Electroosmosis has been shown to be an effective means of different applications in various fields such as Micro-Electro-Mechanical systems (MEMS) and biomimetics applications. This paper aims to prove the concept t...Electroosmosis has been shown to be an effective means of different applications in various fields such as Micro-Electro-Mechanical systems (MEMS) and biomimetics applications. This paper aims to prove the concept that the electroosmosis phenomena can also be cooperated into larger scale applications in the building service industry like dehumidification or damping proof. The electroosmotic flow inside a porous medium is validated experimentally to further understand the dehumidification mechanism of combined techniques. An experimental test validates that the condensation from the porous medium can be obtained by electroosmotic force generated by external electric field, especially for specific desiccant powders like zeolite and diatomaceous earth. With a range of volts from 5 V to 20 V applying between the testing plates, the maximum flow rate through the cross section in the testing plate achieved during the peak period is 1.35 laL'min 1. These promising phenomena can act as an alternative way for energy choice in dehumidification industrial field. Further researches on new regeneration methods for solid desiccant dehumidification are required to make the system simple, energy-saving and suitable for small air conditioning units.展开更多
A vertical tubular desalination unit with shell and tube structure was built to perform humidification and dehumidification simultaneously on the tube and shell side of the column, respectively. The effects of several...A vertical tubular desalination unit with shell and tube structure was built to perform humidification and dehumidification simultaneously on the tube and shell side of the column, respectively. The effects of several operating conditions on the productivity and thermal efficiency of the column were investigated. The results show that both the productivity and thermal efficiency of the column enhance with the elevation of the inlet water temperature. The flow rates of water and carrier gas both have optimal operating ranges, which are 10-30 kg·h^-1 and 4-7kg·h^-1 for the present column, respectively. Meanwhile, the increase of external steam flow rate will promote the productivity of the column but reduce its thermal efficiency.展开更多
Solar humidification-dehumidification desalination technology has been reviewed in detail in this paper. This review would also throw light on the scope for further research and recommendations in active distillation ...Solar humidification-dehumidification desalination technology has been reviewed in detail in this paper. This review would also throw light on the scope for further research and recommendations in active distillation system by humidification and dehumidification (HDH). Also in this article, a review has been done on different types of (HDH) systems. Thermal modeling was done for various types of humidification and dehumidification(HDH) distillation system. From the present review, it is found that the humidification-dehumidification desalination process HDH will be a suitable choice for fresh water production when the demand is decentralized. HDH is a low temperature process where total required thermal energy can be obtained from solar energy. Capacity of HDH units is between that produced by conventional methods and solar stills. Moreover, HDH is distinguished by simple operation and maintenance. Also from the present condensed review, it was observed that an increase in evaporator and condenser surface areas significantly improves system productivity. But prior to implementing any techniques in design improvement, it is necessary to optimize the MEH unit by optimizing its component size to understand the effect of feed water and air flow rates. Although a fair amount of simulation studies have been conducted in the past, further design simulation is required to fully understand the complicated effects of air and water flow rates, the optimum size of individual components or modules of the unit and to generate a comprehensive model for the system.展开更多
The modelling and experimental investigation of a thermally coupled humidification-dehumidification desalination process using a carbon-filled-polypropylene shell-tube column are presented.A heat/mass transfer model i...The modelling and experimental investigation of a thermally coupled humidification-dehumidification desalination process using a carbon-filled-polypropylene shell-tube column are presented.A heat/mass transfer model is established to study the correlation among productivity,thermal efficiency,physicochemical parameters (gas/liquid phase temperature,heat/mass transfer coefficient,Reynolds number etc.),and operating conditions(the temperature of feed water,the flow rates of external steam,feed water,and carrier air);at the same time,the effects of operating conditions on the productivity and thermal eficiency of the column are investigated both theoretically and experimentally,which indicate that the optimum flow rates of external steam,feed water,and carrier gas are 0.18,60,and 10kg.h- 1,respectively,and the higher the feed water temperature(≤95℃)is,the greater the productivity and the thermal efficiency will be.Furthermore,performance comparison with the previous study shows that the condensate productivity of this carbon-filled-plastic column is not lower than that of the copper column,which demonstrates the practicability and feasibility of applying such a plastic column to the humidification-dehumidification desalination process.展开更多
