WINDOWS FOR PRODUCING ELECTRICITY FROM SOLAR ENERGY

A system for producing electricity from solar energy is provided. The system includes a window pan for installing on building such that solar radiation impinges thereon, a heat receiving element coupled to the window pan and being configured to receive heat from the solar radiation. The system further includes a gas line thermally coupled to the heat receiving element with a heat transferring member the gas line having a liquid gas being configured to evaporate by the heat generated by the heat receiving element and to increase thereby pressure in the gas line. The system further includes a turbine having a rotor configured to convert rotating motion to electricity, the turbine being configured to receive evaporated gas from the gas line and the evaporated gas is configured to rotate the motor.

FIELD OF INVENTION

The presently disclosed subject matter relates to a system for producing electricity from solar energy in general, and in particular to a system for integration in windows.

BACKGROUND

The market for alternative power production using renewable sources is growing owing to advances in materials, the tremendous reduction in costs of such systems, and the growing desire to use means other than fossil fuels. The most plentiful of these resources is the Sun and there are several ways to generate electricity making use of it. Currently, the lowest cost of these is to devise a system using PhotoVoltaic (PV) panels.

Here, electrical energy will be produced cheaper than any other means of exploiting the Sun. However, when combined with the additional need of hot water (all domestic dwellings and a very large percentage of commercial, and virtually all industrial centers), a different system is more cost effective.

SUMMARY OF INVENTION

There is provided in accordance with an aspect of the presently disclosed subject matter a system for producing electricity from solar energy. The system includes a window pan for installing on building such that solar radiation impinges thereon, a heat receiving element coupled to the window pan and being configured to receive heat from the solar radiation. The system further includes a gas line thermally coupled to the heat receiving element with a heat transferring member the gas line having a liquid gas being configured to evaporate by the heat generated by the heat receiving element and to increase thereby pressure in the gas line. The system further includes a turbine having a rotor configured to convert rotating motion to electricity, the turbine being configured to receive evaporated gas from the gas line and the evaporated gas is configured to rotate the motor

The heat receiving element is a copper plater disposed along a portion of the window pan. The gas line extends along an edge of the copper plate to receive heat therefrom and further extends away from the window pan towards the turbine.

The gas can be configured to shift between a liquid state and a gaseous state, and wherein the gas is shifted from liquid state to gaseous state as a result of the heat from the heat receiving element. The gas can be freon.

The heat receiving element can be a copper plater disposed along a portion of the window pan and the pipeline extends along the copper plate.

The heat transferring member can include a pipeline coupled to the heat receiving element and a liquid container, the pipeline can be configured to transfer thermal conductive liquid to the liquid container and the gas line extends through the liquid container such that gas in the gas line is heated by the thermal conductive liquid.

The gas line can be in a form of a spring increasing thereby the path of the gas pipe inside the container.

The window pan can include two pan defining therebetween an inner space and wherein the heat receiving element is disposed inside the inner space. The inner space can include thermo liquid configured to retain heat when no solar radiation is available.

The system can further include a liquid pump for forcing the liquid gas towards the window pan.

The system can further include a cooling device configured to cool off the gas from the turbine so as to shift the gas to the liquid state thereof. The system can further include a heat exchanger configured to receive heated gas from the turbine and liquid gas from the cooling device and being further configured to exchange heat between the heated gas and the liquid gas, the heat exchanger is configured to feed the liquid gas back towards the heat transferring member and to preheat the liquid gas before entering the heat transferring member.

DETAILED DESCRIPTION OF EMBODIMENTS

FIGS. 1 and 2show a system10for producing electricity from solar energy, the system includes a window pan12for installing on building (not shown) such that solar radiation impinges thereon. The window pan12according to an example can be a fully transparent window configured to allow sunlight to be transfer to the building, such that the window serves as a regular window allowing sunlight into the building. According to another example the window pan12can be coated with a filtering layer allowing only some of the radiation through the window pan.

