@article{lentz_kolar_classen_2019, title={Valorization of Swine Manure into Hydrochars}, volume={7}, ISSN={2227-9717}, url={http://dx.doi.org/10.3390/pr7090560}, DOI={10.3390/pr7090560}, abstractNote={There is a significant interest in valorizing swine manure that is produced in enormous quantities. Therefore, considering the high moisture content in swine manure, the objective of this research was to convert manure slurry into hydrochars via hydrothermal carbonization and analyze the yields, pH, energy contents, and thermal and oxidation kinetic parameters. Experiments were performed in triplicate in 250 mL kettle reactors lined with polypropylene at 180 °C, 200 °C, 240 °C, 220 °C, and 260 °C for 24 h. Analyses of the results indicated that the process temperature affected the hydrochar yields, with yield generally decreasing with increasing temperature, but it had little effect on the composition of the hydrochar. The hydrochars were found to have higher volatile contents and H/C and O/C ratios and about 85% of the energy compared to coal. However, the presence of high fraction (35–38%) of ash in hydrochars is a serious concern and needs to be addressed before the complete utilization of hydrochars as fuels. The surface characterization of hydrochars coupled with wet chemistry experiments indicated that hydrochars were equipped with nitrogen functional groups with points of zero charges between 6.76 and 7.85, making them suitable as adsorbents and soil remediation agents and energy storage devices.}, number={9}, journal={Processes}, publisher={MDPI AG}, author={Lentz, Zac and Kolar, Praveen and Classen, John J.}, year={2019}, month={Aug}, pages={560} }
 @article{lentz_classen_kolar_2017, title={THERMOCHEMICAL CONVERSION: A PROSPECTIVE SWINE MANURE SOLUTION FOR NORTH CAROLINA}, volume={60}, ISSN={["2151-0040"]}, DOI={10.13031/trans.12074}, abstractNote={Abstract. The growth of North Carolina’s swine industry in recent decades has led to a subsequent increase in the production of swine manure. This manure represents a potential threat to environmental and human health, as well as an opportunity to add value to pork production. Technologies for treating swine manure safely while generating products to offset costs are part of an expanding field of research centered on sustainable food production for our growing population. Thermochemical conversion processes use heat to degrade organic feedstocks and drive chemical reactions, which generate valuable products. The high moisture content of swine manure is prohibitive for most thermochemical processes, but gasification and hydrothermal carbonization may be more accommodating. Gasification, a time-tested thermochemical conversion process, yields a combustible gas through a series of endothermic reactions, and hydrothermal carbonization yields a solid, coal-like char that can be used as a fuel or chemical precursor. Advances in thermochemical conversion processes have indicated the potential for yielding valuable products from swine manure, but viable scalable processes are still under development, requiring further research to apply these processes to swine manure management and evaluate the usefulness of their products. This review (1) describes, generally, thermochemical conversion via both hydrothermal gasification (HTG) and hydrothermal carbonization (HTC), (2) shows the usefulness of each conversion process for biomass, and (3) discusses the potential of HTG and HTC of swine manure to enhance the value of pork production. Keywords: Energy, Gases, Hydrothermal carbonization, Hydrothermal gasification, Pig manure, Pigs, Sustainable.}, number={3}, journal={TRANSACTIONS OF THE ASABE}, author={Lentz, Z. and Classen, J. and Kolar, P.}, year={2017}, pages={591–600} }
 @article{shah_lentz_van heugten_currin_singletary_2017, title={Tempering ventilation air in a swine finishing barn with a low-cost earth-to-water heat exchanger}, volume={9}, ISSN={1941-7012}, url={http://dx.doi.org/10.1063/1.4979359}, DOI={10.1063/1.4979359}, abstractNote={An earth-to-water heat exchanger (EWHE) can reduce livestock heat stress and also save electricity and water. A 4-kW EWHE system comprising 154 m of a polyvinyl chloride (PVC) pipe (35 mm ID) buried in 3.2 m of soil was evaluated for its ability to provide cooling to 60 pigs in a finishing barn in Raleigh, NC. A low-cost tube-and-fin heat exchanger was used to exchange energy between water (38 l/min) and air (0.58 to 1.22 m3/s). After 8 h of cooling, at 1.22 m3/s, the temperature change (ΔT), energy produced (qh), and coefficient of performance (COP) were as high as 3 °C, 4.3 kW, and 8.2, respectively. After 12 h of continuous operation for air tempering during winter, |ΔT|, |qh|, and COP were 2.2 °C, 3.4 kW, and 6.7, respectively. While the EWHE pens were slightly warmer than the Control pens cooled with stir fans and sprinklers on very hot days, pig performance in the EWHE pens was unaffected. The EWHE reduced the electricity use by >50% and eliminated the sprinkling water use. Burying plastic pipes in slinky coils instead of using double pass rigid PVC pipes could improve system performance as would wetting the soil around the pipes. In addition to being sustainable, the EWHE could be cost-effective for zone-cooling of high-value pigs as well as greenhouse cooling in many parts of the world.}, number={2}, journal={Journal of Renewable and Sustainable Energy}, publisher={AIP Publishing}, author={Shah, Sanjay B. and Lentz, Zachary A. and van Heugten, Eric and Currin, Richard D., Jr. and Singletary, Isaac}, year={2017}, month={Mar}, pages={023901} }