Title:
ENERGY GENERATING ROOF SYSTEM
Kind Code:
A1


Abstract:
An energy generating system comprising a conduit comprising an energy collection portion and a heat exchange portion, wherein the energy collection portion of the conduit is located within an air filled space or a sewer gas exhaust pipe or a ventilation duct, wherein the conduit is adapted to transport a first fluid, wherein the first fluid is adapted to absorb thermal energy when passing through the energy collection portion of the conduit and a first heat exchanger adapted to exchange heat with the first fluid passing through the heat exchange portion of the conduit.



Inventors:
Zaloga, Mykola (Toronto, CA)
Application Number:
12/537507
Publication Date:
02/10/2011
Filing Date:
08/07/2009
Primary Class:
Other Classes:
126/623, 165/104.19
International Classes:
F24J2/46; F24S90/00; F28D15/00
View Patent Images:
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Primary Examiner:
HAILEY III, JOHN C
Attorney, Agent or Firm:
BERESKIN & PARR LLP/S.E.N.C.R.L., s.r.l. (TORONTO, ON, CA)
Claims:
1. An energy generating roof system for a building roof comprising: a plurality of roof support members; a substantially planar vapor barrier located above the roof support members and operatively connected thereto; a plurality of spacing members located above the vapor barrier and secured to the roof support members; a roof covering operatively connected to the spacing members, wherein the roof covering and the vapor barrier define an air filled space therebetween; a conduit comprising an energy collection portion and a heat exchange portion, wherein the energy collection portion of the conduit is located within the air filled space, wherein the conduit is adapted to transport a first fluid, wherein the first fluid is adapted to absorb thermal energy when passing through the energy collection portion of the conduit; and a first heat exchanger adapted to exchange heat with the first fluid passing through the heat exchange portion of the conduit.

2. The system of claim 1 wherein a first pump circulates the first fluid through the conduit.

3. The system of claim 1 further comprising a first thermo-compressor system comprising: a second fluid adapted to circulate through the first heat exchanger and exchange heat with the first fluid a first compressor in fluid communication with the first heat exchanger and adapted to compress the second fluid.

4. The system of claim 3 wherein the first thermo-compressor system further comprises: a second heat exchanger in fluid communication with the first compressor and adapted to exchange heat with the second fluid.

5. The system of claim 4 wherein the first thermo-compressor system further comprises: a first throttle valve in fluid communication with the second heat exchanger and the first heat exchanger and adapted to reduce the pressure of the second fluid.

6. The system of claim 5 wherein the second heat exchanger is adapted to exchange heat between the second fluid and a third fluid.

7. The system of claim 6 wherein the second heat exchanger is located downstream of the first compressor and the first throttle vale is located downstream of the second heat exchanger and upstream of the first heat exchanger.

8. The system of claim 6 wherein the third fluid is adapted to pass through at least one radiator and wherein the at least one radiator is adapted to heat a building.

9. The system of claim 6 further comprising a second thermo-compressor comprising: a third heat exchanger adapted to exchange heat between the third fluid and a fourth fluid; a second compressor in fluid communication with the third heat exchanger and adapted to compress the fourth fluid; a fourth heat exchanger in fluid communication with the second compressor and adapted to exchange heat with the fourth fluid; and a second throttle valve in fluid communication with the fourth heat exchanger and the third heat exchanger and adapted to reduce the pressure of the fourth fluid.

10. The system of claim 9 wherein the fourth heat exchanger is adapted to exchange heat between the fourth fluid and a fifth fluid.

11. The system of claim 1 wherein the energy collection portion of the conduit follows an undulating path comprising a plurality of straight segments and 180 degree elbows.

12. The system of claim 1 wherein the energy collection portion of the conduit defines a tortuous path.

13. The system of claim 11 wherein the plurality of straight segments substantially align with spaces in between the spacing members.

