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Feed the Future Innovation Lab for Collaborative Research on Horticulture

Chimney solar dryer: How to build and use

The chimney solar dryer is designed to provide efficient drying even in hazy or partially cloudy conditions, using low-cost, widely available materials.

Designed by UC Davis researchers for the Horticulture Innovation Lab, this updated solar dryer design can help farmers add value to crop surpluses and extend access to fruits and vegetables throughout the year.

Chimney Solar Dryer Manual

Cover for the new Chimney Solar Dryer Manual from the Horticulture Innovation Lab

The new Chimney Solar Dryer Manual (PDF) from the Horticulture Innovation Lab guides readers through how to construct this low-cost technology with widely available materials. The manual also includes directions for how to use this improved solar dryer to efficiently dry fruits and vegetables.

 

How-to manual available by chapter

The Chimney Solar Dryer Manual can be downloaded as one whole document, or in separate chapters as needed.

  • Chimney Solar Dryer Manual (PDF, 5.5 MB)
    This 16-page document includes a brief introduction, directions for how to build and instructions for how to use.
  • How to Build a Chimney Solar Dryer (PDF)
    This 6-page document includes a materials list, isometric illustrations and step-by-step instructions for how to construct a chimney solar dryer.
  • Drying Fruits and Vegetables with a Chimney Solar Dryer (PDF)
    This 5-page document includes directions for how to use the chimney solar dryer to dry fruits and vegetables, with troubleshooting tips and resources for more information.

 

How does the chimney solar dryer work?

The chimney solar dryer combines solar heat collection with rapid air flow for efficient drying of fresh produce.

The chimney on this solar dryer ensures continuous air flow around the product, thus increasing the speed of drying compared to other designs. This design’s large heat-collection area (the drying table) ensures high temperatures and rapid water removal. Furthermore, the design is flexible to allow users to modify tray depth and size to fit local demands.

Building a chimney solar dryer

There are four main components of a chimney solar dryer:

Materials to build the chimney solar dryer include wood pieces, wood or bamboo poles, clear polyethylene (greenhouse-grade plastic), black plastic or black fabric, and food-grade mesh. The dryer dimensions can be changed to meet specific needs. The dryer should be built in a flat area with good sun exposure available for the entire dryer.

Drying fruits and vegetables with a chimney solar dryer

Once you have built a chimney solar dryer, you will want to test the dryer to make sure it is working well and that there are no leaks or gaps in the plastic.

Thin items like herbs and leafy greens may dry in a few hours, while large products like whole apricots or whole bananas will require several days to dry. You can decrease drying time by removing pits, peeling the product, and/or cutting it into thin slices.

The manual includes considerations for placing the product in the chimney solar dryer and conditions that will affect performance of the dryer.

 

Designing the chimney solar dryer

Michael Reid and James Thompson, UC Cooperative Extension specialists with UC Davis, designed the chimney solar dryer initially for a solar dryer contest.

Researchers with the Horticulture Innovation Lab have built and used versions of the chimney solar dryer with farmers in the United States, Ghana, Guinea, Kenya, Tanzania, Bangladesh, Thailand, Guatemala and Honduras.

 

Fact sheets and blog posts about the chimney solar dryer

In addition to the manual, there is a one-page fact sheet with basic information about the chimney solar dryer, its uses and benefits: Solar drying adds value to crop surplus (PDF)

Researchers with the Horticulture Innovation Lab have built the chimney solar dryer on three continents, which you can learn about in these recent blog posts: Blog posts related to the chimney solar dryer

 

Related drying technologies

Drying can be an important part of postharvest handling, processing and storage for both food and seed. The Horticulture Innovation Lab has worked with a number of drying-related technologies, including:

 

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We are working on some videos about the chimney solar dryer and other supporting materials. If you would like to be notified when these materials are available, we recommend that you sign up as a subscriber to the Horticulture Innovation Lab's email newsletter.