Water Vapor Partial Pressure Research Articles

A new method for retrieving urban heat island intensity using GNSS-derived ZTD and atmospheric empirical model

ABSTRACT The urban heat island (UHI) effect is one of the typical characteristics of urban climate, which makes a lot of harmful gases accumulate and cannot be diffused. The UHI effect will cause air pollution, affecting the health and living conditions of humans. In this paper, a new method for calculating UHI intensity (UHII) by using the Global Navigation Satellite Systems (GNSS) derived zenith tropospheric delay (GNSS-ZTD) dataset and atmospheric empirical model was proposed and tested by using UHII observations from ground meteorological sensors for monitoring UHII in the Hong Kong city. The method requires accurate GNSS-ZTD datasets, priori atmospheric parameters (i.e. ground pressure and water vapour partial pressure) and the coefficient of the refractive function as inputs. The GNSS-ZTD datasets were obtained by using observations from the Hong Kong GNSS continuously operating reference stations network, and priori atmospheric parameters were obtained from a prior atmospheric model based on ERA5 (fifth-generation reanalysis dataset of the European Centre for Medium-range Weather Forecasting) dataset and the coefficient of the refractive function can be obtained from the historical radiosondes data. The ground refractivity, pressure and water vapour partial pressure can be estimated by using the above-mentioned datasets, then the time series of UHII can be obtained by using a refractivity model proposed by Smith and Weintraub (SW-UHII), or Thayer (Thayer-UHII model). The results showed that the accuracy of the SW-UHII is better than the accuracy of the Thayer-UHII, and the root mean square (RMS) of the SW-UHII is 14% lower than the RMS of the Thayer-UHII. The mean bias, RMS and standard deviation of the SW-UHII compared with meteorological data derived UHII over GNSS stations are 1.82°C, 1.9°C and 1.41°C in all seasons, respectively, and the largest RMS is in winter (day of year 1–61 and 331–365). All the above results indicated that the GNSS technique has a certain prospect for monitoring UHII.

Mass transfer study on high-pressure membrane dehumidification applied to aircraft environmental control system

Expected to replace conventional condensing dehumidification, pressure-driven membrane dehumidification is an alternative to the high-pressure air dehumidification in aircraft environmental control system (ECS). A high-pressure membrane dehumidification experiment is conducted on a counter-flow hollow fiber membrane module to investigate the dehumidification performance under various operating conditions including feed flow rate, feed pressure and sweep ratio. The experiment achieves the dehumidification rate of 1007 g/h at highest. Taking account of the variation of mass transfer driving force along the flow direction, the theoretical model reaches a good agreement with the experiment data. Based on the validated model, a numerical simulation study is conducted to explore the detailed mass transfer characteristics. The simulation reveals the outstanding distinction between the high-pressure and normal-pressure membrane dehumidification. Driven by water vapor partial pressure difference, the mass transfer in the latter one is determined by humidity ratio only, while that in the former one depends on humidity ratio and pressure altogether. Various combination modes of multiple membrane modules are also investigated for more flexible arrangement in the compact space of aircraft, and it is found that the pure parallel mode performs the best. Finally, exergy analysis is employed to compare with the condensing method. In comparison, the membrane method performs the less exergy destruction especially at low desired outlet humidity ratio.

Effect of Water Vapor and Oxygen Partial Pressure on Oxidation of Fe and Fe–Cr Alloys

Effect of Water Vapor and Oxygen Partial Pressure on Oxidation of Fe and Fe–Cr Alloys

Estimation of Water Vapor Density in Adiabatic Mixing of Cryogenic Gas and Moist Air

