EVAPORATION,DROP SIZE DISTRIBUTION AND ENTROPY GENERATION CHARACTERISTICS OF A LIQUID SPRAY CONTAINING DISSOLVED SOLIDS IN A CONVECTIVE MEDIUM

Theoretical studies have been made through a unified nondimenslonal numerical model to evaluate the evaporation, drop size distribution and entropy generation characteristics of an atomized spray of liquid containing dissolved solids in a uniform stream of gas at high temperature. The influence of pertinent input parameters, namely, the initial concentration, initial Reynolds number of the spray and the ratio of ambient to initial drop temperature on the evaporation, drop size distribution and entropy generation histories of the spray with its down stream distance have been established.     

HEAT AND MASS TRANSFER IN THE PLANT-SOIL-AIR SYSTEM

ABSTRACT

Combined heat transfer and evaporation dynamics are analyzed during drying of a continuously moving, porous strip which is in direct contact with a heated plate. A transient, quasi-two-dimensional model of conjugate heat transfer between a hot massive externally /internally heated plate and wet porous strip moving along the plate is developed by accounting for evaporation dynamics. The model consists of four conjugate energy conservation equations with proper boundary/interface conditions which describe the heat transfer in four distinct zones (1-electrically or indirectly heated massive metal plate, 2-thin superheated vapor film resulting from vaporization of water in the porous strip that separates hot plate and porous strip, 3-dry region of the porous strip, and 4-wet region of the porous strip). The relevant dimensiouless parameters governing the problem are identified, and results of parametric calculations are reported to gain fundamental understanding of the process.     

Equilibrium Evaporation Behavior of Polonium and Its Homologue Tellurium in Liquid Lead-Bismuth Eutectic

Experimental study using the transpiration method investigates equilibrium evaporation behavior of radionuclide polonium (²¹⁰Po) generated and accumulated in liquid lead-bismuth eutectic (LBE) cooled nuclear systems. The experiment consists of two series of tests: preliminary evaporation tests for homologue element tellurium (Te) in LBE, and evaporation tests for ²¹⁰Po-accumulated LBE in which test specimens are prepared by neutron irradiation.

The evaporation tests of Te in LBE provide the suggestion that Te exists in a chemical form of PbTe as well as the information for confirming the validity of technique and conditions of Po test. From the evaporation tests of ²¹⁰Po in LBE, we obtain fundamental data and empirical equations such as ²¹⁰Po vapor concentration in the gas phase, ²¹⁰Po partial vapor pressure, thermodynamic activity coefficients, and gas-liquid equilibrium partition coefficients of ²¹⁰Po in LBE in the temperature range from 450 to 750°C. Additionally, radioactivity concentration of ²¹⁰Po and ^210mBi vapor in a cover gas region of a typical LBE-cooled nuclear system is specifically estimated based on the obtained experimental results, and the importance of ²¹⁰Po evaporation behavior is quantitatively demonstrated.     

Evaporation modelling using neural networks for assessing the self‐sustainability of a water body

Studies addressing the self‐sustainability of water bodies are crucial from the perspective of sustainable water resources management. An artificial water body is vulnerable to drastic water level changes resulting from various hydroclimatical and geological factors. It is incumbent therefore to rigorously investigate the effects of these factors in order to assess the response of the water body, consequent to a wide range of scenarios. This study focuses on the self‐sustainability of a water body, based on the water budget approach, and taking into account various hydroclimatical and geological factors in the study area. As the available evaporation data shared a very short (~2 years) common time frame with the other variables, evaporation was modelled using regression and artificial neural network models. The study results indicated the water body would be self‐sustainable under the extreme climatical and hydrological conditions considered. While seepage exhibited substantial impacts on the storage of the water body, evaporation was found to have only marginal impacts.     

