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SolarFlex Fruit and Vegetable Dryer

In partnership with Malnutrition Matters, SolarFlex Inc. has developed an innovative solar fruit and vegetable dryer that has a flexible design and is inexpensive to manufacture. Drying fruits and vegetables with this system is a cost-effective long-term food storage solution that requires no external electricity to operate, and eliminates the need for chemical preservatives.

Additionally, this system will be of interest to entrepreneurs looking to provide dried food products in markets where food security is not an issue. The very low production costs associated with dried foods make this method highly cost-competitive compared with foods preserved through other methods. Dried fruits and vegetables are also regarded as premium specialty foods in many markets. In addition, the system can process many other kinds of food products, such as dried fish and herbs.

fruit racks
Drying racks with various fruits, before drying

dried fruit
Fruits after drying

New "Small Farm" Dryer

 

Currently completed as a new prototype, this model has three main features which will enhance drying speed and efficiency. This compact configuration provides for:

• Horizontal air flow across the food being dried.
• Solar air collector tilts to accommodate any latitude or season.
• Dryer can swivel on a table so operator can rotate unit to track the sun.

Drying rack total area is 5.1 sq. M, which is suitable for 10–15 kg. of “wet” food, depending on water content, thickness of product, etc. 30 watt photovoltaic panel drives 4 DC circulation fans.

Beta models will be available by May 2011 and technology transfer / distribution partnerships will be developed in Africa, Asia and Central America/Caribbean. Estimated price $1,200.

Prototype (shown on work table) with collector set at 30 degrees.


Prototype with collector set at 0 degrees.

FAO Demonstration and Training Systems
St. Lucia, Caribbean, March 2011

Under the terms of an agreement between FAO and Malnutrition Matters, for the provision of SolarFlex food dryers, two different models were installed in March by MM tech specialist Charles Lauzon. At Fond Assau, both the traditional vertical style and the newly designed horizontal SolarFlex “Small Farm” dryer were installed and operated with a team designated by the St. Lucia Ministry of Agriculture. The terms of the agreement call for additional trials and data collection over at least 8 weeks. This will establish tropical performance information for various kinds of fruits, vegetables and herbs and also compare the vertical and horizontal data. 


Horizontal and Vertical SolarFlex dryers set up at Fond Assau, St. Lucia
Early trial results prove that the new horizontal design is superior during full sun conditions. This is partially due to the ability to rotate the dryer to face the sun throughout the day, but also because of its airflow characteristics. The traditional style vertical design performed somewhat better on semi cloudy days, but nevertheless was a more expensive system to build and ship. The overall economics and performance favour the horizontal version.
SolarFlex horizontal “Small Farm” model. Tilting solar air collector can angle to any solar angle and latitude. The whole system can rotate on the table to face the sun throughout the day.
Dryer being loaded with sliced pineapple. 8 racks with stainless steel mesh can be loaded with up to 20 kg of wet fruit – depending on type of fruit, thickness of slice etc. Normal target is same day drying but this depends on the length of the sunshine / day and other variables such as ambient humidity, type of food etc.
Dried mango and “sourey” sour fruit, ready to package and store for many months in simple plastic bags. These are highly valued, healthy snacks and help provide food security for seasons where some fresh products are not available.