O. Laguerre

Heat transfer by natural convection in domestic refrigerators

This paper analyses heat transfer by natural convection in domestic unventilated refrigerators. A literature review of natural convection in an empty cavity, between vertical plates and air, and between a cylinder and air, was conducted in order to gain an insight into the mechanism of heat transfer. A model is proposed in order to quantify heat exchange by convection, conduction and radiation in a typical refrigerator; the predicted mean air temperature and refrigerating capacity are close to the experimental values. Another numerically solved model was carried out in order to estimate the time required to cool warm food which is placed inside the refrigerator. Good agreement was obtained when calculated and experimental temperatures were compared.

Combining Quantitative Risk Assessment of Human Health, Food Waste, and Energy Consumption: The Next Step in the Development of the Food Cold Chain?: Combining Quantitative Risk Assessment of Human Health, Food Waste, and Energy Consumption

The preservation of perishable food via refrigeration in the supply chain is essential to extend shelf life and provide consumers with safe food. However, electricity consumed in refrigeration processes has an economical and an environmental impact. This study focuses on the cold chain of cooked ham, including transport, cold room in supermarket, display cabinet, transport by consumer, and domestic refrigerator, and aims to predict the risk for human health associated with Listeria monocytogenes, the amount of food wasted due to the growth of spoilage bacteria, and the electrical consumption to maintain product temperature through the cold chain. A set of eight intervention actions were tested to evaluate their impact on the three criteria. Results show that the modification of the thermostat of the domestic refrigerator has a high impact on food safety and food waste and a limited impact on the electrical consumption. Inversely, the modification of the airflow rate in the display cabinet has a high impact on electrical consumption and a limited impact on food safety and food waste. A cost-benefit analysis approach and two multicriteria decision analysis methods were used to rank the intervention actions. These three methodologies show that setting the thermostat of the domestic refrigerator to 4 °C presents the best compromise between the three criteria. The impact of decisionmaker preferences (criteria weight) and limitations of these three approaches are discussed. The approaches proposed by this study may be useful in decision making to evaluate global impact of intervention actions in issues involving conflicting outputs.