The relevant standard requirements both in domestic and abroad provide the basis for designing air-conditioning system of railway vehicles present. However, there are great differences in the fresh air volume indicato...The relevant standard requirements both in domestic and abroad provide the basis for designing air-conditioning system of railway vehicles present. However, there are great differences in the fresh air volume indicators among different standards requirements, and the requirements of each vehicle procurement contracts are also different. The design of air-conditioning become difficult above these. In this paper, the fresh air volume of different type railway vehicles is analyzed from health and equipment electricity consumption according to the railway vehicles air-conditioning system standard requirements in domestic and abroad. Some advises for designing air-conditioning system of railway vehicles through the fresh air volume calculation and comparison for domestic air-conditioning system of railway vehicles was provided.展开更多
In this article, a new kind of solar fresh air system is designed in order to realize the improvement of thermal efficiency by the integrated application of the PCMs and heat pipe technology. Under the adequate sunshi...In this article, a new kind of solar fresh air system is designed in order to realize the improvement of thermal efficiency by the integrated application of the PCMs and heat pipe technology. Under the adequate sunshine condition, the fresh air is directly delivered into the indoor environment after being heated by the solar collector. When the sun radiation is reduced, the heated air temperature can not satisfy the need of supply of air temperature.The main heat source is changed to phase change heat storage equipment instead of solar energy. The system adopt heat pipe for a high-efficiency and isothermal heat transfer which recover the shortcomings of PCMs such as： low coefficient of thermal conductivity and poor thermal efficiency. This article establishes the physical model of phase change solar energy fresh air thermal storage system and creates the mathematical model of its unsteady heat transfer to simulate and analyse the operation process by using Fluent software. The results of the study show that, compared to normal fresh air system, the phase change solar energy fresh air thermal storage system has a significant improvement in energy saving and indoor comfort level and will play an important role in the energy sustainable development.展开更多
Fresh air system is the air circulation system of air conditioning, which plays a role in purifying air and circulating indoor air and outdoor air. The fresh air system mainly exhausts the indoor low quality air to th...Fresh air system is the air circulation system of air conditioning, which plays a role in purifying air and circulating indoor air and outdoor air. The fresh air system mainly exhausts the indoor low quality air to the outside through the pipe, so as to make the indoor air fresh. With the continuous development of production technology, people have higher and higher requirements for clean air conditioning technology. Based on this, this paper briefly analyzes the application of clean air conditioning fresh air system in pharmaceutical factory.展开更多
Heavy smog shrouded China＇s central and eastern regions for days this past January, and experts are advising citizens to stay inside. But how much safer is our indoor air？ The U.S. Environmental Protection Agency＇...Heavy smog shrouded China＇s central and eastern regions for days this past January, and experts are advising citizens to stay inside. But how much safer is our indoor air？ The U.S. Environmental Protection Agency＇s research shows that 24 million people in the world die every year as a result of poor indoor air quality, said Song Guangsheng, Secretary General of China＇s Indoor Environment Test Center （CIETC）.展开更多
To achieve required indoor air quality,fresh air supply in buildings should meet relevant standards and regulations.However,the handling of fresh air introduced a cooling load that takes up a large portion of building...To achieve required indoor air quality,fresh air supply in buildings should meet relevant standards and regulations.However,the handling of fresh air introduced a cooling load that takes up a large portion of building energy consumption,especially in tropical and subtropical areas.A proper way should be employed to reduce the cooling load of fresh air.Radiative sky cooling,which is the process that an object cools itself by emitting thermal radiation to outer space without any energy input,is a cost-effective and eco-friendly technology.In this work,a fresh air pre-cooling system using radiative sky cooling is proposed to reduce fresh air cooling load.The system,consisting of filters,a radiative air-cooling system,an air handling unit(AHU),fans,etc.,is installed on the rooftop of the modeled building.Six cities in low-latitude areas are selected and investigated.Results show that with the radiative air-cooling system installed,annual cooling energy consumption of the modeled building can be reduced by around 10%in most cities.For arid areas,e.g.,Abu Dhabi,the system has even better performance with 19.34%annual cooling energy saving.展开更多
