The azeotrope disappeared when the formic acid-water mixtures were treated by membrane distillation. Membrane distillation were used for separation of formic acid-water azeotropic mixtures for the first time.
Ethanol-water near-azeotropic mixture dehydration was investigated by formulated compound starchbased adsorbent(CSA), which consists of corn, sweet potato and foaming agent. The net retention time and separation facto...Ethanol-water near-azeotropic mixture dehydration was investigated by formulated compound starchbased adsorbent(CSA), which consists of corn, sweet potato and foaming agent. The net retention time and separation factor of water over ethanol were measured by inverse gas chromatography(IGC). Results indicated that water has a longer net retention time than ethanol and that low temperature is beneficial to this dehydration process. Orthogonal test was conducted under different vapor feed flow rates, bed temperatures and bed heights, to obtain optimal fixed-bed dehydration condition. Dynamic saturated adsorbance was also studied. It was found that CSA has the same water adsorption capacity(0.15 g/g)as some commercial molecular sieves. Besides, this biosorptive dehydration process was found to be the most energy-efficient compared with other ethanol purification processes.展开更多
A novel,safe,economic and sensitive method of spectrophotometric estimation has been developed using Azeoptropic mixture (water∶methanol:60∶40,v/v) for the quantitative determination of Lornoxicam,a practically wate...A novel,safe,economic and sensitive method of spectrophotometric estimation has been developed using Azeoptropic mixture (water∶methanol:60∶40,v/v) for the quantitative determination of Lornoxicam,a practically water-insoluble drug.Hence,Lornoxicam stock solution was prepared in Azeoptropic mixture.Lornoxicam showed maximum absorbance at 383 nm.Beer's law was obeyed in the concentration range 4-24 μg/mL with regression coefficient of 0.999.The method was validated in terms of linearity (R2=0.999),precision (CV for intra-day and inter-day was 0.28 0.68 and 0.12-0.92,respectively),accuracy (98.03-100.59％ w/w) and specificity.This method is simple,precise,accurate,sensitive and reproducible and can be used for the routine quality control testing of the marketed formulations.展开更多
With the increasing environmental concern on global warming, hydrofluoro-olefin (HFOs), possessing low GWP, has attracted great attention of many researchers recently. In this study, non-azeotropic mixtures composed o...With the increasing environmental concern on global warming, hydrofluoro-olefin (HFOs), possessing low GWP, has attracted great attention of many researchers recently. In this study, non-azeotropic mixtures composed of HFOs (HFO-1234yf, HFO-1234ze(z), HFO-1234ze(e) and HFO-1234zf) are developed to substitute for HFC-134a and CFC-114 in air-conditioning and high-temperature heat pump systems, respectively. The cycle performances were evaluated by an improved theoretical cy-cle evaluation methodology. The results showed that all the mixtures proposed herein were favorable refrigerants with excel-lent thermodynamic cycle performances. M1A presented lower discharge temperature and pressure ratio and higher COPc than that of HFC-134a. The volumetric cooling capacity was similar to HFC-134a. It can be served as a good environmentally friendly alternative to replace HFC-134a. M3H delivered similar discharge temperature as CFC-114 did. And the COPh was 3% higher. It exhibits excellent cycle performance in high-temperature heat pump and is a promising refrigerant to substitute for CFC-114. And the gliding temperature differences enable them to exhibit better coefficient of performance by matching the sink/source temperature in practice. Because the toxicity, flammability and other properties are not investigated in detail, ex-tensive toxicity and flammability testing needs to be conducted before they are used in a particular application.展开更多
The molar heat capacity of the azeotropic mixture composed of water and benzene was measured by an adia-batic calorimeter in the temperature range from 80 to 320 K. The phase transitions took place in the temperature ...The molar heat capacity of the azeotropic mixture composed of water and benzene was measured by an adia-batic calorimeter in the temperature range from 80 to 320 K. The phase transitions took place in the temperature range from 265.409 to 275.165 K and 275.165 to 279.399 K. The phase transition temperatures were determined to be 272.945 and 278.339 K, which were corresponding to the solid-liquid phase transitions of water and benzene, respectively. The thermodynamic functions and the excess thermodynamic functions of the mixture relative to stan-dard temperature 298.15 K were derived from the relationships of the thermodynamic functions and the function of the measured heat capacity with respect to temperature.展开更多
