Multipurpose sewer pipe with a "slinky" heat pipe exchanger

Feb 20, 2007

A new sewer pipe construction with an outside attached and into the pipe wall embedded spiral heat pipe exchanger for additional utilization of the surrounding ground heat and its storage capabilities and the wastewater heat as alternative heat sources for geothermal heat pump systems.

"Slinky" is the term commonly used rather than the imposing scientific name - curtate cycloid.
When used with geothermal heat pump systems, the Slinky application is one option, and has varies configurations, but the most known construction is a flattened, overlapped plastic pipe circular coiled ground loop heat exchanger be installed horizontally at the bottom of a three-foot wide trench or vertically in a narrower trench, which is back-filled afterwards. Its advantage is that it concentrates the heat transfer surface into a smaller volume, requiring less land area and shorter trenching, and has significant reduction in first costs. But the disadvantage still is that it can only be used for shallow ground heat recovery under open land, but not for ground heat storage, because the heat capacity of the shallow ground vary depending on seasonal solar, rain, and temperature intensities. So generally heat storage is an essential part of a very broad range of renewable & energy efficiency applications, and is an enabling technology, without it, alternative heating would not be possible.

New Solution:
Orange Depot & Exchange Systems has developed a multipurpose (hybrid-) sewer pipe construction with an outside attached and into the pipe wall embedded spiral heat pipe exchanger for additional utilization of the surrounding ground heat and its storage capabilities and the wastewater heat as alternative heat sources for geothermal heat pump systems. See picture below.
This hybrid sewer pipe is a simple and low cost construction based on conventional product parts, and can be laid in a familiar way. Beside its primary task of wastewater collection and transport it utilizes additionally the wastewater heat, the ground heat, and the ground heat storage volume around the sewer pipe mostly positioned under city streets, walkways and squares in synergetic combination.
The additional use of the waste heat from sewer collection systems as an alternative heat source makes a lot of sense from an ecological and economical point of view.

The temperature of the raw wastewater in thousands of kilometres of municipal sewer lines is on average 12-16°C due to frequently incoming wastewater from urban and industrial processes. It can be up to 20°C or more depending on the geographical location of the particular country. The wastewater collection system itself is a huge horizontal shallow ground heat exchanger too embedded in the ground with a perfect infrastructure for reaching every resident over a short distance.
Japanese estimates indicated that 40% of the waste heat discharged by urban communities is carried away in the sewage. Theoretically, if only the entire wastewater for example in Germany, estimated at approximately 11 Billion m3, would be cooled down only by 5° C a heat amount of 65 billion MWh could be drawn. That means a reduction of 5,59 billion tonnes of fossil fuels and 11 billion tonnes of CO2–Emission.

Sewer collection systems therefore contain a large amount of eco-heat-energy with a huge future perspective for every community in the world. No doubt this energy is a perfect heat source for modern heat pump systems preferably be used for district and single house heating & cooling alternative to or in combination with conventional heating systems. It has a far higher temperature level than the ground heat, but the disadvantage is that wastewater is finally not an absolute sustainable heat source too, because its flow volume and temperature depends on seasonal and technical running influences, and how many inhabitants are connected. So bigger sewers carry waste water at any time but with different volumes and temperatures during the day and season, and smaller sewers have sometimes wastewater and sometimes not.

So regarding the heat recovery purpose the basic idea of this new hybrid sewer pipe is to use both the ground heat and the wastewater heat with the priority to do the heat transfer with its outside arranged heat pipe system not directly with the wastewater but primarily with the surrounding ground heat with its additionally absorbed waste heat from the sewer pipe. And secondly the sewer pipe can use directly the wastewater heat by heat transfer through the sewer pipe wall. The result is, if a bigger sewer pipe carries more wastewater volume the main waste heat potential will come from the wastewater, but in smaller sewers the more sustainable heat potential will come from the ground heat. Therefore the big advantage of this new sewer pipe is that it can be used for bigger and smaller dimensions, and it is a very low cost installation.

The technology is just in the prototype phase, and Orange Depot & Exchange Systems is searching for partners doing the final developing steps for launching and marketing the product in cooperation worldwide.

TEC MANAGEMENT is an engineering and consulting firm in the field of environmental friendly technologies with focus on underground infrastructures, and beside others specialised on alternative energy storage & supply solutions. Orange Depot & Exchange Systems is the label, under which particular systems, products, and techniques are promoted.

For further information:
Dipl.-Ing. Michael Henze
Orange Depot & Exchange Systems
Mainring 10
63500 Seligenstadt
Phone: +49 (0)6182 / 897967
Fax: +49 (0)6182 / 897968

More News and Articles


TEC Management