The system further includes a heat receiving element14coupled to the window pan12and being configured to receive heat from the solar radiation. According to the illustrated example the window pan12includes two pans disposed in parallel with each other and defining an inner space16therebetween. The heat receiving element14is disposed in the inner space16and is configured to collect heat from the solar radiation. According to the illustrated example, the heat receiving element14is a metal plate, such as copper, configured to absorbed heat from the solar radiation. It is appreciated that the size of the metal plate can be smaller than the size of the window pan12. That is to say, since the metal plate blocks light of the solar radiation, the metal plate14can be disposed only at a certain portion of the window pan12leaving other portions of the window pan12exposed, allowing thereby sunlight to enter the building.

According to an example the inner space16has vacuum, facilitating thereby heat retention in the window pan12.

The system further includes gas line20thermally coupled to the heat receiving element14with a heat transferring member22. The gas line20according to the illustrated example is disposed along one edge of the metal plate14, and is coupled thereto by heat transferring member22which according to the illustrated example are metal coupling members transferring heat accumulated in the metal plate14towards the gas line20.

The gas line20includes a liquid gas which is heated by the heat generated by the heat receiving element14. The gas is selected such that its thermodynamic properties allow the gas to evaporate by the heat generated by the heat receiving element14and to increase thereby pressure in the gas line. I.e., the gas is selected such it shifts in the system between liquid state and gaseous state, thereby providing pressure gradient. In other words, the gas is selected such that the evaporating points thereof is at a temperature which can be achieved by the heat from the heat receiving element14. This way, when the temperature of the gas is below evaporating points the gas is in its liquid state. The gas line20extends out of the window pan12away from the heat receiving element14such that gas in portions of the gas line20which are not in contact with the heat receiving element14cools off. As a result, the gas can be heated by the metal plate14to its evaporating point increasing thereby the pressure in the pipeline and when the gas is transferred away from the window pan12the gas is cooled off back to its liquid state.

Moreover, it is desired to use gas which has a relatively high PSI difference between its liquid state and gaseous state, such that shifting the gas to its gaseous states provides high pressure. More particular, in order to provide sufficient energy which can be converted to electrical energy is it desired that the pressure obtained in the gaseous state provides an additional 100 PSI, which can be utilized to operate a generator. For example, it is desired that when the gas is converted to its gaseous state the pressure is at least 300 PSI and when in the liquid state the pressure is 200 PSI. This way, the generator can consume 100 PSI for generating electric energy.

Moreover, since the system requires that the gas is converted from its liquid state to its gaseous state, after the gas had operated the generator, the gas must be converted back to its liquid state so as to allow another cycle of shifting from liquid state to gaseous state. The latter is achieved by cooling the gas to its condensing temperature. In order to avoid investing energy in cooling the gas to its condensing temperature, the gas is selected such that its condensing temperature is reached under the pressure at the exit of the generator. In other words, the condensing temperature of each gas depends on the pressure in the system, thus, since the generator reduces the pressure, the gas can be selected such that reduction in pressure facilitate brining the gas to its condensing temperature.

An example of such gas is Freon Refrigerant—R422 which has an evaporating temperature of 70° Celsius, and its condensing temperature is 38° Celsius at 200 PSI. Freon Refrigerant—R422 further has an expansion coefficient gas which provides high pressure of 300 PSI and more when the gas is converted to its gaseous state.

Thus, the Freon Refrigerant—R422, reaches 300 PSI when evaporating, and after exiting the generator when the gas is at 200 PSI, the gas needs to be cooled off only to 38° Celsius in order to be converted back to liquid. This way, simple means can be used to cool off the gas, such as a radiator, and not much energy is required for cooling the gas.

The system10further includes a turbine25having a rotor28configured to convert rotating motion to electricity. The turbine25is coupled to the gas line20and is configured to receive evaporated gas from the gas line20such that the evaporated gas rotates the rotor. By way of example, the pressure of the gas when entering the turbine is 300 PSI and when exiting the turbine it is 200 PSI. Thus, the turbine converts 100 PSI to electrical energy.