14. A sewer gas heat recovery system comprising; a sewer gas exhaust pipe; a heat recovery conduit comprising an energy collection portion and a heat exchange portion, wherein the energy collection portion of the heat recovery conduit is located within the sewer gas exhaust pipe, wherein the heat recovery conduit is adapted to transport a first heat recovery fluid wherein the first heat recovery fluid is adapted to absorb thermal energy when passing through the energy collection portion of the heat recovery conduit; and a first heat exchanger adapted to exchange heat with the first heat recovery fluid passing through the heat exchange portion of the heat recovery conduit.

15. The system of claim 14 wherein the energy collection portion of the heat recovery conduit comprises a coil.

16. The system of claim 14 further comprising a thermo-compressor comprising: a second fluid adapted to circulate through the first heat exchanger and exchange heat with the first heat recovery fluid; a first compressor in fluid communication with the first heat exchanger and adapted to compress the second fluid; a second heat exchanger in fluid communication with the first compressor and adapted to exchange heat with the second fluid; and a first throttle valve in fluid communication with the second heat exchanger and the first heat exchanger and adapted to reduce the pressure of the second fluid.

17. The system of claim 16 wherein the second heat exchanger is adapted to exchange heat between the second fluid and a third fluid.

18. The system of claim 17 further comprising a second thermo-compressor comprising: a third heat exchanger adapted to exchange heat between the third fluid and a fourth fluid; a second compressor in fluid communication with the third heat exchanger and adapted to compress the fourth fluid; a fourth heat exchanger in fluid communication with the second compressor and adapted to exchange heat with the fourth fluid; and a second throttle valve in fluid communication with the fourth heat exchanger and the third heat exchanger and adapted to reduce the pressure of the fourth fluid.

19. The system of claim 17 wherein the third fluid is adapted to pass through at least one radiator and wherein the at least one radiator is adapted to heat a building.

20. A combined sewer gas heat recovery and energy generating roof system comprising: an energy generating roof system (EGRS) comprising: a plurality of roof support members, a substantially planar vapor barrier located above the roof support members and operatively connected thereto, a plurality of spacing members located above the vapor barrier and secured to the roof support members, a roof covering operatively connected to the spacing members, wherein the roof covering and the vapor barrier define an air filled space therebetween, and a EGRS conduit comprising an energy collection portion, wherein the energy collection portion of the conduit is located within the air filled space, wherein the conduit is adapted to transport a first fluid, wherein the first fluid is adapted to absorb thermal energy when passing through the energy collection portion of the conduit; a sewer gas heat recovery system (SGHRS) comprising: a sewer gas exhaust pipe, and a SGHRS conduit comprising an energy collection portion, wherein the energy collection portion of the SGHRS conduit is located within the sewer gas exhaust pipe, wherein the SGHRS conduit is adapted to transport the first fluid wherein the first fluid is adapted to absorb thermal energy when passing through the energy collection portion of the SGHRS conduit; a first heat exchanger adapted to exchange heat with the first fluid; and a switching valve in fluid communication with the EGRS conduit and the SGHRS conduit, wherein the switching valve is operable between: a first position wherein the first fluid is directed through the energy collection portion of the SGHRS conduit but is prevented from passing through the energy collection portion of the EGRS conduit; a second position wherein the first fluid is directed through the energy collection portion of the SGHRS conduit and through the energy collection portion of the EGRS conduit; and a third position wherein the first fluid is directed through the energy collection portion of the EGRS conduit but is prevented from passing through the energy collection portion of the SGHRS conduit.

21. The combined system of claim 20 further comprising a thermo-compressor comprising: a second fluid adapted to circulate through the first heat exchanger and exchange heat with the first fluid; a first compressor in fluid communication with the first heat exchanger and adapted to compress the second fluid; a second heat exchanger in fluid communication with the first compressor and adapted to exchange heat with the second fluid; and a first throttle valve in fluid communication with the second heat exchanger and the first heat exchanger and adapted to reduce the pressure of the second fluid.