Chinese urban residential buildings face serious indoor air quality problems.Air purification systems(e.g.,air purifiers,fresh air systems)that supply fresh air or purify indoor air are widely used in residential buil...Chinese urban residential buildings face serious indoor air quality problems.Air purification systems(e.g.,air purifiers,fresh air systems)that supply fresh air or purify indoor air are widely used in residential buildings to improve indoor air quality.Considering the challenges of energy conservation and emission reduction,it is urgent to guide residents on choosing appropriate air purification systems.The key problem is how to identify the best air purification system with the lowest energy consumption or operating cost.Comparisons of air purification systems have rarely been conducted on the premise that they should deliver air such that the main indoor pollutant concentrations all meet air quality standards.Also ignored in comparisons are the increased filtration resistance caused by dust accumulation on the filter and the cost of filter replacement.In this study,we propose a method to compare residential air purification systems based on energy consumption and total cost,and we provide methods to select air purification systems in China's different climatic regions.We used a standard two-person bedroom as the example,and determined the most suitable(minimum cost or energy consumption)air purification systems for the capital cities of the provinces in Chinese mainland.展开更多
The introduction of fresh air into the indoor space leads to a significant increase in cooling or heating loads.Solid desiccant heat pump fresh air unit which can handle the latent and sensible load of fresh air effic...The introduction of fresh air into the indoor space leads to a significant increase in cooling or heating loads.Solid desiccant heat pump fresh air unit which can handle the latent and sensible load of fresh air efficiently have been proposed recently.To improve the performance of the solid desiccant heat pump fresh air unit in the fresh air handling process,in this paper,the application of composite silica gel in a heat pump fresh air unit was investigated.The comparison between silica gel coating(SGC)and composite silica gel coating(CSGC)shows that the adsorption rate and water uptake capacity of CSGC are more than two times higher than those of SGC.An experimental setup for the solid desiccant heat pump fresh air unit was established.The performance of SGC and CSGC was tested in the setup successively.Results show that under summer conditions,compared with the solid desiccant heat pump fresh air unit using silica gel(SGFU),the average moisture removal and COP of the one using composite silica gel(CSGFU)increased by 15%and 30%,respectively.Under winter conditions,compared with SGFU,the average humidification and COP of CSGFU increased by 42%and 17%.With optimal operation conditions of 3 min switchover time and 40 r/s compressor frequency,the COP of CSGFU under summer conditions can reach 7.6.Results also show that the CSGFU and SGFU have higher COP and dehumidification rate under higher outdoor temperature and humidity ratio.展开更多
Building fresh air supply needs to meet certain regulations and fit people’s ever-growing indoor air quality de-mand.However,fresh air handling requires huge energy consumption that goes against the goal of net-zero ...Building fresh air supply needs to meet certain regulations and fit people’s ever-growing indoor air quality de-mand.However,fresh air handling requires huge energy consumption that goes against the goal of net-zero energy buildings.Thus,in this work,an adaptive fresh air pre-handling system is designed to reduce the cool-ing and heating loads of HVAC system.The sky-facing surface of the system uses electrochromic mechanism to manipulate the optical properties and thus make full use of solar energy(solar heating)and deep space cold source(radiative cooling)by switching between heating and cooling modes.In the cooling mode,the sky-facing surface shows a transmittance of down to zero,while the reflectance is high at 0.89 on average.In the heating mode,the electrochromic glass is highly transparent,allowing the sunlight to reach the solar heat absorber.To obtain the energy-saving potential under different climates,six cities were selected from various climate regions in China.Results show that the adaptive fresh air pre-handling system can be effective in up to 55.4%time of a year.The maximum energy-saving ratios for medium office,warehouse,and single-family house can reach up to 11.52%,26.62%,and 18.29%,respectively.In addition,the system shows multi-climate adaptability and broad application scenarios,making it a potential solution to building energy saving.展开更多
The process of air—sea fresh water exchange is included successfully in the Global— Ocean—Atmosphere Land—System model developed at the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (...The process of air—sea fresh water exchange is included successfully in the Global— Ocean—Atmosphere Land—System model developed at the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG). The results of the coupled integration show that the climate drift has been controlled successfully. Analyses on the responses of ocean circulation to the changes of surface fresh water or salinity forcing show that the ocean spin-up stage under flux condition for salinity is the key to the implementation of air-sea fresh water flux coupling. This study also demonstrates that the Modified—Monthly—Flux—Anomaly coupling scheme (MMFA) brought forward by Yu and Zhang (1998) is suitable not only for daily air—sea heat flux coupling but also for daily fresh water flux coupling. Key words Fresh water flux - Air-sea coupling - Thermohaline circulation This work was co-supported by the National Key Project (Grant No.96-908-02-03), the Excellent National Key Laboratory Research Project (Grant No.49823002) and Chinese Academy of Sciences (CAS) under grant “ Bai Ren Ji Hua? for “Validation of Coupled Climate Models”.展开更多
