Abstract:
Solar-powered shielding mechanism is disclosed. The mechanism includes a shield, a pair of tracks, an energy collecting device for collecting solar energy, storage for storing liquid being heated in the energy collecting device, and a motor powered by electricity generated by a power generator converting heat from the liquid being heated by the energy collecting device. The motor is operated to retract or extend the shield along the pair of tracks.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This is a continuation of U.S. application Ser. No. 11/251,474, entitled “Thermally driven cooling systems”, filed Oct. 14, 2005, now U.S. Pat. No. 7,437,875. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention is generally related to the area of solar energy systems. In particular, the present invention is related to thermally driven cooling systems based on solar energy, wherein the thermally driven cooling systems can be readily used in solar air conditioning and refrigeration. 
     2. The Background of Related Art 
     Faced with the reality of scarce oil resources, there is a resurgence of interest in solar energy. Compared to the old forms of depletable energy (coal, oil, nuclear), solar energy offers a clean renewable form of energy. Various solar systems have been designed to capture the solar energy and put the energy in different applications. One exemplary solar system is to heat water by solar energy. 
       FIG. 1  shows a prior art solar system  100  that includes a solar batch heater  102 , a solar collector  104 , a first pump  106 , a second pump  108  and a water storage tank  110 . The solar batch heater  102 , commercially available or to be readily made, absorbs solar energy and heats up a water flow going through. The first pump  106  is provided to drive a type of liquid (e.g., antifreeze) through the solar batch heater  102  and subsequently heat water stored in the water storage tank  110 . While cold water may be replenished into the water storage tank  110  as the heated water is pumped out for use by the second pump  108 , the first pump  106  circulates the liquid through the solar batch heater  102  to be heated. The solar collector  102  is provided to generate heat from the solar energy, and can be optionally coupled to a photovolvaic energy collector to provide electricity. Both of the first pump  106  and the second pump  108  may be driven by the power from the photovolvaic energy collector or energized by regular household electricity. 
       FIG. 1  shows a water heating system without using any external electricity and has been proven fairly efficient. In daily life, there are many other appliances that may be powered by solar energy, for example, air conditioning and refrigerators, both are traditionally powered by electricity. The present invention is to provide a cooling system without using any external electricity that may be readily used to power air conditioning and refrigeration entirely using solar energy. 
     SUMMARY OF THE INVENTION 
     This section is for the purpose of summarizing some aspects of the present invention and to briefly introduce some preferred embodiments. Simplifications or omissions in this section as well as in the abstract and the title may be made to avoid obscuring the purpose of this section, the abstract and the title. Such simplifications or omissions are not intended to limit the scope of the present invention. 
     In general, the present invention pertains to designs of cooling systems that may be used in refrigeration and air conditioning. According to one aspect of the present invention, a solar energy collecting device is disposed outdoor to collect solar energy. A first heat-to-electricity generator is an accelerated magnetic piston generator operating on heated liquid (e.g., antifreeze water/refrigerant) provided to produce the electricity. A storage tank is used to store heated water. A first pump device, powered by the accelerated magnetic piston generator, provides the electricity to the pump to circulate the liquid through the storage so that the liquid is gradually heated up when going through the solar energy collecting device. A second heat-to-electricity generator is disposed in the storage water and operates on the heated water to generate electricity. A cooling system operates on at least three types of working fluids to achieve low temperature evaporation and high temperature condensation to derive cooling effects. A working unit powered by at least one of the first generator and the second generator is provided to utilize the cooling effects from the cooling system. As a result, an air conditioner or a refrigerator can be readily implemented, where the air conditioner or refrigerator operates entirely on solar energy. 
     According to another aspect of the present invention, a retractable shield is provided to protect a solar energy collecting device. In general, a solar energy collecting device, some including silicon cells, is very fragile. It is desired to provide some means of protection to the solar energy collecting device. In one embodiment, a retractable shield is controlled by an automatic roller operating in accordance with one or more sensors. When, for example, the wind is too strong or the heat is too intense, the roller operates to have a shield cover partially or entirely the solar energy collecting device. 
