Application and cleanliness control of plate heat exchanger in liquid cooling system

In the high-heat-generating 'heart' of data centers and energy storage stations, liquid cooling technology has emerged as the dominant solution for heat dissipation. Within this sophisticated system, a critical component acts as a 'heat transfer hub' —its condition directly determines the system's efficiency and safety. This pivotal component is the plate heat exchanger.

I. The "gatekeeper" of liquid cooling system: plate heat exchanger

Imagine liquid cooling systems where expensive, high-purity coolant flows directly through sensitive components like CPUs and GPUs, demanding absolute purity. In contrast, external cooling towers or municipal water, while more cost-effective, inevitably contain impurities, minerals, and microorganisms.

How do you get the internal liquid to transfer heat to the external liquid without mixing them?

At this point, it is time for the plate heat exchanger to shine!

Plate heat exchanger is made of a large number of stainless steel and other metal plates stacked, and the plates are engraved with complex corrugated flow channels. Cold and hot liquids flow in opposite directions in the adjacent plate channels, and the heat can easily pass through the thin plates and transfer from the hot side to the cold side.

Its core mission: isolation and heat transfer

One side (internal circulation): flows with clean internal coolant, responsible for taking away the heat of the equipment.

Secondary side (external circulation): flows with external cooling water and is responsible for the final removal of heat.

The plate heat exchanger acts like a dutiful "goalkeeper", allowing the two liquids to "transfer heat across the air" and physically completely isolate them, thus perfectly protecting the internal precision equipment and the clean liquid cooling circuit.

Four advantages of plate heat exchanger:

Efficient and compact: The corrugated design generates turbulence, high heat transfer efficiency, but small volume, very suitable for space tight scenarios.

Safety isolation: Eliminating external dirty water from internal systems is the cornerstone of system reliability.

Precise temperature control: The temperature of the coolant supplied to the equipment can be precisely controlled by adjusting the external water quantity.

Easy maintenance: can be easily opened for cleaning and maintenance.

II. The bottom line of life: cleanliness testing, no mistakes

If plate heat exchangers are the "gatekeepers", then cleanliness is the bottom line that this gatekeeper must adhere to. Any small oil stains, metal chips, particles may be the "invisible bomb" in the system, leading to:

Heat exchange efficiency decreases: dirt is like a "cotton jacket" that wraps around the plate and hinders heat transfer, resulting in a rise in equipment temperature.

Flow channel blockage: particle accumulation, increasing water flow resistance, increasing pump load, or even completely blocked.

Corrosion and leakage: Contaminants can accelerate system corrosion and eventually lead to leakage, with catastrophic consequences.

Therefore, cleanliness detection must run through the "life" of plate heat exchanger.

1. Comprehensive physical examination before new equipment is put into service

A brand-new heat exchanger may carry "native pollution" such as processed oil and metal chips when it leaves the factory. Before being connected to the system, it must undergo a strict "purification ceremony".

Scientific washing and data speak:

Establish an independent recirculation loop and perform a "violent flush" with high-flow deionized water.

At the outlet, a liquid particle counter monitors in real time, and only when the number of particles is stable and reduced below the standard (such as ISO cleanliness level) is it considered qualified.

The filter membrane sampling method can also be used. After filtering the water sample, the weight is weighed and observed under the microscope to quantify the cleaning degree.

2. Regular checkups and health care during operation

Even if it is very clean at the beginning, the secondary side is easy to form scale and breed bacteria and algae during long-term operation. It is necessary to regularly monitor its "health indicators".

Performance monitoring (indirect judgment):

Temperature measurement: under a fixed flow rate, if the temperature difference between the inlet and outlet is small, it means that it is "feverish" and the heat transfer efficiency decreases.

Blood pressure measurement: If the pressure drop through it is large, it indicates that the blood vessel (flow channel) may be blocked.

Direct inspection and maintenance:

Regular "intestinal cleansing": depending on the operation, disassemble it regularly and give it a thorough "bath" with a brush, high-pressure water gun or chemical cleaning agent.

Water quality testing: The secondary side cooling water is tested regularly to monitor its hardness, pH value, conductivity, etc., to prevent scaling and corrosion from the source.

III. Summary

In today's pursuit of high computing power and high density, the importance of liquid cooling system is self-evident. The plate heat exchanger as its core heat exchange component, and cleanliness as its lifeline, together constitute a solid guarantee for the stable operation of the system.

Suggestions for operations engineers:

Establish a strict cleanliness control system, from the "first gate" of new equipment acceptance to regular monitoring and maintenance during operation, forming a closed-loop management. Never lose the big picture because of a small one, let a small pollutant destroy the entire expensive liquid cooling system.