Although this sounds incredible, the simple truth is that 100% of the electrical energy input into an air compressor is turned into heat during the process of compression, generally this heat energy isn’t recovered and therefore goes to waste.
The major proportion of the energy recoverable as heat is theoretically 96% of the overall electrical consumption. In a fully encapsulated oil cooled screw compressor even the losses from the electric motor can be recovered as hot air. It consists of heat dissipated in the oil cooler (78%), the after cooler (13%) and the heat radiated by the drive motor (5%). The remaining 4% of heat cannot be recovered as 2% radiates through the canopy and the other 2% remains in the compressed air.
The two most common ways to recover the wasted heat is either using the exhaust air as direct Space Heating (ducted away) or by the compressor cooling oil passing through a Heat Exchanger (ELGi Heat Recovery Unit) can heat water.
Space Heating
The simplest and most direct method of recovering the heat generated by a screw compressor is by direct utilisation of the heated air being ducted away to be used for space heating of warehouses and workshops (winter). When the heated is not needed (summer) a manual or automatic flap or louvre discharges it into the open. The louvres can also be thermostatically regulated to maintain a constant set temperature (e.g. Plant Room).
Heat Exchanger
If an ELGi Heat Recovery Unit (heat exchanger) is installed in the air-end cooling oil circuit, it is possible to generate hot water for various purposes with an air or water-cooled screw compressor. The use of the hot water will depend on its intended purpose e.g. Heating, Shower & Wash Water or use in production and cleaning processes. With the potential energy savings available from this system it is thought that from the capacity of compressor packages from 5.5kW and above the additional costs for the Heat Exchanger amortise within a very short time.
