Energy is an important source in the world of economic, social and industrial development of any nation. During the last several decades, energy demand of the world has been increasing continuously at a large rate due to increase in population, industrialization, transportation etc. Alternatives to this, solar energy is an important renewable energy resource that has the potential of fulfilling all our energy needs. Some effective applications of solar energy are solar water heating, solar crop drying, solar power generation etc. The simplest method to use solar radiation is to change it into thermal energy for heating applications by the use of solar collectors. Solar Air Dryer, because of their inherent simplicity are cheap and are used for many domestic and commercial purpose like space heating, crop drying etc. In this paper the purpose of the CFD flow study is to configuration, test and enhance the flow-conditioning devices, as appropriate, to guide the gas flow through the duct. The CFD code FLUENT VERSION 14.5 is utilized to examine 2D numerical reenactment of the Heat exchange, Velocity and Temperature. The CFD modeling involves numerical solutions of the conservation equations for mass, momentum and energy. The three conditions are utilized with the accompanying presumptions; (a) The wind current is unfaltering, completely created, turbulent and two dimensional. (b) Incompressible liquid and flow. (c) The conduit divider, safeguard plate and unpleasantness material are homogeneous and isotropic.
The utilisation of solar energy has achieved a noteworthy edge. The nonstop research for an electric power source because of the apparent shortage of fuel fossils is its main cause. It had turned out to be much more famous as the cost of fossil fuel keeps on rising. Of all the inexhaustible well springs of enrgy accessible, sun orented vitality is the most plenteous one and is accessible in both immediate and in addition backhanded structures. Sun orinted vitalty applications were partitioned for the most part into two classes: the first is the immediate change to power utilizing sun oriented cells (electrical applications). The second is the warm applications. The last incorporate sun powered warmng, sunlight based cooling and drying, sun orinted cooking, sun based refining, sun based heaters, sun based water warming, sun powered air warmng, and so forth. Nitty gritty portrayal, essentials and past work performed on sun powered dryers and sunlight based air radiators, as the crucial components for the aberrant and blended methads of sun powerd dryers.
Conventional techniques for drying is to spread the foodstuffs to put the foodstuffs in the sun in the outside. This technique, called sun drying, is successful for little measures of sustenance. The territory required for sun drying grows with nourishment amount and since the sustenance is set in the outdoors, it is effortlessly polluted. Along these lines, one noteworthy motivation behind why sun drying isn’t effortlessly performed with bigger amounts of sustenance is that the observing and outlines turns out to be progressively more troublesome with expanding nourishment amounts.
As opposed to sun drying, where the meat is dried particularly to the sun, the sun fueled drying system uses underhanded sun based radiation. The standard of the sun based drying technique is to assemble sun controlled imperatives by warming up the air volume in sun based specialists and direct the hot air from the gatherer to a joined alcove, the meat drying chamber. Here the things to be dried are laid out.
Sun based air heater (Solar air dryer) is a kind of vitality authority in which the vitality from the sun, used to warm air. Sun powered air warming is a sustainable power source warming innovation used to dry the farming items adequately and effectively. A basic sunlight based air authority comprises of a safeguard material, once in a while having a specific surface, to catch radiation from the sun and exchanges this warm vitality to air through conduction warm exchange. This warmed air is then ducted to the items, for example, chilies, grapes and so forth.
The essential capacity of the plate is to ingest however much as could be expected of the radiation coming to plate, free as meager warmth as conceivable upward to the air and descending through the back of the compartment
A level board or plate, redirector, or comparative gadget set in streaming air frameworks to make more uniform stream speeds ingest more vitality and to occupy the air. These confuses give more zone of contact by redirecting or avoiding the wind stream.
One of the fundamental parts of the authority is the glass cover. Glass effortlessly transmits short-wave radiation, which implies that it postures little impedance to approaching sunlight based vitality. Once the sun’s vitality has gone through the glass windows and has consumed by some material inside, the warmth won’t be reradiated back outside. Glass in this manner demonstrations like warmth trap.
