Welcome to Chili's
Project undertaken in course year 2018-2019 with Precourt Institute for Energy
Project Goal
Develop an ergonomic and inexpensive racking system for the existing chili dryer that promotes faster and more uniform drying
Project Motivation
The dryer developed in 2018 course (Spice to Meet You) was successful in protecting chilis from rain, pests and UV radiation while decreasing drying time. However the dryer lacks a proper racking system that best utilizes its space and function, and chilies are not uniformly dried within it
Background
India produces over 45% of the world's dried chili peppers and a majority of farmers use traditional sun drying techniques
There is a wide temperature gradient that exists within the dryer, resulting in uneven drying across batches of chilies within the dryer
existing racks
High Priority Requirements
All materials must be food safe when exposed to a temperature range of 20-70 C
Dry the chilis more uniformly than the current racks with at least 90% of the chilies being top tier quality
No more than 25kg shall be transported at any one time
Farmers should spend no more than 5 contiguous minutes inside the greenhouse during the hottest part of the day to avoid prolonged exposure to extreme heat
Total cost under $1000 for 2000 kg of chilis and all parts should be locally sources, on Amazon.In, or IndiaMART.com
Ethical Considerations
Food Safety
Worker safety
Dependence on foreign technology
Causing a rift between farmers that can afford the new technology and those that can't
Environmental effects
Solution
We settled on a backpack-inspired rack, versatile enough to help transport and dry produce, that can be used as a vertical hanging garden in the chili off-season. Once hanging inside the dryer, our rack btter utilizes its existing temperature gradient by lifting the chilis up to a hotter temperture and having the ability to be flipped, exposing each shelf within the back to the same overall mean temperature experience
Wearing the Pack
The chili rack can be worn as backpack enabling simple transport
Existing Dryer
The dryer, scaled up to 500 kg capacity in India
Inside the Dryer
The current racks are stacked, shown in red, in the drying portion of the dryer
Temperature Gradient
Cross-sectional view of existing dryer showing temperature gradient within the dryer. The black rectangles depict placement of current racks
Thermal test setup
Test chamber was created to test the rack under development, as compared with existing rack systems. Note that the backpack is also suspended, to physically raise the chilies into the higher temperature zones of the dryer
Finished prototype
The backpack, shown hanging as it would in the dryer. The back also carries a hook at the bottom so it can be easily hung from the bottom, flipping the chilis
Thermal result
Tests measured % mass loss in drying, by shelf position comparing the backpack results to the current racks, over 8 hour test. Prototype resulted in 1.6x water loss as compared to the current system
Other testing conducted
Finite Element Analysis model of stress and deformation of shelves within the drying rack (survives 20-70C env)
Loading and unloading time of chilis from pack (5 min, with design proposal to reduce to 3.5min)
Time spent in dryer to hang the pack (47s average, <5min reqmt)
Cost of materials to fabricate the pack ($8.41/ea. A 2000kg dryer would require 80 packs, so total cost < $1000 requirement)
Student team
Future Work
Iterate on door open/closing mechanism
Manufacture another prototype in India
More user/thermal testing
Create instructional videos on how to use product