Saving Water in Evaporatively Cooled Systems

Water is a limited resource, just like energy. Engineers are very aware of the need to save energy in their designs, and one of the best ways to do this is to take advantage of evaporative heat rejection for their cooling systems. The traditional cooling tower is an extremely effective way to reduce energy use at the compressors in a traditional cooling system. But introducing a cooling tower introduces a need for water to the system. It would be advantageous if this water use could be kept to an absolute minimum.

Especially since, in Seattle, water is expensive. As of this posting, the water utility rate per thousand gallons is $4.48 (summer) and the Sewer costs tack on an additional $9.96. When you consider that a cooling tower consumes a minimum of 1.8gph/ton (evaporation required to reject that heat), you can see that over a 1900 hour cooling season, these costs can really add up for a reasonably-sized cooling tower.



Earlier, I posted an article that highlighted ways to reduce water use in traditional cooling tower systems. For the most part, these recommendations address keeping the actual water use as close to the theoretical 1.8gph/ton evaporation figure as possible. Reducing the water use any further requires reducing the load on the tower, since evaporation is the only way a cooling tower can reject heat.

There are two ways to reduce load on a cooling tower--Reducing the total building load, or rejecting heat through some other method other than the cooling tower. Assuming the first option has already been exhausted through good engineering practices, the only other option is the second.

This is the approach taken by Aaon in their evaporative condenser systems. They essentially use a dry finned coil as the first stage of cooling before the refrigerant is cooled by evaporative methods. This essentially allows the system to reject as much heat as possible through a non-evaporative method before water is used. Every btuh that is rejected in this manner means less water used in the system.


This idea could be borrowed and applied to an open cooling tower by the use of a dry-cooler as a pre-cooler before a cooling tower. This way, the system rejects as much heat as possible in a dry fashion, and only uses water for what the dry-cooler can't do. This system gets to take advantage of the strengths of both methods of heat rejection--the water conserving function of a dry-cooler, and the lower water temperatures and more efficient heat rejection provided by a cooling tower.

Evapco has capitalized on this approach by creating a new, water-saving fluid cooler called the WDW:


This unit is a hybrid between a dry-cooler and an evaporative fluid cooler. It is provided with a control panel that controls both wet and dry sides of the unit, varying fan speeds with a VFD and determining when to run the evaporative pumps to optimize both water efficiency and fan energy.

Cutaway of an Evapco WDW unit

In practice, the evaporative system is only used for a small portion of the year, only when the design condenser water temperatures cannot be met by the dry-cooler side alone. What you see is a major reduction in water use compared to the same system served by a fully evaporative system:


Other advantages of this approach besides reduced water use are reduced chance of tower plume (since there are far fewer hours in which water is being evaporated, and when this does occur, it occurs in warmer temperatures) and the ability to provide some cooling even if city water is lost due to a service disruption.

But since a dry-cooler uses more fan energy per ton of cooling than a cooling tower, this system will inevitably use more energy to save water. Does this approach pay off?

An example from a real project might help demonstrate the economies involved. Below are the utility cost calculations from a project utilizing a 240 ton WDW installed in Seattle on a heat pump system with a portion of the load serving a 24/7 cooling application:



Note that even with the reduced water cost (to approximate the effective cost of using a deduct meter to avoid being charged wastewater charges for evaporated water) the hybrid system saves about 18% of the annual operational utility costs compared to a fully evaporative system. This affords a relatively quick payback for the added equipment costs associated with the hybrid system.

Adding Mechanical Cooling to Indirect/Direct Evaporative Systems

On this website, I have discussed indirect evaporative cooling, direct evaporative cooling and systems that combine the two into indirect/direct evaporative cooling. As we saw from the last article, however, there will likely be many applications where additional cooling beyond what can be attained by evaporative methods is necessary to keep a space comfortable. In these cases, we need to add mechanical cooling into the mix. But it is important to understand how to do this—there are tricks that can preserve most of the energy benefit of the evaporative cooling systems you have designed into your system.

