WHAT IT DOES
The developed machines rapidly cool crop upon harvest thus increasing its shelf life by up to 3 times, they do so quicker and 70% more energy efficiently than any other machine of its kind. Moreover, they recover significant clean water from the cooled crops.
Several published journals and articles state that food and water scarcity are experienced in several parts of the world, and that the problem will get worse as populations increase and climates continue to change. I also watched a documentary saying that certain food-poor countries such as India actually produce more food than the nation’s demand, however because up to 50% of it rots before reaching its consumers, over 140 million people still go to sleep hungry. Moreover, standard vacuum-cooling machines are too energy intensive to be adopted in such areas and are hence often powered by dirty diesel-generators as an alternative.
HOW IT WORKS
After harvest, the crop is placed inside the vacuum cooling machine vessel. The process begins when the vacuum-pumps start extracting air out of the vessel until the pressure reaches 6 mbar. As pressure decreases, the boiling point of water also decreases. A small percentage of water evaporates off the produce using the crop’s latent heat, thus cooling the crop. Condensers are activated once the moisture in the vessel reaches a certain level to avoid any damage to the vacuum-pumps. The cycle duration is dependent on the product being cooled, but averages to 25 minutes. These machines are entirely customisable and made out of high-grade steel. They weigh from 3 tonnes upwards and, if well maintained, can incur a lifetime of over 30 years.
After having learnt about the existing technology and worked alongside a company (Inviro Choice Ltd) that manufactures them, I was able to think about improvements that could be made. I discussed all of my ideas with the company director, Sean Roche, who has over 10 years of experience in the cooling sector. The improvements that seemed most viable and effective were then tested out using small-scale laboratory equipment and prototypes. I designed all of the experiments and measured the data to quantitively evaluate their changes in performance. I ensured that the data was reliable and valid by conducting the tests numerous times and by incorporating variations in the inputs of each experiment. Where possible, we incorporated the design improvements in commercial-size existing vacuum-cooling machines. I gathered data for these machines before and after the developments were fitted/made and had my supervisor at the University of Exeter re-evaluate and re-validate the results. The Institution of Mechanical Engineers was so impressed by the project and its outcome that they had Sean and I present them at various events, including one at the Institution of Mechanical Engineers headquarters in London.