How to Calculate Hydraulic Oil Cooler Capacity

In every hydraulic system, heat is the most powerful enemy. Temperatures that are high can degrade the viscosity of oil, affect seals, and cause the components, such as motors and pumps, to wear out over time.

To ensure that your system is running efficiently, you require an oil cooler (hydraulic heat exchanger) capable of handling all the heat load. How can you figure out the exact amount of cooling capacity you'll need?

Calculating the capacity required in Kilowatts ( kW) isn't a matter of guesswork. It's an amalgamation of physics and observation. This is how you can calculate it.

Why Heat Happens

Before calculating the amount of heat, we must know where the heat originates. In a perfect scenario, the entire hydraulic power would be used for performing work. However, internal leakage and friction convert some of the force into heat.

As a rule of thumb, approximately 25-30 percent of the input motor force is lost in heat in a conventional hydraulic system.

Method 1: The "Rule of Thumb" Calculation

If you're at the beginning of the design phase and don't have an operational machine to gauge the cooling power based on the total power installed in total.

• P_cool: Required cooling capacity (kW)

• P_in: Total input power of the electric motor or engine ( kW)

• eta_loss: The percentage of power lost to heat (usually 0.25 to 0.30)

Example: If you have an 50 kW motor, then you need to choose a cooler that is capable of dispersing roughly 12.5kW up to 15 kW of heat.

Method 2: The "Temperature Rise" Calculation (Most Accurate)

If you already have a system, the best method of determining the cooling requirements is to gauge how fast the oil gets heated when it is in use.

Step-by-Step Instructions:

1. Get Cold Take note of the first temperature of the oil.

2. Use the Machine: Operate the system with normal loads for a specified time (e.g., 20 minutes).

3. Take a Measure of the Rising: Note the final temperature.

4. Calculate Enter your data into the equation to determine the kW of heat being generated. of heat produced.

Factors That Influence Your Choice

When you've got your kW dollar number, you're not completely done. You have to choose the cooler that will give you the kW value rating for your specific operating conditions.

• oil flow rate. Coolers have been rated according to specific rates of flow (LPM). If your flow is low, the fluid stays longer in the cooler; however, it is able to move less heat.

• Ambient Temperature. The cooler, which is effective in the Arctic, will not be able to work within the Sahara. You need to account for your "Entering Temperature Difference" (ETD)-the difference between warm oil and cooling media (air or even water).

• altitude In the case of an air-cooled heater, the thinner air at higher altitudes is less effective at transporting heat.

Summary Checklist

• [ ] Calculate the total power input.

• [] Estimate heat loss (usually 30%).

• If the system is present If the system is in place, conduct the Temperature rise test.

• Make sure to check for the manufacturer's Performance Curves to verify that the $kWvalue rating is consistent with the actual flow and the ambient temperature of the air.

Need a hand with the math?

Calculating the exact temperature and density of the fluid can be somewhat "math-heavy" depending on the kind of fluid you're employing.