Concentration distribution is essential for the emergency disposal of cryogenic fuel leakage. In the dispersion process of cryogenic gas, its concentration is greatly influenced by the atmospheric water vapor. The authors have presented an adiabatic mixing model to derive the concentration of the cryogenic gas, in which the value of water vapor density is obtained by referring to the NIST database continuously. However, it is difficult to achieve fast system response times for real-time monitoring systems when calling NIST. Thus, a simple algebraic model of water vapor density with high calculation efficiency is necessary. Based on the detection of temperature and the solution of water vapor partial pressure, a calculation model was developed. For a given initial ambient temperature and relative humidity, the dew point could be solved by Qian’s correlation. By temperature comparisons of the mixture cloud, dew point, and triple point, the water vapor partial pressure can be calculated by the Goff–Gratch formulation. Then, the water vapor density during the temperature declining process can be derived via EOS. The results show that the model has high estimation accuracy, and has a close mean deviationof 0.08%to the IAPWS 95 of 0.03%. The increase in the computation efficiency was confirmed as +67% under nine testing points. The model facilitates the engineering utilization of the adiabatic mixing model for cryogenic fuel leakage monitoring.

A STUDY ON THE PREDICTION FOR DEW CONDENSATION ON PLATFORM METAL ROOFS (PART1)：ESTIMATION OF CONDENSATION AND FROST GENERATION BASED ON MOCKUP EXPERIMENTS

To solve the problem of condensation on the metal roofs of station platforms, it is necessary to estimate the surface temperature of the metal roofs and predict condensation. Therefore, we compared the measured surface temperatures obtained from experiments using flat plates with the estimated surface temperatures calculated from ambient weather conditions to confirm the validity of the estimated values. In the folded-plate experiment, the relationship between the surface temperature and the occurrence of condensation and frost on the upper and lower portions of the square chevron-shaped cross section was clarified by determining the water vapor partial pressure.

High-resolution tropospheric refractivity fields by combining machine learning and collocation methods to correct earth observation data

Signals used for Earth observation, when travelling through the atmosphere, are sensitive to refractivity; especially high spatio-temporal variations of water vapor are difficult to model and correct. Remaining unmodeled tropospheric delays deteriorate the positioning solution and therefore limit the accuracy of sensing and navigation applications. These delays are usually computed with empirical models based on ground meteorological parameters (pressure, temperature and water vapor partial pressure). However, existing models are not accurate enough for high-precision applications such as GNSS, where in consequence the so-called zenith total delay (ZTD) has to be estimated together with other unknown parameters (coordinates etc.).For decades, the Institute of Geodesy and Photogrammetry at ETH Zurich has been studying collocation methods for the modeling of tropospheric delays using meteorological parameters, successfully interpolating pointwise or integral atmospheric observations. Meanwhile, machine learning has become a widely used and valuable alternative, when big datasets are available for the training process. Indeed, we have already successfully predicted ZTDs based on meteorological parameters with an accuracy of 1–2 cm for locations (GNSS stations) already used in the training phase. However, difficulties arise to predict delays at new locations.In this work, we take a step forward in investigating the combination of machine learning algorithms and physical models used in a collocation approach to derive atmospheric delay fields at a very high resolution. Thus, without processing any GNSS data we can predict tropospheric delay fields everywhere in the area of investigation. In this paper, we firstly describe the designed architecture of the neural network, secondly, the combination of least-squares collocation and artificial neural networks for high-resolution prediction of tropospheric delays. We benefit from the complementary characteristics of these algorithms. While machine learning is capable of successfully predicting the variation of time series for given points, empirical models based on collocation are well suited for describing spatial variations within the area of investigation. Finally, we report the achieved performance for the entire territory of Switzerland (1–2 cm in terms of RMS), showing that the synergic combination of these algorithms can overcome the individual drawbacks of each method and provide more accurate delay estimates than either method individually.Datasets of 11 years, covering the territory of Switzerland, consisting of GNSS ZTDs from 72 permanent AGNES/COGEAR (swisstopo, ETHZ) stations and meteorological data from MeteoSwiss were used for this research.

