DESC:
FIELD
The present disclosure relates to the field of mechanical engineering. Particularly, the present disclosure relates to a paddlewheel apparatus for a raceway pond.
BACKGROUND
Raceway ponds are generally used for aqua culture production. Raceways ponds have long, shallow, and looped channels, and are used for growing aqua culture so as to produce nutraceuticals and remediate or treat wastewater. Raceway ponds typically utilize sunlight as the main energy source for photosynthetic reactions, to produce biomass. For an optimum growth of the aqua culture, raceways ponds require a mechanism not only to keep the aqua culture suspended in the medium so as to avoid stagnation, but also to prevent the aqua culture from either remaining at the bottom of the pond where there is too little sunlight exposure, or from remaining at the surface of the pond where the sunlight exposure may be too high. Therefore, in order to utilize the sunlight, an efficient mixing, viz., a horizontal and vertical mixing,in raceway ponds is important.
Conventionally, raceway ponds are driven by paddle wheels or mixers to create a current and to circulate the aqua culture.Typically, a paddle wheel is a hub comprising 6 to 8 paddles that are fixed to a cylindrical shaped drum or a disc. There are various designs of the paddles disclosed in the following prior arts.
The US Patent Document Number 3855370 suggests a mixer comprising paddles, which are straight, elongated, and partially or completely submerged in the culture. The US Patent Document Number US8142167 suggests a paddlewheel apparatus that comprises straight elongated paddles.
However, a mixer comprising straight paddledesign has a poor pumping efficiency. Hence, in order to attain a required flow rate, it is necessary to perform higher rotations per minute of the paddles, thereby resulting in higher power consumption.
Moreover, in the conventional raceway ponds, a pond depth is approximately 15 cm to 30 cm, andthe conventional paddlesare capable of attaining a velocity approximately in the range of 20 cm/s to 40 cm/s, which is low. Particularly, in the case of conventional paddles, energy conversion to momentum is very low. This is because of the energy losses caused by the drag or drag force associated with the flow in the paddle section.
There is, therefore, felt a need for an alternative which consumes less power and provides improved pumping efficiency, improved horizontal and vertical mixing, and reduced drag associated with the flow.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
An object of the present disclosure is toprovide an alternative for improving pumping efficiency.
Another object of the present disclosure is to provide an alternative forimproving a horizontal and vertical mixing.
Still another object of the present disclosure is to provide an alternative forreducing the drag associated with the flow.
Yet another object of the present disclosure is to provide an alternative for reducing power consumption.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure envisagesa paddlewheel apparatus for a raceway pond. The paddlewheel apparatus includes a plurality of elongated paddles. The plurality of elongated paddles are coupled to a rotatable disc such that each elongated paddle is obliquely disposed on the rotatable disc and extends radially outwards from the periphery of the rotatable disc.Each elongated paddle is operatively laterally bent at a predefined distance along its length at an angle of around 45 degree in the direction of rotation of said rotatable disc.
The elongated paddle can be at least partially submerged in the culture in the raceway pond.
The rotatable disc can be annular in shape.
The lateral bend of the elongated paddle can be adjustable with respect to the total depth of the culture in the raceway pond.
The predefined distance of the lateral bend can be directly proportional to the total depth of the culture in the raceway pondand it varies in relation to a portion of the elongated paddle immersed in the culture.
The predefined distance of the lateral bend can be at a length of 30% to 70% of the portion of the elongated paddle immersed in the culture.
The predefined distance of the lateral bend can be at around halfway mark of the portion of the elongated paddle immersed in the culture.
A minimum ground clearance can be provided between a distal end of the elongated paddle and a floor of the raceway pond.
A portion of the elongated paddle that needs to be submerged in the culture can be calculated using computational fluid dynamics simulations.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
A paddlewheel apparatus for a raceway pondwill now be described with the help of the accompanying drawing, in which:
Figure 1illustrates a schematic view of a raceway pond with a paddlewheelapparatusin accordance with the present disclosure;
Figure 2 illustrates a schematic view of the paddlewheel apparatusof Figure 1;
Figure 3 illustrates Computational Fluid Dynamics (CFD) simulations for a conventional paddlewheel design in accordance with the present disclosure;
Figure 4 illustrates CFD simulations for the paddle wheel apparatus with a bend at 0 m from the top of the length of an elongated paddle immersed in the culture in the raceway pond in accordance with the present disclosure;
Figure 5illustrates CFD simulations for the paddle wheel apparatus with a bend at 0.08 m from the top of the length of the elongated paddle immersed in the culture in the raceway pond in accordance with the present disclosure; and
Figure 6illustrates a performance curve of the paddlewheel apparatus with a bend at different locations on the elongated paddle immersed in the culture in the raceway pond in accordance with the present disclosure.
