18-10-2016, 10:22 AM
1459540069-81.Solarairconditioner.ppt (Size: 346.5 KB / Downloads: 7)
Objective: -
1. To fabricate an aluminum assembly container inside the plastic Jar/Can suitable to store food stuff inside.
2. To make a space (at any one side of the above encloses) to fit PELTIER JUNCTION APPRATUS in this with no air gap remains open.
3. To fix a small exhaust air fan at the outer surface above the PELTIER junction apparatus.
4. To fabricate & assemble a 12 V DC Power supply to provide power Source for this whole set up and battery charging (optional).
5. To Connect a change over switch for polarity reversing for cooling & heating effect inside the enclose assembly.
REQUIREMENTS
Wood and Steel Frame
PELTIER JUNCTION APPARATUS
Supply Section
Heat Sink
Bolts and Nuts
Solar panel
FAN
WORKING
For making solar based air conditioner we use PELTIER JUNCTION method. To make a space (at any one side of the above encloses) to fit PELTIER JUNCTION APPRATUS in this with no air gap remains open.
To fabricate & assemble a 12 V DC Power supply. When we connect the supply to PELTIER JUNCTION APPRATUS then we get warm up the one part of device, on other hand we get cold up the other part of device. This cold side connect to the refrigerator.
Solar air conditioner to providing 10 degree air temperature while cooling and is also heat if required with the same thermo-EMF PELTIER JUNCTION based system work on 12V battery to be charged SOLAR PANNEL.
INTRODUCTION
The Peltier–Seebeck effect, or thermoelectric effect, is the direct conversion of thermal differentials to electric voltage and vice versa. Related effects are the Thomson effect and Joule heating. The Peltier–Seebeck and Thomson effects are reversible (in fact, the Peltier and Seebeck effects are reversals of one another); Joule heating cannot be reversible under the laws of thermodynamics.
Seebeck effect
The Seebeck effect is the conversion of temperature differences directly into electricity. This effect was first discovered, accidentally, by the German physicist Thomas Johann Seebeck in 1821, who found that a voltage existed between two ends of a metal bar when a temperature difference ΔT existed in the bar.
He also discovered that a compass needle would be deflected when a closed loop was formed of two metals with a temperature difference between the junctions. This is because the metals respond differently to the temperature difference, which creates a current loop, which produces a magnetic field.
The effect is that a voltage, the thermoelectric EMF, is created in the presence of a temperature difference between two different metals or semiconductors. This causes a continuous current to flow in the conductors if they form a complete loop. The voltage created is of the order of several microvolts per degree difference.
Thermoelectric coolers are solid state heat pumps used in applications where temperature stabilization, temperature cycling, or cooling below ambient are required. There are many products using thermoelectric coolers, including CCD cameras (charge coupled device), laser diodes, microprocessors, blood analyzers and portable picnic coolers. This article discusses the theory behind the thermoelectric cooler, along with the thermal and electrical parameters involved.
NEED OF POWER SUPPLY
Perhaps all of you are aware that a ‘power supply’ is a primary requirement for the ‘Test Bench’ of a home experimenter’s mini lab. A battery eliminator can eliminate or replace the batteries of solid-state electronic equipment and the equipment thus can be operated by 230v A.C. mains instead of the batteries or dry cells. Nowadays, the use of commercial battery eliminator or power supply unit has become increasingly popular as power source for household appliances like transreceivers, record player, cassette players, digital clock etc.
DIODE
The simplest semiconductor device is made up of a sandwich of P-type semiconducting material, with contacts provided to connect the p-and n-type layers to an external circuit. This is a junction Diode. If the positive terminal of the battery is connected to the p-type material (cathode) and the negative terminal to the N-type material (Anode), a large current will flow. This is called forward current or forward biased.
If the connections are reversed, a very little current will flow. This is because under this condition, the p-type material will accept the electrons from the negative terminal of the battery and the N-type material will give up its free electrons to the battery, resulting in the state of electrical equilibrium since the N-type material has no more electrons. Thus there will be a small current to flow and the diode is called Reverse biased.
Thus the Diode allows direct current to pass only in one direction while blocking it in the other direction. Power diodes are used in concerting AC into DC. In this, current will flow freely during the first half cycle (forward biased) and practically not at all during the other half cycle (reverse biased). This makes the diode an effective rectifier, which convert ac into pulsating dc. Signal diodes are used in radio circuits for detection. Zener diodes are used in the circuit to control the voltage.
SOLAR PANEL:
A solar cell uses the photovoltaic effect to convert radiation from the sun into electrical energy. The photovoltaic effect arises when a junction between a metal and a semiconductor or two opposite polarity semiconductors is exposed to electromagnetic radiation, usually in the range near ultra violate to infrared. A forward voltage appears across the illuminated junction and power can be delivered from it to an external circuit. The p-n junction of whom the cell consists has a relatively large surface area and relatively high efficiency (10.. 15 per cent). Solar cells are fabricated mainly from silicon, gallium arsenide, selenium-cadmium sulphide, and thin-film cadmium sulphide. As part of the radiation is reflected by the surface of the cell, an anti-reflect layer is incorporated to minimize reflection. The absorption coefficient is large for short wavelengths, and smaller for longer wavelengths. The efficiency of solar cells reduces by about one half per cent for each degree centigrade rise in their body temperature, so that most cells must be suitably cooled.