22. The system of claim 21 wherein the second heat exchanger is adapted to exchange heat between the second fluid and a third fluid.

23. The system of claim 22 further comprising a second thermo-compressor comprising: a third heat exchanger adapted to exchange heat between the third fluid and a fourth fluid; a second compressor in fluid communication with the third heat exchanger and adapted to compress the fourth fluid; a fourth heat exchanger in fluid communication with the second compressor and adapted to exchange heat with the fourth fluid; and a second throttle valve in fluid communication with the fourth heat exchanger and the third heat exchanger and adapted to reduce the pressure of the fourth fluid.

24. A ventilation duct heat recovery system comprising; a ventilation duct; a heat recovery conduit comprising an energy collection portion and a heat exchange portion, wherein the energy collection portion of the heat recovery conduit is located within the ventilation duct, wherein the heat recovery conduit is adapted to transport a first heat recovery fluid wherein the first heat recovery fluid is adapted to absorb thermal energy when passing through the energy collection portion of the heat recovery conduit; and a first heat exchanger adapted to exchange heat with the first heat recovery fluid passing through the heat exchange portion of the heat recovery conduit.

Description:

FIELD

The invention relates generally to a system for collecting thermal energy, and more particularly to a system for collecting thermal energy from a building roof and/or from sewer gas.

INTRODUCTION

Energy use, such as electricity or energy from burning fossil fuels, is one of the main expenditures associated with maintaining a building. Reducing the energy required to maintain the building would greatly reduce the cost of maintaining the building and the environmental footprint of a building. Accordingly, it would be desirable to collect energy from other sources which are available without cost.

SUMMARY

The invention provides in one aspect an energy generating roof system for a building roof comprising:

a plurality of roof support members;

a substantially planar vapor barrier located above the roof support members and operatively connected thereto;

a plurality of spacing members located above the vapor barrier and secured to the roof support members;

a roof covering operatively connected to the spacing members, wherein the roof covering and the vapor barrier define an air filled space therebetween;

a conduit comprising an energy collection portion and a heat exchange portion, wherein the energy collection portion of the conduit is located within the air filled space, wherein the conduit is adapted to transport a first fluid, wherein the first fluid is adapted to absorb thermal energy when passing through the energy collection portion of the conduit; and

a first heat exchanger adapted to exchange heat with the first fluid passing through the heat exchange portion of the conduit.

The invention provides in another aspect a sewer gas heat recovery system comprising;

a sewer gas exhaust pipe;

a heat recovery conduit comprising an energy collection portion and a heat exchange portion, wherein the energy collection portion of the heat recovery conduit is located within the sewer gas exhaust pipe, wherein the heat recovery conduit is adapted to transport a first heat recovery fluid wherein the first heat recovery fluid is adapted to absorb thermal energy when passing through the energy collection portion of the heat recovery conduit; and

a first heat exchanger adapted to exchange heat with the first heat recovery fluid passing through the heat exchange portion of the heat recovery conduit.

The invention provides in still another aspect a combined sewer gas heat recovery and energy generating roof system comprising:

an energy generating roof system (EGRS) comprising:

    • a plurality of roof support members,
    • a substantially planar vapor barrier located above the roof support members and operatively connected thereto,
    • a plurality of spacing members located above the vapor barrier and secured to the roof support members,
    • a roof covering operatively connected to the spacing members, wherein the roof covering and the vapor barrier define an air filled space therebetween, and
    • a EGRS conduit comprising an energy collection portion, wherein the energy collection portion of the conduit is located within the air filled space, wherein the conduit is adapted to transport a first fluid, wherein the first fluid is adapted to absorb thermal energy when passing through the energy collection portion of the conduit;

a sewer gas heat recovery system (SGHRS) comprising:

