Energy Efficiency in Air Cooled Chillers

An air cooled water chiller removes heat from water or inconsistent process fluid by use of a refrigeration system that wherefore dissipates that same heat into the air. The energy efficiency is habituated by the chiller COP.

The chiller operates by using the nickels of state of a refrigerant gas which when forced through an breach at formidable pressure changes state from a liquid to a gas, absorbing heat through the chiller evaporator heat exchanger. This cold expanded gas then travels to the chiller refrigeration compressor where it is compressed into a hot, rigid gas and pumped to the chiller condenser. The venue that the compressor can examine, the refrigeration gas used, and the operating conditions determine how extremely heat is removed.

At the air cooled chiller condenser the refrigerant is forced by the compressor through smaller copper tubes which have thin aluminum fins mechanically contracted to them. Ambient air is whence forced through the condenser coil by the chiller fans. This causes the hot refrigerant gas to condense matter a serum, changing state, and releasing the heat that the gas mellow at the chiller evaporator. The waste heat is then carried away concern the ambient air by the fans. The liquid is then forced concluded the orifice and the process starts again.

The heart of the chiller is the refrigeration compressor. This is a pump that uses electrical energy to pump refrigerant around the system. Depending on the application like size or operating temperature, a different compressor pumping technology is used. Smaller chillers use refrigeration compressors like rotary compressors, scroll compressors, and reciprocating compressors. Improved chillers use refrigeration compressor like reciprocating compressors, screw compressors, absorption compressors, and centrifugal compressors.

Each type of refrigeration compressor can operate more or less efficiently in the air cooled water chiller depending on the water or glycol outlet temperature necessary, the ambient air temperature conditions and the chiller refrigerant used.

The efficiency of the chiller compressor is given by the COP or Coefficient of Performance which is the ratio of kW of heat removed to kW electrical input main. The higher the chiller Fetch is, the better the energy efficiency. For precedent a Glean of 3 means that for every 1 kW of electrical input, 3kW of heat is invalidating from the water. A chiller COP of 5 means that for every 1kW of electrical energy input, 5kW of heat energy is removed from the water.

Typically chiller Salvage cede vary because follows:

1. Holding the chiller condensing temperature constant: a lower chiller evaporating temperature will use more electrical power per kW heat opposing and the chiller COP will be worse, stage a higher chiller evaporating temperature will use less electrical power per kW of heat removed and the Gain will be higher.

2. Takings chiller evaporating temperature pat: a higher chiller condensing temperature will have a worse chiller COP that having a inferior chiller condensing temperature.

A customer ' s process cooling requirement consign determine the operating temperature for the air cooled water chiller. For example an air conditioning chiller will require water typically at 7 deg C outlet from the chiller evaporator and 12 deg C return. This would require a chiller refrigerant like R407C which is stunning for ambient air environments of flowering to 45 deg C.

Where a higher chiller water outlet temperature is required a chiller refrigerant gas like R134a would be acceptable and this has the farther worth of allowing the chiller to govern in conspicuously in addition ambient conditions - for example - chillers in the Middle East and chillers in Australia - remote locations like mine sites - are often located where the ambient air can be 50 deg C or above.

Daniel Rollston is the Colloquial Manager for the Australian chiller manufacturer Capstone Matsu Chilling Systems. The Company manufactures and distributes water chillers Australia wide and also commission and helping hand 2kW to 1200kW chillers Australia wide and throughout the Middle East.