HVAC / AHU Ozonation

AHU

Ozone is increasingly being used in HVAC systems to improve the indoor air quality & also to achieve the energy efficiency of the HVAC systems. Chemtronics has successfully designed and installed oxygen fed air ozone generator to integrate with the present HVAC system. It achieves acceptable Indoor Air Quality (IAQ) while minimizing energy consumption, and fully complying with ASHRAE standards. It also helps in getting LEED rating points on Indoor Air Quality. This unique technology integration gives buy back of CapEx in less than 1 year.
 

Advantage of Ozonator in HVAC/AHU:

A) Indoor Air Quality (IAQ)
Indoor Air Quality (IAQ) is an important determinant of population health and well being. Because people spend most of their time in indoor spaces then out door. Ozone being the strongest disinfected, it helps in reducing Volatile Organic Compound & improves the Indoor Air Quality.

B) Energy Efficiency/ Economic Benefits:
i) Reduction in Capital Cost:

Use of Ozone Generator in AHU will reduce in fresh air intake results in reduction of over all HVAC plant capacity sizes:
» Chiller, Cooling Tower.
» Condenser water and chilled water pumps.
» Pipe sizes and Insulation.
» Electric / Stream Duct heaters.
» Electrical Panel & Cables.
» Stand by diesel generator.
» Plant room space.

ii) Reduction in Operating Cost due to use of Ozone Generator in AHU:
» Reduction in Energy consumption to run HVAC System
» Reduction in Water consumption to run HVAC System
» Cost of Maintenance (Labor and Material)
C) LEED / USGBC rating points on Indoor Air Quality

Use of ozone generator in AHU will help in getting the LEED rating points on Indoor Air Quality.

D) Green Air/ Sustainable Solution
Use of ozone generator in AHU will result in green air, as it is a sustainable solution.

HVAC/AHU System

AHU system takes “Outdoor/Fresh Air” to dilute Volatile Organic Compound (VOC) and reduce Carbon dioxide (CO2) within acceptable limits. Conventionally Fresh Air is used to improve Indoor Air Quality (IAQ)
But, Fresh air is not cheap!
Hot and humid air needs to be cooled down to room temperature.

Load profile of fresh air
» 60% to cool moisture … wasted energy
» 28% to cool nitrogen …..wasted energy
» 12% to cool oxygen …..the only useful component in fresh air

Solution to reduce the Fresh Air intake:
» By using controlled injection of ozone.
» Oxidation of VOC is performed by ozone and not by oxygen of the fresh air.
» Ozone is more powerful oxidizing agent than oxygen.
» In the presence of a more powerful oxidant, less powerful oxidant does not have the
   chance to perform oxidation, until no more of the former is available.
» Oxygen of the fresh air is preserved and not spent in performing the task of oxidizing
   the VOC, which is now transferred to ozone.
» Available oxygen is now used entirely to maintain CO2.
» Intake of fresh air is reduced drastically. Thus fresh air requirement goes down to 5CFM or
   less per person.

Ozone Technological
» Ozone (O3) is tri atomic Oxygen
» Ozone (O3) is a very strong disinfectant & oxidant. Any pathogen or contaminant that
  can be disinfected altered or removed via an oxidation process, will be affected by ozone.
» It is the strongest of all molecules available for disinfection

Chemtronics’ Ozone Generator

Dry Air or Oxygen is passed through the UV Generator.

Ozone Generation: Corona Discharge Method
• Ozone is produced when dry oxygen or air gas stream is subjected to high voltage/high density electrical current within a given area bounded by the electrodes generating the electrical field.

Ozone Cel
• 316 L stainless steel water cooled ozone cell
• High efficiency ceramic / quartz electrode with special high temp silver coating for long life
• High concentration up to 120 gms / m3
• Current density maintained at 0.3 watt/cm2 for maximum output and long life
• Ease of service and cleaning

Ozone injection
• Venturi injectors - Ozone is injected under vacuum creating fine bubbles and mixing efficiency can be improved using static mixers.

