This study reports the component of tar produced from oxidative pyrolysis of cellulose and polypropylene with electron-injected air using a laboratory-scale reactor. This experiment was conducted using a cylindrical fixed bed reactor with a fixed bed. The feedstock tested in this study was cellulose and polypropylene. During experiments, the feedstock was heated by an electric heater to 600, or 700 °C with or without electron- injection into the air. Under all experimental conditions, oxidative pyrolysis occurred immediately after the start of the test. The analysis results of absorbed liquid tar samples show significant differences were observed between with or without electron injection. Electron injection gave a clear impact on tar production during the oxidative pyrolysis of cellulose and polypropylene decomposition.
Density measurements on a binary (0.88 methane + 0.12 propane) mixture were carried out to evaluate the impact of different liquefaction procedures on the composition of condensed gas mixture samples. For these experimental investigations, a low-temperature single-sinker magnetic-suspension densimeter was used. The gaseous mixture was liquefied by condensation and via a special supercritical liquefaction procedure. The densities measured after applying the supercritical procedure serve as reference densities. Based on a comparison of the results of both procedures at otherwise same p,T conditions, the changes in composition can be estimated by differences in density, and these changes are caused by the procedure used for condensation.
It was found that the condensed liquids show distortions in composition of up to 0.94 mole-% that cannot be neglected for the accurate measurement of thermophysical properties. But it was also shown that under appropriate conditions and by applying special condensation procedures, single state points in the homogenous liquid region can be approached with just a minor or no detectable distortion in composition. However, when multiple state points shall be measured over a larger pressure or temperature range, no appropriate and easy method has been found to change the state point of the fluid under survey without significantly changing the composition of the liquefied sample. Only a supercritical liquefaction procedure in combination with a special VLE-cell is suitable for this application.
Natural gas pipeline networks gradually show a trend of system complexity. The complicated topological structure of natural gas pipeline network is likely to cause inherent structural defects, which has critical impacts on the safe operation of natural gas pipeline network. In order to understand the complexity of natural gas pipeline network and its behaviors when facing structural changes, this paper studies the complexity of natural gas pipeline network based on complex network theory. The complexity analysis results in this paper show that when the gate station is used as the expression scale, natural gas pipeline network has the small-world characteristics. This paper also creatively studied the structural characteristics of natural gas pipeline network, and defined the expression of natural gas pipeline network structure. The research results show that the 3-3 structure and the 3-4 structure are the main structures of natural gas pipeline network, which is of great significance to the future research of natural gas pipeline network.
This paper proposes a two-stage robust optimal scheduling method for the integrated community energy system (ICES) with flexible heating loads of buildings. At the first stage, consumers in buildings optimize their heating loads to minimize their heating costs. The thermal dynamics of buildings with controllable indoor radiators are modeled using the Resistor-Capacitor thermal network. At the second stage, the ICES operator seeks to maximize its profit by optimizing the schedules of energy generation and supply. Moreover, a robust optimization is used at the second stage to cope with the energy prices uncertainties from the energy markets. Numerical studies show that the proposed optimal scheduling method can reduce the heating costs of consumers in buildings while ensuring the ICES’s profit under energy prices uncertainties.
In order to reduce the energy consumption of cement clinker firing process and achieve green energy-saving production, a high-precision, strong and stable process model is urgently needed. However, in the process of modeling cement clinker firing process with data-driven modeling method, in addition to the objective difficulties of multivariable, nonlinear, large delay and strong coupling of the firing process itself, and the data collected from cement production sites can also make modeling more difficult due to its complexity, repeatability, and incompleteness., in order to make more effective use of the information contained in the data and obtain the cement clinker firing process model with higher accuracy and stability. This paper proposes a series of data preprocessing steps for the raw data, which can remove the redundant information in the data and make the modeling process more efficient and accurate. Data preprocessing includes time domain unification, abnormal data elimination, data filtering and principal component analysis.
Green ammonia has received much interest in Australia as a key carrier for international exports. Here we present a model to evaluate the impact of temporal operational flexibility of electrolysers and the Haber-Bosch process on the optimal design of the ammonia production system. We show green ammonia can be cost-competitive if the system is well-optimised to cope with renewables variability.
Building energy management is crucial to meet carbon neutrality targets between 2050 and 2060. Yet, building energy management standards and codes are struggling to be updated quickly due to misunderstanding from stakeholders outside the standard and code revision committees. This paper explores opportunities to clarify the misunderstanding through digitization of data collected from statuary submissions for these standards and codes of various buildings. 239 building energy audit cases in Hong Kong between 2019 and 2021 are digitized with a smart energy audit tool and analyzed. The results show not only opportunities to counterargue misunderstanding from the stakeholders on the impossibility to follow proposed standards, they also show new opportunities of new building energy management techniques to further reduce building energy use and to meet carbon neutrality targets.
The solar power tower (SPT) is one of the most common applications of concentrating solar power technology. The tower receiver is the core component in a SPT system, responsible for solar absorption and solar conversion by depositing one single solar selective-absorbing coating (SSC), which usually has a fixed spectral selectivity characteristic. Owing to highly non-uniform optical distribution on the receiver surface, the tower receiver is riddled with complex physics coupled with optical, thermal and mechanical problems. The SSC exerts crucial roles in the activity in the physical process of optical-thermal conversion. However, given the complex physics on the surface of the tower receiver, the common SSCs used in the tower receiver are far from the optimal design of SSC in terms of spectral selectivity, which leads to the less efficient solar-thermal conversion in the tower receiver. In this paper, a comprehensive spectral heat transfer model of the tower receiver was first established and verified. The calculation accuracy of the proposed model was significantly improved by 10% compared with the conventional model. In this context, the mechanism of optimal spectral selectivity of SSC in response to the different concentration ratios and service temperatures was fully revealed. Dunhuang 10 MW SPT was selected as a study case, and the tower receiver covered with a variety of SSCs with optimal spectral selectivity was analyzed. The potential performance in the solar-thermal conversion of the tower receiver was analyzed as well. The results showed that the optimal spectral selectivity of SSC varied dramatically with the solar irradiance density and receiver surface’s temperature, revealing the mismatches problem of the current SSC on the next-generation SPT system. The tower receiver with optimal SSCs exhibited the largest improvement potential in receiver efficiency and pointed out the development direction for the next-generation tower receiver.
To examine the development of smart city technologies to support energy policy development for carbon neutrality, a preliminary literature review was performed to categorize literature of smart city technologies based on their relevance to various stages of policy cycles of energy policies. The study was conducted by Sub-keyword Synonym Searching with keywords of smart city technologies between 2016 and 2020 and stages of policy cycles. The results showed that hot topics in smart city technologies such as circular economy, big data, circular economy, energy water nexus and microgrids are well investigated, but there was a lack of smart city technologies to support the agenda-setting process of energy policy development and a lack of development in smart city technologies directly related to policies such as smart building and smart city framework.
Methane hydrate (MH) is considered as one of the most promising clean energy. In this study, the effects of overlying water on the formation and dissociation of MHs in sediments were analyzed. The results indicate that the overlying water can provide the sufficient water source and the driving force for hydrate formation. The time required to synthesize hydrate sample with high saturation (44.1%) is effectively shortened. Additionally, the overlying water contributes to the heat and mass transfer, thereby promoting the hydrate dissociation and the gas-water production during depressurization. The findings of this study could pave the way for the utilization of overlying water to enhance the gas production efficiency for marine hydrate exploitation.