A DEVELOPMENT OF SINGLE SLOPE SOLAR STILL USING NATURAL FIBER-REINFORCED COMPOSITES

Abstract

The present invention pertains to a single-slope solar still 100 designed for efficient water distillation using natural fiber-reinforced composite materials. The solar still 100 comprises a basin 1 with a north wall 1A, east wall 1B, west wall 1C, and south wall 1D. The east wall 1B and west wall 1C are covered with transparent glass covers 7A and 7B to maximize solar radiation absorption. The black cotton wick 2 is attached vertically to the north wall 1A, east wall 1B, and west wall 1C. The drip pipe 5 is positioned within the basin 1 to supply preheated water drop-by-drop from a preheated water supply tank 3, which is regulated by a feed regulator 6 to control water flow precisely.

Specification

Description:FIELD OF INVENTION:
[0001] The present invention generally relates to solar distillation technology. More specifically, the present invention relates to the development of a single-slope solar still for water distillation, utilizing natural fiber-reinforced composite materials for enhanced efficiency and sustainability.
BACKGROUND OF THE INVENTION:
[0002] A basic requirement for maintaining human health and wellbeing is having access to clean and drinkable water. However, the availability of freshwater resources is increasingly threatened by pollution, industrial activities, and population growth. Conventional water purification techniques, such as boiling, filtration, chlorination, ultraviolet disinfection, reverse osmosis, ion exchange, and desalination, are effective but often come with high energy costs and environmental impacts.
[0003] Among various water purification technologies, solar stills offer a sustainable and energy-efficient solution. A solar still utilizes solar energy to evaporate and condense water, providing a means to purify brackish or contaminated water. However, traditional solar still designs face limitations in terms of efficiency, scalability, and practicality, especially in densely populated or urban environments.

[0004] Subbarama Kousik Suraparaju, et al. "Combined enhancement of evaporation and condensation rates in the solar still for augmenting the freshwater productivity using energy storage and natural fibres" The study introduces a modified solar still (MSS) with a hollow-finned absorber basin integrated with energy storage and novel pond fibers, aiming to improve heat absorption and retention. To enhance condensation, the MSS employs sisal fibers and a water dripping arrangement on the top glass. The results show that the MSS achieves a 12% increase in water temperatures and a 30% reduction in glass temperatures compared to conventional solar stills (CSS). Consequently, the MSS exhibits a 126% increase in productivity, with notable reductions in cost per liter (CPL) and payback period (PP), making it a more efficient and cost-effective solution for solar distillation.

[0005] The above-mentioned prior art does not address the long-term durability of the materials and design features introduced, nor does it provide detailed information on maintenance requirements and potential issues associated with the advanced components like hollow-finned absorbers and pond fibers.

[0006] Therefore, there is a need for innovative improvements in solar still design and materials.
OBJECTS OF INVENTION:
[0007] The primary object of the present invention is to provide a single slope solar still made from a natural fiber-reinforced composite material that offers improved insulation and reduces energy loss, enhancing overall efficiency in water purification.
[0008] Another object of the present invention is to provide a single slope solar still that implements a vertical basin approach in conjunction with a traditional basin to maximize water evaporation rates.
[0009] Another object of the present invention is to provide a single slope solar still that utilizes a drop-by-drop feeding mechanism to supply preheated water to the solar still, ensuring a consistent water level and improving the rate of evaporation and distillation.
[0010] Another object of the present invention is to provide a single slope solar still that improves the efficiency of the solar still to lower the energy requirements and operational costs associated with water purification, making it a cost-effective alternative to traditional methods.
[0011] Another object of the present invention is to provide a still that can be compact, practical, and suitable for both urban and rural environments, addressing the diverse needs for potable water.

