humid climate design - airah · 2017-03-22 · manufacturing storage ... the taj mahal - india ......

Humid Climate DesignPresented by:

George Strohmeier, M.AIRAH, Carel

Adiabatic Humidifiers

Adiabatic humidification

Evaporative cooling


Why Humidify

There are 3 basic questions that determine why an environment needs to be humidified.

Why HumidifyThe first two questions cover mainly processes.

1. Hydroscopic materials involved?

2. Static electricity involved?


These are the 4 main points: Manufacturing Storage Preservation Safety

The 3rd question is about humans

3. Health and comfort considerations?

Health – reduces illness Comfort – well being Productivity – Indoor Air Quality

Adiabatic HumidifiersWhy Humidify

Atomising AppliancesOutput

CapacityPower

consumption Droplet size

kg/h W/kg/h µm

Adiabatic washer (duct only) 10 - >1000 6 - 7 200 µm - 2 mm

Centrifugal humidifiers (duct application) <20 - 200 3 - 5 > 30

Centrifugal humidifiers with fan (room application) < 6.5 20 - 30 6 - 8

Pressurised water (duct & room application) <20 - 1000 4 - 7 10 - 20

Compresses air (duct & room application) <20 - 250 70 - 110 5 - 10

Ultrasonic (duct application) 1 - 20 50 - 60 3 - 5

Ultrasonic with fan (room application) 0.5 - 10 80 - 100 3 - 5


Adiabatic washer


Pressurised water humidifier

Room application Duct application


Compressed air humidifier



Ultrasonic humidifier



Evaporative AppliancesOutput Capacity Power

consumption

kg/h W/kg/h

Rotating drum (duct application) <10 10 - 15

Rotating drum with fan (room application) <2 10 - 30

Wetted media with recirculation (duct application) 10 - 1000 0.5 - 1

Wetted media without recirculation (duct application) 10 - 1000 ~ 0


Rotating drum humidifier


Wetted media humidifier

With recirculation Without recirculation


Isothermal humidifiersOutput

CapacityPower

consumption

kg/h W/kg/h

Immersed electrodes 1.6 - 130 750

Immersed elements 2 - 80 750

Gas fired 45 - 180 300 el / 750 gas


One product – two goals!

• Humidification• Adiabatic cooling

100 L/h Water atomised equals 70 KW mechanical cooling

= Latent heat of vaporisation


The total surface area of 1 litre of water atomised into droplets with an average diameter of 10 µm is 600 m².

The larger the water surface, the quicker the water evaporates when in contact with air. The evaporation rate is “proportional” to the contact surface air – water.

How Quickly Does Water Evaporate


History

The cooling effect of adiabatic cooling was known way back in time.

Two classical examples are: The Taj Mahal - India Herodot’s safe house in Masada - Israel


Advantages of evaporative cooling

Substantial Energy savings possible Reduces mechanical cooling Reduces CFC/HCFC/HFC use Reduces CO2 foot print Reduces electrical peak demand Provides humidification when needed


Design of AHU systems• Adiabatic humidifiers applications require

more engineering than steam humidifiers.One receives a tailored solution!

• Depending on the application a pre-heater and/or post-heater is required.

• If indirect cooling is applied the adiabatic humidifier is located in the RA.


Direct humidification & cooling (duct)Heat recovery sectionCross flow heat exchanger


Indirect cooling (RA duct)


Cooling in RA and Cooling & humidification in SA


Cross Flow Thermal Wheel Run around coil

HygienicGood efficiencyNo moving parts

Low hygieneHigh efficiencyMin SpaceMoving parts

Good hygieneLow efficiencyMoving parts


Applications

Duct and Room humidification / cooling is best with the new generation of adiabatic humidifiers – pressurised water humidifiers.

Ultrasonic and compressed air humidifiers do not have the same overall flexibilities, but can be applied in a similar fashion.


Direct room humidification / cooling


Large room systems Small room systems

Single AHU (duct) humidification

1 – drop pan (mandatory)

2 – drop separator (mandatory)


Water treatmentMost adiabatic humidifiers require treated water. The nature and extent of the treatment used depends on the properties of the water and the type of application.

The dissolved minerals in the water fall out as white dust when the water evaporates which is a very unpleasant result.

All these problems can be overcome by demineralising the water with an RO system.


Water treatment – isothermal humidifier

The element type models profit by treating the water with an RO system.

The dissolved minerals in the water remain as a deposit in the cylinders when the water is steamed off. The removal requires a maintenance call. Treated water does not contain these minerals any more and the maintenance is therefore reduced to one per annum instead of several!


Maintenance

All humidifiers require maintenance!The level of maintenance varies with the humidifier technology used.

Pressurised water humidifiers require very little maintenance. Some of them have wash cycles which leads to hygiene certifications.


Economic analysis of the humidification process

Choice between adiabatic and isothermal humidification

This depends not only on the specific requirements of the installation, but also on energy evaluations. Therefore it depends essentially on functional and economic observations.

When humidification & cooling is required – adiabatic humidification is the most convenient option.

When there is a need for heating and humidification, as is the case with Air Conditioning during winter, the isothermal humidification is favoured. Adiabatic humidification here does not offer any advantages in energy terms.


Energy balance of the humidification process

The frequent belief that adiabatic humidification occurs with a minimal contribution of thermal energy is incorrect.The difference compared to the isothermal process simply involves the method used to provide the heat required to absorb the moisture.

The change of state is the latent heat of vaporisation


Conclusion

Modern adiabatic humidifiers are designed to maximise humidification efficiency and minimise water wastage.

Modern adiabatic humidifier offer low running costs for large humidification loads – along with the benefits of free cooling.


Energy Saving by DEC/IEC: ROIsAdiabatic Humidifiers

Thank you

humid climate design - airah · 2017-03-22 · manufacturing storage ... the taj mahal - india ......

Documents