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Modelo de planejamento de manutenção para caminhões de cargas frigorificadasPelegrini, Graciela Aparecida January 2013 (has links)
Atualmente a comercialização de produtos refrigerados, principalmente no Brasil, se dá graças ao transporte rodoviário frigorificado. Uma falha nesses veículos pode ser crucial para a perda de toneladas de alimentos. Entretanto, como este é o elo da cadeia de frios com menor índice de contaminação, muito pouco se fala sobre ele. Porém, trata-se de um item complexo, pois além de atingir o produto final, com alto valor agregado no processamento, o próximo elo é o cliente, que, muitas vezes, sem saber, pode acabar consumindo um produto degradado, em função de um transporte inadequado. Este trabalho foi elaborado visando contribuir com o setor de transporte de produtos perecíveis, melhorando a qualidade da manutenção dos veículos transportadores. Para garantir essa contribuição, este trabalho propôs desenvolver um modelo de gestão de manutenção para conjunto caminhão trator, carreta baú frigorificado e equipamento de refrigeração, baseado em técnicas atuais de manutenção, conciliadas à prática de manutenção existente em empresas de transportes e em normativas para transporte de produtos alimentícios frigorificados, aplicável a empresas transportadoras de cargas frigorificadas do Brasil e do mundo, sujeito a ajustes. Para isso foram realizadas pesquisas bibliográficas acerca das técnicas de manutenção MTP – Manutenção Produtiva Total, MCC – Manutenção Centrada em Confiabilidade e FMEA – Análise de Modo e Efeito de Falha, bem como normas nacionais e internacionais referentes à segurança alimentar e princípios do APPCC – Sistema de Análise de Perigos e Pontos Críticos de Controle. Após a revisão bibliográfica, extraíram-se as características de interesse de cada método e exigências das normas conciliadas à prática das empresas e desenvolvou-se um modelo de planejamento de manutenção. Posteriormente, o modelo foi aplicado em uma empresa frotista da região Oeste de Santa Catarina. A avaliação do método se deu por meio do comparativo entre o número de intervenções do planejamento antigo de manutenção da empresa e o planejamento proposto após a aplicação do modelo. Acredita-se que o modelo proposto é um modelo ideal para a empresa sob estudo, pois coletou estratégias para cumprir normativas de segurança alimentar e está ao alcance das empresas de transportes frigorificados. Por fim, como sugestão de trabalhos futuros do ponto de vista teórico, acredita-se que o trabalho possa servir de revisão bibliográfica acerca do assunto. Cabe ainda uma análise, a longo prazo, para avaliar a viabilidade econômica do modelo e realizar um comparativo de falhas. Do ponto de vista prático, acredita-se que o modelo de planejamento de manutenção possa ser informatizado e tornar-se uma exigência das normativas de transporte de alimentos. / Currently, the trade of refrigerated products mainly in Brazil, happens due to the refrigerated road transport. A flaw in these vehicles can be critical to the loss of tons of food. However, as this is the link of the of cold chain with the lowest contamination, very little is said about it. It is a complex point because besides, reaching the end product with high added to the value processing, the next link is the customer, who may often unknowingly end up consuming an indelible product due to an inadequate transportation. This study aimed at contributing to the transportation sector of perishable products, improving the quality of maintenance of transport vehicles. To ensure this contribution, this paper proposed to develop a model of maintenance management to the set tractor truck, cart bag and refrigerated cooling equipment, based on current maintenance techniques, reconciled to the practice of maintenance existent transportation companies and norms of transport in accordance of refrigerated food products, applicable to any enterprise refrigerated cargo carrier in Brazil and the world. Review of the current literature was carried out on maintenance techniques such as TPM, FMEA and MCC, as well as national and international norms related to food safety and HACCP principles. The qualities of each method and requirements of the standards norms were linked to industry practice and a model of maintenance planning. Was developed then, the model was applied in a transportation company in the west of Santa Catarina. The analytical method was through the comparison between the number of the old planning enterprise interventions and the planning proposed. The results that the proposed model is a complete model, since the strategies collected meet food safety norms and is feasible or refrigerated transport companies. Finally, as a suggestion for future research the in a theoretical perspective the present study can serve as a literature review on the subject. From a practical perspective the maintenance planning proposed can be computerized and become a referred norm for food transportation.