Efficient Multi-Layer Wall Panel

A comprehensive analysis of the multilayer wall panel has been performed. The heat-insulating layer, the thickness of which affects both the dimensions of the enclosing structure and the heat-shielding efficiency of the wall panel, has been studied,. Reducing the thickness of the thermal insulation layer is an important issue, since the production of three-layer panels is expensive in energy and material terms. The features of using a different number of screens to reduce the size of the thermal insulation layer are presented. An example of the possibility of a maximum reduction in the size of the heat-insulating layer, when the thickness of the interlayer din cannot be less than 3–5 mm is given. It is shown that the total thickness of the thermal insulation layer will be 0.057 m in the presence of the maximum possible number of screens – 12. For these conditions, the temperatures in the enclosure planes are calculated, according to the values of which the values of the maximum partial pressures E and partial pressures of water vapor e are determined (for the variants of perforated е¢ and non-perforated е¢¢ screens). According to the obtained values the dependences E, е¢, е¢¢ on the temperature in the planes of the fence are constructed. The calculations carried out and a general assessment of the heat and humidity regime in the enclosing structures were confirmed with the help of the compiled program and the calculation of the necessary parameters е and t in the layers of the structure. It has been established that various shielding materials can be used to exclude condensation zones during the operation of enclosing structures.

ROLE OF THERMODYNAMIC PROCESSES IN PLANT LEAF GAS EXCHANGE SYSTEM FOR ASSIMILATION OF CO2 EMISSIONS FROM THE AMBIENT AIR

When temperature in the leaf gas exchange system changes, the thermodynamic parameters describing the condition of moist air also change. A temperature change of 1 oC in plant leaf tissues leads to a change in partial water vapour pressure of 144 Pa in the gas exchange cavities. Then a temperature decrease of 1 oC in a plant leaf produces 0.897 g of condensate, from 1 m3 of air in leaf ventilation cavities on the surface. When the temperature of plant leaves in the leaf ventilation system changes, the total water vapor state on the inner surface of the leaves changes, and the water vapor state in the stomatal cavities changes. The thickness of the formed condensate film on the plant leaf canal wall surfaces depends on the canal diameter and temperature change. The paper presents information about the mechanism of water formation and thermodynamic processes in the plant leaf gas exchange system participating in the process of assimilation. The formation and change of the internal surfaces of the stomatal cavities of the water film sheet allow the participation of chemical processes in the assimilation of CO2 emissions from the environment.

Experimental Investigations and Modeling of Atmospheric Water Generation Using a Desiccant Material

Harvesting atmospheric water by solar regenerated desiccants is a promising water source that is energy-efficient, environmentally clean, and viable. However, the generated amounts of water are still insignificant. Therefore, more intensive fundamental research must be undertaken involving experiments and modeling. This paper describes several experiments, which were conducted to predict and improve the behavior of water absorption/desorption by the Calcium Chloride (CaCl2) desiccant, where the uncertainty did not exceed ±3.5%. The absorption effect in a deep container was studied experimentally and then amplified by pumping air into the solution. The latter measured water absorption/desorption by a thin solution layer under variable ambient conditions. Pumping air inside deep liquid desiccant containers increased the water absorption rate to 3.75% per hour, yet when using a thin layer of the solution, it was found to have increased to 6.5% per hour under the same conditions. The maximum amount of absorbed water and water vapor partial pressure relation was investigated, and the mean absolute error between the proposed formula and measured water content was 6.9%. An empirical formula, a one-dimensional mathematical model, was then developed by coupling three differential equations and compared to experimental data. The mean absolute error of the model was found to be 3.13% and 7.32% for absorption and desorption, respectively. Governing mathematical conservation equations were subsequently formulated. The mathematical and empirical models were combined and solved numerically. Findings obtained from the simulation were compared to experimental data. Additionally, several scenarios were modeled and tested for Jeddah, Saudi Arabia, under various conditions.

