Patent Application
20100219258
The present invention relates to a system for disinfection and aromatization of heating, ventilation and air conditioning (HVAC) systems. More particularly, the invention relates to a system for automatically and regularly disinfecting and/or aromatizing HVAC ducts, and the air that flows through them, wherein embodiments of the invention operate independently of the HVAC system.
Broadly speaking, heating, ventilation and air conditioning (HVAC) systems include a centralized heating and/or air-conditioning unit connected to a blower motor that circulates heated or cooled air throughout a building via ducts. Centralized systems enjoy widespread use in a number of settings including buildings, cruise ships, and other suitable transportation vehicles, due to a number of advantages such systems have over unit ventilators and/or individual heat pumps or heaters. For example, centralized HVAC systems are quieter, less drafty due to multiple air supplies and an air return that is away from room occupants, easier to maintain due to relatively few components and often have space for higher efficiency air filters. In operation, much of the air within a building is recirculated while mixing the recirculated air with fresh air from an external source. Such recirculation reduces overall energy costs because the recirculated air need not be continuously heated or cooled from the outside ambient temperature, and need only be maintained at the proper interior temperature.
The recirculation of air, however, has certain drawbacks. Although HVAC systems have air filters to remove particulate matter from the airstream, the ventilation ducts of the HVAC system can become contaminated with bacteria, viruses and/or molds thereby contaminating the airflow which is directly sent into rooms where people are breathing. Contaminated HVAC ducts have been associated with so-called Sick Building Syndrome (SBS) as well as with Norwalk virus contamination on cruise ships. It is, therefore, necessary to take steps to prevent contamination, or once contamination has taken place, to disinfect the ductwork.
In the past, prevention of duct contamination has often required a complete shutdown of the HVAC system, sometimes for days, and laborious and expensive manual cleaning of the ducts. To help eliminate the need for this expensive and time consuming decontamination and/or prevention process, systems have been developed to permit at least semi-automated disinfection of HVAC ducts by introducing disinfectants into the air stream flowing through the ducts. Such systems have likewise been used to introduce aromas into the air stream flowing through the ducts, in order to aromatize the environment.
For example, U.S. Pat. No. 6,065,301 (“the '301 patent”) describes a system for introducing cleaning and/or aromatizing agents into the airstream of an automobile air-conditioning system. The system described in the '301 patent, however, relies on the driver to manually initiate the introduction of the agents by pushing a button. This method of manual introduction is not ideal because it is possible to push the button, and therefore introduce the agents, even when the airflow through the air-conditioning system is either too weak or nonexistent. Under such conditions, the cleaning or aromatizing agent could collect in the system without being distributed by an airstream. Also, manual introduction of the cleaning or aromatizing agent may lead to too much or not enough of such agents being introduced into the airstream. In other words, there is no correlation between the volume of air flowing in the system, and the amount of disinfectant or aromatizing agent being introduced.
U.S. Pat. No. 5,957,771 describes a mechanism that is integrated into the ventilation ducts of a central HVAC system, and permits introduction of an aromatizing agent into the ventilation airstream. The described mechanism, however, is wholly integrated into the central HVAC system and relies upon signaling and control from the central HVAC system itself in order to operate. Moreover, and similar to the '301 patent described above, the mechanism does not detect airflow speed or mass in order to control the amount of aromatizing agent introduced in the airstream.
U.S. Pat. No. 5,302,359 describes an apparatus for introducing an aromatizing agent into the airflow of an HVAC system. The aromatizing liquid is pumped into an absorptive material which is located inside the ventilation duct, and where the aromatizing liquid is then evaporated from the absorption material into the airstream. This apparatus has significant drawbacks. For example, the rate of evaporation from the absorptive material is difficult to predict and highly variable depending on the specific agent being used, and the air temperature and humidity of the airstream. Because of this, the amount of aromatizing agent being introduced into the airstream is also not correlated with the amount of air flowing through the ducts. Also the aromatizing agent is pumped into the absorptive material at predetermined intervals even if there is no airflow in the duct. If, for whatever reason, the airflow to the ducts is interrupted for an extended period of time, an excess of agent may overflow the absorptive material into the ducts.
