Cooling unit cooling capacity calculation formula

Cooling Capacity and Water Flow Calculation for Chillers

Choosing the right industrial chiller or small group chiller is actually quite straightforward. There's a simple formula to calculate the cooling capacity: Cooling Capacity = Water Flow × Temperature Difference × Coefficient × 4.187.

The water flow refers to the amount of chilled water required for the machine operation, and it should be converted into liters per second. The temperature difference is the difference between the inlet and outlet temperatures of the chiller. The number 4.187 represents the specific heat capacity of water. When selecting an air-cooled chiller, multiply by a factor of 1.3, while for a water-cooled chiller, use a factor of 1.1.

Once you have calculated the cooling capacity, you can choose the appropriate chiller model based on that value. Although some people use P (pounds) to estimate the size of the chiller, the most important factor is knowing the rated cooling capacity. For example, a 9.07KW air-cooled chiller may appear similar to a 3P unit, but understanding the actual cooling capacity is essential when selecting an industrial chiller.

Formula for Calculating Chiller Cooling Capacity:

There are several methods to calculate the cooling capacity of chillers. One common approach is the temperature difference flow method: Q = Cp × r × Vs × ΔT, where Q is the heat load in kW, Cp is the specific heat of water (approximately 4.1868 kJ/kg°C), r is the density of water (1000 kg/m³), Vs is the water flow rate in m³/h, and ΔT is the temperature difference in °C.

Another method is the time rise method: Q = Cp × r × V × ΔT / H, where V is the total volume of water in m³, and H is the heating time in hours. This helps determine how much energy is needed to raise the temperature of the water over a given period.

Additionally, the energy conservation method calculates the heat load as Q = W_in - W_out, where W_in is the input power and W_out is the output power. This is useful for systems where the energy transfer is directly measurable.

For industrial applications, a commonly used formula is Q = W × C × ΔT × S, where W is the weight of the raw material in kg/h, C is the specific heat of the material in kcal/kg°C, ΔT is the temperature difference in °C, and S is the safety factor (typically between 1.35 and 2.0). This method is especially helpful in processes like plastic molding, where precise cooling is required.

Understanding these formulas and applying them correctly ensures that you select the right chiller for your application, optimizing both efficiency and performance.