The aim of this research was to study and design a solid desiccant dehumidification system suitable for tropical climate to reduce the latent load of air-conditioning system and improve the thermal comfort. Different ...The aim of this research was to study and design a solid desiccant dehumidification system suitable for tropical climate to reduce the latent load of air-conditioning system and improve the thermal comfort. Different dehumidifiers such as desiccant column and desiccant wheel were investigated. The ANSYS and TRASYS software were used to predict the results of dehumidifiers and the desiccant cooling systems, respectively. The desiccant bed contained approximately 15 kg of silica-gel, with 3 mm average diameter. Results indicated that the pressure drop and the adsorption rate of desiccant column are usually higher than those of the desiccant wheel. The feasible and practical adsorption rate of desiccant wheel was 0.102 kgw/h at air flow rate 1.0 kg/min, regenerated air temperature of 55?C and at a wheel speed of 2.5 rpm. The humidity ratio of conditioning space and cooling load of split-type air conditioner was decreased to 0.002 kgw/kgda (14%) and 0.71 kWth (19.26%), respectively. Consequently, the thermal comfort was improved from 0.5 PMV (10.12% PPD) to 0.3 PMV (7.04% PPD).展开更多
This review compares the different types of membrane processes for air dehumidification.Three main categories of membrane-based dehumidification are identified–membrane contactors using porous membranes with concentr...This review compares the different types of membrane processes for air dehumidification.Three main categories of membrane-based dehumidification are identified–membrane contactors using porous membranes with concentrated liquid desiccants,separative membranes using dense membrane morphology with a pressure gradient to drive the separation of moisture from air,and adsorptive membranes using nanofibrous membranes which adsorb and capture moisture to realise dehumidification.Drawing upon the importance of dehumidification and humidity control for urban sustainability and energy efficacy,this review critically analyses and recognizes the three unique categories of membrane-based air dehumidification technologies.Essentially,the discussion is broken into three sections-one for each category-discriminating in terms of the driving force,membrane structure and properties,and its performance indicators.Readers will notice that despite having the same objective to dehumidify air,the polymers used amongst each category differs to suit the operating requirements and optimize dehumidification performance.At the end of each section,a performance table or summary of dehumidifying membranes in its class is provided.The final section concludes with a comparative review of the three categories on membrane-based air dehumidification technologies and draw inspiration from parallel research to rationalise the potential and innovative use of promising materials in membrane fabrication for air dehumidification.展开更多
Temperature and humidity independent control(THIC)air-conditioning system is a promising technology.In this work,a novel temperature and humidity independent control(THIC)system is proposed,namely VMD-ACERS,which inte...Temperature and humidity independent control(THIC)air-conditioning system is a promising technology.In this work,a novel temperature and humidity independent control(THIC)system is proposed,namely VMD-ACERS,which integrates vacuum membrane-based dehumidification and air carrying energy radiant air-conditioning system.This work establishes a novel coefficient of performance(COP)model of VMD-ACERS.The main parameters affecting the COP of conventional fan coil unit cooling system(FCUCS)and VMD-ACERS are investigated.The performance of FCUCS and VMD-ACERS are compared,and the energy-saving potential of VMD-ACERS is proved.Results indicate that,for FCUCS,the importance ranking of parameters is basically stable.However,for VMD-ACERS,the importance ranking will be affected by FCU and refrigerant.The most important parameters of VMD-ACERS are condensation temperature and permeate side pressure.On the contrary,superheating,subcooling are relatively less important parameters.For VMD-ACERS,it is not necessary to pursue the membrane with very high selectivity,because the selectivity of membrane would also be a less important parameter when it reaches 500.The COP of VMD-ACERS is higher than that of FCUCS when the permeate side pressure is higher than 8 k Pa.The VMD-ACERS solves two technical problems about power-saving and thermal comfort of conventional THIC,and can extend the application of THIC air-conditioning system.展开更多
Most of the desalination technologies consume a huge quantity of energy resulting from petroleum products in the form of heat or electrical energy. Solar desalination is a promisingly sustainable freshwater production...Most of the desalination technologies consume a huge quantity of energy resulting from petroleum products in the form of heat or electrical energy. Solar desalination is a promisingly sustainable freshwater production technology. Solar desalination humidification dehumidification process showed the best approach as it is of the highest overall energy efficiency. In this review paper, a detailed study of the previous work is performed on solar humidification dehumidification desalination techniques experimentally and theoretically. Also in this review, different types of HDH systems were mentioned. The review showed that the humidification dehumidification desalination systems are suitable for decentralized demand. On the other hand, capacity of HDH units is not as large as conventional methods or small as solar stills. Finally, this study threw light on the scope of the parameters which have a considerable influence on increasing the freshwater output of the HDH systems as feed water flow rate, air flow rate, and design of the evaporator, condenser, and packing material. A brief economical study and a comparison of the costs per liter are performed for various humidification dehumidification desalination systems presented in this study.展开更多
