The present invention is directed to a device for humidity reduction as a precursor to small-scale ozone generation.
Ozone (O3) is a gas derived from oxygen which can be readily dissolved in water, where it is referred to as Aqueous Ozone (which has no odor or color). Ozone is an EPA approved antimicrobial oxidizer, sanitizer and disinfectant, and Aqueous Ozone is an effective micro-flocculent and effective anti-foaming agent. Indeed, the disinfecting capability of 1 PPM Aqueous Ozone is equivalent to many times (10 to 15,000 times) the concentration of free available chlorine, depending on pH, temperature, and on the specific microorganisms to be destroyed. Ozone is produced by an ozone generator at the point of use (utilizing only air and electricity) and converts back to oxygen leaving no harmful byproducts making it both a green and sustainable technology. Ozone is an approved organic food additive under the USDA National Organic Program. Ozone is an EPA Approved Antimicrobial, Disinfectant & Sanitizer by definition and ozone performs these functions as an oxidizer.
Ozone Generators have been in use in residential pools since the early 1980s. In the early days, the systems had a wide size range of ozone outputs, but as the popularity evolved, they became relatively small. Today, the most common ozone systems create between 0.2-0.5 grams of ozone per hour (some even less). Although some ozone is better than no ozone, these systems do not provide enough ozone to be as effective as they could or should be. Ozone reduces the use of chlorine and ancillary chemical additives dramatically which offers a healthy swimming environment and beautiful pools.
Ozone gas can be produced by passing air (or oxygen) through a light energy field or electrical energy field in a chamber. Generally, there are three types of ozone generators or ozonators that are used in spa and swimming pool disinfection. 1) Corona Discharge Generators, 2) Ultra-Violet Light Generators, and 3) Plasma or MicroPlasma Generators.
CD (Corona Discharge) Ozone is ozone produced with electrical energy (high voltage/low amperage). The quantity and concentration are substantially higher, and the energy cost is much lower than UV Ozone. In the CD ozone generator machines, air is exposed to multiple high voltage charges. The air in the system contains 20% oxygen and 80% nitrogen. The corona discharge ozonator systems are very cost effective and do not require an oxygen source, other than the ambient air. Unfortunately, when these types of ozonators are used, they produce nitrogen oxides as a by-product. To reduce or eliminate the formation of nitric acid, a desiccant air dryer is used to remove water (moisture) vapor from the air. Instead of an air dryer, an oxygen concentrator may be used to further increase ozone production and at the same time, reduce the risk of nitric acid formation by removing both moisture and the bulk of the nitrogen from the air. Nitrogen, typically in the form of nitric acid, reduces ozone production and creates corrosion and clogging of ozonators.
UV (Ultraviolet) Ozone is ozone produced with light energy (˜185 nm wavelength); the quantity and concentration are very limited, and the energy cost is high. However, UV ozone generating system work well in very high humidity air environments, and may be less expensive as they may not require any off gas mechanisms, desiccant air dryer systems or oxygen concentrators.
Plasma or Microplasma Ozone is the next generation in ozone production. Plasma produces a “uniform glow discharge,” as opposed to Corona Discharge, which is a “random discharge,” making more ozone with less energy, in similar sized units. In so-called “cold” plasma ozone generators pure oxygen is exposed to a plasma that is created by a dielectric barrier discharge, and the diatomic oxygen is split into single atoms. A cold plasma ozone generation system produces a far greater quantity of ozone in a given time period than a UV generator would, but is very expensive. Cold plasma ozone generators utilize pure oxygen as the input source and produce an ozone concentration of about 5%. Microplasma Ozone systems utilize a micro-channel ozone process, and have the potential for high conversion rates of air to ozone. The input can be ambient air, though nitrogen oxides are often produced requiring periodic maintenance.
Since roughly 2012, many Advanced Oxidation Processes “AOP” Systems have flooded the market for pool sanitizers. AOPs in a broad sense, are a set of chemical treatment procedures designed to remove organic (and sometimes inorganic) materials in water and wastewater by oxidation through reactions with hydroxyl radicals (.OH). The term AOP usually refers more specifically to a subset of such chemical processes that employ ozone (O3), hydrogen peroxide (H2O2) and/or UV light. In an effort to offer the industry something different, some companies have combined small ozone generators with small UV sterilizers and call them AOP. Based on these ozone generator and UV outputs, again, so-called AOP production rates are insignificant and do not offer a quantifiable benefit for residential pools.