     The present invention may be implemented in many ways as a subsystem, a device or a method. According to one embodiment, the present invention is a cooling apparatus that comprises a collecting device disposed outdoor to collect solar energy, a circulating device causing a type of liquid to go through the collecting device in circulation so that the liquid is gradually heated by the collecting device; a storage tank provided to store water to be heated by the heated liquid; a first generator converting heat/pressure in the liquid to electricity; a cooling system operating on at least three types of working fluids that achieve low temperature evaporation and high temperature condensation to derive cooling effects; and a working unit powered by at least the first generator to utilize the cooling effects from the cooling system. 
     One of the objects, features, advantages of the present invention is to provide a cooling mechanism that operates entirely on solar energy. 
     Other objects, features, and advantages of the present invention will become apparent upon examining the following detailed description of an embodiment thereof, taken in conjunction with the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, appended claims, and accompanying drawings where: 
         FIG. 1  shows a prior art solar system that includes a solar batch heater, a solar collector, a first pump, a second pump and a water storage tank; 
         FIG. 2  shows an exemplary design in accordance with one embodiment of the present invention; 
         FIG. 3  shows a functional block diagram of an exemplary cycle thermodynamic model; 
         FIG. 4  shows one embodiment of generating cool air based on the cycle thermodynamic model of  FIG. 3 ; and 
         FIG. 5  shows a side view of an embodiment using a shield that can be retracted along a pair of tracks to cover a solar batch heater. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention pertains to designs of cooling systems that may be used in refrigeration and air conditioning. Such cooling systems operate entirely on solar energy. The detailed description of the present invention is presented largely in terms of procedures, steps, logic blocks, processing, or other symbolic representations that directly or indirectly resemble the operations of optical devices or systems that can be used in optical networks. These descriptions and representations are typically used by those skilled in the art to most effectively convey the substance of their work to others skilled in the art. 
     Reference herein to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the invention. The appearances of the phrase “in one embodiment” in various places in the specification are not necessarily all referring to the same embodiment, nor are separate or alternative embodiments mutually exclusive of other embodiments. 
     Referring now to the drawings, in which like numerals refer to like parts throughout the several views.  FIG. 2  shows an exemplary design  200  in accordance with one embodiment of the present invention. In addition to the solar batch heater  102 , the first pump  106 , the second pump  108  and the water storage tank  110  as described in  FIG. 1 , the design  200  includes a first power generator  202 , and a second power generator  204  and a cooling system  206 . The first power generator  202  is connected to the solar batch heater  102 . With the heated water from the solar batch heater  102 , the first power generator  202  produces electricity. According to one embodiment, the first power generator  202  is an accelerated magnetic piston generator that is known to have the flexibility to be powered by any source of thermal (heat) or pressure energy to produce electricity. The website address “http://peswiki.com/index.php/Directory:Accelerated_Magnetic_Piston_Generator” which is incorporated by reference shows the principle of an exemplary accelerated magnetic piston generator. 
     When solar energy is not available (in the evening), to keep an apparatus (e.g., air conditioning) running supported by the design  200 , a second power generator  204 , located in the water storage tank  110 , and at  207  is provided. The cooling system  206  is provided to generate cooling effects based on what is referred to as a cycle thermodynamic model.  FIG. 3  shows a functional block diagram of an exemplary cycle thermodynamic model  300 . 
     The cycle thermodynamic model  300  includes an evaporator  302 , pre-cooler  304 , a condenser/absorber  306 , a generator  308 , a reservoir  310 , and a bubble pump  312 . According to one embodiment, the evaporator  302  stores partially a type of refrigerant and pressure equalizing gas, both arriving from the pre-cooler  304  in nearly pure form (shown as points  4  and  2 ). As described what is commonly referred to as the Einstein-Szilard pump, the refrigerant evaporates in the presence of the pressure equalizing gas due to a lowering of the partial pressure of the refrigerant. The pressure equalizing gas is close to condensation in the evaporator  302 , the actual process is further described below. 
