AZEVAP - AZFlow Coolers Differentiated by Design…
AZFlow cooler features
There are many specific features that differentiate AZFlow technology coolers from those found on other commercially available coolers. These features address the limitations of evaporative cooling discussed previously under the history of evaporative cooling and are discussed below:
- Water distribution system - AZFlow coolers feature a patent-pending metered water distribution system that meters water uniformly onto the media at a rate that takes advantage of the rigid media's water storage capacity, wicking ability, and heat transfer properties. The water is applied by this system in a pattern matching the cooling heat load and doing so consistently along the width, length, and depth of the media. This is significantly different and more reliable when compared to the recirculating system of other coolers as there is no pump to recirculate the water, no float valve to add water to the sump, and no water sump to capture and store water for recirculation. This recirculating system maintains a water surface on the media such that the air does not contact the media but flows over the water film where the mass and heat transfer properties are not as good as they are when the air flows over wet media.
- Sensors and Control - AZFlow coolers sense inlet temperature and relative humidity and compute the instantaneous evaporation rate for the air flow rate. The local water chemistry is used to derive a desired cycles of concentration for the cooler that will minimize water use while avoiding scale formation. This cycles of concentration value is input to the micro processor control system along with the instantaneous evaporation rate to determine the quantity of fresh water to meter onto the rigid media. The resultant quantity of water added by the control system is such that all but the desired volume of bleed water is evaporated and the ratio of the water volume added to the bleed water volume equals the desired cycles of concentration.
- Fresh Water Rinse Cycles - During operation of the cooler, fresh water is applied to the top of the pads at the rate described above to achieve the desired cycles of concentration. To compliment this approach fresh water rinse cycles are applied on startup, during operation, and on shutdown. This provides additional protection against scaling by assuring the pads are well wetted on startup, rinsing the pads during operation to achieve a cycles of concentration of one at the bottom of the pads periodically, and to rinse the pads to achieve a cycles of concentration of one during system shutdown. These steps prolong the life of the media and improve the long term performance by limiting the formation of scale on the pads. Recirculating coolers continuously wet the pads with water that has reached the maximum mineral concentration such that there is a much higher likelihood of scaling.
- Uniform Air Velocity - AZFlow coolers are designed with the air flow path between the media and inlet to the fan arranged to promote a uniform air velocity across the media to avoid hot spots, avoid carry over, maximize the efficiency of the media, and minimize the fan horsepower requirements. Recirculating systems find it adds cost and reduces reliability to incorporate the multiple sumps, pumps, and valves necessary to achieve such a media to fan arrangement providing this a uniform air velocity.
- Graded Material Selection and Corrosion Protection - AZFlow coolers are engineered and fabricated with a combination of corrosion resistant materials selected to balance corrosion resistance, material costs, and application. Our wet sections are designed and fabricated out of stainless steel or other client-specified corrosion resistant materials, the fan and fan housing are fabricated out of galvanized steel, the plumbing is stainless or copper, and the conduit is reinforced plastic. Where metals are dissimilar, we address galvanic corrosion by controlling the cathode to anode area and add a dielectric insulator to increase the resistance of the electrical circuit between the dissimilar metals.
- Plug and play modular and skid mounted design - AZFlow coolers are designed with modular and skid mounted features that minimize the interfaces and associated actions necessary to complete installation of the cooler and assure uniform and predictable performance. The units are assembled; shop tested; and shipped as complete assemblies with limited interface points for (Power, Water, Drain, and Control).
- UL approved components - AZFlow coolers use only UL approved low voltage control and electrical components.
- Failure modes and mitigation features - A failure modes analysis has been conducted and mitigating features incorporated in AZFlow coolers to minimize the consequence of all potential failures. Failure modes analysis involves an engineering review where each potential component failure and the associated consequences are identified. Features have been added to achieve a fail safe configuration and where beneficial to mitigate the consequences of failure modes. This results in a highly reliable cooler able to continue operations with little degradation in performance, even when experiencing failures, until a convenient planned maintenance outage time is reached.
- Micro processor based graphical controls - AZFlow cooler controls are structured to interface with Local Area Network (LAN) and building energy management systems (where installed) at existing facilities. Internet explorer can be used from any and all desired network locations to access the cooler controls and manage cooler performance. The coolers control system consists of a combination of sensors and micro processor based controls that establish the capability to monitor and control the performance of the cooler. This includes the ability to determine the condition and performance of coolers without physically going to the cooler or using additional test equipment. A locally administered, multilevel, password-protected, security system is integrated into the control system used to manage access and interface with these computer controls. Unique control system features include the ability to trend cooler performance, diagnose and both send alerts / alarms and take compensatory / corrective actions when components fail or performance degrades. Multiple control options are available that address multiple cooler installations and cooler reliability.