The bio-oil produced from the renewable biomass is a sustainable source of aromatic compounds. The aromatic compounds in bio-oil would generally contribute to the coke formation during its further ...processing, which is a bottleneck problem for its further application due to the complex composition of bio-oil. In this study, the distribution and reaction of aromatic compounds during the high-pressure reactive distillation of bio-oil are investigated to achieve the enrichment of aromatic compounds to the distillate fraction. It is found that pressure could help transfer aromatic compounds into the distillate fraction. In addition, the increase of pressure could contribute to the reduction of polymerisation and the production of aromatic monomers due to the hydrothermal environment. Besides the process parameters, methanol could also be used to inhibit the polymerisation of aromatic compounds. Furthermore, the transfer of aromatic compounds could also be intensified using Ca(OH)2 based on the acidity of phenolic compounds.
•High-pressure reactive distillation could enrich aromatics in bio-oil to distillate.•High pressure could help reduce polymerisation and produce aromatic monomers.•High temperature would lead to the severe polymerisation of the aromatic compounds.•Ca(OH)2 could help transfer phenolic compounds to the paste distillate fraction.
It is well known that the mass flux (J) and the membrane thermal efficiency (η) of membrane distillation increase with the feed flow temperature. A comprehensive laminar and turbulent flow model for ...simulating and evaluating the performance of direct contact membrane distillation (DCMD) when operated at inlet feed temperature (Tf,i) from 80°C to 180°C, higher than the customary maximum of ~80°C, was developed and used to explain and assess the performance of such high temperature DCMD, as well as the potential associated problems of the needed higher operating pressure, and provide knowledge useful for their future design and optimization. Some of the key results are that raising Tf,i from 80°C to 180°C, increases J 9.4-fold, and η 2.1-fold, and decreases the specific energy consumption (SEC) 2.9-fold. Raising the flow Reynolds number from 1200 to 7000 increases J 2.6-fold and η by 15%, but SEC increases 2.3-fold. The needed system pressurization does not affect the process performance significantly. The higher operating temperatures also provide more practical opportunities for heat recovery, which could significantly further raise overall system efficiency.
•High temperature membrane distillation•High temperature membrane water desalination•Numerical analysis of high temperature membrane distillation•Membrane properties effects in high temperature membrane distillation•High temperature direct contact membrane distillation
•Discussion of different distillation techniques for ternary azeotropic separation.•Summary of recent process design and control studies from 2015 to 2021.•Provides synchronisation between different ...studies for the same separation mixture.•Identification of gaps within the reviewed publications.•Recommendation of several key areas for future research directions.
The presence of the azeotropes in the binary mixture has resulted in the individual components cannot be effectively separated using the conventional distillation technique. Therefore, several special distillation techniques have been devised that includes conventional extractive distillation (ED), pressure swing distillation (PSD), azeotropic distillation (AD), thermally coupled extractive distillation (TCED), extractive-dividing wall column (EDWC), and side-stream extractive distillation (SSED). These techniques have recently been extended to the separation of ternary azeotropic mixture, with one of the earliest design works published in 2015. At present, there has been a large number of publications available for this topic with the absence of review paper that captures the essential knowledge and insights in these studies. Further, majority of these studies were conducted simultaneously by different groups at different geographical locations, which resulted in the lack of synchronisation between different studies for the same separation mixture. This review paper therefore puts together all these studies conducted in between 2015 and 2021 so that the link between them becomes apparent. These studies were group according to their ternary mixture and the existing gaps were highlighted as recommendation for future works. This review also provides several potential insights as recommendation for future studies on the separation of ternary azeotropic mixture.
Knowledge Distillation: A Survey Gou, Jianping; Yu, Baosheng; Maybank, Stephen J. ...
International journal of computer vision,
06/2021, Volume:
129, Issue:
6
Journal Article
Peer reviewed
Open access
In recent years, deep neural networks have been successful in both industry and academia, especially for computer vision tasks. The great success of deep learning is mainly due to its scalability to ...encode large-scale data and to maneuver billions of model parameters. However, it is a challenge to deploy these cumbersome deep models on devices with limited resources, e.g., mobile phones and embedded devices, not only because of the high computational complexity but also the large storage requirements. To this end, a variety of model compression and acceleration techniques have been developed. As a representative type of model compression and acceleration, knowledge distillation effectively learns a small student model from a large teacher model. It has received rapid increasing attention from the community. This paper provides a comprehensive survey of knowledge distillation from the perspectives of knowledge categories, training schemes, teacher–student architecture, distillation algorithms, performance comparison and applications. Furthermore, challenges in knowledge distillation are briefly reviewed and comments on future research are discussed and forwarded.
•Energy consumption of a pilot AGMD system for seawater desalination was optimised.•Increasing feed temp. & decreasing water circulation reduced energy consumption.•Given a low ΔT, temp. & ...concentration polarisation effects were small.•Feed salinity reduced distillate production rate and increased energy consumption.•The optimised thermal & electrical consumptions were less than all literature values.
This study aimed to optimise an air gap membrane distillation (AGMD) system for seawater desalination with respect to distillate production as well as thermal and electrical energy consumption. Pilot evaluation data shows a notable influence of evaporator inlet temperature and water circulation rate on process performance. An increase in both distillate production rate and energy efficiency could be obtained by increasing the evaporator inlet temperature. On the other hand, there was a trade-off between the distillate production rate and energy efficiency when the water circulation rate varied. Increasing the water circulation rate resulted in an improvement in the distillate production rate, but also an increase in both specific thermal and electrical energy consumption. Given the small driving force used in the pilot AGMD, discernible impact of feed salinity on process performance could be observed, while the effects of temperature and concentration polarisation were small. At the optimum operating conditions identified in this study, a stable AGMD operation for seawater desalination could be achieved with specific thermal and electrical energy consumption of 90 and 0.13kWh/m3, respectively. These values demonstrate the commercial viability of AGMD for small-scale and off-grid seawater desalination where solar thermal or low-grade heat sources are readily available.
