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Effects of process parameters on warpage of rapid heat cycle moulding plastic part 被引量:3
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作者 刘东雷 辛勇 +1 位作者 曹文华 孙玲 《Journal of Central South University》 SCIE EI CAS 2014年第8期3024-3036,共13页
The effects of process parameters in rapid heat cycle moulding (RHCM) on parts warpage were investigated. A vehicle-used blue-tooth front shell (consisting of ABS material) was considered as a part example manufac... The effects of process parameters in rapid heat cycle moulding (RHCM) on parts warpage were investigated. A vehicle-used blue-tooth front shell (consisting of ABS material) was considered as a part example manufactured by RHCM method. The corresponding rapid heat response mould with an innovational conformal heating/cooling channel system and a dynamic mould temperature control system based on the Jll-W-160 type precise temperature controller was proposed. During heating/cooling process, the mould was able to be heated from room temperature to 160 ~C in 6 s and then cooled to 80 ~C in 22 s. The effects of processing conditions in RHCM on part warpage were investigated based on the single factor experimental method and Taguchi theory. Results reveal that the elevated mould temperature reduces unwanted freezing during the injection stage, thus improving mouldability and enhancing part quality, whereas the overheated of mould temperature will lead to defective product. The feasible mould temperature scope in RHCM should be no higher than 140 ~C, and the efficient mould temperature scope should be around the polymer heat distortion temperature. Melt temperature as well as injection pressure effects on warpage can be divided into two stages The lower stage gives a no explicit effect on warpage whereas the higher stage leads to a quasi-linear downtrend. But others affect the warpage as a V-type fluctuation, reaching to the minimum around the heat distortion temperature. Under the same mould temperature condition, the effects of process parameters on warpage decrease according to the following order, packing time, packing pressure, melt temperature, injection pressure and cooling time, respectively. 展开更多
关键词 rapid heat cycle moulding plastic part process parameters WARPAGE
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Dynamic test on waste heat recovery system with organic Rankine cycle 被引量:3
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作者 王志奇 刘力文 +1 位作者 夏小霞 周乃君 《Journal of Central South University》 SCIE EI CAS 2014年第12期4607-4612,共6页
Dynamic performance is important to the controlling and monitoring of the organic Rankine cycle(ORC) system so to avoid the occurrence of unwanted conditions. A small scale waste heat recovery system with organic Rank... Dynamic performance is important to the controlling and monitoring of the organic Rankine cycle(ORC) system so to avoid the occurrence of unwanted conditions. A small scale waste heat recovery system with organic Rankine cycle was constructed and the dynamic behavior was presented. In the dynamic test, the pump was stopped and then started. In addition, there was a step change of the flue gas volume flow rate and the converter frequency of multistage pump, respectively. The results indicate that the working fluid flow rate has the shortest response time, followed by the expander inlet pressure and the expander inlet temperature.The operation frequency of pump is a key parameter for the ORC system. Due to a step change of pump frequency(39.49-35.24 Hz),the expander efficiency and thermal efficiency drop by 16% and 21% within 2 min, respectively. Besides, the saturated mixture can lead to an increase of the expander rotation speed. 展开更多
关键词 organic Rankine cycle waste heat recovery dynamic performance
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Selection of organic Rankine cycle working fluid based on unit-heat-exchange-area net power 被引量:1
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作者 郭美茹 朱启的 +2 位作者 孙志强 周天 周孑民 《Journal of Central South University》 SCIE EI CAS CSCD 2015年第4期1548-1553,共6页
To improve energy conversion efficiency, optimization of the working fluids in organic Rankine cycles(ORCs) was explored in the range of low-temperature heat sources. The concept of unit-heat-exchange-area(UHEA) net p... To improve energy conversion efficiency, optimization of the working fluids in organic Rankine cycles(ORCs) was explored in the range of low-temperature heat sources. The concept of unit-heat-exchange-area(UHEA) net power, embodying the cost/performance ratio of an ORC system, was proposed as a new indicator to judge the suitability of ORC working fluids on a given condition. The heat exchange area was computed by an improved evaporator model without fixing the minimum temperature difference between working fluid and hot fluid, and the flow pattern transition during heat exchange was also taken into account. The maximum UHEA net powers obtained show that dry organic fluids are more suitable for ORCs than wet organic fluids to recover low-temperature heat. The organic fluid 1-butene is recommended if the inlet temperature of hot fluid is 353.15-363.15 K or443.15-453.15 K, heptane is more suitable at 373.15-423.15 K, and R245 ca is a good option at 483.15-503.15 K. 展开更多
关键词 organic Rankine cycle(ORC) working fluid selection net power heat exchange area
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Experimental Evaluation of the Heat Output/Input and Coefficient of Performance Characteristics of a Chemical Heat Pump in the Periodic Operation of CaCl<sub>2</sub>Hydration
