Recycle of plastic waste is an indisputable means to alleviate both environment and energy crisis.In this work,effects of heating condition on polyethylene behaviors in nitrogen and air were studied.It was observed th...Recycle of plastic waste is an indisputable means to alleviate both environment and energy crisis.In this work,effects of heating condition on polyethylene behaviors in nitrogen and air were studied.It was observed that polyethylene behavior was a single step in nitrogen,while the multiple steps occurred in air.According to the weight loss and heat flow curves,polyethylene behaviors in air were divided into three regions:low-temperature(<340 ℃),middle-temperature(340 – 380 ℃) and high-temperature(> 380 ℃) regions.Kinetic analysis revealed that the partial oxidization took the dominance in the low-temperature region,which seldom formed CO and CO_(2);the combustion took the dominance in the middle-temperature region,which was positive to the formation of CO and CO_(2);the pyrolysis was initiated and enhanced in the high-temperature region,which inhibited the formation of CO and CO;.According to the kinetic simulation,a synergistic effect between the pyrolysis and combustion was proposed to account for the acceleration of polyethylene conversion.This work may provide useful information about polyethylene behaviors under heating condition,and help to design and optimize plastic waste incineration process.展开更多
The exergy losses and thermodynamic efficiency of MSF plant with brine recirculation are discussed bymeans of temperature difference functions proposed by the auther.In a MSF plant,the irreversible losses are found ma...The exergy losses and thermodynamic efficiency of MSF plant with brine recirculation are discussed bymeans of temperature difference functions proposed by the auther.In a MSF plant,the irreversible losses are found mainly in irreversible heat-transfer and flash evaporationprocesses.However,the basic variables are the temperature drop from stage to stage and the temperaturedifferences between flashed vapor and cooling water.In this paper,the flash temperature difference func-tion,the heat transfer temperature difference function and the total temperature difference function are sug-gested.The proposed temperature difference functions of MSF plant provide a convenient tool to analyse theirreversible behavior and evaluate the exergetic efficiency of this system,because without such improvement thecalculation of the exergetic efficiency of a MSF plant according to the classical formula will be not onlyinconvenient but also insignificant.As a result of present analysis,the reasonable parameters based on theenergy consumption are easily chosen.The above-mentioned principles are confirmed by commercial plants and a pilot plant in Tianjin.展开更多
The relationship among the hydrogen storage properties, cycling characteristics and thermal parameters of the metal hydride air conditioning systems was investigated. Based on a new alloy selection model, three pairs ...The relationship among the hydrogen storage properties, cycling characteristics and thermal parameters of the metal hydride air conditioning systems was investigated. Based on a new alloy selection model, three pairs of hydrogen storage alloys, LaNi_ 4.4 Mn_ 0.26 Al_ 0.34 / La_ 0.6 Nd_ 0.4 Ni_ 4.8 Mn_ 0.2 Cu_ 0.1 ,LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Nd_ 0.4 Ni_ 4.8 Mn_ 0.2 Cu_ 0.1 and LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Y_ 0.4 Ni_ 4.8 Mn_ 0.2 , were selected as the working materials for the metal hydride air conditioning system. Studies on the factors affecting the COP of the system showed that higher COP and available hydrogen content need the proper operating temperature and cycling time,large hydrogen storage capacity, flat plateau and small hysterisis of hydrogen alloys, proper original input hydrogen content and mass ratio of the pair of alloys. It also needs small weight, heat capacity and good heat conductivity of the reaction beds. An experimental metal hydride air-conditioning system was established by using LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Y_ 0.4 Ni_ 4.8 Mn_ 0.2 alloys as the working materials, which showed that under the operating temperature of 180℃/40℃, a low temperature of 13℃ was reached, with COP =0.38 and W_ net =0.09 kW/kg.展开更多
基金the financial support from the National Natural Science Foundation of China (Grant No.21908010)the Jilin Provincial Department of Science and Technology (Grant No.20200201095JC)
文摘Recycle of plastic waste is an indisputable means to alleviate both environment and energy crisis.In this work,effects of heating condition on polyethylene behaviors in nitrogen and air were studied.It was observed that polyethylene behavior was a single step in nitrogen,while the multiple steps occurred in air.According to the weight loss and heat flow curves,polyethylene behaviors in air were divided into three regions:low-temperature(<340 ℃),middle-temperature(340 – 380 ℃) and high-temperature(> 380 ℃) regions.Kinetic analysis revealed that the partial oxidization took the dominance in the low-temperature region,which seldom formed CO and CO_(2);the combustion took the dominance in the middle-temperature region,which was positive to the formation of CO and CO_(2);the pyrolysis was initiated and enhanced in the high-temperature region,which inhibited the formation of CO and CO;.According to the kinetic simulation,a synergistic effect between the pyrolysis and combustion was proposed to account for the acceleration of polyethylene conversion.This work may provide useful information about polyethylene behaviors under heating condition,and help to design and optimize plastic waste incineration process.
文摘The exergy losses and thermodynamic efficiency of MSF plant with brine recirculation are discussed bymeans of temperature difference functions proposed by the auther.In a MSF plant,the irreversible losses are found mainly in irreversible heat-transfer and flash evaporationprocesses.However,the basic variables are the temperature drop from stage to stage and the temperaturedifferences between flashed vapor and cooling water.In this paper,the flash temperature difference func-tion,the heat transfer temperature difference function and the total temperature difference function are sug-gested.The proposed temperature difference functions of MSF plant provide a convenient tool to analyse theirreversible behavior and evaluate the exergetic efficiency of this system,because without such improvement thecalculation of the exergetic efficiency of a MSF plant according to the classical formula will be not onlyinconvenient but also insignificant.As a result of present analysis,the reasonable parameters based on theenergy consumption are easily chosen.The above-mentioned principles are confirmed by commercial plants and a pilot plant in Tianjin.
基金The Natural Science Foundation of China (50266063) .
文摘The relationship among the hydrogen storage properties, cycling characteristics and thermal parameters of the metal hydride air conditioning systems was investigated. Based on a new alloy selection model, three pairs of hydrogen storage alloys, LaNi_ 4.4 Mn_ 0.26 Al_ 0.34 / La_ 0.6 Nd_ 0.4 Ni_ 4.8 Mn_ 0.2 Cu_ 0.1 ,LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Nd_ 0.4 Ni_ 4.8 Mn_ 0.2 Cu_ 0.1 and LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Y_ 0.4 Ni_ 4.8 Mn_ 0.2 , were selected as the working materials for the metal hydride air conditioning system. Studies on the factors affecting the COP of the system showed that higher COP and available hydrogen content need the proper operating temperature and cycling time,large hydrogen storage capacity, flat plateau and small hysterisis of hydrogen alloys, proper original input hydrogen content and mass ratio of the pair of alloys. It also needs small weight, heat capacity and good heat conductivity of the reaction beds. An experimental metal hydride air-conditioning system was established by using LaNi_ 4.61 Mn_ 0.26 Al_ 0.13 /La_ 0.6 Y_ 0.4 Ni_ 4.8 Mn_ 0.2 alloys as the working materials, which showed that under the operating temperature of 180℃/40℃, a low temperature of 13℃ was reached, with COP =0.38 and W_ net =0.09 kW/kg.