Table illustrates the raceway pond and its components that are represented by the following reference numerals:
components Reference numeral
raceway pond (100)
paddlewheel apparatus (101)
plurality of elongated paddles (P1 to P6)
rotatable disc (D)
direction (A)
laterally bent (L)
predefined distance (a)
an angle of around 45 degree (o)
total depth (b3)
portion (p)
surface (s)
minimum ground clearance (g)
length (b1)
length (b2)
detailed description
As described herein above, there are certain drawbacks associated with a conventional paddle wheel design, for instance:
pumping efficiency is poor;
energy conversion efficiency is low due to the energy losses from the drag associated with the flow in the paddle section; and
the amount of power consumed or required to attain a desired flow rate is high.
The present disclosure, therefore, provides a paddlewheel apparatus for a raceway pond so as to obviate the above mentioned drawbacks.
The paddlewheel apparatus is described with reference to Figure 1 and Figure 2.
The paddlewheel apparatus (101) for a raceway pond (100) comprises a plurality of elongated paddles (P1 to P6). The plurality of elongated paddles (P1 to P6) are coupled to a rotatable disc (D) such that each elongated paddle is obliquely disposed on the rotatable disc (D), and it extends radially outwards from the periphery of the rotatable disc (D). Each elongated paddle is operatively laterally bent (L) at a predefined distance (a) along its length at an angle of around 45 degree (o) in the direction (A) of rotation of the rotatable disc (D).
Particularly, the introduction of the lateral bend (L) in the direction of rotation (A) of the rotatable disc (D) ensures a continuous movement of the cultureboth in a horizontal direction and a vertical direction. The lateral bend (L) facilitates in reducing the drag associated with the flow, thereby:
improving the pumping efficiency by increasing the amount of the culture pumped in the direction of rotation (A) without changing or varyingtherotations per minute of the plurality of elongated paddles (P1 to P6); and
increasing the flow rate of the culture in the raceway pond (100) by consuming less amount power as compared to that consumed by the conventional paddle wheel design.
The rotatable disc (D)can be annular in shape.
The diameter of the rotatable disc (D) can be 0.5 m.
The lateral bend (L) of the elongated paddle is adjustable with respect to the total depth (b3) of the culture in the raceway pond (100).
The predefined distance (a) of the lateral bend (L) can be directly proportional to the total depth (b3) of the culture in the raceway pond (100),and it can vary in relation to a portion (p) of the elongated paddle immersed in the culture.
The total depth (b3) of the culture in the raceway pond (100) can be 0.2 m.
The predefined distance (a) of the lateral bend (L) can be at a length of 30% to 70% of the portion of the elongated paddle immersed in the culture.
The predefined distance (a) of the lateral bend (L) can be at around halfway mark of the portion of the elongated paddle immersed in the culture.
The predefined distance (a) of the lateral bend (L) can be 0.08 m from the surface (s) of the culture.
A minimum ground clearance (g)can be provided between a distal end (not shown in Figures 1 and 2) of the elongated paddle and a floor (not shown in Figures 1 and 2) of the raceway pond (100).
The minimum ground clearance (g) can be 0.04 m.
The elongated paddle can be at least partially submerged in the culture in the raceway pond (100).
The length (b1) of the elongated paddle which gets immersed in the culture in the raceway pond (100) can be 0.16 m from the surface (s) of the culture.
The length (b2) of the elongated paddle which is above the surface (s) of the culture can be 0.1 m.
In accordance with the present disclosure, a portion of the elongated paddle that needs to be submerged in the culture is calculated using computational fluid dynamics simulations.
The present disclosure is further described in light of the following experiments which is set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following laboratory scale experiments can be scaled up to industrial/commercial scale.
Experiment: CFD simulations
Trials were conducted to identify an appropriate location of the lateral bend (L) in the plurality of elongated paddles (P1 to P6) of the paddlewheel apparatus (101). Initial CFD simulations predicted that the introduction of the lateral bend (L) facilitates in increasing the pumping efficiency, but at a higher energy or pumping cost.
CFD simulations were conducted to optimize the design to achieve a better pumping efficiency at lower power consumption. CFD simulations were conducted for a location of the lateral bend (L) in the elongated paddle at 0.12 m, 0.08 m, 0.04 m, 0.02 m, and 0 m from the top of the length of the paddle immersed in the culture in the raceway pond (100).
Figures 3, 4,and 5illustrate CFD simulations for the conventional paddlewheel design,the paddlewheel apparatus with a bend at 0 m and 0.08 m respectively from the top of the length of the elongated paddle immersed in the culture in the raceway pond (100). The results obtained from the CFD simulations are tabulated in Table-1.
