Many considerations go into selecting a cooling system for the induction heating process, including cost, available space, existing utilities, power and water use, equipment location, freeze-up potential, reliability, and maintenance.
Types of Cooling Systems
A unique closed-loop cooling system is required for induction cooling, and all components are made of nonferrous materials (stainless steel, plastic, PVC, bronze, or a nonconductive pipe).
More complex systems will monitor the conductivity and can incorporate filtration and mixed-bed deionizers for polishing water. Smaller pumped machines typically use a heat exchanger with water-to-water plates and a chiller that chills air at the point of service. Larger induction cooling installations include:
- Open-air evaporative towers
- Air-cooled heat exchangers (dry coolers)
- Closed-loop chillers
- Hybrid cooling systems using either a closed-loop tower with free-coolers or a chiller/free-cooler combo for reduced power and water use
What do we recommend?
We recommend one of three cooling systems depending on your space requirements, industrial needs, and budget:
- Simple Water-Cooling System
The simplest water cooling system for induction heating is a tank of water with a pump to move the water around. It’s incredibly easy to set up, and has a very small investment cost. This makes it perfect for customers with smaller budgets who still want to get great results from their induction heater.
- Closed Water-Cooling Tower.
The closed water-cooling tower is ideal for customers who need to keep their footprint as small as possible while still keeping their systems cool enough to function properly. It’s less expensive than a chiller but works just as well. Most critically, it has a much smaller footprint than the suggested water-cooling system of the tank and water pump. For customers with sufficient budget, this can be selected over a chiller or an open loop cooling tower which are more expensive.
You can fine tune the heat transfer between the cooling and interior water. For example, coolant temperature in a closed loop system is determined by the designed near-air temperature of the heat exchanger and the maximum cooling input temperature of the liquid doing the cooling. Then, the mixture flows into the heat exchanger, where the heat transfers to another cooling fluid, such as glycol/water.
- Industrial Chillers.
An industrial chiller is a cooling system that reduces temperatures in machines, industrial spaces, and process liquids, removing heat from a system and moving it elsewhere. It is expensive but has a very small footprint and is suitable for customers with insufficient laboratory or factory space.
Water chiller types are water and air-cooled, divided into vapor-absorption and vapor-compression chillers, which use different methods of extracting collected heat. A chiller uses a vapor-compression mechanical cooling system, which is connected to a processing water system via a device called an evaporator. A vapor compression chiller uses a refrigerant to absorb heat from the space and return it to the evaporator, which takes away heat, using fans for air-cooled chillers or water for water-cooled ones.
Water Use
Coolant water, which circulates throughout most of the induction system, is exposed to EMFs and high-voltage potentials, resulting in areas ripe for erosion and corrosion.
Poor water quality quickly leads to blocked cooling channels, causing the device to operate hotter, causing arcing, and high cost in replacement. Therefore, you must use clean, low-conductivity water and check its quality regularly. Customers often add bottle-distilled water to smaller cooling systems and periodically replace it to ensure it is clean. In addition, customers can use either demi-ionized or reverse-osmosis (RO) water for larger installations, treated with a corrosion inhibitor or a corrosion-reducing glycol.
Untreated water, either straight deionized water or water with no minerals, will act as an aggressive scavenger and strip the metals from the device. Therefore, the use of municipal or well water must also be avoided.
Plate Exchanger
When the pipes are arranged in counterflow, a plate heat exchanger is highly efficient for transferring heat. A welded plate heat exchanger is a lower-cost alternative typically used in lower-flow applications, typically replaced rather than cleaned.
An air-cooled chiller uses mechanical refrigeration loops to dump heat from induction water into the ambient air. All the heat generated by the conduction process has to go through the cooling coils before being rejected back into the ambient air.
The cooler must be precisely sized. In addition, it is best to size the chiller to operate over long periods to allow good circulation in the cooling cycle and ensure that the chiller achieves stable operational temperatures.
Chillers require regular maintenance and replacement parts, which can both be costly.
As a result, good monitoring and treatment programs must be implemented to monitor the water quality and maintain good corrosion controls to protect the equipment and the pipe systems. In addition, water treatment and flushing (drain) is required to prevent corrosion, scale, and organisms from developing within the system.
Low-power systems typically need a compact air-to-water heat exchanger, whereas a higher-power system might need a larger air-to-water or cooling exchanger. Smaller conduction machines typically use plate-type heat exchangers with a water-to-water arrangement and point-of-service air-cooled chillers.
The closed-loop cooling system has moderate capital costs, low maintenance, and requires no makeup water or ongoing chemical treatments.
A smart controller on your cooling system can be used to set your water’s minimum and maximum temperature, complete with alarms.