The use of cooled dialysate temperatures first came about in the early 1980s as a way to curb the incidence of intradialytic hypotension （IDH）. IDH was then, and it remains today, the most common complication affect...The use of cooled dialysate temperatures first came about in the early 1980s as a way to curb the incidence of intradialytic hypotension （IDH）. IDH was then, and it remains today, the most common complication affecting chronic hemodialysis patients. It decreases quality of life on dialysis and is an independent risk factor for mortality. Cooling dialysate was first employed as a technique to incite peripheral vasoconstriction on dialysis and in turn reduce the incidence of intradialytic hypotension. Although it has become a common practice amongst in-center hemodialysis units, cooled dialysate results in up to 70% of patients feeling cold while on dialysis and some even experience shivering. Over the years, various studies have been performed to evaluate the safety and effcacy of cooled dialysate in comparison to a standard, more thermoneutral dialysate temperature of 37℃. Although these studies are limited by small sample size, they are promising in many aspects. They demonstrated that cooled dialysis is safe and equally efficacious as thermoneutral dialysis. Although patients report feeling cold on dialysis, they also report increased energy and an improvement in their overall health following cooled dialysis. They established that cooling dialysate temperatures improves hemodynamic tolerability during and after hemodialysis, even in patients prone to IDH, and does so without adversely affecting dialysis adequacy. Cooled dialysis also reduces the incidence of IDH and has a protective effect over major organs including the heart and brain. Finally, it is an inexpensive measure that decreases economic burden by reducing necessary nursing intervention for issues that arise on hemodialysis such as IDH. Before cooled dialysate becomes standard of care for patients on chronic hemodialysis, larger studies with longer follow-up periods will need to take place to confrm the encouraging outcomes mentioned here.展开更多
This work investigates the transient behaviour of a phase change material based cool thermal energy storage (CTES) system comprised of a cylindrical storage tank filled with encapsulated phase change materials (PCMs) ...This work investigates the transient behaviour of a phase change material based cool thermal energy storage (CTES) system comprised of a cylindrical storage tank filled with encapsulated phase change materials (PCMs) in spherical container integrated with an ethylene glycol chiller plant. A simulation program was developed to evaluate the temperature histories of the heat transfer fluid (HTF) and the phase change material at any axial location during the charging period. The results of the model were validated by comparison with experimental results of temperature profiles of HTF and PCM. The model was also used to investigate the effect of porosity, Stanton number, Stefan number and Peclet number on CTES system performance. The results showed that increase in porosity contributes to a higher rate of energy storage. However, for a given geometry and heat transfer coefficient, the mass of PCM charged in the unit decreases as the increase in porosity. The St number as well as the Ste number is also influential in the performance of the unit. The model is a convenient and more suitable method to determine the heat transfer characteristics of CTES system. The results reported are much useful for designing CTES system.展开更多
The mass of high-speed trains can be reduced using the brake disk prepared with SiC network ceramic frame reinforced 6061 aluminum alloy composite （SiCn/Al）. The thermal and stress analyses of SiCn/Al brake disk dur...The mass of high-speed trains can be reduced using the brake disk prepared with SiC network ceramic frame reinforced 6061 aluminum alloy composite （SiCn/Al）. The thermal and stress analyses of SiCn/Al brake disk during emergency braking at a speed of 300 km/h considering airflow cooling were investigated using finite element （FE） and computational fluid dynamics （CFD） methods. All three modes of heat transfer （conduction, convection and radiation） were analyzed along with the design features of the brake assembly and their interfaces. The results suggested that the higher convection coefficients achieved with airflow cooling will not only reduce the maximum temperature in the braking but also reduce the thermal gradients, since heat will be removed faster from hotter parts of the disk. Airflow cooling should be effective to reduce the risk of hot spot formation and disc thermal distortion. The highest temperature after emergency braking was 461 °C and 359 °C without and with considering airflow cooling, respectively. The equivalent stress could reach 269 MPa and 164 MPa without and with considering airflow cooling, respectively. However, the maximum surface stress may exceed the material yield strength during an emergency braking, which may cause a plastic damage accumulation in a brake disk without cooling. The simulation results are consistent with the experimental results well.展开更多