Fresh air age is an important index to evaluate indoor environment. The conventional method for measuring or calculating fresh air age is only suitable for simple ventilation systems and not for central ven-tilation s...Fresh air age is an important index to evaluate indoor environment. The conventional method for measuring or calculating fresh air age is only suitable for simple ventilation systems and not for central ven-tilation systems. In this paper, an algorithm for calculating fresh air age in central ventilation system is pre-sented, which is based on the analysis of air flow in duct and air mixing. An example is given to illustrate the algorithm. The fresh air age in every ventilated room and duct can be acquired after all rooms and duct are directly calculated in turn without iteration. The algorithm is suitable for different central ventilation sys-tems.展开更多
To explore the method to evaluate air-void parameters of fresh concrete rapidly, the spacing factor and specific surface of freshly mixed concrete of different air contents, different slumps and different mineral admi...To explore the method to evaluate air-void parameters of fresh concrete rapidly, the spacing factor and specific surface of freshly mixed concrete of different air contents, different slumps and different mineral admixtures （fly ash, fly ash-slag, fly ash-slag-silica fume composite） are studied by air-void analyzer （AVA）, and the correlation between the air content measured by AVA and air content determinator is compared. The results show that the spacing factor of the fresh concrete decreases firstly and then increases with the increase of air content, however the specific surface has the opposite rule. When the air content is more than 8%, the spacing factor of fresh concrete increases and the specific surface decreases. For the fresh concrete samples with similar air content, the specific surface increases firstly and then decreases with the increase of slump, but the spacing factor decreases firstly and then increases. Mineral admixalre can reduce the spacing factor of fresh concrete and increase the specific surface to some degree. There is a good correlation between the air content measured by two methods, and the air content measured by AVA is about 70% of the air content measured by the air content determinator.展开更多
In order to reduce the fresh-air handing energy consumption,a fresh-air handing device using earth energy was presented. The major part is a double pipe soil-air heat exchanger. Its performance was tested in summer an...In order to reduce the fresh-air handing energy consumption,a fresh-air handing device using earth energy was presented. The major part is a double pipe soil-air heat exchanger. Its performance was tested in summer and winter. The results show that while the volume of the treated fresh-air is 125 m3/h,in summer,at the outlet of the device,the air temperature is 21.5-24.0 ℃,the air humidity ratio is about 17 g/kg,the greatest temperature drop is about 9 ℃ ,and the largest dehydration quantity is about 6 g/kg. In winter,at the outlet of the device,the air temperature is 15-17 ℃,the air humidity ratio is about 11 g/kg,the largest temperature rise is about 11 ℃,and the largest humidification quantity is about 6 g/kg. Therefore,the application of this new fresh-air handing device can take full advantage of the natural energy,thus effectively reduce the traditional energy consumption for fresh-air handing.展开更多
文摘The relevant standard requirements both in domestic and abroad provide the basis for designing air-conditioning system of railway vehicles present. However, there are great differences in the fresh air volume indicators among different standards requirements, and the requirements of each vehicle procurement contracts are also different. The design of air-conditioning become difficult above these. In this paper, the fresh air volume of different type railway vehicles is analyzed from health and equipment electricity consumption according to the railway vehicles air-conditioning system standard requirements in domestic and abroad. Some advises for designing air-conditioning system of railway vehicles through the fresh air volume calculation and comparison for domestic air-conditioning system of railway vehicles was provided.
文摘In this article, a new kind of solar fresh air system is designed in order to realize the improvement of thermal efficiency by the integrated application of the PCMs and heat pipe technology. Under the adequate sunshine condition, the fresh air is directly delivered into the indoor environment after being heated by the solar collector. When the sun radiation is reduced, the heated air temperature can not satisfy the need of supply of air temperature.The main heat source is changed to phase change heat storage equipment instead of solar energy. The system adopt heat pipe for a high-efficiency and isothermal heat transfer which recover the shortcomings of PCMs such as： low coefficient of thermal conductivity and poor thermal efficiency. This article establishes the physical model of phase change solar energy fresh air thermal storage system and creates the mathematical model of its unsteady heat transfer to simulate and analyse the operation process by using Fluent software. The results of the study show that, compared to normal fresh air system, the phase change solar energy fresh air thermal storage system has a significant improvement in energy saving and indoor comfort level and will play an important role in the energy sustainable development.
