B17: Heat Recovery from Aerated Static Composting Systems

The Ohio Department of Rehabilitation and Corrections approached our senior design team with the idea of capturing heat from compost piles for use in heating water or buildings. Their facility is roughly half a football field in size, containing agricultural and food waste. Compost piles are able to reach temperatures upwards of 160°F, to the point of inducing thermal deactivation of the microbes within the pile. Removing heat from the compost system could both supply energy to the facility, while also preventing thermal inactivation.
Our team designed a prototype heat recovery system that could be constructed at the Miami University Institute for Food. This consisted of an insulated compost bin with a heat exchanger and aeration system. For composting substrates, we selected horse manure and partially decomposed yard waste in  approximately equal amounts. Temperature readings of the pile show high exothermic activity in the first few days, which eventually start to drop, characteristic of the composting process. To test the performance of the heat exchanger, it was run for 30 minutes periodically, monitoring the temperature increase of the water tank connected to it. We were able to recover much more energy than what was required to run it. Tests with the aeration system turned off show an even larger rate of heat transfer, indicating that aeration exhausts a large amount of heat from the pile. We are currently looking into how to optimize our design which may include adding a recycle loop for aeration system. Additionally, we are developing a model for this process in Simulink.

Author(s): Evan Danielson, Chemical Engineering and Music Performance Major 

Preston Beach, Chemical and Paper Engineering Major 

Paul Carter, Bioengineering Major 

Ben Champagne, Engineering Management Major 

Gretchen Day, Chemical and Paper Engineering Major 

Will Baldwin, Engineering Management Major 

Tai Goddard, Chemical and Paper Engineering Major 

Sarah Kubican, Bioengineering Major 

Jessica Lutz, Engineering Management Major 

Denali Selent, Engineering Management and Environmental Science Major 

Justin Tirtadjaja, Chemical and Paper Engineering Major 

Advisor(s): Catherine Almquist, Department of Chemical, Paper, and Biomedical Engineering 

Jason Berberich, Department of Chemical, Paper, and Biomedical Engineering 

Alim Dewan, Department of Department of Chemical, Paper, and Biomedical Engineering