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The causes and preventive treatment of condensation water in air conditioners
2025/6/25
Condensate water comes from the cooling process of the indoor unit of an air conditioner. When the surface temperature of the heat exchanger is lower than the dew point temperature of the indoor air, it causes the water vapor in the air to condense upon cooling, forming liquid water. This condensate water then flows out from the water collection tray below the evaporator and is smoothly discharged through the condenser tube.
Theoretical reasons:
During the process of heat exchange and heat absorption with the outdoor air, the wall temperature of the surface cooler of the air conditioner's main unit is lower than the dew point temperature of the outdoor air. At this point, the water vapor contained in the outdoor air will condense into dewdrops on the wall of the surface cooler. When the dewdrops accumulate to a certain scale, they will slide down to the condensate pan below the surface cooler and eventually form condensate water.
Actual reason:
Unreasonable design of the fresh air and exhaust system: Improper setting of the fresh air and exhaust system in the air-conditioned area may lead to excessive negative pressure, causing untreated outdoor air to enter the room disorderly, increasing air humidity and dew point temperature. When the surface temperature of the air outlet is lower than the dew point temperature of the air seeping into the room, condensation at the air outlet will occur. Substandard insulation materials: In air conditioning projects, the selection and application of insulation materials are of vital importance. If the thermal conductivity of the insulation material exceeds the standard, its thickness is insufficient, it falls off, or its performance does not meet the design requirements, it may lead to increased heat loss, reduced air conditioning effect, and serious condensation problems. Large temperature difference air supply: To reduce costs, some air conditioning systems adopt low-temperature air supply technology, reducing the air supply volume and fan power. However, an excessively low supply air temperature can easily cause water vapor in the air to condense rapidly near the supply air outlet, forming condensate water. High relative humidity: Poor air flow organization or excessive humidification may cause the relative humidity of the air in the air conditioning outlet area to increase, the dew point temperature to rise, and thus it is easy to form condensation water. The heat exchange process at the terminal of an air conditioner: When the terminal of an air conditioner is cooling and dehumidifying the indoor air, the temperature of its wall surface is lower than the dew point temperature of the indoor air, causing the water vapor in the air to condense into dewdrops here. When dewdrops accumulate to a certain extent, they will slide down to the condensate pan below the end, forming condensate water. Ii. Strategies for Preventing Condensation Formation \ nBased on a deep understanding of the causes of condensation in air conditioning systems, the following effective preventive measures are proposed for each influencing factor:
Optimize the design of the fresh and exhaust air system: By adjusting the ratio of fresh and exhaust air, maintain a slightly positive pressure indoors to prevent the infiltration of hot and humid air and the formation of condensation. At the same time, make sure that doors and Windows are closed during the operation of the air conditioner to prevent the entry of hot and humid air from the outside. By taking advantage of the dehumidification capacity of the air conditioner itself, the indoor humidity will gradually decrease as the operation time goes by, thereby reducing the formation of condensation water. Select and precisely calculate insulation materials: Strictly choose insulation materials that meet the design requirements to ensure that parameters such as bulk density, thickness, and heat transfer coefficient are up to standard. Based on the principle of preventing condensation, accurately calculate the thickness of the insulation layer to ensure that the surface temperature of the pipeline and equipment is higher than the dew point temperature of the air outside the insulation layer, and avoid condensation to the greatest extent. Reduce the temperature difference of supply air: By increasing the supply air volume, raising the supply air temperature or increasing the supply air speed, the supply air temperature can be made to meet the design requirements, preventing condensation caused by low-temperature supply air. It can usually be solved by adjusting the flow rate of chilled water or increasing the supply air temperature, etc. Regulate the indoor relative humidity: Maintain the indoor relative humidity within the optimal range (approximately 49% - 51%). Dehumidification can be carried out with the help of a dehumidifier, or under the premise of meeting the indoor hygiene conditions, the ratio of fresh and return air can be appropriately adjusted, reducing the volume of fresh air and increasing the dehumidification capacity to ensure that the supply air state points meet the dehumidification requirements. Use air outlet materials with low thermal conductivity: Selecting materials with low thermal conductivity to manufacture air outlets, such as wooden ones, helps reduce condensation at the outlet. When the indoor humidity is too high, the air temperature can be appropriately increased. Adjust the structure of the air outlet or add auxiliary facilities: For louvered air outlets, the blade Angle can be adjusted to increase the turbulence at the outlet. Or add thin PE insulation boards at the edge of the existing central air conditioning outlet, or increase the air volume to reduce the risk of condensation. Iii. Design of Air Conditioning Condensate Drainage System \ nFor the central air conditioning projects of large-scale comprehensive buildings such as hotels, there are usually three ways to discharge condensate:
Independent drainage system: A dedicated condensate drainage pipeline system is established, and the condensate is directly discharged into the designated drainage ditch. This method is conducive to the discharge of condensate water, but it is necessary to ensure that the installation site has sufficient space and a suitable location. It is recommended to give priority to this method when conditions permit. Floor collection and discharge: Each floor is equipped with a separate condensate water discharge pipeline, which is then collected and connected to the main sewage drainage pipe on a certain floor of the building. To prevent condensation on the horizontal main pipe, an insulation layer of appropriate thickness should be installed on its outside. Connect the nearest drainage pipe: Connect the nearest drainage pipe to the terminal of each air conditioner. This method is simple and quick, but attention should be paid to the problem of condensation on the outer wall of the drainage pipe that may be caused by the discharge of condensate water. After the drainage pipes are installed on the floor, a water filling test should be conducted to check whether the drainage slope is sufficient and whether the drainage is smooth. Any problems found should be rectified in a timely manner.
