SOLAR POOL HEATER

An automated wirelessly-controlled solar pool heater including a photothermal module atop a floatation vessel for exposure to the sun, an internal pump assembly, a first temperature sensor for sensing temperature in the photothermal module, a second temperature sensor for sensing ambient pool water, a microcontroller board with wireless transceiver for remote monitoring and operation, and a solar-charging battery. In operation, the pump assembly self-primes and automatically fills the entire photothermal module with pool water. Water in the photothermal module begins to heat via heat absorption from the sun's rays and, when heated, the microcontroller activates the pump assembly to intermittently expel a partial volume of the heated water back into the pool, simultaneously refilling the photothermal module with unheated pool water. The recirculation program continues until the water temperature of the entire pool reaches its desired temperature.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to pool heaters and, in particular, a floating solar pool heater that employs a passive photothermal module for solar heat absorption and a wireless-enabled processor for remote pool temperature control.

2. Description of the Background

Water heaters are often used in pools to maintain a comfortable water temperature. There are a variety of different types of pool water heaters. For example, flexible covers made of heat-absorbing materials are used to raise the temperature of the pool water. Unfortunately, pool covers restrict access to the water, are unwieldy and cumbersome to remove and replace, difficult to store, and often sink below the surface of the water.

Electrically-operated heaters are effective in some circumstances, but are expensive to operate and potentially unsafe if electrical contacts are exposed to the water.

Gas-operated heaters are also effective in some circumstances, but are likewise expensive to operate and potentially unsafe if the gas leaks.

Solar pool heaters are well-known and solve the foregoing problems. Solar heaters typically feed water to stationary solar panels installed nearby. The pool water may be pumped to the solar panels via electric pumps. However, most conventional solar pool heaters are very expensive, large and aesthetically unpleasant, and require substantial effort to install. They are also fairly inefficient due to heat loss in the return lines.

Consequently, there remains a need for a low cost modular high efficiency solar pool heater that can alleviate the disadvantages of the existing solar pool heating systems.

What is needed is a compact and efficient fully-automated and yet remotely controlled solar pool heater.

SUMMARY OF THE INVENTION

According to an embodiment of the invention, an automated wirelessly-controlled solar pool heater is disclosed that includes a photothermal module arrayed on a floatation vessel for good exposure to the sun, a pump assembly for intermittently pumping water through the photothermal module, one or more temperature sensors for sensing temperature in the photothermal module. The water is pumped by a pump assembly powered by a battery bank that is charged by a solar panel. The pool heater is controlled by a microcontroller board with wireless transceiver for remote monitoring and programmed operation. In operation, the pump assembly self-primes and automatically fills the entire photothermal module with pool water. Water in the photothermal module begins to heat via heat absorption from the sun's rays. Initially it takes 9-10 minutes for the water in photothermal module to reach a maximum temperature, at which point the microcontroller board activates the pump assembly to intermittently expel a partial volume of the heated water residing therein back into the pool, simultaneously refilling the photothermal module with unheated pool water. The recirculation program continues until the water temperature of the entire pool reaches its desired temperature.

The present invention is described in greater detail in the detailed description of the invention, and the appended drawings. Additional features and advantages of the invention will be set forth in the description that follows, will be apparent from the description, or may be learned by using the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

As seen inFIG.1, the present invention is an automated wirelessly-controlled solar pool heater2comprising a floatation vessel10, a passive water-heating photothermal module20arrayed in a circuitous pattern for good surface area exposure to the sun, and an internal computer-controlled solar-powered pump assembly (to be described) for periodically inducting pool water into the photothermal module20for heating and expelling heated water from photothermal module20back into the pool.

FIG.2is a bottom view of the solar pool heater2,FIG.3is a side view, andFIG.4is a side cross-section taken along the line A-A ofFIG.3. With combined reference toFIGS.2-4the floatation vessel10comprises a disc-shaped housing with enclosed buoyancy ring12surrounding a central chamber14that is subdivided into separate water-proof compartments for the pump assembly30and micro-controller board70, plus a downwardly-protruding compartment13with pull-down spout44that when deployed protrudes well-beneath the water level for extended water intake and outlet.

The photothermal module20is carried atop the floatation vessel10for maximum sun absorption. In the illustrated embodiment the photothermal module20defines a circuitous interior matrix or array of dark-colored conduits22that maximize surface contact with the water therein for maximum photothermal efficiency.

FIG.2illustrates the spout44, which is a square open-ended tubular member formed with hinge pins45at one end journalled into the walls of the bay13. The spout44may be seated flush inside bay13or deployed to a downwardly extended position protruding3-6″ beneath bay13. Detent clips46may be provided to prevent inadvertent deployment. The water intake tube23and discharge tube35both enter the spout44at the hinged end.FIG.2also illustrates two opposing handles49molded into the bottom of the floatation vessel10to assist in carrying the solar pool heater2.