Table-1:
Immersed
depth
(A) RPM
(B) Power
(C) Velocity generated (D) Pumping
number
(E) Overall
performance
(F)
M W m/s %
Location of the bend in 0.16 m of paddle length immersed in the culture

0.00 12.00 276.85 0.45 0.34 84%
0.02 12.00 191.96 0.40 0.30 105%
0.04 12.00 164.19 0.35 0.26 108%
0.08 12.00 131.77 0.29 0.22 111%
0.12 12.00 133.71 0.28 0.21 107%
Normal Straight Paddle (conventional) 0.16 12.00 107.68 0.21 0.16 100%
Referring to Table-1, it is found that, the pumping efficiency is the lowest for the conventional paddlewheel design(straight paddlewheel), i.e., the paddlewheel with no lateral bend, and the pumping efficiency increases with the introduction of thelateral bend (L), irrespective of its location. This is because; the lateral bend (L) facilitates a significant reduction in the amount of the drag associated with the flow. This clearly indicates a relationship between the lateral bend (L) on the elongated paddle and the pumping efficiency.
From Table-1, it is found that, the pumping efficiency is highest when a lateral bend (L) of 45° is introduced right at 0 m. However, the amount of power consumed is significantly high, i.e., 276.85 W, thereby making it unviable.
The overall performance of the paddlewheel with 45° bend is calculated by a formula provided herein below.
Overall Performance= (Pumping no((45° Bend)/(Straight Paddle)))/(Power ((45° Bend)/(Straight Paddle)))
It is clearly evident from Table-1 (column F) that introducing a lateral bend in the elongated paddle at an increased distance from the top of the elongated paddle immersed in the culture results in higher pumping efficiency and lower power consumption. However, the maximum pumping efficiency (111%) with lower power consumption (131.77W) is achieved when a bend of 45° is introduced at 0.08m from the top of the elongated paddle immersed in the culture.
Moreover, the performance curve of the paddlewheel apparatus (100) with the lateral bend (L) at different locations, viz., 0.0m, 0.04m, 0.08m, 0.12m, 0.16m, and 0.20m, from the top of the elongated paddle immersed in the culture in the raceway pondis illustrated in Figure 6.
It is evident from Figure 6 that the maximum performance of the paddlewheel apparatus (100) is achieved by introducing a lateral bend on the plurality of elongated paddles (P1 to P6) at 0.06 to 0.10 m (represented by a portion A in Figure 6) from the top of the length of the elongated paddle immersed in the culture.
Moreover, with this configuration, the pumping efficiency of the paddlewheel apparatus (100) can be improved by more than 35%.
technical advances and economical significance
The present disclosure described herein above has several technical advantages including, but not limited to, the realization ofa paddlewheel apparatusthat:
provides higher pumping efficiency and higher overall performance efficiency as compared to the conventional paddlewheel designs;
provides the same flow velocity by operating at a lower rotation per minute, thereby reducing the power consumption;
provides a significant reduction in the drag associated with the culture flow;
provides an improved vertical and horizontal mixing;
provides optimized power consumption and high energy conversion efficiency; and
reduces the energy losses associated with the flow.
The disclosure has been described with reference to the accompanying embodiments which do not limit the scope and ambit of the disclosure. The description provided is purely by way of example and illustration.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein.
The foregoing description of the specific embodiments so fully revealed the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein. ,CLAIMS:1. A paddlewheel apparatus (101)for a raceway pond(100), said paddlewheel apparatus (101)comprising:
a plurality of elongated paddles (P1 to P6)coupled to a rotatable disc (D)such that each elongated paddle is obliquely disposed on said rotatable disc(D)and extendingradially outwards from the periphery of said rotatable disc(D),
wherein, each elongated paddle is operatively laterally bent (L)at a predefined distance(a)along its length at an angle of around 45 degree (o)in the direction(A) of rotation of said rotatable disc(D).
2. The paddlewheel apparatus (101)as claimed in claim 1, wherein saidrotatable disc (D)is annular in shape.
3. The paddlewheel apparatus (101)as claimed in claim 1, wherein said lateral bend (L)of said each elongated paddle is adjustable with respect to the total depth (b3)of the culture in said raceway pond(100).
4. The paddlewheel apparatus(101)as claimed in claim 1, wherein said predefined distance (a)of said lateral bend (L)is directly proportional to thetotal depth (b3)of the culture in said raceway pond(100)and varies in relation to a portion (p) of said each elongated paddle immersed in the culture.
5. The paddlewheel apparatus (101)as claimed in claim 1, wherein said predefined distance (a)of said lateral bend (L)is at a length of 30% to 70% of the portion (p) of said each elongated paddle immersed in the culture.
6. The paddlewheel apparatus (101)as claimed in claim 1, wherein said predefined distance (a)of said lateral bend (L)is at around halfway mark of the portion (p) of said each elongated paddle immersed in the culture.
7. The paddlewheel apparatus (101)as claimed in claim 1, wherein a minimum ground clearance (g)is provided between a distal endof said each elongated paddle and a floor of said raceway pond(100).
8. The paddlewheel apparatus (101)as claimed in claim 1, wherein said each elongated paddle is at least partially submerged in the culture in said raceway pond(100).
9. The paddlewheel apparatus (101)as claimed in claim 1, wherein a portion of said each elongated paddle that needs to be submerged in the culture is calculated using computational fluid dynamics simulations.