AIRWATT External heat recovery units

Classical systems of the screw compressor have a regulated air cooling of the lubricating oil, which means that the excess heat is discharged into the ambient by the fan. In this way, the heat is completely lost. External heat recovery unit AirWatt is designed to efficiently exploit the waste heat, generated during air compression in rotary screw compressors. Sometimes this represents more than 70% of the energy consumed by the rotary screw compressor for the operation. This heat can then be used to heat domestic water or for heating, at almost no additional costs. This does not only help save money but is also environmentally friendly. The AIRWATT External heat recovery unit has two separate piping systems with counterflow. Energy exchange from a compressor to sanitary water occurs in a plate heat exchanger, where compressor oil and sanitary water meets. The unit is controlled by a thermostatic valve, preventing the compressor system from getting too cold and damaging.

Characteristics

Heat Capacity: 5,6 to 236 kW

Compressor  capacity: 7,5 to 315 kW

Heat recovery

There are four connections on the back side of device. Two are connected to compressor oil circuit, the other two are for water circuit. When compressor is in operation, compressor oil constantly flows through AirWatt heat exchanger oil piping and plate heat exchanger. Water does not start to flow through thermostatic valve, until oil temperature reaches the set value on the valve. When oil temperature reaches desired value, thermostatic valve opens water flow through plate heat exchanger. Heat is extracted from oil and its temperature drops. Water gains heat. The lower the water flow, the higher its temperature at outlet gets.

Investment payback period

Materials

Housing	Steel sheet metal
Outside protection	Powder paint coated (Epoxy-polyester base)
Heat exchanger	Stainless steel
Pipes	Stainless steel
Connections	Brass, copper, stainless steel
Feet	NBR

Applications

• heat recovery in oil lubricated rotary screw compressors

Maintenance

Once per month make a visual check of EXTERNAL HEAT RECOVERY UNIT and make sure there is no visual damage or leaking. Regular cleaning will prevent thicker sediment and debris on piping wall and inside plate heat exchanger.

Recommended cleaning intervals:
- Every 6 months (very dirty and mineral rich water)
- Every 12 months (moderately dirty water, surface water)
- Every 3 years (clean water)
For cleaning oil sediments and grease it is recommended to use paraffin, for cleaning of limestone use formic acid, acetic acid or citric acid.

Technical data

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