Feed-back Temperature Control System for Microwave Ovens Using a Shielded Thermocouple

Authors

  • H. RAMASWAMY,

    1. Authors Ramaswamy and van de Voort are with the Dept. of Food Science, and Authors Raghavan and Lightfoot are with the Dept. of Agricultural Engineering, Macdonald College of McGill Univ., Box 187, St. Anne de Bellevue, Québec, Canada, H9X 1C0
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  • F.R. VAN DE VOORT,

    1. Authors Ramaswamy and van de Voort are with the Dept. of Food Science, and Authors Raghavan and Lightfoot are with the Dept. of Agricultural Engineering, Macdonald College of McGill Univ., Box 187, St. Anne de Bellevue, Québec, Canada, H9X 1C0
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  • G.S.V. RAGHAVAN,

    1. Authors Ramaswamy and van de Voort are with the Dept. of Food Science, and Authors Raghavan and Lightfoot are with the Dept. of Agricultural Engineering, Macdonald College of McGill Univ., Box 187, St. Anne de Bellevue, Québec, Canada, H9X 1C0
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  • D. LIGHTFOOT,

    1. Authors Ramaswamy and van de Voort are with the Dept. of Food Science, and Authors Raghavan and Lightfoot are with the Dept. of Agricultural Engineering, Macdonald College of McGill Univ., Box 187, St. Anne de Bellevue, Québec, Canada, H9X 1C0
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  • G. TIMBERS

    1. Authors Ramaswamy and van de Voort are with the Dept. of Food Science, and Authors Raghavan and Lightfoot are with the Dept. of Agricultural Engineering, Macdonald College of McGill Univ., Box 187, St. Anne de Bellevue, Québec, Canada, H9X 1C0
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  • This research was supported by a grant from Conseil des Recherches en Peche et Agro-alimentaire du Quebec (CORPAQ MCA grant #2570).

ABSTRACT

A dynamic system was developed and evaluated to continuously monitor product temperature in ovens using an aluminum shielded thermocouple. The signal was processed by a computer controlled feedback relay to turn the magnetron on or off relative to a preselected setpoint. Results indicated the temperature of water (> 100 mL) could readily be maintained within 1°C of the setpoint. Temperatures for small samples (∼5 mL) could also be controlled, however, they required use of an additional microwave heat-sink in the oven cavity to prevent temperature overshooting. The thermocouple based feed-back temperature control system worked well and provided a simple way to control sample temperature in a microwave oven.

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