Open‐cycle OTEC systems with freshwater product: Effects of noncondensable gases on performance of condenser

An open‐cycle ocean thermal energy conversion (OC‐OTEC) system is one of the energy conversion methods used to generate electricity from ocean thermal energy. For the OC‐OTEC system, steam evaporated from the surface seawater due to flash evaporation drives the turbine. At that time, dissolved gas such as air is introduced into the low‐pressure system (OC‐OTEC system) as the noncondensable gas, which degrades the performance of condensation heat transfer. In this paper, a small‐scale OC‐OTEC experimental unit experimentally investigates the effect of noncondensable gas on the heat transfer performance in a condenser. The experimental results are discussed in comparison with theoretical estimation by the Sparrow–in method. It is shown that the condensation is occupied by heat and mass transfer near a condensation surface and that the condensation efficiency is affected by exhaust quantity of noncondensable gas at a relatively high concentration ratio of condensable gas. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 154(1): 29–35, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20179     

Effect of Channel Changes in the St. Clair River During the Present Century

Periodic man-made changes in the outlet of Lake Huron through the St. Clair River date back to the middle of the last century. These artificial channel changes have been well documented during the present century. They consist of dredging for commercial gravel removal in the upper river during 1908–25 and uncompensated navigation improvements for the 7.6-m (25-ft) and 8.2-m (27-ft) projects completed in 1933 and 1962, respectively. The total effect of these changes on the levels of Lakes Michigan and Huron (hydraulically one lake) and on the upper St. Clair River profile was determined with dynamic flow models. The ultimate effect of the above dredging was a permanent lowering of the Lake Michigan-Huron levels 0.27 m (0.89 ft), which represents a tremendous loss of freshwater resource [32 km³ (7.7 mi³)].     

生态城市与水利现代化

对天津及其滨海新区生态城市水利建设进行了分析。研究了在淡水资源极度匮乏的条件下,有效开发利用非常规水资源的必要性、重要性和现实性。认为天津市对水资源应遵循节水、治污、高效配置,妥善处理生活、生产、生态之间的关系,力求平衡调配。供水水源应是多元的,增加非常规水资源(污水、海/咸水、雨/洪水)的利用,同时增加可用地下水,外调来水等,逐步进入可持续发展配置。     

Simulation of water and nitrogen dynamics in soils during wastewater applications by using a finite-element model

A mathematical model was developed to simulate water movement, mass transport, and nitrogen transformations in soils during wastewater applications. The model is one-dimensional and based on the Galerkin finite-element method. The submodel of mass transport of nitrogen incorporates the convection-dispersion processes of ammonium and nitrate nitrogen, nitrification, denitrification, ammonium exchange and uptake of ammonium and nitrate ions. The accuracy and validity of the proposed model was examined by comparison with an explicit-implicit finite-difference model results. The model was used for simulation of water and nitrogen dynamics during wastewater application in homogeneous and multi-layered soils under different N concentration, rate, duration and scheduling of application.     

Effect of water inlet velocity on thermal stratification in a mantled hot water storage tank

Thermal stratification in a mantled hot water storage tank is analysed numerically for different water inlet velocities. The aim is to obtain higher thermal stratification and supply hot water for usage as long as possible. Twelve different water inlet velocities to the hot water storage tank are considered. The numerical method is validated by comparing its results against experimental and numerical results from the literature. It turned out that the results obtained from the numerical analysis have shown very good agreements with the results from previous works. As a result, the water temperature in the tank increases with the increase of the water inlet velocities to the mantle but this increment is not proportional. After a period of operation of 7.2 h, which corresponds to the average sunshine duration in Turkey, temperature increments of 6.5 and 35 K have been estimated for the hot water inlet velocities of 0.01 and 0.3 m s^?1, respectively, at a radial distance of 0.1 m and a height of 1 m inside the storage tank. Copyright © 2005 John Wiley & Sons, Ltd.     

Phase equilibria of quasi-binary systems consisting of multicomponent polymers 1 and 2. IV: Poly(ethylene oxide)/poly(propylene oxide) systems

To confirm the reliability of the theory of phase equibria of multicomponent polymer 1/multicomponent polymer 2 systems (i.e. quasi-binary systems) and the method of computer experiment based on this theory (Brit. Polym. J., 23 (1990)285; 23 (1990)299; Polym. Int., 29 (1992)219), could point curves (CPC), two-phase volume ratios ( R ) and critical solution points (CSP) have been determined experimentally for the quasi-binary mixtures of poly(ethylene oxide) (M¯_w = 647, M¯_w/M¯_n = 1.15; M¯_w and M¯_n, the weight-average and numberaverage molecular weights, respectively) and poly(propylene oxide) (M¯_w = 2028, M¯_w/M¯_n = 1.08; and M_w = 2987, M_w/M_n = 1.13). The hydroxyl end groups of both polymers were methoxylated in advance by the Cooper & Booth method (Polymer, 18 (1977)164). The thermodynamic interaction parameter between both polymers, χ₁₂, and the concentration dependence parameters for the above quasi-binary systems were determined by the method proposed in a previous paper (Brit. Polym. J., 23 (1990)299). CPC, R and CSP values calculated on the basis of the theory are in good agreement with the values determined experimentally.     

Dough mixing and breadmaking properties of quinoa-wheat flour blends

Flour blends of quinoa-wheat containing 0, 5, 10, 15, and 20% of manually dehulled quinoa meal or flour were evaluated for dough mixing and breadmaking properties and liking of the bread by a small panel. Increasing amounts of quinoa meal or flour increased farinograph absorption and dislike of bread for most of the panel. Dough development time increased with increase in meal but decreased with increase in quinoa flour. At 10% inclusion levels differences in liking from control 100% wheat flour bread were smaller for flour or water extracted meal to most of the panel, than with 10% non-extracted meal. This suggests that 10% inclusion of flour or water extracted meal may have potential for further investigation.     

坑道用水下堵漏剂的研制

坑道水下堵漏剂的研制包括F－1、F－2和F－3型。其中F－1是一种有机堵漏剂，它可以在水中固化；F－2是一种无机防水堵漏剂，施工方便；F－3是速凝型，它可在瞬间固化，能对坑道的涌水口进行堵漏。     

A general variance predictor for Cavalieri slices

A general variance predictor is presented for a Cavalieri design with slices of an arbitrary thickness t ≥ 0. So far, prediction formulae have been available either for measurement functions with smoothness constant q = 0, 1, … , and t ≥ 0, or for fractional q ∈ [0, 1] with t = 0. Because the possibility of using a fractional q adds flexibility to the variance prediction, we have extended the latter for any q ∈ [0, 1] and t ≥ 0. Empirical checks with previously published human brain data suggest an improved performance of the new prediction formula with respect to the hitherto available ones.