Evaporative cooling pads are a great way to limit heat stress in your poultry and greenhouse environments. They are easy to use, inexpensive, and require little maintenance.
Cool pads absorb and release heat to the air by converting sensible heat into latent heat (drop in air temperature). A few factors can influence the effectiveness of a pad system.
Temperature
Evaporative cooling pads lower the temperature of hot outside air passing through them by converting it to humid, cool air. Typically, for every gallon of water evaporated, 8,700 Btu of sensible heat is removed from the greenhouse, decreasing the air temperature (temperature drop), and increasing air humidity (air moisture).
The cooling capacity of your pad system depends on several factors, including the outside air temperature, the wet bulb temperature, how many times you use the pads per day, and your facility’s ventilation design. To maximize the efficiency of your pad system, we recommend using it at least once a day to remove heat and moisture from the greenhouse and prevent the build-up of hard water on the pad surface.
In addition, to minimize the risk of clogging and algae growth, you must keep the pad water circulating through the system. This can be accomplished by a continuous bleed-off or periodic flushing of the sump. The sump should also be screened to prevent the flow of any pad fibers into the pump or distribution tubes.
Another important factor to consider when running the pads is the outdoor air condition and relative humidity. The cooler the outside air temperature, the less cooling effect the pads generate. There is a “tipping point” at which running the pads will provide minimal benefit. If the outside air temperature is below 80°F, the pads will not have much impact on lowering the greenhouse air temperature.
Pads are only one part of the overall broiler house cooling system; tunnel fans are the other key component. When combined with good ventilation, evaporative cooling systems limit bird heat stress and can be more cost-effective than other methods.
When you’re looking for a high-quality evaporative cooling solution, turn to J&D Manufacturing. Our team has the knowledge and expertise to help you find a system that’s right for your operations. Contact us today to learn more about how our products can make your farm more productive. We are proud to offer industry-leading solutions that help you achieve the best results for your crops, livestock, and poultry.
Humidity
Evaporative cooling pads enhance the cooling effect of a greenhouse by creating a large surface area of water that is exposed to air being drawn into the greenhouse through exhaust fans. The cooler water absorbs the heat in the incoming air, lowering the air’s wet bulb temperature and raising the air’s relative humidity. The higher the air humidity, the less effective the evaporative cooling system is. The optimum relative humidity for evaporative cooling is 40%, and this level can only be achieved with the use of a dehumidifier to reduce humidity in the greenhouse prior to evaporative cooling.
In a typical evaporative pad system, the water is fed into a series of honeycomb-shaped pads made from corrugated cellulose or cardboard. The dense honeycomb structure maximizes the surface area of the pads for water saturation and availability. The pads are then surrounded by water in a channel to catch the unevaporated water. The pad water can be fed from a water pipe running across the top of the pads or through an evaporative fan that blows the wet pad surfaces outward for evaporation.
The most commonly used type of pad for a standard cooler is corrugated cellulose that has been impregnated with wetting agents and soluble salts to prevent algae growth and rot. These pads are available in two sizes, 8” and 12”. The thicker the pad, the more water it can absorb. Pads should be cleaned regularly to remove hard water mineral buildup and replaced every 3-5 years.
A new evaporative pad system should be calibrated to provide the maximum cooling it was designed for by adjusting the water flow and fan speed to achieve the desired wet bulb temperature. This can be done using a spreadsheet provided by the University of Georgia Cooperative Extension Service. The spreadsheet allows the user to select different airflow, water pressure, pad size, and humidity conditions and compare the amount of cooling produced.
When used properly, evaporative cooling pads are a great tool to reduce heat stress on crop plants. But they should never be run 24 hours a day. Over time, continuously running pads increase the risk of algae growth and shorten the pad life expectancy. Keeping pads wet for extended periods also creates high levels of greenhouse humidity that can increase the likelihood of disease.
Airflow
Evaporative cooling systems use a combination of pads, a water pump, and a fan to cool air. They are used for human comfort in houses, workplaces, and warehouses and for poultry farmhouses, greenhouses, and other commercial uses. They can help minimize the number of birds lost due to heat stress. They also provide a source of moisture and increase humidity in the environment. However, they do not cool as well in areas with low air movement. To enhance cooling efficiency, ensure that your evaporative coolers have enough air movement and are located away from heating sources.
Evaporation of water requires energy, which comes from whatever the wet pad touches when it evaporates. In this case, the hot air being pushed through the cooling pads is the source of energy for evaporation. The resulting cooler air is then blown into the house by the fan.
The wet pads must be constantly re-dampened to continue the cooling process, which means that air is continuously passing through the pads. The cooling pads themselves cannot cool the air directly, as they are not designed to absorb any significant amounts of heat.
A typical residential evaporative cooling system consists of an open box mounted on the roof (down draft or downflow) or exterior walls or windows (side draft or horizontal flow). It draws air through vents on the sides of the unit and through water-soaked pads. The pads are usually made of corrugated cellulose paper that complies with environmental pollution regulations and is resistant to rot. Pads made of aluminum or plastic are available but are more expensive and do not perform as well as cellulose pads.
To ensure maximum effectiveness, the evaporative cooling pads should be inspected on a regular basis for signs of wear and tear, such as sagging or bird nests. They should also be cleaned and flushed three to four times per month to remove trapped dirt and organic debris that can reduce their efficiency. It is important to note that the water distribution pipe holes must be clear in order for evaporation to occur, so it is important to check these regularly. If the distribution pipes become clogged, the water flow will be reduced, and the pad performance may suffer.
Water
Evaporative cooling systems use a series of water-soaked pads to cool greenhouse air. These pads are typically located directly in front of intake fans. As the fan pulls outside warm air into the barn, it passes through the pads where heat exchange occurs with the cooled water. As a result, the air temperature drops dramatically.
Keeping animal barns cool is vital to maintaining healthy livestock. In hot climates, high temperatures can cause heat stress, which can have negative impacts on the health and production of pigs, cattle, and poultry. Many farmers turn to evaporative cooling to keep their barns cooler and help protect their livestock from heat stress.
When selecting a pad system, selecting a material that can absorb and retain water well is important. The most popular option is corrugated cellulose. It’s inexpensive and provides great cooling capacity for standard evaporative coolers. Corrugated cellulose pads are also highly durable and, with proper maintenance, can last up to ten years in Florida conditions. Other pads, such as aluminum and plastic fibers, are available but are more expensive and provide less cooling capacity than corrugated cellulose.
The size of the pad system also affects cooling efficiency. A larger pad requires more airflow to properly fill the pad. A smaller pad, on the other hand, fills faster and allows more air to pass through. A correctly sized pad can improve cooling efficiency by reducing energy costs and limiting contamination.
Using the right amount of water in the pad system is also important to maximize the cooling effect. Too little water will not cool the air and may even increase greenhouse humidity levels. Too much water causes the pads to become wet and can lead to a number of problems, such as algae infestation, pad rot, and water sludge.
In addition to choosing the right type of pad, the pad system should be matched with appropriate controls. Ideally, a thermostat or controller should be used to control the cooling water pump. This can help optimize the response to changes in outdoor climate, reduce operating costs, and minimize excessive greenhouse humidity.