Modeling the distribution of subsurface seasonal water ice with varying atmospheric conditions at northern low to midlatitudes on Mars

It is of great significance to investigate the influence of seasonally varying atmospheric conditions on Martian seasonal subsurface water ice for understanding current Martian climate and performing subsequent detections for water. In this work, the regolith thermal model combined with the water vapor diffusion model was established to predict the presence of seasonal subsurface water ice. In particular, the radiation absorbed by the surface was considered under the seasonally varying atmospheric conditions. The influences of regolith properties and atmospheric properties on seasonal subsurface water ice were investigated in detail. Moreover, considering the local seasonally varying atmospheric conditions, we analyzed the distribution characteristics of seasonal subsurface water ice at northern low to midlatitudes, including the landing site of China's Tianwen-1. In low dust Martian years, our analysis shows that the near-surface water vapor partial pressure is the main atmospheric factor affecting the seasonal subsurface water ice distribution with respect to the dust optical depth and surface pressure. Larger near-surface water vapor partial pressures are more favorable for the accumulation of seasonal subsurface water ice. In addition, the subsurface water ice at lower latitudes is more sensitive to the seasonal variations in near-surface water vapor abundances, while for higher latitudes, the thermal factor, rather than the atmospheric factors, plays a dominate role for the subsurface water ice in this region. Large-scale and long-lasting global dust storms could be favorable for the massive accumulation of seasonal subsurface water ice by further reducing daytime surface temperature and even depositing CO2 ice on the surface, especially at higher latitudes. When considering the seasonal variations in near-surface water vapor abundances, the rapid growth of seasonal subsurface water ice in northern low to midlatitude regions is mainly attributed to the desorption of summertime adsorbed water.

Phase behavior, proton concentration, and conductivity of La2Ce2O7 doped with Y, Ho, Er, Tm, or Yb

AbstractLa2Ce2O7 is a fluorite‐type oxide, showing almost pure oxide ion conduction in dry oxygen atmosphere. Under wet oxygen atmosphere, protons are introduced into La2Ce2O7 through hydration reaction, making the material proton‐conducting. However, compared with the oxide ion conductivity, the proton conductivity is negligibly small in La2Ce2O7. Here we report the effect of doping trivalent rare earth cations R3+ (R = Y, Ho, Er, Yb, or Tm) and elevating partial pressure of water vapor on the proton concentration and conductivity of La2Ce2O7. The samples show single fluorite phases with the doping level up to 0.2, and the solubilities of these dopants were within 0.2–0.3 in La2Ce2O7. The proton concentration increased by doping, due to higher amount of hydratable oxygen vacancies, and statistical coordination of oxide ions surrounded by R3+ in addition to La3+. The sample with the Y content (x) of 0.05 showed the highest conductivity at 600°C among La2(Ce1−xYx)2O7−δ (x = 0–0.3) samples, possibly due to the balance between the improved hydration ability and decreased mobility of protons with the increasing Y doping level. Then, the dopant content was fixed to 0.05, and La2(Ce0.95R0.05)2O7−δ (R = Y, Ho, Er, Tm, or Yb) was prepared. It was found that as the water vapor partial pressure increased, the proton concentration and conductivity increased regardless of the dopants. Y‐doped La2Ce2O7−δ ha the highest proton concentration and conductivity.

Comparative analysis of heat loss performance of flat plate solar collectors at different altitudes

Flat plate solar collectors (FPSC) are a vital component in the medium and low temperature utilization system of solar energy and are widely used at different altitudes throughout China. Changes in altitude can cause changes in outdoor meteorological conditions, which can affect radiation and convection heat transfer processes on the surface of FPSC. Research into the heat loss characteristics of FPSC, when used at different altitudes, is relatively inadequate. To analyze the comprehensive impact of the change in altitude on the heat loss performance of FPSC, a model for the calculation of heat losses of FPSC was developed in this study. The influence of air pressure on air convection and long-wave radiation heat transfer was considered, and the accuracy of the model was verified by experimental test data. The variation of convection heat loss (CHL) and radiation heat loss (RHL) caused by environmental conditions such as atmospheric pressure, air density, solar irradiance and water vapor partial pressure with changes in altitude is investigated using the numerical calculation method. The results show that with increasing altitude, CHL and RHL show opposite trends, with the former gradually decreasing and the latter gradually increasing. The maximum variation of CHL and RHLs as a percentage of total heat loss can exceed 50%. Two opposite processes of heat loss play a combined role in the variation of the total heat loss, resulting in a decreasing and then an increasing trend in the altitude of the total heat loss coefficient, with a maximum variation of 10%.

