Optimal TFA (Treated Fresh Air) Solutions: Balancing IAQ and Energy Efficiency

Executive Summary

1. Challenges of Fresh Air Handling in Modern HVAC

In the context of increasingly elevated Indoor Air Quality (IAQ) standards, HVAC design engineers and investors face a dual challenge: ensuring user health while controlling operational energy costs.

1.1. The Burden of "Latent Load"

According to ASHRAE Standard 62-1989, recommended fresh air flow rates have increased fourfold (from 5 cfm to 20-30 cfm per person). This means HVAC systems must handle larger volumes of outdoor air, bringing with it:

• Sensible Heat: High temperature from hot outdoor air
• Latent Heat: High humidity, particularly severe in tropical climates like Vietnam

In reality, latent heat accounts for 30-50% of the total cooling load of the system. When treating fresh air using traditional cooling methods (cooling coil), air is cooled below the dew point to condense moisture, then must be reheated to achieve the desired temperature. This process causes double energy waste: both cooling and reheating.

1.2. Sick Building Syndrome (SBS)

Research shows that indoor air pollutant concentrations can be 2-5 times higher than outdoors. When ventilation is inadequate, pollutants accumulate from:

• CO2 from human respiration
• Volatile Organic Compounds (VOCs) from building materials and furnishings
• Mold and bacteria developing due to high humidity
• Fine dust and suspended particles

The consequence is Sick Building Syndrome (SBS) with symptoms: eye, nose, throat irritation; headaches, dizziness; prolonged fatigue; reduced labor productivity.

2. Advanced TFA Technologies

To address these challenges, the HVAC industry has developed many advanced fresh air treatment technologies. Here are the three most optimal solutions today:

2.1. Energy Recovery Devices

Among energy recovery devices, the Enthalpy Wheel is evaluated as the most effective solution due to its ability to recover both sensible and latent heat.

Operating Principle:

The Enthalpy Wheel is a cylindrical rotor containing adsorbent material (usually silica gel or molecular sieve) arranged in a honeycomb structure. The rotor rotates slowly (2-20 rpm) between two air streams:

• Exhaust Air Stream: Conditioned air from indoors passes through half the rotor, transferring heat and moisture to the adsorbent material
• Fresh Air Stream: Outdoor air passes through the other half, receiving stored heat and moisture

Recovery Efficiency: Up to 70-85% depending on operating conditions, significantly reducing the load on the main cooling system.

Advantages of the new generation Enthalpy Wheel:

• Selective Adsorption: Using 3Å/4Å molecular sieve that only allows water molecules (2.8Å) to pass through, completely blocking bacteria, toxic gases, and odors
• Cross-Contamination Prevention (Purge Sector): Exhaust air purge zone before the rotor rotates to the fresh air side, reducing cross-contamination to <0.04%
• Non-contact seals: Increased lifespan and air tightness
• Low pressure drop: Saves fan energy

2.2. Desiccant Rotor Dehumidifier Technology

For applications requiring precise humidity control (low dew point), desiccant rotor dehumidifiers are the optimal solution replacing traditional cooling methods.

Why not use only cooling coils?

When cooling to dehumidify, air must be lowered below the dew point (usually 10-14°C). This leads to:

• Energy waste: Cooling deeper than necessary, then reheating
• Health risks: Wet cooling coils are ideal environments for mold and Legionella bacteria growth
• Humidity limitations: Difficult to achieve humidity below 50% RH at comfortable temperatures

Desiccant rotor mechanism:

Dezenno desiccant rotor dehumidifiers use a rotor wheel coated with desiccant material (silica gel or molecular sieve) rotating continuously through two zones:

1. Process Zone: Humid air passes through, water vapor is absorbed into the material, dry air exits
2. Reactivation Zone: Hot air (100-140°C) blows through, releasing absorbed water vapor outside

Advantages:

• Achieve very low dew points (-40°C to -70°C)
• Continuous operation, no defrosting required
• No CFC/HFC refrigerants used
• Precise humidity control ±3% RH
• Rotor lifespan 10-15 years

