3. Frederick JonesFrederick Jones is credited with inventing a portable air-cooling unit for trucks carrying perishable items. He received the patent in 1940, according to a Wikipedia article on Jones. The refrigeration units were used during World War II to preserve blood, medicine and food to be used at army hospitals and on open battlefields.
Jones held 61 patents, most of which are for refrigeration equipment. The others are for portable X-ray machines, sound equipment and gasoline engines.