Analysis and Experimental Study on Water Vapor Partial Pressure in the Membrane Distillation Process.

In membrane distillation, the vapor pressure difference is the driving force of mass transfer. The vapor pressure is generally assumed by the saturation pressure and calculated by the Antoine equation. However, in the actual operation process, the feed solutions usually flow in a non-equilibrium state, which does not meet the theoretical and measurement conditions of the vapor-liquid equilibrium (VLE) state. This study tested the actual water vapor pressure of the pure water, lithium bromide (LiBr) solution, lithium chloride (LiCl) solution, and calcium chloride (CaCl2) solution under different flow conditions. The results showed that the actual water vapor pressure was lower than the saturation pressure overall, and the difference increased with temperature but decreased with the mass concentration. Therefore, in vacuum membrane distillation (VMD), air gap membrane distillation (AGMD), and sweeping gas membrane distillation (SGMD), the membrane flux calculated by water vapor saturation pressure was higher than the actual membrane flux, and the relative difference decreased and was less than 10% after 60 °C. In direct contact membrane distillation (DCMD), the water vapor pressure difference on both membrane sides was almost the same by using the saturation vapor pressure or the tested data since the pressure errors were partially offset in parallel flow or counter-flow modes.

Numerical Investigation of the Adsorption Process of Zeolite/Water in a Thermochemical Reactor for Seasonal Heat Storage

Zeolite 13X molecular sieve with high sorption capacity and significant sorption rate has been considered a promising candidate for seasonal heat storage. In this study, a code is developed to simulate the adsorption process between zeolite and water in all ranges of partial pressures, temperatures, and sorbate loadings. The results from the proposed code were compared with experiments and good agreement was observed. After validation, the developed model was used to study the effective parameters involved in the adsorption process of binder-free Zeolite 13X. A parametric study considering various temperatures and water content in the inflow air was conducted and the influence of different factors on the outlet temperature and adsorption enthalpy has been studied. This parametric study gives a good insight into the measures which can be taken for achieving the desired released energy or having the outlet temperature in the preferred range. The simulations have been conducted in a variety of temperature ranges provided during the desorption process, the humidity amount, and the mass flow rate of the incoming air. The relative influence of each parameter in the specified ranges is presented. The results have demonstrated the direct relationship of the partial pressure of water vapor and the desorption temperature with the adsorbed water amount and adsorption enthalpy while changing the mass flow rate mostly influences the discharging time.

Effects of biological crusts on soil organic carbon in sandlands under a precipitation gradient