The first trick is to determine where to put the mechanical cooling coil. The temptation might be to think it would be a mistake to put it in as the last component in the air flow. This is because it seems you would then simply be removing a lot of the latent effect that you are putting into the air in the direct evap portion of the system. However, inspection of psychrometric processes indicates that this is not the case. In fact, anytime the dew point of the air leaving the indirect evap is lower than the desired design air drybulb, you will see an advantage in running the direct evap section if it is located upstream of the cooling coil. A quick example will demonstrate this effect: Let's look at a 12,000 cfm system providing 60º supply air at an extreme sensible ambient weather condition in Seattle, WA. We will first look at this system with a standard mixed air (20% OA) arrangement with a traditional cooling coil. Then we will superimpose a three-stage indirect-mechanical cooling-direct system and compare the energy performance:

(click for larger image)

In the above image, the traditional mixed-air psychrometric process is indicated in red and the evaporative process in purple (with blue indicating the mechanical cooling portion). Both systems start at the ambient OA condition of 95º/68º. The standard cooling system then mixes the OA with return air in a 20%/80% proportion and then cools sensibly to a 60º leaving air temperature. (The cooling process in the traditional system is shown as purely sensible, but in reality, the system would likely use a return air bypass configuration to allow the portion of the supply air to be super-cooled to achieve latent cooling and thus prevent any latent load in the space from steadily building humidity through multiple passes through this pyschrometric process.) Note that the sensible cooling load in this system requires about 20 tons of mechanical cooling.

In the three-stage evaporative system, 100% OA is first indirectly cooled to to the condition at point I/D evap + R2. Then, mechanical cooling takes over to point I/D evap + R3, after which the direct evap section evaporatively cools to a 60º LAT condition at I/D evap + R4. I have then shown a sensible heating process from the LAT to represent the zone load to demonstrate that this will provide a very comfortable resultant air condition in the space at I/D evap + R5. Note that this is true even if there is a significant latent component to this load (The resultant room temperature is approximately centered in the pink zone that represents the ASHRAE summer comfort envelope). For this analysis, the direct evaporative system is operating at full capacity, and the cooling coil is modulating to provide the desired LAT DB. (Since this system is 100% OA, we are not concerned about humidity levels building up in the space as in the recirculating system.)

The first thing that should just jump out of this is that the evaporative system requires less than HALF the mechanical cooling of the traditional system--while providing the increased ventilation benefit of 100% OA! And this is neglecting the additional latent cooling load that would probably be needed to maintain humidity levels in the space with the traditional recirculating system. To add to the IEQ benefit, the direct evap section works as an air washer and effectively increases the filtration of the air to improve IEQ beyond that of a traditional 100% OA system.

Now lets compare the three-stage system we just examined (with a indirect/cooling coil/direct arrangement) to that of a three-stage system with an indirect/direct/cooling coil configuration:

(click for larger image)

Two things should be obvious in this example. First, the mechanical cooling load is even lower than in the previous example: down to under 5 tons! Thats about a quarter of the load for the traditional system, and a little more than half of the load of the evaporative system with the cooling coil before the evap section. Second, and this is the secret behind the reduction in mechanical load, the air leaving this system is significantly closer to saturation than the previous example. In other words, despite the fact the leaving dry bulb temperatures are the same in both cases, in the latter case there is more latent heat in the supply air. The evaporative cooling process before the coil allows the system air to hold more latent energy but yield the same sensible condition for conditioning the space. A quick inspection of the comfort zone indicates this air is perfectly suitable to provide an acceptable comfort condition, even with a reasonable latent load.

Earlier, I said there should be an advantage to running the direct evap upstream of the cooling coil if the dew point of the air entering the direct evap was colder than the design air DB. In this case the dew point of the entering air is 53 degrees--which is quite a bit cooler than the 60 degree design point we are looking for, so thus we gain the advantage seen. What about the case where the entering air is too moist? Let's look at a system where the entering air dew point is well above the supply air temperature:

(click for larger image)

In this case, the OA enters with a 62º dew point. It cools through an indirect section to about 72º/65º, and then directly to a cooling coil to reach the leaving air temperature of 60ºF db. Since the enthalpy and WB lines are nearly parallel, it seems there is very little advantage to using direct evaporation to get the air leaving the indirect evap section to saturation and then cooling it. But, importantly, there is certainly no disadvantage, (other than the electrical draw of the pump). Also notice that again, this system provides a significant load reduction compared to a standard system even while providing 100% OA!

Running through that process actually shows a slight advantage for using the direct evap section:

(click for larger image)

This cooling advantage should be confirmed for your specific system since it is highly dependent on the latent capacity of the cooling coil, and is offset by the pump energy and some small increase in system static pressure when the direct evap media is wet.