The necessity of the main cable anticorrosion for suspension bridge is described, and operating principles and composition of main cable dehumidification system are analyzed. An idea using the waste heat of high tempe...The necessity of the main cable anticorrosion for suspension bridge is described, and operating principles and composition of main cable dehumidification system are analyzed. An idea using the waste heat of high temperature outlet air of dehumidification system to heat up regeneration air of rotary-type dehumidifier is put forward in this paper. The concrete scheme is to install a heat exchanger on air-out pipeline of roots blower and air-in pipeline of regeneration electric heater of rotary dehumidifier. Air preheated by the heat exchanger enters regeneration electric heater of rotary-type dehumidifier. Energy conservation of main cable dehumidification system for the Yangtze River highway bridge is calculated, and the results show that energy conservation rate can reach 44 %.展开更多
The polypropylene tubes with surface modification were installed in a baffled shell-tube column to conduct the thermally coupled humidification and dehumidification desalination process. The effects of several operati...The polypropylene tubes with surface modification were installed in a baffled shell-tube column to conduct the thermally coupled humidification and dehumidification desalination process. The effects of several operating parameters (feed water temperature, water flow rate, carrier air flow rate, and external steam flow rate) on the productivity and thermal efficiency of this column were investigated experimentally. The results show that the feed water temperature has a positive effect on the productivity and thermal efficiency, while the flow rates of external steam, feed water,and carrier air should be optimized within the ranges of 0.006—0.020 kg·m-2·s-1, 0.005—0.015 kg·m-1·s-1, and 0.7—1.3 kg·m-2·s-1, respectively; the flow rates of feed water and carrier air are greatly controlled by the wetting state of the tubes. In comparison with the previous desalination column installing the coppery tubes, the present column can reach nearly the same production capacity of distilled water, which demonstrates the feasibility of applying such a plastic column to the humidification and dehumidification desalination process.展开更多
To calculate the flow resistance of a main cable dehumidification system,this study considers the air flow in the main cable as the flow in a porous medium,and adopts the Hagen–Poiseuille equation by using average hy...To calculate the flow resistance of a main cable dehumidification system,this study considers the air flow in the main cable as the flow in a porous medium,and adopts the Hagen–Poiseuille equation by using average hydraulic radius and capillary bundle models.A mathematical derivation is combined with an experimental study to obtain a semi-empirical flow resistance formula.Additionally,Fluent software is used to simulate the flow resistance across the main cable relative to the experimental values.Based on the actual measured results for a Yangtze River bridge,this study verifies the semi-empirical formula,and indicates that it can be applied in actual engineering.展开更多
In order to improve the thermal environment of high-temperature heading face,moisture content of supply air is reduced by dehumidification, and the relative humidity ofenvironment air of the heading face is also decre...In order to improve the thermal environment of high-temperature heading face,moisture content of supply air is reduced by dehumidification, and the relative humidity ofenvironment air of the heading face is also decreased.First, according to the coefficient ofperformance of dehumidifier, the capacity of dehumidification was calculated.Second, inthe engineering example of the heading face, quantitative changes of WBGT (Wet BulbGlobe Temperature) were compared between with dehumidification and without dehumidification.Based on WBGT standards, the thermal comfort of high-temperature environmentof heading face was evaluated between with dehumidification and without handling.Reducingthe relative humidity of airflow through dehumidification, the thermal comfort of ahigh-temperature environment of heading face can improve greatly.Even if dry bulb temperatureof airflow is not decreased, the thermal comfort of heading face environment isalso improved to some extent.展开更多
