. The turbine inlet pressures, and pinch points were varied to obtain optimum pressures for higher net power output and exergy efficiencies. As the pressure increased, the efficiencies and net power generated increase to optimal at turbine inlet pressures between 2000 and 3000 kPa. By maintaining a condenser temperature at 46.7 °C, the turbine outlet pressures were 557.5 kPa for isobutene, 627.4 kPa for isobutane, 543.7 kPa for butene, 438.9 kPa for trans-2-butene, 412.3 kPa for R236ea, and 622.9 kPa for R142b. For the pinch point of 10 °C, the working fluid with a lower net power is trans-2-butene at 5936 kW for a flow rate of 138.8 kg/s and the highest reinjection at 89.05 °C. On the other hand, R236ae had a flow rate of 398.2 kg/s, a higher power output of 7273 kW, and the lowest reinjection temperature of 73.47 °C for a 5 °C pinch point. In the pinch point consideration, the suitable fluid will depend on the best reinjection temperatures. The pinch point affects the heat transfer rates and effectiveness in the heat exchangers. The best pinch point is 10 °C, since the reinjection temperatures are the highest between 83 and 89 °C. The analysis showed that for unlimited reinjection temperatures, basic ORC is suitable. The regenerative cycle would be best suited where reinjection temperature is constrained by brine geochemistry.

Dislocation of the first metatarsophalangeal joint concomitant with Lisfranc joint dislocation in a 45-year-old man

A 45-year-old man presented with severe pinch-point crush injury to his left foot. Plain radiographs revealed dislocation of the first metatarsophalangeal joint and dorsolateral dislocation of the basal phalanx and sesamoids. The first tarsometatarsal joint was subluxed in the plantar direction and the second to fourth tarsometatarsal joints were subluxed dorsally. The sesamoids were displaced dorsolateral to the metatarsal head. There was a longitudinal tear of the joint capsule at the medial margin of the medial sesamoid, which was sutured together with the abductor hallucis tendon and collateral ligament. The Lisfranc and dorsal ligaments in the tarsometatarsal joint were torn and repaired after reduction and fixed with a plate. One year after surgery, there was contracture of the first metatarsophalangeal joint, but the patient had no pain and was able to run.

Using a Partially Evaporating Cycle to Improve the Volume Ratio Problem of the Trilateral Flash Cycle for Low-Grade Heat Recovery

This study examined the trilateral flash cycle characteristics (TFC) and partially evaporating cycle (PEC) using a low-grade heat source at 80 °C. The evaporation temperature and mass flow rate of the working fluids and the expander inlet’s quality were optimized through pinch point observation. This can help advance methods in determining the best design points and their operating conditions. The results indicated the partially evaporating cycle could solve the high-volume ratio problem without sacrificing the net power and thermal efficiency performance. When the system operation’s saturation temperature decreased by 10 °C, the net power, thermal efficiency, and volume ratio of the trilateral flash cycle system decreased by approximately 20%. Conversely, with the same operational conditions, the net power and thermal efficiency of the partially evaporating cycle system decreased by only approximately 3%; however, the volume ratio decreased by more than 50%. When the system operating temperature was under 63 °C, each fluid’s volume ratio could decrease to approximately 5. The problem of high excessive expansion would be solved from the features of the partially evaporating cycle, and it will keep the ideal power generation efficiency and improve expander manufacturing.

Integration of Low-Grade Heat from Exhaust Gases into Energy System of the Enterprise

In the paper is presented the way of Process Integration application for waste heat utilisation from exhaust gases streams with partial condensation. It is based on the construction of Hot Composite Curve representing the gaseous mixture cooling with accounting for the gas-liquid equilibrium of condensable vapour part. With Cold Composite Curve for streams requiring heating, the Pinch Point is determined. Then the structure of Heat Exchanger Network (HEN) for utilised Heat Integration into the energy system of the factory is developed accounting for the possible splitting of two-phase flow on gas and liquid streams and selection of plate heat exchanger (PHE) types for specific positions in HEN. The method is illustrated by a case study of heat utilisation from exhaust gases after superheated steam tobacco drying and flue gases from natural gas-fired boiler. The heat transfer areas of PHEs in HEN are optimised with the total annualised cost as an objective function. The payback period of the received solution is less than four months with a substantial saving of energy, reduction of greenhouse gases and other harmful emissions of combustion processes.

Heat integration applied on low thermal energy system: Building complex case study

The tertiary-building sector is one of the most important energy consumers in the Morocco, especially thermal energy. Its intensive use of energy is highly related to the building’s inefficient processes. The Moroccan strategy for energy efficiency aims mainly to save 12% of energy consumption by 2020 and 15% by 2030, which reinforce the appearance of many energy saving alternatives ranging from sensitization and construction laws to engineering applications. The present paper addresses the problem of the building complex energy efficiency in order to improve its performance thermally. The proposed approach in this work is based on the pinch technology which is a technique widely used to integrate and optimize the energy of thermal systems and which has demonstrated its successfulness for industrial process. The simulation results reveals that the potential thermal energy saving reaches 21.16%, with heat exchange network design initially proposed to clearly show the potential recovered. Based on the composite curves (CCs), the problem table algorithm (PTA) and the grand composite curve (GCC), the pinch point temperature is turned out to be 15°C with 316,99 kW of hot utility. The obtained results reveal that the proposed pinch technology perform its effectiveness not only in the industrial sector but also in the building-tertiary.

INFLUENCE OF EXTERNAL FORCE FACTORS ON THE STRENGTH OF UNIFORMLY LOADED CONSOLE-FIXED PARTS SUBJECT TO ABRASIVE WEAR

The intensity of wear observed in the working parts of machines operating in an abrasive environment largely determines their service life. However, in a number of cases, the downtime of equipment is associated with fractures of the operating elements casued by their abrasion. In this case, the operational state of the product is determined by the tolerable stresses. Theoretical studies on fi nding the mathematical relationships connecting wear and tolerable stresses are thus relevant. In addition, they are general and can be applied to various materials: metal, polymer, and composite ones. The goal of the present research is to make a theoretical study of the infl uence of external force factors on the strength of cantilever-fi xed parts of various geometric shapes in the process of their abrasive wear during the period of operation under uniform loading. In other words, the authors seek to determine the theoretical value of the limiting wear of a part according to the tolerable stresses. As a result of the study, a mathematical expression was obtained to establish the relationship between the maximum tolarable stresses and the value of the limiting wear of a cantilever-fi xed part under uniform loading. This relationship is necessary to analyse the values of the maximum tensile stresses in its sections. It has been established that the maximum tensile stresses are characteristic of the pinch point of the beam, regardless of its shape.