Industrial Process Chillers

A chiller is a cooling system that removes heat from one element (water) and moves that heat into another element (ambient air or water). The Chiller is very similar to an air conditioning system in that it is compressor based but it cools liquid while an air conditioning system cools air. Other components are a reservoir, re-circulating pump, evaporator, condenser and a temperature controller. The cooling fluid used is usually a mix of ethylene glycol and water.

• A basic chiller has a water circuit and a refrigeration circuit. A pump circulates water from a holding tank to an evaporator that cools the water by transferring heat to a refrigerant, the water then moves on to the process then back to the tank, completing the water circuit. In the independent refrigeration circuit, the evaporator that cools the water of the water circuit uses the heat from the water to boil the refrigerant converting it to a gas. A compressor increases the pressure of that gas to approximately 220 p.s.i. for freon refrigerant. The gas under pressure moves into the condenser and converts back to a liquid. Cooling for the gas comes either from ambient air at 95°F or from cooling tower water at 85°F.
• Industrial chillers work in the same way. Water is pumped to the chiller at 60°F and cooled to 50°F, with a water and glycol solution, temperatures of 20°F are attainable. The heat is removed from the system, either with a plant cooling tower system, an outdoor air condenser, or with ambient plant air.

There are six systems for cooling that are incorporated into chillers.

1. Portable Chillers are a single pump chiller, supplied with either air or water cooled condensers and are used to cool one or two machines with the process water flow limited to 2.4 g.p.m. / ton.
2. A Packaged Chiller System is a two pump system with one pump for the evaporator and the other for the varying process. The condensers are either air cooled or water cooled with no process water flow restriction.
3. A Central Chilling System has one or more central chillers connected to a common two pump tank set. Stand by pumps and chillers can be added to increase cooling capacity.
4. A Central Cooling Tower System has one or more cooling towers connected to a common two pump tank set. This system may be expanded by adding tanks, chillers and towers. Chillers are used to cool any machine or process that operates at 60°F or lower. A cooling tower can be used to cool any machine or process that operates at 85°F or higher.
5. Air Cooled Chillers absorb heat from process water then transfer the heat to the surrounding air. Air Cooled Chillers are generally used in applications where the additional heat they discharge is not a factor. They require less maintenance than Water Cooled units and eliminate the need for a cooling tower and condense water pump. They generally consume approximately 10% more power than a water-cooled unit as a wet surface will transfer heat better than a dry surface.
6. Water Cooled Chillers absorb heat from process water and transfer it to a separate water source such as a cooling tower, river or pond. They are generally used for large capacity applications, where the heat generated by an air cooled chiller creates a problem. They are also considered when a cooling tower is already in place, or where the customer requires optimum efficiency of power consumption. Water Cooled Chillers require condenser water treatment to eliminate mineral buildup. Mineral deposits create poor heat transfer situations reducing the efficiency of the unit.

Applications

Chillers are used to cool any machine or process that operates at 60 F or lower. A cooling tower can be used to cool any machine or process that operates at 85 F or higher. Some of the more common applications include:

• Plastics Industry uses chilling systems to cool the hot plastic that is injected, blown, extruded or stamped. A chilling system can also cool down the equipment that is used to create plastic products; hydraulics of the molding machine, gear box and barrel of the extruder.
• Printing Industry uses chillers not only to remove the heat generated by the friction of the printing rollers, but to cool down the paper after it comes out of the ink drying ovens in the process.
• Laser Cutting Industry and the light projection industry uses chilling systems to cool down the lasers and power supplies.
• Rubber Industry uses chillers to cool the multi-zone water temperature control units of the rubber extruder barrel, cool the rubber mill, calendars and bambury mixers used to make rubber.
• Beverage Industry chillers remove the heat gained from the process during mixing, cooking, or after pasteurizing the product.
• Medical Equipment for magnetic resonance imaging, scanning, blood cooling and laboratory testing use chillers to remove all the heat generated.