Atmospheric water absorption by plants has been explored for more than two centuries, and the aerial parts of plants, particularly the leaves of certain species, have been demonstrated to have an ability to absorb and...Atmospheric water absorption by plants has been explored for more than two centuries, and the aerial parts of plants, particularly the leaves of certain species, have been demonstrated to have an ability to absorb and utilize saturated atmospheric water such as fog, dew and condensed water. So far, however, there have been few studies on the aerial parts of desert plants in their absorption of unsaturated water from the atmosphere. This study presents an ultrasonic humidification fluorescent tracing method of detecting unsaturated atmospheric water absorption by the aerial parts of desert plants. We constructed an organic glass room based on the sizes of field plants. Then, the aboveground parts of the plants were humidified in the sealed glasshouse using an ultrasonic humidifier containing fluorescent reagents. The humidity and wetting time were controlled by turning on or off the humidifier according to the reading of a thermo-hygrometer suspended in the glasshouse. Fluorescence microscopy was employed to observe these plant samples. This method can generate unsaturated atmospheric water vapor and incorporate other fluorescent reagents or water-soluble chemical reagents for gasified humidification. In addition, it can identify plant parts that absorb unsaturated atmospheric water from the air, detect water absorption sites on the surface of leaves or tender stems, and determine the ability of tissues or microstructure of aerial parts to absorb water. This method provides a direct visual evidence for the inspection of leaf or tender stem microstructure in response to unsaturated atmospheric water absorption. Moreover, this method shows that aqueous pores in the cuticles of leaves or tender stems of desert plants are large enough to allow the passage of ionic fluorescent brightener with a molecular weight of up to 917 g/mol. Thus, this paper provides an important approach that explores the mechanism by which desert plants utilize unsaturated atmospheric water.展开更多
Indoor air quality has a direct impact on human health. Indoor air quality has aroused great concern. This experimental study compares the effects of different water humidification on the indoor particulate pollution ...Indoor air quality has a direct impact on human health. Indoor air quality has aroused great concern. This experimental study compares the effects of different water humidification on the indoor particulate pollution characteristics, and analyzes the mass concentration and the particulate number concentration distribution of different sizes of particulates with time under each condition of the purified water humidification, the tap water humidification and the cold boiled water humidification in the office. The results show that under the three kinds of wetting conditions, the concentration of the fine particulates is higher. More minerals are contained in the tap water and the cold boiled water, so the two kinds of humidification have more significant impact on indoor particulate matter. But the purified water humidification has nearly no significant effect on it. The calcium and magnesium ionic compounds are partly removed after the water boiled, so the cold boiled water humidification has less impact on the indoor particulate matter than the tap water humidification. The mass concentration and particulate number concentration of the particle may also be affected due to the frequency of ultrasonic vibration.展开更多
Humidification is an important step in humid air turbine system. The calculation on humidification is carried out at 423.15—573.15K, 5—15MPa. The results suggest that to produce high-enthalpy moist air, high water t...Humidification is an important step in humid air turbine system. The calculation on humidification is carried out at 423.15—573.15K, 5—15MPa. The results suggest that to produce high-enthalpy moist air, high water temperature and large water flow are needed. The water temperature is the most sensitive parameter to the humidification tower. And it is better for the humidification tower to work at temperature higher than 523 K when the system pressure is higher than 5 MPa. The comparison between the model used in this paper and ideal model shows that the ideal model can be used in simulation to simply the calculation when the temperature is lower than 473 K and pressure is lower than 5 MPa.展开更多
A theoretical model of a humidifier of proton exchange membrane (PEM) fuel cell systems is developed and analyzed first in this paper. The model shows that there exists a strong nonlinearity in the system. Then, the...A theoretical model of a humidifier of proton exchange membrane (PEM) fuel cell systems is developed and analyzed first in this paper. The model shows that there exists a strong nonlinearity in the system. Then, the system is identified using a wavelet networks method. To avoid the curse-of-dimensionality problem, a class of wavelet networks proposed by Billings is employed. The experimental data acquired from the test bench are used for identification. The one-step-ahead predictions and the five-step-ahead predictions are compared with the real measurements, respectively. It shows that the identified model can effectively describe the real system.展开更多
Objective: To investigate the continuous humidification tube insertion depth of endotracheal intubation and the flow rate of the wetting effect. Methods: From October 2008 to May 2010, among 132 patients of oral and m...Objective: To investigate the continuous humidification tube insertion depth of endotracheal intubation and the flow rate of the wetting effect. Methods: From October 2008 to May 2010, among 132 patients of oral and maxillofacial surgery with tracheal intubation, continuous infusion can be adjusted to the wet method;according to the wet pipe, insertion depth of the flow rate is divided into four groups, by four different depths and velocities of the wetting effect, to be analyzed. Results: B group was significantly lower than other groups satisfied with indicators of four significantly different effects of humidification. Conclusion: When continuous humidification tube insertion depth of endotracheal intubation is 10 - 12 cm, and flow rate is 15 - 20 ml/h, the wetting effect will achieve greater satisfaction.展开更多