However, keeping the direct evap pump running even in these conditions provides several advantages besides energy savings:

• Simplifies the control scheme
• Provides IEQ benefit of air washing
• Increases the life of the direct evap media by reducing cycling of the evap pump

Whether or not it makes sense to use the direct evap portion of your system in times of high ambient moisture is a decision that can change depending on the particulars on any given project. But if there is a net energy penalty for using this system when the OA dew point is high, one can see from this analysis that the penalty is slight and that it would only occur for very few hours a year.

Saving Water With Evaporative Condensing

Using evaporative cooling makes energy sense, not just in directly cooling the air, but also in cooling the heat rejection portion of a compressorized cooling system. This is because refrigerant compressors can be thought of, simplistically, as pumps. In a pump, two things govern energy use--the flow rate of fluid through the pump, and the head that pump needs to overcome to move the water. The same is essentially true for compressors.

In a compressor, the mass flow rate of the refrigerant essentially determines the cooling capacity it is providing. So for a given cooling load, we can't reduce the flow rate to increase our efficiency. All that is left is the compressor head. And that is something that we can effect.

In a refrigerant system, the condensing pressure of the refrigerant vapor is determined by the temperature of that refrigerant.

Let's look at this relationship for R-410a (from DuPont .pdf here):




We can see that the condensing pressure for 120º R-410a (which is around where an air-cooled condenser would operate) is about 450 psi. Compare that to a condensing pressure of about 280 psi or so at a temperature of 90º-which is an easily attainable condensing temperature in an evaporative condenser in the Pacific Northwest. When you consider that a reasonable suction temperature might be about 42º (or 150 psi) reducing your condensing temperature from 120º to 90º represents a head reduction of nearly 60%! In practice, moving to an evaporatively condensed piece of equipment from a comparable air-cooled piece of equipment can improve NPLV's by about 20% or so.

So, obviously, this makes sense from an energy conservation point of view. But what about water use? The obvious trade-off is that you are now using water where before, in the air-cooled case, you weren't. So how can we reduce the use of water while still benefitting from the reduced head pressure on the compressors?

To understand how how to improve water utilization in these systems, it is important to know what the state of the industry is for evaporative condensing. A typical system is illustrated below:


What you typically have is an induced draft evaporative unit that sprays water over a refrigerant coil. The water evaporates, and that evaporation cools the refrigerant in the coil. The remaining water falls into a basin where a pump then sprays the water back up over the coil again. All the while, a fan operates to draw air past the water and enhance the evaporative process. Importantly, every 1000 btu rejected by this system reflects about pound of water evaporated.

So what can we do to reduce water use? Well, the obvious thing is to reject less heat via evaporation. However, this might seem problematic because we want to maintain the low condensing temperatures that we can reach using evaporation. This is where it is important to understand a little about how refrigerant systems really work.

One of the main concerns with refrigerant compressors is they are designed to move gas--not liquid. A very effective way to break a compressor is to introduce liquid into it. So to be sure that no liquid enters the compressor, refrigeration systems are designe to operate with a few degrees of superheat. This takes the refrigerant safely away from the saturation line, and assures that the compressor will not see any liquid. However, this adds some extra heat into the system that then need to be rejected. Then, through the operation of the compressor, even more heat is added into the system, taking the system even further away from saturation.

However, the additive effect of the intentional pre-compressor superheat and the heat added by the compressor itself means that there is a significant amount of heat in the refrigerant that needs to be rejected before refrigerant condensing can even start. This de-superheat process is illustrated below:

(click for larger image)

If this heat can be removed without requiring evaporation, a significant amount of the water use can be eliminated. And this is exactly the approach that Aaon has taked with their evaporative condensing design. Their solution is illustrated below:



The main difference between the first system and this one is the addition of a finned desuperheater coil located above the spray system, in the cool, saturated air stream above the wetted portion of the condenser. This coil allow the system to reject the superheat without using any water--saving, on average, about 20% of the water use at peak load.

However, the benefits extend beyond there, since at about 70º ambient, this coil can reject about 50% of the total heat in the system, and it can reject 100% at about 30º ambient. So the true water savings range from about 20% to 100% depending on the operating profile and ambient conditions of the unit.

There are still other benefits: If chemical water treatment is being used on this system, the lower water use will translate to lower chemical use. And, since the tube surfaces in the wetted portions are at lower temperature in the Aaon system, there is a corresponding lower chance of creating scale--which is formed primarily from calcium carbonate which exhibits inverse solubility, depositing much more readily at higher temperatures. This lower fouling, in turn means the system will operated more efficiently for years to come, since less scale means better heat transfer at the tube surfaces which means lower head pressure on the compressor!