     First, nearly pure saturated liquid butane flows in from the condenser/absorber  306  at the condenser/absorber temperature (noted as state  2  in  FIG. 3 ). Simultaneously, saturated vapor ammonia (noted as state  4  in  FIG. 3 ) is bubbled into the liquid butane. The presence of the ammonia vapor reduces the partial pressure of the butane causing it to evaporate. As it evaporates into the ammonia vapor, the butane cools itself, the ammonia vapor, and produces external cooling. A small amount of ammonia vapor is also absorbed into the liquid butane producing some heat of absorption which is also removed by the evaporating butane. For a given system pressure, the temperature in the evaporator  302  depends upon the relative butane-ammonia flow rates. To prevent a temperature glide, which increases the evaporator temperature, the design condition is taken to be at the azeotrope. 
     Although the vapor mixture leaving the evaporator  302  at state  3  is not cold enough to provide additional refrigeration, it is cold relative to the fluids coming to the evaporator  302 . The pre-cooler  304  allows the cooling of the two streams entering the evaporator  302  via the heating of the stream leaving the evaporator  302 . The pre-cooler  304  is assumed to operate under steady state conditions with no fluid friction and is insulated so that the only heat transfer occurs between the entering streams and exiting streams. Thus the conservation of mass will be satisfied between the evaporator  302  and condenser/absorber  306 . 
     In the refrigeration cycle, the condenser and absorber are combined into a single component  306  where both processes occur simultaneously as shown in  FIG. 3 . When the vapor mixture leaving the pre-cooler  304  at state point  6  enters the condenser/absorber  306 , it encounters a large surface area created by a falling film of sub-cooled liquid water weak in ammonia. The water film, which enters the condenser/absorber  306  at state  9 , readily absorbs the ammonia from the vapor mixture. This increases the concentration of butane in the vapor and hence the partial pressure on the butane in the vapor. Now the butane can condense at its saturation temperature for this system pressure which is well above the temperature at which it evaporated earlier in the evaporator  302 . 
     The liquid water, now rich in ammonia, and butane descend the walls of the condenser/absorber  306 . Since the ammonia-water solution is immiscible with the butane, and is more dense, it sinks to the bottom of the condenser and flows out at point  7 . The light, immiscible butane floats atop the solution and exits at point  1 . The condenser operates at steady state and the liquids leaving the condenser are assumed to be in thermal and vapor-liquid equilibrium at the temperature of the condenser. 
     In the generator  308 , ammonia rich water arriving from the condenser/absorber  306  is heated. This generates vapor ammonia (shown as state  5  in  FIG. 3 ) which then flows to the evaporator  302 . The remaining water, containing less ammonia, drops to the bottom of the generator where it flows into the bubble pump and is returned to the condenser. Before it is returned to the condenser, this hot ammonia-water solution transfers its heat to the cooler ammonia-water solution arriving from the condenser/absorber  306 . 
     To circulate the working fluids without a mechanical pump, the cycle relies on a bubble pump  312 . A bubble pump is a heated tube (length L and diameter d) communicating with two reservoirs, one higher than the other. The liquid in the lower reservoir  308  initially fills the tube to the same level (h). Heat is applied at the bottom of the tube at a rate sufficient to evaporate some of the liquid in the tube. The resulting vapor bubbles rise in the tube carrying the liquid above them to the higher reservoir. The bulk density of the fluid in the tube is reduced relative to the liquid in the lower reservoir, thereby creating an overall buoyancy lift. 
     It is known in the art that there are four flow regimes for two-phase up flow in a fixed diameter vertical pipe. For low vapor flow rates, small, finely dispersed vapor bubbles will rise in a continuous liquid phase. This is the bubble flow regime. Increasing the vapor flow causes the vapor bubbles to coalesce into bullet shaped slugs of vapor which rise in the liquid phase. This is the slug flow regime, and a bubble pump operates most efficiently here. Further increase of vapor flow causes a highly oscillatory flow with a tendency for each phase alternatively to fill the tube. This is the churn flow regime. The last flow regime, reached by even further increase of vapor flow, is the annular flow regime in which the liquid forms a film around the pipe wall and the vapor rises up the core. For further information about the operation of the cycle thermodynamic model  300 , the website address “http://www.me.gatech.edu/energy/andy_phd/three.htm”, which is hereby incorporated by reference, has a detailed description together with all necessary theory to support the operation. 