International Patent Application No. PCT/DE2003/002757 describes a device which is connected to the central control module of a building ventilation system, and controls the introduction of disinfectant and/or aromatizing agents into the HVAC airstream. Because the described device relies on a connection to the central control module of the building ventilation system, the described system may not be readily retrofitted to existing HVAC systems and must instead be specifically engineered for whatever HVAC system is in place. The described device also does not disclose any means for detecting the specific amount or speed of airflow in the HVAC ducts. It is therefore not possible for the described device to accurately meter disinfectant or aromatizing agents into the airstream in a manner that is a function of the airflow.
There is therefore a need for a system that automatically aromatizes and/or disinfects an HVAC system by detecting and measuring the airflow through the HVAC ducts, and injecting an appropriate quantity of aroma or disinfectant agent into the airstream as a function of the measured airflow and independently of the HVAC system itself.
a is an isometric view of an HVAC injection apparatus according to an embodiment of the invention.
b is an enlarged front elevational view of the control module 120 showing in
a is an enlarged, isometric view of the duct airflow and injection interface module 110 as shown in
b is an enlarged, side view of the duct airflow and injection interface module 110 according to an example installation on an HVAC duct 105.
a-3e are a series of operational flow charts depicting operation of an HVAC injection system or apparatus according to an embodiment of the invention.
Embodiments are described below for automatically injecting a disinfectant or aromatizing agent into the airflow of an HVAC system. Although described in terms of a particular combination of components, it should be understood that such components are only exemplary. Other types of components may also be substituted in other embodiments of the invention.
An HVAC injection apparatus 100 according to an embodiment of the invention is shown in
b depicts the control module 120 according to an embodiment of the invention. The control module 120 includes a housing 138. The control module housing 138 includes a cable jack 150 to interface with the cable 135 shown in
a depicts the duct airflow and injection interface module 110. The duct airflow and injection interface module 110 includes an airflow sensor 230 and the injection nozzle 220. Also shown is the cable and hose conduit 112 which couples the duct airflow and injection interface module 110 to the housing 115 as shown in
b depicts an enlarged side view of the duct airflow and injection interface module 110 coupled to the HVAC duct 105. This figure more precisely illustrates the physical arrangement of the airflow sensor 230 and injection nozzle 220 with respect to the HVAC duct 105. In particular, the airflow sensor 230 extends into the HVAC duct 105 upstream of the injection nozzle 220 to avoid the injected liquid wetting the airflow sensor and impacting its reading of airflow. The airflow sensor 230 is thus situated to detect the presence of airflow and measure the speed and/or mass of air flowing within the HVAC duct 105. In a typical embodiment, the airflow within the HVAC duct 105 is created by a fan or blower 255 within the HVAC system such as shown in
In one embodiment, the injection nozzle 220 may function so as to aerosolize the disinfectant or aromatizing agent 250 during injection of the agent into the HVAC duct 105. Aerosolizing the agent during injection results in relatively large droplets of agent being present in the airstream. In other embodiments, however, the injection nozzle 220 may instead atomize the agent 250 during injection into the HVAC duct 105. Atomization of the agent during injection results in much smaller droplets of agent being present in the airstream. The choice of whether to aerosolize or atomize is application specific and also depends somewhat on the specific type of disinfectant or aromatizing agent 250 being used.
