WO2009058111A1

WO2009058111A1 - Fuel cell for hvac&r

Info

Publication number: WO2009058111A1
Application number: PCT/US2007/022817
Authority: WO
Inventors: Alexander Lifson; Michael F. Taras
Original assignee: Carrier Corporation
Priority date: 2007-10-29
Filing date: 2007-10-29
Publication date: 2009-05-07

Abstract

A heating, ventilation, air conditioning and refrigeration systems receiving electric power from the grid include a control for monitoring the ongoing price of electric power and, when this price exceeds a threshold value, a fuel cell is engaged to temporarily provide electric power to the system. When the price of electric power provided by the grid drops below the threshold, the use of the electric grid is resumed and the fuel cell may be turned off. Provision is also made to operate both the electric grid and the fuel cell in parallel, and for selectively providing electric power from the fuel cell and the electric grid.

Description

FUEL CELL FOR HVAC&R

Technical Field

[0001] This invention relates generally to heating, ventilation, air conditioning and refrigeration (HVAC&R) systems and, more particularly, to selective use of a fuel cell in combination therewith.

Background of the Invention

[0002] The cost of electricity from an electric grid fluctuates substantially over a sufficiently long period of time such as a day, a month or a year. In particular, the price of electricity varies during a period of one day, especially as compared between peak and off-peak hours. That is, during the daytime, and particularly during extreme temperature conditions, the electricity demand is high and the price of electricity rises accordingly. During nighttime hours, however, the demand is normally low and the price of electricity is substantially reduced. The need to pay premium prices for electricity during peak hours therefore causes substantial net price increases for overall power usage by the HVAC&R equipment. [0003] As environmental concerns mount, the use of fuel cells as a power supply is expanding. Currently, fuel cells are in the development stages and making inroads into the automotive sector and residential applications. In the majority of residential applications, the fuel cells have been considered as a backup source of electricity for critical installations such as hospitals, day care facilities, government offices, control centers and the like. In this capacity, the fuel cells are generally not used except during the periods of time when the normal power is down, or not providing sufficient capacity to meet the needs of the user.

Disclosure of the Invention

[0004] A power usage site is provided with a fuel cell for augmenting the delivery of power on a selective basis. The on-going price of electric power is monitored, and during periods in which the price exceeds a predetermined or calculated threshold, the fuel cell is engaged for providing the entire or partial power needs of the user. In this way, power supply from the grid during high peak, high cost usage is eliminated or reduced.

[0005] On the other hand, during off-peak hours, a fuel cell may return an excess of provided power to an electric grid. Feasibility analysis of such mode of operation may be based on a predetermined or calculated threshold. Further, the price of electricity may be predicted ahead of time based on available information. [0006] In the drawings as hereinafter described, preferred and modified embodiments are depicted; however, various other modifications and alternate constructions can be made thereto without departing from the spirit and scope of the disclosure.

Brief Description of the Drawings

[0007] FIG. 1 is a schematic illustration of use of a fuel cell in combination with an HVAC&R system in accordance with the present invention.

[0008] FIG. 2 is an alternative embodiment thereof.

[0009] FIG. 3 is a graphic illustration of fuel cell use in respect to electricity price.

Detailed Description of the Invention

[0010] As shown in Fig. 1, a heating, ventilation, air conditioning and refrigeration (HVAC&R) system 11 is electrically connected to an electric utility or grid 12 by way of an electric line 13. An electric switch 14 is provided such that,, a fuel cell 16 may be electrically connected to the HVAC&R system 11 by way an electric line 17. The electric switch 14 is operated by a control 18. The control 18 may be a control for the HVAC&R system 11 or a stand-alone control. [0011] Recognizing that the cost of electricity from the electric grid 12 may vary substantially from day-to-day and hour-to-hour within a day, a monitor 19 is provided for the purpose of continually or periodically monitoring the price of electricity from the electric grid 12. The cost of components to power the fuel cell can also be continuously or periodically monitored. For example, the cost of the fuel on the anode side of the fuel cell and the cost of the oxidant on the cathode side of the fuel cell can be monitored. . The determination of the electricity cost, and the cost to run the fuel cell, if required, may be accomplished via receiving such information through a connection to the Internet or other information carrying media. Alternatively, the price of electricity may be predicted ahead of time based on available to date information. In response to this cost or price information being received by the control 18, the electric switch 14 is controlled in such a manner that, during periods in which the price of electricity from the electric grid 12 is at higher rates, the fuel cell would be activated through an electric line 21. The comparison of cost of powering the fuel cell to run the HVAC&R system versus the cost of electricity from the electric grid 12 is compared, and the best source of power, either the electric grid 12 or the fuel cell 16, is chosen or re-selected, typically when the cost difference exceeds the predetermined or calculated threshold. To alternate between the grid and the fuel cell, the electric switch 14 is moved to the open position to disconnect the electric grid 12 and to the closed position to connect the fuel cell 16 such that all of the electric power is delivered by the fuel cell 16, during the periods of time when the cost of electricity from the electric grid 12 is high. On the other hand, when the price of electricity has been determined to again be at a lower rate, the electric switch 14 will be moved back to the closed position to connect the electric grid 12 and to the open position to disconnect the fuel cell 16 such that all of the electric power is delivered by the electric grid 12, and the fuel cell 16 will be disengaged or turned off.