2.3. Integrated TFA Systems (Treated Fresh Air Units)

TFA (Treated Fresh Air Unit) systems are "all-in-one" solutions combining multiple technologies in a single device:

Typical TFA Configuration:

1. Air Filter: G4/F7/F9 depending on application
2. Enthalpy Wheel: Recover 70-80% energy
3. Cooling Coil: Deep cooling if needed
4. Desiccant Rotor: Precise humidity control
5. Heating Coil: Final temperature adjustment
6. Supply Fan: VFD for flow adjustment

Learn more: Dezenno.MAX Air Handling Unit (AHU)

3. Applications in Key Industries

Each industry has specific air quality requirements. Here are typical applications:

3.1. Pharmaceutical & Medical Industry

• Requirements: Humidity 35-45% RH, temperature 20-24°C, microbiological control
• Solution: Desiccant rotor + HEPA filter + Enthalpy wheel
• Benefits: Prevent raw material mold, ensure GMP, WHO-GMP standards
• Reference: DeAir Heat-Pump Dehumidifier for pharmaceutical production rooms

3.2. Electronics & Semiconductor Industry

• Requirements: Dew point -40°C to -60°C, Class 100-10000 cleanroom
• Solution: Molecular sieve desiccant rotor + Positive pressure AHU
• Benefits: Prevent static electricity, component oxidation, increase yield rate

3.3. Food & Agriculture Industry

• Requirements: Humidity 40-60% RH depending on product, temperature control
• Solution: TFA system combined with Heat-Pump dryer
• Benefits: Efficient drying, save 50% energy compared to electric resistance drying

3.4. Commercial Buildings & Hospitals

• Requirements: High IAQ, energy savings, 24/7 operation
• Solution: Dezenno.MAX AHU integrated with Enthalpy wheel + F7-F9 Filter
• Benefits: Reduce 40% electricity cost, prevent SBS, extend equipment lifespan

4. Infographic: Recommended Temperature-Humidity Parameters by Industry

5. Comprehensive Solutions from DeAir - Optimal for Engineers, Peace of Mind for Investors

With over 20 years of experience in temperature-humidity control, DeAir is proud to be a trusted partner of hundreds of businesses in Vietnam and the region. We provide comprehensive solutions from consultation, design to installation and maintenance.

5.1. Superior Technical Capability

• Expert Team: engineers with 20 years of experience working with leading brands like Bry-Air, Munters
• Precise Calculation: Using professional software to calculate thermal-humidity loads, optimal equipment selection
• ISO 9001:2015 Certification: Production and service processes meet international standards
• Manufacturing in Vietnam: Supply chain control, competitive pricing, rapid support

5.2. Core Product Lines

a) Dezenno Desiccant Rotor Dehumidifier

Manufactured according to European standards, suitable for low dew point applications (-40°C to -70°C):

• Air flow: 320 - 18,000 CMH
• VFD control, intelligent PLC
• Super-efficient adsorption rotor
• View details →

b) Dezenno.MAX AHU

Multi-function integrated air handling unit:

• Air flow: 1,000 - 100,000 CMH
• Static pressure up to 2,000 Pa
• Integrated enthalpy wheel, UL filters, AMCA fans
• High-strength aluminum profile frame, 25-50mm PU insulation
• Learn more →

c) DeAir Heat-Pump Dehumidifier

Superior energy-saving Heat-Pump technology:

• Capacity: 60 - 1,200 kg/day
• Save 40% electricity compared to conventional condensation dehumidifiers
• Stable operation at low temperatures (15-60°C)
• Explore products →

5.3. Representative Clients

DeAir has successfully implemented hundreds of projects in various sectors:

• Medical - Pharmaceutical: Cho Ray Hospital, Duoc Hau Giang, Enlie, Imexpharm
• Industrial Manufacturing: Samsung, LG, VinGroup, Sungroup, Taikisha, Kinden
• Textiles: May Duc Giang, May Ha Bac, May Phong Phu
• Logistics: KWE, CEVA, TBS

6. Frequently Asked Questions (FAQ)