文摘Electroosmosis has been shown to be an effective means of different applications in various fields such as Micro-Electro-Mechanical systems (MEMS) and biomimetics applications. This paper aims to prove the concept that the electroosmosis phenomena can also be cooperated into larger scale applications in the building service industry like dehumidification or damping proof. The electroosmotic flow inside a porous medium is validated experimentally to further understand the dehumidification mechanism of combined techniques. An experimental test validates that the condensation from the porous medium can be obtained by electroosmotic force generated by external electric field, especially for specific desiccant powders like zeolite and diatomaceous earth. With a range of volts from 5 V to 20 V applying between the testing plates, the maximum flow rate through the cross section in the testing plate achieved during the peak period is 1.35 laL'min 1. These promising phenomena can act as an alternative way for energy choice in dehumidification industrial field. Further researches on new regeneration methods for solid desiccant dehumidification are required to make the system simple, energy-saving and suitable for small air conditioning units.
基金Supported by the National Natural Science Foundation of China China Energy Conservation Investment Corporation as a key project (No. 20236030).
文摘A vertical tubular desalination unit with shell and tube structure was built to perform humidification and dehumidification simultaneously on the tube and shell side of the column, respectively. The effects of several operating conditions on the productivity and thermal efficiency of the column were investigated. The results show that both the productivity and thermal efficiency of the column enhance with the elevation of the inlet water temperature. The flow rates of water and carrier gas both have optimal operating ranges, which are 10-30 kg·h^-1 and 4-7kg·h^-1 for the present column, respectively. Meanwhile, the increase of external steam flow rate will promote the productivity of the column but reduce its thermal efficiency.
文摘Solar humidification-dehumidification desalination technology has been reviewed in detail in this paper. This review would also throw light on the scope for further research and recommendations in active distillation system by humidification and dehumidification (HDH). Also in this article, a review has been done on different types of (HDH) systems. Thermal modeling was done for various types of humidification and dehumidification(HDH) distillation system. From the present review, it is found that the humidification-dehumidification desalination process HDH will be a suitable choice for fresh water production when the demand is decentralized. HDH is a low temperature process where total required thermal energy can be obtained from solar energy. Capacity of HDH units is between that produced by conventional methods and solar stills. Moreover, HDH is distinguished by simple operation and maintenance. Also from the present condensed review, it was observed that an increase in evaporator and condenser surface areas significantly improves system productivity. But prior to implementing any techniques in design improvement, it is necessary to optimize the MEH unit by optimizing its component size to understand the effect of feed water and air flow rates. Although a fair amount of simulation studies have been conducted in the past, further design simulation is required to fully understand the complicated effects of air and water flow rates, the optimum size of individual components or modules of the unit and to generate a comprehensive model for the system.
基金Supported by the National Natural Science Foundation of China and China Energy Conservation Investment Corporation as a Key Project (No.20236030).
文摘The modelling and experimental investigation of a thermally coupled humidification-dehumidification desalination process using a carbon-filled-polypropylene shell-tube column are presented.A heat/mass transfer model is established to study the correlation among productivity,thermal efficiency,physicochemical parameters (gas/liquid phase temperature,heat/mass transfer coefficient,Reynolds number etc.),and operating conditions(the temperature of feed water,the flow rates of external steam,feed water,and carrier air);at the same time,the effects of operating conditions on the productivity and thermal eficiency of the column are investigated both theoretically and experimentally,which indicate that the optimum flow rates of external steam,feed water,and carrier gas are 0.18,60,and 10kg.h- 1,respectively,and the higher the feed water temperature(≤95℃)is,the greater the productivity and the thermal efficiency will be.Furthermore,performance comparison with the previous study shows that the condensate productivity of this carbon-filled-plastic column is not lower than that of the copper column,which demonstrates the practicability and feasibility of applying such a plastic column to the humidification-dehumidification desalination process.
