SOLAR ENERGY POWERED AIR-CONDITIONING AND REFRIGERATOR SYSTEM

Abstract

A solar powered air conditioner and/or refrigerator system includes a solar absorber heat generator to be exposed to sunlight in communication with a continuous cycle absorption refrigerator inside an adjacent building. Piping connects the out door solar absorber heat generator in fluid communication between the continuous cycle absorption refrigerator and the solar absorber heat generator. Refrigerant grade anhydrous ammonia solution circulates in that piping. A control panel with at least two sensors, an out door thermostat sensor and an indoor thermostat sensor, are in electrical communication. A linear Fresnel lens is located above the solar absorber heat generator to concentrate solar energy. A sun tracker may also be mounted to the Fresnel lens for continuously orienting the Fresnel lens toward the sun to provide maximum solar absorption.

Claims

1. A solar powered air conditioner and refrigerator system, comprising: a solar absorber heat generator to be exposed to sunlight; a continuous cycle absorption refrigerator inside an adjacent building; piping connecting the outdoor solar absorber heat generator in fluid communication; a refrigerant grade anhydrous ammonia solution circulating b in the piping between the solar absorber heat generator and the continuous cycle absorption refrigerator; a control panel in electrical communication with at least two sensors, including an outdoor thermostat sensor and an indoor thermostat sensor; a linear Fresnel lens located above the solar absorber heat generator to concentrate solar energy; and a sun tracker mounted to the Fresnel lens for continuously orienting the Fresnel lens toward the sun to provide maximum solar absorption.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] For a further understanding of the nature and advantages of the expected scope and various aspects of the present invention, reference shall be made to the following detailed description, and when taken in conjunction with the accompanying drawings, in which like parts are given the same reference numerals, and wherein:

[0026] FIG. 1 is a side elevational view of a prior art refrigeration system;

[0027] FIG. 2 illustrates a diagram of the working portions of details of a device made in accordance with the present invention;

[0028] FIG. 3 is a representative drawing of the present invention; and

[0029] FIG. 4 is a block diagram for the programming sequencing of operation of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

[0030] In accordance with the present invention, a new air-conditioning and/or refrigeration system is disclosed that utilizes solar energy for air conditioning or refrigeration by heating an ammonia-based refrigeration fluid in a continuous cycle absorption mode to generate cold air. Further, the disclosed invention does not use a compressor to generate cold, thereby eliminating the need for electricity to operate a compressor.

[0031] In its most basic form, the present invention creates cold air, and by its unique structure and methods of use, this cold air can either be used to provide chilled air blown into a room for air conditioned personal comfort, or the chilled air may be kept in a small compartment to act as a refrigerator or freezer for food storage, medical supplies, or any other typical use for a lower temperature environment.

PRIOR ART

[0032] Referring now to the drawings in detail, FIG. 1 is a representative diagram of the workings of a prior art combined cycle absorption refrigeration system, where no moving parts were employed. This refrigeration mechanism is based on Dalton's law, PV=nRT. Combined cycle absorption refrigerators are commercially available nationwide particularly for use in domestic refrigerators and recreational vehicles.

[0033] These prior art absorption cooling units generally consist of four main parts: a boiler, a condenser, an evaporator and an absorber. Conventionally, this type refrigerator unit burns some type of fossil fuel, whether it be gas, kerosene or propane. The fuel is supplied to burners to heat refrigerant working fluids in the absorption cooling unit. Typically, the unit is charged with a refrigerant fluid of ammonia, water and hydrogen. The amount of ammonia is predetermined to be at a sufficient ammonia condensing pressure at or around room temperature. When heat is supplied to the system, the temperature of the ammonia solution rises, and boils to create ammonia solution gas which evaporates and rises through a pump.

[0034] Generally, the ammonia solution rises into the evaporator and the water separator. In the water separator, water vapor condenses and runs back down into the system, leaving the dry vapor ammonia in the condenser. As air circulates over the condenser plates, heat is removed from the ammonia vapors, condensing to a liquid ammonia. This liquid ammonia then enters the evaporator and hydrogen gas is introduced. Typically, the hydrogen gas arises from the surface of the ammonia, and the hydrogen gas lowers the partial pressure of ammonia vapors enough to persuade the ammonia to evaporate. When the ammonia evaporates, heat is extracted from the evaporator. In turn, heat is extracted from the space being cooled whether it is a refrigerator to store food or cold air being blown into a room to act as an air-conditioner.

