HEAT EXCHANGER AND A SYSTEM FOR RECOVERY OF THERMAL ENERGY FROM WASTE WATER

Abstract

The present invention relates to a heat exchanger and a system for recovery of thermal energy from waste water. The heat exchanger comprises: an outer tube, an inner tube for waste water, and a control element, wherein said inner tube is arranged in said outer tube in such a way that a space is formed between said inner tube and said outer tube and wherein said control element is arranged in said space and is arranged to guide a medium in a helical movement around the inner tube so that thermal energy from said waste water is transferred to said medium.

Claims

1. A heat exchanger for recovery of thermal energy from waste water, the heat exchanger comprising: an outer tube; an inner tube for waste water; and a control element wherein said inner tube is arranged inside said outer tube in such a way that a space is formed between said inner tube and said outer tube, and wherein said control element is arranged in said space and is arranged to guide a medium in a helical movement around the inner tube so that thermal energy from the waste water is transferred to said medium.

2. The heat exchanger according to claim 1, wherein said control element is arranged to guide said medium in a space formed between the control element, an outside of the inner tube, and an inside of the outer tube.

3. The heat exchanger according to claim 1, wherein said control element is wound around said inner tube.

4. The heat exchanger according to claim 1, wherein said control element is soldered to the inner tube.

5. The heat exchanger according to claim 1, wherein said inner tube and said outer tube are mounted parallel to the vertical plane.

6. The heat exchanger according to claim 1, wherein said inner tube is arranged centrally in said outer tube.

7. The heat exchanger according to claim 1, wherein the outer tube has an inlet for said medium in a lower portion of said outer tube and an outlet for said medium in an upper portion of said outer tube.

8. The heat exchanger according to claim 1, wherein said inner tube has an inlet for said waste water in an upper portion of said inner tube and an outlet for said waste water in a lower portion of said inner tube.

9. The heat exchanger according to claim 1, wherein the edge of said inlet and/or outlet of said inner tube comprises at least one projection arranged in a direction of flow in said inner tube.

10. The heat exchanger according to claim 1, wherein said inner tube is made of copper.

11. The heat exchanger according to claim 1, wherein said outer tube is made of at least one of: copper, steel, or stainless steel.

12. The heat exchanger according to claim 1, wherein said control element is a tube.

13. The heat exchanger according to claim 1, wherein said medium is water.

14. The heat exchanger according to claim 1, wherein the temperature of said medium when it leaves said outlet for said medium is in the range of 8-50 C.

15. A system for recovery of thermal energy from waste water comprising: a heat exchanger, wherein the heat exchanger comprises: an outer tube, an inner tube for waste water, and a control element, wherein said inner tube is arranged inside said outer tube in such a way that a space is formed between said inner tube and said outer tube, and wherein said control element is arranged in said space and is arranged to guide a medium in a helical movement around the inner tube so that thermal energy from the waste water is transferred to said medium; at least one of a water closet; and a hot water dispenser configured to heat liquid to a predetermined temperature; and at least one of a shower mixer, a kitchen mixer, or a bathroom mixer, wherein said medium is water.

16. The system according to claim 15, comprising a conduit for leading water from said heat exchanger to said hot water dispenser.

17. The system according to claim 15, comprising a conduit for leading water from said heat exchanger to said water closet.

18. The system according to claim 15, comprising a conduit for leading water from said heat exchanger to said shower mixer, wherein said shower mixer is arranged to mix said water with water from said hot water dispenser.

19. A system according to claim 15, comprising a conduit for leading water from said hot water dispenser to said shower mixer, said kitchen mixer or said bathroom mixer, wherein said shower mixer, said kitchen mixer and said bathroom mixer are arranged to mix said water with water from said heat exchanger.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Embodiments of the present invention will hereafter be described in exemplified manner, with reference to the illustrative appended drawings, wherein:

[0044] FIG. 1 shows a cross-section of the heat exchanger according to the invention.

