Cooling unit impact on energy and emissions of a refrigerated light truck

The dynamic numerical simulation of an urban multi-drop delivery mission of perishable goods inside a medium-size refrigerated truck is presented. Three different connections between the cooling unit's compressor and the vehicle engine are considered: a direct belt drive, the use of a dedicated alternator and the implementation of a battery to store energy from the engine and then feed the compressor. A dynamic numerical model of the whole system is built to simulate the real-time operation of both the refrigerating system and the vehicle engine during the delivery mission, providing a novel modelling approach accounting for the interaction between refrigeration needs and environmental impact. Simulation results show that the compressor speed control leads to a 26.0% increase of the mission COP and to an overall improvement of the cargo space internal air conditions. A 19.0% increase of the fuel consumption due to the presence of the cooling unit is assessed. However, the implementation of a battery mitigates the fuel consumption increase from 19.0% to 5.7% and leads to a significant reduction in pollutant emissions. The results of this study are relevant to assess the environmental impact of the refrigerated road transport sector in urban environment and to suggest possible improvements.