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Modelo de planejamento de manutenção para caminhões de cargas frigorificadasPelegrini, Graciela Aparecida January 2013 (has links)
Atualmente a comercialização de produtos refrigerados, principalmente no Brasil, se dá graças ao transporte rodoviário frigorificado. Uma falha nesses veículos pode ser crucial para a perda de toneladas de alimentos. Entretanto, como este é o elo da cadeia de frios com menor índice de contaminação, muito pouco se fala sobre ele. Porém, trata-se de um item complexo, pois além de atingir o produto final, com alto valor agregado no processamento, o próximo elo é o cliente, que, muitas vezes, sem saber, pode acabar consumindo um produto degradado, em função de um transporte inadequado. Este trabalho foi elaborado visando contribuir com o setor de transporte de produtos perecíveis, melhorando a qualidade da manutenção dos veículos transportadores. Para garantir essa contribuição, este trabalho propôs desenvolver um modelo de gestão de manutenção para conjunto caminhão trator, carreta baú frigorificado e equipamento de refrigeração, baseado em técnicas atuais de manutenção, conciliadas à prática de manutenção existente em empresas de transportes e em normativas para transporte de produtos alimentícios frigorificados, aplicável a empresas transportadoras de cargas frigorificadas do Brasil e do mundo, sujeito a ajustes. Para isso foram realizadas pesquisas bibliográficas acerca das técnicas de manutenção MTP – Manutenção Produtiva Total, MCC – Manutenção Centrada em Confiabilidade e FMEA – Análise de Modo e Efeito de Falha, bem como normas nacionais e internacionais referentes à segurança alimentar e princípios do APPCC – Sistema de Análise de Perigos e Pontos Críticos de Controle. Após a revisão bibliográfica, extraíram-se as características de interesse de cada método e exigências das normas conciliadas à prática das empresas e desenvolvou-se um modelo de planejamento de manutenção. Posteriormente, o modelo foi aplicado em uma empresa frotista da região Oeste de Santa Catarina. A avaliação do método se deu por meio do comparativo entre o número de intervenções do planejamento antigo de manutenção da empresa e o planejamento proposto após a aplicação do modelo. Acredita-se que o modelo proposto é um modelo ideal para a empresa sob estudo, pois coletou estratégias para cumprir normativas de segurança alimentar e está ao alcance das empresas de transportes frigorificados. Por fim, como sugestão de trabalhos futuros do ponto de vista teórico, acredita-se que o trabalho possa servir de revisão bibliográfica acerca do assunto. Cabe ainda uma análise, a longo prazo, para avaliar a viabilidade econômica do modelo e realizar um comparativo de falhas. Do ponto de vista prático, acredita-se que o modelo de planejamento de manutenção possa ser informatizado e tornar-se uma exigência das normativas de transporte de alimentos. / Currently, the trade of refrigerated products mainly in Brazil, happens due to the refrigerated road transport. A flaw in these vehicles can be critical to the loss of tons of food. However, as this is the link of the of cold chain with the lowest contamination, very little is said about it. It is a complex point because besides, reaching the end product with high added to the value processing, the next link is the customer, who may often unknowingly end up consuming an indelible product due to an inadequate transportation. This study aimed at contributing to the transportation sector of perishable products, improving the quality of maintenance of transport vehicles. To ensure this contribution, this paper proposed to develop a model of maintenance management to the set tractor truck, cart bag and refrigerated cooling equipment, based on current maintenance techniques, reconciled to the practice of maintenance existent transportation companies and norms of transport in accordance of refrigerated food products, applicable to any enterprise refrigerated cargo carrier in Brazil and the world. Review of the current literature was carried out on maintenance techniques such as TPM, FMEA and MCC, as well as national and international norms related to food safety and HACCP principles. The qualities of each method and requirements of the standards norms were linked to industry practice and a model of maintenance planning. Was developed then, the model was applied in a transportation company in the west of Santa Catarina. The analytical method was through the comparison between the number of the old planning enterprise interventions and the planning proposed. The results that the proposed model is a complete model, since the strategies collected meet food safety norms and is feasible or refrigerated transport companies. Finally, as a suggestion for future research the in a theoretical perspective the present study can serve as a literature review on the subject. From a practical perspective the maintenance planning proposed can be computerized and become a referred norm for food transportation.