文摘Fresh air system is the air circulation system of air conditioning, which plays a role in purifying air and circulating indoor air and outdoor air. The fresh air system mainly exhausts the indoor low quality air to the outside through the pipe, so as to make the indoor air fresh. With the continuous development of production technology, people have higher and higher requirements for clean air conditioning technology. Based on this, this paper briefly analyzes the application of clean air conditioning fresh air system in pharmaceutical factory.
文摘Heavy smog shrouded China＇s central and eastern regions for days this past January, and experts are advising citizens to stay inside. But how much safer is our indoor air？ The U.S. Environmental Protection Agency＇s research shows that 24 million people in the world die every year as a result of poor indoor air quality, said Song Guangsheng, Secretary General of China＇s Indoor Environment Test Center （CIETC）.
基金support from the Natural Science Foundation of Jiangsu Province,China(Grant No.BK20200373).
文摘To achieve required indoor air quality,fresh air supply in buildings should meet relevant standards and regulations.However,the handling of fresh air introduced a cooling load that takes up a large portion of building energy consumption,especially in tropical and subtropical areas.A proper way should be employed to reduce the cooling load of fresh air.Radiative sky cooling,which is the process that an object cools itself by emitting thermal radiation to outer space without any energy input,is a cost-effective and eco-friendly technology.In this work,a fresh air pre-cooling system using radiative sky cooling is proposed to reduce fresh air cooling load.The system,consisting of filters,a radiative air-cooling system,an air handling unit(AHU),fans,etc.,is installed on the rooftop of the modeled building.Six cities in low-latitude areas are selected and investigated.Results show that with the radiative air-cooling system installed,annual cooling energy consumption of the modeled building can be reduced by around 10%in most cities.For arid areas,e.g.,Abu Dhabi,the system has even better performance with 19.34%annual cooling energy saving.
基金supported by the National Natural Science Foundation of China(Grant No.51976106)。
文摘Chinese urban residential buildings face serious indoor air quality problems.Air purification systems(e.g.,air purifiers,fresh air systems)that supply fresh air or purify indoor air are widely used in residential buildings to improve indoor air quality.Considering the challenges of energy conservation and emission reduction,it is urgent to guide residents on choosing appropriate air purification systems.The key problem is how to identify the best air purification system with the lowest energy consumption or operating cost.Comparisons of air purification systems have rarely been conducted on the premise that they should deliver air such that the main indoor pollutant concentrations all meet air quality standards.Also ignored in comparisons are the increased filtration resistance caused by dust accumulation on the filter and the cost of filter replacement.In this study,we propose a method to compare residential air purification systems based on energy consumption and total cost,and we provide methods to select air purification systems in China's different climatic regions.We used a standard two-person bedroom as the example,and determined the most suitable(minimum cost or energy consumption)air purification systems for the capital cities of the provinces in Chinese mainland.
基金the financial support from the National Natural Science Foundation of China(No.51922070)supported by"the Fundamental Research Funds for the Central Universities"。
文摘The introduction of fresh air into the indoor space leads to a significant increase in cooling or heating loads.Solid desiccant heat pump fresh air unit which can handle the latent and sensible load of fresh air efficiently have been proposed recently.To improve the performance of the solid desiccant heat pump fresh air unit in the fresh air handling process,in this paper,the application of composite silica gel in a heat pump fresh air unit was investigated.The comparison between silica gel coating(SGC)and composite silica gel coating(CSGC)shows that the adsorption rate and water uptake capacity of CSGC are more than two times higher than those of SGC.An experimental setup for the solid desiccant heat pump fresh air unit was established.The performance of SGC and CSGC was tested in the setup successively.Results show that under summer conditions,compared with the solid desiccant heat pump fresh air unit using silica gel(SGFU),the average moisture removal and COP of the one using composite silica gel(CSGFU)increased by 15%and 30%,respectively.Under winter conditions,compared with SGFU,the average humidification and COP of CSGFU increased by 42%and 17%.With optimal operation conditions of 3 min switchover time and 40 r/s compressor frequency,the COP of CSGFU under summer conditions can reach 7.6.Results also show that the CSGFU and SGFU have higher COP and dehumidification rate under higher outdoor temperature and humidity ratio.
基金the support from National Natural Sci-ence Foundation of China(52276178)Natural Science Foundation of Jiangsu Province,China(BK20200373).
