Patent Application
20240390815
The present disclosure relates to a photovoltaic cell used to provide power to a distillation apparatus.
The present disclosure relates to a photovoltaic cell used to provide power to a distillation apparatus.
The need for clean drinking water is increasingly an issue as the global population increases. Many areas that lack fresh water suitable for use as drinking water have ready access to salt water, gray water, or other contaminated water sources. However, many such areas lack the infrastructure or financial resources to refine water obtained from such sources to a drinkable quality. Frequently, such areas have abundant sunlight. This unique combination has prompted the development of many solar-powered desalination systems to produce drinkable water.
Large scale photovoltaic desalination systems utilize the power generated from photovoltaic cells to boil water or to power other types of water purification systems. These systems require large up-front capital investment and operation of sophisticated technologies. Many remote communities across the globe lack sufficient resources to install and operate such systems.
Small scale or personal-sized solar-powered desalination systems attempt to focus sunlight into a small evaporation chamber. These devices use air as a medium to condense water vapor. Such systems function best under direct sunlight without inhibition by clouds, as these conditions are most suitable for evaporation of water. However, because the air is at a higher temperature, these conditions are least conducive to condensing water vapor. Thus, such systems are often highly inefficient or otherwise not very effective.
U.S. Patent Application Publication No. 2016/0114259 to Muller, et al. discloses a solar-powered desalination system that uses a heating unit to further heat the impure water to be purified. U.S. Pat. No. 9,834,455 to Frolov, et al. discloses a solar-powered desalination system that uses a heat exchanger to extract residual heat from the purified water that is then used to further heat the impure water to be purified. These and other disclosed solar-powered desalination systems that may be suitable for use in some small scale or personal-sized applications are encumbered by complexity, and thus such systems may not necessarily be suitable for inexpensive mass production for use in resource-poor or remote areas.
There remains a significant need for a simple, effective small scale or personal-sized solar-powered desalination system.
The present disclosure describes an apparatus that may be used to generate desalinated water from a supply of untreated water using a photovoltaic cell. The front surface of the photovoltaic cell is adjacent to the bottom of an evaporation chamber. The top and bottom of the evaporation chamber are composed of a transparent material, to allow light to pass through the evaporation chamber and reach the front surface of the photovoltaic cell. The front surface of the photovoltaic cell may be in direct contact with the outside surface of the bottom of the evaporation chamber to allow conductive heat transfer, or may alternately be positioned in close proximity to the outside surface of the bottom of the evaporation chamber. The front surface of the photovoltaic cell is exposed to sunlight or another light source. This exposure results in power generation by the photovoltaic cell and also heats the sides of and the air inside the evaporation chamber. Untreated water is subsequently introduced into the evaporation chamber. The untreated water may preferably be stored in an untreated water chamber before introduction into the evaporation chamber. The untreated water may preferably be introduced into the evaporation chamber using a pump. Upon contacting the heated air and inside surfaces of the evaporation chamber, a portion of the untreated water evaporates to generate water vapor. The untreated water is heated directly by contacting the heated air and the inside surfaces of the evaporation chamber, without the use of a separate heating unit or heat exchange unit. The water vapor is then removed from the evaporation chamber and transported to a condensation chamber. The portion of the untreated water that does not evaporate may preferably be transported back into the untreated water chamber. The water vapor is cooled in the condensation chamber to yield desalinated water. The water vapor may preferably be cooled using a cooling plate.
The present disclosure describes an apparatus that may be used to generate desalinated water from a supply of untreated water using a photovoltaic cell.
As used herein, the term “photovoltaic cell” may refer to a single photovoltaic cell or an array of photovoltaic cells connected together in series or in parallel.
It is well established that the front surface of a photovoltaic cell generates thermal energy when exposed to sunlight. By enclosing the area around the front surface of a photovoltaic cell, the air surrounding said surface may reach temperatures in excess of 140 degrees fahrenheit.
The front surface of the photovoltaic cell is adjacent to the bottom of an evaporation chamber. The top and bottom of the evaporation chamber are composed of a transparent material, to allow light to pass through the evaporation chamber and reach the front surface of the photovoltaic cell. The front surface of the photovoltaic cell may be in direct contact with the outside surface of the bottom of the evaporation chamber to allow conductive heat transfer, or may alternately be positioned in close proximity to the outside surface of the bottom of the evaporation chamber. The front surface of the photovoltaic cell is exposed to sunlight or another light or other electromagnetic radiation source. This exposure results in power generation by the photovoltaic cell and also heats the sides of and the air inside the evaporation chamber. Untreated water is subsequently introduced into the evaporation chamber. The untreated water may preferably be stored in an untreated water chamber before introduction into the evaporation chamber. The untreated water may preferably be introduced into the evaporation chamber using a pump. Upon contacting the heated air and inside surfaces of the evaporation chamber, a portion of the untreated water evaporates to generate water vapor. The untreated water is heated directly by contacting the heated air and/or the inside surfaces of the evaporation chamber, without the use of a separate heating unit or heat exchange unit. The water vapor is then removed from the evaporation chamber and transported to a condensation chamber. The portion of the untreated water that does not evaporate may preferably be transported back into the untreated water chamber. The water vapor is cooled in the condensation chamber to yield desalinated water. The water vapor may preferably be cooled using a cooling plate.