Biological crusts (Biocrusts) are important surface active coverings in arid and semi-arid regions, which affect the content of soil organic carbon (SOC), SOC labile fractions and stability of SOC through photosynthetic carbon fixation. At present, studies on the variation characteristics of SOC, SOC labile fractions and the stability of SOC in biocrusts are rather limited. In this study, two types of typical biocrusts (moss crusts and algae crusts) were selected along a precipitation gradient from northwest to southeast in the Mu Us Sandland (straight line distance 188 km) by measuring soil organic carbon (SOC), soil microbial biomass carbon (MBC), water soluble carbon (DOC), particulate carbon (POC), easily oxidizable carbon (ROC). We aimed to explore the effects of biocrusts on the stability of SOC and carbon decomposition across the precipitation gradient. Results showed that:1) Two types of biocrusts significantly increased the contents of SOC, MBC, DOC, POC, ROC and stability of SOC. Moss crusts increased SOC contents by 1.6 to 2.6 times as that of algae crusts. 2) The lowest SOC contents of the two types of biocrusts were 6.43 g·kg-1 and 14.50 g·kg-1 respectively, which showed an increasing trend with increasing precipitation along the gradient. 3) With the increases of precipitation, the decomposition time of moss litters gradually decreased. The decomposition coefficient of moss litters during the study period (From July to Feb-ruary of the next year) ranged from 0.010 to 0.014, which was significantly lower than that of vascular plants. The carbon release of moss litters from northwest to southeast was 8.09, 10.89, 12.88 g·kg-1, respectively. 4) Results of canonical correspondence analysis showed that water vapor partial pressure, actual evapotranspiration, annual average temperature, subsurface short-wave radiation, potential evapotranspiration and vapor pressure difference were the key climate factors affecting the content of SOC and its active components. Silt content was the main soil factor affecting the content of SOC and its active components.

High-temperature transport properties of BaSn1−xScxO3−δ ceramic materials as promising electrolytes for protonic ceramic fuel cells

Protonic ceramic fuel cells (PCFCs) offer a convenient means for electrochemical conversion of chemical energy into electricity at intermediate temperatures with very high efficiency. Although BaCeO3- and BaZrO3-based complex oxides have been positioned as the most promising PCFC electrolytes, the design of new protonic conductors with improved properties is of paramount importance. Within the present work, we studied transport properties of scandium-doped barium stannate (Sc-doped BaSnO3). Our analysis included the fabrication of porous and dense BaSn1−xScxO3−δ ceramic materials (0 ⩽ x ⩽ 0.37), as well as a comprehensive analysis of their total, ionic, and electronic conductivities across all the experimental conditions realized under the PCFC operation: both air and hydrogen atmospheres with various water vapor partial pressures (p(H2O)), and a temperature range of 500–900 °C. This work reports on electrolyte domain boundaries of the undoped and doped BaSnO3 for the first time, revealing that pure BaSnO3 exhibits mixed ionic-electronic conduction behavior under both oxidizing and reducing conditions, while the Sc-doping results in the gradual improvement of ionic (including protonic) conductivity, extending the electrolyte domain boundaries towards reduced atmospheres. This latter property makes the heavily-doped BaSnO3 representatives attractive for PCFC applications.

Methods for Constructing and Properties of Unified and Individual Pressure Diagrams “Enthalpy - Moisture Content” of Compressed Air

In engineering practice, when determining the characteristics of atmospheric air, I-d Ramzin diagrams are widely used, developed for a certain average barometric pressure. Direct transfer (without recalculation) of characteristics from atmospheric I-d diagrams to compressed air leads to serious errors. For compressed air, only individual and unified pressure I-d diagrams are applicable. Research objectives: creation of working (up to the level of algorithms) methods for constructing such I-d diagrams and establishing the boundaries of their applicability to air in a different state and at a different pressure. To construct I-d diagrams of compressed air, the atmospheric I-d diagram field is used. Humid air is assumed to be an ideal gas, the enthalpy of which does not depend on pressure. Isotherms and isoenthalps are copied from atmospheric I-d diagrams with their scale preserved. Also, the graph of the partial pressure of water vapor is copied, but its scale changes in proportion to the ratio of compressed air pressure to the accepted barometric pressure. Section 1 gives an algorithm for constructing pressure-individual I-d diagrams with a grid of curves of constant relative humidity. A method is given for determining at a given point such an I-d diagram of relative air humidity for a different pressure. This technique makes it possible to depict compressed air relative humidity curves on an atmospheric I-d diagram. For practical problems with the condensation of compressed air water vapor, it is convenient to use I-d diagrams unified by pressure, which are distinguished by the presence of a grid of saturated air relative humidity curves for a number of pressure values. Section 2 provides an algorithm for constructing unified I-d diagrams and gives a method for determining the relative humidity of unsaturated air at pressure P at a given point of such a diagram. The paper gives examples of the application of this technique.

