Electric heating – Heating devices – Combined with container – enclosure – or support for material...
Reexamination Certificate
2000-10-06
2002-04-09
Pelham, Joseph (Department: 3742)
Electric heating
Heating devices
Combined with container, enclosure, or support for material...
C219S400000, C312S236000
Reexamination Certificate
active
06369362
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to equipment, thermal equipment and more particularly to high efficiency equipment for controlling heat and humidity as well as to take advantage of the heat capacity, density and flow of humid air. The structural embodiment of the invention is an improved single and double sided doorless humidity cabinet.
BACKGROUND OF THE INVENTION
Thermal equipment, particularly thermal equipment in use in the food industry, will ideally require as precise a thermal and humidity control as possible. Because of the required ease of transport of food, most such equipment must have high user access, typically a rack of trays for quick removal for use in loading, bringing to temperature and maintaining temperature. Tray loading and storage usually requires a wide opening such as a door which provides a continual stream of upset to the internal environment. A unit of equipment needs to have the ability to adjust from a condition of intermittent and continual usage. The food items recently added should come to a good temperature and humidity condition quickly.
Complicating this goal is the physics associated with the inside of the unit of equipment. Where hot air sources and heating elements are present, there is a danger that the dry heat will harden the food, and that the moist heat will condense on the food to make the food soggy. These are the extreme limits of wrong operation. More common are the closer limits of wrong operation in that food on horizontal racks for example, in the upper reaches overheats and dries out, whereas food on the lower reaches experiences condensation and is too cool.
Physical and scientific limitations on a common space for environmental control are not only difficult to maintain, but monitoring in order that control may be effected is also problematic. Temperature probes without more don't indicate moisture. One hundred eighty degrees of moist heat can cause heat and moisture penetration into food to bring the food to its final heated and moist condition more quickly. The same temperature of dry heat could cause hardening and spoilage of the food in a fraction of the time.
Application of heat is another problem. Where a pan is heated, no benefit is had unless it is certain that water is present, and unless it is certain that the humidity reaches the other areas of the cabinet. Where a dry heating element is energized, the amount of heat leaving the element before shut off depends upon the moisture, and therefore total heat capacity of the volume of air in the unit of equipment. Thus, temperature alone will not give an indication of how much thermal energy has been introduced. Humidity alone will not give an indication of how much thermal energy has been introduced, and neither will it enable a projection based upon usage of the equipment for quick additional moisture and thermal input.
Another problem with conventional equipment configuration is the vented cabinet. Where a vent is provided, the cabinet continuously emits a mixture of moisture and air representing losses in energy due to the raised temperature of the exiting components compared to ambient temperature, and the energy which must be added to to vaporize water to replace the humidity lost from the vent. Vented systems also have a physical limitation as to where they can be placed to insure that the vented exit does not cause condensation on other equipment or walls, and that the condensation exit is not blocked as it would upset the steady state temperature and moisture movements within the unit, and likely cause the food to become water laden or soggy.
SUMMARY OF THE INVENTION
The thermal environment equipment and process of the present invention is illustrated through structures and processes described with respect to a single and double sided ventless humidity cabinet, and which may also optionally be a doorless humidity cabinet especially if access occurs often enough such that operating a door would be an efficiency distraction, and is a working assembly made up of a number of component parts. The components for full illustration number sixteen, and include: cabinet box (housing), wet heating element(s) or wet heat source, water temperature probe, inlet valve, drain valve, level sensor(s), water, water level, Dry heating element(s) or dry heat source, upper temperature probe or upper humidity probe(s), middle temperature probe(s) or middle humidity probe(s), lower temperature probe(s) or lower humidity probe(s), air curtain fan(s) both to isolate the warm moist air inside from the dry cooler air outside, and to provide internal circulation to the internal environment more even, doorless entry window(s), arrows showing laminar air flow direction forming air curtain and then mixing steam with dry heat, and a special customizable wall that is normally only included in double sided unit.
The cabinet box for the ventless system is preferably made of a rigid material such as metal or plastic and should be capable of safely holding hot water and steam with minimum ambient thermal loss through the cabinet walls. The ventless steam cabinet shape most commonly is box shape; however, for design efficiency or visual savvy can be any shape or size as long as it can hold its humidity and perform the function of producing steamy humid environment for the products contained within. Ventless indicates that there is no deliberate vent for vapor and hot air, and that any escape of heated vapor air mixture is with the removal of food, or through leakage from the doorless opening, mitigated by the air door or air guarding flow at the service opening.
The inlet valve allows for the water to flow into the cabinet box and can be manually or electronically controlled. The level sensor(s) is a device or devices that establish when the correct water level, the optimum amount of water in the unit, has been reached. The level sensor is also a device that detects where the water is in the system. If the water level is too low or too high, it will detect it, take an action, and could also generate error signals for other problems with the water level. The level sensor can range from a simple float to a remote sonic, infrared, heat, electric, electronic, or other means of establishing the water level. The water is heated with the wet heating element(s) or wet heat source which can be water immersible electric heating elements, gas heat, microwave, electronic, light, or other kind of heat generating method or source. The water temperature probe detects the temperature of the water. The water temperature probe can be a simple thermistor to an infrared, electronic, or other means for attaining water temperature. The drain valve allows for the water to flow out of the cabinet box and can be manually or electronically controlled. The steam from the water in the cabinet box provides a portion of the heat and most of the humidity.
The dry heating element(s) or dry heat source which can be air electric heating elements, gas heat, microwave, electronic, or other kind of heat generating method or source and is used to dry out air and generate heat or dry hot air for the cabinet. The dry heating element(s) or dry heat source is most often placed at the top of the cabinet; however, this does not have to be the case and other methods of injecting dry heated air into the cabinet box could be used.
The upper temperature probe(s) or upper humidity probe(s), middle temperature probe(s) or middle humidity probe(s), and lower temperature probe(s) or lower humidity probe(s) detects the amount of humidity, dry heat, and temperature generated and how well the dry air and wet steam are mixing. The upper temperature probe(s) or upper humidity probe(s), middle temperature probe(s) or middle humidity probe(s), and lower temperature probe(s) or lower humidity probe(s) can be a simple thermistor, humidity sensor to an infrared, electronic, or other means for attaining humidity and temperature. The upper temperature probe(s) or upper humidity probe(s), middle temperature probe(s) or middle humidi
Harrington Curtis L.
Pelham Joseph
LandOfFree
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