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Heat transfer coefficient of a snow bagDa Veiga, Willem Richter 10 September 2014 (has links)
M.Ing. (Mechanical Engineering) / In snow shooting, pressurised liquid carbon dioxide is injected via a lance into a permeable snow bag mounted near the ceiling of an insulated transport container. The decrease in pressure causes the liquid carbon dioxide to convert to "snow" and vapour inside the snow bag. The snow bag acts as a phase separator, allowing the sublimated snow to cool down the products inside a container. In this thesis the heat transfer coefficients of such a snow bag were determined experimentally and theoretically. It was found, that on average the measured heat transfer coefficient was 31% lower than the theoretical prediction. The theoretical model was used to correlate the experimental heat transfer coefficient as function of snow height. With this correlation it was possible to predict the time of the snow life to within 24%.
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Modelo de planejamento de manutenção para caminhões de cargas frigorificadasPelegrini, Graciela Aparecida January 2013 (has links)
Atualmente a comercialização de produtos refrigerados, principalmente no Brasil, se dá graças ao transporte rodoviário frigorificado. Uma falha nesses veículos pode ser crucial para a perda de toneladas de alimentos. Entretanto, como este é o elo da cadeia de frios com menor índice de contaminação, muito pouco se fala sobre ele. Porém, trata-se de um item complexo, pois além de atingir o produto final, com alto valor agregado no processamento, o próximo elo é o cliente, que, muitas vezes, sem saber, pode acabar consumindo um produto degradado, em função de um transporte inadequado. Este trabalho foi elaborado visando contribuir com o setor de transporte de produtos perecíveis, melhorando a qualidade da manutenção dos veículos transportadores. Para garantir essa contribuição, este trabalho propôs desenvolver um modelo de gestão de manutenção para conjunto caminhão trator, carreta baú frigorificado e equipamento de refrigeração, baseado em técnicas atuais de manutenção, conciliadas à prática de manutenção existente em empresas de transportes e em normativas para transporte de produtos alimentícios frigorificados, aplicável a empresas transportadoras de cargas frigorificadas do Brasil e do mundo, sujeito a ajustes. Para isso foram realizadas pesquisas bibliográficas acerca das técnicas de manutenção MTP – Manutenção Produtiva Total, MCC – Manutenção Centrada em Confiabilidade e FMEA – Análise de Modo e Efeito de Falha, bem como normas nacionais e internacionais referentes à segurança alimentar e princípios do APPCC – Sistema de Análise de Perigos e Pontos Críticos de Controle. Após a revisão bibliográfica, extraíram-se as características de interesse de cada método e exigências das normas conciliadas à prática das empresas e desenvolvou-se um modelo de planejamento de manutenção. Posteriormente, o modelo foi aplicado em uma empresa frotista da região Oeste de Santa Catarina. A avaliação do método se deu por meio do comparativo entre o número de intervenções do planejamento antigo de manutenção da empresa e o planejamento proposto após a aplicação do modelo. Acredita-se que o modelo proposto é um modelo ideal para a empresa sob estudo, pois coletou estratégias para cumprir normativas de segurança alimentar e está ao alcance das empresas de transportes frigorificados. Por fim, como sugestão de trabalhos futuros do ponto de vista teórico, acredita-se que o trabalho possa servir de revisão bibliográfica acerca do assunto. Cabe ainda uma análise, a longo prazo, para avaliar a viabilidade econômica do modelo e realizar um comparativo de falhas. Do ponto de vista prático, acredita-se que o modelo de planejamento de manutenção possa ser informatizado e tornar-se uma exigência das normativas de transporte de alimentos. / Currently, the trade of refrigerated products mainly in Brazil, happens due to the refrigerated road transport. A flaw in these vehicles can be critical to the loss of tons of food. However, as this is the link of the of cold chain with the lowest contamination, very little is said about it. It is a complex point because besides, reaching the end product with high added to the value processing, the next link is the customer, who may often unknowingly end up consuming an indelible product due to an inadequate transportation. This study aimed at contributing to the transportation sector of perishable products, improving the quality of maintenance of transport vehicles. To ensure this contribution, this paper proposed to develop a model of maintenance management to the set tractor truck, cart bag and refrigerated cooling equipment, based on current maintenance techniques, reconciled to the practice of maintenance existent transportation companies and norms of transport in accordance of refrigerated food products, applicable to any enterprise refrigerated cargo carrier in Brazil and the world. Review of the current literature was carried out on maintenance techniques such as TPM, FMEA and MCC, as well as national and international norms related to food safety and HACCP principles. The qualities of each method and requirements of the standards norms were linked to industry practice and a model of maintenance planning. Was developed then, the model was applied in a transportation company in the west of Santa Catarina. The analytical method was through the comparison between the number of the old planning enterprise interventions and the planning proposed. The results that the proposed model is a complete model, since the strategies collected meet food safety norms and is feasible or refrigerated transport companies. Finally, as a suggestion for future research the in a theoretical perspective the present study can serve as a literature review on the subject. From a practical perspective the maintenance planning proposed can be computerized and become a referred norm for food transportation.