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作者 Atsuhiro Ichinose Kazuki Kuwata +2 位作者 Takehiro Esaki Takayuki Matsuda Noriyuki Kobayashi 《Journal of Materials Science and Chemical Engineering》 2020年第11期33-42,共10页
We herein evaluate the use of a chemical heat pump (CHP) for upgrading waste heat. CaCl<sub>2</sub> was used in the system of CHP. We evaluated the heat storage and heat releasing of CHP, and confirmed the... We herein evaluate the use of a chemical heat pump (CHP) for upgrading waste heat. CaCl<sub>2</sub> was used in the system of CHP. We evaluated the heat storage and heat releasing of CHP, and confirmed the practicality from the experimental results. The reactor module employed was an aluminum plate-tube heat exchanger with corrugated fins, and the CaCl<sub>2</sub> powder was in the form of a packed bed. Heat storage operation and heat dissipation operation are performed at the same time and supplied to the heat demand destination. At this time, an environmental heat source can be used during the heat radiation operation, and the heat output can release more heat than the heat input during heat storage. The heat discharging and charging characteristics of the reactor module were evaluated experimentally. The coefficient of performance (COP) was calculated for the heat upgrading cycle, and the heat output in the system was determined. A COP of 1.42 and output of 650 W/L, based on the heat exchanger volume, were obtained using a 600 s change time for the heat pump. 展开更多
关键词 Chemical heat Pump CaCl2/H2O Hydration Reaction heat Pump Cycle Coefficient of Performance
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Influence of Ageing Heat Treatment on the High Cycle Fatigue of an 8090 Al-Li Alloy
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作者 Suhua AI Zhongguang WANG Yun ZHANG and Zhuangqi HU(State Key Laboratory for Fatigue and Fracture of Materials, Institute of Metal Research,Chinese Academy of Sciences, Shenyang 110015, China) 《Journal of Materials Science & Technology》 SCIE EI CAS CSCD 1994年第6期445-450,共6页
Fatigue lives for the smooth and notched specimens of 8090 Al-Li alloy jn the different ageing conditions have been studied. For the smooth samples of 8090 alloy the artificial ageing results in an increase in fatigue... Fatigue lives for the smooth and notched specimens of 8090 Al-Li alloy jn the different ageing conditions have been studied. For the smooth samples of 8090 alloy the artificial ageing results in an increase in fatigue life in comparison with natural ageing. On the contrary, the notched specimens of 8090 alloy in the naturally aged condition show higher fatigue life than in the peak-aged. The exposure to either the peak-aged or naturally aged leads to superior fatigue properties of Al-Li alloy to the traditional high strength aluminum alloys of 7075 and 2024, especially in the latter aged condition. In all ageing conditions, i,e. naturally, under-, peak- and over-aged, the peak-aged 8090 alloy displays the highest fatigue life and the over-aged material has a minimum value at the same stress amplitude. The difference in fatigue life is mainly attributable to the size and distribution of strengthening precipitates as well as the wide of precipitate free zones (PFZ's) along grain boundaries. 展开更多
关键词 AL LI Influence of Ageing heat Treatment on the High Cycle Fatigue of an 8090 Al-Li Alloy
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Performance analysis of a zeotropic mixture(R290/CO_2) for trans-critical power cycle 被引量:3
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作者 潘利生 魏小林 史维秀 《Chinese Journal of Chemical Engineering》 SCIE EI CAS CSCD 2015年第3期572-577,共6页
Low critical temperature limits the application of CO_2 trans-critical power cycle.The binary mixture of R290/CO_2has higher critical temperature.Using mixture fluid may solve the problem that subcritical CO_2 is hard... Low critical temperature limits the application of CO_2 trans-critical power cycle.The binary mixture of R290/CO_2has higher critical temperature.Using mixture fluid may solve the problem that subcritical CO_2 is hardly condensed by conventional cooling water.In this article,theoretical analysis is executed to study the performance of the zeotropic mixture for trans-critical power cycle using low-grade liquid heat source with temperature of200℃.The results indicated that the problem that CO_2 can't be condensed in power cycle by conventional cooling water can be solved by mixing R290 to CO_2.Variation trend of outlet temperature of thermal oil in supercritical heater with heating pressure is determined by the composition of the mixture fluid.Gliding temperature causes the maximum outlet temperature of cooling water with the increase of mass fraction of R290.There are the maximum values for cycle thermal efficiency and net power output with the increase of supercritical heating pressure. 展开更多
关键词 CO2 R290 Zeotropic mixture Low-grade heat energy Trans-critical power cycle
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Energy Saving Model and Calculation Example of Three Cooling Schemes for Data Center in Hot Summer and Cold Winter Area
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作者 Feihu Chen Xinli Zhou Shuguang Liao 《Journal of Power and Energy Engineering》 2021年第12期1-20,共20页
