Modelling the climate in a transport container

Thesis (M.Sc. (Applied Mathematics))--North-West University, Potchefstroom Campus, 2005.

The transportation of agro-products is essential for all of us. The quality of food after transportation is very important - none of us will buy poor quality food. In September 2002, A&FI started the three year research project QUEST(Quality and Energy efficiency in the Storage and Transportation of Agro-materials), with the focus on the use of containers to transport products overseas. The aim of QUEST is to find ways to reduce energy consumption for climate conditioning during transportation of perishable goods, and to monitor the product quality in order to minimize product losses. To achieve these goals, predictive models that describe the climate in one box, in a layer consisting out of nine boxes, and in a stack (few layers on top of each other) should be developed. The transport containers used, have a cooling unit in the front and a sensor system measuring the temperature and humidity inside the container. The goods are stored in cardboard boxes that are stacked in piles on pallets. The climate inside the container can be controlled by the circulation of cooled air. The main goal of this project is to develop a two-dimensional model predicting the climate in one layer of boxes. The company A&FI already has a model for the whole container, and wants to plug my resulting model, for one layer of boxes, into their model. First I model a box and a slit (space between the boxes) separately. Subsequently I derive a network model for one layer consisting of nine boxes. The idea of the network is to replace the temperature distribution by the averaged temperature related to each box and slit. Such a method is strongly based on the description of heat transfer using the analogy with electrical circuits. My model makes it possible to determine the average temperatures at any moment of time, i.e. , predict the climate within a layer inside a transport container. My model brings A&FI another step closer in the process to have a global model for the whole container. I recommend further extension of our model to a stack of boxes (to three dimensions).

Masters