Operational excellence for Distillation Units and particularly for Crude Distillation Units is achieved by tight control of product quality which is usually estimated by inferential models. This ...article is focused on a novel approach leading to calculate an appropriate input to the inferential model strictly related to the characteristics of real feed to the column rectifying section where the separation of products occurs. The calculation simplicity based on usually available plant measurements is an additional feature of the proposed approach. This article introduces the definition of a novel curve characterizing hydrocarbon streams: the True Dew Point curve (TDP), whose name recalls the strong relationship with True Boiling Point curve (TBP). Inferential results obtained with the TDP curve have been performed adopting an approximation of the rectifying feed TDP curve with the assumption that any more accurate TDP curve description would give better results. Inferential validation has been carried out comparing the estimations with two different approaches: one based on model input derived from the crude feed TBP curve, assuming that is known and considering these results as benchmark, the other based on a pilot tray temperature (assuming available) as model input for each product. A general database has been built running rigorous simulation models of an atmospheric fractionator, with variations of most operating parameters affecting the distillation ASTM 95% quality chosen as product specification. This article suggests the way to solve problems deriving from high nonlinearity of feed TBP curves, showing the application of TDP methodology to a vacuum fractionator. An application to real laboratory and plant data of atmospheric fractionator is also shown.
Recently, significant performance improvements have been achieved in deep learning-based anomaly detection methods by introducing large neural network architectures and complex anomaly scoring ...functions. However, the computational cost and memory usage required in the inference phase have also increased significantly, thereby limiting their use in real-time applications. In this paper, we propose a score distillation method that adopts the concept of knowledge distillation. An existing high-performance anomaly detection method is used as the teacher. A small neural network is then trained as the student to mimic the scoring function of the teacher. In the inference phase, the anomaly score for a query instance is obtained by a single forward pass through the student network without requiring any complicated computation processes. We demonstrate that the proposed method makes anomaly detection faster and more efficient while maintaining high performance.
Summary
Fractionation is important for the application of milk fat (MF). In this study, the contents of fatty acid (FA) and triglyceride (TAG) of MF and its fractions distilled by short‐path ...molecular distillation (SPMD) were detected. The results showed that a total of 19 FAs and 109 TAG molecular species were detected. Moreover, the short‐chain saturated FA, medium‐chain saturated FA, low‐molecular‐weight TAG, medium‐molecular‐weight TAG, S3 (TAG molecular species with three saturated FAs) and L2S (TAG molecular species with two long‐chain FAs and one short‐chain FA) were easily accumulated in the distillate, and the percentage of these components all increased first and then decreased during the whole distilling process. Compared with the distillate, polyunsaturated FA (PUFA) and high‐molecular‐weight TAG (HMW‐TAG, with the carbon numbers: 41–54 and molecular weight: 704–888) were enriched in the residue, and the increasing ratio of PUFA and HMW‐TAG was 393.75% and 8.58% respectively. Further analysis showed that the 16:0/4:0/16:0, 16:0/4:0/14:0, 16:0/12:0/4:0, etc. were the discrepant TAG molecular species during SPMD. Therefore, these results demonstrated that different fractions of MF could be obtained by adjusting the fractionation temperature, and it also would provide more important theoretical guidance for regulating MF fractionation, enriching the nutritional information of MF fractions.
Using short‐path molecular distillation to fractionated the milk fat and further analyze the fatty acid and triglyceride molecular species of milk fat fractions.
Direct solar steam generation (DSSG) as a green purification technology only driven by solar energy has attracted the attention of researchers. Compared with large-scale water purification ...technologies such as membrane distillation, reverse osmosis and multistage flash distillation, it has convenient, low cost and distributed features. In recent years, water path of evaporator has been gradually optimized and some new strategies has been promoted. In this review, we summarize the development of water path as well as new evaporation strategies including utilizing environmental energy, multi-level utilization of energy efficiency and decreasing evaporation enthalpy. Future research direction and problems to be solved has also been discussed. The current deficiencies and challenges have been pointed to speed the practical application of distributed DSSG purification technology.
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The solar energy produced by Scheffler parabola (10 m
2
) is not fully exploited by the solar distillation system of aromatic and medicinal plants. In this work, the optical losses in the primary and ...secondary reflectors, and the thermal losses at each part of this system (solar still, steam line, condenser) were determined. A thermal energetic and exergetic analysis were also performed for a solar distillation system of rosemary leaves. For average intensity radiation of 849.1W/m
2
and 6 Kg of rosemary leaves during 4 h of distillation, exergy and optical efficiencies of the system achieved up to 26.62% and 50.97%, respectively. The thermal efficiency of the solar still, steam line, and condenser is about 94.80%, 94.30%, and 87.76%, respectively. The essential oil yield per unit of consumed energy and the total efficiency of the solar distillation system, taking into account the heat losses in the solar still, steam line, and condenser, as well as the optical losses in the two reflectors, is 6.18 mL/ kWh and 40.00%, respectively. The efficiency can be as high as 42.42 % if the steam line is insulated. Moreover, the comparison between the solar steam distillation and conventional steam distillation shows that solar distillation is much more efficient since it gives better results and especially it avoids the emission of 12.10 kg of CO
2
during extraction.
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