There remains a need for a more efficient and productive system for ozone generation for small-scale applications such as swimming pools, commercial aquariums and food preparation facilities where ozone is used as a disinfectant.
It is an object of the present invention to improve performance of ozone generators by dehumidifying only the air that enters the ozone-generating cell, for air-fed ozone generators. The system includes a solid-state electronic dehumidifier (SSED) upstream from an ozone generator that removes moisture from ambient air to maintain rated ozone output performance. The SSED uses the process of condensation with a Peltier heat exchanger to remove water from ambient air. In order to condense the water out of ambient air it needs to come in contact with a surface that has a temperature below the dewpoint. While the dewpoint varies based on humidity, temperature, and atmospheric pressure, it is always lower than or equal to the ambient air temperature. By removing moisture upstream of the ozone generator, the SSED stabilizes the ozone generator's rated ozone output. Reducing moisture content in the process gas (air), increases unit performance, and the lifetime of the ozone-generating cell is increased by reducing nitric acid generation.
The advantageous use of the SSED directly feeding dehumidified air to an ozonator enables higher ozone output with less nitric acid generation, and thus less frequent need for servicing the ozonator. Moreover, the particular design of the SSED allows the components to be relatively small and inexpensive, which leads to greater availability for the average residential pool owner. Larger systems may be scaled up for public pools, of course.
A further understanding of the nature and advantages of the invention will become apparent by reference to the remaining portions of the specification and drawings.
Features and advantages of the present invention will become appreciated as the same become better understood with reference to the specification, claims, and appended drawings.
and
The present application is directed to a system for generating ozone which is more efficient and productive for small-scale ozone generators.
Overview
Gaseous ozone production (ozone production in the gas phase as opposed to forming ozone in the liquid phase) for various residential and commercial applications is an on-demand and on-site process since the ozone gas naturally decomposes over minutes to hours depending on the temperature and constituents of the gas. The efficiency and concentration of ozone gas produced by ozone generators depends on the quality of starting gas which is typically ambient air or oxygen and is typically in the 0.01% to 10% ozone by weight. For low-cost applications ambient air is the preferred starting gas since the oxygen source or generator can add significant costs to the ozone system. For gas ozone generators that use air for generating ozone, the humidity of the air influences ozone generation efficiency, ozone concentration, and also typically affects the longevity of the ozone generator. In general, higher ambient humidity results in reduced ozone output, lower ozone concentration, and shorter product lifespan. Therefore, it is important to have cost effective ways to reduce the humidity of ambient air before it enters the ozone generator.
Having the air cooler than ambient will also help ozone production as this is dependent on temperature. In general, gaseous ozone generators are more efficient and produce a higher concentration of ozone as the temperature of the air is reduced.
The SSED 24 is bifurcated into two internal vertically-oriented chambers—a cold side chamber 28a and a hot side chamber 28b by a vertical central wall or panel 30. A heat exchange unit 32, such as a Peltier Cooler, is secured in an aperture 54 (
In use, the hot side fan 38 pulls ambient air into the upper inlet 39 on the hot side chamber 28b. Because the hot side chamber 28b is closed at its upper end, the air is blow downward past the evaporation fins 34. At the lower end of the hot side chamber 28b, as best seen in
Different systems may move air through the conduit 25, upper exit port 50, cold side chamber 28a, and a particulate filter 42 such that the general direction of air flow is shown by the flow arrows in
The Peltier Cooler heat exchange unit 32 is a solid-state active heat pump which transfers heat from the cold side chamber 28a of the device 24 to the hot side chamber 28b. The heat exchange unit 32 usually has a flat form factor and is enabled by supplying a DC voltage and current (not shown). When operating, one side of the heat exchange unit 32 becomes hot and the other side becomes cold. When the hot side chamber 28b of a heat exchange unit 32 is maintained above ambient temperature then the cold side chamber 28a will become colder than ambient temperature. The difference in temperature from the hot side to cold side is based on the Peltier Cooler's specific characteristics and the rate that heat is added to or taken away from its surfaces. The Peltier Cooler is desirably compressed between the condenser sink 36 and the hot heat sink 34. A layer of thermally conductive material 33 can be installed between the Peltier Cooler 32 and each heat sink 34, 36 to aid in thermal conductivity, and an insulation layer 35 (incorporated in the wall 30) can be placed between the hot and cold heat sinks to improve efficiency.