[0035] Continuing on with the cycle, a mixture of ammonia, hydrogen, and vapors pass from the evaporator to the absorber. indoor this combined cycle, a continuous stream of the ammonia solution comes into the upper part of the absorber, as it is supplied by gravity. This ammonia solution flows through the absorber and comes in contact with the mixed ammonia and hydrogen gases. Hydrogen gas is free to ride through the absorber and is then returned to the evaporator. As one can see, hydrogen gas continuously circulates between the absorber and the evaporator, while a stronger solution of ammonia produced in the absorber flows into the absorber vessel. Thereafter, this newly formed stronger solution of ammonia produced in the absorber enters the boiler system to complete the full cycle of operation. This cycle runs continuously until the boiler is heated by the heat generator which controls a thermostat that governs the heat source and regulates the temperature of the refrigerated space.

[0036] As one who is familiar with such an ammonia refrigerant working fluid, it must be realized that extremely low temperatures are produced by the fluid. These low temperatures are transferred to make cold air by moving ambient air around Besides the thermostatic controls and fan motor (s) there are essentially no other moving parts.

[0037] Looking still to FIG. 1, we are looking at a prior art refrigeration system having a generator 12 in thermal communication with a boiler 14. Refrigerant grade anhydrous ammonia gas 18 is resident in the boiler 14 and is pumped by pump 19 up into separator 16 flowing into condenser 20 and mixing with hydrogen gas found in tube 21. The mixture of ammonia gas and hydrogen gas flow into evaporator 24 through gas temperature exchanger 22. Some of this mixture flows down into absorber 26 which is cool enough to deposit liquid into absorber vessel 28. After collection in absorber vessel 28 the liquid flows downward through a liquid temperature exchanger back into boiler 14.

PRESENT INVENTION

[0038] Looking next to FIG. 2, the present invention shows a new use for the prior art refrigeration system when combined with a novel solar powered heat generation source for heating the ammonia solution to make the combined cycle absorption system operate without much electricity. These new features yield an unexpectedly good result of a solar powered air conditioning and/or refrigeration system that uses very little electricity. With the use of a particular type of optimize Fresnel lens for concentrating solar rays, and tracking the sun with a sun tracker, a novel system is achieved.

[0039] FIG. 2 diagrammatically shows a first aspect of the present invention disclosing a new solar powered air-conditioning/refrigerator system, generally denoted by numeral 40. Solar powered air-conditioning and/or refrigeration system 40 includes at least two parts, an outdoor heat generator 42, and an indoor unit in thermal communication with the outdoor unit by a refrigerant grade anhydrous ammonia solution flowing therebetween in pipes 44. Pipes 44 are in thermal communication between the outdoor heat generator and the indoor unit, preferably embedded within heat generator 42 such that when heat generator 42 is warmed by sunlight, heat generator 42 reaches a temperature above the boiling point of the refrigerant grade anhydrous ammonia solution ammonia-based working fluid, it imparts that temperature by conduction to the ammonia-based fluid within pipes 44 and the ammonia-based fluid boils and moves through pipes 44. The heated refrigerant grade anhydrous ammonia solution flows through pipes 44 into a separator 46 and then rises up to condenser 48. Once separated, an ammonia concentrate is formed, and the ammonia concentrate flows down into freezer pipes 52 within freezer space 54. High purity ammonia is helpful to ensure proper function of the refrigeration system.

[0040] Condensed water from the operation of the system is essentially distilled water and may either be collected or discarded. A water spout from the bottom of the indoor unit (not shown) could easily be directed into a sterile container for potable water needs.

[0041] A suitable heat generator 42 is preferably a boiling tank made from steel or aluminum alloy of ammonia corrosion-resistant and high temperature resistant materials that exhibit a minimal Coefficient of Thermal Expansion. The metal should remain dimensionally stable from 100 C. to 600 C., depending on the required BTU capacity of the installation. The metal used to make the boiling tank should not be able to be corroded by the ammonia-based fluids that will be contained therein.

[0042] Still referring to FIG. 2, freezer space 54 is located on top of refrigerator space 65. As mentioned above, the chilled air is either in an air conditioning mode where the chilled air is blown into a room for personal comfort, or it is contained within a freezer compartment to yield a cooled air space for cooling or freezing its contents. In the air conditioning mode, fan 58 heat exchanges the cold air from freezer space 54 and blows cold air 60 out into an adjacent room to air-condition the room. Alternatively, if one would prefer to keep the cold in a freezer space of a refrigerator, there would be either a very small fan or no fan at all, and the cold air would flow within the refrigerator. In this aspect of the invention as shown in FIG. 2, hot air 62 enters into refrigerator 56 through an air filter 64 where the hot air rises through refrigerated space 65 into freezer space 54, where the hot air is cooled down by coming into thermal contact with freezer pipes 52 and is cooled.

