For evaporative cooling towers to work effectively, they must use water. But water usage will vary greatly depending on the style of tower, the application and the conditions of the water entering the system. Below are some FAQs we hear often as manufacturers of cooling towers; the answers here might help you understand more about water usage in your new or existing mechanical system.
蒸发式冷却塔会浪费大量水吗？
It’s been said that “the purpose of a cooling tower is to conserve water. It fulfills its purpose by rejecting heat to the atmosphere by convective and evaporative heat transfer.” (Power Magazine, 2009) The only water “lost” is the pure water that is evaporated; the remaining cooled water is eventually blown down, or drained, and sent back into the water system.
Generally speaking, the lower the heat load and/or ambient temperature, the less evaporation. The higher the system’s cycles of concentration (COC), the lower the blowdown. For more about limiting evaporation and/or blowdown, see our white paper, “如何节约蒸发冷却塔的用水”
水冷塔比风冷塔用水量大吗？
Water-cooled towers, like the 马利 NC® Everest® 冷却塔, use far less energy than air-cooled solutions on-site. But, operators of water-cooled solutions may see higher water usage and costs at their location. Keep in mind, as stated in ASHRAE Journal, “the hidden reality is that air-cooled or alternative systems consume more energy on-site [AND] use substantially more water at the power generation site… (“蒸发冷却的效率和环境价值的回顾。”)
Another water-saving option that’s becoming more popular for a variety of applications is an adiabatic cooling system. For example, the Marley® OlympusV™ 绝热系列 balances the water-saving benefits of an air-cooled heat rejection system with the energy efficiency of a water-cooled solution to provide flexible cooling for a variety of operations.
我如何知道我正在使用或将要使用多少水？
There are several tools available from manufacturers to help determine cooling tower water estimates. If you know conditions of your specified/installed cooling solution, you can enter them into the Marley 水计算器。此工具还可以帮助您确定特定的条件改变如何帮助您限制用水量。
如果您需要帮助确定项目或建筑的条件， 附近的 Marley 代表 可以帮助您收集正确的信息并找到节约用水的最佳解决方案。
改变循环流量可以减少用水量吗？
In short, no. Evaporation rate closely follows heat load, regardless of whether water flow rate is high or low. The liquid-to-gas ratio – also known as L/G (defined as mass flow of water divided by mass flow of air) – has a small impact on evaporation. If the amount of water is less than the amount of air (a low L/G ratio), more evaporation can occur and vice versa. A product’s configuration and target thermal conditions dictate the airflow required. A makeup water optimizer like the Marley WaterGard™ system might be a better option in some cases, which can limit water use onsite without adjusting your flow rate.
蒸发率会根据位置而变化吗？
Yes, evaporation is directly impacted by the ambient conditions. The air in warm, dry climates is very low relative humidity. This atmosphere naturally can accept more water vapor, which drives up evaporation rate. Conversely, a product with the same configuration installed in a more-humid environment will display a lower evaporation rate.
Another primary factor is elevation. Barometric pressure decreases as you reach higher altitudes and, in turn, evaporation rate increases.
In the end, there are no universal rules that apply to water usage in every application and climate zone. The drivers of water usage in cooling towers are heat load, climate, and load profile throughout the year – and water quality can also play a major role.
If saving water is important to you and your mechanical system, learn about more water-saving options and/or contact your local Marley representative.