    • a sewer gas exhaust pipe, and
    • a SGHRS conduit comprising an energy collection portion, wherein the energy collection portion of the SGHRS conduit is located within the sewer gas exhaust pipe, wherein the SGHRS conduit is adapted to transport the first fluid wherein the first fluid is adapted to absorb thermal energy when passing through the energy collection portion of the SGHRS conduit;

a first heat exchanger adapted to exchange heat with the first fluid; and

a switching valve in fluid communication with the EGRS conduit and the SGHRS conduit, wherein the switching valve is operable between:

    • a first position wherein the first fluid is directed through the energy collection portion of the SGHRS conduit but is prevented from passing through the energy collection portion of the EGRS conduit;
    • a second position wherein the first fluid is directed through the energy collection portion of the SGHRS conduit and through the energy collection portion of the EGRS conduit; and
    • a third position wherein the first fluid is directed through the energy collection portion of the EGRS conduit but is prevented from passing through the energy collection portion of the SGHRS conduit.

DRAWINGS

For a better understanding of the embodiments described herein and to show more clearly how they may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings which show at least one exemplary embodiment, and in which:

FIG. 1 is a cross-sectional front view of a roof structure according to an embodiment of an energy generating roof system;

FIG. 2 is a cross-sectional side view of a roof structure according to an embodiment of the energy generating roof system for collecting thermal energy from a roof;

FIG. 3 is a partial schematic view of an embodiment of an energy generating roof system for collecting thermal energy from a roof;

FIG. 4. is a partial schematic view of an energy collection portion of a conduit within two exemplary roofs;

FIG. 5. is a schematic view of area A of FIG. 4;

FIG. 6. is a partial schematic view of another embodiment of the energy generating roof system for collecting thermal energy from a roof;

FIG. 7. is a partial schematic view of an embodiment of an energy collection system for collecting energy from sewer gas;

FIG. 8. is a partial schematic view of yet another embodiment of the energy generating roof system; and

FIG. 9 is a schematic view of a building illustrating the location of the heat recovery conduit of the embodiment of FIG. 7.

DESCRIPTION OF VARIOUS EMBODIMENTS

Referring to FIGS. 1 and 2, an exemplary roof 9 of energy generating roof system (EGRS) 10 is shown. Roof 9 may be of any type including, without limitation, a flat roof, a gable roof, a cross gable roof, a mansard roof, a hipped roof, a cross-hipped roof, a pyramidal roof, a shed roof, a saltbox roof and a gambrel roof. Roof 9 includes one or more roof support members 1, vapor barrier 2, spacing members 6 and a roof covering 5.

Vapor barrier 2 is located above and operatively connected to the one or more roof support members 1. The vapor barrier may be a plastic film or any other suitable material. In some embodiments, a roof support member 1 may be a joist, beam or rafter. An intermediate layer 3, such as plywood sheets, metal sheets, or lumber, may be located above and secured to roof support members 1 in any suitable manner, such as by fasteners. The vapor barrier 2 may cover the intermediate layer 3.

Spacing members 6 are located above the vapor barrier 2 and are preferably secured to the roof support members 1 in any suitable fashion, such as by fasteners. Preferably, spacing members 6 are spaced apart and are parallel to each other. In some embodiments, cross members 4 are located above spacing members 6 and secured to the spacing members 6 via fasteners. Cross members 4 may be parallel to each other and oriented at an angle (such as a 90 degree angle) to the spacing members 6. In some embodiments, spacing members 6 may be strapping. In yet other embodiments the, cross members 4 may be part of the spacing member structure.

The roof covering 5 is located above and is secured to preferably spacing members 6. Roof covering 5 may be of any type including, without limitation, steel, shingle, clay, cedar, and concrete. The roof covering 5 and the vapor barrier 2 define an air filled space 8 therebetween. Located within the air filled space 8 may be spacing members 6 and other roof elements.