[0043] Looking next to FIG. 3, there is shown a representative drawing of the present invention. A refrigeration unit, generally denoted by 70 again is shown as having at least two parts. The first part is the heat generator 72 which is located outdoors exposed to sunlight. The refrigeration unit 70 is inside the building and is in thermal communication with heat generator 72 by in and out piping, including liquid lift pipe and liquid return 74 and 76, respectively. In operation, heat generator 72 warms up ammonia solution carried therewithin and that heated ammonia solution is then transported to refrigerator 78 by liquid lift pipe 74. The ammonia solution is then processed as shown in FIG. 2 within refrigeration unit 78. As we saw before with reference to FIG. 2, hot air 84 enters refrigerator unit 78 through an air filter 86. After processing, fan 80 ejects cold air 82 into the room where refrigerator 78 is located.

[0044] However, as one can imagine, the sun does not always shine. In order to provide constant operation at night or on extremely cloudy days, an optional conventional burner 100 with a source of propane, kerosene or other fuels may be implemented. As one can imagine, heat generator 72 does not always receive full sunlight impinged onto its surface. In order to make this system more efficient, a Fresnel lens 90 may be used to concentrate available sunlight onto heat generator 72. In particular, in order to avoid spot heating, a linear Fresnel lens is found to be particularly useful, especially when it is directed toward the sun at an optimal angle by a motorized sun tracking system 94. Such a commercially available sun tracking system 94 would be optimally moved by a motorized mechanical means directed by a computer or a control panel 96. The control panel 96 is in electrical communication with the fan 84 and is programmed to synchronize between the indoor unit and the outdoor unit to the motor of the sun tracker 94.

[0045] In order to regulate the temperature needs of the comfort level for air conditioning in a room or for generating a suitable temperature freezer compartment, two thermostat sensors are most helpful. The first sensor 63 is located in the indoor unit in air filter 64 for sensing the incoming temperature of air, while the second sensor is an outdoor thermostat 43 within heat generator 42 to measure the temperature of the metal heat generator 42. The second sensor may be a thermocouple, providing information and signals back to the indoor thermostat 63. This information then regulates the fan 58 to either speed up to a High position or slow down to a Low position to achieve the desired temperature. Conventional thermocouples may be employed to measure temperatures and give appropriate signals.

[0046] Further, a sun tracking system 94, may be used to help locate and orient Fresnel lens 90 into a proper position for maximum sunlight capture onto heat generator 72. Sun tracker 94 may utilize a small amount of electricity to orient Fresnel lens 90 to concentrate the maximum amount of photons onto heat generator 72.

[0047] Although the present invention uses solar energy for solar absorption in the heat generator in the various aspects, this system still requires a small amount of electricity to operate the fan and the sensors, as well as the optional motorized sun tracker system. In order to provide this amount of electricity, the present system shall be in electrical communication with the local electrical grid or a sustainable battery pack sufficiently charged to provide enough electricity. In the event that a battery is used for off-the-grid locations, the battery may be charged by an auxiliary photovoltaic solar panel.

[0048] Now we review the solar energy source for operating the solar powered heat generator of the present invention. Heat generator 72 may be made of any suitable heat-collecting material, but is preferably made of a heavy metal, such as iron or steel for durability and heat capacity. While iron or steel will work without any further enhancements, such a metallic heat generator may be most preferably coated with a dark surface for collecting maximum amount of heat from the solar energy. A liner may be utilized to prevent the metal outer shell of the tank from coming into contact with the highly corrosive ammonia-based solution that the tank contains and heats. Preferable materials used for the heat generator include high thermal absorption and high heat capacity metals and/or stones, such as granite, and especially ones that are coated with heat absorbing coating materials. Although a stone heat generator may be fragile or brittle, once it is in place, one may find an advantage to using such a heat generator material. Appropriate metals may include iron of various sorts, steel, and/or other high heat capacity metals. In particular, coatings on the metal or stone heat generator substrates may be as simple as black paint or as complicated as plasmonic solar-absorbing coatings with high surface area upwardly extending whiskers.

[0049] A preferred type of thermal coating may be advantageously applied onto the sun facing surfaces of the heat generator tank. Such a thermal coating may include black paint coated on the heat generator acting as a solar collector absorber. Preferable coatings include a flat black thermal paint, tested with a near direct incidence of sun as well as with an azimuth angle of sunshine at about 45 degrees. A suitable thermal paint is preferably provided as a fully opaque coating of about 5 mm to 20 mm thick. A preferred paint is Rust-Oleum flat black high temperature barbecue paint, commercially available from Rust-Oleum Company of Vernon Hills, Ill. in addition, another possible coating is Thurmalox Solar Collective Coating 250 Selective Black, commercially available from Dampney Co., Inc. of Everett, Mass. Experimental results showed a consistently high temperature at the surface of a painted metallic heat generator of 155.4 F. (68.5 C.) with a paint thickness of about 10 mm, for near direct incidence of sun. In tests done at an azimuth angle of about 45, the flat paint averaged a surface temperature of 153.6 F. (67.5 C.).

