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Highly Energy Efficient Heat Treatment of Food Using Magnetic Induction Heat Generation

By George Sadler, Founder, PROVE IT, LLC

As high-priced petroleum-based energy is increasingly supplanted by alternative-source electric, (nuclear, hydroelectric, solar, hydrogen, wind,) high efficiency electric heating will inevitably make petroleum-fired boilers obsolete.

Contemporary boilers are bulky, require mechanical vigilance, demand physical isolation from the processing floor and have a notoriously large carbon footprint. Even in efficient processing plants with excellent thermal recovery, only 20% of the energy supplied as bulk fuel ultimately becomes food heat. Steam transfer losses account for much of the remaining 80%. Processing facilities must often use additional energy to remove waste heat. Currently, liquefied petroleum gas (LPG) is the preferred fuel source for steam boilers.

A therm of LPG is about 50% as expensive as a therm-equivalent of peak-use electricity. The therm-equivalent off-peak cost of LPG and electricity is approximately equal. Therefore, a peak-use electric heating alternative to steam heat must deliver 40% of its energy as food heat to compete with the prevailing boiler-heat model of thermal processing. Using off-peak electric would provide further operating economy.

Magnetic induction heating in contrast allows high efficiency conversion between electricity and food heat. Passive thermal diffusion transfers heat between the inductively-heated tube bundle and the food. In the present design, 80% of the electric supply energy directly heats the tube bundle with subsequent transfer to the food. The remaining 20% appears as heat in the induction coil and electronics of the induction unit. A water cooling system captures this heat and uses it to preheat product entering the heating stage.

Preliminary tests indicate that 95% of the electric supply energy can be captured as food heat when magnetic induction is coupled with energy recovery from the coil and electronics. A commercial system operating as this efficiency would observe an immediate 2 to 5 fold energy savings and could potentially reduce its carbon footprint to 0.

It is believed that replacement of steam boilers with induction heat would reduce energy loss with concomitant increases in energy savings. Additional advantages versus steam are sturdiness, low-price, portability, ease of cleaning, training ease, amenable to computer control, flexible interchange of tube bundles designed for various viscosity products and space savings. The unit also makes inroads into developing processing technologies for the inevitable all-electric energy future.

George Sadler is the Founder of PROVE IT, LLC (Packaging Regulation, Optimization, Validation and Education for Innovative Technologies) which develops and achieves FDA validation for innovative packaging and processing technologies. He has 20 years of academic experience dealing with technical and regulatory issues related to food packaging. Dr. Sadler received his PhD from Purdue University and has held faculty positions at University of Florida and Illinois Institute of Technology. He has specialized in technical and regulatory issues involving polymer recycling, irradiation of food contact polymers, and the use of migration models for assessing dietary exposure for indirect food additive submissions to FDA. His research interests include active and intelligent packaging, experimental approaches for assessing migration, and the impact of novel food processing technologies on packaging performance. For article feedback contact George at gsadler@proveitllc.com.

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