银的抗菌整理

Dohmen公司开发的Docair银整理体系,是一种安全且易于处理的抗菌整理体系,已成功应用于工业生产中.该体系可用于各类纤维的连续与间歇工艺中.即便经过剧烈洗涤之后也可达到良好的抗菌效果.该体系与其他纺织品助剂有很好的相容性,并且通常对抗菌性能没有负面影响.     

Steady-State and Transient Behavior of Two Heat Exchangers Coupled by a Circulating Flowstream

Systems consisting of two heat exchangers coupled by a circulating flowstream are studied. The systems differ in the flow configurations of the single heat exchangers. For steady-state operation, there exists a heat capacity rate of the circulating flowstream that maximizes the temperature changes of the external flowstreams. Until now, this optimum has been calculated assuming that the overall heat transfer coefficients of the heat exchangers do not depend on the mass flow rate of the circulating flowstream. In this paper, the dependence of the overall heat transfer coefficient on the mass flow rate of the circulating flowstream is taken into account. For transient operating conditions, the system response to perturbations of inlet temperatures and mass flow rates is calculated by the method of Laplace Transforms and an explicit finite difference method. The most significant features of the coupled system become apparent by considering outlet temperature transients induced by perturbations of the mass flow rate of the circulating flowstream.     

Mean Overall Heat Transfer Coefficient in Heat Exchangers Allowing for Temperature-Dependent Fluid Properties

For temperature-dependent heat transfer coefficients and heat capacities, fast approximation methods are presented for the estimation of the effective overall heat transfer coefficient. The heat transfer coefficients are calculated for two, three, or four reference temperatures. For the parallel and countercurrent flow a known method is described that uses a hypothetical fluid temperature for the iteration-free consideration of variable heat capacities. For the mixed–unmixed cross flow a previous method for temperature-dependent heat transfer coefficients is refined to allow also for variable heat capacities. For the mixed–mixed cross flow a new iterative fast design and rating method is developed that is a suitable model for special multipass shell-and-tube heat exchangers. The accuracy of the methods is tested against numerical calculations with good results.     

用伪并行遗传/模拟退火算法进行多流股换热器网络综合的研究

The multi-stream heat exchanger network synthesis (HENS) problem can be formulated as a mixed integer nonlinear programming model according to Yee et al. Its nonconvexity nature leads to existence of more than one optimum and computational difficulty for traditional algorithms to find the global optimum. Compared with deterministic algorithms, evolutionary computation provides a promising approach to tackle this problem. In this paper, a mathematical model of multi-stream heat exchangers network synthesis problem is setup. Different from the assumption of isothermal mixing of stream splits and thus linearity constraints of Yee et al., non-isothermal mixing is supported. As a consequence, nonlinear constraints are resulted and nonconvexity of the objective function is added. To solve the mathematical model, an algorithm named GA/SA (parallel genetic/simulated annealing algorithm) is detailed for application to the multi-stream heat exchanger network synthesis problem. The performance of the proposed approach is demonstrated with three examples and the obtained solutions indicate the presented approach is effective for multi-stream HENS.