Consequently, the evaporation fins 34 heat up above ambient and the condensation fins 36 cool down below ambient. This causes moisture to condense on the condensation fins 36 and drain down into the collection cup 40 which dehumidifies the air passing through the conduit 25 to the ozone generator 22. Preferably, the collection cup 40 is shaped like a shallow funnel to channel the condensate to a single outlet nozzle 41.
In an alternative embodiment, a second cold chamber 28a is stacked next to the first cold side to provide a second evaporation/dehumidifying step. Although not shown, this may be desirable to enhance the efficiency of the entire system without having to include a much larger cold sink.
The SSED 24 treats air at a rate of 1 to 50 liters per minute. In one embodiment, the housing 26 is roughly 5 inches long (tall) by 4¼ inches wide on the exterior and can process air flow of about 10 liters per minute (LPM). More generally, small-scale dehumidifiers as described herein are preferably between 4-8 inches long (tall) by 3-6 inches wide, and have a depth of between 2-4 inches. Such an SSED 24 is suitable for connection to an ozone generator 22 which produces a minimum of 2 grams of ozone per hour (GPH). The disclosed SSED 24 is configured to produce 1 to 50 LPM of cool dry air. The SSED 24 limits the relative humidity in the process air to below 50%, and more preferably to between 20-30%.
Advantageously, the disclosed SSED 24 produces an air flow rate of about 11 LPM into an ozone generator 22 such as the MP5 (Air) Smart Ozone System to generate about 2 GPH of ozone, sufficient for a residential pool. Scaling up to an air flow rate of 50 LPM would enable ozone production of about 10 GPH, enough for larger public pools, for example. Systems requiring larger amounts of ozone, such as those for industrial processing, require concentrated oxygen as an input for the ozone generator.
One beneficial attribute is being able to remove water without freezing it which can cause a decrease in air flow as ice can impede the air flow path. The SSED 24 cold side chamber 28a allows for entry of ambient air, followed by cooling of the air with the surface of the cold heat sink 36, which then flows through a sealed passage through the condenser to the ozone generator 22. As the air cools below the dew point, water droplets form on the heat sink, drain down into the collection cup 40 and reduce the humidity of the treated air.
The cold chamber 28a is sealed or isolated on one end with just the exit port 50 leading to the conduit 25 where the dehumidified air is plumbed into the ozone generator 22. The housing 26 has a very specific size to make sure that the air flow is slow enough to allow adequate time for the water to condense out of the air. The condenser sink 36 is sized to the chamber 28a and has a specific length to allow the maximum contact with the incoming air. The Peltier Cooler heat exchange unit 32 was chosen to allow for a large enough temperature drop from the hot side to the cold side and is actively controlled with a microcontroller such that it will not freeze the water on the condenser. The hot side heat sink was chosen to ensure adequate heat removal. Under the influence of gravity, the condensed water is then captured by a portion of the housing at the lowest spot (collection cup 40) to allow for disposal. The small fan 38 is preferably attached to the hot side chamber housing 46 to assist with heat removal.
One reason for the efficient functioning of the SSED 24 without freezing of air is that the fan 38 is only provided on the hot side chamber 28b, in conjunction with a passive flow upward across the cold side chamber 28a. Prior dehumidifiers utilize fans on both hot and cold sides.
Although cooling and condensation of water drops the moisture content of the air, it still remains at high relative humidity. The cooled air must be re-heated to drop the relative humidity to provide a benefit to the ozone generator. This can be achieved by using heat from the hot side of the Peltier cooler or allowed to warm through a length of tubing, or by adding an electric heater. This will ensure the air entering the ozone generator will have lower relative humidity.
