Abstract:
A solar-thermal powered recreational vehicle featuring a solar-thermal air conditioning system integrated with a solar clean energy system to provide a recreational vehicle having improved energy efficiency. In an embodiment employing the principles of the present invention, the solar-thermal powered recreational vehicle can comprise a clean energy system for providing electrical power to the recreational vehicle, whereby the clean energy system features one or more solar photovoltaic panels, a batter bank, and a generator operatively coupled to a hybrid inverter. The solar-thermal air conditioning system is powered by the clean energy system, with the solar-thermal air conditioning system featuring a solar-thermal collector panel functioning to superheat compressed refrigerant prior to the compressed refrigerant being transmitted to the condenser. Because the compressor is the most energy-intensive component in the traditional direct expansion AC system, the use of free solar energy by the present invention to reduce the work load on the compressor significantly reduces the overall energy requirements of the recreational vehicle, thereby providing a recreational vehicle capable of operating on solar and battery power alone for significant periods of time.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a continuation of U.S. application Ser. No. 14/737,339, filed Jun. 11, 2015, which claims the benefit of U.S. Provisional Application No. U.S. 62/139,517, filed Mar. 27, 2015 and U.S. Provisional Application No. U.S. 62/011,443, filed Jun. 12, 2014, all of which are hereby incorporated by reference. 
     
    
     BACKGROUND 
       [0002]    Recreational vehicles (RVs) are vehicles designed as temporary living quarters for recreational, camping, travel or season use. Two main categories of RVs exist: motorized motorhomes and towable trailers, which can be towed behind a vehicle. Motorized motorhomes typically are broken into classes, with Type A motorhomes being the largest, Type B motorhomes or van campers being the smallest, and Type C motorhomes generally falling in between. Types of towable RVs include folding camping trailers, expandable trailers, truck campers, conventional travel trailers and fifth-wheel travel trailers. 
         [0003]    RVs offer a convenient, hassle-free way to travel. RVs have been shown to allow its owners to be more physically active than on typical vacations, and traveling by RV can provide reduced exposure to illness and other health risks. However, the environmental friendliness of RVs increasingly is a concern for RV owners, potential owners, and users alike. The environmental impact of RVs extends beyond just the fuel economy of the motorhomes or the vehicles pulling towable RVs. With fully-equipped kitchens and baths, flat-screen TVs, surround-sound stereos and more, the living quarters of today&#39;s RVs consume a substantial amount of energy in their own right. The HVAC systems utilized in RVs impose a particularly large energy load. Traditional RV HVAC systems are self-contained, roof mounted units which typically operate at 115 Volts AC power. These units are renowned for being energy inefficient, thereby requiring the operation of a generator to meet the power demands of the HVAC system. 
         [0004]    Attempts to incorporate solar electric systems into RVs have been made. However, because of the high electrical load and limited surface area on which to mount PV arrays, solar power has not been considered a viable option for meeting the RV&#39;s complete energy needs. Rather, solar power has only been considered suitable for small loads, such as lights, small TV&#39;s, computers, and other small appliances. For heavy loads such as the HVAC system, a generator is required. 
       SUMMARY OF THE INVENTION 
       [0005]    The recreational vehicle of the present invention features an energy efficient solar-thermal air conditioning system which utilizes a solar collector to superheat the working fluid, thereby reducing the work load imparted on the compressor. Because the compressor is the most energy-intensive component in the traditional direct expansion AC system, the use of free solar energy to reduce the work load on the compressor significantly reduces the overall energy requirements of the HVAC system. Whereas traditional recreational vehicles typically use anywhere from 4-8 kWh under normal operating conditions, the recreational vehicle of the present invention utilizes approximately 0.7-3.0 kWh under the same conditions. This reduction in the electrical load allows the recreational vehicle to operate on solar and battery power alone for significant periods of time, thereby reducing fossil fuel consumption and the decibel level within the vehicle caused by repeated and prolonged generator cycles. The reduction of generator cycles reduces also diminishes the threat of carbon monoxide exposure to occupants of the recreational vehicle. 
