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This work presents a Computer-Aided Molecular Design (CAMD) method for the synthesis and selection of binary working fluid mixtures used in Organic Rankine Cycles (ORC). The method consists of two stages, initially seeking optimum mixture performance targets by designing molecules acting as the first component of the binaries. The identified targets are subsequently approached by designing the required matching molecules and selecting the optimum mixture concentration. A multiobjective formulation of the CAMD-optimization problem enables the identification of numerous mixture candidates, evaluated using an ORC process model in the course of molecular mixture design. A nonlinear sensitivity analysis method is employed to address model-related uncertainties in the mixture selection procedure. The proposed approach remains generic and independent of the considered mixture design application. Mixtures of high performance are identified simultaneously with their sensitivity characteristics regardless of the em...

This work adopts the ECCs (exergy composite curves) approach to explore the potential for ORC (organic Rankine cycle) process improvements. The method is used to explore different ORC configurations supported by a mathematical model representing a generic multi-pressure ORC cascade and developed based on the principles of the ECCs method. The model facilitates interconnectivity at different temperature and pressure levels, also considering two types of turbines, namely an expansion and an induction turbine. It is employed to investigate the performance of two major ORC configurations, namely one considering independent pressure loops with an expansion turbine and the other considering pressure loops contacted through induction turbines. These configurations are updated with new features within an iterative procedure supporting the systematic identification of the optimum number of pressure loops together with several operating optimization parameters. The optimization is performed using an inclusive objective function, while the obtained results indicate ORC systems of high performance.

Abstract This work presents a Computer-Aided Molecular Design (CAMD) method for the synthesis and selection of binary working fluid mixtures used in Organic Rankine Cycles (ORC). The method consists of two stages, initially seeking optimum mixture performance targets by designing molecules acting as the first component of the binaries. The identified targets are subsequently approached by designing the required matching molecules and selecting the optimum mixture concentration. A multi-objective formulation of the CAMD-optimization problem enables the identification of numerous mixture candidates. A non-linear sensitivity analysis method is employed to address model-related uncertainties in the mixture selection procedure. The proposed approach remains generic and independent of the considered mixture design application.

Abstract This work investigates the performance of working fluid mixtures for use in solar ORC (Organic Rankine Cycle systems) with heat storage employing FPC (Flat Plate Collectors). Several mixtures are considered including conventional choices often utilized in ORC as well as novel mixtures previously designed using advanced computer aided molecular design methods (Papadopoulos et al., 2013). The impact of heat source variability on the ORC performance is assessed for different working fluid mixtures. Solar radiation is represented in detail through actual, hourly averaged data for an entire year. A multi-criteria mixture selection methodology unveils important trade-offs among several important system operating parameters and efficiently highlights optimum operating ranges. Such parameters include the ORC thermal efficiency, the net generated power, the volume ratio across the turbine, the mass flow rate of the ORC working fluid, the evaporator temperature glide, the temperature drop in the storage tank, the ORC total yearly operating duration, the required collector aperture area to generate 1 kW of power and the irreversibility. A mixture of neopentane – 2-fluoromethoxy-2-methylpropane at 70% neopentane is found to be the most efficient in all the considered criteria simultaneously.

This work presents a multi-level method for the design and selection of heat exchange working fluids tailored for Organic Rankine Cycle (ORC) systems used in power and/or heat cogeneration from renewable, low enthalpy sources. A systematic methodology is employed supporting the design of optimum working fluid candidates using Computer Aided Molecular Design (CAMD). The performance of the designed fluids is evaluated using ORC models that enable simulation and economic design optimization. In addition to chemical/physical properties the performed evaluation considers working fluid characteristics such as safety (toxicity and flammability) and environmental properties (ozone depletion potential and global warming potential) that are equally important to economic efficiency. The proposed approach is illustrated through a case study involving varying geothermal field conditions employed as energy sources for greenhouse power and heat co-generation.

Studies involving the design of interplant water networks have received significant attention over the past few years. Many methods have been developed to assist in obtaining efficient water reuse network design schemes, mainly using fundamental concepts of water integration. Our recent work has presented the importance of considering spatial constraints in the form of utility corridor availability, when identifying cost‐effective interplant water network arrangements in industrial zones (Alnouri et al., [2014]: Clean Technologies and Environmental Policy 16, 1637–1659). This article extends the scope of our previous work by enabling the identification of new corridor locations, which could potentially be used alongside existing utility infrastructure. We present an optimization framework that allows unutilized areas of land within industrial zones to be sectioned off and added as optional transportation channels, together with existing utility corridor regions, in the course of attaining cost‐effective interplant water network designs. The methodology entails that identification of optimal wastewater reuse schemes among various processing entities, by exploring options for enhanced utility corridors. As an illustration, several cases that utilize an assumed layout for an industrial zone have been carried out, in which a number of unutilized regions of land were identified to exist. Several opportunities that allow for potential corridor additions onto existing corridor infrastructure, through the exploitation of unutilized regions of land within the plot, were explored. A number of improvements in the water network designs obtained are highlighted for the different case scenarios that have been investigated, using the proposed approach. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1492–1511, 2016

Energy systems are undergoing rapid change as the world responds to climate change. Many policymakers may ask, what will be the next great energy source for a low-carbon future? All indications so far point to hydrogen energy. Although it is anticipated that costs will likely fall as the hydrogen production scale increases, it may be reported that the high technology costs remain a barrier to the widespread shift towards hydrogen. This paper presents hydrogen production costs for various production methods for different regions across the world, including the USA, the Middle East, Europe, India, and Canada. The costs of hydrogen production from biomass gasification, coal gasification, and natural gas reforming are compared, revealing the varying costs across different regions. Moreover, the production of green hydrogen from renewable energy sources is also presented, and compared with conventional methods. It highlights that while green hydrogen is environmentally sustainable, its production remains cost-intensive compared to integrated processes. Notably, the Middle East and India demonstrate the most economical production costs for both electrolysis and nuclear-based processes, while Europe shows the highest costs. The information presented in this paper could be helpful for researchers and policymakers to make informed decisions regarding the necessary aspects that still need to be investigated, to help with the transition into a hydrogen energy future.

A Large-size engineering single layer fuel cell (SLFC) consisting of a nano-structured Li0.4Mg0.3Zn0.3O2-delta/Ce0.8Sm0.2O2-delta (LMZSDC) composite with an active area of 25 cm(2) (6 cm x 6 cm x 0 ...