[0045] FIG. 2 shows a schematic view of a system for recovery of thermal energy from waste water according to the invention.

DETAILED DESCRIPTION

[0046] The heat exchanger according to the invention is based on the idea of saving energy by using thermal energy in the waste water to preheat water for use in, for example, bath, shower, dishwashing, clothes washing, and flushing toilets. In order to reach the desired temperature the preheated water sometimes needs to be mixed with water of an even higher temperature. This water with an even higher temperature can be heated by, for example, a hot water dispenser. Water heated by the hot water dispenser can be water preheated by the heat exchanger which, is then further heated by the hot water dispenser.

[0047] FIG. 1 shows a cross-section of the heat exchanger according to the invention. Heat exchanger 100 has an inner tube 110 and an outer tube 120. The inner tube 110 is arranged centrally in the outer tube 120. The inner tube 110 is arranged for leading waste water. Waste water is directed downwards in the figure and flows by means of gravitation.

[0048] A space 130 is formed between the inner tube and the outer tube. A control element 140 extends inside the space 130. The control element is arranged to guide said medium in a helical movement around the inner tube. When a medium is led around the inner tube and waste water flows in the inner tube, thermal energy from the waste water can be transferred to the medium.

[0049] The medium is preferably water. The water can be cold water intended for bath, shower, dish washing, clothes washing, flushing toilets, and watering.

[0050] An inlet 112 for waste water is arranged in an upper portion of the inner tube 110, and an outlet 114 for waste water is arranged in a lower portion of the inner tube 110 for waste water. In an embodiment, such as shown in FIG. 1, the outer tube 120 does not fully encompass the inner tube 110. This is advantageous since it simplifies connecting the heat exchanger 100 with an existing drain tube.

[0051] The edge of inlet 112 and/or of the outlet 114 has a projection 116. The projection 116 protrudes parallel with the center line of the inner tube. The projection 116 simplifies assembling of the heat exchanger 100 since it compensates for any unevenness from sawing the existing drain tube in two. This also creates a slit that facilitates quick distribution of waste water over the internal surface. The slit facilitates quick distribution of waste water over the internal surface. The slit that is created also provides a certain leeway to compensate for assembling of the heat exchanger vertically. The slit is like a slot through which the water may run, and quickly be distributed in and, since the heat exchanger must be assembled vertically, the water will then run over the edge evenly over the tube.

[0052] In one embodiment, the heat exchanger does not comprise a projection. The heat exchanger is instead assembled so that a slit is made when the heat exchanger is assembled vertically.

[0053] When the heat exchanger 100 according to the invention is to be assembled, a portion of an existing drain pipe is sawed off. The inlet 112 and outlet 114 of the inner tube 110 is brought into contact with the edges of the existing drain tube. Since it is difficult to saw the existing drain tube exactly evenly, projection 116 compensates for this so that it is possible to turn the heat exchanger 100 so that it is arranged parallel with the vertical plane and the gravitational field. Two seals (not shown) can then be assembled over the edges of the existing drain tube and the inlet 112 and outlet 114 of inner tube 110. These seals can, for example, be a coarse piece of tubing or rubber that is pressed into place with hose clamps.

[0054] The outer tube 120 has an inlet 122 in its lower portion and an outlet 124 in its upper portion. The inlet 122 leads into a space formed between control element 140, the outside of inner tube 110, and the inside of outer tube 120. Inlet 122 and outlet 124 can, for example, be tubular. Inlet 122 is arranged to lead the medium that is to be heated into the heat exchanger.

[0055] As shown the waste water is intended to be guided parallel with the gravitation and downwards in FIG. 1, see arrows 150 and 151. The medium to be preheated is arranged to be guided upwards in FIG. 1 in a helical movement, see arrows 160 and 165 that show when the medium is guided into and out of the heat exchanger. In this way a counter flow heat exchanger is formed.