A water-to-water high temperature heat pump was fested experimentally in this work. The inlet water temperature of evaporator was 40 ℃ and the inlet and outlet water temperature of condenser were 70 ℃and 80 ℃ respe...A water-to-water high temperature heat pump was fested experimentally in this work. The inlet water temperature of evaporator was 40 ℃ and the inlet and outlet water temperature of condenser were 70 ℃and 80 ℃ respectively. Almost no conveafioual refrigerant is proper for this high temperature working condition. R22/R141b was taken as heat pump working fluid firstly in this work and heat pump’s pressure performance is improved. Even though the highest cooling water temperature was about 80 ℃,the highest pressure was less than 2 5 MPa and compression ratio was less than 8, which could satisfy R22 compressor’s limits. The performance of system was characterized by refrigerant compositions, compressor RPM and water temperature change. It was found that the coefficient of performance reached its maxim of 2 5 when R22’s molar component was about 75%. If only the water temperature difference in evaporator Δ T E increased, the heating and refrigerating capacity all decreasd. However, the heating and refrigerating capacity all increased with water temperature difference in condenser Δ T C. Frequency of compressor had little influence on heat pump’s COP and working fluid’s (R22/R141b) composition if the compositions and working condition remained unchanged.展开更多
With more and more research being carried out to replace CFC and HCFC,some new green-refrigerant fluids are obtained,but those fluids are only used in some fixed-temperature fields,it limits the used in a bigger range...With more and more research being carried out to replace CFC and HCFC,some new green-refrigerant fluids are obtained,but those fluids are only used in some fixed-temperature fields,it limits the used in a bigger range of variable performance.According to this situation,theory etical and experimentsal’ conclusions are drawn in order to solve this problem in the paper.Non-azeotropic mixtures have temperature-gliding in phase change.CSD equation of state is used for theoretical calculation.Some mixtures that may be used in a bigger range of variable perfomance are found.Experiments are carried out in a refrigerant system.The mixtures S3 is recommended.展开更多
文摘The azeotrope disappeared when the formic acid-water mixtures were treated by membrane distillation. Membrane distillation were used for separation of formic acid-water azeotropic mixtures for the first time.
基金Supported by the Independent Innovation Foundation of Tianjin University(No.2010XY-0013)
文摘Ethanol-water near-azeotropic mixture dehydration was investigated by formulated compound starchbased adsorbent(CSA), which consists of corn, sweet potato and foaming agent. The net retention time and separation factor of water over ethanol were measured by inverse gas chromatography(IGC). Results indicated that water has a longer net retention time than ethanol and that low temperature is beneficial to this dehydration process. Orthogonal test was conducted under different vapor feed flow rates, bed temperatures and bed heights, to obtain optimal fixed-bed dehydration condition. Dynamic saturated adsorbance was also studied. It was found that CSA has the same water adsorption capacity(0.15 g/g)as some commercial molecular sieves. Besides, this biosorptive dehydration process was found to be the most energy-efficient compared with other ethanol purification processes.
文摘A novel,safe,economic and sensitive method of spectrophotometric estimation has been developed using Azeoptropic mixture (water∶methanol:60∶40,v/v) for the quantitative determination of Lornoxicam,a practically water-insoluble drug.Hence,Lornoxicam stock solution was prepared in Azeoptropic mixture.Lornoxicam showed maximum absorbance at 383 nm.Beer's law was obeyed in the concentration range 4-24 μg/mL with regression coefficient of 0.999.The method was validated in terms of linearity (R2=0.999),precision (CV for intra-day and inter-day was 0.28 0.68 and 0.12-0.92,respectively),accuracy (98.03-100.59％ w/w) and specificity.This method is simple,precise,accurate,sensitive and reproducible and can be used for the routine quality control testing of the marketed formulations.