The efficiency of photovoltaic cells is known to be optimized within specific temperature ranges. If the temperature at the surface of a photovoltaic cell is above or below the optimum temperature range, the efficiency of the photovoltaic cell decreases. Thus, an additional advantage provided by the disclosed apparatus is to optimize the efficiency of the photovoltaic cell. As the photovoltaic cell is heated by incident sunlight, it heats the air and untreated water in the evaporation chamber. The water is then collected in the condensation chamber as described. This heat transfer lowers the temperature within the evaporation chamber and the temperature of the surfaces of the evaporation chamber, which in turn lowers the temperature at the front surface of the photovoltaic cell that is adjacent to the evaporation chamber and is preferably in direct contact therewith. By controlling the rate at which untreated water is introduced into the evaporation chamber, it is possible to maximize the efficiency of the system by maintaining the front surface of the photovoltaic cell at its optimum operating temperature. This ensures optimum use of available energy sources, and leads to synergy between the generation of treated water and the operation of the photovoltaic cell at peak efficiency.
In some alternate implementations, the temperature of the photovoltaic cell is controlled by partial evacuation of the evaporation chamber to generate pressures below atmospheric pressure. In such implementations, preferred pressure ranges may be between about 0.10 atm and about 0.99 atm. The evaporation chamber is constructed to be able to withstand the targeted pressure differential without compromising its short-term or long-term structural integrity or incurring other damage. The pressure within the evaporation chamber may be lowered to a desired pressure using a vacuum pump that is operationally connected to the evaporation chamber at a vacuum pump inlet port. One or more valves may be situated at the vacuum pump inlet port to allow control of the pressure within the evaporation chamber. The pressure within the evaporation chamber may be monitored using one or more pressure gauges. The pressure gauges may be configured to automatically open or close the one or more valves when a threshold pressure is achieved.
Partial evacuation of the evaporation chamber may promote consistent evaporation even under varying ambient temperature conditions.
Alternately or additionally, untreated water that is introduced into the evaporation chamber may be used to lower the temperature of the photovoltaic cell to within a desired temperature range.
In some preferred implementations, electrical energy produced by the photovoltaic cell may preferably be used to power various components of the apparatus.
In some preferred implementations, some of the energy produced by the photovoltaic cell may power the cooling plate used to condense the water vapor generated in the evaporation chamber.
In some preferred implementations, some of the energy produced by the photovoltaic cell may be stored in a battery or other energy storage system. The energy stored in a battery may be used to power other components of the apparatus such as a wiper, humidistat, controller, motor, counterweight, pump, or other optional components described herein.
In some alternate preferred implementations, some of the energy produced by the photovoltaic cell may be stored using a counterweight system. Energy produced by the photovoltaic cell may be used to raise a counterweight, where the energy is stored as potential energy. The counterweight may subsequently be lowered to release the stored potential energy when there is insufficient sunlight for the photovoltaic cell to operate effectively. The energy generated by lowering the counterweight may be used to power the system at night or at other times when there is insufficient sunlight for the photovoltaic cell to operate effectively. Some of the energy generated by lowering the counterweight may also be used to power other components of the apparatus such as a wiper, humidistat, controller, motor, pump, or other optional components described herein. Mechanical counterweight systems are well known in the art, and the counterweight system used may be any counterweight system that is configured for coupling with a photovoltaic cell as described herein.
In some implementations, the apparatus may further include a wiper, wherein the wiper may be used to mechanically remove residual deposits from one or more inside surfaces of the evaporation chamber. These residual deposits may be introduced via the untreated water and may otherwise obstruct light from reaching the front surface of the photovoltaic cell.
In some implementations, the wiper may be operated by a motor, by using a counterweight, or by using both a motor and a counterweight. The wiper may preferably be operated according to a frequency that maximizes the difference between the energy produced by the photovoltaic cell and the energy consumed by operating the wiper.
In some implementations, a wash system may be used to remove mineral deposits and/or residues generated during desalination from the evacuation chamber. Mineral deposits on the surfaces of the evaporation chamber may result in degraded performance of the apparatus, as such deposits may inhibit radiant light from reaching the photovoltaic cell.
