'Nduja di Spilinga
Soft, spreadable Calabrian pork sausage made with a great deal of red chilli and fatty pork, stuffed into natural casings, sometimes smoked and matured while staying soft.
Built structures · Drying kilns and dryers
UC Davis chimney solar dryer
A passive solar dryer built as a long black-covered table with a clear-film chimney that draws air over mesh trays. The University of California Davis 2018 manual gives its cut list and build steps.
What it is
The UC Davis chimney solar dryer is a passive crop dryer with four parts: a black-covered table that absorbs sunlight, a clear-plastic chimney open at the top, mesh trays, and a clear polyethylene cover sealed across the table and the chimney. The table and the chimney together make a single air path, so the design needs no fan or power.
The manual gives an example with a 4 m table and a chimney rising 2 m above the table. It supplies a full material schedule with member labels A to M, a step-by-step build and troubleshooting notes. The archived university page summarises the components and the orientation but is not a separate design.
How the air moves
Ambient air enters at the low front opening, flows over the trays and the product, passes through a rectangular opening in the chimney film above the table, and rises up the chimney. The table faces the equator, with the chimney at the opposite end. The manual warns that leaks where the table and chimney meet let air bypass the trays. It recommends stakes and guy ropes on windy sites.
The table absorbs sunlight and warms the air beneath the clear cover. The chimney uses the warm air's tendency to rise to keep the flow moving, so the chimney height matters to the airflow.
Sources for this section
Dimensions and materials
The manual states that its material schedule is calculated from the actual dimensions and suggests adding about 10 per cent extra material. It labels the lumber 3 by 3 cm, but it does not match that label to a regional stock standard, and it gives no joint clearances or tolerances. The sizes recorded here are the sizes printed in the manual.
Changing the size of the dryer changes its airflow, so a scaled version has to keep the table, chimney and opening in proportion rather than shrinking every part by the same factor. The sources do not give a rule for that scaling.
Sources for this section
Building it and what remains open
The manual builds the table and the chimney separately, joins them with attachment boards, cuts the chimney opening, seals the film, stakes the frame and makes the trays. It does not name the saw or drill models, so tool choice is left to the builder.
The build list is complete but the dryer is not ready for a site. Before a build guide calls it ready, the stock sizes need matching to the regional lumber, the safe use of each tool needs specifying, the chimney opening size and the stability and anchoring need resolving. A prototype should then log inlet, product and outlet temperature and humidity with empty and loaded trays, and test the cover, rain shedding, condensation and cleaning. Those tests describe the dryer, and they do not validate any food process.
Sources for this section
History
The Horticulture Innovation Lab at the University of California Davis published a six-page manual, How to Build a Chimney Solar Dryer, in 2018. The archived university page summarises its four components and orientation.
Site
SettingOpen, sunny ground. The manual orients the table to face the equator: south in the northern hemisphere and north in the southern.
GroundThe four corners are staked. No foundation or ground preparation is specified.
ClimateThe design is a sun-drying crop dryer. Wind needs guy ropes, and humid weather slows drying.
FootprintTable 4 m long, 80 cm wide and 60 cm high. Chimney 60 cm wide and 60 cm deep, 2.8 m tall, rising 2 m above the table.
NotesThe manual's envelope is for the example build. Other sizes change the airflow relationships, so a scaled version needs its own check.
A build is made where it stands: moving it means building it again.
How it is built
Risks and precautions · Standard risk
Bypass air at the table and chimney joint
A leak at the joint lets air skip the trays, so the product dries unevenly and the dryer loses its airflow.
Hazard sourceWind damage
A tall chimney on a light frame can be blown over in a strong wind unless it is staked and guyed.
Hazard sourceSeal the film to the chimney and table, and fit stakes and guy ropes at the four corners
Control sourceThe manual describes a crop dryer. Its suitability for meat or fish is not established.
Keep the mesh food-contact suitable; a frame of any material does not excuse a non-food-grade tray mesh.
Materials
- Lumber, 3 by 3 cm (as printed) — Cut to the member lengths in the manual: table top slats 54 cm (23 pieces), chimney uprights 2.8 m (4), table rails 4 m (4), table and chimney members 74 cm (8), diagonal braces 95 cm (3) and 1.6 m (2), stabilisation boards 1.5 m (3), pole-support shelves 60 cm (2).
- Lumber, 2 by 4 cm (as printed) — Tray rails, 60 cm (40 pieces, for 10 trays), and table strips, 4 m (2 pieces).
- Lumber, 2 by 15 cm (as printed) — Table-to-chimney attachments, 90 cm (2 pieces), and pole supports, 30 cm (2 pieces).
- Clear polyethylene sheet, 0.10 to 0.15 mm — A 2.2 by 3 m sheet for the chimney and a 4 by 3 m sheet for the table cover.
- Black table sheet or fabric — A 6 by 2.7 m piece, fixed to the table top as the absorber.
- 10 pieces Food-grade mesh — Each piece 60 by 60 cm, stapled taut over a tray frame.
- Fasteners — Staples for film and mesh, screws for the table-to-chimney joints, and nails for the tray corners.
- Guy ropes and stakes — Four corner stakes and guy ropes for windy sites.
- Build the table and the chimney as separate frames, using the member schedule.
- Staple the black sheet to the table top and the clear film to the chimney.
- Connect the table and the chimney with the two attachment boards and screws, and fit the pole supports and shelves.
- Cut a rectangular opening in the chimney film above the table.
- Drape clear film over the centre pole and seal it to the chimney and the table, so air cannot bypass the trays.
- Stake the four corners, and add guy ropes where the wind is strong.
- Make the trays from the tray-rail members, stretch food-grade mesh taut over each frame, square the frame, and trim any sharp mesh edges.
Places
No source in this record establishes a place.
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Sources
UC Davis Horticulture Innovation LabMethod · History · Safety
How to Build a Chimney Solar DryerFour components: black-covered table, clear chimney, mesh trays and clear polyethylene cover.
Example with a 4 m table and a chimney rising 2 m above the table; member labels A to M with cut lengths.
Leaks at the table and chimney joint cause bypass flow; stakes and guy ropes for windy sites.
Material schedule suggests about 10 per cent extra material; lumber labelled 3 by 3 cm.
Cited in: What it is; How the air moves; Dimensions and materials; Building it and what remains open
UC Davis Horticulture Innovation LabHistory
How to build a chimney solar dryer (archived university page)Summarises the four components and the table orientation.
Cited in: What it is