The gas line further extends from the turbine back to the window pan12forming a close loop. It will be appreciated that since the energy provided by the gas is formed by conversion of the heat to pressure, it is desired to have the gas shifting between gaseous state and liquid state, such that when the gas is converted to its gaseous state pressure in the gas line rises. In order to maximize the energy produced by the gas, it is desired to shift the gas exiting the turbine25from the gaseous state back to its liquid state, such that the liquid gas can be fed back to the window pan and be heated again. Thus, while the energy from the pressurized gas is utilized for motorizing the rotor, pressure in the gas line exiting the turbine25is reduced and consequently, the temperature of the gas is lowered. It is however required that the gas is further cooled off to a temperature lower than the evaporating point of the gas, so the gas is shifted back to its liquid state. For that the system can include a cooling device35such as a radiator or other cooling system such as cannot cycle etc.

The gas is then fed back to the portion of the gas line20attached to the metal plate14such that the gas is heated again by the metal plate14shifting the gas again to its gaseous state and allowing another cycle of the pressurized gas towards the turbine25.

Since the liquid gas entering the window pan is under a lower pressure than the gas in its gaseous state, a liquid pump38may be used so as to force the liquid gas towards the metal plate14.

The system thus produces thermal energy without consumption of expensive resources and allows reaching high temperature such that the required energy level is available.

The system can further include thermo liquid30disposed in side the inner space16, so as to accumulate the heat of the solar radiation. The thermo liquid30, which can be oil, is configured to maintain the heat accumulated during the day light hours and to heat the metal plate14when no solar heat is available. This way, the system10produces electricity even when there is no immediate solar radiation.

The system thus provides means for energy accumulation, instead of utilizing batteries and the like to store electrical energy the windows store thermal energy and the system converts the thermal energy to electric energy. It is appreciated that the thermo liquid can be configured such that it retains the temperature for the duration of time in which there is no solar radiation, i.e. the hours of the night. The thermo liquid can be further configured to heat the gas to the required temperature so as to convert the gas from its liquid state to gaseous state.

FIGS. 3 and 4show another example of a system50for producing electricity from solar energy, the system includes a window pan52for installing on building (not shown) such that solar radiation impinges thereon. The window pan52according to an example can be a fully transparent window configured to allow sunlight to be transfer to the building, such that the window serves as a regular window allowing sunlight into the building.

The system50further includes a heat receiving element54coupled to the window pan52and being configured to receive heat from the solar radiation. According to the illustrated example the window pan52includes two pans disposed in parallel with each other and defining an inner space56therebetween. The heat receiving element54is disposed in the inner space56and is configured to collect heat from the solar radiation. According to the illustrated example, the heat receiving element54is a metal plate, such as copper, configured to absorbed heat from the solar radiation. It is appreciated that the size of the metal plate can be smaller than the size of the window pan52. That is to say, since the metal plate blocks light of the solar radiation, the metal plate54can be disposed only at a certain portion of the window pan52leaving other portions of the window pan52exposed, allowing thereby sunlight to enter the building.

According to an example the inner space56has vacuum, facilitating thereby heat retention in the window pan52.

The system further includes a heat transferring member62, which according to the illustrated example is a pipeline extending along the metal plate54, and having liquid configured to absorbed heat from the metal plate54. According to the illustrated example the pipeline62extends along an undulated path, so as to increase the length of the path of the pipeline along the metal plate54increasing thereby the exposure of the thermo pipeline62to the heat of absorbed by the metal plate54.

The pipeline62extends out of the window pan52toward a liquid container64transferring the heated liquid thereto. The container includes gas line66having a liquid gas which is heated by the liquid inside the container64. The pipeline62, the container64and the liquid therein thus serves as a heat transferring member for transferring heat from the metal plate54to the gas line66. The gas line66inside the container acts as a heat exchanger, heating the liquid gas and cooling off the liquid in the container64. The pipeline extends from the container back towards the window pan52in a close loop to heat the liquid again. To facilitate the flow of the liquid in the pipeline62especially the cooled off liquid entering the window pan42, a liquid pump68can be integrated in the pipeline62.

The gas line66according to the illustrated example is in a form of a spring, increasing thereby the length of path inside the container64and providing a better heat exchange between the liquid in the container64and the gas in the gas line66.

As in the example ofFIGS. 1 and 2, the gas line66includes a liquid gas which is heated by the liquid inside the container64. The gas is selected such that its thermodynamic properties allow the gas to evaporate by the heat in the container64and to increase thereby pressure in the gas line. I.e., the gas is selected such it shifts in the system between liquid state and gaseous state, thereby providing pressure gradient. In other words, the gas is selected such that the evaporating points thereof is at a temperature which can be achieved by the heat inside the container64. This way, when the temperature of the gas is below evaporating points the gas is in its liquid state.

