Multi-objective optimization of storage temperature of apple to minimise energy use

Low temperature storage is widely employed to increase the storage life of apples. However, the use of refrigeration accounts for up to 15% of the global use of electricity. Increasing the storage temperature by 1°C can significantly reduce the total cost of electricity during apple storage. In this study, a multi-objective optimization approach is used to suggest new storage temperature of apple, taking into consideration the cost of electricity and the quality of the apple at the end of storage. Energy use was calculated using vapor pressure compression cycle models. Apple firmness was selected as the most important quality indicator for apple grading. The quality of the apple at the end of storage was converted to money value in €, based on the current grading system of apples in Belgium. Firmness was calculated using the firmness model developed by Gwanpua et al. (2012).The objective was to optimize storage temperature by minimizing the electricity usage, while minimizing quality losses (i.e. by maximizing the money value of the apple at the end of storage). This was done for different storage duration, and also for cool rooms with different storage capacity. New storage temperatures of apple, that will reduce the use of energy, were suggested

A quality, energy and environmental assessment tool for the European cold chain

According to 5th Informatory Note on Refrigeration and Food published by the International Institute of Refrigeration, 20% of the global losses in perishable products was due to lack of refrigeration. It is expected that increased use of refrigeration to reduce these losses will help meet the increasing food demands of the growing world population. However, the use of refrigeration already accounts for about 15% of world’s electricity usage. In addition, the use of refrigeration significantly contributes to global warming via emission of CO2. In this paper, a software tool was developed to assess food quality and safety evolution, energy usage and CO2 emission of different refrigeration technologies along the European cold chain. A reference product was chosen for the main different food categories in the European cold chain. Software code to predict the products temperature using the room temperature as input, based on validated heat and mass transfer models, were written in Matlab (The Mathworks Inc., Natick, USA). Also, based on validated kinetic models for the different quality indicators of the reference products, a software code was written to calculate the quality and safety evolutions of the food product, using the predicted product temperature as input. Finally, software code to calculate the energy usage and Total Equivalent Warming Impact (TEWI) value of different refrigeration technologies was also written in Matlab. All three software codes were integrated, and a graphical user interface was developed. Using the graphical user interface, a user can tailor a cold chain scenario by adding different cold chain blocks. Each cold chain block has properties that can be modified. The tool can be used to compare different cold chains with respect to quality, safety, energy usage, and environmental impact

Towards sustainability in cold chains: Development of a quality, energy and environmental assessment tool (QEEAT)

Quantification of the impact of refrigeration technologies in terms of the quality of refrigerated food, energy usage, and environmental impact is essential to assess cold chain sustainability. In this paper, we present a software tool QEEAT (Quality, Energy and Environmental Assessment Tool) for evaluating refrigeration technologies. As a starting point, a reference product was chosen for the different main food categories in the European cold chain. Software code to predict the products temperature, based on validated heat and mass transfer models, were written in Matlab (The Mathworks Inc., Natick, USA). Also, based on validated kinetic models for the different quality indicators of the reference products, (including fruit, meat, fish, vegetables and dairy products) a software code was written to calculate the quality and safety evolutions of the food product, using the predicted product temperature as input. Finally, software code to calculate the energy usage and Total Equivalent Warming Impact (TEWI) value of different refrigeration technologies was also written in Matlab. All three software codes were integrated, and a graphical user interface was developed. Using the QEEAT, a user can tailor a cold chain scenario by adding cold chain blocks (different steps of a cold chain) and simulating the quality evolution, energy use and emission throughout the chain. Also, the user can modify properties of a cold chain block, by selecting different technologies, or changing set point values. Defaults are provided for input values, and are based on the current practice, and obtained by extensive literature studies and consultation with different experts of the cold chain. Furthermore, the user can build and simulate several chains simultaneously, allowing him/her to compare different chains with respect to quality, energy and emission