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

Increasing the number of coil rows will usually change the heat exchange area and contact process, but the cooling capacity will not unconditionally 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.

Why do you get the wrong conclusion by just comparing the rankings?

Similarly, six-row coils can use different pipe diameters, plate spacings, loops and sizes, and their performance is not the same. If the cold water temperature is already high, simply increasing the number of rows may not necessarily achieve a very low air outlet moisture content. If the fan pressure is not checked synchronously after adding rows, the actual air volume will decrease, and the performance of the whole machine may also deviate from the original selection result.

The heat exchange results should be compared with the total cooling capacity, sensible cooling capacity and air outlet status under the same working conditions; the air cost should be compared with the air resistance, unit length and fan operating point; the water side cost should be compared with the water resistance, flow rate, circuit and available pump pressure difference. The three items correspond to different costs, so you cannot just count one number. How to select the type of surface cooler according to the air inlet and outlet conditions, please refer toHow to select the type of air conditioner cooler according to the air inlet and outlet conditions?。

What does increasing the number of rows increase?

Increasing the number of rows mainly increases the heat exchange area and contact path on the air side. When the air volume, water temperature, water flow rate and head-on area remain unchanged, increasing the number of rows can usually increase the heat transfer amount, but the increase will decrease as the number of rows increases. The heat exchange temperature difference of the first few rows of coils is large, and the air contacted by the latter rows is already close to the water temperature, so the contribution of the new area gradually decreases.

Increasing the number of rows will also increase the air side resistance, and the fan needs to provide higher pressure or reduce the air volume. If the fan margin is insufficient, the actual air volume will decrease and the heat exchange effect may be offset. How to establish the fan pressure budget, please refer toHow is the total pressure of the air conditioning box fan determined by the internal resistance and external demand? . What functional segments does internal resistance include? Please refer toWhat functional segments should be included in the internal resistance of the air conditioning box?。

Cooling capacity is also limited by water side conditions

Coil cooling capacity depends not only on the air side area, but also on the cold water temperature, water flow rate and circuit layout. When the water temperature is high, even if the number of rows is increased, the heat exchange temperature difference is still limited. When the water flow is insufficient, the average water temperature of the coil will increase and the heat transfer will also be limited. Improper circuit layout may lead to short circuits on the water side of some coils or uneven flow distribution.

How the coil water flow corresponds to the design cooling capacity, please refer toHow does the water flow rate of the air conditioning box coil correspond to the designed cooling capacity? . What water parameters should be confirmed before connecting the air-conditioning box to the cold water system? Please refer toWhat water parameters should be confirmed before connecting the air conditioning box to the cold water system?。

Head wind speed and fin structure also affect the results

The head wind speed affects the contact time between the air and the coil and the heat transfer coefficient. When the wind speed is too high, the contact time is shortened and the risk of water entrainment increases; when the wind speed is too low, the coil area is underutilized. Fin spacing, fin form and tube diameter also affect heat transfer and air resistance. If you increase the number of rows and reduce the fin spacing at the same time, the air resistance may increase significantly.

For the influence of coil head-on wind speed on heat transfer and water entrainment, please refer toWhat impact does the coil head-on wind speed have on heat exchange and water entrainment in the air conditioning box? . For the risk of water contamination under wet working conditions, you also need to check the water tray and water retaining structure. Please refer toHow to combine the slope of the water pan of the air-conditioning box with the layout of the drain outlet?。

The moisture content of the outlet air can better reflect the dehumidification ability than the total cooling capacity.

For projects that require dehumidification, an increase in total cooling capacity does not necessarily mean a decrease in the moisture content of the outlet air. The distribution of sensible and latent heat depends on coil surface temperature, contact time and waterside conditions. If the coil surface temperature is not low enough, the total cooling capacity may be used primarily for cooling rather than dehumidification. When evaluating a coil's dehumidification capacity, look at the outlet air moisture content or dew point, not just the total cooling capacity.

How to calculate the dehumidification capacity from the air moisture content difference, please refer toHow to calculate the dehumidification capacity of air conditioning box from the difference in air moisture content? . The role of supply air dew point in selection can be referred toWhat role does the supply air dew point play in the selection of fresh air air conditioning boxes?。

Let ranking become the configuration result rather than the only goal

You can first determine the air outlet state and allowable resistance that must be achieved, and then calculate the matching structure from the coil. If you really need to compare different row number schemes, you should lock in the air volume, water temperature, flow rate and head size to view the complete calculation results. Only in this way can we know what problem the extra rows are used to solve and whether it is worth the corresponding space and operating costs.

The sequence of functional sections and unit length will change with the number of coil rows, please refer toOn what basis should the sequence of functional sections of the air conditioning box be determined? . Whether the length of the device can be compressed when space is limited, please refer toCan the length of the horizontal air conditioning box be reduced when there is insufficient plane space?。

Aili industrial supporting equipment

Aili Industrial can check the coil and fan matching according to the same working conditions. It is recommended to use the calculation results to confirm the configuration instead of directly writing more rows as higher performance. Aili's industrial manufacturing end covers independent research and development and production of motors and fans, control systems, sheet metal, air filters and complete machine assembly. The number of coil rows, water resistance data and fan working points can be corresponded in the same set of supporting information; non-standard coils can be adjusted according to air volume, water temperature, head wind speed and allowable resistance.

Product form can be viewedAir handling unit andFan box page; clean air supply package can be combinedFFU fan filter unit andEFU equipment end fan filter unit verification; terminal particle filtration can be combinedHEPA/ULPA filter confirmation; when it comes to gaseous pollution control, you can communicate separatelyChemical filter solutions. The specific coil performance, applicable conditions and delivery scope still need to be verified based on the corresponding configuration data and on-site working conditions. The actual effect is subject to on-site debugging and performance test results.

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

Related questions and answers

The more coil rows, the greater the cooling capacity?
uncertain. Increasing the number of rows usually increases the heat exchange area, but the cooling capacity is also affected by air volume, water temperature, water flow, head-on wind speed and fin structure. The increase will decrease and the resistance will also increase.

What is the reason for the decrease in air volume after increasing the number of rows?
Increasing the number of rows will increase the air side resistance. If the fan margin is insufficient, the actual air volume will decrease, which may offset part of the heat exchange gain.

Can Aili Industrial help compare different arrangement options?
The coil configuration can be checked based on the air outlet status, allowable resistance and water side conditions. The specific plan needs to be confirmed based on the calculation results and on-site working conditions.

Related articles

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

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

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

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