SUMMARY OF INVENTION:
[0012] The present invention pertains to a single slope solar still fabricated from the natural fiber-reinforced composite (NFRC) materials, which offer superior insulation and environmental sustainability compared to conventional materials.
[0013] In an aspect of the present invention, a single-slope solar still comprising a basin having a north wall, an east wall, a west wall, and a south wall, wherein the basin, the north wall, and the south wall are constructed from natural fiber-reinforced composite (NFRC) materials, a black cotton wick is attached vertically to the internal surface of the north wall, the east wall, and the west wall, a preheated water supply tank is filled with preheated water and supported by a support structure, a drip pipe is arranged within the basin for supplying the preheated water drop-by-drop from the preheated water supply tank, a feed regulator is provided to control the supply rate of preheated water from the preheated water supply tank, a transparent glass cover is covered the top portion of the basin.
[0014] In an aspect of the present invention, the natural fiber-reinforced composite (NFRC) materials include resin comprising epoxy and hardener.
[0015] In an aspect of the present invention, the natural fiber-reinforced composite (NFRC) materials include natural fibers comprising date palm and coir fibers.
[0016] In an aspect of the present invention, the transparent glass cover over the top portion of the basin is inclined at 15° to facilitate the condensation of evaporated water and direct it toward an external distillation collection system.
[0017] In one aspect of the present invention, the east wall and west wall are made of transparent glass covers, respectively, allowing maximum sunlight to enter the basin.

BRIEF DESCRIPTION OF THE DRAWINGS:
[0018] The invention has other advantages and features which will be more readily apparent from the following detailed description of the invention and the appended claims, when taken in conjunction with the accompanying drawings, in which:
Fig. 1 illustrates the schematic diagram of solar still fabricated by natural fiber-reinforced composite material
Fig. 2 illustrates the transparent glass cover arranged on solar still
Fig. 3 illustrates the drip pipe inside the basin and black cotton wick covered on east, west and north walls
Fig. 4 illustrates the basin and walls fabricated with natural fiber-reinforced composite material
Fig. 5A illustrates the graphical representation of solar radiation falling on the natural fiber-reinforced composite solar still and Traditional solar still
Fig. 5B illustrates the graphical representation of hourly temperature variation of ambient and basin water of the natural fiber-reinforced composite solar still and Traditional solar still
Fig. 5C illustrates the graphical representation of the hourly variation of distilled water of the natural fiber-reinforced composite solar still and Traditional solar still
Fig. 5D illustrates the graphical representation of the hourly variation of instantaneous efficiency of the natural fiber-reinforced composite solar still and Traditional solar still

DETAILED DESCRIPTION OF THE INVENTION:
[0019] While the invention has been disclosed with reference to certain embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the scope of the invention. In addition, many modifications may be made to adapt to a particular situation or material to the teachings of the invention without departing from its scope.

[0020] Throughout the specification and claims, the following terms take the meanings explicitly associated herein unless the context clearly dictates otherwise. The meaning of "a", "an", and "the" include plural references. The meaning of "in" includes "in" and "on." Referring to the drawings, like numbers indicate like parts throughout the views. Additionally, a reference to the singular includes a reference to the plural unless otherwise stated or inconsistent with the disclosure herein.

[0021] The figures and protocols have been represented where appropriate by conventional representations in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.

[0022] The present invention discloses a solar still is constructed from natural fiber-reinforced composite (NFRC) materials, which provide excellent thermal insulation and reduce heat loss. The solar still employs a single-slope design with a vertical basin approach. The single-slope design of the solar still incorporates a basin with an inclined glass cover. This design maximizes the exposure of the water to solar radiation and also ensures efficient condensation and collection of distilled water. The inclined angle allows for a more uniform distribution of sunlight across the water surface, enhancing the evaporation process.