The utility of thermal satellite images and land-based meteorology to estimate evaporation from large lakes

Evaporation measurements over lakes are limited by physical constraints, logistics and financial demands. Thermal satellite images and land-based meteorology can be combined to derive evaporation rates from large lakes. The Dead Sea is a large hypersaline lake that can be used to examine the utility of thermal satellite images along with land-based meteorology to assess evaporation rates. Sea surface tmperature was retrieved for a 12-month period using band 10 onboard Landsat 8. Monthly SST was combined with nearby land-based meteorology to estimate evaporation from the sea surface using a mass transfer method and two variations of the Penman procedure. The Mass transfer gave an annual evaporation rate of 1005 mm whereas the Penman and the Priestley-Taylor methods gave 1308 and 1140 mm, respectively. These values are commensurate with extensive field measurement and theoretically derived evaporation values. Analysis shows a tradeoff between wind speed increase over the smoother lake surface and the drop in the saturation water vapor pressure deficit across the lake-atmosphere boundary. Wind speed has profound effects on evaporation differences during the warm season but diminish appreciably in the cold season when the vapor pressure deficit is small. Thermal images were able to resolve the presence of large pockets of cool water over the Dead Sea resulting from freshwater input. Modifications to evaporation caused by freshwater input to a hypersaline lake are investigated from a thermodynamic perspective. The alteration to evaporation depends on the simultaneous departure of surface temperature and the activity of the brine.     

湿法烟气脱硝Fe Ⅱ EDTA-NO液的NO真空解吸

Fe^ⅡEDTA络合湿法脱硝是一种非常具有前景的烟气脱硝工艺，其中Fe^ⅡEDTA-NO液的NO解吸对Fe^ⅡEDTA的循环利用具有重要意义。本文首次将真空解吸技术应用于Fe^ⅡEDTA/抗坏血酸（VC）混合脱硝系统。在实验室规模的反应器中，深入研究了真空度和温度等操作因素对NO解吸性能的影响。实验结果表明，Fe^ⅡEDTA-NO液的NO可以通过直接加热或真空进行解吸，真空度的大幅度上升可以显著提高解吸性能，且高温有利于NO的解吸。此外，与直接加热再生相比，真空解吸可提高解吸速率并降低总能耗。动力学结果表明，Fe^ⅡEDTA-NO的解吸过程为一级动力学，同时，Fe^ⅡEDTA-NO解吸的活化能、活化熵、活化焓分别为2.83kJ/mol、196.90J/(K·mol)、159.76kJ/mol。最后，解吸吸收循环实验过程表明，脱硝富液Fe^ⅡEDTA-NO在NO真空解吸后仍能捕获NO，而且在循环实验中，经过11个循环后，NO的平均去除率降至90%以下。     

降膜蒸发—凝结型闭式循环太阳能蒸馏系统的模拟实验研究

建立了一套采光面积为1．07m∧2、主动回收蒸汽潜热及浓海不余热降膜蒸发－凝结型闭式循环太阳能蒸馏系统,4盏卤素灯作为太阳能模拟器，对该系统进行了模拟实验研究。实验结果表明，由于在本蒸馏系统中采用了强迫降膜蒸发及降膜凝结技术，使其中大部分的蒸汽潜热以及浓盐水的显热都得到了重复利用，单位采光面积的产量相对于传统的盘式（单级）太阳能蒸馏器提高了2－3倍。     

直接蒸发式有机填料水垢形成与影响实验研究

本文通过实验研究了直接蒸发式有机填料表面污垢的形成过程及其对填料性能的影响.着重详细分析了淋水硬度、淋水流量等因素在结垢过程中的影响规律,以及污垢对填料蒸发效率和空气阻力的具体影响.实验结果表明：污垢的存在会影响填料纤维的吸水性和空气的流通性,从而降低蒸发效率和增大空气阻力,但影响过程比较缓慢.污垢沉积量在一定淋水硬度范围内随着淋水硬度的增加而增加,相反,污垢沉积量随着淋水流量的增加而减少.本次实验结果将为接下来对有机填料结垢实验的进一步研究奠定基础.     

SUPERHEATED STEAM DRYING OF SINTERED SPHERES OF GLASS BEADS UNDER VACUUM

Drying of sintered spheres of coarse glass beads with a wide sintering range in superheated steam under vacuum was studied.

In samples with sintered angles of 7.5° –27°, the experimental normalized drying rates in superheated steam at pressures of 7.3-7.9mmHg were smaller than those for 56.0-767.6 mmHg in the vicinity of the critical moisture cotents for 56.0-767.6GmmHg. As reported in an earlier paper, there were