In order to achieve the goal of “carbon peak” in 2030 and “carbon neutralization” in 2060, the task of energy conservation has risen to the national strategic level, and its work is urgent. It focuses on energy sa... In order to achieve the goal of “carbon peak” in 2030 and “carbon neutralization” in 2060, the task of energy conservation has risen to the national strategic level, and its work is urgent. It focuses on energy saving and energy consumption in data center, 5G network and other fields. The gravity heat pipe double cycle air conditioning is a kind of room air conditioning which uses natural cooling source with high efficiency. According to the outdoor meteorological parameters of ten typical cities in China, the calculation model of unit hybrid refrigeration mode is established by using integral method. A simplified algorithm for statistical summation is proposed. Then it compares with the same type of refrigerant pump air conditioner, water-cooled chiller and natural cooling plate. The results show that the annual operation time of gravity heat pipe double cycle air conditioner is 50.8% longer than that of refrigerant pump air conditioner. Then the calculation model is verified by the annual actual operation data of a data center in Changsha. The results show that the double cycle air conditioner with gravity heat pipe can save about 34% energy compared with the chiller. The accuracy of the calculation model is 17.5%, which meets the engineering accuracy requirements. The application of gravity heat pipe double cycle air conditioning in hot summer and cold winter area is a scheme worthy of popularization and application. 展开更多
关键词 Gravity heat Pipe Double Cycle Refrigerant Pump Natural Cooling Inte-gral Method Simplified Algorithm for Statistical Summation Energy Sav-ing Rate
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Exothermic Performance of the Calcined Limestone Determined by Exothermic Temperature under Fluidization during CaCO_(3)/CaO Energy Storage Cycles
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作者 FANG Yi ZHAO Jianli +1 位作者 ZHANG Chunxiao LI Yingjie 《Journal of Thermal Science》 SCIE EI CAS CSCD 2023年第5期1784-1796,共13页
Thermochemical energy storage based on CaO/CaCO_(3)cycles has obtained significant attention as an alternative energy storage solution for concentrated solar power plants.In view of the applicability of fluidized bed ... Thermochemical energy storage based on CaO/CaCO_(3)cycles has obtained significant attention as an alternative energy storage solution for concentrated solar power plants.In view of the applicability of fluidized bed reactors for CaO/CaCO_(3)heat storage,it is imperative to study the factors related to the heat release performance of CaO.This work presents an exothermic experiment on calcined limestone under fluidization,exploring the impact of initial temperature,CO_(2)concentration,particle size,superficial gas velocity,and number of cycles on the exothermic performance of CaO.The result indicates that CaO with high initial temperature leads to higher exothermic temperature,with better exothermic stability under cycles.An optimal initial temperature range of 600℃-650℃exists with an actual CaO conversion rate deviating merely 2%from theoretical conversion.Higher CO_(2)concentration augments the exothermic temperature and rate of CaO,while also improves the effective conversion of CaO.Nevertheless,high CO_(2)concentrations exacerbate the sintering and deactivation of CaO.High superficial gas velocity and small particle size shorten the exothermic time by increasing heat dissipation,but has minimal effect on the exothermic properties.Finally,the exothermic properties of CaO under fluidized and static conditions are studied.The result shows that exothermic temperature and exothermic rate of CaO under fluidization are enhanced,displaying higher heat storage performance than that under static state.This study provides valuable insights for optimizing the exothermic performance of CaO in fluidized bed reactors,contributing to advanced thermochemical energy storage for concentrated solar power plants. 展开更多
关键词 CaO/CaCO_(3)heat storage cycles exothermic temperature FLUIDIZATION exothermic performance
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Study of Cycle Output Improvement by Work-Fluid Including Phase Change Material 被引量:1
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作者 Shin-ichi MORITA Kota TANIMURA +4 位作者 Yasutaka HAYAMIZU Takanobu YAMADA Akihiko HORIBE Naoto HARUKI Toshiaki SETOGUCHI 《Journal of Thermal Science》 SCIE EI CAS CSCD 2016年第6期558-563,共6页
This paper deals with the output improvement of heating and cooling cycle by using the work-fluid including phase change material.The experimental study is carried out by heat exchange between work-fluid and heat tran... This paper deals with the output improvement of heating and cooling cycle by using the work-fluid including phase change material.The experimental study is carried out by heat exchange between work-fluid and heat transfer surface.The work-fluid is flown to a high temperature or a low temperature heat transfer surface from the narrow path.In order to increase the amount of the heat transmission,a trace of Diethylether(boiling point 34.8 ℃),as a phase change material(PCM),is added to the work-fluid.The parameters of the experiment are additive amount of PCM,the rotational speed of the displacer piston and the temperature of heat transfer surface.It is clarified that the increasing of engine cycle output is brought by the PCM addition.The effect of PCM addition is evaluated by output ratio which is defined from the experimental cycle output data.The requirements for acquiring the increasing effect of output by adding PCM are clarified. 展开更多
关键词 heating boiling adding cycle piston clarified narrow additive brought reaches
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