How to select the type of air conditioner cooler according to the air inlet and outlet conditions?

The air-conditioning box surface cooler should be selected based on the design air volume, inlet dry and wet conditions, target air outlet conditions and cold water conditions. Only giving a total cooling capacity often cannot explain whether the coil can achieve the required moisture content; only giving the wind temperature cannot fully judge the dehumidification task.

Let the coil calculations correspond to the same set of air and water parameters

The air inlet parameters should be consistent with the actual fresh return air ratio and outdoor design conditions, and the air outlet target should indicate whether there are dehumidification requirements. The water side needs to confirm the supply and return water temperature, allowable pressure drop and flow conditions. If the water temperature adopts a temporary value, it should be indicated in the calculation book, because changes in water temperature may change the sensible heat treatment and condensation dehumidification capabilities at the same time.

The air inlet should be written with the fresh air volume, temperature, humidity or moisture content and air density conditions; the air outlet should be written with the target temperature, moisture content and whether subsequent reheating is required; the water side conditions should be written with the supply and return water temperature, available flow rate and allowable water resistance. Only when the three sets of parameters are placed in the same working condition table can the coil calculation have closing conditions. How to get the value of air inlet status, please refer toShould the inlet air temperature and humidity of the air conditioning box be designed to be outdoor or return air?。

The total cooling capacity cannot replace the air outlet state

Coils with the same total cooling capacity may have different outlet air temperatures and moisture contents under different water temperatures, air volumes, and inlet air moisture contents. The total cooling capacity only indicates the total amount of heat exchanged, but cannot indicate how much of it is used for cooling and how much is used for dehumidification. If the goal is to control room humidity, you need to check the sensible cooling capacity, latent cooling capacity and outlet air moisture content at the same time, rather than just looking at the total cooling capacity number.

The difference between dehumidification capacity and cooling capacity can be referred toHow to calculate the dehumidification capacity of air conditioning box from the difference in air moisture content? ;For the relationship between dew point and moisture control, please refer toWhat role does the supply air dew point play in the selection of fresh air air conditioning boxes? . If the project has clear requirements for humidity, the air outlet status should be written in terms of moisture content or dew point, not just dry bulb temperature.

Cold water conditions determine whether the coil can achieve its goals

The supply and return water temperature, flow rate and allowable pressure drop are the water side boundaries for coil selection. When the water temperature is high, even if the water volume is increased or the number of rows is increased, the air outlet may not be able to reach a low dew point; when the water volume is insufficient, the heat exchange capacity is also limited. How the coil water flow corresponds to the design cooling capacity can be referred toHow does the water flow rate of the air conditioning box coil correspond to the designed cooling capacity? . Parameters to be confirmed before connecting to the cold water system, please refer toWhat water parameters should be confirmed before connecting the air conditioning box to the cold water system?。

Water quality and media composition also affect coil materials and maintenance methods. When containing media such as ethylene glycol, the density and specific heat are different, and the water volume conversion cannot directly use the coefficient of ordinary water. When the water side data is incomplete, the coil calculation can only be tentative, and subsequent changes may affect the interface and overall machine size.

The number of coil rows and head wind speed should be looked at together.

Increasing the number of coil rows will usually change the heat exchange area and contact process, but the cooling capacity will not increase in proportion to the number of rows. Air volume, frontal area, fin structure, water temperature, water flow and loop layout all affect the results, and increasing the number of rows may also increase air resistance and change waterside characteristics. The more coil rows, the greater the cooling capacity. Please refer toWill the greater the number of coil rows in an air-conditioning box, the greater the cooling capacity?。

Head-on wind speed affects heat transfer and the risk of water entrainment under wet conditions. If the wind speed is too high, water droplets may be carried, and if the wind speed is too low, the coil area may be underutilized. For the influence of wind speed facing the coil, please refer toWhat impact does the coil head-on wind speed have on heat exchange and water entrainment in the air conditioning box? . Under wet working conditions, it is also necessary to check the water tray, water retaining and drainage conditions, please refer toHow to combine the slope of the water pan of the air-conditioning box with the layout of the drain outlet?。

How to check a coil selection result

It should be checked whether the total cooling capacity, sensible cooling capacity, air outlet status, air resistance and water resistance meet the requirements at the same time. Coils with the same total cooling capacity may have different dehumidification performance. If the actual water temperature is higher than the design condition, the wind output results should be recalculated and the missing heat exchange temperature difference cannot be made up by increasing the fan speed.

Coil selection should also be checked with the sequence of functional sections, mixing section length and fan operating point. For the arrangement of functional segments, please refer toOn what basis should the sequence of functional sections of the air conditioning box be determined? ;Mixing uniformity can be referred toHow long is the air mixing distance required in the mixing section of the air conditioning box? ;Fan pressure budget can be referred toHow is the total pressure of the air conditioning box fan determined by the internal resistance and external demand?。

Aili industrial supporting equipment

When submitting the Aili Industrial Checklist cooler, priority should be given to attaching a complete air inlet and outlet status table and cold water information to ensure that the coil configuration is consistent with the air volume of the entire machine. Aili Industrial can jointly check coils, water trays, drainage structures, fans, and control configurations; the manufacturing end covers independent R&D and production of motors and fans, control systems, sheet metal, air filters, and complete machine assembly. Coil water resistance, air resistance, and functional section interfaces can be aligned in the same package.

Product form can be viewedAir handling unit andFan box page; clean air supply package can be combinedFFU fan filter unit andHEPA/ULPA filter verification; when it comes to gaseous pollution control, you can communicate separatelyChemical filter solutions. The specific heat exchange effect, applicable environment and delivery scope still need to be verified based on the corresponding configuration data and on-site working conditions. Actual results are subject to on-site leak detection and performance test results.

Submit project parameters:https://ailigy.com/contactus.html

Related questions and answers

Can the surface cooler selection be completed only if the total cooling capacity is given?
not enough. The total cooling capacity cannot explain the moisture content of the outlet air and the distribution of sensible and latent heat. It also requires the state of the inlet and outlet air and cold water conditions.

If the outlet air temperature reaches the target, does it mean that dehumidification also meets the requirements?
uncertain. When the outlet air temperature reaches the standard, the moisture content may still be high. Humidity control should be based on the wind moisture content or dew point.

Can Aili Industrial help check the selection of surface cooler?
The coil configuration and interface can be checked based on the air volume, air inlet and outlet status, and cold water conditions. The specific plan needs to be confirmed based on the project conditions.

Related articles

1. How does the water flow rate of the air conditioning box coil correspond to the designed cooling capacity?

2. Will the greater the number of coil rows in an air-conditioning box, the greater the cooling capacity?

3. What impact does the coil head-on wind speed have on heat exchange and water entrainment in the air conditioning box?

4. How to calculate the dehumidification capacity of air conditioning box from the difference in air moisture content?

Key points for selection and acceptance inspection