生活垃圾的物理组成和特性对于垃圾处理设施的有效规划非常重要。以北京市海淀区和东城区典型居住区的生活垃圾作为研究对象,对4个季度生活垃圾的物理组成、含水率和热值进行了分析。结果表明:海淀区和东城区生活垃圾的主要成分均为厨...生活垃圾的物理组成和特性对于垃圾处理设施的有效规划非常重要。以北京市海淀区和东城区典型居住区的生活垃圾作为研究对象,对4个季度生活垃圾的物理组成、含水率和热值进行了分析。结果表明:海淀区和东城区生活垃圾的主要成分均为厨余垃圾、纸类和塑料垃圾,其总和占垃圾总质量的85%以上,其中厨余垃圾的比例最大;通过与早期文献中垃圾物理组成的比较,北京市垃圾物理组成呈现的新变化是厨余垃圾的含量明显下降,纸类和塑料含量均明显上升,灰土含量保持下降。海淀区和东城区4个季度垃圾的平均含水率分别为58.29%和60.62%,平均低位热值分别为5 796.45,5 060.85 k J/kg,故适宜进行焚烧处理。垃圾中塑料和纸类与垃圾热值呈显著相关,含水率与垃圾热值呈负相关。该研究结果可为北京市生活垃圾的管理和设施规划提供参考依据。展开更多
在滇中安宁2006年"3·29"重大森林火灾火烧迹地里没有人为干扰的火烧后光叶石栎灌木林设置样地,并在距离火烧迹地1km处未过火灌木林设置样地做对照,通过外业调查可燃物类型、高度和载量等并在实验室测定活灌木、死可燃物...在滇中安宁2006年"3·29"重大森林火灾火烧迹地里没有人为干扰的火烧后光叶石栎灌木林设置样地,并在距离火烧迹地1km处未过火灌木林设置样地做对照,通过外业调查可燃物类型、高度和载量等并在实验室测定活灌木、死可燃物和CWD的热值、灰分质量分数和点着温度,以单位面积热量为关键指标,对比研究了火烧迹地和未过火灌木林的燃烧性。结果表明,研究样地中火烧迹地光叶石栎灌木林里死可燃物、活可燃物、CWD及总的单位面积热量分别为98 512.51 k J/m2、33 744.36 k J/m2、55 091.52 k J/m2和187 348.39k J/m2,达到较高的值,火烧迹地灌木林总的单位面积热量超过未过火对比灌木林168 944.83 k J/m2;火烧迹地光叶石栎灌木林仍然具有很强的燃烧性,一旦着火,很可能继续释放出大量的热,仍然有可能发展成重大森林火灾,将会对生态环境造成更大的破坏。展开更多
Effective temperature level of stream, namely stream pseudo temperature, is determined by its actual temperature and heat transfer temperature difference contribution value. Heat transfer temperature difference con-tr...Effective temperature level of stream, namely stream pseudo temperature, is determined by its actual temperature and heat transfer temperature difference contribution value. Heat transfer temperature difference con-tribution value of a stream depends on its heat transfer film coefficient, cost per unit heat transfer area, actual tem-perature, and so on. In the determination of the suitable heat transfer temperature difference contribution values of the stream, the total annual cost of multistream heat exchanger network (MSHEN) is regarded as an objective func-tion, and genetic/simulated annealing algorithm (GA/SA) is adopted for optimizing the heat transfer temperature difference contribution values of the stream. The stream pseudo temperatures are subsequently obtained. On the ba-sis of stream pseudo temperature, optimized MSHEN can be attained by the temperature-enthalpy (T-H) diagram method. This approach is characterized with fewer decision variables and higher feasibility of solutions. The calcu-lation efficiency of GA/SA can be remarkably enhanced by this approach and more probability is shown in search-ing the global optimum solution. Hence this approach is presented for solving industrial-sized MSHEN which is difficult to deal by traditional algorithm. Moreover, in the optimization of stream heat transfer temperature differ-ence contribution values, the effects of the stream temperature, the heat transfer film coefficient, and the construc-tion material of heat exchangers are considered, therefore this approach can be used to optimize and design heat exchanger network (HEN) with unequal heat transfer film coefficients and different of construction materials. The performance of the proposed approach has been demonstrated with three examples and the obtained solutions are compared with those available in literatures. The results show that the large-scale MSHEN synthesis problems can be solved to obtain good solutions with the modest computational effort.展开更多