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Proposta de estratégia de controle de temperatura baseada em pré-resfriamento de produtos agrícolas perecíveis no transporte refrigerado rodoviário. / Proposal of a temperature control strategy based on pre-cooling of perishable agricultural products in regrigerated road transport.Kawano, Bruno Rogora 17 December 2018 (has links)
O desperdício de alimentos desde sua produção até o consumo, encontra-se, atualmente, no patamar de um terço de tudo o que é produzido no mundo. Durante a etapa de transporte, principalmente de alimentos com alta perecibilidade, tais como frutas e hortaliças, ocorrem perdas consideráveis devido à não utilização de tecnologia adequada de conservação e sua utilização é restrita devido ao seu alto custo. Durante o transporte refrigerado rodoviário de produtos agrícolas perecíveis, a carga transportada é suscetível à diversas aberturas de porta do caminhão refrigerado para a realização das entregas ao longo do percurso. Quando isso ocorre uma carga térmica de massa de ar entra no ambiente refrigerado elevando a temperatura neste momento, causando prejuízos em relação à qualidade do alimento transportado. Desta forma, é proposto neste trabalho uma etapa de pré-resfriamento em momento anterior à abertura das portas do caminhão refrigerado, a fim de se manter a temperatura dentro da faixa ideal de conservação. Para isso utilizou-se a estratégia do Controle PID na redução da temperatura antes da abertura de portas e após estas serem fechadas. Foi obtido um modelo em que foram simuladas aberturas de portas de um caminhão refrigerado utilizando técnicas de controle com o objetivo de manter a temperatura do ar do ambiente refrigerado dentro da faixa ideal. Os resultados obtidos indicam o potencial da utilização do controle de sistemas aliado à estratégia do pré-resfriamento na manutenção da temperatura auxiliando na preservação dos atributos de qualidade de alimentos transportados. Além disso, avalia-se que este modelo possa ser aplicado ao transporte refrigerado de outros alimentos. / Food waste, from its production up to its consumption, currently accounts for one-third of all the food produced in the world. During the transport stage, especially of highly perishable foods, such as fruit and vegetables, considerable losses occur due to not using adequate preservation technology; its use is limited owing to its high cost. Over the refrigerated road transport of perishable agricultural products, the load transported is susceptible to different door openings of the refrigerated truck for the deliveries along the route. When this occurs, an air mass thermal load enters the refrigerated environment elevating the temperature, causing damages to the quality of the food transported. Hence, this work proposes a pre-cooling stage at the moment prior to opening the doors of the refrigerated truck, so as to keep the temperature within the ideal preservation range. For this, PID Controller was employed for reducing the temperature before doors are opened and after they are closed. A model was obtained, whereby the door openings of a refrigerated truck were simulated using control techniques aiming to maintain the temperature of the refrigerated environment air within the ideal range. The results indicate the potential of using the system control combined with the pre-cooling strategy for keeping the temperature, aiding to preserve the quality attributes of the food transported. Besides, this model is believed to be able to be applied to the refrigerated transport of other foods.
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An analysis of temperature breaks in the summer fruit export cold chain from pack house to vesselHaasbroek, Laura Marchand 12 1900 (has links)
Thesis (MComm)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: There is great concern in the fruit industry that too much fruit and money is lost each year
due to breaks occurring in the export cold chain of fresh fruit. Therefore, the CSIR (Council
for Scientific and Industrial Research) and Stellenbosch University were approached to do
research on this problem. This particular study focuses on the cold chains of table grapes,
summer pears and plums as these fruit are especially sensitive to temperature.