[0012] As is seen in Fig. 2, the graph illustrates the trend in which the price of electricity rises and falls in a typical period of one day, as shown by the price trend line A. As the price of electricity rises above a threshold price, as indicated by the region to the right of the intersection point M for the electricity price trend line A the dashed threshold line B, the fuel cell 16 may be switched on and remain engaged as long as the price of electricity exceeds the threshold price level B by a certain amount. At the point N, the price of electricity represented by the electricity price trend line A has been found to have lowered to the threshold level B, at which time, the fuel cell may be turned off or disengaged, and the electric grid is switched on to provide power to the HVAC&R system, as indicated by the region to the right of the intersection point N for the electricity price trend line A the dashed threshold line B. It has to be understood that the threshold line B does not have to be associated with the same threshold value or does not have to be a horizontal line at all. For instance, if the dashed threshold line B represents a trend line for the cost (or price) of the materials required to operate the fuel cell, it may fluctuate during the course of the day, a week or a month. Further, the switch between the electric grid power supply and the fuel cell power supply doesn't have to occur precisely at the intersection points M and N. Since small fluctuation in prices may cause frequent alteration between the two devices leading to wear of the system components and reduced reliability, the "dead" zones, surrounding the intersection points M and N and not allowing for these frequent switchovers, may need to be established. [0013] Referring now to Fig. 3, similar system is shown with a pair of electric switches 22 and 23 being connected to the control 18 by the respective electric lines 24 and 26. It should be understood that the function of the electric switch 22 and switch 23 can be combined into one multifunctional switch. With this arrangement, the control 18 can operate in the same manner as described hereinabove by closing one of the switches 22 or 23 while opening the other. However, it is also possible to simultaneously close both switches 22 and 23 such that the electric grid 12 and fuel cell 16 may operate in parallel in providing electric power to the HVAC&R system. Further, such an arrangement allows the fuel cell 16 to deliver power back to the electric grid 12, for instance, during the periods of time in which the price of electricity is high and the electricity supply is at a premium, and the utility is then able and wants to "buy back" electricity being delivered by the fuel cell 16.

[0014] It should be understood, that additional factors may come into play when choosing the most appropriate mode of operation in regards to utilization of the fuel cell versus using electricity from the grid. For example, as slated above, under some circumstances, it might be undesirable to have a rapid switching from fuel cell to the electric grid and back. Therefore, a threshold value of the difference between the cost of operating the fuel in comparison to the cost of the electricity provided by the grid may be established. In this case, the switchover between these two electric power supply devices will be made only when such a threshold is exceeded and the rapid switching is avoided. Other factors may also come into consideration in determining the most effective mode of operation. As an example, it might be advantageous to bias the operation of the HVAC&R system toward the electric grid power supply if it is determined that prolonged operation using the fuel cell may affect its reliability. In other words, if prolonged operation of the fuel cell results in undesirable wear and tear of the fuel cell, then the HVAC&R may be connected to the electric grid (and disconnected from the fuel cell), even under conditions when the price of electricity would dictate otherwise. It should also be understood that the schematic representations of the invention exhibited in Figures 1 and 3 are very much simplified, and are shown for illustration purpose only. Someone knowledgeable in the art should be able to extend these basic schematics to more elaborate control systems. Figures 1 and 3 show the monitor connection only to determine the price of the electricity, however other information (not shown) can be gathered by the monitor to determine the cost of other commodities involved, such as, for example, the cost of fuel and oxidant to run the fuel cell, as well as other operational or environmental parameters affecting the system as a whole. [0015] It should be recognized that, the present invention is applicable to all types of HVAC&R systems such as commercial and residential air conditioning and heat pump systems as well as refrigeration systems such as those utilized in supermarkets and mobile applications. Further, various refrigerant types could be used within the refrigerant systems. These refrigerants types may include, but are not limited to conventional HFC refrigerants such as for instance R410A, R404A and Rl 34a or natural refrigerants such as for example R744, R717 and R290. [0016] While the present invention has been particularly shown and described with reference to a preferred and modified embodiment as illustrated in the drawings, it will be understood by one skilled in the art that various changes in detail may be affected therein without departing from the spirit and scope of the invention as defined by the claims.

