HVAC Evaporative Pads with Chitosan

Product: HVAC Evaporative Pads with Chitosan
Development Stage: Prototype Tested
Primary Inventor: Andro H. Mondala, Chemical & Paper Engineering Department
Scientific Publication: Mondala et al. TAPPI IBBC Conference, Sept, 2014, Tacoma, WA    
License Status: Available for Licensing       
Patent Status: US 9982393 
Reference:  2015-008

photo of chitosan panels

chitosan panels

Currently, Phenol resins are widely used in corrugated and paperboard products as barrier coatings. A thinner phenol resin coating is used on paperboard for specific HVAC applications, such as evaporative cooling pads for agricultural livestock enclosures, where the air permeability is important for cooling efficiency. However, the wet stiffness and water absorption rate provided by this coated paperboard is low, making its use, less desirable.

While other coating options like wax, extruded polyethylene, or acrylic resins are used, as with phenol resin, their untimely structural breakdown, low evaporative cooling performance and a lack of recyclability of the coated paperboard makes all these coatings expensive and less practical.

A natural biopolymer like chitosan is an environmentally friendly alternative to other coatings, as it is biodegradable, has low toxicity, and the coating process uses no volatile organic compound (VOC) or petroleum-based barrier coating chemistries. Chitosan is a plentiful coating material because it is derived from crustacean shell chitin or from the cell walls of fungi.

Technology Description

Researchers at WMU have created an efficient process for producing chitosan for coatings via fungal fermentation with soybean and soybean waste. The researchers created a cooling pad with a single layer chitosan coating that is one-quarter the cost of the phenol resins and requires less coating weight, making the evaporative cooling pad lighter. They found that their cooling pad has better wet stiffness, wicking height, and water absorption, and is more air permeable than phenol resins for improved evaporative cooling.
During testing, the wet stiffness was initially found to be identical for the chitosan and phenol resin coated pads. After two days of immersion in water, the wet stiffness for the chitosan coated pad increased by 13% while the wet stiffness of the phenolic resin coated pad decreased by 7% due to the loss of the coating.
In addition, the chitosan can be applied as a single layer using environmentally benign methanol and acetic acid solvent or combined as an additive to the evaporative cooling pad as it is manufactured.

Potential Benefits

•    Better performance parameters than phenolic resins: wet stiffness, wicking height, water absorption, air permeability
•    Reduces operating costs for agricultural livestock enclosure HVAC systems
•    Environmentally friendly coating and recycling of paperboard
•    Requires simple, inexpensive coating equipment and control system

Downloadable version


D. Clark Bennett 
(269) 387-8218
Director of Technology and Innovation Advancement