16 research outputs found

    Modelling and intelligent control of vehicle climatronic systems

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    The modelling and control method of a vehicle climatronic system, based on MATLAB/SIMULINK, is presented. In order to achieve high modelling accuracy, a developed simulation model library is introduced. The modelling approach is described and the developed models are validated with some of experimental data obtained. The models are nonlinear, independent of fluid type and based on thermo-dynamic principles. Analysis of the cooling circuit modelling and empirical real-time control models are created by using Fuzzy logic controller and Stateflow. Both of control input and output are implemented essentially at original vehicle CAN-Bus system. Feasible digital automatic control strategy basic to fuzzy theory, hardware and software solution are given. The simulation experiment is achieved with the Hardware-in-Loop technology. This control methodology is easily operated and worth applying for any further studies or methods

    Advances in Condition Monitoring, Optimization and Control for Complex Industrial Processes

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    The book documents 25 papers collected from the Special Issue “Advances in Condition Monitoring, Optimization and Control for Complex Industrial Processes”, highlighting recent research trends in complex industrial processes. The book aims to stimulate the research field and be of benefit to readers from both academic institutes and industrial sectors

    TRANSIENT MODELING OF TWO-STAGE AND VARIABLE REFRIGERANT FLOW VAPOR COMPRESSION SYSTEMS WITH FROSTING AND DEFROSTING

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    This thesis presents the development of an advanced modeling framework for the transient simulation of vapor compression systems. This framework contains a wide range of components and its modular nature enables an arbitrary cycle configuration to be analyzed. One of the highlights of this framework is the first-principles heat exchanger models with many salient simulation capabilities. Specifically, a high-order discretized model employing finite volume analysis is developed based on a decoupled approach to modeling the heat transfer and pressure drop performance of the heat exchanger. The frosting and defrosting models developed in the thesis are integrated into this heat exchanger model, allowing more accurate performance assessment of heat pumps. Meanwhile, an advanced low-order moving boundary heat exchanger model is developed with switched model representations to accommodate the changing numbers of fluid zones under large disturbances. Compared to the existing moving boundary models in the literature, this new model accounts for refrigerant pressure drop and possesses a more accurate evaluation for the air side heat transfer. Based on this modeling framework, the transient characteristics of a flash tank vapor injection (FTVI) heat pump system undergoing cycling, frosting and reverse-cycle defrosting operations are thoroughly explored. The dynamic system response when subjected to a step change in the opening of the upper-stage electronic expansion valve is also investigated. Comparison between the predictions and experimental data shows that the simulation can adequately capture the transient heat transfer and fluid flow phenomena of the system and thus demonstrating the fidelity of the models. Furthermore, a pull-down simulation for a multi-split variable refrigerant flow (VRF) air-conditioning system with six indoor units has been carried out. Control strategy that aims to maintain the indoor air temperatures at set values is proposed. The simulation test for controllability shows that the proposed control strategy is feasible to achieve the temperature control of individual zones

    A Predictive maintenance model for heterogeneous industrial refrigeration systems

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    The automatic assessment of the degradation state of industrial refrigeration systems is becoming increasingly important and constitutes a key-role within predictive maintenance approaches. Lately, data-driven methods especially became the focus of research in this respect. As they only rely on historical data in the development phase, they offer great advantages in terms of flexibility and generalisability by circumventing the need for specific domain knowledge. While most scientific contributions employ methods emerging from the field of machine learning (ML), only very few consider their applicability amongst different heterogeneous systems. In fact, the majority of existing contributions in this field solely apply supervised ML models, which assume the availability of labelled fault data for each system respectively. However, this places restrictions on the overall applicability, as data labelling is mostly conducted by humans and therefore constitutes a non-negligible cost and time factor. Moreover, such methods assume that all considered fault types occurred in the past, a condition that may not always be guaranteed to be satisfied. Therefore, this dissertation proposes a predictive maintenance model for industrial refrigeration systems by especially addressing its transferability onto different but related heterogeneous systems. In particular, it aims at solving a sub-problem known as condition-based maintenance (CBM) to automatically assess the system’s state of degradation. To this end, the model does not only estimate how far a possible malfunction has progressed, but also determines the fault type being present. As will be described in greater detail throughout this dissertation, the proposed model also utilises techniques from the field of ML but rather bypasses the strict assumptions accompanying supervised ML. Accordingly, it assumes the data of the target system to be primarily unlabelled while a few labelled samples are expected to be retrievable from the fault-free operational state, which can be obtained at low cost. Yet, to enable the model’s intended functionality, it additionally employs data from only one fully labelled source dataset and, thus, allows the benefits of data-driven approaches towards predictive maintenance to be further exploited. After the introduction, the dissertation at hand introduces the related concepts as well as the terms and definitions and delimits this work from other fields of research. Furthermore, the scope of application is further introduced and the latest scientific work is presented. This is then followed by the explanation of the open research gap, from which the research questions are derived. The third chapter deals with the main principles of the model, including the mathematical notations and the individual concepts. It furthermore delivers an overview about the variety of problems arising in this context and presents the associated solutions from a theoretical point of view. Subsequently, the data acquisition phase is described, addressing both the data collection procedure and the outcome of the test cases. In addition, the considered fault characteristics are presented and compared with the ones obtained from the related publicly available dataset. In essence, both datasets form the basis for the model validation, as discussed in the following chapter. This chapter then further comprises the results obtained from the model, which are compared with the ones retrieved from several baseline models derived from the literature. This work then closes with a summary and the conclusions drawn from the model results. Lastly, an outlook of the presented dissertation is provide

    Proceedings of the First International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics

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    1st International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Kruger Park, 8-10 April 2002.This lecture is a principle-based review of a growing body of fundamental work stimulated by multiple opportunities to optimize geometric form (shape, structure, configuration, rhythm, topology, architecture, geography) in systems for heat and fluid flow. Currents flow against resistances, and by generating entropy (irreversibility) they force the system global performance to levels lower than the theoretical limit. The system design is destined to remain imperfect because of constraints (finite sizes, costs, times). Improvements can be achieved by properly balancing the resistances, i.e., by spreading the imperfections through the system. Optimal spreading means to endow the system with geometric form. The system construction springs out of the constrained maximization of global performance. This 'constructal' design principle is reviewed by highlighting applications from heat transfer engineering. Several examples illustrate the optimized internal structure of convection cooled packages of electronics. The origin of optimal geometric features lies in the global effort to use every volume element to the maximum, i.e., to pack the element not only with the most heat generating components, but also with the most flow, in such a way that every fluid packet is effectively engaged in cooling. In flows that connect a point to a volume or an area, the resulting structure is a tree with high conductivity branches and low-conductivity interstices.tm201

    SPATIAL TRANSFORMATION PATTERN DUE TO COMMERCIAL ACTIVITY IN KAMPONG HOUSE

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    ABSTRACT Kampung houses are houses in kampung area of the city. Kampung House oftenly transformed into others use as urban dynamics. One of the transfomation is related to the commercial activities addition by the house owner. It make house with full private space become into mixused house with more public spaces or completely changed into full public commercial building. This study investigate the spatial transformation pattern of the kampung houses due to their commercial activities addition. Site observations, interviews and questionnaires were performed to study the spatial transformation. This study found that in kampung houses, the spatial transformation pattern was depend on type of commercial activities and owner perceptions, and there are several steps of the spatial transformation related the commercial activity addition. Keywords: spatial transformation pattern; commercial activity; owner perception, kampung house; adaptabilit
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