Automatic temperature and humidity regulation – Mixing fluid of dissimilar temperature – Plenum type
Reexamination Certificate
1999-09-30
2001-10-02
Tanner, Harry B. (Department: 3744)
Automatic temperature and humidity regulation
Mixing fluid of dissimilar temperature
Plenum type
C236S00100H
Reexamination Certificate
active
06296193
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to environmental control systems for heating, ventilating and air conditioning the interior of buildings; and more particularly, to apparatus for controlling circulation of conditioned air into a zone of a building.
BACKGROUND OF THE INVENTION
Heating, ventilating and air conditioning (HVAC) systems typically divide a large building into zones, and the HVAC system is adapted to maintain each of the zones within predefined environmental parameters (e.g., temperature, humidity, outdoor-recirculated air ratio, etc.). Each zone has a set of air distribution ducts connected to an air handling unit (AHU) that provides a supply of conditioned air to the particular zone. The air handling unit typically includes elements for introducing outdoor air into the distribution system and for exhausting air from the system. Elements also are provided to heat, cool, filter and otherwise condition the air for the zone, as well for circulating the air within the zone's air distribution ducts at a desired flow rate.
Air flow from the air handling unit to each room within the zone is regulated by a separate variable air volume (VAV) terminal unit, also called a VAV box. The typical variable air volume terminal unit has a damper driven by an actuator to vary the flow of air from the zone's air distribution duct. In a common air distribution system a single duct extends from the air handling unit to supply air at a given temperature to each variable air volume terminal unit. In order to provide air at the proper temperature for a given room, the variable air volume terminal unit has heating and cooling elements element.
The operation of the variable air volume terminal unit is provided by a VAV controller that must provide both continuous and discrete control functions. Continuous control includes a temperature loop and a flow loop, while discrete control includes the sequencing of the heating device.
Another type of air distribution system utilizes a pair of ducts to furnish heated and cooled air to each variable air volume terminal unit. The VAV terminal unit mixes air from both ducts to supply air at the proper temperature to the room. Conventional control of this dual duct system is based on sensing the temperature of the air at different point as described in U.S. Pat. No. 5,558,274.
SUMMARY OF THE INVENTION
The flow air from a hot air duct and a cold air duct into a zone of a building is controlled in based upon performing a thermal energy balance calculation for the zone. That calculation produces a heat transfer setpoint Q
sp
from which a hot air flow setpoint and a cold air flow setpoint are derived. Although the present invention is being described in terms of an air distribution system, its concepts can be applied to distribution systems for other fluids, such as for water.
In the preferred embodiment the thermal energy balance is calculated based upon a comparison of the measured temperature in the zone to a temperature setpoint which produces a temperature error signal. The heat transfer setpoint is derived from the temperature error signal. Preferably the hot cold air flow setpoints are derived from the heat transfer setpoint, the temperature of air in the hot air duct and the temperature of air in the cold air duct.
The flow of air from the hot air duct is controlled in response to the hot air flow setpoint and the flow of air from the cold air duct is controlled in response to the cold air flow setpoint. Preferably the hot air flow is varied in response to a comparison of the hot air flow setpoint to a measurement of air flow through the hot air duct, and cold air flow is varied in response to a comparison of the cold air flow setpoint to a measurement of air flow through the cold air duct.
REFERENCES:
patent: 2254185 (1941-08-01), Newton
patent: 2292335 (1942-08-01), Durbin
patent: 2747842 (1956-05-01), Shataloff
patent: 3567115 (1971-03-01), Nelson
patent: 3612164 (1971-10-01), Miner
patent: 3901310 (1975-08-01), Strawn
patent: 3933197 (1976-01-01), Zimmer et al.
patent: 4013118 (1977-03-01), Zimmer et al.
patent: 4099553 (1978-07-01), Burnham et al.
patent: 5215497 (1993-06-01), Drees
patent: 5350113 (1994-09-01), Coogan
patent: 5558274 (1996-09-01), Ben-Aissa et al.
patent: 5931227 (1999-08-01), Graves
Seem John E
West Jonathan D.
Haas George E.
Johnson Controls Technology Co.
Quarles & Brady LLP
Tanner Harry B.
LandOfFree
Controller for operating a dual duct variable air volume... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Controller for operating a dual duct variable air volume..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Controller for operating a dual duct variable air volume... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2598778