Referring now to FIG. 3, a schematic of the first embodiment of EGRS 10 is shown. EGRS 10 includes a conduit 11 which transports a first fluid 17. Conduit 11 may be of any suitable type and cross-section. In some embodiments, conduit 11 may be a pipe or a hose. Conduit 11 includes an energy collection portion 12 and a heat exchange portion 13. Preferably, the energy collection portion 12 of conduit 11 is arranged in a tortuous or undulating path within the air filled space 8. In some embodiments, energy collection portion 12 includes a plurality of straight segments and 180 degree elbows (shown in FIGS. 4 and 5). Further, the straight segments may substantially align with the spaces in between the spacing members 6 (shown in FIGS. 4 and 5). A pump 14 circulates the first fluid 17 within the conduit 11. It will be appreciated that factors, such as solar radiation and heat rising from the interior of the building may cause the air temperature within the air filled space 8 to rise relative to the ambient temperature. The thermal energy in the air filled space 8 heats the first fluid 17 as it passes through the energy collection portion 12 of conduit 11.

The pump 14 circulates the heated first fluid through the heat exchange portion 13 of conduit 11 which is located in a first heat exchanger 16 of a first thermocompressor 15. The first heat exchanger 16 may be a vessel in which the heat exchange portion 13 of conduit 11 is located. Preferably, the heat exchange portion 13 is a coil (not shown) within the vessel. A second fluid 18 passes through the vessel outside the coil. First heat exchanger 16 exchanges heat between the first fluid 17 and the second fluid 18 which circulates through first thermocompressor 15. First thermocompressor 15 comprises first heat exchanger 16, first compressor 19, second heat exchanger 20, first throttle valve 21, the second fluid 18, and a line 50 through which the second fluid 18 flows between the above components. First and second fluids 17, 18 may be any fluids suitable for retaining and transmitting heat. In some embodiments, the first fluid 17 may be water or a water antifreeze mixture, and the second fluid 18 is preferably a refrigerant. In exemplary embodiments, as shall be described below, second fluid 18 may be present in one or both of gaseous and liquid states at various points as it circulates within thermocompressor 15. Specifically, the exchange of heat from first fluid 17 to second fluid 18 at first heat exchanger 16 may cause second fluid 18 to evaporate. Evaporated second fluid 18 is compressed by first compressor 19 to raise the pressure of the second fluid 18 as it passes through the first compressor 19. This also has the effect of heating second fluid 18 to an elevated temperature. The gaseous second fluid 18 then flows through second heat exchanger 20 which facilitates the exchange of heat between the gaseous second fluid 18 and a third fluid 22 circulating through second conduit 24. Preferably, the second heat exchanger is identical to the first heat exchanger 16. The loss of heat from second fluid 18 to third fluid 22 causes gaseous second fluid 18 to cool and condense into a liquid. The throttle valve 21 permits the second fluid to expand, reducing the pressure of the second fluid 18. The reduction in pressure permits second fluid 18 to evaporate at lower temperatures within first heat exchanger 16.

In some embodiments, third fluid 22 circulating in second conduit 24, heated from circulating through second heat exchanger 20 is adapted to pass through at least one radiator 23 connected to second conduit 24. The radiator 23 heats a building or room where it is located. In other embodiments, third fluid 22 may pass into the hot water pipe system of a building. Any embodiments described herein where fluid is said to pass through at least one radiator 23, will be understood to include alternative embodiments where that fluid is instead the hot water source for a building.

First and second heat exchangers 16, 20 may be any heat exchanger suitable for transferring heat between fluids. These may include, without limitation, shell and tube heat exchangers, plate heat exchangers, regenerative heat exchangers, spiral heat exchangers, cross-flow heat exchangers, parallel flow heat exchangers and phase-change heat exchangers. The selection of heat exchangers 16, 20 may be based at least in part on the selected elemental states (e.g. gaseous or liquid) of the fluids passing through each respective heat exchanger. As explained above, while the particular implementation described herein includes a second fluid 18 which passes between liquid and gaseous states, other embodiments may utilize a second fluid which remains in a single state (e.g. either gaseous or liquid).

