GB2155111A

GB2155111A - Power generator apparatus

Info

Publication number: GB2155111A
Application number: GB08503442A
Authority: GB
Inventors: Masayasu Taguchi; Kazuo Seino
Original assignee: Hitachi Zosen Corp
Current assignee: Hitachi Zosen Corp
Priority date: 1984-02-10
Filing date: 1985-02-11
Publication date: 1985-09-18
Also published as: GB2155111B; GB8503442D0; JPS60166764A

Abstract

Power generator apparatus includes a first power generating means in which a condensing means condenses rays of sunlight on thermoelectric elements (17) which convert solar thermal energy into electric energy, and a second power generating means (29) in which a power generator is driven to produce electric power by repeated deformation and restoration of a power source made of a shape memory alloy, such repeated deformation and restoration of the power source caused by the difference in temperature between cooling water 20, 24 and warm waste water 25 discharged as heated by the thermoelectric elements when they are cooled. <IMAGE>

Description

SPECIFICATION Power generator apparatus The present invention relates to power generator apparatus for converting solar thermal energy into electric energy.

In order to utilize solar thermal energy efficiently, power generator apparatus has been proposed in which condenser means such as a Fresnal lens, a normal convex lens or a paraboloid reflex mirror, condenses rays of sunlight on thermal medium pipes disposed at or adjacent the focus of such condensor means, thereby to heat to high temperatures a thermal medium such as water, oil or the like flowing in the heat medium pipes. When water is used, steam from such thermal medium drives a steam turbine to convert solar thermal energy into electric energy.

In addition to the condenser means and thermal medium pipes, such conventional power generator apparatus requires a heat storage tank for storing heat from the thermal medium means, a heat exchanger for transmitting heat from the thermal medium means to water for driving the turbine, and other attachments including a condenser, a cooling water pump, a condensate pump, a feed water pump, control means, and a pressure and heat resisting piping system.

Such apparatus is therefore complicated in construction and the cost of manufacture is high.

Moreover, manipulation is disadvantageously difficult.

When the temperature and pressure in the piping system varies suddenly with variations of solar radiation due to change in atmospheric phenomena, stress is applied to the pressure resisting members, which are susceptible to damage. It is therefore required to provide a special structure for prevention of such damage, thereby further complicating the construction.

In view of the foregoing, there has been developed power generator apparatus in which condenser means condenses rays of sunlight on a plurality of thermoelectric elements disposed adjacent the focus of the condenser means, so that the thermoelectric elements directly convert solar thermal energy into electric energy. Such power generator apparatus eliminates the need for a heat storage tank, a heat exchanger, a pressure and heat resistant piping, etc., which are required in the power generator apparatus of the steam turbine type. It is sufficient to dispose merely the thermoelectric elements adjacent the focus of the condenser means. Such apparatus may be simplified in construction and manipulation, and may be economically manufactured.

According to such power generator apparatus, however, the power generating efficiency of the thermoelectric elements is low, so that solar thermal energy cannot be effeciently utilized. It may therefore be proposed to enlarge the aperture of a reflex mirror or lens, thereby to increase the amount of sunlight to be condensed, or to cool the cold junctions of the thermoelectric elements with the use of cooling water or the like, thereby to provide a great difference in temperature between the cold junctions and the hot junctions of the thermoelectric elements.

The former proposal requires a high-degree technique for machining the reflex mirror or lens. As the apertureof a reflex mirror or lens is increased, the weight of such mirror or lens is considerably increased. It is therefore required to strengthen the structure of support means for supporting the reflex mirror or lens, thereby to reduce practicality disadvantageously.

According to the latter proposal, the great difference in temperature between the cold junctions and hot junctions of the thermoelectric elements may improve the heat generating efficiency of the thermoelectric elements, but the general energy conversion efficiency in the power generator apparatus may not be greatly improved.

According to the invention, there is provided power generator apparatus comprising: a first power generating means including a condensing means for condensing rays of sunlight on the focus of said condensing means and a plurality of thermoelectric elements disposed at or adjacent said focus for receiving condensed rays of sunlight to convert solar thermal energy into electric energy; and a second power generating means including, a main body for receiving cooling water, and warm waste water discharged from said thermoelectric elements having been cooled by cooling water, a drive source made of a shape memory alloy repeatedly deformed and restored due to the difference in temperature between said cooling water and said warm waste water in said main body, and a power generator arranged to be driven to produce electric power by repeated deformation and restoration of said drive source.