         [0006]    The invention disclosed herein is directed to a solar-thermal powered recreational vehicle featuring a solar-thermal air conditioning system integrated with a solar clean energy system to provide a recreational vehicle having improved energy efficiency. In an embodiment employing the principles of the present invention, the solar-thermal powered recreational vehicle can comprise a clean energy system for providing electrical power to the recreational vehicle. The clean energy system can feature one or more solar photovoltaic panels mounted to the top of the body or enclosure of the recreational vehicle and operatively coupled to a hybrid inverter. The clean energy system can also feature both a battery bank and a generator. In instances where excess solar energy is collected by the solar photovoltaic panels, the excess electrical power will be routed by a charge controller to the battery bank for storage. The stored energy in the battery bank can routed by the hybrid inventor to the recreational vehicle to supplement or replace the solar power if the solar energy collected by the solar photovoltaic panels is insufficient to meet the current power load of the recreational vehicle. Likewise, if the solar panels and battery bank are unable to meet the power load of the recreational vehicle, a generator switch will automatically activate and engage the generator. Power from the generator will then be routed by the hybrid inventor to the recreational vehicle to meet its power needs. 
         [0007]    The solar-thermal powered recreational vehicle can also feature a solar-thermal air conditioning system powered by the clean energy system. The solar-thermal air conditioning system can feature a condenser unit comprising a compressor and a condenser. A solar-thermal collector panel can be operatively connected to the compressor and condenser. The solar-thermal collector panel will heat the compressed refrigerant prior to the compressed refrigerant being transmitted to the condenser. An air handling unit can be mounted to the enclosure for providing the conditioned air to the enclosure. The air handling unit can feature an evaporator coil and a fan. The evaporator coil will be operatively connected to the condenser such that the refrigerant can be routed from the condenser, to the evaporator, and back to the solar compressor. 
         [0008]    The above summary is not intended to describe each illustrated embodiment or every possible implementation. 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. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0009]    The accompanying figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views, and which, together with the detailed description below, are incorporated in and form part of the specification, serve to illustrate further various embodiments and to explain various principles and advantages in accordance with the present invention: 
           [0010]      FIG. 1  is a diagram showing the interconnectivity of the solar-thermal air conditioning system and clean energy system for use in a solar-thermal powered recreational vehicle embodying principles of the present invention. 
           [0011]      FIG. 2  is another diagram showing the interconnectivity of the solar-thermal air conditioning system, clean energy system, and various electronic components for use in a solar-thermal powered recreational vehicle embodying principles of the present invention. 
           [0012]      FIG. 3  is a perspective view of a solar-thermal powered recreational vehicle embodying principles of the present invention. 
           [0013]      FIG. 4  is a side view of the of a solar-thermal powered recreational vehicle depicted in  FIG. 3 . 
           [0014]      FIG. 5  is a detailed section view of the storage area identified in  FIG. 4 , showing several of the internal components of the solar-thermal powered recreational vehicle depicted in  FIGS. 3 and 4 . 
           [0015]      FIG. 6  is a perspective view of another embodiment of a solar-thermal powered recreational vehicle embodying principles of the present invention. 
           [0016]      FIG. 7  is a side view of the of a solar-thermal powered recreational vehicle depicted in  FIG. 6 . 
           [0017]      FIG. 8  is a detailed view of the storage area of the of a solar-thermal powered recreational vehicle depicted in  FIG. 6  showing several of the internal components. 
           [0018]      FIG. 9  is a perspective view of another embodiment of a solar-thermal powered recreational vehicle embodying principles of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]    A solar-thermal powered recreational vehicle featuring a solar-thermal air conditioning system integrated with a clean energy system is described herein. The description which follows, and the embodiments described therein, is provided by way of illustration of examples of particular embodiments of principles and aspects of the present invention. These examples are provided for the purposes of explanation—and not of limitation—of those principles of the invention. In the description that follows, like parts are marked throughout the specification and the drawings with the same respective reference numerals. As used herein, the term “about” or “approximately” applies to all numeric values, whether or not explicitly indicated. These terms generally refer to a range of numbers that one of skill in the art would consider equivalent to the recited values (i.e., having the same function or result). In many instances these terms may include numbers that are rounded to the nearest significant figure. Relational terms such as first and second, top and bottom, right and left, and the like may be used solely to distinguish one component or feature from another component or feature without necessarily requiring or implying any actual such relationship or order between such components and features. 
