Measurement of Tritiated Moisture in Gas Stream by Collection Method Using P2O5 Desiccant

A measurement method of tritiated moisture in gas stream has been developed by taking advantage of the high hygroscopic and deliquescent performances of phosphorus pentoxide P₂O₅. The method includes two techniques; one is of collecting moisture from gas stream using the desiccant, the other is of preparing homogeneous liquid scintillation cocktails containing the phosphide and the collected moisture. By introducing an idea of common use of standard vials as the collector cells disposable and the scintillation cocktail containers, the treatment process has been simplified and the chances of error arising in process for subsequent tritium analysis have been decreased. From results of a typical experiment, a relationship between the collection efficiencies and the moisture contents of P₂O₅ has been obtained and the isotope effect on the moisture collection has been elucidated. The collecting performance and the isotope effect are discussed here considering the mass transport phenomena in collector cell.     

液体除湿空调系统的除湿器性能试验

以实际液体除湿空调系统为对象,对其进行实验研究,改变系统中除湿器入口空气及溶液的参数,得出空气出口温、湿度随之变化的状况。并与理论模拟计算值比较,获得实验值和理论值有相同的变化趋势的试验数据。实验得出在诸多的入口参数中,溶液的温度和流量的变化对空气出口温、湿度影响较大,空气的出口温度实验值偏小于理论值,空气的出口湿度实验值偏大于理论值。试验结果可对液体除湿空调系统的性能分析和设计提供帮助。     

Investigation of the effect of ambient conditions on the performance of solid desiccant cooling cycles

The operation of desiccant air-conditioning systems is characterised by processes implemented to the moist air of the environment; it is, thus, expected to be affected by ambient conditions. The present work aims at quantifying this influence on the basis of an easy-to-implement, steady-state model of the system, presenting an efficiency factors approach, which has been experimentally validated. The analysis examines the behaviour of the ventilation and the recirculation cycles, which constitute the marginal cases regarding the achieved values of the outside air fraction, given the ambient conditions, the desired regeneration temperature and the efficiency of the involved components. The fact of a desiccant cycle undergoing a set of changing ambient conditions by its actual operation is also considered in the analysis. The results provide useful information for the selection of the optimum configuration to the designer of a desiccant air-conditioning system.     

Water Content of Natural Gas in Equilibruim with Water

A new model for predicting water content of natural gas in equilibrium with water is obtained. This formula is a function of pressure and temperature and is applied within a wide range of temperatures and pressures. This new formula shows good data fit, with an average absolute error of 4.2 for 164 data points.     

Thermodynamic analysis of liquid desiccants

Liquid desiccants are widely used in many solar applications. In order to analyze the performance of the system using desiccant technology, the thermophysical properties of desiccants are essential. In particular, the vapor pressure of the liquid desiccant is one of the important properties in air dehumidification. In this paper, an attempt is made to predict this property based on a classical thermodynamics approach and it is found that the predicted values for lithium chloride agree very well with the experimental results. The desired sorption properties can also be obtained by mixing the desiccants, which is another method of developing a new cost-effective liquid desiccant. In this paper, simple mixing rules are used to predict the vapor pressure, density, and viscosity of the desiccant mixture, namely calcium chloride and lithium chloride. It is found that the interaction parameter need not be included in calculating the density and vapor pressure of the above mixture but must be included in predicting the viscosity.     

Water Content of Natural Gas in Equilibruim with Water

Abstract:

A new model for predicting water content of natural gas in equilibrium with water is obtained. This formula is a function of pressure and temperature and is applied within a wide range of temperatures and pressures. This new formula shows good data fit, with an average absolute error of 4.2 for 164 data points.     

Dehydration of Pollock Skin Prior to Gelatin Production

ABSTRACT: Alaska pollock (Theragra chalcogramma) is the U.S.A.'s largest commercial fishery, with an annual catch of over 1 million tons. During pollock processing, the skins are discarded or made into fish meal, despite their value for gelatin production. The absence of gelatin-processing facilities in Alaska necessitates drying of the skins before transport to decrease the moisture content, but conventional hot-air drying is expensive. This study evaluated a less energy-intensive technology, the use of desiccants for reducing water weight in pollock skins prior to shipment. To ensure that the functional properties of gelatin obtained from dried pollock skins were not affected during desiccation, gelatins were prepared from each skin-drying treatment and compared with gelatin extracted from air-dried pollock skins. None of the desiccation treatments decreased the gel strength of pollock skin gelatin, nor were there major differences in gelling temperature or viscosity among the gelatin solutions. This suggests that pollock skins can be economically stabilized for transport to a gelatin-processing facility through the use of regenerable desiccants that are already common in the food industry. Practical Application: Pollock skins destined for gelatin production can be stabilized using chemical desiccants prior to shipment. The dehydration process does not harm the functional properties of gelatin, such as gel strength, gelling temperature, and viscosity. This research suggests that fish skins can be economically stabilized for transport to a gelatin-processing facility through the use of regenerable desiccants that are already common in the food industry.     

Influences of Gas Stream Conditions on Efficiency of Tritiated Moisture Collection with P2O5-Desiccant and Isotope Effect

A method was proposed previously for collection and measurement of tritiated moisture in gas stream using P₂O₅-desiccant. Influences of the gas humidity, the gas flow rate and the distance between gas nozzle and P₂O₅-desiccant layer surface on the moisture collection efficiency have been examined through experiments, and the isotope effect on the collection has been investigated. The collection efficiency is the ratio of collected to supplied moisture, and the moisture supplying rate is in proportion to the humidity and flow rate of feed gas. The experiments show that; the collection efficiency does not depend on the gas humidity, but is affected by the gas flow rate and by the nozzle-layer distance. The effects of the flow rate and the nozzle position are related to the mass transfer distance from the bulk of gas stream to the desiccant layer surface in the collection cell. The moisture collecting rate is promoted by the approach of the gas stream to the layer surface. An expression of effective separation factor has been derived to explain the isotope effect on the moisture collection. Experimental data distribution of the separation factor have been reasonably simulated by the analysis.     

液体除湿空调测控系统研制

以液体除湿空调系统为对象,设计搭建1套全自动测试控制系统,完成其庞大的数据采集任务及相关的输入输出控制。测量系统硬件部分集合数据采集单元和相关测量仪器,软件部分以VB6.0为开发平台,配合MicrosoftAccess数据库。控制系统用PLC作为下位机进行现场控制,通过触摸屏输入开关、频率、温度等信号,实现对使用的热源温度,风速,流量等进行精确的调节。实验证明测控系统很好地完成了液体除湿空调系统要求的数据采集及控制任务。     

A feasibility study of a solar desiccant air‐conditioning system—Part I: psychrometrics and analysis of the conditioned zone

A desiccant dehumidifier in conjunction with evaporative coolers can reduce air conditioning operating costs significantly since the energy required to power a desiccant cooling system is small and the source of this required energy (solar, waste heat, natural gas) can be diverse. Such a solid desiccant cooling system with a backup vapour compression system is simulated and the performance of the system is evaluated to study its feasibility in four cities in the United States. This paper describes the relevant psychrometric calculations and analyses of the conditioned zone required for simulating the transient performance of the system. Copyright © 1999 John Wiley & Sons, Ltd.