In order to reduce greenhouse gas emission and urban heat island mitigation, pure and titanium（Ti）-doped Cr2O3 cool pigments were prepared via the thermal decomposition of CrOOH. The result reveals that the pure Cr2...In order to reduce greenhouse gas emission and urban heat island mitigation, pure and titanium（Ti）-doped Cr2O3 cool pigments were prepared via the thermal decomposition of CrOOH. The result reveals that the pure Cr2O3 pigment presents both a high near-infrared reflectance and excellent yellowish-green color. Meanwhile, titanium was doped to improve the NIR reflectance and strengthen the color. The color of the designed pigments was brighter, and most importantly, the NIR reflectance increased from 84.04% to 91.25% with increasing Ti content from 0 to 0.006% （mole fraction）. However, excessive doping of Ti4＋ for Cr3＋ in Cr2O3 （x（Ti）≥0.008%） decreased the NIR reflectance. One possible reason is that the conductivity type of the Cr2？xTixO3＋δ changed from p-type conduction to n-type conduction with increasing Ti content, accompanied by the change of the electrical resistivity and the NIR reflectance. The prepared yellowish-green Cr2O3 pigments have a great potential for extensive applications in construction and military.展开更多
Low-pressure refrigerant gas hydrates have brilliant prospects as a cool storage me-dium for air-conditioning systems. Intensive effects of some specific magnetic fields on the forma-tion process of HCFC-141b refriger...Low-pressure refrigerant gas hydrates have brilliant prospects as a cool storage me-dium for air-conditioning systems. Intensive effects of some specific magnetic fields on the forma-tion process of HCFC-141b refrigerant gas hydrate are depicted experimentally. Under influence of these specific magnetic fields, the orientation and growth region of gas hydrate are altered; induc-tion time of hydrate crystallization can be shortened extremely, and it can be shortened to 40 min from 9 h; hydrate formation mass can be enhanced considerably, and hydration rate can arrive at 100% in some instances. Meanwhile, the relations of induction time and hydration rate changed with magnetic field intensity are depicted, and some elementary regulations are found.展开更多
Evaluating how park characteristics affect the formation of a park cool island(PCI) is the premise of guiding green parks planning in mountain cities.The diurnal variation of PCI intensity was achieved,and correlation...Evaluating how park characteristics affect the formation of a park cool island(PCI) is the premise of guiding green parks planning in mountain cities.The diurnal variation of PCI intensity was achieved,and correlations between PCI intensity and park characteristics such as park area,landscape shape index(LSI),green ratio and altitude were analyzed,using 3 010 temperature and humidity data from measurements in six parks with typical park characteristics in Chongqing,China.The results indicate that:1) the main factor determining PCI intensity is park area,which leads to obvious cool island effect when it exceeds 14 hm2;2) there is a negative correlation between PCI intensity and LSI,showing that the rounder the park shape is,the better the cool island effect could be achieved;3) regression analysis of humidity and PCI intensity proves that photosynthesis midday depression(PMD) is an important factor causing the low PCI intensity at 13:00;4) the multivariable linear regression model proposed here could effectively well predict the daily PCI intensity in mountain cities.展开更多
The temperature of gas flow inside a blast furnace （BF） changes significantly when the blast furnace is under unstable operations, and the temperature and stress distributions of cooling staves （CS） for BF work th...The temperature of gas flow inside a blast furnace （BF） changes significantly when the blast furnace is under unstable operations, and the temperature and stress distributions of cooling staves （CS） for BF work the same pattern. The effect of gas temperature on the temperature, stress, and displacement distributions of the cooling stave were analyzed as the gas temperature inside the blast furnace rose from 1000 to 1600℃ in 900 s. The results show that both the temperature and temperature gradient of the hot side of CS increase when the gas flow temperature inside BF rises. The temperature gradient of the hot side of CS is greater than that of the other area of CS and it can reach 65℃/mm. In the vertical direction of the hot side of CS, closer to the central part of CS, the stress intensity is greater than that of the other area of the hot side of CS, which causes cracks on the hot side of CS in the vertical di- rection. As the gas temperature increases, the stress intensity rate near the fixed pin increases and finally reaches 45 MPa/s. Fatigues near the fixed pin and bolts are caused by great stress intensity rate and the area around the pin can be damaged easily. The edge of CS bends toward the cold side and the central part of CS shifts toward the hot surface.展开更多
