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Industrial producers face the task of optimizing production process in an attempt to achieve the desired quality such as mechanical properties with the lowest energy consumption. In industrial carbon fiber production, the fibers are processed in bundles containing (batches) several thousand filaments and consequently the energy optimization will be a stochastic process as it involves uncertainty, imprecision or randomness. This paper presents a stochastic optimization model to reduce energy consumption a given range of desired mechanical properties. Several processing condition sets are developed and for each set of conditions, 50 samples of fiber are analyzed for their tensile strength and modulus. The energy consumption during production of the samples is carefully monitored on the processing equipment. Then, five standard distribution functions are examined to determine those which can best describe the distribution of mechanical properties of filaments. To verify the distribution goodness of fit and correlation statistics, the Kolmogorov-Smirnov test is used. In order to estimate the selected distribution (Weibull) parameters, the maximum likelihood, least square and genetic algorithm methods are compared. An array of factors including the sample size, the confidence level, and relative error of estimated parameters are used for evaluating the tensile strength and modulus properties. The energy consumption and N2 gas cost are modeled by Convex Hull method. Finally, in order to optimize the carbon fiber production quality and its energy consumption and total cost, mixed integer linear programming is utilized. The results show that using the stochastic optimization models, we are able to predict the production quality in a given range and minimize the energy consumption of its industrial process.

Researchers have been driven to investigate sustainable alternatives to cement production, such as geopolymers, due to the impact of global warming and climate change resulting from greenhouse gas emissions. Currently, they are exploring different methods and waste materials to enhance the mechanical and physical properties of geopolymer and expand its application range. This review paper offers a thorough analysis of the utilization of various waste materials in geopolymer manufacturing and shows the creative contribution of this research to the development of environmentally friendly cement substitutes. The article covers the properties, durability, and practical applications of geopolymer composites made from various waste binders. It includes a microstructure and chemical analysis. The research findings indicate that geopolymers are an effective cementitious binder substitute for cement in various applications. Additionally, the ecological and carbon footprint analysis highlights the sustainability of geopolymers compared to cement.

Abstract Office buildings consume a significant amount of energy that can be reduced through behavioral change. Gamification offers the means to influence the energy consumption related to the activities of the office users. This paper presents a new mobile gamification platform to foster the adoption of energy efficient behaviors in office buildings. The gamification platform is a mobile application with multiple types of dashboards, such as (1) an information dashboard to increase the awareness of the users about their energy consumption and footprint, (2) a gaming dashboard to engage users in real-time energy efficiency competitions, (3) a leaderboard to promote peer competition and comparison, and (4) a message dashboard to send tailor-made messages about energy efficiency opportunities. The engagement and gamification strategies embedded in these dashboards exploit economic, environmental, and social motivations to stimulate office users to adopt energy efficient behaviors without compromising their comfort and autonomy levels. The gamification platform was demonstrated in an office building environment. The results suggest electricity savings of 20%.

Abstract Real-Time and Dynamic Thermal Ratings have been discussed in the literature as potential methods to increase network headroom, typically to allow the connection of distributed generators, mitigating the need for network reinforcement. The work presented in this paper considers the effectiveness of these techniques in terms of possible consumer connections as opposed to generation. A generalized temperature sensitive load modelling procedure is presented in order to derive representative demand group time-series profiles, and as such model the possible connections across the entire seasonal cycle. The procedure has been tested against real-world data taken from a rural 20 kV feeder in the North of England detailing the period October 2013–October 2014. This work was carried out as part of the LCNF funded Customer-Led Network Revolution (CLNR) smart grid project.

Abstract This paper explores the issues related to regulatory reform and liberalisation leading toward competition in the Thai electricity sector, which is still under the monopoly control of state-owned enterprises (SOEs). Following an overview of the current market structure of the Thai electricity sector, the process of liberalisation and deregulation that contributes to the uncompetitive market structure under SOEs’ control is examined. The author asserts that there are problems within the Energy Commission and the Energy Industry Act BE 2550 (2007) that contribute to the continuance of an uncompetitive electricity supply. Possible reforms to the Thai electricity regulation are proposed with the aim of creating market competition and efficiency in the Thai electricity sector.

Abstract In this work, we investigate novel solid–solid phase-change cascade systems based on mixtures of lithium and sodium sulfates. Solid–solid phase-change materials (PCMs) can be coupled with concentrated solar power technologies. They present several advantages over solid–liquid PCMs including lower thermal expansion, lower or no corrosiveness, and no need for encapsulation. In solid–solid PCMs, the energy is stored during crystal structure transitions. Specifically, lithium sulfate undergoes a crystal structure transition (monoclinic to cubic) at 576 °C, which is a suitable temperature for concentrated solar thermal technologies. Due to the high cost of lithium sulfate, we evaluated the potential of mixing lithium with sodium sulfate to create solid–solid cascaded PCM systems to provide higher thermal storage densities. We used differential scanning calorimetry, high-temperature in situ X-ray diffraction and thermogravimetric analysis to evaluate the phase-transition temperature, phase-change enthalpy, specific heat capacity, crystalline phase composition and thermal expansion. The obtained values for heat capacity and enthalpies of phase transitions showed good agreement with available thermodynamic databases. Therefore, further calculations of thermodynamic properties of each mixture in the system were performed for designing cascaded latent thermal energy storage system. From the PCM mixtures studied, NaLiSO4 shows the greatest stability under ambient conditions. A mixture of 59.17% NaLiSO4 and 40.83% Li2SO4 allows an optimum charge of both PCMs for power cycles such as supercritical CO2. Economic assessment revealed that this cascade system has an estimated cost of $50.2 kWhth−1.

Abstract This study examined the impacts of major operating parameters on the performance of a cross flow membrane enthalpy exchanger (MEE) with porous membranes. A lab-scale setup was developed to conduct the experiments based on the test matrix designed with various operating conditions for both heating and cooling operations. The MEE core was made of porous membranes. A mathematical model was developed to predict the transferred heat and moisture fluxes through the membrane. The model implemented a variable moisture diffusivity of the membrane that varied with local air conditions. It was found that the sensible, latent, and total effectiveness of the MEE significantly improved when reducing the airflow rate. In the cooling mode, outdoor air temperature and humidity had a positive influence on the MEE effectiveness, while they showed a negative impact on the heating operations. However, the influences of outdoor conditions on the sensible, latent, and total effectiveness of the MEE were rather insignificant as compared to that of the airflow rate. On the other hand, both airflow rate and outdoor conditions showed significant effects on thermal resistance and total energy recovered for both operating modes. The findings obtained can be used to facilitate optimal design of such devices.

Abstract South Asia is the home of over 1.6 billion people. The countries in the region are aspiring to become fully developed nations by the middle of this century. Rapid industrialization and attainment of sustainable development goals (SDGs) are important requirement to achieve this goal. South Asian nations thus need secured energy and power generation, distribution and supply. Currently the entire South Asian region is energy deficient. Hence achieving energy security and adequate generation of power pose a major challenge. However, regional and sub-regional collaboration in energy and power can enhance energy security if indigenous energy resources are collectively utilized by the member countries. The recently established Indian Energy Exchange (IEX) aims to facilitate in-country and cross-border power and energy trading. Both power producers and buyers can bid live through the IEX platform. This paper reviews some features of IEX and Australian Energy Market Operator (AEMO) in order to understand the operating mechanism of such energy and power trading platforms.