基金supported by the National Natural Science Foundation of China (Grant No. 50976079)Science and Technology Support Key Project of Tianjin (Grant No. 10ZCKFGX01700)
文摘With the increasing environmental concern on global warming, hydrofluoro-olefin (HFOs), possessing low GWP, has attracted great attention of many researchers recently. In this study, non-azeotropic mixtures composed of HFOs (HFO-1234yf, HFO-1234ze(z), HFO-1234ze(e) and HFO-1234zf) are developed to substitute for HFC-134a and CFC-114 in air-conditioning and high-temperature heat pump systems, respectively. The cycle performances were evaluated by an improved theoretical cy-cle evaluation methodology. The results showed that all the mixtures proposed herein were favorable refrigerants with excel-lent thermodynamic cycle performances. M1A presented lower discharge temperature and pressure ratio and higher COPc than that of HFC-134a. The volumetric cooling capacity was similar to HFC-134a. It can be served as a good environmentally friendly alternative to replace HFC-134a. M3H delivered similar discharge temperature as CFC-114 did. And the COPh was 3% higher. It exhibits excellent cycle performance in high-temperature heat pump and is a promising refrigerant to substitute for CFC-114. And the gliding temperature differences enable them to exhibit better coefficient of performance by matching the sink/source temperature in practice. Because the toxicity, flammability and other properties are not investigated in detail, ex-tensive toxicity and flammability testing needs to be conducted before they are used in a particular application.
基金the National Natural Science Foundation of China (No. 20073047) and K. C. Wong Education Foundation, Hong Kong.
文摘The molar heat capacity of the azeotropic mixture composed of water and benzene was measured by an adia-batic calorimeter in the temperature range from 80 to 320 K. The phase transitions took place in the temperature range from 265.409 to 275.165 K and 275.165 to 279.399 K. The phase transition temperatures were determined to be 272.945 and 278.339 K, which were corresponding to the solid-liquid phase transitions of water and benzene, respectively. The thermodynamic functions and the excess thermodynamic functions of the mixture relative to stan-dard temperature 298.15 K were derived from the relationships of the thermodynamic functions and the function of the measured heat capacity with respect to temperature.
基金Project supported by the National Natural Science Foundation of China （No. 20073047） and the Doctor Foundation of Shandong Province （No. 2004B S04021 ）.
文摘混合丙酮，环己烷和甲醇填写了的丙酮，甲醇和 azeotropic 的纯样品的臼齿的热能力被断热的热量计从 78 ～ 320 K 测量。纯样品和混合的稳固固体、稳固液体的阶段转变关于温度基于热能力的曲线被决定。阶段转变发生了在(126.16ication 过程是
基金Project supported by the National Natural Science Foundation of China （No. 20073047） and Doctorial Foundation of Shandong Province （No. 2004BS04021）.
文摘A water-to-water high temperature heat pump was fested experimentally in this work. The inlet water temperature of evaporator was 40 ℃ and the inlet and outlet water temperature of condenser were 70 ℃and 80 ℃ respectively. Almost no conveafioual refrigerant is proper for this high temperature working condition. R22/R141b was taken as heat pump working fluid firstly in this work and heat pump’s pressure performance is improved. Even though the highest cooling water temperature was about 80 ℃,the highest pressure was less than 2 5 MPa and compression ratio was less than 8, which could satisfy R22 compressor’s limits. The performance of system was characterized by refrigerant compositions, compressor RPM and water temperature change. It was found that the coefficient of performance reached its maxim of 2 5 when R22’s molar component was about 75%. If only the water temperature difference in evaporator Δ T E increased, the heating and refrigerating capacity all decreasd. However, the heating and refrigerating capacity all increased with water temperature difference in condenser Δ T C. Frequency of compressor had little influence on heat pump’s COP and working fluid’s (R22/R141b) composition if the compositions and working condition remained unchanged.
文摘With more and more research being carried out to replace CFC and HCFC,some new green-refrigerant fluids are obtained,but those fluids are only used in some fixed-temperature fields,it limits the used in a bigger range of variable performance.According to this situation,theory etical and experimentsal’ conclusions are drawn in order to solve this problem in the paper.Non-azeotropic mixtures have temperature-gliding in phase change.CSD equation of state is used for theoretical calculation.Some mixtures that may be used in a bigger range of variable perfomance are found.Experiments are carried out in a refrigerant system.The mixtures S3 is recommended.