文摘Building fresh air supply needs to meet certain regulations and fit people’s ever-growing indoor air quality de-mand.However,fresh air handling requires huge energy consumption that goes against the goal of net-zero energy buildings.Thus,in this work,an adaptive fresh air pre-handling system is designed to reduce the cool-ing and heating loads of HVAC system.The sky-facing surface of the system uses electrochromic mechanism to manipulate the optical properties and thus make full use of solar energy(solar heating)and deep space cold source(radiative cooling)by switching between heating and cooling modes.In the cooling mode,the sky-facing surface shows a transmittance of down to zero,while the reflectance is high at 0.89 on average.In the heating mode,the electrochromic glass is highly transparent,allowing the sunlight to reach the solar heat absorber.To obtain the energy-saving potential under different climates,six cities were selected from various climate regions in China.Results show that the adaptive fresh air pre-handling system can be effective in up to 55.4%time of a year.The maximum energy-saving ratios for medium office,warehouse,and single-family house can reach up to 11.52%,26.62%,and 18.29%,respectively.In addition,the system shows multi-climate adaptability and broad application scenarios,making it a potential solution to building energy saving.
文摘The process of air—sea fresh water exchange is included successfully in the Global— Ocean—Atmosphere Land—System model developed at the State Key Laboratory of Atmospheric Sciences and Geophysical Fluid Dynamics (LASG). The results of the coupled integration show that the climate drift has been controlled successfully. Analyses on the responses of ocean circulation to the changes of surface fresh water or salinity forcing show that the ocean spin-up stage under flux condition for salinity is the key to the implementation of air-sea fresh water flux coupling. This study also demonstrates that the Modified—Monthly—Flux—Anomaly coupling scheme (MMFA) brought forward by Yu and Zhang (1998) is suitable not only for daily air—sea heat flux coupling but also for daily fresh water flux coupling. Key words Fresh water flux - Air-sea coupling - Thermohaline circulation This work was co-supported by the National Key Project (Grant No.96-908-02-03), the Excellent National Key Laboratory Research Project (Grant No.49823002) and Chinese Academy of Sciences (CAS) under grant “ Bai Ren Ji Hua? for “Validation of Coupled Climate Models”.
基金supported by the Natural Science Foundation of Beijing(Grant No.8032010).
文摘Fresh air age is an important index to evaluate indoor environment. The conventional method for measuring or calculating fresh air age is only suitable for simple ventilation systems and not for central ven-tilation systems. In this paper, an algorithm for calculating fresh air age in central ventilation system is pre-sented, which is based on the analysis of air flow in duct and air mixing. An example is given to illustrate the algorithm. The fresh air age in every ventilated room and duct can be acquired after all rooms and duct are directly calculated in turn without iteration. The algorithm is suitable for different central ventilation sys-tems.
基金Supported by National Natural Science Foundation of China(No.50908229)and the Technological Research and Development Programs of the Ministry of Railways(No.2008G031-N. 2010G004-E)
文摘To explore the method to evaluate air-void parameters of fresh concrete rapidly, the spacing factor and specific surface of freshly mixed concrete of different air contents, different slumps and different mineral admixtures （fly ash, fly ash-slag, fly ash-slag-silica fume composite） are studied by air-void analyzer （AVA）, and the correlation between the air content measured by AVA and air content determinator is compared. The results show that the spacing factor of the fresh concrete decreases firstly and then increases with the increase of air content, however the specific surface has the opposite rule. When the air content is more than 8%, the spacing factor of fresh concrete increases and the specific surface decreases. For the fresh concrete samples with similar air content, the specific surface increases firstly and then decreases with the increase of slump, but the spacing factor decreases firstly and then increases. Mineral admixalre can reduce the spacing factor of fresh concrete and increase the specific surface to some degree. There is a good correlation between the air content measured by two methods, and the air content measured by AVA is about 70% of the air content measured by the air content determinator.
基金Project(2006BAJ01A02) supported by the Chinese of Science and Technology during the 11th Five-Year Plan Period
文摘In order to reduce the fresh-air handing energy consumption,a fresh-air handing device using earth energy was presented. The major part is a double pipe soil-air heat exchanger. Its performance was tested in summer and winter. The results show that while the volume of the treated fresh-air is 125 m3/h,in summer,at the outlet of the device,the air temperature is 21.5-24.0 ℃,the air humidity ratio is about 17 g/kg,the greatest temperature drop is about 9 ℃ ,and the largest dehydration quantity is about 6 g/kg. In winter,at the outlet of the device,the air temperature is 15-17 ℃,the air humidity ratio is about 11 g/kg,the largest temperature rise is about 11 ℃,and the largest humidification quantity is about 6 g/kg. Therefore,the application of this new fresh-air handing device can take full advantage of the natural energy,thus effectively reduce the traditional energy consumption for fresh-air handing.
