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Waste water heat recovery

Sustainable alternative to conventional systems
Waste water heat recovery

Suitable for public swimming pools and fish farms.


Heat recovery

Many applications use water, requiring a prescribed amount of water to be changed every hour. Examples are public swimming pools (replenishment water) and fish farms. It is important that the fresh water is at the right temperature when it enters the system. In practice, the fresh water often requires heating, involving high energy consumption.

The HydroX is a water-to-water heat exchanger that recovers heat from waste water. This heat can in turn be used to heat up the fresh water supplied,  providing a sustainable alternative to conventional systems.


Operation

Both the waste water and the fresh water are passed through the HydroX. The relatively warm waste water will cool down and the colder fresh water will heat up. After that, the fresh water can be brought to the desired temperature, possibly using the existing installation.

 

Minimised energy consumption

Because the water has been preheated in the HydroX to a major extent, the energy consumption of the existing installation will be significantly lower. In some cases the fresh water preheated in the HydroX can be used directly, making energy consumption for heating a thing of the past. And in situations where the desired temperature is below the temperature of the fresh water supplied, the HydroX can also be used in the same way to cool the fresh water.

 

Benefits of HydroX

 

Calculation of payback time with Exegy HydroCalc

The calculation example below shows how the Exegy HydroCalc can be used to give a quick indication of the payback time.

Amount of water to be changed: 5m³/h
Current temperature of the fresh water: 14°C
Supply water temperature desired: 30°C

Here, 30 kW can be recovered and reused to preheat the fresh water and raise its temperature by 5 °C.

Per day: 30 kW x 24 hours x €0,09 per kWh x 1/3* =  € 22
Per year: €22 x 365 = € 8000
Annual energy costs for a heat pump: € 500
Annual savings: € 7500

* In this example, we have compared this situation with the HydroX to a situation in which the heat - which is now being recovered with the HydroX - should have been generated using a heat pump with a COP of 3.  This explains the factor 1/3 in the calculation example.


 

HydroX in Cascade

The modular construction of HydroX water-to-water heat exchangers enables you to cascade multiple exchangers to recover even more energy and preheat the water even more.