Modelling of the drying section of a continuous paper machine : a thesis presented in partial fulfilment of the requirement for the degree of Master in Production Technology at Massey University

The invention of paper in 105 A.D. was a milestone in the history of civilization and demand for paper has been increasing steadily ever since. Although it has become more and more popular to store, process and transfer information in electronic forms, paper is to date still the most common means for recording information. According to Storat (1993), production in the last twenty years has increased by more than 60 percent, while capital expenditures in the industry have grown to almost 12 percent of sales, or double the average expenditures of other manufacturing industries. This capital investment has gone towards capacity expansion and extensive rebuilds of existing mills - almost 60 percent of the existing capacity comes from modern facilities containing machines either newly installed or rebuilt in the past ten years. As a result, fossil fuel and energy consumption in this industry fell by 46 percent in the last two decades.[FROM INTRODUCTION

Pore scale 3D modelling of heat and mass transfer in the gas diffusion layer and cathode channel of a PEM fuel cell

Flooding of the gas diffusion layer (GDL) of proton exchange membrane (PEM) fuel cells can be a bottleneck to the system’s efficiency and even durability under certain operating conditions. Due to the small scale and complex geometry of the materials involved, detailed insight into the pore scale phenomena that take place are difficult to measure or simulate. In the present effort, a direct 3D microscale model of a portion of the PEM cathode channel and carbon cloth GDL is used to parametrically investigate local heat and fluid flow at the GDL’s pore scale and their effects on condensation of water vapour that leads to flooding. The 3D simulation through the microscale geometry is among the first appearing in the international literature. The Navier–Stokes, energy and water vapour transport equations are solved at steady state and in three-dimensional space for a range of inlet velocities and cloth fibre material properties, using a conjugate heat transfer approach to calculate the temperature field within the solid fibres. Psychrometric calculations are applied to provide indications of the conditions and areas most prone to condensation based on the calculated local temperatures and water vapour concentration

Amodel of the Microclimate in Porous Shade Houses

The first shade-house microclimatic model was developed based on the energy and moisture balances of four shade-house system components - the shade cloth, inside air, canopy, and soil surface. The transport is parameterized by resistances for small-scale turbulence and by intermittent refreshment for large-scale non-local gusts. The temperature and humidity in a semi-infinite shade house are predicted when the six coupled differential equations based on the energy and moisture balances are simultaneously solved. The model includes liquid-water balances for surfaces. The model requires only weather data, and, if desired, measured shade-house characterization data. Weather data for running the model, inside temperature and humidity data for verifying the model, and energy balance and turbulence data for further development of the model processes were collected in a large commercial shade house near Pahoa, Hawaii from 10 January to 25 March 1992

The application of three-dimensional mass-spring structures in the real-time simulation of sheet materials for computer generated imagery

Despite the resources devoted to computer graphics technology over the last 40 years, there is still a need to increase the realism with which flexible materials are simulated. However, to date reported methods are restricted in their application by their use of two-dimensional structures and implicit integration methods that lend themselves to modelling cloth-like sheets but not stiffer, thicker materials in which bending moments play a significant role. This thesis presents a real-time, computationally efficient environment for simulations of sheet materials. The approach described differs from other techniques principally through its novel use of multilayer sheet structures. In addition to more accurately modelling bending moment effects, it also allows the effects of increased temperature within the environment to be simulated. Limitations of this approach include the increased difficulties of calibrating a realistic and stable simulation compared to implicit based methods. A series of experiments are conducted to establish the effectiveness of the technique, evaluating the suitability of different integration methods, sheet structures, and simulation parameters, before conducting a Human Computer Interaction (HCI) based evaluation to establish the effectiveness with which the technique can produce credible simulations. These results are also compared against a system that utilises an established method for sheet simulation and a hybrid solution that combines the use of 3D (i.e. multilayer) lattice structures with the recognised sheet simulation approach. The results suggest that the use of a three-dimensional structure does provide a level of enhanced realism when simulating stiff laminar materials although the best overall results were achieved through the use of the hybrid model

Numerical simulation of one-dimensional heat transfer in composite bodies with phase change

A numerical simulation was developed to investigate the one dimensional heat transfer occurring in a system composed of a layered aircraft blade having an ice deposit on its surface. The finite difference representation of the heat conduction equations was done using the Crank-Nicolson implicit finite difference formulation. The simulation considers uniform or time dependent heat sources, from heaters which can be either point sources or of finite thickness. For the ice water phase change, a numerical method which approximates the latent heat effect by a large heat capacity over a small temperature interval was applied. The simulation describes the temperature profiles within the various layers of the de-icer pad, as well as the movement of the ice water interface. The simulation could also be used to predict the one dimensional temperature profiles in any composite slab having different boundary conditions

