Another Task 29 project is found in India where a solar air preheating system has been installed at the Kaveri Agri-Care Pvt. Plant in the Hassan District of India to assist in the drying of coir pith.  Coir Pith is a byproduct manufactured from the powder found on coconut shells.  At the plant, the raw material is soaked in water for about one hour to remove the sodium.  Following this, the coir pith is mechanically pressed to reduce the moisture content to about 70%.  Final drying then occurs in a fluidized bed dryer which reduces the moisture content to 20%.  The finished product is marketed as Core Peat or Green Soils for use as a potting soil substitute as it absorbs about 12 times its weight in water and will hold moisture 8 times longer than standard soils.  The product floats and is also used as an oil absorbent.

Perforated Solarwall panels cover 414m2 of the roof of this facility.  Air is drawn through the small openings in the panels at 60 m3/hr/m2 where it is heated to approximately 20ºC above ambient.  The air is then ducted to the burner where the temperature is raised to the required 105ºC to feed the dryers.

The selection of a solar air heating system is an excellent fit for this project.  It meets the client’s need to replace diesel fuel which is rising in cost, it does not add further pollution to the local environment and it does not adversely affect the product.  Furthermore, the system has long operating hours, operates year round and only requires moderate temperatures.

The system has been operating successfully in the eyes of the client for three years.  Preliminary calculations indicate that the solar system displaces approximately 14% of the heating fuel, yielding a 2 year pay back.  This project was not monitored by the Task due to resource limitations.

Exterior of coir pith drying facility

Perforated solar panels mounted on the roof

Coir pith was once considered a useless waste material