热流法计算高温炉内辐射传热

高温炉内的辐射传热是工业生产中常遇到的问题。过去，人们在应用热流法计算辐射传热时遇到了一定的困难，使计算结果与实际有一定的偏差。本文运用文献［１］中给出的新热流数学模型，开发出由新热流方程与能量方程相耦合的计算机程序，其中的比热流参数由线加热热源情况下计算得到。用该程序计算了实验室用马弗炉内的温度场，并且用热电偶实测了炉内的一些温度值，理论计算与实测值符合很好。     

气体绝缘封闭电器的高速瞬变过程和现场试验

随着ＧＩＳ的工作电压不断提高和发展，一系列新的现象和问题也同时出现。从国外一些科研，设计，制造部门所研究发表的内容看，大致有隔离开关操作和高速瞬变过程，粒子影响和对干扰定位的技术，元件的监督，现场试验等课题，本文对以上问题加以综合介绍。     

Impact of uncertainties on estimations of heat pump cycle performance

Sensitivity analysis is used to show how uncertainties in basic factors, such as heat transfer, pressure drop, compressor efficiency, and thermophysical properties, influence the result of heat pump cycle performance estimations. By comparing the results of this analysis with uncertainty levels of estimations and experimental determinations, it is established to what extent improvements in accuracy are needed. The investigation was carried out for several different applications and, as working fluids, both pure substances and non-azeotropic mixtures were examined. It was found that evaporation heat transfer and compressor efficiency are two areas where improvements are needed. It is also shown that estimates using very accurate, substance-specific, equations of state differ from those using more general types by up to 1 % for COP and 2% for capacity.     

Power Dissipation in Spintronic Devices Out of Thermodynamic Equilibrium

Quantum limits of power dissipation in spintronic computing are estimated. A computing element composed of a single electron in a quantum dot is considered. Dynamics of its spin due to external magnetic field and interaction with adjacent dots are described via the Bloch equations. Spin relaxation due to magnetic noise from various sources is described as coupling to a reservoir. Resulting dissipation of energy is calculated and is shown to be much less than the thermal limit, ∼kT per bit, if the rate of spin relaxation is much slower than the switching rate. Clues on how to engineer an energy efficient spintronic device are provided.     

Comparative studies on Ar and He closed-cycle MHD power plants combined with fossil fuel

Comparative studies on Ar and He closed-cycle MHD power plants combined with fossil fuel are performed. The sizes of a regenerative heat exchanger and a boiler are expected to be smaller for He than for Ar. The pressure loss of a working gas in a regenerative heat exchanger is reduced for He. The purification subsystem for He is expected to be more compact and economical than that for Ar; but a larger compressor is required for He than for Ar.     

Development and simulation studies of an unsteady state biofilter model for the treatment of cyclic air emissions of an α‐pinene gas stream

This paper describes the development and simulation of an unsteady state biofilter model used to predict dynamic behaviour of cyclically‐operated biofilters and compares it with experimental results obtained from three, parallel, bench‐scale biofilters treating both periodically fluctuating concentrations and constant concentrations of an α‐pinene‐laden gas stream. The dynamic model, using kinetic parameters estimated from the constant concentration biofilter, was able to predict the performance of cyclic biofilters operating at short cycle periods (ie, in the order of minutes and hours). Steady state kinetic data from a constant concentration biofilter can be used to predict unsteady state biofilter operation. At a 24 h cycle period, the dynamic model compared well with experimental results. For long cycle periods (ie, hours and days), removal efficiency decreased after periods of non‐loading: the longer the period of non‐loading, the poorer the biofilter's performance at the re‐commencement of pollutant loading. At longer time scales the model did not effectively predict transient behaviour, as adsorption and changes in kinetic parameters were not accounted for. Modelling results showed that similar biofiltration performance for the cyclic and constant concentration biofiltration of α‐pinene is expected for biofilters operating solely in the first order kinetics regime. Poorer performance for cyclic biofilters following Monod kinetics spanning the entire kinetics range is expected as the cycle amplitude increases. The most important parameters affecting the performance of a cyclically‐operated biofilter with short cycle periods are: amplitude of cyclic fluctuations, C_{g, max}/C_g, relative value of the half‐saturation constant in the Monod expression, K_s, and effective diffusivity of α‐pinene in the biofilm, D_e. Copyright © 2005 Society of Chemical Industry     

Comparison of mass transfer efficiency in horizontal rotating packed beds and rotating biological contactors

In this study, the mass transfer efficiencies of a novel horizontal rotating packed (h‐RPB) bed and the conventional disc‐type rotating biological contactor (RBC) were studied at four speeds and seven submergences. Pall rings of two different sizes (25, 38 mm), superintalox saddles and a wiremesh spiral bundle were used as packings in the h‐RPB. Volumetric gas–liquid mass transfer coefficients were determined by unsteady state absorption of atmospheric oxygen in de‐aerated water. Power consumption per unit liquid volume has been found for all geometries tested. The oxygen transfer efficiency values for the h‐RPB were found to be 2–5 kg kWh^?1 and for the disc RBC were found to be 1–2 kg kWh^?1. The performance of the h‐RPB was also compared with other gas–liquid contactors such as surface aerators. The study proves that the h‐RPB is a energy efficient alternative to conventional contactors. Copyright © 2005 Society of Chemical Industry     

Estimation of fouling in a plate heat exchanger through the application of neural networks

Pasteurization is an important, if not the most important, process step in the packaging of milk. It is subject to alterations stemming from the variation in the temperature, pH and raw milk quality. The variability may manifest itself in changes in the formation of the deposit (fouling) in the pasteurization unit, such that there is a need for tools, both instrumentation and computational, to help in monitoring the process and keeping it on the desired course. In this paper we describe a practical procedure based on artificial neural networks (ANN) that allows prediction of the deposit thickness, the overall heat transfer coefficient and the critical time (the time that the unit has to be stopped for cleaning) for reducing the impact of fouling on such processes. The procedure determines when the cleaning operation is required once the system is under critical conditions of operations. A combination of fundamental studies and plant measurements were used for study of the operating conditions and thus evaluation of the trades‐offs between operating conditions and longer operating life span. The results are encouraging, enough to validate current operating industrial techniques. Copyright © 2005 Society of Chemical Industry     

管网保温层热经济寿命的决策方法

利用保温裸露因数的概念来反映保温层保温性能的变化，提出采用统一原则来建立适用于单元系统和复合系统保温层热经济寿命的数学模型，并通过实例证明在热经济寿命终了时更新保温层，可使系统的运行具有最大的经济性。     

Material state remapping in computational solid mechanics

A computational procedure for remapping material state information from one finite element mesh to another is described. The procedure is useful in connection with evolving meshes for inelastic problems, as for example occur in the context of fracture simulation and adaptive mesh refinement. The proposed method is based on weak enforcement of equality between corresponding fields on the two meshes, where piecewise‐constant fields on both meshes are generalized from the quadrature‐point values. The essential algorithmic problem is that of calculating the volume partition of an arbitrary convex region with respect to a covering set of disjoint convex regions. Instead of geometrically resolving the associated intersections, the problem is herein approximated by a constrained optimization problem, which may be readily and efficiently solved computationally. This formulation is a main contribution of the paper. Computational examples are given that illustrate the effectiveness of the proposed procedure. Copyright © 2002 John Wiley & Sons, Ltd.