Since the dry cooler uses only air as the cooling carrier, this industrial system can structurally achieve output temperatures no lower than the air’s dry bulb temperature (i.e., the temperature of the outside air): this is something to always keep in mind in order to know whether this is the solution we need. The consequence of this is that the dry cooler becomes the optimal solution if it is sufficient to obtain a medium to high temperature fluid output, especially if we think about the warmer seasons and if we do not want to use water as a cooling “tool”.
CHT TECK Product Page
So how to size a dry cooler correctly? How to correctly calculate the required capacity? Several factors come into play.
It is critical to select a dry cooler with the appropriate air flow rate and heat transfer surface area for the amount of heat to be dissipated by the fluid. Factors such as the temperature and volumetric flow of the process fluid, the ambient temperature, and the desired temperature difference at the outlet play a key role in sizing the dry cooler.
We have also seen that dry coolers are able to lower the temperature of the process fluid close to the ambient air temperature.
Sizing a dry cooler is a process that requires careful evaluation of several factors to ensure that the selected unit will meet the specific needs of the application.
The main steps are as follows.
In addition to these elements, others must be taken into account in order to correctly size and calculate the required power of a dry cooler: available space, noise levels required for proper operation (considering the civil or industrial context of the installation), needs related to future maintenance of the system…
The variables, as can be seen, are many. As in any case, a good process cooling advisor is, however, able to orient the client by asking the right questions about his or her needs. There is also specific software that, considering application parameters, helps the professional simulate its performance in terms of fluid outlet temperature and define the most suitable dry cooler model.
Dry coolers are certainly not the only systems for heat dissipation in industrial processes.
The question of what is the best cooling system to use to cool fluids (water and glycol or other fluids) for use in manufacturing processes is a great classic. Manufacturers and consultants typically respond with another classic answer: it depends. Because the best cooling system does not exist and instead one must know and compare the different structural advantages of chillers, evaporative cooling towers, adiabatic dry coolers, and “standard” dry coolers.
Again, we then make a comparison on how dry coolers work compared to other heat dissipation systems.
Here is a classic example of contrasting different cooling systems: better a dry cooler or an industrial chiller?
If you are looking for more details, kindly visit Custom Cooling Systems Manufacturers.
It is clear that we must start with the output temperatures allowed by the two systems. In this sense, a chiller (“mechanical cooler”) can achieve output fluid temperatures well below room temperature, even below 0 °C. A dry cooler, on the other hand, is more suitable, as we have already seen, for medium to high output temperatures (in warmer seasons) or at least close to those of the outside air. It is in fact a system that cannot structurally go below the dry bulb temperature of the environment.
But what if the demand is for intermediate outlet temperatures, for example, between 20 and 30 °C? In this case, more attention must be paid to the other design factors and needs of the system to be served.
A further point to be made is about the structure and components of the two systems. An air cooler is a simple piece of machinery, consisting essentially of a heat exchange coil and a motor-fan assembly. On the other hand, a chiller or refrigeration unit is a much more complex system that must leverage an entire refrigerant circuit to achieve its high performance.Such a solution generates much higher acquisition and operating costs and requires more maintenance.
To optimize energy use and provide flexibility, it is still possible to combine dry cooler and chiller-a solution that has seen some growth in recent years. For example, one can use the dry cooler during colder times of the year and the chiller during warmer periods, or use the dry cooler as a pre-cooler to reduce the load on the chiller. Not to mention that there are so-called free-cooling chillers, which function as dry coolers during cold periods, allowing compressors to be turned off and saving energy.
For your convenience, here is a useful and necessarily simplified primer on the most important factors to consider in evaluating an informed choice: dry cooler vs. chiller.
In terms of operating result, the main difference between a dry cooler and an evaporative cooling tower lies in the fact that the former has in the dry bulb temperature of the air (the outside air temperature) the minimum limit for the output temperature of the cooled fluid. In contrast, the cooling tower can get close to the wet bulb temperature (approximately 10 °C below the outdoor temperature).
There is a precise formula for calculating the wet bulb temperature (Tw) given the dry bulb (Ta), as well as several online calculators. Suffice it to say that Tw is always lower than Ta at less than 100 percent relative humidity: this underscores the greater efficiency of the cooling tower compared to the dry cooler. An element to consider when choosing the best cooler.
On the other hand, in terms of resource use, the cooling tower requires water for its operation where the dry cooler, by definition, does not use this resource for its operation.
Are performance (and the thermal jump to be achieved), space available for installation, or water savings more important for the system to serve? The answer to this question definitely begins to tilt the choice: dry cooler if the focus is on water savings, cooling tower if the greater need lies in performance and smaller available installation space.
Recall the structural differences between the two systems. A standard dry cooler works through a simple principle: the fluid to be cooled (usually water or water and glycol) is pumped through a series of pipes inside a unit. Outside air is forced through fins adjacent to the pipes, absorbing heat from the fluid and cooling it. This process occurs without the use of evaporation water. A dry cooler with an adiabatic device is a more advanced system that combines standard dry cooler technology with an adiabatic cooling process (which can be used at certain times of the year or day): in this case, the outside air is pre-cooled with water wetting cycles before making contact with the finned coil.
The fluid output in an adiabatic dry cooler can fall below the dry bulb temperature of the air (though not the wet bulb temperature). In contrast, a standard dry cooler cannot structurally achieve this. This difference is in itself a discriminating factor if the system to be served needs to dissipate heat at levels slightly above or slightly below this threshold, or some “guarantee” of performance is needed even on the hottest days or hours of the year.
The adiabatic dry cooler can also operate in standard mode, i.e., air-only and without a water pre-cooling device, if this is sufficient in certain seasonality-this is, of course, a point in favor of this equipment.
Want more information on Evaporative Condenser? Feel free to contact us.