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Reliability engineering is utilized to predict the performance and optimization of the design and maintenance of air conditioning systems. There are a number of failures associated with the conditioning systems. The failures of an air conditioner such as turn on, loss of air conditioner cooling capacity, reduced air conditioning output temperatures...
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Context 1
... conditioning equipment can take many forms. The method used for most singleefamily homes is a split system central air conditioner using a vapour compression cycle. This air conditioning system is composed of both an outdoor and an indoor unit. The outdoor unit is a condensing unit composed mainly of a compressor, condenser coils, and a fan. Homes that have forced air furnaces typically have an indoor evaporator coil that is embedded within or mounted above the furnace. Homes without forced air furnaces use an air handler composed of an evaporator coil and fan. An air handler (AHU), is a device used to condition and circulate air as part of a heating, ventilating, and air-conditioning (HVAC) system. An air handler is usually a large metal box containing a blower, heating or cooling elements filter racks or chambers, sound attenuators, and dampers. Air handlers usually connect to ductwork that distributes the conditioned air through the building and returns it to the AHU. Sometimes AHUs discharge (supply) and admit (return) air directly to and from the space served without ductwork. A set of refrigerant lines allows the refrigerant to circulate between the indoor and outdoor units as shown in Figure 1. Cooling is provided when the liquid refrigerant is delivered to the indoor evaporator coil. The refrigerant begins to evaporate, thus cooling the coil and the air that is blown across the coil. This cold air is blown through the home's ductwork into the living spaces. After passing through the indoor coil, the heat absorbed from the air causes the refrigerant to vaporize. The refrigerant vapour is drawn outside to the compressor in the outdoor unit. The compressor raises the pressure of the refrigerant and discharges it to the condenser coils. The refrigerant in the coils loses heat to the outside air being blown across the coils causing the refrigerant to condense to a liquid. This liquid then enters the refrigerant lines where it travels back into the home and through an expansion device, which reduces the pressure allowing the refrigerant to vaporize in the evaporative coil, and thus repeat the process. The process is summarized in Figure ...
Citations
... Frenkel and Khvatskin [5] presented a study on reliability measures assessment for the air conditioning system with rental equipment working in heavy weather conditions by using Lz-transform and stochastic processes method. As for the operational reliability, both Algarni et al. [1] and El-Berry and Al-Bossly [3] utilized Weibull and Gamma distribution to estimate the reliability of the air conditioner system based on its field data during use. The study revealed that Weibull method has performed well for decision making. ...
... They are fold catastrophe, cusp catastrophe, swallowtail catastrophe and butterfly catastrophe, respectively, whose potential functions are shown in Table 39. 3. ...
Aiming at hardware product’s reliability step change during the phase switch process, this study analyzes the factors that affect the reliability step change from the structural and nonstructural factors of the manufacturing system. The evaluation index system and evaluation model of reliability step change based on catastrophe theory are established. The degree of the reliability step change is evaluated by calculating the catastrophe membership function value of operation state of the manufacturing system. The application research results verify the validity of the evaluation model proposed in this study. The model can also be used to guide the formulation of effective measure to control product’s reliability step change during the phase switch of development process and accelerate the reliability growth.
... D'autres articles s'intéressent au retour d'expérience, c'est-à-dire à la phase opérationnelle, au niveau machine ou organe (Jiang Y-Q. et al., 1996) (Al Garni A.Z. et al., 2006) (El-Berry A. et al., 2013. ...
Le secteur du chauffage, de la ventilation et de la climatisation (Heating Ventilation and Air-Conditioning,HVAC) se doit, comme toute industrie d’envergure, de maîtriser la fiabilité de ses produits pour garantir un service optimal au client, réduire les délais de développement et maîtriser ses coûts. Pour ce faire, il est indispensable de connaitre et savoir appliquer les outils de fiabilité prévisionnelle, expérimentale et opérationnelle. Seule une méthodologie robuste permettant de définir une stratégie de qualification permet de garantir la tenue de l’objectif de fiabilité.La première partie de ce travail définit les problématiques ayant attrait à la fiabilité et fait l’inventaire des méthodes existantes dans des domaines connexes et surtout dans le domaine HVAC.Dans un second temps la méthodologie de qualification est proposée, avec un focus sur l’exploitation du retour d’expérience, la définition des objectifs de fiabilité et tous les plans d’essais possibles. Enfin, des exemples concrets mis en place chez CIAT (UTC) sont détaillées dans une dernière partie.