文摘The aim of this research was to study and design a solid desiccant dehumidification system suitable for tropical climate to reduce the latent load of air-conditioning system and improve the thermal comfort. Different dehumidifiers such as desiccant column and desiccant wheel were investigated. The ANSYS and TRASYS software were used to predict the results of dehumidifiers and the desiccant cooling systems, respectively. The desiccant bed contained approximately 15 kg of silica-gel, with 3 mm average diameter. Results indicated that the pressure drop and the adsorption rate of desiccant column are usually higher than those of the desiccant wheel. The feasible and practical adsorption rate of desiccant wheel was 0.102 kgw/h at air flow rate 1.0 kg/min, regenerated air temperature of 55?C and at a wheel speed of 2.5 rpm. The humidity ratio of conditioning space and cooling load of split-type air conditioner was decreased to 0.002 kgw/kgda (14%) and 0.71 kWth (19.26%), respectively. Consequently, the thermal comfort was improved from 0.5 PMV (10.12% PPD) to 0.3 PMV (7.04% PPD).
基金supported by Singapore Membrane Technology Centre(SMTC),Interdisciplinary Graduate Programme,Nanyang Environment and Water Research institute and Nanyang Technological university for this research.
文摘This review compares the different types of membrane processes for air dehumidification.Three main categories of membrane-based dehumidification are identified–membrane contactors using porous membranes with concentrated liquid desiccants,separative membranes using dense membrane morphology with a pressure gradient to drive the separation of moisture from air,and adsorptive membranes using nanofibrous membranes which adsorb and capture moisture to realise dehumidification.Drawing upon the importance of dehumidification and humidity control for urban sustainability and energy efficacy,this review critically analyses and recognizes the three unique categories of membrane-based air dehumidification technologies.Essentially,the discussion is broken into three sections-one for each category-discriminating in terms of the driving force,membrane structure and properties,and its performance indicators.Readers will notice that despite having the same objective to dehumidify air,the polymers used amongst each category differs to suit the operating requirements and optimize dehumidification performance.At the end of each section,a performance table or summary of dehumidifying membranes in its class is provided.The final section concludes with a comparative review of the three categories on membrane-based air dehumidification technologies and draw inspiration from parallel research to rationalise the potential and innovative use of promising materials in membrane fabrication for air dehumidification.
基金The National Key Technology Support Program(2015BAJ03B01)the Hunan Provincial Innovation Foundation for Postgraduate Studies(CX20190287)。
文摘Temperature and humidity independent control(THIC)air-conditioning system is a promising technology.In this work,a novel temperature and humidity independent control(THIC)system is proposed,namely VMD-ACERS,which integrates vacuum membrane-based dehumidification and air carrying energy radiant air-conditioning system.This work establishes a novel coefficient of performance(COP)model of VMD-ACERS.The main parameters affecting the COP of conventional fan coil unit cooling system(FCUCS)and VMD-ACERS are investigated.The performance of FCUCS and VMD-ACERS are compared,and the energy-saving potential of VMD-ACERS is proved.Results indicate that,for FCUCS,the importance ranking of parameters is basically stable.However,for VMD-ACERS,the importance ranking will be affected by FCU and refrigerant.The most important parameters of VMD-ACERS are condensation temperature and permeate side pressure.On the contrary,superheating,subcooling are relatively less important parameters.For VMD-ACERS,it is not necessary to pursue the membrane with very high selectivity,because the selectivity of membrane would also be a less important parameter when it reaches 500.The COP of VMD-ACERS is higher than that of FCUCS when the permeate side pressure is higher than 8 k Pa.The VMD-ACERS solves two technical problems about power-saving and thermal comfort of conventional THIC,and can extend the application of THIC air-conditioning system.
文摘Most of the desalination technologies consume a huge quantity of energy resulting from petroleum products in the form of heat or electrical energy. Solar desalination is a promisingly sustainable freshwater production technology. Solar desalination humidification dehumidification process showed the best approach as it is of the highest overall energy efficiency. In this review paper, a detailed study of the previous work is performed on solar humidification dehumidification desalination techniques experimentally and theoretically. Also in this review, different types of HDH systems were mentioned. The review showed that the humidification dehumidification desalination systems are suitable for decentralized demand. On the other hand, capacity of HDH units is not as large as conventional methods or small as solar stills. Finally, this study threw light on the scope of the parameters which have a considerable influence on increasing the freshwater output of the HDH systems as feed water flow rate, air flow rate, and design of the evaporator, condenser, and packing material. A brief economical study and a comparison of the costs per liter are performed for various humidification dehumidification desalination systems presented in this study.