The system50further includes a turbine75having a rotor78configured to convert rotating motion to electricity. The turbine75is coupled to the gas line66and is configured to receive evaporated gas from the gas line66such that the evaporated gas rotates the rotor78.

The gas line further extends from the turbine back75back to the container64forming a close loop. Thus, while the energy from the pressurized gas is utilized for motorizing the rotor, pressure in the gas line exiting the turbine75is reduced and consequently, the temperature of the gas is lowered. The gas is then heated again by the liquid in the container64further pressurizing the gas and allowing another cycle of the gas towards the turbine75.

The gas line66extends out of the container64such that gas in portions of the gas line66which are not in contact with the liquid inside the container64cools off. As a result, the gas can be heated by the heat transfer from the metal plate54to its evaporating point increasing thereby the pressure in the pipeline and when the gas is transferred away from the container64the gas is cooled off back to its liquid state. It is however required that the gas is further cooled off to a temperature lower than the evaporating point of the gas, so the gas is shifted back to its liquid state. For that the system can include a cooling device80such as a radiator or other cooling system such as cannot cycle etc. Furthermore, a gas liquid pump82may be used so as to force the liquid gas towards the container64.

Finally, as in the example ofFIGS. 1 and 2, the system50can further include thermo liquid85disposed in side the inner space56, so as to accumulate the heat of the solar radiation. The thermo liquid85is configured to maintain the heat accumulated during the day light hours and to heat the metal plate54when no solar heat is available. This way, the system50produces electricity even when there is no immediate solar radiation.

By way of example, power required per square meter on a single floor in a tall building is 16 W/m2, and for a floor of 2500 m2the required energy is 40 kW.

The power available from the sun is 600 W/m2and considering a 60% efficiency of the collectors, in order to provide 40 kW collectors in an area of 110 m2are required.

It is appreciated that the above process, which is in essence a Organic Rankine Cycle (hereinafter ORC), maybe further improved so as to enhance its efficiency.

One method of improving efficiency is to recover energy not used by the turbine and return it to the system rather than losing it in the cooling device. Note that if an ORC is, for example 16% efficient, it means that 84% of the energy is being lost. It is the purpose of heat recovery to try to capture a fraction of this lost energy.

In the process, the gas leaving the turbine immediately enters the cooling device, such as a chiller. According to an example, illustrated inFIG. 5, a heat exchanger110can be placed between the turbine105and the chiller112in which the gas leaving the turbine105enters the heat exchanger110before going to the chiller112. The heat exchanger110is further connected to the pump115which receive the cooled gas from the chiller112and forces it bac into the heat exchanger110.

Thus, while the gas entering the heat exchanger110from the turbine105has an elevated temperature the cooled gas entering the heat exchanger110from the chiller112is at a lower temperature. Thus the cooled gas, which is already in its liquid phase, upon becoming in contact with the warmer gas will heat up, thus capturing some of the otherwise lost energy. This reduces the amount of energy then required to elevate the temperature of the liquid to boiling and to accomplish the phase change which would otherwise be done by the heat from the window pan. This then requires the heat from the window to give up less energy on each pass of the liquid through it in order to get to the driving conditions for the turbine and improves the overall efficiency.

As shown in the illustrated example, the heat exchanger110includes sections102a,102b,104aand104b, which correspond to various conditions of the gas inside the heat exchanger. The station102ais where the heated gas from the turbine105enters the heat exchanger110and is cooled enough to begin liquifying. Station102bis the final condition of the working fluid after it leaves the heat exchanger before entering the chiller112. Station104ais where the liquid from the pump115within the heat exchanger110has absorbed enough energy to reach its evaporation temperature and begins to evaporate. Station104bis the final state of the working fluid as it leaves the heat exchanger before entering the tank.

Those skilled in the art to which the presently disclosed subject matter pertains will readily appreciate that numerous changes, variations, and modifications can be made without departing from the scope of the invention, mutatis mutandis.