In operation, a first fluid 17 is circulated by pump 14 from the outlet of first heat exchanger 16 to the energy collection portion 12 of conduit 11 inside the air filled space 8 of the roof 9. The relatively hotter air in the air filled space 8 heats the first fluid 17 in the energy collection portion 12 of conduit 11. The temperature of the air filled space 8 and the amount of warming the first fluid 17 undergoes depends on the season and the climate in which the building is located. First fluid 17 then passes through heat exchange portion 13 of conduit 11 located in the first heat exchanger 16. First fluid 17, entering the first heat exchanger 16 at an elevated temperature, exchanges heat with second fluid 18 which enters the first heat exchanger 16 at a lower temperature. The transfer of heat energy into second fluid 18 causes second fluid 18 to evaporate. Gaseous second fluid 18 has a temperature on the order of +6° C. when it enters first compressor 19 which raises the pressure and temperature of second fluid 18 to a temperature in the range of about +35° C. to +65° C. The gaseous second fluid 18 is then condensed into a liquid as it passes through second heat exchanger 20 and transfers heat to third fluid 22. Before re-entering first heat exchanger 16, the pressure of liquid second fluid 18 is reduced at a first throttle valve 21. Third fluid 22, circulating through second conduit 24, exits second heat exchanger 20 after receiving heat from second fluid 18 at a temperature of about 65° C. before passing through one or more radiators 23 which are adapted to heat a building.

Further reference is now made to FIG. 6 in which a second exemplary embodiment is shown that may be particularly suitable when the outside temperature is especially low. In this embodiment, a second thermocompressor 32 is situated intermediate the first thermocompressor 15 and the one or more radiators 23. The components of the first thermocompressor 15 are identical to those described in the first embodiment, and will not be further described. Second thermocompressor 32 includes a third heat exchanger 25, second compressor 27, fourth heat exchanger 28, second throttle valve 29 and fourth fluid 26, all of which are connected by second line 60. Instead of the third fluid 22 flowing through one or more radiators 23, it flows through the third heat exchanger 25 of second thermocompressor 32.

Third heat exchanger 25 exchanges heat between third fluid 22 and fourth fluid 26 which circulates through second thermocompressor 32. Third and fourth fluids 22, 26 may be any fluids known in the art suitable for retaining and transmitting heat. In some embodiments, third and fourth fluids 22, 26 may be a refrigerant. In exemplary embodiments, as shall be described below, fourth fluid 26 may be present in one or both of gaseous and liquid forms at various points within second thermocompressor 32 as it circulates therethrough. Specifically, the exchange of heat from third fluid 22 to fourth fluid 26 at third heat exchanger 25 may cause fourth fluid 26 to evaporate. Evaporated fourth fluid 26 is compressed by second compressor 27, heating fourth fluid 26 to an elevated temperature and pressure. The gaseous fourth fluid 26 flows through fourth heat exchanger 28 which exchanges heat between gaseous fourth fluid 26 and fifth fluid 31 circulating through third conduit 30. The loss of heat from fourth fluid 26 to fifth fluid 31 causes gaseous fourth fluid 26 to cool and condense into a liquid. As it passes through second throttle valve 29, the fourth fluid 26 expands (i.e. has its pressure reduced).

