Selection of cooling towers
When selecting a cooling tower for a particular device or system, a series of steps need to be followed. First, the total amount of heat rejection of the fluid must be determined, usually measured in Kw/h. Second, the desired inlet and outlet water temperature difference must be determined, which is particularly important in air conditioning projects because different cooling methods have different temperature difference requirements. For example, absorption chillers are generally set at a temperature difference of 8°C, while compression refrigerants are usually set at 5°C.

Next, a specific formula is used to calculate the required cooling water volume in m3/h. This formula involves multiple parameters such as the total amount of heat rejection of the fluid, the temperature difference, and the specific heat of water. It should be noted that different cooling methods use different coefficients in the calculation, such as 3.0 for absorption chillers and 1.56 for compression refrigerants.

In addition, local meteorological conditions, especially wet bulb temperature, need to be considered. When the wet bulb temperature is less than 27°C, there is generally no need to increase the design margin. However, if the atmospheric wet bulb temperature at the installation site is higher than this value, the design needs to be adjusted accordingly.

Let’s take a specific example: when selecting a cooling tower for a lithium bromide refrigerator with a cooling capacity of 1160KW/H, the temperature of the refrigerant cooling water is required to be no more than 32℃, and the atmospheric wet bulb temperature at the installation site is 28℃. In this case, we use the correlation coefficient and formula of the absorption type to calculate and get the nominal water volume of 373m3/h. Therefore, a cooling tower with a model of 375 or 400m3/h can be selected, and its temperature difference can meet the design requirement of 40-32=8℃.