         [0020]    Referring to  FIGS. 1-2 , the solar-thermal powered recreational vehicle can comprise a clean energy system  100  for providing electrical power to the recreational vehicle  1 . The recreational vehicle  1  has an enclosure having a front wall, a rear wall, a roof, a floor, and two opposing side walls. The clean energy system  100  can feature one or more solar photovoltaic panels  110  mounted to the roof of the recreational vehicle and operatively coupled to a hybrid inverter  150 . The clean energy system can also feature both a battery bank  130  and a generator  140 . In instances where excess solar energy is collected by the solar photovoltaic panels  110 , the excess electrical power will be routed by a charge controller  120  to the battery bank  130  for storage. The stored energy in the battery bank  130  can routed by the hybrid inventor  150  to the recreational vehicle to supplement or replace the solar power if the solar energy collected by the solar photovoltaic panels  110  is insufficient to meet the current power load of the recreational vehicle. Likewise, if the solar panels  110  and battery bank  130  are unable to meet the power load of the recreational vehicle, a generator switch  141  will automatically activate and engage the generator  140 . Power from the generator  140  will then be routed by the hybrid inventor  150  to the recreational vehicle to meet its power needs. Lastly, should shore power  109  be available, power will be routed through by the hybrid inventor  150  to the recreational vehicle  1 . Thus, power can be supplied by the hybrid inverter  150  from four different energy sources: shore power  109 , the solar photovoltaic panels  110 , the battery bank  130 , or the generator  140 . Regardless of the power source, the hybrid inventor  150  will distribute  110  volt electricity to the recreational vehicle  1  to meet its power needs, such as appliances, lights, electronics, and the solar-thermal air conditioning system discussed below. 
         [0021]    Still referring to  FIGS. 1-2 , the solar-thermal powered recreational vehicle  1  also features a solar-thermal air conditioning system powered by the clean energy system. The solar-thermal air conditioning system includes a compressor  231 , a solar collector  210 , a condenser  232 , a metering device  240 , and an evaporator  220 .  110  volt power can be distributed directly to the condenser  232 , evaporator  220 , and metering device  240  (if required) by the hybrid inverter  150 . However, in order to power the HVAC compressor, an auto transformer  160  (i.e., a 110-220 up/down voltage converter) is utilized in order to up-convert power leaving the hybrid invertor  150  from 110 volts to 220 volts. 
         [0022]    In operation, refrigerant/working fluid can be routed sequentially through the compressor  231 , the solar-thermal collector panel  210 , the condenser  232 , the metering device  240 , the evaporator  220 , and then back to the compressor  231 . The compressor  231  mechanically compresses the refrigerant, the solar collector  210  superheats the compressed refrigerant using radiant energy from the sun, the condenser  232  condenses the heated refrigerant, and the evaporator  220  evaporates the condensed refrigerant. By superheating the refrigerant with the aid of the solar collector  210 , the temperature difference between the condenser coil and the ambient air temperature can be increased using free energy (i.e., the solar energy captured by the solar collector). By creating this difference, the air flowing through the condenser  232  will be very cold relative to the temperature of the discharge vapor, allowing the heat energy in the vapor to move into that relatively cold air and cause the refrigerant to condense. Meanwhile, because the load of heating the refrigerant is shared between the solar compressor and the solar collector, the work done by the compressor  231  can be reduced, thereby reducing the power consumption of the compressor  231 . 
         [0023]    The solar photovoltaic (PV) panels  110  can be mounted to the top or roof of the recreational vehicle  1  with standard brackets to supply usable solar power. Preferably, the PV panels  110  are mounted in pairs to allow for the panels to be wired in either parallel configuration or series configuration. In a preferred embodiment, modern six to eight standard 250 watt panels can be mounted to the top of the recreational vehicle  1  and wired in parallel to provide a solar panel array capable of producing approximately 3 kilowatt-hours (kWh). 
         [0024]    The hybrid inverter  150  functions to change the electrical current supplied by the PV array from DC current to AC current. The hybrid inverter  150  preferably is a pure sine wave inverter in modular form. The hybrid inverter  150  can be integrated into a pre-wired panel system capable of receiving power from multiple sources (e.g., a PV array, battery bank, generator, and/or shore power) and distributing it to multiple AC loads. In addition to the hybrid inverter/charger  150 , the integrated panel system preferably comprises AC and DC wiring boxes; a surge protector; a system display and controller; a system communications manager that communicates stacking, load share and power save on/off signals; battery and PV array breakers, a PV GFDI breaker, an input-output-bypass assembly; and additional AC breakers. Commercially available integrated inverter/charger panel systems suitable for use with the present invention include the FLEXpower™ ONE system manufactured by Outback Power, Inc. and the Conext XW™ system manufactured by Schneider Electric SE. 