文摘The use of cooled dialysate temperatures first came about in the early 1980s as a way to curb the incidence of intradialytic hypotension （IDH）. IDH was then, and it remains today, the most common complication affecting chronic hemodialysis patients. It decreases quality of life on dialysis and is an independent risk factor for mortality. Cooling dialysate was first employed as a technique to incite peripheral vasoconstriction on dialysis and in turn reduce the incidence of intradialytic hypotension. Although it has become a common practice amongst in-center hemodialysis units, cooled dialysate results in up to 70% of patients feeling cold while on dialysis and some even experience shivering. Over the years, various studies have been performed to evaluate the safety and effcacy of cooled dialysate in comparison to a standard, more thermoneutral dialysate temperature of 37℃. Although these studies are limited by small sample size, they are promising in many aspects. They demonstrated that cooled dialysis is safe and equally efficacious as thermoneutral dialysis. Although patients report feeling cold on dialysis, they also report increased energy and an improvement in their overall health following cooled dialysis. They established that cooling dialysate temperatures improves hemodynamic tolerability during and after hemodialysis, even in patients prone to IDH, and does so without adversely affecting dialysis adequacy. Cooled dialysis also reduces the incidence of IDH and has a protective effect over major organs including the heart and brain. Finally, it is an inexpensive measure that decreases economic burden by reducing necessary nursing intervention for issues that arise on hemodialysis such as IDH. Before cooled dialysate becomes standard of care for patients on chronic hemodialysis, larger studies with longer follow-up periods will need to take place to confrm the encouraging outcomes mentioned here.
文摘This work investigates the transient behaviour of a phase change material based cool thermal energy storage (CTES) system comprised of a cylindrical storage tank filled with encapsulated phase change materials (PCMs) in spherical container integrated with an ethylene glycol chiller plant. A simulation program was developed to evaluate the temperature histories of the heat transfer fluid (HTF) and the phase change material at any axial location during the charging period. The results of the model were validated by comparison with experimental results of temperature profiles of HTF and PCM. The model was also used to investigate the effect of porosity, Stanton number, Stefan number and Peclet number on CTES system performance. The results showed that increase in porosity contributes to a higher rate of energy storage. However, for a given geometry and heat transfer coefficient, the mass of PCM charged in the unit decreases as the increase in porosity. The St number as well as the Ste number is also influential in the performance of the unit. The model is a convenient and more suitable method to determine the heat transfer characteristics of CTES system. The results reported are much useful for designing CTES system.
基金Projects (50872018, 50902018) supported by the National Natural Science Foundation of ChinaProject (1099043) supported by the Science and Technology in Guangxi Province, ChinaProject (090302005) supported by the Basic Research Fund for Northeastern University, China
文摘The mass of high-speed trains can be reduced using the brake disk prepared with SiC network ceramic frame reinforced 6061 aluminum alloy composite （SiCn/Al）. The thermal and stress analyses of SiCn/Al brake disk during emergency braking at a speed of 300 km/h considering airflow cooling were investigated using finite element （FE） and computational fluid dynamics （CFD） methods. All three modes of heat transfer （conduction, convection and radiation） were analyzed along with the design features of the brake assembly and their interfaces. The results suggested that the higher convection coefficients achieved with airflow cooling will not only reduce the maximum temperature in the braking but also reduce the thermal gradients, since heat will be removed faster from hotter parts of the disk. Airflow cooling should be effective to reduce the risk of hot spot formation and disc thermal distortion. The highest temperature after emergency braking was 461 °C and 359 °C without and with considering airflow cooling, respectively. The equivalent stress could reach 269 MPa and 164 MPa without and with considering airflow cooling, respectively. However, the maximum surface stress may exceed the material yield strength during an emergency braking, which may cause a plastic damage accumulation in a brake disk without cooling. The simulation results are consistent with the experimental results well.
