Rambutan Washer
This project was associated with my undergraduate senior design class. My team and I decided to pursue a company sponsored project in which we were challenged to create a completely new piece of technology. It was our task to develop an innovative machine that would automatically clean and disinfect a particular variety of tropical fruit, called Rambutan, to meet USDA import standards.
Background
Tropical fruit makes up a large percentage of the farmed goods in many Central and South American countries. Not only is tropical fruit a delicious treat for the locals, but it is also a very popular export to the United States and even other places in Europe. While there are many logistical challenges in the tropical fruit business, the two biggest hurdles that constantly need to be overcome are cleanliness and shelf life. The USDA has very strict import standards when it comes to tropical fruit coming from third world countries which puts extra stress on the workers cleaning the fruit at packing facilities. Additionally, particular varieties of tropical fruit have a very limited shelf life also putting stress on these farms to export their goods fast so the product can be on the shelf in the markets before going bad. These two issues are very much interdependent, the strict USDA regulations make the cleaning and packing process longer which reduces the amount of time the fruit has in the store before going bad. Alternatively if corners are cut during the cleaning process to try and gain extra time on the shelf at the store these farms risk failing a border inspection at which point the entire shipment is lost. Needless to say these are very challenging issues.
Problem Statement
Fungus and scale/scama bugs are the two most common reasons for rambutan failing USDA inspections. The fungus grows on the outside of the fruit while on the farm and the scale bugs nest themselves at the base of the fruit hairs. Due to the strict USDA import standards and lack of both cutting edge technology and capital at third world farms, the entire fruit cleaning process is done manually by workers with toothpicks and magnifying glasses. Our task was to design a piece of equipment or machine that would reliably clean/disinfect Rambutan to USDA import standards at a rate substantially faster than the manual labor. Our device needed to be portable for easy transportation, self contained not requiring external support to function (electricity, internet, fancy software), and relatively inexpensive so these farms could afford to purchase and operate them.
Solution
By the end of the semester my team had a full scale working prototype of a completely mechanical machine to remove fungus and scale bugs from Rambutan. Our machine utilized a completely custom, patent pending, helical waterjet coil for 360 degree fruit coverage. These waterjets were designed to blast the fruit from all angles at a pressure high enough to eliminate all debris but low enough to insure no damage to the fruit surface. Our custom waterjet coil was fed with a 20 horse power mid range fire pump capable of delivering over 150 gallons of water per minute. All the water used filtered through a fine mesh material removing all the contaminants from the water supply and allowing us to recycle the water in a closed loop system.
