Understanding Cooling Capacity in Water Chillers: Flow Rates, kW, and What You Really Need to Know

When it comes to industrial water chillers, one of the most common points of confusion is the relationship between flow rate, cooling capacity, and the actual performance of your system. Whether you're cooling a laser, welding system, CNC machine or other industrial process, getting this balance right is critical for long-term reliability and efficiency.

At Plasquip Sales, we supply the trusted S&A TEYU range of water chillers — known worldwide for their reliability, smart design, and excellent cooling performance across a wide range of industrial applications.

❄️ Does Cooling Capacity Change with Flow Rate?

Here’s the key point:

A chiller’s cooling capacity in kilowatts (kW) does not change based on the water flow rate.

Cooling capacity is a measure of how much heat (in kW) the chiller can remove from your system every hour. What changes with flow rate is the temperature difference (∆T) — that is, how much the water heats up as it passes through your equipment.

🔢 Basic Cooling Capacity Formula

To estimate your cooling needs, you can use this basic formula:

Cooling Capacity (kW)=m˙×Cp×ΔT3600Cooling Capacity (kW)=3600m˙×Cp×ΔT

Where:

• m˙m˙ = water flow rate in kg/h (for water, 1 L ≈ 1 kg)

• CpCp = specific heat capacity of water = 4.186 kJ/kg·°C

• ΔTΔT = temperature difference (°C)

• 3600 = seconds in an hour (converts kJ/h to kW)

💡 Real-World Example

Let’s say your chiller is rated at 10 kW of cooling at 200 L/h. You can calculate the temperature difference:

10=200×4.186×ΔT3600⇒ΔT≈43°C10=3600200×4.186×ΔT⇒ΔT≈43°C

Now if you increase the flow to 300 L/h, the temperature rise becomes:

ΔT=10×3600300×4.186≈28.6°CΔT=300×4.18610×3600≈28.6°C

And if you reduce the flow to 100 L/h, it jumps to:

ΔT≈86°CΔT≈86°C

As you can see, the chiller still removes 10 kW of heat, but the water heats up (or cools down) more or less depending on the flow rate. This can have a big impact on your process temperature stability.

⚠️ What If You Need a Lower Flow?

If your process requires a lower flow than what the chiller is designed for, don’t just restrict the flow — this can cause system instability, high ∆T, and chiller faults.

Because our S&A TEYU chillers do not have variable capacity, we recommend the following options to safely operate at lower flow:

✅ Add a buffer tank – Increases total water volume in the loop, smooths out temperature fluctuations, and improves consistency.
✅ Install a flow bypass – Maintains the minimum flow rate through the chiller while diverting excess water around the process.

Both methods help protect your system and keep the chiller running efficiently.

🧰 Practical Support from Plasquip Sales

Choosing the right chiller isn’t just about hitting the right number in kW — it’s about understanding your full cooling loop. At Plasquip Sales, we help customers across Australia with:

• Chiller sizing and selection

• Flow rate and system optimisation

• Buffer tank and bypass design

• Installation and support advice

We proudly supply the full S&A TEYU range of water chillers and offer reliable pre- and post-sale support.

📞 Need Help Choosing the Right Water Chiller?

If you’re not sure what size chiller you need — or you’re working with a unique setup — get in touch with Plasquip Sales today. We’ll help you get it right from the start.

👉 [Contact us] or call Peter on 0438 382 850