Common Types of Cooling Systems and Their Applications in Enclosure Cooling

Summary

As high-power industrial machines and their controls function, they generate excessive heat. If not controlled, that heat can hinder the machine’s performance and become a safety hazard. 

Enclosure cooling systems give equipment, prone to excessive working heat, the ability to control the excess waste heat, discarding it as it occurs. 

Regardless of the type of cooling system you utilize, enclosure cooling will benefit your machine’s

• Performance reliability: too much heat can cause slowed system speeds or malfunctions. Proper enclosure cooling can keep the climate controlled to ensure peak performance. 
• Lifespan: when exposed to temperatures above the manufacturer’s maximum rating, the electronics are at risk for premature failure. Controlling the excess heat leads to greater life expectancy.
• Safety: high temperatures pose electrical hazards, putting machine operators at risk of fires or explosions. Enclosure cooling reduces the likelihood of electrical explosions by controlling the system’s climate. 

Four types of enclosure cooling systems

There are plenty of types of cooling systems on the market, so narrowing down your options can be difficult. Below are 4 reputable enclosure coolers recommended by ACT. 

1. Heat sink coolers (air cooling)
Using air-to-air cooling technology, heat sink coolers (HSC) achieve heat transfer through air circulation. As the air moves throughout the enclosure cabinet, the internal heat sink collects the excess heat. Here, the heat is transferred to a mounting plate and then discarded through the opposite, external heat sink fan. 

This technology works because heat sinks are made of thermally conductive materials like copper or aluminum. When added to a machine, they increase the surface area of the cabinet so they can efficiently collect heat waste to transfer to a mirrored mounting plate. 

HSCs utilize above-ambient heat exchange. When used indoors (such as in a manufacturing plant), this removes the need to chill the air to lower operating temperatures, keeping conditions comfortable for warehouse workers. 

When used outdoors, HSCs remove the impossibility of controlling the ambient temperature while keeping the electronics operating at a safe temperature.

Their price-to-performance ratio makes these types of cooling systems a highly economical option to rise above ambient temperatures. If you’re tight on space, this family of units could be your winner!

2. Heat pipe coolers (evaporative cooling)
Unlike air cooling, evaporative cooling systems utilize a small amount of working fluid to achieve heat transfer. For instance, heat pipe coolers (HPCs) use working fluid to distribute heat (almost) equally throughout the structure. 

When the heat enters the evaporator, the fluid boils and pushes the vapor to the cooler region (called the condenser) on the opposite end. 

At the condenser, the fluid discards its latent heat, returning the vapor to its liquid state, and is pushed back to the evaporator. The flow between each state is continuous.

HPCs are a compact option that can be used for indoor or outdoor enclosure systems. If the surface area on your enclosure is limited, HPCs can be easily mounted to the top of your cabinet. The only limitation of these types of cooling systems is that they can only be used in sub-ambient temperatures.



3. Vapor compression coolers (refrigeration cooling)
Working in a closed-loop system, vapor compression coolers (VCCs) utilize the four components of the refrigeration cooling cycle: the compressor, condenser, expansion valve and evaporator.

The cycle begins at the compressor, where the low-temperature refrigerant vapor enters the system. Here, compression increases the temperature and pressure of the refrigerant pushing it to the condenser.

When the high-pressure refrigerant reaches the condenser, heat exchange occurs and is dissipated through water or air. As the heat exchange is conducted, the refrigerant gives up latent heat, turning it into a hot, liquid state.

In its liquid state, the refrigeration enters the expansion valve where it expands, subsequently decreasing in temperature and pressure. With its temperature low, the two-phase fluid enters the evaporator. When exposed to the heat source, the fluid vaporizes and reenters the compressor, completing (and repeating) the cycle.

The way VCCs are applied will depend on whether they’re made to cool air or liquid. Liquid cooling is often used in the medical industry for cooling lasers and medical devices. Air coolers can be applied to a variety of industries using electronic enclosures, indoor and outdoor power electronics, solar farms, indoor farming, data centers and more.

4. Thermoelectric coolers (solid state cooling)
Thermoelectric coolers (TEC), similar to heat sinks, use solid-state cooling. This means there are no compressors, refrigerants, or circulating liquids required for heat transfer to occur.  

Instead, TECs utilize the Peltier Effect, which conducts heat from one side of the plate to the other when a direct current (DC) is applied. 

If you’re looking for a quiet, lower-power solution, TECs are a desirable option. They can operate reliably for 24 hours a day, seven days a week, and in the toughest environments. 

They are suitable options for smaller cabinets in need of sub-ambient cooling, such as trackside rail controls. 

Cooling system selection criteria

Deciding on the type of cooling system your enclosure needs will depend on your thermal load, which also depends on your ambient temperature.

The word “ambient” refers to the immediate surroundings of something. In the context of heat exchange systems, “ambient” describes the temperature of the room surrounding the electronics or machinery.

Above-ambient vs. below-ambient heat exchangers

Ambient exchangers are needed when the temperature inside of the cabinet is hotter than the outside. Heat sink coolers and heat pipe coolers are suitable enclosure cooling options to use to rise above ambient temperatures. 

Conversely, below-ambient exchangers are used when the temperature inside the enclosure must be cooled way below the ambient temperature. Cooling systems that operate best for sub-ambient heat exchange include vapor compression coolers and thermoelectric coolers.