トップページ | This machine was noisy, inefficient and would prove to be difficult »

2019年6月 4日 (火)

This would require a chiller refrigerant like R407C

This would require a chiller refrigerant like R407C which is fine for ambient
air environments of up to 45 deg C.
2.

A customers process cooling
requirement will determine the operating temperature for the air cooled water
chiller. For example a COP of 3 means that for every 1 kW of electrical input,
3kW of heat is removed from the water. An air cooled water chiller removes heat
from water or other process fluid by use of a refrigeration system that then
dissipates that same heat into the air.

The chiller operates by using the
change of state of a refrigerant gas which when forced through an orifice at
high pressure changes state from a liquid to a gas, absorbing heat through the
chiller evaporator heat exchanger. This is a pump that uses electrical energy to
pump refrigerant around the system.

At the air cooled chiller condenser
the refrigerant is forced by the compressor through smaller copper tubes which
have thin aluminum fins mechanically bonded to them. The volume that the
compressor can pump, the refrigeration gas used, and the operating conditions
determine how much heat is removed. The higher the chiller COP is, the better
the energy efficiency. This causes the hot refrigerant gas to condense into a
liquid, changing state, and releasing the heat that the gas collected at the
chiller evaporator.

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 required, the ambient air temperature conditions
and the chiller refrigerant used. A chiller COP of 5 means that for every 1kW of
electrical energy input, 5kW of heat energy is removed from the water. Smaller
chillers use refrigeration compressors like rotary compressors, scroll
compressors, and reciprocating compressors. Depending on the application like
size or
Serial Air-cooled Condenser
operating temperature, a different compressor
pumping technology is used. The waste heat is then carried away into the ambient
air by the fans.

Where a higher chiller water outlet temperature is
required a chiller refrigerant gas like R134a would be acceptable and this has
the added benefit of allowing the chiller to operate in much higher 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.

Typically chiller COP will vary as follows:
1.
Ambient air is then forced through the condenser coil by the chiller fans..
Holding chiller evaporating temperature constant: a higher chiller condensing
temperature will have a worse chiller COP that having a lower chiller condensing
temperature. The liquid is then forced through the orifice and the process
starts again.

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 required. This cold expanded gas then travels to the chiller
refrigeration compressor where it is compressed into a hot, dense gas and pumped
to the chiller condenser. For example an air conditioning chiller will require
water typically at 7 deg C outlet from the chiller evaporator and 12 deg C
return. The energy efficiency is given by the chiller COP. Holding the chiller
condensing temperature constant: a lower chiller evaporating temperature will
use more electrical power per kW heat removed and the chiller COP will be worse,
while a higher chiller evaporating temperature will use less electrical power
per kW of heat removed and the COP will be higher. Larger chillers use
refrigeration compressor like reciprocating compressors, screw compressors,
absorption compressors, and centrifugal compressors.

The heart of the
chiller is the refrigeration compressor

トップページ | This machine was noisy, inefficient and would prove to be difficult »

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トップページ | This machine was noisy, inefficient and would prove to be difficult »

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