Observations were made on fruit farms, in pack houses, in cold stores as well as in the Port
of Cape Town. From these observations it was clear that protocols are not always followed
and fruit quality is sometimes neglected because of pressure to speed up the exporting
process. In order to analyse the export cold chains of these fruit types, temperature trials
were conducted and temperature data received from exporting companies was analysed.
The data was analysed from the cold store up to the point where the vessel sailed out of the
Port of Cape Town. From the analysis it became clear that too many cold chain breaks occur
during fruit exports from South Africa, especially during the loading of containers at cold
stores.
As a final output to the study, a good cold chain practice guide for the export of table grapes
was developed with the aim of assisting the fruit industry in minimizing these cold chain
breaks. The guide was developed with simplicity to ensure easy understanding under all
role-players in the industry.
This study was a small step in the right direction, but it should be highlighted that the
complexity of the problems in the fruit cold chains are substantial and further research will
have to be done in order to eliminate the occurrence of these cold chain breaks.
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Sänkt temperatur i kylkedjan : Konsekvenser för transportbranschen / Decreased temperature in the cold chain : Consequences for the transportBjörkgren, Anton, Eriksson Sjöqvist, Edvin January 2017 (has links)
Idag transporteras kylda livsmedel, i Sverige, inom ett temperaturintervall på +2 °C - +8 °C. I vilken temperatur som animaliska livsmedel ska hanteras i regleras i lagstiftningen och varierar mellan +2 °C - +7 °C. Många kylskåp, både hos butik och konsument, är inställda på+8 °C. Till följd av detta är den stora majoriteten livsmedel, på förpackningen, markerade med en förvaringstemperatur på +8 °C. På senare år har diskussioner förts angående en sänkt temperatur i kylkedjan. Anledningen till detta är att överkomma matsvinnet. Forskning pekar på att ett livsmedels hållbarhet är starkt beroende av dess förvaringstemperatur. Hastigheten på mikrobiell tillväxt sjunker nämligen med lägre temperaturer. År 2020 träder en ny förordning om fluorerade växthusgaser (fgasförordningen)i kraft som förbjuder installation och påfyllning av kommersiell utrustning innehållande köldmedier med högre Global Warming Potential-faktor än 2500. Detta innebär att butiksledet i stor utsträckning kommer tvingas byta ut sina äldre kylsystem. Med nya kylsystem kan en lägre temperatur garanteras. För att vara väl förberedda ställer sig transportbranschen frågan vilka konsekvenser en sänkttemperatur kan tänkas föra med sig i deras del av kedjan. Problematiken grundar sig i att en del livsmedel kan ta skada av temperaturer nära fryspunkten. För att skydda dessa livsmedelkan transportören använda sig av produktskydd på kylkänsliga livsmedel. En annan beprövad metod är att dela in livsmedlen i flera temperaturzoner. Arbetets teoretiska bidrag är att det sammanställer tidigare forskning på områden inom livsmedelsegenskaper vid nedkylning, multitemperatursystem och produktskydd samt semistrukturerade intervjuer med experter inom sina respektive områden. Vidare undersöksäven kylkedjans uppbyggnad och dess aktörer. Perspektivet i rapporten utgår från ett av de större transportföretagen inom tempererad logistik i Sverige. Arbetets praktiska bidrag är baserat på en fallstudie som tillsammans med det teoretiska bidraget ligger till grund för en redogörelse över tänkbara konsekvenser. Analysen visar på att en del livsmedel, för att inte komma till skada och riskera kassation, måste skyddas. Antingen genom flera temperaturzoner eller genom produktskydd. Bådaalternativen kommer med för- och nackdelar. Att addera flera temperaturzoner för med sig investeringar i form av mellanväggar och kylsystem samt komplicerar livsmedelshanteringen. Flera temperaturzoner kan emellertid säkra ett livsmedels kvalitet. För produktskydden existerar det inget returlogistiksystem och ett system kan bli mycket kostnadsdrivande att upprätthålla. Slutsatsen är att en kombination av de båda lösningarna är att föredra men att branschöverskridande samarbete krävs för att samtliga parter ska gynnas. / Chilled foodstuffs are today transported within a temperature interval of +2 °C - +8 °C in Sweden. The correct temperatures in which foodstuffs with animal origin should be handled in are regulated by law and diverges between +2 °C - +7 °C. Many refrigeration systems in grocery stores and consumer’s homes are set at +8 °C. The great majority of foodstuffs are, as a result of this, on the packaging marked with a storage temperature of +8 °C. To be well prepared, the transport industry ask themselves which consequences might occur in case of a reduced temperature in the cold chain. The main reason for this is to overcome food waste. Research shows that foodstuffs durability is highly dependent on its storage temperature. The rate in which microbial growth