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Abstract(s)
A APP (Advanced Products Portugal) é uma empresa portuguesa com mais de 15 anos de experiência, focada na resolução de pontos críticos da cadeia térmica nos setores da Saúde, Farmacêutico e Alimentar. O conhecimento da cadeia térmica e o desenvolvimento de sistemas isotérmicos que permitam conservar a temperatura de produtos termossensíveis durante o transporte é, atualmente, o principal foco da empresa. De forma a responder às necessidades da APP, desenvolveu-se uma ferramenta de previsão de Temperaturas que permite avaliar o comportamento térmico no interior de um sistema isotérmico em função das suas características e do produto a ser transportado. O desenvolvimento da ferramenta de previsão de temperaturas teve como base a solução analítica da 2º Lei de Fourier para transferência de calor em estado não estacionário, e considerando as diversas variáveis que constituem um sistema isotérmico. Tem como objetivo analisar e simular o comportamento do interior da embalagem com a variação da temperatura externa. Recorrendo ao uso da ferramenta de previsão, desenvolvida em Matlab, é possível analisar e verificar quais são as variáveis que influenciam a temperatura do produto. A ferramenta matemática foi validada experimentalmente, através dos valores de temperatura obtidos na posição central e lateral no interior do sistema, recorrendo ao uso de uma embalagem cúbica com dimensão lateral de 0,25 m, preenchida com água, de forma a simular o produto. Recorrendo a um desenho fatorial a dois níveis foi possível avaliar os parâmetros que mais influenciam a temperatura do produto, comparando 5 variáveis selecionadas: dimensão da embalagem isotérmica cúbica, temperatura ambiente (𝑻∞), condutividade térmica da embalagem (k), espessura (Δ𝒙) e temperatura inicial do produto (𝑻𝒊), relativas aos materiais constituintes da embalagem, e condições externas a que o sistema isotérmico está sujeito (convecção forçada ou natural). Como resposta foi avaliado o tempo até que a temperatura lateral e central atinja o valor limite estabelecido.
Concluiu-se que as variáveis que mais influenciam a temperatura do produto são a dimensão, 𝑻∞, k, e Δ𝒙, assim como efeitos combinados da dimensão com 𝑻∞, Δ𝒙 ou k, e de k com 𝑻∞. A temperatura inicial do produto, 𝑻𝒊, não influencia o comportamento do sistema isotérmico. A constituição da embalagem e o sistema isotérmico estar perante convecção forçada ou natural à superfície vai influenciar também o desempenho do sistema isotérmico na conservação da temperatura do produto. A ferramenta de previsão de temperatura foi desenvolvida para situações limitadas e não consegue responder a todas as necessidades da APP e dos seus clientes. No entanto, é uma ferramenta útil para estimar como os sistemas isotérmicos respondem a um conjunto de variáveis. No futuro dever-se-á melhorar a ferramenta de previsão de temperaturas considerando novos modelos que permitam aumentar a exatidão dos valores de temperatura.
The APP (Advanced Products Portugal) is a Portuguese company with more than 15 years of experience, focused on the resolution of critical points of the thermal chain, specifically in the health, pharma and food sectors. The main focus of the company is the development of isothermal systems to maintain the temperature of thermosensitive products during their transportation. To answer the needs of APP, a temperature simulation tool was developed to evaluate the internal thermal behavior of an isothermal system, depending on its characteristics and the product to be transported. The tool development was based on the analytical solution of the 2nd Fourier law for heat transfer under unsteady state conditions, considering all the variables that form an isothermal system. The purpose is to analyze and simulate the package thermal behavior according to the external temperature change. Taking profit of the predictive tool, developed in Matlab, it is possible to analyze and verify which variables influence most the product’s temperature. The mathematical tool was validated experimentally, obtaining values at the central and lateral positions inside the system, using a cubic package with a lateral dimension of 0.25m, filled with water as a model. Using a full factorial design at two levels, among 5 pre-selected variables: dimension of the cubic isothermal package, environment temperature (𝑻∞), package thermal conductivity (k) and thickness (Δ𝒙), and initial temperature of the product (Ti), it was possible to conclude on the parameters that influence the most the product’s temperature. The variables are related to the package properties and the isothermal system external conditions. As response, the required time to reach the limit allowed values, for the lateral or central product temperatures, was evaluated. The variables that have the higher influence on the response are the: dimension, 𝑻∞, k, and Δ𝒙, as well as combined effects of the dimension with 𝑻∞, Δ𝒙 or k, and k with 𝑻∞. The product initial temperature, Ti, does not influence the isothermal system behaviour. The type of heat transfer (natural or forced convection) at the isothermal system surface also influences its performance in keeping the product temperature within limited values. The predictive tool was designed for limited situations and is not able to answer all the APP and its clients needs. However, it is an useful tool to estimate and predict how the isothermal systems respond to influencing variables. Moreover, in future developments it is expected to be improved considering new models that can enhance the accuracy of the predicted results. These new developments will require the use of numerical solutions.
The APP (Advanced Products Portugal) is a Portuguese company with more than 15 years of experience, focused on the resolution of critical points of the thermal chain, specifically in the health, pharma and food sectors. The main focus of the company is the development of isothermal systems to maintain the temperature of thermosensitive products during their transportation. To answer the needs of APP, a temperature simulation tool was developed to evaluate the internal thermal behavior of an isothermal system, depending on its characteristics and the product to be transported. The tool development was based on the analytical solution of the 2nd Fourier law for heat transfer under unsteady state conditions, considering all the variables that form an isothermal system. The purpose is to analyze and simulate the package thermal behavior according to the external temperature change. Taking profit of the predictive tool, developed in Matlab, it is possible to analyze and verify which variables influence most the product’s temperature. The mathematical tool was validated experimentally, obtaining values at the central and lateral positions inside the system, using a cubic package with a lateral dimension of 0.25m, filled with water as a model. Using a full factorial design at two levels, among 5 pre-selected variables: dimension of the cubic isothermal package, environment temperature (𝑻∞), package thermal conductivity (k) and thickness (Δ𝒙), and initial temperature of the product (Ti), it was possible to conclude on the parameters that influence the most the product’s temperature. The variables are related to the package properties and the isothermal system external conditions. As response, the required time to reach the limit allowed values, for the lateral or central product temperatures, was evaluated. The variables that have the higher influence on the response are the: dimension, 𝑻∞, k, and Δ𝒙, as well as combined effects of the dimension with 𝑻∞, Δ𝒙 or k, and k with 𝑻∞. The product initial temperature, Ti, does not influence the isothermal system behaviour. The type of heat transfer (natural or forced convection) at the isothermal system surface also influences its performance in keeping the product temperature within limited values. The predictive tool was designed for limited situations and is not able to answer all the APP and its clients needs. However, it is an useful tool to estimate and predict how the isothermal systems respond to influencing variables. Moreover, in future developments it is expected to be improved considering new models that can enhance the accuracy of the predicted results. These new developments will require the use of numerical solutions.
Description
Keywords
Sistema isotérmico Cadeia de distribuição Transferência de calor Ferramenta de previsão Isothermal systems Distribution chain Heat transfer Predictive tool