Introduction to Indirect-Direct Evaporative Cooling

Now that we have covered the basics of the indirect and direct evaporative cooling processes, it's time to consider one more wrinkle--putting them together.

In the IDEC cooling discussion, I made the point that not only do we get a reduction in dry-bulb temperature as our airflow passes through the IDEC unit, but we get a reduction in wet-bulb temperature, also. And since we now have seen that the direct evaporative cooling process depends critically on the wet-bulb temperature of the air it is cooling, it seems we should get some advantage by running the air through the IDEC section, and then running it through the direct section. And we do:

(click for larger image)

As you can see, the resultant leaving dry bulb is on the order of 64º, which is better than the resultant of 72º from the indirect section alone, or 69º for the direct evaporative section alone. Now 64º degrees may not seem cool enough for typical cooling applications--and for most projects it probably isn't (although it is important to not that ASHRAE comfort conditions can be met with this leaving air condition in a predominantly sensible load application given enough air). But keep in mind that this is the performance on a design day. How many hours a year would you be able to meet the traditional supply air temperature of 55º? Lets look at psychrometric chart with Seattle bin data loaded into it:

(click for larger image)

A quick note of explanation: The vertical line at 55º is the economizer line--any climactic conditions to the left of that line can be used to create cooling air directly using OA alone (or mixing OA with RA) and thus require no additional cooling at all. The blue diagonal line along the 53º wet-bulb line is a conservative mapping of the direct evaporative regime. At any bin hours under this line, direct evaporative cooling can be applied to the ambient OA to achieve cooling air directly. And lastly, the red diagonal line above that is the indirect-direct evaporative cooling regime, where the application of both cooling techniques will provide acceptable supply air conditions (assuming about 70% effectiveness on the IDEC). And above that line, the indirect evaporative system can still be applied to greatly reduce the load on any supplemental mechanical cooling system, if used to meet the same 55º leaving air condition.

Two things jump out of this analysis: First, the vast majority of the hours are satisfied without using mechanical cooling. In fact, in Seattle, most hours are met with simple economizers--which explains the emphasis in our local codes on this cooling technology. You can even think of evaporative cooling as simply an enhancement to the standard economizer. The second takeaway is that there are still quite a few hours that are not met. How can we address this?

Well, one way is to play around with the leaving air temperature. If we supply some more air to the zone, we can provide warmer cooling air. Let's look at that same chart, only this time lets use a supply air temperature of 60º:

(click for larger image)

By simply providing for a little more air to the zone, we meet a much higher percentage of the bin hours; so much so you that can now consider a system without mechanical cooling, as long as the occupants are willing to accept a few more hours outside of standard comfort conditions a year. Granted, this additional comfort comes at an energy cost--the cost of moving that additional quantity of air. This cost is, of course, offset by the avoidance of mechanical cooling. But, additionally, we know from the previous chart that this additional air is not needed all of the time. A variable speed control on the fans would naturally bring the air volumes down during periods where colder air is achievable.

One of the things that should be obvious is that this analysis is greatly dependent on the local climate and elevation of the project. To evaluate how effective this cooling method is, you need to create similar plots for each project locale. And where you are in the state has a great effect on how well you do. For example, a cool-wet climate like that on the Olympic Peninsula sounds like it might be a good candidate. So let's see how it compares to Seattle:

(click for larger image)

It looks pretty similar to Seattle, as we might guess. How about a hot, dry climate like Spokane?:

(click for larger image)

That's a real winner! There's only a small fringe of hours outside of the range where indirect/direct evap works alone. So if Spokane works, surely Yakima must also be a great candidate:

(click for larger image)

Hmmm... There's quite a few hours outside of the indirect/direct evap zone. Good thing we did this analysis before committing to a evaporative-only system!

Indirect-direct evaporative cooling, either as the main cooling technology or as an enhancement to the economizer cycle is a technology that has wide application in the Pacific Northwest, even in rainy Seattle. But it is a technology that requires careful analysis--it's not as simple as throwing compressor tons at a cooling problem. With today's emphasis on energy efficiency and sustainability, it is a technology that deserves a second look.

There is certainly more to talk about on the subject. Future topics will include integrating compressorized cooling with an evaporative system, indoor comfort conditions, water treatment and maintenance, control of evaporative systems. and the role of return air in these systems.

