Infrared heating control
AssigneeDonald P. Smith
InventorsDonald P. Smith, J. E. High, William W. Plumb
Life of this patent
Estimating the term…
Abstract
A process and apparatus for heating food products under a temperature and humidity controlled atmosphere, the apparatus employing intermittent microwave heating in combination with infrared sensors adapted to initiate and terminate heating in response to measured changes in the temperature of the food product as a result to heat conduction to the center of the product while the microwave heating unit is turned off.
Claims18
A process for changing the temperature of a food product to a desired temperature, comprising the steps of:
- moving the food product through a series of cavities in a chamber;
- maintaining the temperature and relative humidity of air in the chamber to establish a predetermined wet bulb temperature in a controlled ambient atmosphere around the product in the chamber;
- measuring infrared radiation from the surface of the food product while the product is in the controlled ambient atmosphere in a first cavity to determine the temperature of the surface of the product;
- initiating transfer of heat between the food product and a source of heat through the controlled ambient atmosphere in a second cavity until the surface of the product reaches a predetermined temperature;
- terminating the transfer of heat between the product and the source of heat when the surface of the product reaches the predetermined temperature;
- holding the product in the controlled ambient atmosphere for a predetermined time period;
- measuring the temperature of the surface of the product at the expiration of the time period;
- and resuming transfer of heat between the product and the heat source in a third cavity in response to a specified change in the temperature of the surface of the food product during the time period.
Apparatus to heat a food product comprising:
- a heating chamber;
- a floor in said heating chamber, said floor having perforations formed therein;
- tubes communicating with said perforations to project spaced discreet streams of air into said chamber;
- a return duct extending longitudinally of the chamber, said floor having exhaust passages formed therein communicating with the inside of the chamber and the return duct;
- a plenum extending longitudinally of said chamber, said plenum and said return duct having a partition therebetween, said partition having an opening in a lower portion thereof;
- water in lower portions of the plenum and the return duct, said opening being positioned to permit flow of water between the plenum and the return duct;
- means to deliver air from said plenum into the chamber;
- means to exhaust air from said chamber;
- means controlling the temperature and humidity of the atmosphere adjacent the surface of the product in the chamber;
- infrared energy sensing means;
- heating means to transfer heat to a product in the chamber;
- and control means associated with the sensing means and with the heating means to terminate transfer of heat to the product when the temperature of the surface of the product is above a predetermined temperature.
Apparatus to controllably heat each of a plurality of food products wherein the heating required to obtain the desired heating varies with volume, shape, initial temperature, porosity, moisture content and composition of the products, the improvement comprising:
- a heating chamber, partitions in the heating chamber to form a plurality of heating cavities;
- a conveyor extending through said heating chamber to sequentially move products through said heating cavities;
- means controlling the temperature and humidity of the atmosphere adjacent the surface of products in each cavity to control the wet bulb temperature of the atmosphere in the cavity to control evaporation of moisture on the surface of the product in the cavity;
- infrared energy sensing means in a first of said cavities;
- heating means to transfer heat to a product in a second of said cavities;
- and control means associated with said infrared energy sensing means in said first cavity associated with said heating means in said second cavity to control heat transfer to the product in the second cavity based on the sensed condition of the product in the first cavity.
Dependencies are inferred from the claim text.