The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a front view of power generator apparatus in accordance with a first embodiment of the present invention; Figure 2 is a side view of the apparatus shown in Figure 1,seen from the right; Figure 3 is a plan view of the apparatus shown in Figures 1 and 2; Figure 4 is a distribution diagram of the apparatus shown in Figures 1 to 3; Figure 5 is a block diagram of the apparatus shown in Figures 1 to 4; and Figure 6 is a front view of power generator apparatus in accordance with a second embodiment of the present invention.

Referring to Figures 1 to 3 illustrating a first embodiment of power generating means, front and rear leg members 2a and 2b forming an inverted Vshape are disposed on a square base 1 at its front and rear end portions, and are reinforced by a plurality of reinforcing plates 3. Front and rear bearings 4a and 4b are disposed on both leg members 2a and 2b at their upper ends. A motor 5 for following the sun in the south-north direction is placed on a locating member 6 which is disposed at the upper end of the rear side of the rear leg member 2b. An auxiliary fitting ring 7 is disposed between the bearings 4a and 4b. First and second support shafts 8a and 8b are disposed at the front and rear ends of the ring 7, and are respectively fitted in the bearings 4a and 4b to support the ring 7 rotatably with respect to both leg members 2a and 2b.The second support shaft 8b is connected directly to the rotary shaft of the motor 5.

Left-hand and right-hand bearings 9a and 9b are respectively disposed at the left and right ends of the ring 7. A pair of connection members 10a and 1 Ob have connection portions 11 a and 11 b and extension portions 12a and 12b, which extend in the direction toward the focus of a reflex mirror to be discussed later and which are formed integrally with the connection portions 11 a and 11 bat their upper ends.

A motor 13 for following the sun in the east-west direction is attached outside of the right-hand bearing 9b. Third and fourth supporting shafts 14a and 14b are disposed outside of the connection portions 1 1a and 1 b of the connection members 10a and 10b, and are fitted in the left-hand and righthand bearings 9a and 9b to rotatably support the connection members 10a and 10b with respect to the ring 7.

A reflex mirror 15 is attached to the lower ends of the connection portions 11 a and 11 b of the connection members 10a and 10b. This reflex mirror 15 has a paraboloid for condensing rays of sunlight on the focus of the mirror 15, and an aperture smaller than the diameter of the ring 7.

A cylindrical housing member 16 having a closed top is attached to the upper ends of the extension portions 12a and 12b of the connection members 1 Oa and lob, and is located adjacent the focus of the reflex mirror 15. This housing member 16 is constructed such that cooling water for thermoelectric elements (to be discussed later) flows therein and warm waste water generated when the thermoelectric elements are cooled, is discharged therefrom.

A plurality of thermoelectric elements 17 made of ferrosilicide are housed in the housing member 16 with the hotjunctions of the thermoelectric elements 17 exposed to the lower surface of the housing member 16. These elements 17 are connected in series to each other. Rays of sunlight reflected by the reflex mirror 15 are condensed on the thermoelectric elements 17. A sunlight sensor 18 for following the sun is attached to the upper end of the connection portion 11 b of the right-hand connection member lob. A first power generating means 10 is thus formed by the reflex mirror 15 and the thermoelectric elements 17.

The description will now be made with reference to Figure 4 illustrating a second power generating means.

A main pipe 20 forms a main line for connecting a cooling water tank 21 to an inlet port 22 disposed at the housing member 16. The housing member 16 has an outlet port 23 for discharging warm water heated by heat from the thermoelectric elements 17 when they are cooled by cooling water entering the housing member 16 from the tank 21 through the main pipe 20. An auxiliary pipe 24 has one end connected to the main pipe 20 and forms a branch line. A drainpipe 25 forms a drain line and has one end connected to the outlet port 23.

The main body 26 of a power generating means has at the upper end thereof a cooling water inlet port 27 connected to the other end of the branch pipe 24, and at the lower end thereof a warm waste water inlet port 28 connected to the other end of the drainpipe 25. Although not shown, this main body 26 incorporates a cooling water tank for storing cooling water from the branch pipe 24 at the upper portion of the inside of the main body 26, a warm waste water tank for storing warm waste water from the drainpipe 25 at the lower portion of the inside of the main body 26, and a pair of pulleys having a number of grooves. The main body 26 also incorporates a drive source or drive belt made of a shape memory alloy which is installed between the pulleys.The upper and lower portions of the installed drive belt are respectively immersed in the cooling water and warm waste water tanks, so that the belt is repeatedly deformed and restored due to the difference in temperature between the cooling water and the warm waste in the tanks. The body 26 also incorporates a power generator to be driven by the rotation of the pulleys caused by repeated deformation and restoration of the drive belt. The main body 26, the both tanks, the pulleys, the belt and the power generator thus form a second power generating means 29. Discharge ports 30 and 31 are disposed for discharging the cooling water and the warm waste water in the tanks to the outside of the main body 26. The drive belt arrangement may be similar to that disclosed in our co-pending Application No. (our ref: N372/14/AJMP).