occur drops with falling temperatures. In2020 a new EU regulation enters in to force which regulates the use of refrigerants with higher Global Warming Potential factor than 2500. The grocery stores have to, as a result of this, replace many of their older refrigeration systems. Regulating lower temperatures won’t be an issue with new modern equipment. As a result of this they can guarantee lower temperatures on foodstuff. To be prepared for what might come, the transport industry wants to know what consequences a lower temperature might bring along in their part of the cold chain. The main issue is that some foodstuff might be harmed in temperatures close to the freezing point. The use of protective coatings could offer shelter for cold sensitive products. One other proven method is to allocate foodstuff in different temperature zones. This thesis theoretical contribution compiles earlier research in areas such as foodstuffs characteristics when refrigerated, multi temperature systems, protective coatings and semi structured interviews with experts within their fields. It further examines the cold chain and the stakeholders within it. The focus of the thesis is thru the perspective of one of the major transport companies within cold chain logistics in Sweden. The practical contribution is based on a case-study together with the theoretical contribution which states consequences that possibly can occur along the transport company’s part of the cold chain. The analysis shows that, to minimize the risk of cassation, some foodstuffs need protection. Either thru multiple temperature zones or with protective covers. Both alternatives comes with advantages and disadvantages. To add temperature zones are associated with investments in the form of separable walls and cooling systems together with an increase in logistic complexity. Multi temperature systems can however secure the quality in a foodstuffs quality. The issue with protective covers is that there’s no return logistics system in place and such a system can be very expensive to uphold. The covers do however offer protection from outer temperature influence. The conclusions states that a combination of both solutions might be suitable. To accomplish this however requires collaboration over company and industry borders if all stakeholders are to be beneficial.
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Caractérisation expérimentale et modélisation des transferts thermique/hydrique et de la croissance microbienne au cours du transport frigorifique de carcasses de porc / Experimental caracterisation and modeling of heat/mass transfer and microbial growth during refrigerated transport of pork carcassesMerai, Mouna 08 November 2018 (has links)
L’objectif de ce travail est de développer une démarche permettant de prédire l’évolution de la charge microbienne à la surface de carcasses de porc lors d’un transport frigorifique selon les conditions opératoires (température et humidité de l’air de soufflage) et des conditions initiales (profil de température en sortie de chambre froide d’abattoir). La croissance microbienne dépendant notamment de la température et de l’activité de l’eau, il est nécessaire d’étudier les transferts de chaleur et de matière de type diffusif au sein des carcasses et de type convectif autour des carcasses. Ces derniers dépendent de la circulation d’air dans le véhicule frigorifique lorsqu’il est chargé de centaines de demi-carcasses ce qui rend la géométrie particulièrement complexe.De ce fait, ce travail fait appel à diverses disciplines : mécanique des fluides, transferts thermiques et microbiologie prévisionnelle. Le couplage de ces trois disciplines permet d’apporter des réponses scientifiques quant à la qualité sanitaire des carcasses de porc.En travaillant sur un dispositif expérimental reproduisant une semi-remorque chargée de carcasses de porc à l’échelle réduite, les écoulements d’air ont pu être caractérisés par vélocimétrie laser Doppler 2D dans deux configurations de distribution d’air (avec et sans conduits). De plus, les coefficients de transfert convectifs locaux ont pu être estimés à la surface de différentes parties des carcasses de porc et à différentes positions dans la semi-remorque à l’échelle réduite. Un schéma simplifié des écoulements d’air a été établi, il permet de localiser les « zones à risque » dans la semi-remorque chargée (faible circulation d’air et faible coefficients de transfert convectif).En se basant sur les résultats de l’étude expérimentale à l’échelle laboratoire et sur ceux récoltés au cours de vrais transports frigorifiques, la variabilité des paramètres caractérisant l’air circulant autour des carcasses a pu être estimée. Ces informations ont servi de conditions aux limites d’un modèle de transfert de chaleur et de matière (eau) au sein de la partie la plus sensible au niveau microbiologique: le jambon. Ce modèle 3D, résolu par la méthode des éléments finis, permet de prédire l’évolution de la température, de la teneur en eau et de la charge microbienne (Pseudomonas) à la surface de la partie