Walmsley T., Walmsley M., Atkins M., Neale J., 2014, Thermo-Economic Assessment Tool for Industrial Milk Spray Dryer Exhaust Heat Recovery Systems with Particulate Fouling, Chemical Engineering Transactions, 39, 1459-1464.
This study reports the development of an Excel spreadsheet based tool for performing a thermo-economic assessment of milk spray dryer liquid coupled loop exhaust heat recovery. Incorporated into the tool is the ability to predict the level of milk powder fouling over time and its impacts on heat transfer and pressure drop. Focus is given to finned round tubes, and round and elliptical tube geometries without fins. Modelling results show that spray exhaust heat recovery is economically viable for the industrial case study considered. Based on the results, the best liquid coupled loop heat exchange system uses a finned tube heat exchanger to recover heat from the exhaust air with a face velocity of 4 m/s and 14 tube rows, which gives a NPV of NZ$2.9 million and an IRR of 71 %. The tool has the ability to cater to site specific needs that affect the utility savings and the capital cost for implementing exhaust heat recovery. It is anticipated that this tool will provide confidence to the New Zealand dairy industry to uptake exhaust heat recovery.
