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Condair ‘Brand Leader’ Interview Podcast 1 – Transcript to Support Learning
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‘Exploring The Evaporative Cooling Opportunity For HVAC System Specifiers’
Condair ‘Brand Leader’ Interview podcast – Transcript to support learning
Every effort has been made to flawlessly transcribe the interview to support learning but please consider the recorded audio of the interview as the actual source of information for learning purposes.
Hi this is Mick de Leiburne for BusinessNet Explorer and welcome to a special edition of our ‘Brand Leader’ interview series.
Well, Evaporative Cooling is not a new Air Conditioning technique. Its use can be traced all the way back – to ancient Egyptians – wafting air over water filled pots. However, its popularity for providing high capacity, low energy cooling has recently exploded, largely due to its use in modern data centres.
Today we are joined by Dave Marshall-George, Sales Director at humidity control specialist, Condair, to look at how humidifiers can be used in Air Handling Units to take advantage of this energy and cost efficient cooling strategy.
Dave joins us on the phone….Hi Dave thank you for joining us today on the BNE Product News podcast for the Construction & Building Services industry
Hi Mick and thank you for inviting me to explore the Evaporative Cooling opportunity for HVAC system specifiers
So Dave, let’s start initially with the science – could you talk us through the physics of Evaporative Cooling?
The physics of evaporative, or adiabatic cooling, as it is sometimes referred to, is based around a transfer of energy. As water transforms from its liquid state into a gaseous state, it consumes energy. And this energy is taken from the air, in the form of heat or thermal energy.
In order to evaporate one kilo of water at 15°C, around 680W of thermal energy is used. Which means that for every kilo of water evaporated into an atmosphere, 680W of evaporative cooling is achieved.
Now for a mechanical cooler to deliver 680W of cooling, it would consume around 220W of electrical energy. However, it’s possible for a single evaporative humidifier to deliver over 1,000kg of moisture and a resulting 680kW of cooling, while still operating on less than half a kW of electrical energy. Amazingly that’s over 500 times the cooling delivered from a mechanical cooling system, from a very similar amount of electrical energy.
But, the potential to use evaporative cooling is limited by how much moisture the air can absorb – and this comes down to its relative humidity. If the air is already very humid, evaporative cooling’s effect is limited. But not necessarily eliminated, as some AHU strategies will still greatly benefit from evaporative cooling even in very humid climates.
What are the main strategies for using Evaporative Cooling in Air Handling Units?
There are three. Direct evaporative cooling, In-direct evaporative cooling and another form of In-direct, which we call Exhaust air in-direct.
Now the first is quite simple. Direct evaporative cooling. The AHU brings in fresh outside air, it passes it through an adiabatic humidifier where it absorbs moisture and is cooled. This then cooled air is supplied into the indoor environment. A percentage of the indoor air is continually vented outside, thus allowing more cooled, fresh air in.
This strategy is ideal for warm dry climates and buildings that can have high levels of ventilation. However, its not so useful in very humid environments, as the evaporation of the water from the humidifier depends greatly on the incoming air being able to absorb it.
The second strategy is in-direct. The air handling unit in this strategy is operating with two airstreams. One that draws cool outside air into the AHU, and then passes it through a heat exchanger before venting it outside. Whilst the other air stream extracts warm air from the building, passes it through the same heat exchanger and then reintroduces it into the building. Neither airstream physically mixes, but the colder outside airstream is used to cool the warmer internal airstream via the heat exchanger.
Now this can cool a building even without evaporative cooling, but if you apply a humidifier to the external airstream prior to the heat exchanger, you can reduce the temperature of that external airstream and get even more cooling from the system. It does however, rely on the outside air being colder than the inside air, either before or after humidification. So again, in a very hot and humid climate, this may not be the most effective strategy.
However, in temperate climates, this strategy is ideal for data centres or other secure buildings, as it reduces the risk of introducing pollutants to a building from outside. It should be noted however, that this isn’t a ventilation system, so fresh air will still need to be introduced by some other method.
The third strategy is exhaust air in-direct. This method also uses a heat exchanger. Warm air is extracted from the room and passed through a humidifier, where it saturates as close to 100%RH as possible. This cools the air as much as possible before it’s passed through the heat exchanger and subsequently vented outside. Another airstream draws fresh air in from outside and passes it through the heat exchanger, where it is cooled by the humidified and exhausted room air.
The heat exchange can reduce the temperature of the incoming air by a few degrees, which doesn’t replace the need for mechanical cooling but can significantly reduce the requirement for it. This strategy can also be used in hot and humid regions, as the room air that the humidifier is cooling is always dry enough to be able to absorb moisture.
You have a new Webinar on this subject where one of the key benefits highlighted is Energy Savings. Could you describe one of the case studies presented in the Webinar and explain when and how – the Energy Savings are achieved?
Yes. Our webinar on the 29th September explains the psychrometrics of evaporative cooling, details each strategy and uses real life case studies to illustrate their potential. One such case study is a client we work with in the telecommunication sector. They were needing to replace mechanical cooling systems in rooms that suffered high heat gain from electronic equipment.
They developed an air handling unit that uses a direct evaporative cooling strategy. Rather than using mechanical chillers to cool the room, they brought in outside air and vented the internal air. During the winter, it can run in free cooling mode without any need for evaporative cooling, but when the outside temperature rises to around 20°C, the evaporative cooler switches on and increases the cooling capacity. This allows the AHU to successfully achieve the indoor target condition without ever needing mechanical cooling.
In total the new AHU strategy reduced the electrical energy consumption of the cooling system by an amazing 80% in comparison to the previous mechanical system.
The opportunity for the HVAC industry is clearly exciting – how can our listeners learn more – about Evaporative Cooling – and its benefits?
Alongside the webinar we have coming up, Condair also offers training on this topic in the form of a CIBSE approved CPD. We can offer these 1 hour training sessions either online or in-person. Anyone can request one from our website at www.Condair.co.uk.
In fact, our website has a lot of information, downloads and case studies on this topic for anyone wanting to learn more. It’s a great place to start. It was Condair.co.uk.
Another online resource is a Condair website called MyCoolBlue.com. That’s MyCoolBlue.com. The website uses historical weather data from over 300 locations around the world to accurately calculate how much cooling can be provided via evaporative, free air and mechanical systems for any exhaust air indirect cooling project. Simply input the parameters of the AHU and the desired indoor conditions, and the system will project the cooling capacity that can be delivered across the three different methods.
And lastly, I’d suggest if anyone wants to learn more, simply contact Condair. Our experienced sales team is always happy to talk to consultants, contractors or AHU companies about the potential savings AHU evaporative coolers can offer.
That’s great and we’ll include the link for the Webinar in the description for this podcast for our listeners. Well, Dave thank you again for joining us today on this special edition BNE Product News ‘Brand Leader’ interview podcast discussing why including Evaporative Cooling is such an exciting option to explore when considering ‘state of the art’ best practice in Air Conditioning in a variety of applications.
Thank you for inviting me Mick. I’ve enjoyed exploring the subject with you. GoodBye.
That’s a pleasure. Cheers.
For more information about Condair please go to www.condair.co.uk