Mathematical model for computer simulation for selection of the order for the layers from the wall of industrial coolers

A mathematical model and computer software was developed for calculating the thickness of the insulation layers (panels) from the walls of the industrial coolers based on the order of their installation. A numerical example is given that is tested on an existing industrial cooler in Bitola, Macedonia. In order to calculate the thickness of the thermal insulation it is necessary to consider a multilayer barrier (wall) where for each layer the thickness is known, except for the insulation material which should be calculated. With the determined geometric and physical characteristics of the wall, it is necessary to determine the temperature at each point of the construction. By connecting these points, the temperature change through the construction creates dependency with its thickness. After calculating the actual specific heat flux, the temperatures between each layer of the wall are calculated. For improved monitoring of the change in the partial pressure of the saturated water vapor through the layers of the wall, the thickness of the insulating material is divided into approximately five parts, and then a table of temperature changes and the corresponding value of the partial pressure of the saturated aqueous vapor is created. In order to avoid condensation of the water vapor when it passes through the wall, a certain condition must be fulfilled. With certain measurements adopted, a computer simulation was created and measurementes calculated. The computer simulation enables swift and accurate calculation of thickness of the insulation at multilayer bulkheads found at industrial coolers, and allows selection of the location for the insulation and steam barrier in the bulkhead.

The impact of climate change on evaporation from the water surface in Ukraine


 
 
 
 Based on the monitoring data, the features of long-term changes of evaporation from the water surface are determined. Data from relatively small evaporators and evaporation basins located in different regions of Ukraine were processed. It was found that during the first part of the observation period, which began in the 1950s, evaporation had the tendency to decrease, while in the second part it increased significantly. To determine the factors of these changes, the existing calculated dependences were analyzed. In most of them, evaporation is determined by three arguments: the partial pressure of saturated water vapour, which corresponds to the water temperature, the actual water vapour pressure, and wind speed. It was determined that the main factor of the modern increase in evaporation is the increase of water temperature, which is accompanied by a significant increase in the partial pressure of saturated water vapour. In particular, the mean water temperature in the Dnipro Reservoirs in May– September during 1977–2020 increased at an average rate of 0.65–0.70 °C per decade, and the air temperature at 0.75 °C per decade. It is important that the relationship between water temperature and the partial pressure of saturated water vapour, which corresponds to it, is nonlinear. Wind speed does not significantly affect evaporation. In addition, in recent decades there has been a tendency to its decrease. An empirical dependence of evaporation on air temperature is proposed. Its nonlinear form indicates a significant increase in evaporation due to the temperature increase. Currently (1991–2020), evaporation from the water surface near Kyiv during the ice-free period is approximately 650 mm, in the south of Ukraine it reaches 1000 mm. The increase in evaporation results in additional water losses and a reduction in available water resources.
 
 
 

A new moisture control method: Analysis of dynamic changes of temperature and moisture in coal particles during drying

The vapor–solid double split moving bed dryer compared to other dryer achieves the purpose of uniform drying of particles and higher drying efficiency. Aiming at theoretical blind spots and technical errors in this technology, a small drying device with stirring was set up in the laboratory to simulate the interface update of coal in the moving heating surface, and the dynamic changes of temperature and moisture during the drying period. Then the changes of coal particle characteristics after drying was tested and analyzed to evaluate the effect of these changes and storage conditions on water re-absorption during dry coal storage. The results indicate that interface update, drying temperature and particle size were three main factors that affect the drying rate of coal. The higher drying temperature will cause the shrinkage and collapse of the macropores and mesopores, this reduces the water re-absorption rate of dry coal during later storage in bunker. The reasonable stirring speed can not only meet the interface renewal rate of coal heating surface, but also protect the structure of large particles from being destroyed. Finally, the increase of ambient temperature and partial pressure of water vapor also can reduce the water re-absorption.