基金National Science and Technology Support Program of China ( No. 2009BAG15B01)Key Pro-grams for Science and Technology Development of Chinese Transportation Industry( No. 2008-353-332-170)
文摘The necessity of the main cable anticorrosion for suspension bridge is described, and operating principles and composition of main cable dehumidification system are analyzed. An idea using the waste heat of high temperature outlet air of dehumidification system to heat up regeneration air of rotary-type dehumidifier is put forward in this paper. The concrete scheme is to install a heat exchanger on air-out pipeline of roots blower and air-in pipeline of regeneration electric heater of rotary dehumidifier. Air preheated by the heat exchanger enters regeneration electric heater of rotary-type dehumidifier. Energy conservation of main cable dehumidification system for the Yangtze River highway bridge is calculated, and the results show that energy conservation rate can reach 44 %.
基金Supported by National Natural Science Foundation of ChinaChina Energy Conservation Investment Corporation as a key project(No.20236030) .
文摘The polypropylene tubes with surface modification were installed in a baffled shell-tube column to conduct the thermally coupled humidification and dehumidification desalination process. The effects of several operating parameters (feed water temperature, water flow rate, carrier air flow rate, and external steam flow rate) on the productivity and thermal efficiency of this column were investigated experimentally. The results show that the feed water temperature has a positive effect on the productivity and thermal efficiency, while the flow rates of external steam, feed water,and carrier air should be optimized within the ranges of 0.006—0.020 kg·m-2·s-1, 0.005—0.015 kg·m-1·s-1, and 0.7—1.3 kg·m-2·s-1, respectively; the flow rates of feed water and carrier air are greatly controlled by the wetting state of the tubes. In comparison with the previous desalination column installing the coppery tubes, the present column can reach nearly the same production capacity of distilled water, which demonstrates the feasibility of applying such a plastic column to the humidification and dehumidification desalination process.
基金Ministry of Communications and Provincial and Joint Research Project[2008-353-332-170].
文摘To calculate the flow resistance of a main cable dehumidification system,this study considers the air flow in the main cable as the flow in a porous medium,and adopts the Hagen–Poiseuille equation by using average hydraulic radius and capillary bundle models.A mathematical derivation is combined with an experimental study to obtain a semi-empirical flow resistance formula.Additionally,Fluent software is used to simulate the flow resistance across the main cable relative to the experimental values.Based on the actual measured results for a Yangtze River bridge,this study verifies the semi-empirical formula,and indicates that it can be applied in actual engineering.
基金Supported by Hunan Province Science and Technology(2007FJ1012)the Scientific Research Fund of Hunan Provincial Education Department(09CY014)Doctoral Fund of HNUST
文摘In order to improve the thermal environment of high-temperature heading face,moisture content of supply air is reduced by dehumidification, and the relative humidity ofenvironment air of the heading face is also decreased.First, according to the coefficient ofperformance of dehumidifier, the capacity of dehumidification was calculated.Second, inthe engineering example of the heading face, quantitative changes of WBGT (Wet BulbGlobe Temperature) were compared between with dehumidification and without dehumidification.Based on WBGT standards, the thermal comfort of high-temperature environmentof heading face was evaluated between with dehumidification and without handling.Reducingthe relative humidity of airflow through dehumidification, the thermal comfort of ahigh-temperature environment of heading face can improve greatly.Even if dry bulb temperatureof airflow is not decreased, the thermal comfort of heading face environment isalso improved to some extent.