Resources you may find useful:

Energy Labs Indirect/Direct System Performance Calculator (Simply the direct and indirect calculators linked together
Energy Labs Direct/Indirect Evaporative Systems Engineering Guide (booklet format)

Introduction to Direct Evaporative Cooling

Now that we have discussed Indirect evaporative cooling, let's move on to the next question: What is direct evaporative cooling?

Direct Evaporative Cooling is a process where air is sensibly cooled by the effect of the evaporation of water directly into the delivered air stream. This is typically accomplished by use of a wetted absorbent media in the air stream, most commonly Munters CelDek (pdf) or GlasDek (pdf).

Evaporative media in an Energy Labs Unit

This process has the advantage over IDEC systems in being much more efficient (with efficiencies in the range of 90% easily attainable), but with one major difference: Direct Evaporative cooling is an adiabatic process. This means that there is no energy added to or removed from the airstream. The enthalpy of the air is unchanged, even as the sensible temperature is cooled.

How is this possible? Well, essentially you trade sensible heat for latent heat. As you reduce the dry-bulb temperature of the air, you concurrently increase the humidity ratio of the air. What you lose in sensible heat, you make up in the heat embodied in the evaporative phase-change of the water.

What does this look like on a psychrometric chart? Take that Seattle design day* of 85º/67º db/wb. Let's bring in 22,000 CFM of 100% OA. If we select a direct evaporative system with an 89% efficiency, the leaving air temperature will be about 69º/67º. Note that the wet bulb is essentially unchanged. The chart of this process is below:

(click for larger image)

Essentially, for this service, you get about 32 tons of sensible cooling but and zero tons of total cooling. If you were to allow this supply air to warm sensibly to a room temperature of 75º, you would find that the space RH would be close to 70%, which would probably not be acceptable for standard comfort cooling applications. However, in high-sensible cooling applications, like, say, data centers, this method of cooling has great application.

Additionally, since the resultant indoor conditions depend greatly on the outdoor air conditions, Direct evaporative cooling can provide acceptable air conditions for much of the year in a cool, dry climate like Seattle. In fact, any time the ambient wet bulb temperature is 53º or less, the direct evaporative cooling can provide supply air almost identical to that off of a 55º cooling coil, with pressure drops at the media on the order of half that of a standard cooling coil! Direct evaporative cooling can used to essentially greatly extend the hours of economizer performance available on almost any cooling system.

But the benefits do not end there--because pre-cooling with direct evap systems upstream of a cooling coil can significantly decrease energy costs for sufficiently dry ambient conditions:



Resources you may find useful:
Energy Labs direct evaporative performance calculator
Energy Labs Direct/Indirect Evaporative Systems Engineering Guide (booklet format)


*Note: When applying evaporative systems, often it is necessary to consider the performance of the system at the ASHRAE evaporative design day conditions, in addition to the sensible design day conditions that we commonly use. And, additionally, it can use what would normally be unwanted space heat in the return air to provide beneficial humidification in times of low humidity.

Introduction to Indirect Evaporative Cooling

What is indirect evaporative cooling?

Indirect Evaporative Cooling (IDEC) is a process where air is sensibly cooled by the effect of the evaporation of water across a heat exchanger. The advantage being that for most climactic conditions, there is a significant difference between the wet-bulb and the dry bulb temperatures at design conditions. This 'wet-bulb depression' allows the designer using indirect evaporative cooling to create supply air temperatures below the ambient dry-bulb temperature without using any refrigeration at all.

Take a Seattle design day of 85º/67º db/wb. If we bring in 100% OA (which is pretty common for IDEC systems) we will have, obviously, an OA condition of 85º/67º. If we have indoor air to exhaust and use as a heat sink in a traditional, dry air-to-air heat exchanger, we will have about 75º air to use to cool down the 85º OA. Assuming about a 70% efficiency for this type of heat exchanger, that means we can realistically drop the OA by about 70% of the difference from 85º to 75º or about 7 degrees. We should be able to get a resulting LAT from the HX of 78º. Note, however, that we will need some sort of refrigeration in our system to create the indoor environment of 75º from which we are taking conditioned air to cool the OA.

Now let's consider an IDEC system for the same service. This sort of system can take on many forms, including the exact same configuration as noted above, simply with the addition of a direct-evaporative media section in the exhaust air upstream of the air-to-air heat exchanger above. For this comparison, however, let's use a built-up Energy Labs IDEC system. This is essentially a closed-loop fluid cooler for air. An induced draft fan pulls OA upwards past water spray to encourage evaporation and the supply air is cooled across an internal heat exchanger without contacting the water.