[0023] As depicted in Fig. 1, Fig.2, and Fig.3, the single slope solar still 100 includes a basin 1 with north wall 1A, east wall 1B, west wall 1C, and south wall 1D. The basin 1 along with the north wall 1A and the south wall 1D are constructed from natural fiber-reinforced composite materials, providing structural integrity and insulation. The black cotton wick 2 is attached vertically to the interior surfaces of the north wall 1A, east wall 1B, and west wall 1C. The black cotton wick 2 facilitates capillary action, creating a thin layer of water for improved solar radiation absorption and evaporation. The preheated water supply tank 3 is positioned on a support structure 4 to maintain an elevated and stable placement. The drip pipe 5 is arranged within the vertical basin 1 to deliver preheated water from the preheated water supply tank 3 in a controlled, drop-by-drop manner. The flow of preheated water is regulated by a feed regulator 6, which precisely controls the water supply from the preheated water supply tank 3, ensuring optimal water levels and efficient operation. The east wall 1B and west wall 1C are made of transparent glass covers 7A and 7B, respectively, allowing maximum sunlight to enter the basin 1. Additionally, the top portion 8 of the basin 1 is covered with a transparent glass cover 7 that is inclined at a 15° angle, to facilitate efficient condensation and collection of distilled water. A 15° angle is particularly effective as it aids in the efficient flow of condensed water droplets down to the basin 1, leveraging gravity to prevent droplets from falling back into the basin 1, thus enhancing collection efficiency. Furthermore, the inclination angle of the glass cover 7 influences heat transfer processes as well as the amount of direct solar energy received by the solar still 100.

[0024] Fig. 4 illustrates the basin 1, the north wall 1A, and the south wall 1D are constructed from natural fiber-reinforced composite (NFRC) materials. These NFRC materials are chosen for their excellent thermal insulation properties, which minimize heat loss and enhance the overall efficiency of the solar distillation process. The natural fiber-reinforced composite materials used in the solar still 100 consist of a composite blend. This blend includes resin components, such as epoxy combined with a hardener, and natural fibers derived from materials like date palm and coir.

DETAILS OF EXPERIMENT:
[0025] A series of experiments were conducted to evaluate the performance of two types of solar stills. The two models tested were the Natural Fiber-Reinforced Composite Solar Still (NFRC SS) as described in the present invention, and a Traditional Solar Still (TSS). The experiments aimed to compare various performance metrics of these solar stills under similar conditions.

[0026] As illustrated in Figure 5A, solar radiation measurements were taken for both solar stills. The maximum solar radiation intensity received on the inclined glass cover was recorded at 1085 W/m² at 1:00 pm. For the east and west walls, the maximum solar radiation intensities were measured to be 746 W/m² at 10:00 am and 703 W/m² at 4:00 pm, respectively.

[0027] Figure 5B displays the hourly temperature variations of the ambient environment and the basin water for both the NFRC SS and TSS. The maximum ambient temperature recorded was 42°C. The basin water temperature for the NFRC SS peaked at 66°C, whereas the basin water temperature for the TSS reached 60°C. The higher basin water temperature in the NFRC SS is attributed to the drop-by-drop feeding of preheated water, which enhances heat retention and increases the water temperature more effectively than the TSS.

[0028] Figure 5C illustrates the hourly variation in distilled water production for both solar stills. The NFRC SS achieved a maximum distillate output of 178 mL at 1:00 pm, while the TSS produced a maximum of 120 mL at the same time. Over the course of a day, the total distillate production was 963 mL for the NFRC SS compared to 673 mL for the TSS.

[0029] Figure 5D shows the hourly variation in instantaneous efficiency for both solar stills. The NFRC SS exhibited a maximum instantaneous efficiency of 40.3% at 6:00 pm, whereas the TSS reached a maximum instantaneous efficiency of 33.01% at 5:00 pm. The daily thermal efficiency for the NFRC SS was found to be 28.6%, while the TSS had a daily thermal efficiency of 22.9%. This indicates that the NFRC SS is 24.89% more efficient than the TSS, demonstrating superior performance in terms of both distillate output and thermal efficiency.


[0030] In an embodiment, the natural fiber-reinforced composite materials consist of a blend of resin such as epoxy with hardener, and natural fibers, such as date palm and coir fibers.

[0031] In an embodiment, the single-slope design of the solar still 100 features a basin 1 with a transparent glass cover 7 which is inclined at 15°.