In an embodiment, the injection nozzle 220 may be an electromagnetic injection nozzle. An electromagnetic nozzle has certain advantages for this application. For example, a suitable electromagnetic injection nozzle has an electromagnetic valve integrated into, or inherent to, the operation of the electromagnetic injection nozzle. Functionally speaking, when the electromagnetic injection nozzle 220 stops injecting fluid into the HVAC duct 105, the electromagnetic valve closes in a very short period of time, typically on the order of 100 ms. The rapid closure of the electromagnetic valve ensures that there is no leaking or dripping of the agent 250 into the HVAC duct 105 after the injection nozzle 220 stops operating. The closure of the electromagnetic valve in the injection nozzle 220 also ensures that no liquid returns to the reservoir when the injection nozzle 220 stops operating. This functionality is useful because when the time comes for the injection nozzle 220 to again begin spraying agent 250 into the HVAC duct 105, it takes very little time for the pump 125 to bring the system up to full pressure. Likewise, the use of an electromagnetic injection nozzle eliminates the need to re-prime the system and/or bleed any air out of the system between uses or refilling of the reservoir 130. Additionally, a rapid duty cycling of the electromagnetic nozzle 220 ensures that the fluid stream “breaks up” which results in a wider and more efficient agent injection into the HVAC duct 105. Lastly, the use of an electromagnetic injection nozzle permits more precise dosing of the agent into the HVAC duct 105. Although the use of electromagnetic injection nozzle has certain advantages, it should be noted that other types of injection nozzles are suitable for use with embodiments of the invention.
Specific operational aspects of the embodiments shown in
With reference to
Supposing, for example, that the user selects setup manual mode 316 from the menu, the process flow of an example setup manual mode is depicted in
Again with reference to
If the user selects the setup system options 322 from the menu, process flow used is depicted in
The setup system function 322 also permits the user to set or change the PIN number of the control module 120 at block 346. Once the PIN number has been set or updated at block 346, the data associated with the new PIN is persisted to the data store 349.
Block 344 of the setup system options 322 allows the user to specify whether units will be displayed as Imperial units or metric units. Once the unit type has been specified, the data associated with unit type is persisted to the data store 349 and the control module 120 thereafter displays data with the appropriate units.
As discussed above, in the automatic spray mode, the system determines the amount of agent 250 to inject into the HVAC duct 105 as a function of the mass of air flowing through the HVAC duct 105 per unit time. The mass of airflow in the duct per unit time may be computed by multiplying cross-sectional area of the HVAC duct 105 by the flow rate of air through the duct as determined by the airflow sensor 230. The cross-sectional area of the HVAC duct 105 is computed based on data provided in the setup system options 322 starting at block 334. At block 334, the user is prompted to specify whether the HVAC duct 105 is a round duct, or square duct. If the user specifies a round duct at step 334, process flow passes to block 336 where the user is prompted to input the radius of the duct. The cross-sectional area of a round duct is then computed and persisted to the data store 349 at block 338. If instead the user specifies a square duct at step 334, process flow passes to block 340 where the user is prompted to input the width and depth of the duct. The cross-sectional area of a rectangle or duct is then computed and persisted to the data store 349 at block 342. After the user has completed any one of these operations in the setup system mode, system operation may pass back to the setup system options 322, or in other embodiments, back to block 310 of the main menu to choose a mode and/or other set of parameters as shown at block 350 of
After system setup has completed, or anytime after the system is turned on and the PIN correctly entered, the user may elect to enter system run mode 312 from block 310 as shown in
The system operates to spray disinfectant or aromatizing agent 250 into the airflow in the HVAC duct 105 only when airflow is detected in the HVAC duct. The detection of airflow by use of the airflow sensor 230 is not dependent on any control signal from, or mechanical interface with, any equipment which is a part of the HVAC system with which the HVAC injection apparatus 100 of the present invention is used. Embodiments of the HVAC injection apparatus 100 thus provide independent operation without the HVAC injection apparatus risking interfering with the HVAC system, its electronics or mechanical elements, or requiring alteration of the HVAC system. The HVAC injection apparatus 100 of the present invention is a stand-alone unit and is easily added with minimal effort to existing HVAC systems, and uses real-time airflow measurement.
From the foregoing it will be appreciated that, although specific embodiments of the invention have been described herein for purposes of illustration, it will be understood by one skilled in the art that various modifications may be made without deviating from the invention. Accordingly, the invention is not limited except as by the appended claims.