The duct is made up of PVC, the inlet duct is present at the bottom of the collector because of the fact that air enters from lower side at low temperature. Whereas the outlet is present at the top as cold air comes from lower side to replace the hotter air.
The collector was upheld and fitted with the assistance of a casing made up of iron. The casing was structured with four legs, two of same length and other two of same distinctive height.
Computational Fluid Dynamics or CFD as it is prevalently known, is utilized to produce stream reenactments with the assistance of PCs. CFD includes the arrangement of the representing laws of liquid elements numerically. The perplexing arrangements of halfway differential conditions are illuminated on in geometrical area separated into little volumes, regularly known as a work (or matrix).
CFD has empowered us to comprehend the world in new ways. We would now be able to perceive what it resembles to be in a heater, show how blood moves through our courses and veins and even make virtual universes. CFD empowers examiners to recreate and comprehend liquid streams without the assistance of instruments for estimating different stream factors at wanted areas
Computational Fluid Dynamics gives a subjective forecast of liquid streams by methods for
Numerical reenactments of liquid stream (will) empower
The target motivation behind the CFD stream contemplate is to configuration, test and to enhance the flow conditioning device , as fitting, to control the gas move through the channel. The CFD code FLUENT VERSION 14.5 is used to look at 2D numerical reenactment of the Heat exchange, Temperature and Velocity. The CFD demonstrating includes numerical arrangements of the conservation conditions for mass, force and energy.
The three conditions are utilized with the accompanying presumptions;
(a) The breeze current is unflinching, totally made, turbulent and two dimensional.
(b) Incompressible fluid and stream.
(c) The conductor divider, shield plate and obnoxiousness material are homogeneous and isotropic.
Future scope of solar dryer
Future scenario of CFD in food processing industry
The benifit of CFD applications in food industry will definetly bring boom in food industries in future. It also helps to understand the physics of a food processing operation and thus help in the optimisation and design of existing and new processing equipments, easier & less expensive the CFD technique are.
In future coming years, food engineering need not to worry about the non enginering issue, like mesh structure, cell shapes because of the new development of completelly automated mesh. Hence all this advance development will contribute to CFD in becoming a powerful tool in engineering department. So in future, more and more broad and rapid adoption in the use of CFD in the food industry will definetly take place as a result in CFD advancement.
Working of Solar Dryer
Formulation of CFD Model
Result & Discussion
Solar Air Dryer
Food items have been dried by the sun. The intention is either to protect them for later use, similar to the case with sustenance; or as a necessary piece of the creation procedure, as with timber, tobacco and washing. In industrialized areas and segments, outdoors drying has now been to a great extent supplanted by automated dryers, with boilers to warm approaching air, and fans to constrain it through at a high rate.
Motorized drying is speedier than coordinate sun drying, utilizes less land and gives better quality sustenance things. Be that as it may, the hardware is too exorbitant and furthermore expected power to work. Whereas, “Sunlight based Air Drying” comprises more powerful drying as it utilize the sun vitality for it, likewise it have bring down working expense than motorized dryers.
The framework comprises of level plate authority, drying chamber/cupboard and a stack. There are three astounds joined to the safeguard plate in crisscross way so it builds the turbulence in the level plate authority which in turn helps in the ascent of temperature of air and bigger territory of contact amongst air and the safeguard plate.
The general principle utilized in a sunlight based dryer are:
Direct sun oriented dryers: In these dryers, the material to be dried is put in a straightforward walled in area of glass or straightforward plastic. The sun warms the material to be dried, and warm additionally develops inside the walled in area due to the ‘nursery impact.’ The drier chamber is typically painted dark to ingest the most extreme measure of warmth.
Indirect sun powered dryers: In these dryers, the sun does not act straightforwardly on the material to be dried in this manner making them helpful in the readiness of those harvests whose vitamin substance can be devastated by daylight. The items are dried by hot air warmed somewhere else by the sun.