     Referring now to  FIG. 4 , there shows one embodiment of generating cool air based on the cycle thermodynamic model  300  of  FIG. 3 . Air (assuming hot air) comes at an opening  402 . A thermionic generator  404  is essentially a heat-to-electrical generator provided to energize an air transporter  406 . In one embodiment, the air transporter  406  is an electro-kinetic air transporter and conditioner. An exemplary electro-kinetic air transporter and conditioner is detailed in U.S. Pat. No. 6,911,186 which is hereby incorporated by reference. The air transporter  406  creates an air flow that pass through an optional refrigerant coil being cooled by the cycle thermodynamic design  300  of  FIG. 3 . The cooled air exits from an air ventilation opening  408 . As a result, an air conditioning system is created and operates entirely on solar energy. 
     According to one embodiment of the present invention, an array of vacuum solar tubes are used to collect the heat (solar energy), the heated water/refrigerant is stored into the hot water in one or more water tanks. The heat source in the water tanks is supplied to a single pressure direct thermally driven cycles system that requires no electricity because a complete cycle operates under single pressure. Using the gravity as a pump, this single pressure eliminates the need for a mechanical/electrical pump. 
     These cycles need to use at least three types of working fluids that achieve low temperature evaporation and high temperature condensation by utilizing the partial pressure of the refrigerant for the benefits of complete silent operation and cost effective solution. In addition, the cooling devices (e.g., a refrigerator or an air conditioner) contemplated in accordance with the present invention include no moving parts and provide high reliability and portability in overall performances. 
     According to one embodiment, a combination of water and antifreeze is used for solar energy collection (e.g., solar batch heater and solar heat recovery and storage) while a combination of iso-butane, ammonia and water are used for the single pressure system (e.g., the cycle thermodynamic model) that deliver the cooling effects. A thermionic generator (e.g., triode designs) is used to convert heat into ions that can be used to create an air flow from an air inlet to an air outlet, for the ventilation system or by the usage of an accelerated magnetic piston generator inside a water heated tank or/and inside the single pressure mechanism to generate electricity (from heat, or pressure) that permit to use the ionic generator for creating the airflow. 
     The energy necessary to run a negative air ionizer (e.g., an electro-kinetic air transporter and conditioner) come from an accelerated magnetic piston generator inside the hot water tank and/or inside the single pressure mechanism or both of them at the same time. In one embodiment, the energy comes form a generator in the hot water tank, where the generator includes two dissimilar metal wires and the temperature difference between the junction of the two dissimilar metal wires produces a voltage potential (known as the Seebeck effect), US Patent Publication 20030066476, which is hereby incorporated by reference, has a detailed description of such operation. The electricity can now energize the air ionizer, and in addition to the single pressure system that generates cold to generate air conditioning. 
     To protect the vacuum solar tubes,  FIG. 5  shows a side view of an embodiment  500  using a shield  502  that can be retracted along a pair of tracks  504 . The operation of the shield  502  is controlled by a motor that is in return controlled by one or more sensors. Examples of the sensors may include temperature sensor or wind velocity sensor. In general, the vacuum solar tubes or a solar energy collecting device is disposed outdoor. When the liquid going through the vacuum solar tubes is heated beyond a predefined temperature (e.g., via a temperature sensor), the shield may be in partially or fully closed position so as to reduce or stop the solar energy absorption. Likewise, when wind speed exceeds a predefined velocity (via a wind velocity sensor), the shield may be in fully closed position to protect the vacuum solar tubes from being damaged by the wind. According to one embodiment, the motor, an auxiliary circuit, possible the sensors are powered by one of the first power generator  202  and the second power generator  204  or batteries. 
     While the present invention has been described with reference to specific embodiments, the description is illustrative of the invention and is not to be construed as limiting the invention. Various modifications to the present invention can be made to the preferred embodiments by those skilled in the art without departing from the true spirit and scope of the invention as defined by the appended claim. Accordingly, the scope of the present invention is defined by the appended claims rather than the forgoing description of embodiments.