Air Compressor Analysis

[mahoneg]

I am working at a facility that currently uses a 75 hp compressor to meet its plant demand. The company is considering replacing the compressor with a VFD and installing ductwork to direct the waste heat to another room in the facility. I need help determining the amount of energy that is being lost via the compressor exhaust. I have data for the exit temp, pressure and percent capacity of the current compressor. Can someone help me get started? Thanks in advance.

 

[PEDARRIN2]

Compressed Air Challenge (

http://www.compressedairchallenge.org/)

has some articles on heat recovery from air compressors.

Also, Compressed Air Best Practices Magazine (Nov, 2012) has a good article on this.

Try those.

 

[hendrik78]

I assume you're talking about an air cooled compressor? In that case, at least 90% of the input power of the compressor will be transformed into heat and removed via the cooling fan. Ducting that hot air is an excellent heat recovery project.

 

[chicopee]

Heat recovery as mentioned above is fine, however, there may be an oil odor with the heat recovery system. If heat recovery is for an industrial plant where there is a large working space that odor should not be a problem, however if it is for offices where the physical spaces are smaller than the odor may be offensive.

 

[semago]

Do you have data on the ventilation units that are supplying and exhausting the compressor room right now?

If you have :

1- Supply air flow and temperature (T1) for the room. Check the informations of the supply fan if there is one. Air may be supplied by other sections of the building, then T1 will be the average temperature in rooms around the compressor room.
2- Exhaust air flow and temperature (T2) for the room (check the informations of the exhaust fan).

Note: Supply and exhaust will probably have the same air flow in ACFM, but will be of different temperatures. Assume it's the same flow for both fans (CFM)

Given those numbers, you will approximate the heat lost by your compressor in the room :

E = 1,08 X CFM X (T2 - T1)

That energy can be recovered in many ways.