基金supported by the National Natural Science Foundation of China(9112502531400319)
文摘Atmospheric water absorption by plants has been explored for more than two centuries, and the aerial parts of plants, particularly the leaves of certain species, have been demonstrated to have an ability to absorb and utilize saturated atmospheric water such as fog, dew and condensed water. So far, however, there have been few studies on the aerial parts of desert plants in their absorption of unsaturated water from the atmosphere. This study presents an ultrasonic humidification fluorescent tracing method of detecting unsaturated atmospheric water absorption by the aerial parts of desert plants. We constructed an organic glass room based on the sizes of field plants. Then, the aboveground parts of the plants were humidified in the sealed glasshouse using an ultrasonic humidifier containing fluorescent reagents. The humidity and wetting time were controlled by turning on or off the humidifier according to the reading of a thermo-hygrometer suspended in the glasshouse. Fluorescence microscopy was employed to observe these plant samples. This method can generate unsaturated atmospheric water vapor and incorporate other fluorescent reagents or water-soluble chemical reagents for gasified humidification. In addition, it can identify plant parts that absorb unsaturated atmospheric water from the air, detect water absorption sites on the surface of leaves or tender stems, and determine the ability of tissues or microstructure of aerial parts to absorb water. This method provides a direct visual evidence for the inspection of leaf or tender stem microstructure in response to unsaturated atmospheric water absorption. Moreover, this method shows that aqueous pores in the cuticles of leaves or tender stems of desert plants are large enough to allow the passage of ionic fluorescent brightener with a molecular weight of up to 917 g/mol. Thus, this paper provides an important approach that explores the mechanism by which desert plants utilize unsaturated atmospheric water.
文摘Indoor air quality has a direct impact on human health. Indoor air quality has aroused great concern. This experimental study compares the effects of different water humidification on the indoor particulate pollution characteristics, and analyzes the mass concentration and the particulate number concentration distribution of different sizes of particulates with time under each condition of the purified water humidification, the tap water humidification and the cold boiled water humidification in the office. The results show that under the three kinds of wetting conditions, the concentration of the fine particulates is higher. More minerals are contained in the tap water and the cold boiled water, so the two kinds of humidification have more significant impact on indoor particulate matter. But the purified water humidification has nearly no significant effect on it. The calcium and magnesium ionic compounds are partly removed after the water boiled, so the cold boiled water humidification has less impact on the indoor particulate matter than the tap water humidification. The mass concentration and particulate number concentration of the particle may also be affected due to the frequency of ultrasonic vibration.
基金Supported by the Natural Science Foundation of Jiangsu Province (BK97124) the National Natural Science Foundation (No. 20376032)+1 种基金 the Outstanding Youth Fund of National Natural Science Foundation (No. 29925616)Key Fund of National Natural Science Fo
文摘Humidification is an important step in humid air turbine system. The calculation on humidification is carried out at 423.15—573.15K, 5—15MPa. The results suggest that to produce high-enthalpy moist air, high water temperature and large water flow are needed. The water temperature is the most sensitive parameter to the humidification tower. And it is better for the humidification tower to work at temperature higher than 523 K when the system pressure is higher than 5 MPa. The comparison between the model used in this paper and ideal model shows that the ideal model can be used in simulation to simply the calculation when the temperature is lower than 473 K and pressure is lower than 5 MPa.
基金supported by the Young Scholars Developing Fund of Tangshan Teacher’s College (No.06D06)the Doctoral Fund of the Schoolthe Outstanding Overseas Chinese Scholars Fund of Chinese Academy of Sciences (No.2003-1-10)
文摘A theoretical model of a humidifier of proton exchange membrane (PEM) fuel cell systems is developed and analyzed first in this paper. The model shows that there exists a strong nonlinearity in the system. Then, the system is identified using a wavelet networks method. To avoid the curse-of-dimensionality problem, a class of wavelet networks proposed by Billings is employed. The experimental data acquired from the test bench are used for identification. The one-step-ahead predictions and the five-step-ahead predictions are compared with the real measurements, respectively. It shows that the identified model can effectively describe the real system.
文摘Objective: To investigate the continuous humidification tube insertion depth of endotracheal intubation and the flow rate of the wetting effect. Methods: From October 2008 to May 2010, among 132 patients of oral and maxillofacial surgery with tracheal intubation, continuous infusion can be adjusted to the wet method;according to the wet pipe, insertion depth of the flow rate is divided into four groups, by four different depths and velocities of the wetting effect, to be analyzed. Results: B group was significantly lower than other groups satisfied with indicators of four significantly different effects of humidification. Conclusion: When continuous humidification tube insertion depth of endotracheal intubation is 10 - 12 cm, and flow rate is 15 - 20 ml/h, the wetting effect will achieve greater satisfaction.