In operation, ambient outside air temperature may be as low as −30° C. or lower. In a manner similar to as described with respect to the first embodiment, very cold first fluid 17 circulates into the energy collection portion 12 of conduit 11 and is heated therein. The first fluid 17, now with an elevated temperature, passes through the first heat exchanger 16, exchanging heat with second fluid 18. Second fluid 18 evaporates from the receipt of heat from first fluid 17 and enters first compressor 19 with a temperature on the order of −26° C. The first compressor 19 compresses the second fluid 18 to an elevated temperature and pressure. Second fluid 18 enters second heat exchanger 20 with a temperature in the range of about +0° C. to +15° C. and transfers heat to third fluid 22 circulating in second conduit 24. Third fluid 22 passes through third heat exchanger 25 and exchanges heat with fourth fluid 26. Fourth fluid 26 evaporates on receipt of heat from third fluid 22 and enters second compressor 27 with a temperature of about +6° C. The second compressor 27 compresses the fourth fluid 26 to an elevated temperature and pressure. Fourth fluid 26 enters fourth heat exchanger 28 with a temperature in the range of about +35° C. to +65° C. and transfers heat to fifth fluid 31 circulating in third conduit 30. The fifth fluid 31 exits fourth heat exchanger 28 with a temperature on the order of +60° C. before circulating through the one or more radiators 23.

Further reference is made to FIG. 7 in which an embodiment of a sewer gas heat recovery system (SGHRS) 34 is shown. A second valuable source of heat may be recovered from a sewer gas exhaust, which is typically filled with exhaust gases having a temperature of about 20° C. The temperature of the sewer gas exhaust remains relatively constant year round. SGHRS 34 may be installed in a new or existing sewer gas exhaust pipe. The SGHRS 34 includes a heat recovery conduit 36 having a heat collection portion 37 which is located in a sewer gas exhaust pipe 35. FIG. 9 shows a preferred location of the heat collection portion 37 of the heat recovery conduit 36 within a sewer gas exhaust pipe installed in a typical residential building. As shown in FIG. 9, the heat collection portion 37 is preferably located in a section of the sewer gas exhaust pipe 35 located above the uppermost sewage inflow pipe 35a and below the roof. This location is beneficial because it maintains the heat collection portion 37 of the heat recovery conduit 36 free of fecal matter and is typically the portion of the sewer gas exhaust pipe 35 having the highest temperature. This in turn improves the energy balance of the system. In alternative embodiments where the building has more than one sewer gas exhaust pipe, the heat recovery conduit 36 may have multiple heat collection portions 37 located in some or all of the sewer gas exhaust pipes. While FIG. 9 shows the building sewage pipes connected to a sanitary sewage system, the SGHRS will also work in the same manner if the building sewage pipes are connected to a septic tank.

Referring again to FIG. 7, heat recovery conduit 36 also includes a heat exchange portion 38. In some embodiments, heat collection portion 37 may have a shape which maximizes the surface area of heat collection portion 37 exposed to the gases flowing through the sewer gas exhaust pipe 35. Accordingly, in some embodiments, heat collection portion 37 may comprise a coil or may define a tortuous path. It will be understood that the heat collection portion 37 may have any other suitable shape. The heat recovery conduit 36 may be of any suitable type, such as a pipe or a hose or a combination thereof.

A first heat recovery fluid 39 flows through the heat recovery conduit 36. First heat recovery fluid 39 absorbs thermal energy when passing through the energy collection portion 37 of heat recovery conduit 36. The heat exchange portion 38 circulates first heat recovery fluid 39 through first heat exchanger 16 of first thermocompressor 15. The operation of first thermocompressor 15 is the same as was described with reference to the EGRS 10. SGHRS 34 may include either a single thermocompressor 15, as described above with reference to the first embodiment of the EGRS 10, or first and second thermocompressors 15, 32 as described above with reference to the second embodiment of the EGRS 10. Consequently, the operation of thermocompressors 15, 32 will not be further described.

Although the embodiment described in FIGS. 7 and 9 recovers heat from a sewer gas exhaust pipe, in other embodiments, the same system can recover heat from a ventilation duct of a building. Specifically, the heat collection portion 37 of the heat recovery conduit 36 may be located inside a building ventilation duct. In all other respects, this embodiment will operate identically to the embodiment of FIGS. 7 and 9.