[0050] The ammonia solution best employed in various aspects of the invention is preferably a refrigerant grade anhydrous aqueous ammonia solution having from about 25% to about 35% by volume of anhydrous ammonia, balance of water, yielding an ammonium hydroxide solution. As the boiling point of a preferred 30% by volume ammonia solution is only 33 C. (91 F.), it is clear that vaporizing of the ammonia solution will occur when the temperature of the heat generator at direct sun incidence was 68.5 C., quite a bit higher than the boiling point of the ammonia solution. When the sunlight incidence was at an azimuth angle of about 45 degrees, a surface temperature of the heat generator was 67.5 C., which is sufficiently hot to make the present solar powered air-conditioning/refrigeration system operate.

[0051] The liquid lift piping 74 is preferably made of a metal type pipe with a coating of anti-corrosive thereon. Preferably, said piping 74 would be made of copper, galvanized steel or aluminum, and most preferably made of copper pipe.

[0052] FIG. 4 is a block diagram showing the steps for a method of using and operating the present invention, beginning with activating the indoor unit control panel to regulate the desired temperature. An operator will then set the desired room or refrigerator compartment temperature, which also sets the electrical fan regulator. Once the fan regulator is set, a signal is sent to the control panel. The control panel is in communication with both the outdoor thermostat sensor and the indoor thermostat sensor. If the indoor thermostat sensor measures that the temperature of the room or the refrigerator space is hot, and the outdoor thermostat sensor indicates that the heat generator is hot, a timer is actuated that turns on the electrical fan to distribute cold air. On the other hand, if the indoor thermostat sensor measures that the temperature of the room or the refrigerator space is hot, but the outdoor thermostat sensor indicates that the heat generator is too cold, a signal is sent to the motorized sun tracker which will shift location to orient the Fresnel lens into position to concentrate more sunlight onto the heat generator. Once the heat generator rises to the appropriate temperature to begin the continuous cycle absorption, cool air will be forthcoming. The timer will be activated, and electrical signals will be sent to the fan, which ultimately regulates the temperature of the desired space.

[0053] Now we will review the other components of the present invention which add efficiency and provide the optimal amount of coolness to a desired location. Once again, the present invention uses solar energy to produce coolness, and that coolness can either be used to cool a room for personal comfort by being blown into the room by the fan. Or, in the alternative, the coolness may be kept in a freezer space and used to cool food or other items.

Fresnel Lens

[0054] In order to achieve maximum efficiency for the present invention, an optional addition to the system may be a Fresnel lens, preferably mounted on a sun tracker system to constantly align the Fresnel lens in an optimum position with relation to the sun.

[0055] Generally, there are two types of Fresnel lens, as the main common types are either linear Fresnel lens or spot Fresnel lens. Spot lenses are probably ineffective for most applications with the present invention because they would concentrate too much sunlight onto one spot and superheat the ammonia solution. Spot lenses are capable of concentrating sunlight to achieve approximately 1500 F. at its focal point while a Linear lens is usually only capable of achieving approximately 200 F. at its focal point. On the other hand, a linear Fresnel lens would be able to regulate the necessary amount of sunlight to achieve a workable operating temperature. While a man can put his hand under a Linear lens exposed to sun light, and it may feel warm or hot, a Spot lens can burn flesh, start fires and might even melt steel used as the heat generator.

[0056] For the present invention, a Linear Fresnel lens is most advantageous, providing a workable system from about 2400 BTU up to 3600 BTU, thereby matching the capacity of continuous cycle absorption systems commercially available in the market. In contrast, it is possible to reach 6000 BTU using a continuous cycle absorption system with modifications to the size of the evaporator, the condenser, and the fan along with modifications to the size of the ventilation openings.

Sun Tracker

[0057] In practicing the present invention, a sun tracker may be advantageously mounted to the Fresnel lens to maximize efficiency, In accordance with the present invention, various commercially available solar tracking mechanisms may be modified to orient the Fresnel lens onto the heat generator without undue experimentation. The sun tracker will receive electronic signals to change its orientation throughout the day to follow the sun's path to maximize energy capture. Sun trackers help minimize the angle of incidence, ie. the angle that a ray of light makes with a line perpendicular to the surface of the Fresnel lens between the incoming light and the Fresnel lens, thereby increasing the amount of energy the installation produces. Sun trackers must be angled correctly to orient the Fresnel lens.

