Operation of evaporative cooling during seasons with high ambient temperature effectively reduces heat stress on flocks and as a result enhances performance and product quality for egg-producing, broiler and turkey flocks. The design of a system, the fabrication of pads and the quality and integration of components contribute to successful, long-term operation and a beneficial return on investment despite an initial higher capital investment.
The principle of evaporative cooling is based on the change in state of water from the liquid form to vapor with a resulting change in latent heat thereby reducing the temperature of incoming air passing across the moist cooling pad. The conversion of sensible heat to latent heat occurs at a constant enthalpy value resulting in a lower temperature of the air stream exiting the pad but with a higher humidity. Changes in temperature and humidity are determined by physical principles and can be related by reference to a psychrometric chart relating the relevant constants. (See companion article)
Lubing systems has acquired considerable experience in the design and manufacture of complete evaporative cooling systems. Lubing offers a range of components to suit both retrofits and original installations, applicable to a wide range of house sizes and environmental extremes.
OptiCOOL plastic pads are at the heart of the Lubing system. The pads are fabricated from polypropylene sheets with thermal welding, contributing to efficiency and a long service life. Additives in the plastic provide resistance to ultraviolet radiation and chemicals and the arrangement of the plastic pads effectively blocks incident light.
The OptiCOOL pad is designed to distribute water evenly across all cells contributing to efficiency of cooling. The configuration and durability of OptiCOOL pads is superior to conventional fiber alternatives.
Components of the Lubing evaporative cooling system comprise: -
The water-supply unit incorporating a centrifugal pump equipped with an integrated filter, a float valve to maintain water level in the system and with an operational flushing capability.
An arrangement of pipes to distribute water evenly over the entire length of the pad.
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A ball valve located in-line to replenish the quantity of water required during operation.
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A deflector with a hinged cover to accurately direct water flow to the pads A water gutter to collect and recirculate water limiting wastage.
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Design features of the Lubing system allow for ease of installation and maintenance. Components are secured with clips and pads are positioned and held in guides. OptiCOOL plastic pads 2’ in width weigh 14 lbs. wet compared with fiber pads at more than 50 lbs., contributing to lower maintenance of the system.
The Lubing evaporative cooling installation is fabricated from PVC and stainless steel to eliminate corrosion. The system does not require a water tank. The automatic float valve automatically replenishes water to maintain operation of the system through measured and filtered recirculation.
OptiCOOL pads can be cleaned using a pressure ranging from 1,300 to 1,800 psi without damage, effectively removing accumulated dust and mineral scale. Fiber pads progressively loose cooling capacity due to an accumulation of adherent dust, mineral deposit and algae. Early versions of the OptiCOOl plastic pad are currently operating with high capacity for over ten years subject to regular inter-cycle washing. In comparison it is necessary to purchase, replace and dispose of fiber pads at regular intervals.
Under field conditions it was determined that a house in Georgia fitted with OptiCool pads allowing 1ft2 pad area/350 cfm fan capacity operated at 0.1” swg. compared to a house with fiber pads that resulted in 0.2 swg. resistance. The more efficient OptiCOOL plastic pads contributed to a saving in power of $1,000 over a year during which cooling was used for 120 days with 13 fans activated.