[0032] In an embodiment, the transparent glass cover 7 over the top portion 8 of the basin 1 is inclined at 15° to facilitate the condensation of evaporated water and direct it towards an external distillation collection system. Studies in prior arts have shown that aligning the glass inclination angle with the latitude of the experimental location maximizes distillate output. The thermal efficiency of the solar still is most effective when the glass inclination angle is adjusted to be within ±10 degrees of the latitude of the location where the experiments are conducted and also have confirmed that the distillate output of a solar distiller is optimized when the glass inclination angle is set to match the latitude of the location where the experiments are conducted. This alignment ensures that the distiller captures the maximum amount of direct solar radiation throughout the day, enhancing its efficiency.

[0033] In an embodiment, the transparent glass covers (7, 7A,7B) are 4 mm thick and have a transmissivity of 0.9, ensuring high transmission of solar energy.

[0034] In an embodiment, the north wall 1A has an area of 50 cm × 24 cm², while the south wall 1D measures 50 cm × 10 cm². Both the east and west walls each cover an area of 620 cm².

[0035] In an embodiment, the basin 1 has dimensions of 50 cm by 50 cm², providing ample space for water to be heated.

[0036] In an embodiment, the preheated water from a preheated water supply tank 3 can significantly improve the efficiency of a solar still 100. The initial higher temperature of preheated water reduces the energy required to reach the evaporation point, thereby accelerating the evaporation process. This higher initial temperature also contributes to greater thermal momentum, as the water retains its heat for a longer duration, sustaining a higher rate of evaporation. Additionally, preheated water reduces the amount of heat needed to initiate evaporation, leading to decreased heat loss to the environment. Furthermore, the increased temperature differential between the preheated water and the cooler glass cover 7 improves heat transfer efficiency, optimizing the overall performance of the solar still 100.

[0037] Although a particular exemplary embodiment of the invention has been disclosed in detail for illustrative purposes, it will be recognized by those skilled in the art that variations or modifications of the disclosed invention, including the rearrangement in the configurations of the parts, changes in steps and their sequences may be possible. Accordingly, the invention is intended to embrace all such alternatives, modifications, and variations as may fall within the spirit and scope of the present invention.

[0038] The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching.

ADVANTAGES OF THE INVENTION:

[0039] The present invention provides a single-slope solar still that increases the evaporation rate, leading to higher distillate output compared to traditional solar stills.
[0040] The present invention provides a single-slope solar still that occupies less space compared to traditional large solar stills, making it suitable for use in urban or densely populated areas.
[0041] The present invention provides a single-slope solar still wall that maximizes the evaporation rate, resulting in a higher distillate output compared to traditional solar stills.
, Claims:1. A single-slope solar still 100, comprising:
a basin 1 having a north wall 1A, an east wall 1B, a west wall 1C, and a south wall 1D, wherein the basin 1, the north wall 1A, and the south wall 1D are constructed from natural fiber-reinforced composite (NFRC) materials;
a black cotton wick 2 attached vertically to the internal surface of the north wall 1A, the east wall 1B, and the west wall 1C;
a preheated water supply tank 3 filled with preheated water and supported by a support structure 4;
a drip pipe 5 arranged within the basin 1 for supplying the preheated water drop-by-drop from the preheated water supply tank 3;
a feed regulator 6 provided to control the supply rate of preheated water from the preheated water supply tank 3;
a transparent glass cover 7 covered the top portion 8 of the basin 1.

2. The single-slope solar still 100 as claimed in claim 1, wherein the natural fiber-reinforced composite (NFRC) materials include resin comprising epoxy and hardener.

3. The single-slope solar still 100 as claimed in claim 1, wherein the natural fiber-reinforced composite (NFRC) materials include natural fibers comprising date palm and coir fibers.

4. The single-slope solar still 100 as claimed in claim 1, wherein the transparent glass cover 7 over the top portion 8 of the basin 1 is inclined at 15° to facilitate the condensation of evaporated water and direct it towards an external distillation collection system.
5. The single-slope solar still 100 as claimed in claim 1, wherein the east wall 1B and west wall 1C are made of transparent glass covers 7A and 7B, respectively, allowing maximum sunlight to enter the basin 1.

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