The description will now be made with reference to Figure 5 illustrating the connection in a circuit.

A first voltage regulator 32 has positive and negative input terminals respectively connected to the positive terminal of the first-stage thermoelectric element 17 and to the negative terminal of the last-stage thermoelectric element 17 for maintaining constant the sum of output voltages of the elements 17. A second voltage regulator 33 has positive and negative input terminals respectively connected to the positive and negative output terminals of the power generator in the second power generating means 29 for maintaining constant output voltage of the power generator. A floating battery charger 34 supplies, to load 36 through a feeder 35, a current corresponding to electric powers respectively generated by the power generating means 19 and 29 through the first and second voltage regulators 32 and 33. The floating battery charger 34 always detects electric power consumed by the load 36 and electric powers respectively generated by the power generating means 19 and 29. When the power consumption by the load 36 is smaller than the sum of generated electric powers, the floating battery charger 34 causes a current corresponding to surplus electric power to flow, as a charging current, to a storage battery 38 through a charging line 37. When the power consumption by the load 36 exceeds the sum of generated electric powers, the floating battery charger 34 causes a discharge current of the storage batery 38 to be supplied to the load 36.

The description hereinafter will discuss the operation of the first embodiment discussed hereinbefore.

As shown in Figures 1 and 2, the first generating means 19 is installed such that the first and second support shafts 8a and 8b are disposed in the eastwest direction, while the third and fourth supporting shafts 14a and 14b are disposed in the south-north direction. As shown by long and short dash lines in Figures 1 and 2, rays of sunlight entering the reflex mirror 15 are reflected by the mirror 15 to be condensed on the focus thereof. Rays of sunlight thus condensed are received by the thermoelectric elements 17 disposed adjacent the focus. The hot junctions of the elements 17 are heated to raise the temperature thereof.

Cooling water from the tank 21 through the main pipe 20 enters the housing member 16 to maintain the cold junctions of the thermoelectric elements 17 at low temperatures. A thermoelectromotive force is generated due to the difference in temperature between the hot junctions and cold junctions of the elements 17. The sum of output voltages of the elements 17 or a voltage from the first power generating means 19 is maintained constant by the voltage regulator 32 and is entered into the floating battery charger 34.

Cooling water flowing in the housing member 16 cools the elements 17 and is then heated by heat from the elements 17. Water thus heated is discharged as warm waste water through the outlet port 34. Warm waste water from the outlet port 23 enters the warm waste water tank in the main body 26 through the drainpipe 25 and the inlet port 28.

Cooling water from the tank 21 enters the cooling water tank of the main body 26 through the branch pipe 24 branched from the main pipe 20 and the inlet port 27. The drive belt made of a shape memory alloy installed between a pair of pulleys in the main body 26 is deformed due to the difference in temperature between the cooling water and the warm waste water in the tanks. Such deformation of the belt causes the pulleys to be rotated to drive the power generator. A voltage supplied from the power generator or voltage generated from the second power generating means 29 is maintained constant by the voltage regulator 33 and is then entered into the floating battery charger 34.

When the floating battery charger 34 judges that electric power consumed by the load 36 is smaller than the sum of electric powers respectively generated by the power generating means 19 and 29, a current corresponding to such power consumption flows to the load 36 through the floating battery charger 34 and a load line 35, and a current corresponding to the difference between such power consumption and the sum of electric powers respectively generated by both power generating means 19 and 29 flows, as a charging current, to the storage battery 38to charge the same.

When the floating battery charger 34 judges that power consumed by the load 36 is greater than the sum of both electric powers respectively generated by the power generating means 19 and 29, a current of the total electric power generated by the power generating means 19 and 29 and a discharge current from the storage battery 38 are supplied to the load 36 through the floating battery charger 34 and the load line 35.