[0058] Single-axis solar trackers rotate on one axis moving back and forth in a single direction. Different types of single-axis trackers include horizontal, vertical, tilted, and polar aligned, which rotate as the names imply. Dual-axis trackers continually face the sun because they can move in two different directions. Types of suitable dual axis trackers may include tip-tilt or azimuth-altitude trackers. Dual-axis tracking may be advantageously used to orient the Fresnel lens and redirect sunlight along a fixed axis towards the stationary heat generator receiver. Because these dual axis trackers follow the sun vertically and horizontally, they help obtain maximum solar energy absorption.

[0059] There are also several methods of driving solar trackers. Passive trackers move from a compressed gas fluid driven to one side or the other. Motors and gear trains direct active solar trackers by means of a controller that responds to the sun's direction. Finally, a chronological type tracker can counteract the Earth's rotation by turning in the opposite direction.

Indoor Thermostat Temperature Sensor:

[0060] The function of the indoor thermostat temperature sensor is to control the room temperature required by the user. The location of the thermostat sensor is in air filter of the Indoor unit, and is exposed to the hot air that comes from the ambient air in the room. Either of two types of sensors; manual and digital electronic thermostats may be utilized.

[0061] Air conditioning thermostats have either bi-metal units, as in older thermostats or thermistors, as found in newer thermostats. These thermostats sense the air current returning to the return ducts or the surrounding air.

[0062] For example, if the unit is in heat mode and the temperature is set at 70 F., the air conditioning thermostat senses the ambient room air currents and the air current temperature is 65 F. The heater will run until it picks up the ambient air current reading 70 F. at which time it will stop running. All HVAC thermostats work on this same principle. Regardless if it is a digital thermostat, programmable, talking thermostat, telephone thermostats or zoning thermostat, it will rely on the ambient air temperature to work.

Outdoor Thermostat Temperature Sensor

[0063] The outdoor thermostat temperature sensor has the same function as the indoor thermostat temperature sensor. This type is always used in electrical heaters.

[0064] Location of the outdoor thermostat temperature sensor is at the body of the generator metal outdoors. The function of the outdoor thermostat temperature sensor is that it controls the temperature of the metal body of the heat generator. The amount of sunlight that impinges on the heat generator metal might be very high, so much so that it might melt the metal. The melting point of the metal used for the generator metal is already known from the specification of its physical properties.

Electronic Control Panel

[0065] In contrast, if the air conditioning unit is turned on, the electronic control board-programmed panel will check to see whether the generator is hot enough or not for operation. If it is not hot enough, then it sends an electronic signal to order the sun-tracker to search for sunlight, and if it is hot enough to operate the A/C then the fan will operate. The fan regulator can be switched on to automatic mode or manual mode. The automatic mode let the electronic control board-programmed panel give the correct level of the regulator with the required room temperature.

[0066] The function of the electronic control board-programmed panel is to synchronize all the following parts together: Indoor Thermostat Temperature Sensor, Out-door Thermostat Temperature Sensor, Fan and the electrical motor of the sun tracker. After receiving digital read-outs of the indoor and the outdoor sensors, signals are sent to the fam and the electrical motor of the sun tracker.

EXAMPLE 1

[0067] In a room of length 4 meters, width 3 meters, and height of 3 meters, a 2400 BTU solar powered continuous cycle absorption system was operated with a full sunny day, and the shed temperature is 30 C. The required BTU is about 2400. A fan-less Sun Frost propane refrigerator, with a consumption rate normally of 1.5 pounds or 0.375 gallons/day of propane is modified to add a fan out of the freezer space and longer pipes to move an ammonia-based solution in and out of the Sun Frost refrigerator between the refrigerator inside the room and a heat generator boiling tank out-of-doors and set out in the sun. After about 20 minutes, the boiling tank was hot enough to boil the ammonia-based solution. The newly added fan blew cold air out into the room and was able to compare favorably with a 2400 BTU conventional air conditioner.

[0068] In summary, numerous benefits have been described which result from employing any or all of the concepts and the features of the various specific aspects of the present invention, or those that are within the scope of the invention. The solar powered air conditioner or refrigerator acts as a low energy requiring, non-compressor using system particularly useful for sunny climates.

[0069] The foregoing description of a preferred aspect of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings with regards to the specific aspects. The aspect was chosen and described in order to best illustrate the principles of the invention and its practical applications to thereby enable one of ordinary skill in the art to best utilize the invention in various aspects and with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims which are appended hereto.