Claims

We Claim:

1. Apparatus for selective control of power usage from an electric grid which provides an electric power supply to an HVAC&R system at variable prices dependent on demand and other factors, comprising: a fuel cell capable of generating electric power sufficient to at least partially meet the needs of the HVAC&R system; a monitor for monitoring at least the price of electric power being provided by the electric grid; a control for receiving the output from said monitor and responsively connecting the fuel cell to the HVAC&R system, to provide at least partial power supply to the HVAC&R system, based on at least the price of the electric power.

2. Apparatus as set forth in claim 1, wherein the cost of operating the fuel cell is also taken into account when said fuel cell is responsively connected to said HVAC&R system.

3 Apparatus as set forth in claim 2, wherein said cost of operating said fuel cell includes at least the cost of fuel and the cost of oxidant.

4. Apparatus as set forth in claim 2, wherein said cost of operating said fuel cell includes wear and tear of the fuel cell.

5. Apparatus as set forth in claim 1 and including at least one electric switch that is operable by said control to responsively connect said fuel cell to said HVAC&R system.

6. Apparatus as set forth in claim 5 wherein said at least one electric switch is responsive to said control to disconnect said electric grid from said HVAC&R system.

7. Apparatus as set forth in claim 5 wherein said at least one electric switch is also being connectable between said electric grid and said HVAC&R system.

8. Apparatus as set forth in claim 5 wherein at least one electric switch is also operable to facilitate the flow of electric energy between said fuel cell and said electric grid.

9. Apparatus as set forth in claim 1, wherein the price of electric power provided by said electric grid is periodically monitored by said monitor.

10. Apparatus as set forth in claim 1, wherein the price of electric power provided by said electric grid is continuously monitored by said monitor.

11. Apparatus as set forth in claim 1 , wherein the price of electric power provided by said electric grid is predicted ahead of time.

12. Apparatus as set forth in claim 1, wherein the price of electric power provided by said electric grid is received by said monitor via Internet.

13. A method of controlling the usage of electric power from an electric grid which provides electric power at variable prices depending on demand and other factors, comprising the steps of: providing a fuel cell capable of generating electric power sufficient to at least partially meet the needs of an HVAC&R system; monitoring at least the on going price of electric power being provided by the electric grid and establishing appropriate connection of said fuel cell to said HVAC&R system based on at least the monitored price.

14. A method as set forth in claim 13, wherein, in addition to the price of electricity, the cost of operating the fuel cell is taken into account for establishing appropriate connection between said fuel cell and said HVAC&R system.

15. A method as set forth in claim 14, wherein said cost of operating said fuel cell includes at least the cost of fuel and the cost of oxidant.

16. A method as set forth in claim 14, wherein said cost of operating said fuel cell includes wear and tear of the fuel cell.

17. A method as set forth in claim 13, wherein the connecting step is accomplished by at least one electric switch that is operable by said control to responsibly connect said fuel cell to said HVAC&R system.

18. A method as set forth in claim 17, wherein said at least one electric switch is responsive to said control to disconnect said grid from said HVAC&R system.

19. A method as set forth in claim 17, wherein said at least one electric switch is also being connectable between said electric grid and said HVAC&R system.

20. A method as set forth in claim 17 and including the step of operating said at least one electric switch such that the flow of electric energy between said fuel cell and said electric grid is facilitated.

21. A method as set forth in claim 13, wherein the price of electric power provided by said electric grid is periodically monitored.

22. A method as set forth in claim 13, wherein the price of electric power provided by said electric grid is continuously monitored.

23. A method as set forth in claim 13, wherein the price of electric power provided by said electric grid is predicated ahead of time.

24. A method as set forth in claim 13, wherein the price of electric power provided by said electric grid is received via Internet.