IJRMET Vol. 6, IssuE 2, May - ocT 2016

w w w . i j r m e t . c o m InternatIonal Journal of research In MechanIcal engIneerIng & technology 135

Issn : 2249-5762 (online) | Issn : 2249-5770 (Print)

Power Generation From Solar Energy Through Thermo-Electric Materials

1Shaik Nayeem, 2Mallela Ravi Kiran, 3Eppala Rama Krishna Reddy1,2,3Dept. of Mechanical Engg., Lakireddy Bali Reddy College of Engg., Mylavaram, AP, India

AbstractIn recent years, an increasing concern of environmental issues of emissions, in particular global warming and the limitations of energy resources has resulted in extensive research into novel technologies of generating electrical power. Thermoelectric power generators have emerged as a promising alternative green technology due to their distinct advantages. Their typical efficiencies are around 5-8%. Older Seebeck-based devices used bimetallic junctions and were bulky while more recent devices use semiconductor p-n junctions made from bismuth telluride (Bi2Te3), lead telluride (PbTe), calcium manganese oxide, or combinations thereof, depending on temperature.These are solid state devices and unlike dynamos have no moving parts, with the occasional exception of a fan or pump. It is proposed to develop thermo electric power generator which use solar energy as a alternative green source to develop power. Present work, solar radiation is concentrated on the copper envelop to which thermo-electric materials are attached from inner side. Cold junction is created by providing ordinary tap water by creating inner envelop with copper material. Current and Voltage readings are taken by Multi-meter at the terminal connections of thermo-electric materials.

KeywordsPower Generation, Solar Energy, Thermo-Electric Materials

I. Introduction

A. Thermo-Electric Materials for Power GenerationA thermoelectric power generator is a solid state device that provides direct energy conversion from thermal energy (heat) due to a temperature gradient into electrical energy based on “Seebeck effect”.

1. Seebeck EffectWhen a temperature difference is established between the hot and cold junctions of two dissimilar materials (metals or semiconductors) a voltage is generated, i.e., Seebeck voltage. The fig1 shows the thermoelectric power cycle, with charge carriers (electrons) serving as the working fluid, follows the fundamental laws of thermodynamics and intimately resembles the power cycle of a conventional heat engine.

2. Thermoelectric Power Generators Offer Several Distinct Advantages Over Other TechnologiesThey are extremely reliable (typically exceed 100,000 hours of steady-state operation) and silent in operation since they have no mechanical moving parts and require considerably less maintenance. They are simple, compact and safe. They have very small size and virtually weightless. They are capable of operating at elevated temperatures. They are suited for small-scale and remote applications typical of rural power supply, where there is limited or no electricity. They are environmentally friendly. They are not position-dependent and they are flexible power sources.

Fig. 1: Schematic Diagram Showing the Basic Concept of a Simple Thermoelectric Power Generator Operating Based on Seebeck Effect

B. Solar EnergyVast quantities of solar heat are discharged into the earth’s environment much of it at temperatures which are too low to recover using conventional electrical power generators. Thermoelectric power generation (also known as thermoelectricity) offers a promising technology in the direct conversion of thermal energy, such as solar into electrical power. Since the conversion efficiency of a module is comparatively low, thermoelectric generation using solar energy is an ideal application. In this case, the operating cost is negligible compared to the module cost because the energy input (fuel) cost is free. The earth’s sun makes more energy in one second than the amount six billion nuclear power plants would produce in a year. The sun is also the source of all energy supplies, except for nuclear and geothermal energy.Heat flux from the sun is 1395 W/m2

C. Solar radiation is Concentrated on Single Area or Point and it is used as Hot Junction in Producing Power by Thermo-Electric MaterialsFig. 2 shows how the thermo plates are connected to hot junction and cold junction.

Fig. 3 shows heat flow from hot junction( solar radiation concentration) to other junction.

IJRMET Vol. 6, IssuE 2, May - ocT 2016 Issn : 2249-5762 (online) | Issn : 2249-5770 (Print)

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Fig. 2: Solar Thermo-Electric Power Generation

Fig. 3: Schematic diagram of Hot and Cold Junction in Thermo-Electric Materials

II. Experimental SetupExperiment setup consist of three steps as follows:Step 1: Preparation of Hollow Hemispherical concentratorStep 2: Preparation of Copper EnvelopsStep 3: Combining the Hollow Hemispherical concentrator and copper envelops

A. Step 1: Hollow Hemispherical Solar Radiation ConcentratorHollow Hemispherical concentrator shown in fig. 4 made of quartz glass used to focus the solar radiation on center point / concentrated point.

Hollow Hemispherical concentrator are constructed by shaping the thin rods into number of rings of diameters ranging from 1 m to 0.15 m. These rings are arranged into hemispherical shape by connecting curved shape rods. A thin polymer membrane is attached to this hemispherical arrangement. 5cm x 5cm of number of quartz glass are attached to this polymer membrane with adhesive.

Fig. 4: Solar Radiation Concentrated Point

1. Sun Tracking SystemDue to sun tracking system it can absorb maximum possible radiation at different elevation as shown in fig. 5. Sun radiation is varying from time to time, day to day, month to month. If the radiation concentrated on hemispherical concentrator varies day, then power production from the equipment will vary. So to maintain constant power production from the equipment without continuous variation, a sun tracking system is used. Due to the sun tracking system the equipment is aligned toward sun. Sun tracking system is made by creating holes on the hemispherical circular plate.