... No caso de um sistema reparável, quando são detectados componentes danificados ou em estado avançado de degradação, resultante de uma operação de manutenção correctiva ou planeada, a intervenção de manutenção pode passar pela reparação, caso se justifique do ponto de vista técnico ou económico, ou então como alternativa pela substituição total ou parcial dos componentes identificados [13]. De acordo com alguns autores [1,14], quando é realizado uma intervenção de manutenção a um sistema reparável, admitem nos seus modelos que a intervenção de manutenção consegue remover todo o dano acumulado pelo sistema até à data da intervenção, devolvendo-o a uma condição denominada de " tão bom como novo " , ou seja, é assumido que a manutenção é perfeita. No entanto, na prática esta premissa na maior parte das situações não é verdadeira uma vez que as intervenções de manutenção vão introduzir um aumento de fiabilidade do equipamento que se vai situar entre o estado anterior à intervenção e o estado tão bom como novo [9]. ...
... Com o objectivo de ilustrar as vantagens do algoritmo proposto, este foi aplicado a um equipamento chiller condensado a ar, responsável pela climatização de uma escola secundária localizada em Lisboa. À data da realização do estudo não se encontravam disponíveis dados históricos referentes às avarias do equipamento mencionado, pelo que se os dados referentes às falhas de um chiller, retirados de El-Berry e Al-Bossly [14]. ...
Given the inherent difficulties of develop preventive maintenance plans appropriate to the use of equipment, this paper presents a methodology based on the minimum cost criterion for determining the optimal intervals of preventive maintenance as a function of the equipment use. The optimization of the model developed was carried out through the use of genetic algorithms, and their implementation was performed using the computing platform Matlab. To facilitate the interface between the user and the computer platform implemented a graphical user interface was developed using the visual interface tool (GUIDE) available in the Matlab computing platform. In order to assess the robustness of the proposed methodology, it was used as a case study a condensed chiller equipment to air, responsible for the air conditioning of a secondary school and presented the corresponding results obtained and made its critical analysis. The results obtained allow us to predict the success of the proposed methodology in the definition of preventive maintenance plans of equipment depending on its use, minimizing its cost. Resumo Dadas as dificuldades intrínsecas à elaboração de planos de manutenção preventiva adequados à utilização dos equipamentos, este artigo apresenta uma metodologia baseada no critério do custo mínimo para determinar os intervalos óptimos de manutenção preventiva em função da utilização do equipamento. A optimização do modelo desenvolvido foi realizada recorrendo à utilização de algoritmos genéticos, tendo a sua implementação sido efectuada utilizando a plataforma computacional Matlab. Para facilitar a interface entre o utilizador e a plataforma computacional implementada foi desenvolvida uma interface gráfica utilizando a ferramenta de interface visual (GUIDE) disponível na plataforma computacional Matlab. Com o objectivo de avaliar a robustez da metodologia proposta, foi utilizado como caso de estudo um equipamento chiller condensado a ar, responsável pela climatização de uma escola secundária, sendo apresentados os correspondentes resultados obtidos e efectuada a sua análise crítica. Os resultados obtidos permitem antever o sucesso da metodologia proposta na definição de planos de manutenção preventiva de equipamentos em função da sua utilização, minimizando o seu custo.
With an aim to minimize the difference of use reliability of air conditioning (AC) systems in different regions, a clustering method for classifying regions based on factors of the reliability of AC systems is proposed. This study establishes a comprehensive evaluation model of regional clustering on the basis of analysis and investigation about the regional differences of natural environmental factors and user habit factors that influence the reliability of AC systems. A judging criterion of refrigeration and heating of air conditioner is set to accurately quantify seven clustering indicators. Ward method is used to calculate weight coefficients of different distance. Weighted Ward clustering algorithm (WWCA) is used for clustering regions from the perspectives of natural environmental factors and user habit factors, respectively. Two kinds of clustering results are integrated together to obtain the final results by secondary clustering analysis. Finally, the regional clustering of 31 provincial administrative areas in mainland China is presented to verify the applicability and validity of the method proposed in this study. The results of this study might establish the foundation for accurately predicting the use reliability of AC systems in different regions. It also provides well reference value for the similar study of refrigerators, washing machines, water heaters and solar street lamps, etc.