Blended mode dryers: In these dryers, the joined activity of the sunlight based radiation occurrence on the material to be dried and the air preheated in sun oriented gatherer gives the warmth required to the drying task.
Cross breed sunlight based dryer: In these dryers, in spite of the fact that the sun is utilized to dry items, different advances are additionally used to cause air development in the dryer.
At the point when adapted air can not be provided straight forwardly from the cooling hardware to the spaces, at that point Ducts (pipes) are introduced. The duct framework pass on the molded air from the aerating and cooling gear to the best possible air dispersion point. Ducts are generally produced using galvanized iron sheet metal, aluminium sheet metal or black steel. The most usually utilized channel is galvanized sheet metal, on the grounds that the zinc covering of this metal averts rusting and evades the cost of painting. The aluminum is utilized due to its lighter weight and protection from dampness.
Working in CFD is finished by recording the CFD codes. CFD codes are organized around the numerical calculations that can be handle liquid issues. Keeping in mind the end goal to give simple access to their unraveling power all business CFD bundles incorporate modern UIs input issue parameters and to look at the outcomes. Consequently all codes contain three primary components:
The geometry and physical limits of the issue can be characterized utilizing PC supported plan (CAD). From that point, information can be reasonably prepared (tidied up) and the liquid volume (or liquid space) is separated.
The volume involved by the liquid is partitioned into discrete cells. The mesh might be variant or invariant, organized or unstructured, comprising of a blend of hexahedral, tetrahedral, kaleidoscopic, pyramidal or polyhedral components.
The physical demonstrating is characterized – for instance, the conditions of smooth movement + enthalpy + radiation + species protection.
Boundary conditions are characterized. This includes determining the liquid conduct and properties at all jumping surfaces of the liquid area. For transient issues, the underlying conditions are additionally characterized.
The recreation is begun and the conditions are comprehended iteratively as a consistent state or transient.
Finally a post processor is utilized for the examination and representation of the subsequent arrangement.
In view of Control Volume Method, 3-D examination of air in a stationary Solar Air Dryer duct loaded with solid material is done on fluent software.
The Finite Volume Method (FVM) is a typical approach utilized as a part of CFD codes, as it has favorable position in memory utilization and arrangement speed, particularly for extensive issues, high Reynolds number turbulent streams, and source term commanded streams.
In the Control Volume Method, the administering partial differential conditions ( the mass and energy protection conditions, and the turbulence conditions) are recast in a preservationist shape, and after that comprehended over discrete control volumes. This discretization ensures the preservation of motions through a specific control volume. The finite volume condition yields overseeing condition in the form ,
where Q is the vector of preserved factors, F is the vector of transitions, V is the volume of the control volume component, and A is the area of the control volume component
In view of Control Volume Method, 3-D examination of air in a stationary Solar Air Dryer duct loaded with solid material is done on fluent software.
Dimension of duct:
Length of duct: Vertical=790mm
Angle of inclination= 7 degrees
Dimension of Tray:
Dimension of hole:
Diameter of hole = 30mm
Now from the above study and examination using CFD code FLUENT VERSION 14.5 for the 2D numerical reenactment of the Heat exchange, Velocity and Temperature. We find from the above examination, the flow through solar dryer duct with tray hole.
Temperature -308 Kelvin
Velocity Of Air- 1 m/s
Absorbtivity = 0.8
Module Used :
Energy & Solar Radiation Module
Heat exchange is likewise builds due to increment in temperature. Trapezoidal rib is for the most part in charge of increasing temperature.
There is almost certainly that a noteworthy focus of CFD investigation of solar air dryer is to improve the outline procedure that arrangements with the heat exchange and liquid flow.
The simulation also tells that there is no need of very long exposure to direct sun rays is required to gain enough high temperature for preservation.
An effort has been made to do CFD based investigation utilizing FLUENT 6.2 to liquid flow and heat exchange qualities of solar air dryer having roughened duct pipe provided with the artifacial unpleasantness. Joined impact of turbulence and reattachment of liquid which was thought to be dependable in incresing heat exchange rate.
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