With spout44extended, the pump30intermittently pumps water into the circuitous photothermal module20through intake tube23, where it travels through the circuitous path past one of at least two temperature sensors40,42(one internal sensor40for sensing temperature in the photothermal module20and one external sensor42for the temperature of the pool water). A battery bank50is connected to the pump30, to a solar panel60for maintaining battery bank50charge, and to a microcontroller board70with processor, software and wireless transceiver for remote monitoring and programmed operation of solar pool heater2as will be described. In operation, when first placed in the pool the pump assembly30is self-priming and automatically fills the entire photothermal module20. Once full, the pump assembly30stops and the water in the photothermal module20begins to heat via heat transfer from the black photothermal module absorbing the sun's rays. The darkly-colored (e.g., black) circuitous interior conduits22of photothermal module20absorb the sun's heat and transfer it to the water contained inside by direct photothermal contact. Initially it takes 9-10 minutes for the water in photothermal module20to reach a maximum temperature (e.g., 115 degrees). Microcontroller board70monitors the internal temperature via internal temperature sensor40, which is imbedded inside the photothermal module20, optimally at or near the circuitous midpoint. Once the temperature of the water in the photothermal module20is heated to a preset temperature apex, microcontroller board70activates the pump assembly30to expel a volume of the heated water residing in photothermal module20(e.g., half the water) back into the pool, simultaneously refilling half the photothermal module20with unheated pool water. Water remaining in the photothermal module20mixes with the incoming pool water and heats it, allowing the temperature of the preset water in the photothermal module20to reach its apex more quickly. The recirculation program continues: each time the water in the photothermal module20reaches the preset apex the pump assembly30will again flush a partial volume of the water, and the cycle continues. Microcontroller board70monitors the external temperature via external temperature sensor42, which is outwardly exposed/embedded in the wall of the floatation vessel10, and microcontroller board70continues to periodically recirculate half the water in photothermal module20until the water temperature of the pool water as measured at external sensor42reaches its desired temperature. The microcontroller board70is wirelessly enabled and remotely-programmable by a software application resident on a laptop, smart phone or the like. In the illustrated embodiment the photothermal module20comprises a disc-shaped two-part housing24that is affixed atop buoyancy ring12likewise surrounding central chamber14, e.g., concentric circular discs, for example, of 28″ diameter. Housing24may comprise a black matte bottom section25and top section26that absorbs light energy from sunlight allowing it to heat water contained therein. The bottom section25and top section26of housing24preferably snap-fit together to define a tubiform helical interior passage, or other circuitous interior matrix or array of dark-colored conduits22. One skilled in the art should understand that the bottom section25of photothermal module20may be co-molded with floatation vessel10, and that conduits22need not be molded but may alternatively comprises a separate coiled-hose fitted into a two-part housing24. Although the illustrated photothermal module20is arrayed in a spiral pattern, one skilled in the art should understand that photothermal module20may be continuously-arrayed in most any internal geometric pattern, e.g., square, hexagon, etc., affixed atop a conforming floatation vessel10. Photothermal module20leaves room at the center for the central chamber14of floatation vessel10, which again is preferably subdivided into separate water-proof housings for the bay13, pump assembly30, battery bank50, and microcontroller board70. The pump assembly30includes a pump, preferably a 12V solar water pump such as, for example, a Kamoer™ KLP02 micro diaphragm pump with 12V DC brushless motor and 700 ml/min flow rate. The output of pump30is preferably connected via port31to one end of the internal conduit of photothermal module20by a clear intake tube32for easy viewing. Similarly, the other end of the internal conduit of photothermal module20is connected via discharge port21through a clear tube35. Both tubes32,35continue into spout44, which extends water intake/discharge below the floating waterline of floatation vessel10.

The solar panel60is a small circular 7″ panel adhered atop a conical riser62that fits atop the central chamber14of floating housing10, preferably using a quarter-turn twist-lock engagement to provide easy access to the battery50. The solar panel60is calibrated to charge the battery bank50, hence the solar panel60may output 700 mA at 12V to charge a battery bank50comprising a 12V 8Ah NiMH Rechargeable Battery. The battery bank50provides power to the pump30through a first fuse block72and to microcontroller board70via a second fuse block72.FIG.5is a block diagram of the pump assembly30, temperature sensor40, temperature sensor42, battery bank50, solar cell60and microcontroller board70. The microcontroller board70includes a processor72, on board non-transitory memory74, and an on- board wireless transceiver76for remote communication. Processor72is in communication with temperature sensors40,42. As indicated above the temperature sensor40is imbedded inside the photothermal module20at or near the midpoint to provide a temperature measurement of the water inside the photothermal module20to processor72. In contrast, temperature sensor42is preferably embedded in the bottom wall of bay13. This way, processor72can also monitor the temperature of the pool water. Processor board70may be any suitable low-power computer processor platform with on-board memory74and wireless communication capability by, for example, LAN and/or Bluetooth® connectivity via transceiver76. A software application is stored in memory74for execution by processor72.