Medical grade Oxygen Concentrator
• Chemtronics system utilizes Nidek medical oxygen concentrators for ozone production
• Robust design ,long life and constant oxygen concentration
• Unique rotary poppet valve are more reliable than solenoid valve
• Can be coupled together for larger system (up to 1 kg/ hr)

Process Description of Ozone Generator as Air Disinfector / Air Purifier /Odour remover in HVAC/AHU Duct: -

1) Ozone generator is interlocked with AHU – Ozonator & Oxygen Concentrator starts only when AHU is on.
2) VOC sensor is installed in return air duct. When VOC level goes above preset level ozone generation starts automatically. And when VOC level falls below preset level ozonator stops generating ozone.
3) Oxygen fed Ozone generator has the following components:
a) Oxygen concentrator – It takes ambient air as a source of oxygen & concentrate oxygen to 90 to 93%, this is medical grade high purity dry oxygen.
b) Ozone generation: 90- 95% pure oxygen when fed to ozone generator. It converts oxygen into ozone by Corona Discharge Technique. This way ozone is generated outside AHU duct.
c) Sensors & Controllers: The unit has two sensor controllers, one VOC sensor & other Ozone sensor. These are programmed for safe generation of ozone & controlled dose of ozone in ambient air.
d) Injector / Diffuser – With the help of flexible tubing ozone is injected in an AHU duct, where the ozone is mixed with ambient air.
4) As a safety backup ozone sensor is installed in a supply duct. This measured the ozone built up in the system. If by any chance ozone built up goes above 80% of safe permissible limit, ozone controller prevents the ozone generation to avoid ozone built up.
5) System also has alarm to indicate if ozone built up goes above permissible limit.

Ozone Generator Equipment Specification:

1. Ozone generated shall be minimum of 8-10% wt/wt of oxygen. With medical grade oxygen as feed gas. Air as feed gas is not permissible & shall not be used.
2. Ozone generation & variation of ozone output shall be at variable frequency. Modulation of ozone at constant frequency is not permissible.
3. The equipment shall be housed outside the AHU. The ozone generator shall be floor/skid mounted with integrally pipe & wired.
4. Ozone generator shell shall be fabricated of SS316L.
a. Cylinder:
b. Gasket:
c. Dielectric: tubes shall be fabricated of ceramic to provide high efficiency dielectric.
5. All pipes in contact with ozone shall be SS316L. All other devices in contact with ozone shall be SS316L, glass silicone, PVDF.
6. All electrical components shall confirm to CSA, NEC and UL ratings. The generator shall be suitable for operation on 380V- 410V Hz. Power density shall not exceed 0.30 watts per sq.com of effective dielectric surface area.
7. Power supply unit transformers shall be dye type, class F insulated with high temperature cut-out for each phase, suitable for operation in 104degree F (40 degree C) ambient, with temperature rise not higher than 122 degree F (50degree C).
8. The PSU shall consist of the following components as a minimum, all factory wired, assembled and tested.
• 3 Phase harmonic filter to minimize total harmonic distortion.
• Three phase isolating transformer.
• Three phase fully controlled rectifier with snubbers and MOV’s (Metal Oxide Varistors) on each side.
• DC filter bank.
• IGBT inverter assembly complete with snubbers.
• Medium frequency oscillating circuit with over current and over voltage protection.
• Medium frequency dry-type transformer.
9. If operation is on medium frequency, each power supply unit shall have frequency electronic protection consisting rectifiers or invertors over current protection, over current protection, over voltage protection at the IGBT modules, and high voltage short circuit protection.
10. The Ozone generator shall be provided with emergency stop button.
11. Ozone quantum should be specific in mg/m3/ppm.

Comparison Oxygen Fed Ozonator v/s Air Fed Ozonator

Ozone Generator, Manufacturer, Supplier, Exporter: Chemtronics has successful supplier, installed & commissioned air ozonator for AHU application to achieve acceptable Indoor Air Quality (IAQ) & reduce energy efficiency & sustainable solution.