In some implementations, the wash system includes one or more small holes at the top of the evacuation chamber that are operationally connected to the condensation chamber via tubing. The tubing is connected to a pump, and the pump is connected to the condensation chamber. The pump may be the same pump used to introduce untreated water into the evaporation chamber, where one or valves are used to control which water source is used to pump water into the evaporation chamber at a specific time, or may alternately be a separate pump. Desalinated water from the condensation chamber is intermittently introduced into the evaporation chamber and allowed to cascade over the inside surfaces of the evaporation chamber to wash away deposits that have formed on the surfaces of the evaporation chamber. The timing and rate of introduction of water from the condensation chamber into the evaporation chamber may be controlled by one or more valves. These valves may be manually controlled or may alternately be controlled by a microcontroller that allows for automated opening and closing of the valves. Effluent generated by washing away the deposits is preferably discarded via a drain system, so as not to increase the salinity of the water in the untreated water chamber.
The pressure of cascading water used in the wash system may be controlled to maximize cleaning efficiency. In some implementations, a biodegradable cleaning agent may be used to enhance cleaning efficiency and effectiveness.
In some implementations, the wash system may further incorporate a wiper for mechanically removing deposits from the front surface of the photovoltaic cell, as described above.
In some implementations, the apparatus may further include a humidistat, wherein the humidistat may be used to monitor and adjust the humidity and temperature within the evaporation chamber. The rate of introduction of untreated water may preferably be controlled by the humidistat to optimize performance of the apparatus by maintaining high temperature and high humidity in the evaporation chamber.
In some implementations, the apparatus may further include two or more aerators, wherein at least one aerator may be used to introduce air bubbles into the untreated water stream entering the evaporation chamber and at least one other aerator may be used to allow excess air or other gases to exit the evaporation chamber to maintain equilibrium and avoid a buildup of pressure. The introduction of air bubbles into the untreated water stream will increase the surface area of contact between the heated air in the evaporation chamber and the untreated water. This results in a higher rate of evaporation.
Untreated salt water with 35 ppt salt was generated using Instant Ocean. Power generated by the photovoltaic cell was used by a controller and 12 volt DC water pump to pump untreated water into the evaporation chamber. A cooling plate comprising thermoelectric modules situated between two copper plates was employed in the condensation chamber. When the cooling plate was exposed to current, the thermoelectric modules rendered one copper plate cool and the other copper plate hot. The thermoelectric modules were configured so that the cool plate was on the inside of the condensation chamber. The cool plate was used to condense water vapor generated in the evaporation chamber. The salinity of the condensed water vapor was measured and determined to be 1.1 ppt.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the invention disclosed herein. Although the various inventive aspects are disclosed in the context of certain illustrated embodiments, implementations, and examples, it should be understood by those skilled in the art that the invention extends beyond the specifically disclosed embodiments to other alternative embodiments and/or uses of the invention and obvious modifications and equivalents thereof. In addition, while a number of variations of various inventive aspects have been shown and described in detail, other modifications that are within their scope will be readily apparent to those skilled in the art based upon reviewing this disclosure. It should be also understood that the scope of this disclosure includes the various combinations or sub-combinations of the specific features and aspects of the embodiments disclosed herein, such that the various features, modes of implementation, and aspects of the disclosed subject matter may be combined with or substituted for one another. The generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the disclosure. Thus, the present disclosure is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Similarly, the disclosure is not to be interpreted as reflecting an intent that any claim set forth below requires more features than are expressly recited in that claim. Rather, as the following claims reflect, inventive aspects may reside in a combination of fewer than all features of any single foregoing disclosed embodiment.
Each of the foregoing and various aspects, together with those set forth in the claims and summarized above or otherwise disclosed herein, including the figures, may be combined without limitation to form claims for a device, apparatus, system, method of manufacture, and/or method of use.
All references cited herein are hereby expressly incorporated by reference.
This application is a continuation-in-part of U.S. patent application Ser. No. 17/661,901, filed on May 3, 2022, which is a continuation of U.S. patent application Ser. No. 17/009,717, filed on Sep. 1, 2020 and issued as U.S. Pat. No. 11,318,395 on May 3, 2022, which is a continuation-in-part of U.S. patent application Ser. No. 16/424,473, filed on May 28, 2019 and issued as U.S. Pat. No. 10,759,677 on Sep. 1, 2020, which is a continuation-in-part of U.S. patent application Ser. No. 15/614,599, filed on Jun. 5, 2017, which is a continuation-in-part of U.S. patent application Ser. No. 15/379,630, filed on Dec. 15, 2016, the disclosures of which are hereby incorporated in their entireties by reference.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17009717 | Sep 2020 | US |
| Child | 17661901 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 17661901 | May 2022 | US |
| Child | 18796061 | US | |
| Parent | 16424473 | May 2019 | US |
| Child | 17009717 | US | |
| Parent | 15614599 | Jun 2017 | US |
| Child | 16424473 | US | |
| Parent | 15379630 | Dec 2016 | US |
| Child | 15614599 | US |
