A review on eco-hydrological effects of condensation water

Almost half the world is suffering from drought at different levels. Since arid and semi-arid regions are characterized by extreme shortage and precipitation uncertainty, water availability is the most impo~.nt limiting factor in arid lands, and any additional source of moisture, such as condensation water, may have a positive impact upon the ecosystem. Therefore, extensive research has been carried out on condensation. Based on articles and relevant documents on the subject, this paper reviews systemati- cally and comprehensively the latest research achievements in several main aspects, including eco-hydrological effects of condensation water on plants, small animals, microbiotic crusts, soil moisture balance, ground water recharge and anthropo- genic utilization. History and trends of research about eco-hydrological effects of condensation water are intensively analyzed in order to summarize existing problems and offer opinions and suggestions for future study.

Feasibility of condensate water recycle of split air handling unit in Chinese University buildings

Recycling the condensate water of the air conditioner could be explored as an alternative water source to con-tribute to building the green campus.This paper explored the condensate water production through actual mea-surement based on a split air handling unit(SAHU)in a university building.Then,the statistical analysis was used to analyze the recycling feasibility and the impact factors of the condensate water production in 31 Chinese provincial capital cities to obtain the recycling potential map of the condensate water generated from a SAHU.Results showed that:(1)In the measurement,the amount of condensate water produced by a single split air conditioner was 1.6 kg from 12:40 to 13:40.Therefore,the daily output of condensate water of the air condi-tioner with the university operation schedule could reach 52.99 kg during the main air-conditioning season.(2)Among the 31 provincial capital cities in China,the largest condensate water outputs could be found in the Hot Summer and Warm Winter zone and the Hot Summer and Cold Winter zone,with an average monthly output of 1600 kg and 1100 kg,respectively.(3)Regression analysis showed that the dry-bulb temperature and dew point temperature of outdoor air had the highest positive and significant influence on condensate water production.The objective of this study is to provide theoretical guidance for the design and energy conservation evaluation of the feasibility of SAHU condensate water recycling in universities.

THE CASE STUDY ON THE EFFECT OF CO_2 IN CAVE ATMOSPHERE ON STABILITY OF SPELEOTHEM SCENERY IN YAOLIN CAVE, ZHEJIANG PROVINCE, CHINA

Because of the development of tourist activities and the facilities in the show cave, the closed system of show cave has been changed into the complicated open system. The great number of the visitors and the landscape lights give great deal of thermoenergy to the show cave system, especially the high intensive lights make the temperature nearby goes up very fast and reduce the humidity. After the visitors leaving and the lights switching off, the temperature goes down and humidity increases even upto saturation, the condensation taken place. In the dry seasons, the cave humidity is relative low, even down to 40 50 percent. The administrations of show cave rushes the water to clean the touristic trails and keep the high humidity as to protect the cave environment. Under the function of artificial readjustment, the humidity of Yaolin cave atmosphere reaches to 97-100 percent throughtout the year.

Numerical Simulation of Condensation-induced Water-hammer

Condensation induced water hammer is one kind of water hammer caused by cavity collapse, which occurs frequently in engineering pipelines and can bring about enormous damage. Due to the vapor condensation, the formation and collapse of cavity are transient and of two phase character. In order to simulate the process of cavity formation and collapse, a physical model is suggested. In the model, the cavity boundary is treated as free surface of a calculating field. A numerical solution of the Navier Stokes equation is obtained by using a modified VOF (volume of fluid) method, in which the vapor condensation is considered. With the method, formation and collapse of the cavity are described, and the highest pressure is acquired. The numerical simulation results coincide with experimental results.

Sub-picosecond chirped laser pulse-induced airflow and water condensation in a cloud chamber

Sub-picosecond chirped laser pulse-induced airflow and water condensation were investigated in a cloud chamber.The results indicate that the positively chirped sub-picosecond laser pulses generate a more uniform intensity distribution inside the plasma column, leading to a weaker airflow and an elliptic-shaped snow pile. The negatively chirped sub-picosecond laser pulses generate a spark-like intensity distribution inside the plasma column, which produces a wider range of airflow and a round snow pile. The amount of snow weight and the concentration of NO3-- are found to be dependent on the intensity distribution inside the plasma column. The visibly stronger plasma column generates much more snow and a higher concentration of NO3--. These experimental results provide a reference for sub-picosecond laser-induced water condensation in realistic atmospheric conditions.

Role of interfacial water in adhesion,friction,and wear--A critical review

Surficial water adsorption and interfacial water condensation as natural phenomena that can alter the contact status of the solid interface and tribological performances are crucial in all length scales,i.e.,from earthquakes to skating at the macroscale level and even to micro/nano-electromechanical systems(M/NEMS)at the microscale/nanoscale level.Interfacial water exhibits diverse structure and properties from bulk water because of its further interaction with solid surfaces.In this paper,the evolutions of the molecular configuration of the adsorbed water layer depending on solid surface chemistry(wettability)and structure,environmental conditions(i.e.,relative humidity and temperature),and experimental parameters(i.e.,sliding speed and normal load)and their impacts on tribological performances,such as adhesion,friction,and wear,are systematically reviewed.Based on these factors,interfacial water can increase or reduce adhesion and friction as well as facilitate or suppress the tribochemical wear depending on the water condensation kinetics at the interface as well as the thickness and structure of the involved interfacial water.

Effect of hydration on the surface basicity and catalytic activity of Mg-rare earth mixed oxides for aldol condensation

Magnesium and rare earth mixed oxides（Mg3 REOx（RE=La, Y. Ce）） were prepared and characterized by Xray diffraction（XRD）, N_2 adsorption-desorption, infrared spectra and microcalorimetry of CO_2. The results reveal that the Mg_3 CeO_x catalyst is present in the form of Mg-Ce-O solid solution,while the Mg3 LaOx and Mg_3 YO_x catalysts are probably rare earth oxides dispersed on MgO surface. As a result, among the calcined Mg_3 REO_x catalysts, the Mg_3 CeO_x catalyst presents the highest rate constant for acetone aldolization, which is well correlated to its more homogeneous distribution of basic sites. In contrary, the Mg_3 YO_x catalyst exhibit the lowest catalytic activity for acetone aldolization. Upon hydration pre-treatment, the basic properties on the surface of the Mg_3 REO_x catalysts were changed markedly. The Mg_3 YO_x catalyst after hydration treatment shows the highest amount of basic sites on catalyst surface, and then exhibits the highest activity among the hydrated Mg_3 REO_x catalysts. These results make it possible to fine-tune basic sites for acetone aldolization.