Fig. 5: Sun Tracking System

2. Thermo-Electric MaterialFig.6 shows the Thermo-Electric materials are the driving component in thermo-electric power generation. Fig. 7 shows the hot side and cold side of the thermo-electric material. Total 6 thermo-electric materials are used in the present experiment as shown in fig. 8.TEC1-12706 type of thermo-electric module selected.Area of TEC1-12706 = 4cm x 4cm.Thickness of TEC1-12706 = 2 mm

IJRMET Vol. 6, IssuE 2, May - ocT 2016

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Fig. 6: Thermo-electric Material

Fig. 7: Thermo-electric Material Hot and Cold Junction Sides

Fig. 8: 6-thermo-electric Materials

B. Step 2: Preparation of Copper EnvelopsCopper outer envelop for Hot junction:Copper outer envelop is prepared in rectangular shape with the help of gas-welding, copper outer envelop front view and top view are shown in the fig. 9. Copper outer envelop dimensions are Height = 5.6 cm ,Width = 5.9 cm and Perimeter =22 cm.

Fig. 9: Copper Outer Envelop Top View and Front View

1. Thermal Properties of CopperThermal conductivity K = 386W/(m.k), Specific Heat C = 383J/(kg.k), Density = 8954 Kg/ m3

Thermal Diffusivity = 112.34 x 10-6 m2/sec

2. Copper inner envelop for Cold junction:Copper inner envelop are prepared, similar to outer envelop. The inner envelop dimensions are:Height = 4.8cmWidth = 5.1cmPerimeter = 19.8cm

III. Experimental ProcedureSix Thermo – Electric materials are attached to the outer copper envelop, the copper outer envelop is working as the hot junction for the thermo-electric module because solar radiation is concentrated on it. Copper inner envelop is placed inside the Copper outer envelop such that other side of thermo-electric module is makes contact with it. A tube is connected to the copper inner envelop , for the water flow, which maintains the copper inner envelop in lower temperature. Tube is connected to the ordinary tap water. So that the inner envelop acting as a cold junction. The total arrangement is placed in the concentrated point with the help of binding wires. The volume flow rate of the tap water flowing through the copper inner envelop is calculated by collecting water in the 1000ml beaker with respect to time. The temperature of atmosphere is measured by thermometer. The temperature at the concentrated point (i.e on copper outer envelop ) is measured by thermometer by making contact with the copper outer envelop. All six thermoelectric module red wires are joined and it is considered as a one terminal and all black wires of six thermo electric modules are joined and it is considered as a second terminal. These two terminals are connected to multimeter. The voltage and current readings are taken from the multimeter. The product of current and voltage is called power, so power is obtain by these values.

Fig. 9: The Arrangement of Copper Outer Envelop and Thermoelectric Modules and Copper Inner Envelop.

Fig. 10: Connection of Copper Outer Envelop and Tube for Water Supply

IJRMET Vol. 6, IssuE 2, May - ocT 2016 Issn : 2249-5762 (online) | Issn : 2249-5770 (Print)

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Fig. 11: Solar Concentrator With Thermoelectric Modules in Between Copper Envelops

IV. Readings and CalculationExperiment is conducted on 1:43 PM ; 13/07/2016 .Volume flow rate is measured by using 1000 ml beaker and stop watch.Volume Flow rate Q = volume / TimeVolume =1000ml, Time = 1.42 secQ = 1000/1.42Q= 704.2253521 m3/sec

A. Temperatures Before Equipment Exposed to Sun Light:Temperature of copper outer and inner envelop = 35oCTemperature of water at the outlet of copper inner envelop= 32 0C

B. Temperature, Current and Voltage Readings After Equipment Exposed to Sun Light:Temperature of copper outer and inner envelop = 50oC.Temperature water at the outlet of copper inner envelop= 36 0C.Voltage from the Multi-meter V = 2.5 volts.Current from the Multi-meter I = 064 amps.

V. ConclusionThe present investigation aimed to generate power by using solar energy through thermo- electric modules. The analysis was carried out by fabricating copper envelops and creating concentrated heat zone by Hollow Hemispherical concentrator, cold zone by ordinary water supply. Power is generated due to temperature difference exits between two junctions of thermo-electric modules.

The out put voltage from the terminals of thermo-electric materials V=2.5 volts and current I =0.64 amps

The total power produced from the six thermo-electric modules is P= 1.6 Watts

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SHAIK NAYEEM has under-graduated in Mechanical Engineering in Rajiv Ghandi University of Knowledge Technology in 2014 and after that worked as Asst.Proffessor in Gudlavalleru Engineering College.Now pursuing M.tech from Lakireddy BaliReddy College of Engineering. His areas of interest are Vibration, Heat Transfer, Thermal Engg., and Solar Energy.

MALLELA RAVI KIRAN has under-graduated in Mechanical Engineering in 2014 in 2014. Now pursuing M.tech from Lakireddy BaliReddy College of Engineering. His areas of interest are Internal Combustion Engines, Power Plant Engineering, Thermal Engg., and Solar Energy.

IJRMET Vol. 6, IssuE 2, May - ocT 2016

w w w . i j r m e t . c o m InternatIonal Journal of research In MechanIcal engIneerIng & technology 139

Issn : 2249-5762 (online) | Issn : 2249-5770 (Print)

EPPALA RAMA KRISHNA REDDY has under- graduated in Mechanical Engineering in 2014. Now pursuing M.tech from Lakireddy BaliReddy College of Engineering. His areas of interest are Internal Combustion Engines, Fluid Mechanics, Thermo-dynamics and Solar Energy.