Modeling the thermal environment in an operating room

Comfort is important in everybody's lives, as it is not only a health subject, but also a productive issue. As environmental conditions differ accordingly to the space use, there is a direct influence of this space on human comfort. The Heating Ventilation and Air Conditioning (HVAC) Systems are a crucial way to obtain the expected air quality levels in the interior of buildings and to achieve thermal comfort. These systems ensure air renewal, pressurization, temperature control, and air humidity, being of utmost importance in healthcare facilities. Providing thermal comfort conditions and good air quality, especially in operating rooms, is a difficult task, as the environmental conditions should be suitable for medical staff performance and for patient safety, as well. In the current study, a Computational Fluid Dynamics model was developed and coupled with a thermoregulatory model of the human body to describe the fluid flow, heat transfer and mass transfer between the ventilation air and a human manikin inside an operating room. The CFD simulation solves the heat, mass and momentum conservation equations in the computation domain using a finite volume discretization method, in the ANSYS - environment. The interaction between the body and the environment is determined by the thermoregulatory model, which includes temperature and the moisture diffusion through the cloth fabrics. The combination of the human body and space ventilation models allows evaluating the influence of the main thermal comfort variables on the calculation of comfort index, such as, the PMV

Determination of convective film coefficients under simulated pyrolysate evolution

M.S

A review of solar collectors and thermal energy storage in solar thermal applications

Thermal applications are drawing increasing attention in the solar energy research field, due to their high performance in energy storage density and energy conversion efficiency. In these applications, solar collectors and thermal energy storage systems are the two core components. This paper focuses on the latest developments and advances in solar thermal applications, providing a review of solar collectors and thermal energy storage systems. Various types of solar collectors are reviewed and discussed, including both non-concentrating collectors (low temperature applications) and concentrating collectors (high temperature applications). These are studied in terms of optical optimisation, heat loss reduction, heat recuperation enhancement and different sun-tracking mechanisms. Various types of thermal energy storage systems are also reviewed and discussed, including sensible heat storage, latent heat storage, chemical storage and cascaded storage. They are studied in terms of design criteria, material selection and different heat transfer enhancement technologies. Last but not least, existing and future solar power stations are overviewed.Peer reviewe

The study on the integration of Activity Based Costing (ABC) system and six-sigma principle

Manufacturing organizations are facing much more challenges as compared to the earlier years. The important and crucial decisions have to be taken by the management in continuous basis in order to ensure the survival and competitiveness of company throughout the journey to become a successful organization. In order to make these decisions fast and correct, they need more accurate information related to financial and non-financial aspects. The conventional cost management systems, which were developed decades ago are unable to provide all information required to make right decision, justify the cost reduction and process improvements (Chen, 1996). This is because they were based on labor-intensive production system while today’s production processes are more sophisticated and faces constant changes. An alternative costing system, Activity Based Costing (ABC) has emerged to the new solution to costing system. It provides financial and non-financial information not only for product costing but also for each activity of manufacturing process. It can list and measure the cost of each activity individually in production and in supporting activities to deliver of a product or service right to customers (Sohal & Chung, 1998). ABC focuses on the activities performed to produce the products throughout the manufacturing process (Gunasekaran et al., 1999). By assigning other costs, such as marketing and administrative to cost object, ABC able to provide more accurate product costs. It helps to improve the operational performance by allocating overhead costs correctly. It provides cost information based on the actual consumption of the resources by each particular activity. The goal of ABC is to reveal cost allocation information by tracing the production costs accurately to activities and product (Gunasekaran et al., 1999). The implementation of ABC has provided many benefits, such as more accurate product costing, providing of cost behavior information and tracing resources consumptions. Realizing many benefits gain from implementation of ABC, many companies have embarked in applying ABC system. However, there are many problems and barriers they encountered during the implementation, which made some has decided to abort this system and not be able to exploit its advantages. It is the objective of this study to help foster the growth of Malaysian companies by helping them to provide better understanding,knowledge and skills to take advantage of using ABC as a tool to improve their manufacturing process. The title of the project is The Study on Integration of Activity-based Costing and Six-sigma Principle. The specific objective of the study is to determine success factors for ABC implementation in manufacturing companies based on Six-sigma process improvement principle. The focus of the study is to identify and understand the critical success factors in implementation of ABC, to identify and specified the problems and barriers and to understand their relationship with the ABC success. In order to identify, understand and formulate the proposed solution, this study will use a survey approach to get required data for further analysis. The survey will be based on mailed questionnaires to selected manufacturing industries in Malaysia. In order to formulate a comprehensive and relevant set of questionnaires, a comprehensive review of literature will be studied, followed by validation and verification process,which involved expert opinions and a pilot study. The next phase is where data from the study will be analyzed to identify areas related to the level of acceptance of ABC,the critical success factors and also to determine the relationship between the organization’s factors and the success of implementation of ABC system. The tangible outcome of this project is to provide a set of proposed guidelines and support tools for manufacturing organizations in applying Activity-based Costing for process improvement efforts as suggested by Six-sigma improvement principle