maigre du jambon pour différents scénarios de transport frigorifique. Les résultats ont montré que si le transport commence alors que le cœur des carcasses est encore tiède (15°C au lieu de 7°C selon la réglementation actuelle) la croissance des microorganismes à la surface des carcasses de porc n’est globalement pas plus importante entre l’abattage et l’arrivée sur le site de découpe.Enfin, une étude de terrain a permis de valider les données obtenues à l’échelle du laboratoire et de réaliser une étude énergétique. Il apparait que quelle que soit le pourcentage de carcasses tièdes dans la semi-remorque, la capacité frigorifique du système de production de froid est généralement suffisante pour évacuer la chaleur des carcasses.Cette étude a permis de développer des méthodes de caractérisation des écoulements et des transferts dans une géométrie particulièrement complexe. Elle a montré l’intérêt de coupler des modèles de transfert et de microbiologie prévisionnelle. Les expérimentions à l’échelle laboratoire ont été construites en reproduisant au plus près les conditions réelles grâce à l’appui de spécialistes de la filière viande. Ainsi les carcasses modèles ont été réalisées dans des moules obtenus par impression 3D d’après des scanners X de vraies carcasses. Les résultats de cette étude sont directement utilisables par la profession et les pouvoirs publics pour l’adaptation de la réglementation des transports réfrigérés. La démarche développée pourra être adaptée pour des problèmes similaires dans des enceintes ventilées très encombrées. / The objective of this work is to develop an approach allowing to predict the evolution of the microbial load on the surface of pork carcasses during a refrigerated transport according to the operating conditions (temperature and humidity of the blowing air) and initial conditions (temperature profile at the outlet of the slaughterhouse cold room). Since microbial growth depends mainly on temperature and water activity, it is necessary to study heat and mass transfer the transfer within and around the carcasses. These phenomena depend on the circulation of air in the refrigerated vehicle loaded with hundreds of half-carcasses which makes the geometry particularly complex.Thus, this work involves various disciplines: fluid mechanics, heat transfer and predictive microbiology. The coupling of these three disciplines makes it possible to provide scientific answers as to the sanitary quality of the pork carcasses.By conducting experiments on a semitrailer loaded with pork carcasses on a reduced scale, the air flows could be characterized by 2D Doppler laser velocimetry in two air distribution configurations (with and without air ducts). In addition, local convective heat transfer coefficients could be estimated at the surface of different parts of pork carcasses and at different positions in the reduced-scale trailer. A simplified model of the airflow has been established, that makes it possible to identify the "risk zones" in the loaded semi-trailer (low air circulation and low convective transfer coefficients).Based on the results of the experimental laboratory scale study and those collected during actual refrigerated transport, the variability of the parameters characterizing the air circulating around the carcasses could be estimated. This information served as boundary conditions for a model of heat and mass (water) transfer within the most sensitive part at the microbiological level: the ham. This 3D model, solved by the finite element method, makes it possible to predict the evolution of the temperature, the water content and the microbial load (Pseudomonas) on the surface of the lean part of the ham for different scenarios. The results showed that if the transport begins while the heart of the carcasses is still warm (15°C instead of 7°C according to current regulation) the growth of microorganisms on the surface of pork carcasses is generally not more between slaughter and arrival at the cutting site.Finally, a field study validated the data obtained at the laboratory scale and carried out an energy study. It appears that whatever the percentage of warm carcasses in the semi-trailer, the cooling capacity of the cooling system is generally sufficient to evacuate the heat of the carcasses.This study has made it possible to develop a method that characterizes airflow and heat transfer methods in a particularly complex geometry. It showed the interest of coupling transfer models and predictive microbiology models. Experiments at the laboratory scale were built by reproducing the real conditions as closely as possible thanks to the support of specialists in the meat sector. Thus the model carcasses were made in molds obtained by 3D printing from X-Ray scanners of real carcasses. The results of this study are directly usable by the profession and the public authorities for the adaptation of the refrigerated transport regulations. The approach developed may be adapted for similar problems in very congested ventilated enclosures.
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