The motor 5 is operated according to a signal from the sunlight senser 18 corresponding to variation of the position of the sun, thereby to rotate the first and second support shafts 8a and 8b. The reflex mirror 15 and the housing member 16 are then rotated together with the ring 7 in the southnorth direction. The motor 13 is also operated according to a signal from the sunlight sensor 18 corresponding to variation of the position of the sun, thereby to rotate the third and fourth support shafts 14a and 14b. The reflex mirror 15 and the housing member 16 are rotated together with the connection members 10a and 10b in the east-west direction. Thus, the reflex mirror 15 follows the sun, so that rays of sunlight are always condensed on the thermoelectric elements 17.

In a region adjacent the equator, the first power generating means 19 may be installed as shown in Figures 1 and 2. With such arrangement, the sun may be followed by moving the reflex mirror 15 only in the east-west direction with respect to the movement of the sun in a day. It is merely required at the time of sunrise to rotate the reflex mirror 15 in the south-north direction by a moving angle of the earth's axis for one day. It is therefore possible to shorten the working time of the motor 5 requiring great torque for rotating the reflex mirror 15. Power consumption required for following the sun may be accordingly reduced.

The first embodiment discussed hereinbefore may efficiently utilize warm waste water discharged as heated by the thermoelectric elements 17 when they are cooled, thereby to greatly improve the energy conversion efficiency in converting solar thermal energy into electric energy. The power generator apparatus according to the first embodiment may be simplified in construction and economicaily manufactured as compared with conventional apparatus of the steam turbine type.

Provision of the floating battery charger 34 and the storage battery 38 enables electric power required by the load 36 to be supplied by the power generating means 19 and 29 and the storage battery 38.

Provision of the motors 5 and 13, the support shafts 8a, 8b, 13a and 13b, and the sensor 18 permits the reflex mirror 15 to follow the movement of the sun, thereby to further improve the utilization of solar thermal energy.

The description will then be made of a second embodiment of the present invention with reference to Figure 6.

In this embodiment, there is disposed a reflex mirror 39 long in the east-west direction and having a parabolic section. Support shafts 41 are disposed outside of mounting members 40 located at the front and rear sides of the reflex mirror 39. The support shafts 31 are fitted in bearings 42 on the upper ends of leg members 2a and 2b. The rear-side support shaft 41 is connected directly to the rotary shaft of a motor 43 located behind the rear leg member 2b. Connection members 44 are secured at the lower ends thereof to the mounting members 40. A housing member 45 long in the east-west direction is mounted on the upper ends of the connection members 44. The housing member 45 houses a plurality of thermoelectric elements 17 located on the line connecting the focuses of the reflex mirror 39. There is thus formed a first power generating means 36.The motor 43 may be driven according to a signal from a sunlight senser 47 attached to the rear-side connection member 44 so that the reflex mirror 39 is rotated only in the south north direction to follow the sun.

Instead of ferro-silicide, the thermoelectric elements may be also made of a chalcogens compound or transition metal silicide such as CrSi2, CoSi.

Instead of the reflex mirror 15 or 39, a plurality of small plane mirrors may be arranged in a paraboloid shape or a convex or Fresnel lens may also be used.

According to power generator apparatus of the present invention, there are disposed a first power generating means in which a condensing means condenses rays of sunlight on thermoelectric elements which convert solar thermal energy into electric energy, and a second power generating means in which a power generator is driven to produce electric power by repeated deformation and restoration of a drive source made of a shape memory alloy, such deformation and restoration of the drive source being caused by the difference in temperature between cooling water and warm waste water discharged as heated by the thermoelectric elements when they are cooled.

Warm waste water discharged after the thermoelectric elements have been coiled is thus efficiently utilized. The energy conversion efficiency in converting solar thermal energy into electric energy may be therefore greatly improved as compared with conventional apparatus for producing electric power by only thermoelectric elements. The apparatus in accordance with the present invention may be simpie in construction and economically manufactured as compared with conventional turbine-type apparatus.

Claims

1. Power generator apparatus comprising: A first power generating means including a condensing means for condensing rays of sunlight on the focus of said condensing means and a plurality of thermoelectric elements disposed at or adjacent said focus for receiving condensed rays of sunlight to convert to solar thermal energy into electric energy; and A second power generating means including, a main body for receiving cooling water, and warm waste water discharged from said thermoelectric elements having been cooled by cooling water, a drive source made of a shape memory alloy repeatedly deformed and restored due to the difference in temperature between said cooling water and said warm waste water in said main body, and a power generator arranged to be driven to produce electric power by repeated deformation and restoration of said drive source.

2. Power generator apparatus according to claim 1, wherein the cooling water received by the main body flows in a branch line branched from a main line through which cooling water for the thermoelectric elements flows.

3. Power generator apparatus substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.