Preferably, the SGHRS 34 and the EGRS 10 are each a system in which heated fluid is supplied to heat fluid inside thermocompressors, with the difference being the source of heat for the heated fluid. The SGHRS 34 recovers heat from sewer exhaust gases and the EGRS 10 collects heat from a warmed air filled space beneath a roof covering.

In some embodiments, the two systems 10, 34 may be combined, as will now be described with further reference to FIG. 8. The combined system 45 comprises the elements of both the SGHRS 34 and the EGRS 10 where a common heat transfer portion 70 is connected to a SGHRS conduit 72 and a EGRS conduit 74. The SGHRS conduit 72 and EGRS conduit 74, include energy collection portions 37 and 12, respectively. The energy collection portions 37 and 12 are identical to those previously described. A first fluid 44 travels through the conduit formed by SGHRS conduit 72, EGRS conduit 74 and the heat transfer portion 70, as described in more detail below. The first fluid 44 circulates through first heat exchanger 16 of first thermocompressor 15. The operation of first thermocompressor 15 in this embodiment is the same as previously described. Combined system 45 may include either a single thermocompressor 15 or first and second thermocompressors 15, 32 as previously described.

The SGHRS conduit 72 and EGRS conduit 74 intersect at switching valve 40. Preferably, the switching valve is a rotating 90 degree elbow valve located at the intersection of four pipes. The rotating elbow may be controlled in any suitable fashion. Switching valve 40 may operate in one of at least three positions as described in more detail below.

In first switch position 41, switching valve 40 permits fluid from the SGHRS conduit 72 to circulate through the first heat exchanger 16, but prevents fluid from the EGRS conduit 74 from passing through the first heat exchanger 16. In some embodiments, this may permit EGRS 10 to receive maintenance or in cases of low outdoor temperatures this may permit combined system 45 to operate at greater efficiency.

In a second switch position 42, switching valve 40 directs first fluid 44 to pass through both the SGHRS conduit 72 and EGRS conduit 74 before entering first heat exchanger 16. Further, flow exiting first heat exchanger 16 does not directly re-enter energy collection portion 12, but instead flows through heat collection portion 37 of SGHRS 34. Preferably, second switch position 42 directs the flow of the first fluid 44 to circulate through the heat collection portion 37 of the SGHRS conduit 72, then through the energy collection portion 12 of EGRS conduit 74 before exchanging heat with the first heat exchanger 16. In some embodiments, this may permit combined system 45 to operate at greater efficiency.

In third switch position 43, switching valve 40 permits fluid from the EGRS conduit 74 to circulate through the first heat exchanger 16, but prevents fluid from the SGHRS conduit 72 from passing through the first heat exchanger 16. In some embodiments, this may permit SGHRS 34 to receive maintenance.

It will be understood that the circulation of the various fluids of the systems described herein may be effected by any number of suitable pumps or other fluid motive means. Further, the operation of such pumps and any other electrical equipment, such as switching valve 40 (if it is electrically controlled) may be effected by any suitable circuitry, sensors or other equipment. For instance, where a system described herein is used to circulate hot fluid through radiators to heat a building, the speed of the various pumps, which circulate the fluids of the system, may be regulated according to thermostats in order to achieve and maintain a set-point temperature. Further, improved efficiency may be achieved in any of the systems described herein by powering any required electrical equipment with electricity produced by renewable sources such as solar and wind powered generators.

The embodiments of the present invention provide numerous advantages over the prior art. Specifically, they are an improvement over geothermal systems because they eliminate the need to dig trenches or bore holes, which can add significant cost. In addition, the above embodiments can be retrofitted into existing buildings, and the installation does not depend on weather conditions or the geology of building location (i.e. whether the location is rocky or other adverse geological conditions). The embodiments of the present invention facilitate reduction in use of fossil fuels and electricity, thereby benefiting the environment.

While certain features of the invention has been illustrated and described herein, many modifications, substitutions, changes, and equivalents will now occur to those of ordinary skill in the art. It is, therefore, to be understood that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.