Conference Agenda

Meeting the increasing demand for cooling while reducing carbon emissions is critical for sustainable logistics in Norway’s fruit and vegetable supply chain. The Norwegian food market is dominated by three major retail chains, which manage their own distribution systems with the support of one main third-party import provider. Although parts of goods are transported by train, the majority relies on trucks, posing significant challenges for sustainability. Centralized storage systems coexist with local storage units for fruits and vegetables, leading to increased transport frequency and energy use. Transparency across supply chains is essential to optimize energy consumption, minimize food loss and waste, and lower CO₂ emissions. By improving cooling technologies, reform transport logistics, and integrating innovative sustainability practices, Norway’s food sector can address growing cooling demands while advancing toward reduced carbon footprints. This study explores opportunities to enhance the efficiency and environmental impact of cooling and transport systems in this context.

The ejector technology is one of the most promising solutions in vapour compression units, especially for natural refrigerant-based systems, i.e., the CO₂ refrigeration and mobile air-conditioning systems, due to the expansion work recovery, which extends the application of such systems. Nevertheless, the design of the two-phase ejector required complex capacity control, e.g., using several ejectors operated in single or parallel modes, a needle in the converging-diverging motive nozzle or the oscillator source. Therefore, the main aim of this paper is to evaluate experimentally the possible control of the two-phase ejector operation by implementing the thermoelectric sub-cooler. The experimental investigation was done using the test stand of the CO₂ ejector-based refrigeration system equipped with the prototype thermoelectric sub-cooler at different gas cooler outlet temperatures in the range from 25.0 °C to 45.0 °C determining different climate zones. The test campaign is defined to evaluate the potential of ejector capacity control providing the voltage of TEMs up to 10.0 V DC.

Traditionally, Cold TES (CTES) has been used in transport refrigeration in the form of eutectic plates mounted inside insulated boxes, especially for last-mile deliveries. Due to their flexibility, these boxes represent a valid option to increase the resilience of the cold chain under emergency situations, like floods, landslides, etc that are becoming more frequent.

To increase the overall sustainability of the entire solution, and to guarantee the accessibility to cheap and widespread refrigerants, this study presents and numerically evaluates the performance of an efficient cooling unit relying on an innovative TES configuration (eutectic tubes) and on natural refrigerant (propane), to replace a baseline cooling unit employing a synthetic refrigerant.

The numerical model is validated against experimental data measured on the baseline unit and demonstrates a +12.6% pulldown COP increase of the proposed system compared to baseline under standard test conditions. Considerations regarding propane charge are also included.

In the supply chain of fruits and vegetables, products are cooled down and stored in cold storage. However, they may be exposed to temperature fluctuations in the refrigeration system or when the cold product is summited to the warm ambient when the product is transported from one place to another. Water condensation can occur on the product surface. When the cold product is exposed to warm air, water condenses on the produce surface at temperatures below the dew point. Condensation on the product surface is an unfavorable condition for product quality. This promotes spore formation and the growth of microorganisms. This study aims to develop a model of heat and mass transfer in bulk fruits, including condensation. The model predicts air and product temperatures and water condensation within a container exposed to temperature fluctuations and was validated against experimental data. This model can potentially predict air and product temperature evolution and accumulation of water condensation.