         [0025]    The battery bank  130  stores excess solar energy collected by the solar PV panels  110 . The battery bank  130  preferably comprises batteries having a large capacity and small footprint. In an embodiment suitable for the present invention, the battery bank  130  be comprises four to six marine batteries. The batteries can be wired in parallel or in series. In a preferred embodiment, the batteries of the battery bank  130  are wired in series to double the voltage from 12 volts to 24 volts. 
         [0026]    The charge controller  120  functions to optimize the PV array&#39;s output which can fluctuate based on shading and temperature variables, as well as regulate discharge from the battery bank  130 . The charge controller  120  can be a stand-alone component, or it may be a module of the integrated inverter/charger panel system. The charge controller settings may be modified to optimize battery life, maximize clean energy operation, or to balance battery life with clean energy operation. In a preferred embodiment, the charge controller is set to limit discharge to 40% of battery capacity. 
         [0027]    The generator  140  functions as a back-up power source when the solar panels  110  and the battery bank  130  are unable to meet the power load of the recreational vehicle  1  and shore power is unavailable. The generator  140  preferably is a 6.5 kW to 8 kW diesel generator prewired for both 110 voltage and 220 voltage. The generator switch  141  will automatically activate or stop the generator  140  in response to changing power requirements. For example, when output power demands exceed the power available from the solar panels  110  and the battery bank  130 , power from the generator  140  will be routed by the hybrid inventor  150  to the recreational vehicle to meet its power needs. 
         [0028]    The solar-thermal air conditioning system of the present invention features a solar collector  210  combined with a direct expansion air conditioning (DX) system (e.g., a compressor  231 , a condenser  232 , a metering device  240 , and an evaporator  220 ). The solar-thermal air conditioning system preferably is a mini-split (ductless) heat pump system, such as the SolarCool™ solar-thermal HVAC system manufactured by Sedna Aire USA and described in U.S. Pat. No. 8,448,458, which is incorporated by reference herein. The solar-thermal air conditioning system comprises a roof-mounted, 20-tube solar collector  210 , an outdoor condenser unit  230  which contains a multi-stage compressor  231  and condenser  232 , and one or more indoor ceiling cassettes which each contain the evaporator coil  220  and a fan. The solar collector  210  and DX system components are interconnected by refrigerant lines to provide a closed refrigerant loop through which the working fluid can be transmitted. 
         [0029]    Referring now to  FIGS. 3-5 , a 5 th  wheel recreational vehicle embodying the principles of the present invention is shown. The recreational vehicle  1  comprises an enclosure having a floor, a roof, and walls. Mounted to the roof of the recreational vehicle  1  are four solar PV panels  110 , a 20-tube solar collector  210 , and ceiling cassettes  220   a ,  220   b ,  220   c  each containing an evaporator coil  220  and a fan. Located beneath the living quarters of the recreational vehicle  1  is the inverter/charger  150 , charge controller  120 , battery bank  130 , generator  140 , condenser unit  230  (compressor  231  and condenser coil  232 ), and the auto transformer  160  (not shown). 
         [0030]    Referring now to  FIGS. 6-8 , a conventional towable recreational vehicle embodying the principles of the present invention is shown. The recreational vehicle  1  comprises an enclosure having a floor, a roof, and walls. Mounted to the roof of the recreational vehicle  1  are six solar PV panels  110 , a 20-tube solar collector  210 , and ceiling cassettes  220   a ,  220   b  each containing an evaporator coil  220  and a fan. As depicted in  FIG. 8 , the generator  140 , inverter/charger  150 , and auto transformer  160  are located in side storage compartments of the recreational vehicle. The condenser unit  230  and the battery bank  130  are suspended beneath the trailer on trays proximate to the axle housings of the trailer. 
         [0031]    Referring now to  FIG. 9 , a Class A motorhome embodying the principles of the present invention is shown. The recreational vehicle  1  comprises an enclosure having a floor, a roof, and walls. Mounted to the roof of the recreational vehicle  1  are four solar PV panels  110 , a 20-tube solar collector  210 , and ceiling cassettes  220   a ,  220   b ,  220   c  each containing an evaporator coil  220  and a fan. As with the 5 th  wheel trailer depicted in  FIGS. 3-5 , the inverter/charger  150 , charge controller  120 , battery bank  130 , generator  140 , condenser unit  230  (compressor  231  and condenser coil  232 ), and the auto transformer  160  (not shown) are located beneath the living quarters of the recreational vehicle  1 . 
         [0032]    Many modifications and other embodiments of the invention set forth herein will come to mind to one skilled in the art having the benefit of the teaching presented in the foregoing description and associated drawings. Therefore, it is to be understood that the inventions are not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.