Industrial Coating and Coil - Energy Conservation


A Rahn Industries Company

Energy Conservation

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Air-conditioning systems are big energy consumers. Especially the compressor of a cooling installation uses more energy than you might think. Therefore, it is very important that this compressor operate at optimal conditions at the highest efficiency possible. One of the most important parameters will be the condensing temperature of the cooling system. A low condensing temperature will result in a higher efficiency of the compressor.

Air-cooled condensers are very sensitive to corrosion which has a great impact on their performance. A corroded air-cooled condenser causes a higher condensing temperature resulting in higher energy consumption of the system.

The Blygold corrosion protection system will ensure the performance of the condenser over time, and stop the increase of energy consumption. This way a Blygold treatment can be regained within one year.

Impact of corrosion on air-cooled condensers

Impact of Corrosion Regular air-cooled condensers are made of aluminum fins onto copper tubes. Due to this combination, galvanic corrosion will occur when an electrolyte is present (salt in water). The aluminum will dissolve around the copper tube and there will be a bad heat transfer from copper to aluminum. This results in poor performance (exchange heat) of the coil.

Galvanic corrosion in a coil
Corrosion on aluminum fins causes a rough surface. Due to this rough surface dirt will easily adhere to the fin resulting in an isolation layer around the fin. This dirt layer will reduce heat transfer but also reduce airflow through the coil.

Practical example of two chillers at the same location with and without treatment:


100 RT chiller without Blygold treatment		100 RT chiller with Blygold treatment

Condensing temperature:	56ºC (132ºF)	Condensing temperature:	48ºC (118ºF)
Energy consumption:	119 kW	Energy consumption:	113.4 kW
Energy consumption:	2000 hours	Energy consumption:	1834 hours
Power consumption/yr:	238000 kWH	Power consumption/yr:	207975 kWH

Energy savings: (238000-207975 = 30024 kWh = 30024*0.125$) = $3753.00
Total Energy Saving: $3,753 per year

Impact at the cooling process

Regular air-cooled condensers are made of aluminum fins onto copper tubes. Due to this combination, galvanic corrosion will occur when an electrolyte is present (salt in water). The aluminum will dissolve around the copper tube and there will be a bad heat transfer from copper to aluminum. This results in a bad performance (exchange heat) of the coil.

Galvanic corrosion in a coil
Corrosion on aluminum fins causes a rough surface. Due to this rough surface dirt will easily adhere to the fin resulting in an isolation layer around the fin. This dirt layer will reduce heat transfer but also reduce airflow through the coil. Coil performs lower.

Imoact at the cooling Process
Corrosion will have a huge impact on the energy consumption of your cooling machine. A standard simple cooling process contains 4 steps.

1: Compression the compressor increases the refrigerant gas pressure from low P e1/2 to high P e1

2: Condensing, in the condenser the refrigerant gas condenses from gas to liquid by transferring heat.

3: Expansion, in the expansion valve the liquid refrigerant is throttled from high pressure (P e1) to low pressure (P e1/2) without change in enthalpy.

4: Evaporation, the liquid refrigerant at low pressure starts to evaporate in the evaporator by extracting heat from the environment.

The logP-h diagram shows the cooling process. In this graph the cooling capacity is given by the ?h of 3 and 4, the compressor power input is given by ?h of 4 and 1. If the condensing temperature rises, due to the environment or corrosion, the cooling process will follow the red line in the log P-h diagram with step 1'-2', 2'-3', 3'-4, 4-1'.