Energy Labs IDEC Module

To make this realistic, let's give this service an actual CFM and pick a particular IDEC model. Let's say this is a 22K cfm service and let's pick the nominal I-220-48 IDEC unit. With 85º/67º OA conditions*, the effective temperature difference across the heat exchanger is not 10º (OA db of 85º-EA db of 75º) but actually 18º (OA db of 85º - OA WB of 67º). Note we did two things, we increased the overall temperature difference the heat exchanger sees, and we eliminated the need to have an available exhaust air stream exhausting pre-cooled air. Checking the performance of this particular IDEC unit, we see that it has an overall effectiveness of 69% at these conditions, and the LAT from this system is 72.5º/63.2. That's a 5.5 degree improvement in LAT, or, for this supply air quantity, nearly 11 additional tons of cooling. And we don't need to have any mechanical cooling anywhere in the building to achieve this leaving air condition.

Let's examine this cooling effect on a psychrometric chart:

(click for large image)

The first thing you should notice is that the cooling process is purely sensible--no humidification or dehumidification is performed. The other thing you should note is that the supply air wet bulb temperature is a few degrees cooler than the OA wet bulb temperature, 63º vs. 67º. This is of critical importance when applying direct evaporative cooling to these systems in an indirect/direct hybrid system.

In the end, however, you can see that about 25 tons of cooling was provided, at a mechanical cost of about 1" of static pressure drop and the operation of 3 3/4 HP of fan and pump energy for the IDEC unit.

This is very inexpensive and sustainable cooling. Of course, the delivery temperature is higher than typical for standard air-conditioning applications, but if viewed as a first stage of a multi-stage system, you can see that there is a compelling case to be made for using this sort of technology to at least partially offset cooling loads that would traditionally require compressorized cooling, and greatly expand the hours of available economizer function.

Resources you may find useful:
Energy Labs IDEC performance calculator
Energy Labs Direct/Indirect Evaporative Systems Engineering Guide (booklet format)

*Note: When applying evaporative systems, often it is necessary to consider the performance of the system at the ASHRAE evaporative design day conditions, in addition to the sensible design day conditions that we commonly use.

Evapco ESWA: The Most Efficient Fluid Cooler on the Market

Recently, Evapco introduced a new fluid cooler design that blows away other traditional units in efficiency and sound performance.

The secret? They re-thought how to design a fluid cooler.

In their testing, they found that the most efficient heat transfer occurred in a fluid cooler coil when the coil was completely flooded with water. However, in a traditional fluid cooler design, this condition could not be attained because air flow was needed over the coil in order to evaporate a portion of the spray water pouring over it.

Traditional Fluid Cooler Design

A little out-of-the box thinking led their engineers to realize that there were two heat transfer processes that really mattered in a fluid cooler:

1. The spray water cooling the fluid in the coil by conduction
2. The air cooling the spray water water by evaporation

Both of these processes were optimized in different conditions. So they decided to separate the two processes from each other:

New ESWA Design

The new ESWA cools the spray water with conventional cooling tower fill and then, only after the water is cool, floods the coil for optimal heat transfer.

The result? A fluid cooler that uses 30%-50% less energy than a traditional induced draft cooler, and up to 80% less than a forced draft tower!

And there are other benefits, too. Since the water basin is completely enclosed, the splash noise from the basin is attenuated, making the ESWA one of the quietest fluid coolers on the market. The basin is also accessible, making the ESWA coil extremely easy to inspect and clean. And since the air inlets are above the coil, very little 'stack' effect is created, making the heat loss from a standard ESWA in heating season less than that of a traditional fluid cooler equipped with positive closure dampers!

Evapco Hits the Big Time

Funny things happen when you type "Evapco" in to the search box at Youtube:



No, I don't understand it either

Best Practices for Data Center Design

A 2006 study published by Lawrence Berkley National Laboratory, Environmental Energies Technologies Division examines best practices for energy-efficient data center design. Some of the best practices highlighted include well-understood and accepted practices like ‘right-sizing’ central plants and using hot and cold aisles. However, the article makes a strong case for the use of air-side economizers for the minimization of energy-using refrigeration and direct evaporative cooling for humidification. Read more here:

Best Practices for Data Centers: Lessons Learned from Benchmarking 22 Data Centers

Cool Ways to Conserve Water

A few years back, I had an article published in the April 2005 issue of Plumbing Systems and Design Magazine that highlighted the many ways to optimize the water saving performance Cooling towers.



You can read that article right here.