FIG.6is a schematic diagram of an exemplary solar charging module for maintaining battery bank50via solar panel60, which is based on a Texas Instrument™ BQ25172 integrated 800-mA linear charger for 1-cell to 6-cell NiMH batteries.

FIG.7is a schematic diagram of an exemplary microcontroller board70which is based on an ST™ STM32WB5MMG wireless microcontroller incorporating an Arm® Cortex®-M4 processor core72running at 64 MHz (application processor) and an Arm Cortex-M0+ wireless core76(wireless front end), with onboard 1 Mbyte Flash memory74and capable of wireless Bluetooth LE 5.4 and 802.15.4 protocols.

The internal temperature sensor40and external temperature sensor42may be any suitable temperature sensors capable of accurately sensing a range of from 55° C.˜130° C. , such as Texas Instruments™ LM19CIZ/LFT4.

FIG.8is a flow diagram of the resident software application stored in memory74.

At step110the solar pool heater2is powered up and the software instantiates. The software requires several programmed parameter settings all of which initiate to default settings but may be user-customized by wireless transmission from a remote application running on a user's smartphone or other remote device.

At step115the processor72waits three times the Dwell Time to allow the user to place the solar pool heater2in their pool.

At step120the processor72measures and compares the battery bank50voltage to the Low Volt Cut-Off to ensure that the battery bank50has an operational charge. If not, at step125a battery error LED flashes. If the battery bank50voltage is greater than the Low Volt Cut-Off, then processor72activates the pump assembly30for a multiple of Pump-time Durations sufficient to prime and automatically fill the entire photothermal module20, e.g., four times a Pump-time Duration equals 32 seconds.

At step130, the processor72then waits a predetermined delay period, some multiple of the Dwell Time (e.g., five times the Dwell Time or 10 minutes) for the water in photothermal module20to warm fully. The initial delay period is calibrated to ensure that the water in photothermal module20reaches its apex temperature, typically resulting in a temperature differential of fifteen degrees between the pool water temperature versus the water temperature in the photothermal module20. Use of an apex temperature differential maximizes the heating advantage of the photothermal module20and minimizes the amount of time needed to raise the pool water temperature.

At step135the processor72measures the apex temperature of the water in photothermal module20Ta at sensor40and stores the measured apex Ta. Processor72the compares the temperature of the water in photothermal module20Ta at sensor40to the pool water temperature Tp, and so long as Ta>Tp proceeds to step140.

At step140the processor72again measures and compares the battery bank50voltage to the Low Volt Cut-Off to ensure that the battery bank50has an operational charge. If not, flow returns to step115to await a full charge. If so, processor72activates the pump assembly30for a single Pump-time Duration sufficient to refresh one-half the water in photothermal module20, e.g., one times a Pump-time Duration equals 8 seconds.

Flow proceeds to step145and processor72then waits a predetermined delay period, e.g., a single Dwell Time (2 minutes) for the new water inducted into photothermal module20to warm fully.

Next, at step150, the processor72measures the apex temperature of the water in photothermal module20Ta at sensor40and stores the measured apex Ta, and the pool water temperature Tp at sensor42. Processor72the compares the temperature of the water in photothermal module20Ta at sensor40to the pool water temperature Tp, and if Ta>Tp AND the pool water temperature Tp is less than the desired pool temperature Max Temp (115 F), flow proceeds to step175.

At step175processor72activates the pump assembly30for a single Pump-time Duration sufficient to refresh one-half the water in photothermal module20, e.g., one times a Pump-time Duration equals 8 seconds.

At step180processor72resets a cycle count and returns to step145.

If at step150processor72compares the temperature of the water in photothermal module20Ta at sensor40to the pool water temperature Tp, and either Ta<Tp OR the pool water temperature Tp equals or exceeds the desired pool temperature Max Temp (115 F), flow proceeds to step155.

At step155processor72increments the cycle count.

At step160processor72compares the current cycle count to the Count Limit (e.g., 5 sec). If the current cycle count is less than or equal to the Count Limit flow proceeds to step145. If the current cycle count exceeds the Count Limit flow returns to step130above. The recirculation steps145,150,175and180repeat as needed, flushing a partial volume of the water, until the water temperature of the entire pool reaches the desired preset maximum temperature Max Temp.