In order to improve efficiency of the device, the condensed water from the condenser can be transported to the hot side to aid in evaporative cooling of the hot side of the heat pump. In this embodiment the cool side can be placed above the hot side and the condensed water can be gravity fed to the hot side of the device which would be below the cool side.
In another modification, the conduit 25 leading to the ozone generator 22 may be warmed by the Peltier element 32. For instance, the conduit 25 may be detoured back into the hot side chamber 28b and past the Peltier element 32 before continuing on to the ozone generator 22.
SSED
The collection cup 40 mounts to the bottom of the cold side housing. A line 49 can be connected to the collection cup 40 which allows for condensed water to drain from the device.
The divider plate 30 separates the hot chamber 28b and cold chamber 28a and has a rectangular cut out 54 in which the Peltier Cooler heat exchange unit 32 closely fits and makes direct contact with the condenser sink 36 and evaporative sink 34. The hot side housing 46 contains the evaporative sink 34 and has the mounts for the fan 38. Also, housings are sealed together to form airtight chambers.
As seen in
Electronic monitoring of ambient air temperature, humidity, and pressure as well as monitoring of the cold-side temperature give information to an embedded microcontroller to control power to the device to prevent freeze-up under certain atmospheric conditions.
The SSED 24 can be a stand-alone unit to dehumidify air going into the ozone generator 22, or incorporated into the ozone generator and sold as a single system.
The system 80 is shown mounted within a shed or enclosure 94 next to the pool 92. The small size of the components 82, 84 facilitates placement of the system 80 in close proximity to the other pool system components, and lends itself to widespread acceptance in the market. No special mounting considerations apply, and since the SSED 82 dehumidifies ambient air, no additional components such as oxygen generators or air dryers are required, thus reducing costs. Moreover, feeding the dehumidified air directly into the ozone generator 84 greatly improves efficiency and reduces detrimental formation of nitric acid in the generator, which in turn reduces maintenance needs over the long term.
Both the SSED 82 and ozone generator 84 are sealed in a robust fashion so as to be rated for outdoor use. To date there are no outdoor dehumidifiers for residential pool use that are rated for outdoor placement, and certainly no small-scale outdoor dehumidifiers such as the disclosed SSED 24. Various regulatory agencies such as the National Electrical Code (NEC) and National Electrical Manufacturer Association (NEMA) promulgate standard rating systems that define the types of environments in which an electrical enclosure can be used, and frequently signifies a fixed enclosure's ability to withstand certain environmental conditions. The SSED 82 and ozone generator 84 both meet various such standards as defined in the U.S. and abroad, which will be collectively known as being “exterior rated.”
Throughout this description, the embodiments and examples shown should be considered as exemplars, rather than limitations on the apparatus and procedures disclosed or claimed. Although many of the examples presented herein involve specific combinations of method acts or system elements, it should be understood that those acts and those elements may be combined in other ways to accomplish the same objectives. With regard to flowcharts, if present, additional and fewer steps may be taken, and the steps as shown may be combined or further refined to achieve the methods described herein. Acts, elements and features discussed only in connection with one embodiment are not intended to be excluded from a similar role in other embodiments.
As used herein, “plurality” means two or more. As used herein, a “set” of items may include one or more of such items. As used herein, whether in the written description or the claims, the terms “comprising”, “including”, “carrying”, “having”, “containing”, “involving”, and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases “consisting of” and “consisting essentially of”, respectively, are closed or semi-closed transitional phrases with respect to claims. Use of ordinal terms such as “first”, “second”, “third”, etc., in the claims to modify a claim element does not by itself connote any priority, precedence, or order of one claim element over another or the temporal order in which acts of a method are performed, but are used merely as labels to distinguish one claim element having a certain name from another element having a same name (but for use of the ordinal term) to distinguish the claim elements. As used herein, “and/or” means that the listed items are alternatives, but the alternatives also include any combination of the listed items.
Those skilled in the art will appreciate that various changes and modifications may be made to the preferred embodiments, the invention in its broader aspects is not limited to the specific details, representative devices, and illustrative examples shown and described.
The present application claims priority under 35 U.S.C. § 119 to U.S. Provisional Application No. 62/906,439, filed Sep. 26, 2019, the contents of which are expressly incorporated herein.
Number | Date | Country | |
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62906439 | Sep 2019 | US |