Selecting a Liquid-to-Liquid Cooling System

How to Calculate which Liquid-to-Liquid Cooling System is Right for Your Application

In most Liquid-to-Liquid Cooling applications, we know the temperature of facility water (TF), the desired process set-point temperature (TP), the flow rate through the process ( P) and the heat load of the process, Q.

Liquid to Liquid Diagram

To determine the required capacity, Q/ITD, we first need to calculate the change in temperature, ΔT, through the process. We can do this either by solving the heat capacity equation:

 

Heat Transfer Liquid Cooling Equation

or by using the heat capacity graphs found in our Thermal Reference Guide.

Next, we calculate Q/ITD to find the required cooling capacity. Q is the process heat load. ITD, the initial temperature difference, is the difference in temperature between warm return water, (TP+ ΔT) and cold facility water (TF). 

Liquid Cooling Equation

Finally, refer to the Liquid Cooling System (LCS) performance curves to determine the facility process flow rate required to achieve calculated Q/ITD.

Example Liquid-to-Liquid Cooling System Calculation

A solder reflow oven requires a process set point of 20 °C. The heat load is 10 kW and process water flow rate is 5 gpm. The facility water is at 10°C.

Using the heat capacity graphs, we find that the ΔT through the process is approximately 7.6°C for the condition 10 kW at 5 gpm.

We can now solve for Q/ITD as follows:

Heat Transfer Liquid Cooling Equation

Referencing the LCS performance graph, we can see that a facility flow rate above 2 gpm will meet required performance.

Liquid Cooling Performance Graph
Liquid Cooling Water Temperature Graph

View our Ambient Liquid Cooling Systems Section or our Recirculating Chillers Section to learn more about available options.

Have questions? We're ready to help!