A detailed mechanism analysis of cellulose pyrolysis was carried out according to the previous experimental results. On the basis of the Brodio-Shafizadeh model, a modified two-stage model was proposed to simulate the...A detailed mechanism analysis of cellulose pyrolysis was carried out according to the previous experimental results. On the basis of the Brodio-Shafizadeh model, a modified two-stage model was proposed to simulate the formation and decomposition of active cellulose (AC) and several main organic compounds, such as levoglucosan (LG), hydroxyl-acetaldehyde (HAA), acetol and furfural etc. During pryolysis, the temperature rise of cellulose can be divided into three stages. In the second stage, cellulose undergoes a main decomposition process in which the reaction temperature remains rather low because of the endothermic cracking of glucosidic bond of AC during the formation of LG. The components density of bio-oil, including LG and other competitive compounds, increased rapidly with the increase of temperature during the first stage. However, in the main decomposition process, LG density in bio-oil had an obvious decrease, while the competitive products appeared to increase gradually, which means the ring-opening and reforming reaction of pyranoid ring are superior to LG formation in high temperature.The secondary reaction of volatile components occurs largely in gaseous phase rather than in the solid phase. Short residence time of volatile materials in high temperature region will be advantageous to a high production of LG,which may otherwise decompose quickly under high temperature. An optimum yield of LG could be obtained when radiant source temperature is in the range of 730---920K and gas residence time is less than 1 s. In addition, the reaction temperature has a stronger effect than gas residence time on the formation of HAA, acetol, formaldehyde and furfural etc.展开更多
This summary has introduced the development process of clean technology, and demonstrated the current status and development of cleanroom and relevant environment technology at home and abroad.
Architecture is defined as a symbiosis of function, aesthetics, technology and economics. This paper introduces the concept of development of technology in architecture for a sustainable society. The concept is based ...Architecture is defined as a symbiosis of function, aesthetics, technology and economics. This paper introduces the concept of development of technology in architecture for a sustainable society. The concept is based on a systemic link building-climate-energy. The scientific analysis of this link allows us to define three technical levels of modern architecture. The lowest level is represented by low energy architecture that gives priority to the element of energy. Climate is defined only by physical parameters here. It is characterized by the production of emissions that deplete the Biocapacity of the Earth. Higher level of architecture is represented by green architecture which gives equal priority to both energy and ecology. Climate is defined by physical and chemical parameters here. It is characterized by the tendency of reduction of emissions production and move towards environmentally clean energy, material and water sources. Sustainable architecture represents the target program of development of human settlements in the interaction of society-energy-ecology. It is characterized by the balance of categories nature-man-technology and by minimizing the emissions production to the extent of their coverage by the Earth＇s ecosystems. This paper introduces design strategy for green building. The basic structure of the strategy defines, and internal structure of the strategy emphasizes, principles and concepts of green buildings. In this strategy, the vital role is played by renewable energy sources as a production technology of the capital provided to man by nature.展开更多
基金Supported by the National Natural Science Foundation of China (No. 50176046)Guangdong Government Natural Science Foundation (No. 003045)The experiments in the paper were finished in Zhejiang University.
文摘A detailed mechanism analysis of cellulose pyrolysis was carried out according to the previous experimental results. On the basis of the Brodio-Shafizadeh model, a modified two-stage model was proposed to simulate the formation and decomposition of active cellulose (AC) and several main organic compounds, such as levoglucosan (LG), hydroxyl-acetaldehyde (HAA), acetol and furfural etc. During pryolysis, the temperature rise of cellulose can be divided into three stages. In the second stage, cellulose undergoes a main decomposition process in which the reaction temperature remains rather low because of the endothermic cracking of glucosidic bond of AC during the formation of LG. The components density of bio-oil, including LG and other competitive compounds, increased rapidly with the increase of temperature during the first stage. However, in the main decomposition process, LG density in bio-oil had an obvious decrease, while the competitive products appeared to increase gradually, which means the ring-opening and reforming reaction of pyranoid ring are superior to LG formation in high temperature.The secondary reaction of volatile components occurs largely in gaseous phase rather than in the solid phase. Short residence time of volatile materials in high temperature region will be advantageous to a high production of LG,which may otherwise decompose quickly under high temperature. An optimum yield of LG could be obtained when radiant source temperature is in the range of 730---920K and gas residence time is less than 1 s. In addition, the reaction temperature has a stronger effect than gas residence time on the formation of HAA, acetol, formaldehyde and furfural etc.
文摘This summary has introduced the development process of clean technology, and demonstrated the current status and development of cleanroom and relevant environment technology at home and abroad.
文摘Architecture is defined as a symbiosis of function, aesthetics, technology and economics. This paper introduces the concept of development of technology in architecture for a sustainable society. The concept is based on a systemic link building-climate-energy. The scientific analysis of this link allows us to define three technical levels of modern architecture. The lowest level is represented by low energy architecture that gives priority to the element of energy. Climate is defined only by physical parameters here. It is characterized by the production of emissions that deplete the Biocapacity of the Earth. Higher level of architecture is represented by green architecture which gives equal priority to both energy and ecology. Climate is defined by physical and chemical parameters here. It is characterized by the tendency of reduction of emissions production and move towards environmentally clean energy, material and water sources. Sustainable architecture represents the target program of development of human settlements in the interaction of society-energy-ecology. It is characterized by the balance of categories nature-man-technology and by minimizing the emissions production to the extent of their coverage by the Earth＇s ecosystems. This paper introduces design strategy for green building. The basic structure of the strategy defines, and internal structure of the strategy emphasizes, principles and concepts of green buildings. In this strategy, the vital role is played by renewable energy sources as a production technology of the capital provided to man by nature.
