QUANTIFYING SOLAR ENERGY

Transcription

1 QUANTIFYING SOLAR ENERGY Recommendations for implementation in the course Author: address: Institution: Philipp Weihs BOKU Important considerations Very high temperatures occur during this experiment and therefore constant supervision is required. Equipment stand needed to conduct the experiment 1

2 Parts of the trial Equipment stand with Fresnel lens Casing with built-in test tube and heating plate Stopwatch Electrical thermometer with bulb sensor Plate with 4 bore holes for adjusting Set-up plate with mid-line separation marking 2

3 Form to document the trial Injection syringe Test tube 3

4 Conducting the trial At the beginning of the trial the adjustment plate should be set up in front of the Fresnel lens on the equipment stand. Fill the test tube with 8 to 10ml-distilled water using the injection syringe. Record the exact amount on the form. Place the test tube in the casing from above so that the hot plate with the blackened side can be completely seen through the casing window and sits comfortably in the lower cork ring. The height of the casing can be adjusted so that the black marking strip is in line with the upper and lower edge of the clamp. Carefully lower the thermometer into the test tube and fasten it with its holder to the casing. The electric thermometer, fastened to the base plate with Velcro, can be dismounted in order to allow viewing in an easier to read place. It is important that no tension from the thermometer cable is put on the equipment stand. The thermometer is switched on by pushing the ON/HOLD button. Fasten the stopwatch to the base plate using a magnet. This allows the watch to be easily removed. The equipment stand should be roughly positioned toward the sun and the Fresnel lens adjusted correspondingly in the sun s direction. Hoist the adjustable plate to the casing window with its slotted underside and mid-line divider to face the sun. By carefully adjusting the equipment to face the sun, the four light points (seen on the set-up plate) can all be directed to the mid-line dividing strip. Now remove the adjustable plate. Note the current temperature on the form. 4

5 At the same time as removing the adjusting plate, start the stopwatch. It is important not to bring the equipment stand out of alignment. It is recommended to record the temperature every ten seconds on the corresponding form. The trial should be discontinued as soon as the boiling point has been reached. If the water is allowed to heat up for too long it may boil over, which could result in acute burns. The fitted adjusting plate ensures that the focal point is not be positioned on flammable objects as the sun continues along its path or if the equipment stand is brought out of alignment. A piece of wood can begin to burn within seconds. Let the water stand and cool down to avoid burns. Technical information The frame is constructed out of wood and is coated with a water-soluble varnish. Size of base plate: 30 x 25cm Total height: Minimum 31 cm, Maximum 39 cm The equipment can be adjusted using the wing nuts to correspond to the height of the sun. Fresnel lens Lines per inch: 50 Size (Inch): 11.0 x 11.0 Effective size (Inch): 10.5 x 10.5 Focal length EFL (Inch): 8.20 Center thickness CT (Inch): 0.09 Tolerance of focal length (%): ±5 Tolerance Size (inch): ±0.05 Tolerance thickness (%): ±40 Transmission (%): 92 (from nm) Calculation index: nd 1.49 Operating temperature ( C): 80 (Maximum) Test tube out of silica glass Outer diameter: 15mm Length: 160mm Hot plate made of 0.5 mm thick aluminum, blackened 5

6 Protective pipe made of brushed steel Test tube holder made of cork Electrical thermometer with bulb sensor Basic accuracy: ±(1% or 1 C) Sensor type: K-Type Power supply: 1 x CR2032 Type: Mini-K Dissolution temperature: 0.1 C Dimensions (W x H x D): 43 x 78 x 20 mm Weight: 41 g Temperature range: -64 to C Conducting Mini-K Jet proof IP65 Filler type: K-Type (Ni CrNi) Temperature: -100 to C Reaction time: 0.9 s Dimensions (Ø x L): 1,5 mm x 150 mm Cable length: 2m Hook-up: Mini-K Stopwatch Timer 99 min/59 s Travel clock for demonstration Dimensions- (Ø x H) 55 mm x 18 mm Power supply- LR44 lithium battery 10 ml syringe without needle Adjustable plate with 4 settings (drilled holes), made of plywood, 315 x 295mm Distance between the drilled holes- 120 x 120mm Set-up plate with separation in the middle made of galvanized sheet metal with holding grooves on the underside. Size (W x H) 60 x 27m 6