Indoor air quality gas phase return air cleaner

Details Indoor air quality gas phase return air cleaner Indoor air quality gas phase return air cleaner

1998-02-26

2002-08-13

Tran, Hien (Department: 1164)

Chemical apparatus and process disinfecting, deodorizing, preser

Chemical reactor

Waste gas purifier

C422S168000, C422S169000, C422S170000, C422S172000, C422S108000, C422S110000

Reexamination Certificate

active

06432367

ABSTRACT:

FIELD OF THE INVENTION
This invention relates to the field of air conditioning and cleaning and, more particularly, to improved indoor air cleaning methods and systems for compliance with National Indoor Air Quality Standard ANSI/ASHRAE 62-1989.
BACKGROUND OF THE INVENTION
The World Health Organization furnishes data showing measured levels of up to 0.4 mg/m
3
of ozone and 1.0 mg/m
3
for NO
2
in workplace indoor air which is well over the acceptable limits for ozone and approaching acceptability level for NO
2
. When one considers the known ability of commonplace office equipment to produce such gases through the ionization of air within the equipment, one can readily appreciate that improvements in indoor air cleaning are needed to meet the levels set forth in the Standard.
Those familiar with the production of ozone for commercial purposes are aware that in addition to ozone the equipment also produces nitrogen oxide and nitrogen dioxides through the same ionization process which produces ozone. It is equally well known that electronic equipment, which has become so common to the office worker environment, produces ozone in a similar fashion as the IEEE requires certification that equipment produced according to it protocols is certified to emit no more than 0.1 ppm of ozone.
SUMMARY OF THE INVENTION
The invention disclosed herein is a two stage air cleaner configured to control levels of both ozone and nitrogen dioxide concentrations where such air contaminants are propagated within the workplace to preclude substantially degradation of indoor air quality provided by HVAC (heating-venting-and air conditioning) systems. These pollutants are known to be propagated through the use of electronic equipment and operations which ionize air within workplaces which use such equipment.
The invention operates in a unique sequential manner upon air induced through its intake section wherein water droplets are initially intimately mixed with contaminated air, to absorb any soluble nitrogen dioxide conveyed within the airstream and then, once the air has been suitably mixed into a drier, but higher humidity controlled condition, through the evaporation of all free moisture suitable to react its ozone content. Continuous mixing, as taught herein, in a mariner which assures adequate molecular contacts between ozone and molecular water for a gas-to-gas phase reaction to replicate a process known to quench ozone. Hence, ionized gas contaminants of an air stream traveling through the inventions envelope specifically engineered to assure the transfer of the electronic charge of the ionized gases to the grounding path which the invention's enclosure provides is cleaned of the cited pollutants.
This two step air cleaning process is new art uniquely created to satisfy the ANSI/ASHRAE 62-1989, Indoor Air Quality Standard which governs what is, and is what is not acceptable workplace air quality with respect to the ionized gases produced within the workplace, which otherwise would render that air unsuitable for recirculation through standard HVAC (heating-ventilating and air conditioning) system configurations. ASHRAE 62-1989, the American Society Of Heating, Air Conditioning and Refrigeration Engineers, is the peer group professional society charged with responsibilities for establishing standards of practice for those who design, construct, maintain and manage buildings.
The ANSI/ASHRAE 62-1989 Standard publishes limits for commonly known building pollutants, as concentrations listed within its Table C-1, lists the ozone and nitrogen dioxide permissible exposure limits along with many other potential pollutants.
FIG. 1
, as reproduced from the Standard shows possible locations to which an air cleaning device may be applied. The alternate methodology for controlling pollutants specified within the Standard relies on increasing ambient air rates to purge pollutants to the acceptable levels through dilution. The invention applies the principles of air cleaning only to the return air cleaning task as the most effective way of achieving compliance with the Standard with respect to the ionized gases which have been cited as common to workplace usage.
FIG. 1
also illustrates an occupancy wherein a source generates a pollutant and how the invented return air cleaner is applied to mitigate, or otherwise remove the pollutants to preclude the reintroduction of the contaminated air back into the occupancy. While the invention is one of many air cleaners which might be applied, it is specific only to ionized gases as previously cited. Without application of the invention, not only would the source emissions increase, but any recycled ones as well, through cycles-of-concentration. Cycles-of-concentration result from the recirculation of HVAC system air operated to minimize the costs associated with heating and cooling the large air masses required to comfort condition and ventilate workplaces served by central HVAC systems.
Hence, the return air cleaner, as set forth herein, will react the ionized gases out of the return air stream which acts to zero-out the complex cycles of concentration component of the indoor air ability equations of Appendix E of the Standard.
While the invention deals with nitrogen dioxide, a primary focus is on the ozone which invariably accompanies nitrogen dioxide, both gases being formed from an ionization process and not products of combustion which are considered the usual source of nitrogen dioxide. Current OSHA labor law cites ozone at 0.1 ppm as the TWA exposure limit. Nitrogen dioxide is similarly limited to 5.0 ppm at present. Hence, control of ozone level is one of the invention's primary objectives because the World Health Organization has published detection levels of up to 0.2 ppm of ozone measured as a building air quality pollutant.
ASHRAE has documented that ozone propagation is directly related to the concentration of water molecules which act to inhibit the ionization process as have the manufacturers of commercial ozone generators and these have provided key factors in developing the invented return air cleaner.
The invented return air cleaner acts to control ozone levels in a two fold manner. First, by inerting the ionized gases traveling through the return-air-cleaner (RAC). A direct control mechanism. Second, by reducing the propagation rate of the electronic equipment located within the occupancies through the elevated moisture content of the substantial recirculated air component which has been mixed with ambient ventilation air in accordance with the teachings of the Standard itself. An indirect control mechanism.
It is the sum total of both of these effects which is needed to control the level of ozone within the workplace served by the HVAC system within which the return air cleaner is applied.
In general the commercial and industrial HVAC systems in use today circulate a thermally conditioned air stream composed of 75 to 80% recirculated air and 20 to 25%, ambient air sourced ventilation air. This invention is particularly suitable to upgrade such HVAC systems for compliance with ANSI/ASHRAE 62-1989 by controlling cleaning rates to what are the currently documented safe occupancy exposure levels of these gases. Hence, the invention disclosed herein is a return air cleaner applied in accordance with the teachings of the Standard which can become the optimum technology to satisfy the requirements of the Standard. Cleaning the air from office type occupancies by making it safe for recirculation in quantities of about 80% of the entire air mass distributed by the HVAC systems to maintain safe and healthy workplaces with acceptable indoor air quality as defined by the ANSI/ASHRAE Standard with respect to ozone.
The invented RAC is the alternate technology to dilution ventilation which can be energy intensive as compared to working with the respective dilution rate formulas of the Standard. Such comparison reveals that a RAC application substantially diminishes ventilation rates to those established within the Standard and promises to be the most c

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