基金Project(11204304)supported by the National Natural Science Foundation of ChinaProject(2013CB632600)supported by the National Basic Research Program of ChinaProject(2011AA060702)supported by the National High-tech Research and Development Program of China
文摘In order to reduce greenhouse gas emission and urban heat island mitigation, pure and titanium（Ti）-doped Cr2O3 cool pigments were prepared via the thermal decomposition of CrOOH. The result reveals that the pure Cr2O3 pigment presents both a high near-infrared reflectance and excellent yellowish-green color. Meanwhile, titanium was doped to improve the NIR reflectance and strengthen the color. The color of the designed pigments was brighter, and most importantly, the NIR reflectance increased from 84.04% to 91.25% with increasing Ti content from 0 to 0.006% （mole fraction）. However, excessive doping of Ti4＋ for Cr3＋ in Cr2O3 （x（Ti）≥0.008%） decreased the NIR reflectance. One possible reason is that the conductivity type of the Cr2？xTixO3＋δ changed from p-type conduction to n-type conduction with increasing Ti content, accompanied by the change of the electrical resistivity and the NIR reflectance. The prepared yellowish-green Cr2O3 pigments have a great potential for extensive applications in construction and military.
基金This work was supported by the National Natural Science Foundation of China(Grant No.59836230)the Major State Basic Research Program(Grant No.G2000026306)+1 种基金Superintendent Fund of Guangzhou Institute of Energy Conversionthe Chinese Academy of Sciences(Grant No.07-20406).
文摘Low-pressure refrigerant gas hydrates have brilliant prospects as a cool storage me-dium for air-conditioning systems. Intensive effects of some specific magnetic fields on the forma-tion process of HCFC-141b refrigerant gas hydrate are depicted experimentally. Under influence of these specific magnetic fields, the orientation and growth region of gas hydrate are altered; induc-tion time of hydrate crystallization can be shortened extremely, and it can be shortened to 40 min from 9 h; hydrate formation mass can be enhanced considerably, and hydration rate can arrive at 100% in some instances. Meanwhile, the relations of induction time and hydration rate changed with magnetic field intensity are depicted, and some elementary regulations are found.
基金Project(2006BAJ02A02-05) supported by the National Key Technologies R&D Program of China
文摘Evaluating how park characteristics affect the formation of a park cool island(PCI) is the premise of guiding green parks planning in mountain cities.The diurnal variation of PCI intensity was achieved,and correlations between PCI intensity and park characteristics such as park area,landscape shape index(LSI),green ratio and altitude were analyzed,using 3 010 temperature and humidity data from measurements in six parks with typical park characteristics in Chongqing,China.The results indicate that:1) the main factor determining PCI intensity is park area,which leads to obvious cool island effect when it exceeds 14 hm2;2) there is a negative correlation between PCI intensity and LSI,showing that the rounder the park shape is,the better the cool island effect could be achieved;3) regression analysis of humidity and PCI intensity proves that photosynthesis midday depression(PMD) is an important factor causing the low PCI intensity at 13:00;4) the multivariable linear regression model proposed here could effectively well predict the daily PCI intensity in mountain cities.
基金supported by the National Natural Science Foundation of China (No.60672145)
文摘The temperature of gas flow inside a blast furnace （BF） changes significantly when the blast furnace is under unstable operations, and the temperature and stress distributions of cooling staves （CS） for BF work the same pattern. The effect of gas temperature on the temperature, stress, and displacement distributions of the cooling stave were analyzed as the gas temperature inside the blast furnace rose from 1000 to 1600℃ in 900 s. The results show that both the temperature and temperature gradient of the hot side of CS increase when the gas flow temperature inside BF rises. The temperature gradient of the hot side of CS is greater than that of the other area of CS and it can reach 65℃/mm. In the vertical direction of the hot side of CS, closer to the central part of CS, the stress intensity is greater than that of the other area of the hot side of CS, which causes cracks on the hot side of CS in the vertical di- rection. As the gas temperature increases, the stress intensity rate near the fixed pin increases and finally reaches 45 MPa/s. Fatigues near the fixed pin and bolts are caused by great stress intensity rate and the area around the pin can be damaged easily. The edge of CS bends toward the cold side and the central part of CS shifts toward the hot surface.
