What is the Difference Between Air Conditioning Chillers and Process Chillers?
Process chillers are made to operate at different temperatures with different fluids and different flow rates. These have the ability to work with multiple pumps and multiple cooling circuits. The systems typically includes a pump and reservoir designed by the manufacturer, which are integrated into the chiller design. The energy efficiency rating follows Non-Standard Part Load Value (NPLV) rules.
Air conditioning chillers are made to run at one temperature, one flow rate and one fluid type. Typically, the design is a pressurized system and the pump and reservoir are designed and sourced by the installing contractor. The energy efficiency rating follows Integrated Part Load Value (IPLV) rules.
Generally this is done by circulating coolant liquid usually water mixed with an antifreeze solution through special cooling passages. Some engines are cooled by air flowing over finned cylinder casings.
A car engine produces a lot of heat when it is running, and must be cooled continuously to avoid engine damage.
A water-cooled engine block and cylinder head have interconnected coolant channels running through them. At the top of the cylinder head all the channels converge to a single outlet.
A pump , driven by a pulley and belt from the crankshaft , drives hot coolant out of the engine to the radiator , which is a form of heat exchanger .
Unwanted heat is passed from the radiator into the air stream, and the cooled liquid then returns to an inlet at the bottom of the block and flows back into the channels again.
Usually the pump sends coolant up through the engine and down through the radiator, taking advantage of the fact that hot water expands, becomes lighter and rises above cool water when heated. Its natural tendency is to flow upwards, and the pump assists circulation.
The radiator is linked to the engine by rubber hoses , and has a top and bottom tank connected by a core a bank of many fine tubes.
The tubes pass through holes in a stack of thin sheet-metal fins, so that the core has a very large surface area and can lose heat rapidly to the cooler air passing through it.
On older cars the tubes run vertically, but modern, low-fronted cars have crossflow radiators with tubes that run from side to side.
In an engine at its ordinary working temperature, the coolant is only just below normal boiling point.
The risk of boiling is avoided by increasing the pressure in the system, which raises the boiling point.
The extra pressure is limited by the radiator cap, which has a pressure valve in it. Excessive pressure opens the valve, and coolant flows out through an overflow pipe.
In a cooling system of this type there is a continual slight loss of coolant if the engine runs very hot. The system needs topping up from time to time.
Later cars have a sealed system in which any overflow goes into an expansion tank , from which it is sucked back into the engine when the remaining liquid cools.