CA2745590A1 - Hybrid horizontal drainpipe heat exchanger - Google Patents

Abstract

The present invention is low-cost hybrid horizontal drainpipe heat exchanger that has a large internal diameter and that is best suited for long length application. Several embodiments are disclosed for drainwater heat recovery including a first to ambient air, a second to water with a single-wall-of-separation to the water, and a third having a double-wall-of-separation along with a vent to the ambient. All are based on a hybrid tube wherein a relatively narrow concave copper strip (a tube segment) is engaged in matching curved recesses in a large bore plastic tube segment. In the drainwater-to- fresh water embodiments a pressure chamber for the water supply is created beneath the concave copper strip by means of a thick, elongated gasket that seals against it and against the inner wall of a second plastic tube segment. Inlet and outlet fittings connect between a building's cold water supply and a hot water heater or a faucet. Socket fittings on each end of the hybrid tube heat exchanger provide connection means to standard drainpipe. Because of the low cost and where the length cannot be long, multiple units can be run in parallel or in series or in a zig-zag arrangement.

Claims (7)

1. A hybrid tube heat exchanger comprising:

a first heat transfer element comprising a tube segment of thermally conductive material and having inner and outer surfaces and longitudinal edges with marginal areas;

an enclosing element comprising a tube segment having inner and outer walls and a longitudinal gap oriented downwards and having recesses in said inner wall adjacent said longitudinal gap;

said marginal areas of said first heat transfer element sealingly engaged in said recesses thereby creating a fluid conduit;

the arrangement being that a first fluid flowing on said inner surface may transfer heat to a second fluid adjacent said outer surface.

2. The hybrid tube of Claims 1 and 2 where said enclosing element comprises second and third tube segments each with longitudinal gaps of different widths and concentrically arranged to define said recesses.

3. The hybrid tube of Claim 1 further including external clamping means.

4. The heat exchanger of Claims 1, 2 and 3 where said gap in said tube segment is a tight fit between said recesses.

5. A heat exchanger comprising.

the hybrid tube of Claim s 1 and 2 where, said hybrid tube has a central heat transfer portion and end portions;

said outer surface of said first heat transfer element having a peripheral margin area within said heat transfer portion;

a peripheral gasket contacting said peripheral margin area;

a forth tube segment enclosing said central heat transfer portion and generally concentric therewith and having inner and outer walls;

said gasket contacting said inner wall thereby defining a chamber;
said forth tube segment having inlet and outlet means to said chamber;
clamping means exterior to said outer walls;

the arrangement being that a first fluid flowing through said hybrid tube can transfer heat with a second fluid flowing through said chamber.

6. The heat exchanger of Claim 5 further including fifth spacer tube segment between said forth tube segment and said third tube segment of said enclosing element.

7. A heat exchanger comprising the hybrid tube of Claim 5 further including, a second heat transfer element having inner and outer surfaces;

said second heat transfer element located within said heat transfer portion;

said second heat transfer element located within said longitudinal gap such that at least one longitudinal vent is created therebetween;

said inner surface in thermal contact with said outer surface of said first heat transfer element;

said outer surface in contact with said peripheral gasket;

the arrangement being that heat transferred between said first and second fluids passes through both said heat transfer elements.