[0056] The control element 140, as shown in FIG. 1, can be a tube that is wound around the inner tube 110. The control element is, for example, soldered to the inner tube. The outer tube is then mounted around the inner tube. The outer tube is, for example, pulled outside of the inner tube and the control element. The outer tube can alternately be divided into two parts that are arranged around the inner tube and control element and which is then welded together.

[0057] In one embodiment, the control element is formed as an I-beam in miniature that is wound around the inner tube. This embodiment saves materials and can be made by assembling the outer tube in two halves that are welded together with longitudinal seams in the direction of flow.

[0058] The heat exchanger according to the invention is intended to be assembled in some form of household. It can, for example, be in a multi-family house, an office property, a single-family house, a row house, or a link house. The heat exchanger could also be installed in a boat, house trailer, or recreational vehicle. Since the heat exchanger uses waste water, it needs to be located under the drain inlet in the household. The heat exchanger is thus preferably located under inhabited space, in a cellar or shaft. In multi-family households, for example in apartment houses, one or more heat exchangers according to the invention can be installed.

[0059] The medium that is brought from the heat exchanger according to the invention is sometimes referred to as preheated water here.

[0060] FIG. 2 shows a schematic view of a system according to the invention for recovery of thermal energy from waste water. System 200 comprises the heat exchanger 100 according to the invention. FIG. 2 shows in more detail a suggested fitting for a bathroom. Heat exchanger 100 is connected so that waste water 151 flows into the top of the heat exchanger 100 and flows out at the bottom of heat exchanger 100. Waste water 150 that flows out of heat exchanger 100 is cool in comparison with waste water 151 that flows into heat exchanger 100.

[0061] Cold water 160 is guided into the heat exchanger 100 and is preheated by the heat exchanger 100 by means of heat exchange with the waste water. Preheated cold water 165 is guided further to hot water dispenser 210, to water closet 220, to shower and bath 230, as well as to bathroom mixer 240. The preheated cold water 165 maintains a temperature in the range of approx. 8-50 C. The temperature of the preheated cold water 165 depends on the extent to which it has been heated in the heat exchanger 100. How much the cold water 160 is heated in the heat exchanger 100 depends in turn on how much waste water 151 is led into the heat exchanger 100 and the temperature of waste water 151.

[0062] The preheated cold water 165 in the hot water dispenser 210 is further heated until it reaches a predetermined temperature. The predetermined temperature can, for example, be 55 C. The water warmed to a predetermined temperature is designated here as hot water 170. Hot water 170 is led to shower mixer 230 and bathroom mixer 240. Shower mixer 230 can, for example, be provided in a bathtub or in a shower. Bathroom mixer 240 can, for example, be provided in a sink in the bathroom.

[0063] Shower mixer 230 mixes hot water 170 with the preheated cold water 165 in accordance with what is determined by the user. If, for example, the preheated cold water 165 maintains a temperature in the upper part of the range, then a smaller amount of hot water 170 is added.

[0064] Bathroom mixer 240 mixes hot water 170 with the preheated cold water 165 in accordance with what is determined by the user. If, for example, the preheated cold water 165 maintains a temperature in the upper part of the range, then a smaller amount of hot water 170 is added.

[0065] In one embodiment the bathroom mixer 240 also comprises a connection for cold water. This is advantageous since the user may, for example, want to have drinking water or water for brushing teeth. In one embodiment instead of a connection for cold water, the sink has a separate faucet for cold water.

[0066] If, for example, someone takes a shower, the water flows out in the bathroom drain and is led to the heat exchanger 100. The water in the heat exchanger 100 heats cold water 160 that is led up to the shower mixer 230. The longer time the person showers, the less hot water 170 needs to be added.

[0067] It should be noted that central preparation of hot water can be done, for example, by a remote heat exchanger as an alternative to the hot water dispensers.

[0068] It should be understood that the present invention is not limited to the embodiments described herein. Several modifications and variations are conceivable, for which reason the scope of the invention is exclusively defined by the accompanying claims.