文摘生活垃圾的物理组成和特性对于垃圾处理设施的有效规划非常重要。以北京市海淀区和东城区典型居住区的生活垃圾作为研究对象,对4个季度生活垃圾的物理组成、含水率和热值进行了分析。结果表明:海淀区和东城区生活垃圾的主要成分均为厨余垃圾、纸类和塑料垃圾,其总和占垃圾总质量的85%以上,其中厨余垃圾的比例最大;通过与早期文献中垃圾物理组成的比较,北京市垃圾物理组成呈现的新变化是厨余垃圾的含量明显下降,纸类和塑料含量均明显上升,灰土含量保持下降。海淀区和东城区4个季度垃圾的平均含水率分别为58.29%和60.62%,平均低位热值分别为5 796.45,5 060.85 k J/kg,故适宜进行焚烧处理。垃圾中塑料和纸类与垃圾热值呈显著相关,含水率与垃圾热值呈负相关。该研究结果可为北京市生活垃圾的管理和设施规划提供参考依据。
文摘在滇中安宁2006年"3·29"重大森林火灾火烧迹地里没有人为干扰的火烧后光叶石栎灌木林设置样地,并在距离火烧迹地1km处未过火灌木林设置样地做对照,通过外业调查可燃物类型、高度和载量等并在实验室测定活灌木、死可燃物和CWD的热值、灰分质量分数和点着温度,以单位面积热量为关键指标,对比研究了火烧迹地和未过火灌木林的燃烧性。结果表明,研究样地中火烧迹地光叶石栎灌木林里死可燃物、活可燃物、CWD及总的单位面积热量分别为98 512.51 k J/m2、33 744.36 k J/m2、55 091.52 k J/m2和187 348.39k J/m2,达到较高的值,火烧迹地灌木林总的单位面积热量超过未过火对比灌木林168 944.83 k J/m2;火烧迹地光叶石栎灌木林仍然具有很强的燃烧性,一旦着火,很可能继续释放出大量的热,仍然有可能发展成重大森林火灾,将会对生态环境造成更大的破坏。
基金Supported by the Deutsche Forschungsgemeinschaft (DFG No.RO 294/9).
文摘Effective temperature level of stream, namely stream pseudo temperature, is determined by its actual temperature and heat transfer temperature difference contribution value. Heat transfer temperature difference con-tribution value of a stream depends on its heat transfer film coefficient, cost per unit heat transfer area, actual tem-perature, and so on. In the determination of the suitable heat transfer temperature difference contribution values of the stream, the total annual cost of multistream heat exchanger network (MSHEN) is regarded as an objective func-tion, and genetic/simulated annealing algorithm (GA/SA) is adopted for optimizing the heat transfer temperature difference contribution values of the stream. The stream pseudo temperatures are subsequently obtained. On the ba-sis of stream pseudo temperature, optimized MSHEN can be attained by the temperature-enthalpy (T-H) diagram method. This approach is characterized with fewer decision variables and higher feasibility of solutions. The calcu-lation efficiency of GA/SA can be remarkably enhanced by this approach and more probability is shown in search-ing the global optimum solution. Hence this approach is presented for solving industrial-sized MSHEN which is difficult to deal by traditional algorithm. Moreover, in the optimization of stream heat transfer temperature differ-ence contribution values, the effects of the stream temperature, the heat transfer film coefficient, and the construc-tion material of heat exchangers are considered, therefore this approach can be used to optimize and design heat exchanger network (HEN) with unequal heat transfer film coefficients and different of construction materials. The performance of the proposed approach has been demonstrated with three examples and the obtained solutions are compared with those available in literatures. The results show that the large-scale MSHEN synthesis problems can be solved to obtain good solutions with the modest computational effort.
