Experiment Study & Analysis of Solar Air Heater With Offset Fin.

Transcription

1 Experiment Study & Analysis of Solar Air Heater With Offset Fin. Nishant Sharma 1, Dr. Bhupendra Gupta 2* 1 Student, Master of Engineering, Heat Power, JEC, Jabalpur 2* Assistant Professor, Jabalpur Engineering College, Jabalpur, India Abstract :- Many years since,the enhancement of the thermal heat transfer in different systems, where the air is used, had drawn the attention of many searchers.the air with its unfavorable thermo physical properties presents a low heat transfer coefficient. In spite of these mediocre characteristics. the air is widely used as fluid of heat transfer because other factors have been taken into account. These factors have the advantage of more large consideration than the thermal performances, which and oneself relegated to the background.when the air systems are employed for the needs of heating or drying, inexpensive materials are used and one does not fear the inopportune leaks of circuit like that encountered by using the water. Key word; - Air inlet,air outlet, Aluminum plate,temperature, offset fin 1.Introduction- Various designs with different shapes and dimensions of the air flow passage in plate type of solar air collectors were tested.the effect of the flow passage geometry on the heat convective coefficients between the air stream and the plate were particularly examined.a slit and expanded aluminum foil matrices were used to increase the thermal performance. Blackened wire screen matrices was employed that permits to improve the thermal performances. An experimental investigation. was conducted on two matrices constituted by randomly stacking blackened wire screens. Wire matrices were used in solar collectors to give higher thermal performance in comparison to the flat plate collector. Other materials with different character and forms were used,various materials were tested. the hollow spheres, the crushed glass. In these cases,the tests showed that the thermal performances were improved in comparison of those of flat plate collectors. The thermal performances of solar air collectors had been evaluated theoretically and experimentally, where the channel ducts of solar collector were filled with semi-transparent material. From the analysis of test results it was observed that the collectors filled with semi-transparent balls and tubes give high efficiencies than the flat plate collector.these materials were used for the heat collection and a storage of some part of heat in depth. The tests of performance on the solar air collectors which were lined with aluminum chips. 2. Experimental procedures The solar air collector is constructed so that it can be dismantled and certain elements "transparent cover, the absorber-plate and the back of duct# can be changed in order to vary the collector configuration, This avoids making several collectors with only a flate plate and four rectangular offset plate fins absorbers are designed. The exhaust fan is fixed at the outlet collector, a dimmer switch permit to vary the mass flow rate of the air, The nature of flow regime was studied in wind tunnel and showed the successive boundary layers that alternates after each interruption. The chest of solar air collector is wooden made it presents a well insulation at the back and lateral sides. This insulation is realized by a polystyrene sheet of 3 cm thick sandwiched between back and rear wooden plate, In the present work only the absorber and the transparent cover are changed they permit to show their effect on the thermal performance. ISSN: Page 159

2 Two types of transparent covers are experimented which are alveolar polycarbonate sheets with double and triple walls, Four offset plate fins absorbers are tested they present fins with different length and interruption, The number of tested collectors then attains height. 3. Results and discussion- Table.1.Offset fin are 10mm, Airflow rate 1 10: : : : :00 48 Figure.1. Control device 6 15: :00 41 Temperature at outlet =50 C = (50-30)/30 =66.66% Figure.2. Blower Figure.3. Experimental setup Figure.4. Offset fin are 10mm, Airflow rate ISSN: Page 160

3 Table.2.Offset fin are 10mm, Airflow rate are 3 M 3 / Minute Table.3.Offset fin are 20mm, Airflow rate 1 10: : : : : : : : : : : :00 49 Temperature at outlet =52 C = (52-30)/30 =73.33% Temperature at outlet =55 C = (55-30)/30 =83.33% Figure.5. Offset fin are 10mm, Airflow rate are 3 M 3 / Minute Figure.6. Offset fin are 20mm, Airflow rate ISSN: Page 161

4 Table.4.Offset fin are 20mm, Airflow rate 1 10: : : : : : :00 44 Table.5.Offset fin are 30mm, Airflow rate 1 10: : : : : :00 43 Temperature at outlet =57 C ή= ( Temperature at outlet -Temperature at inlet) = (57-30)/30 =90.00% Temperature at outlet =51 C = (51-30)/30 =70.00% Figure.7. Offset fin are 20mm, Airflow rate Figure.8. Offset fin are 30mm, Airflow rate ISSN: Page 162

5 Table.6.Offset fin are 30mm, Airflow rate 1 10: : : : : : :00 43 Temperature at outlet =53 C = (53-30)/30 =76.66% 4.Conclusion: The air stream reduces sensibly the temperature of the absorber and in same time the heat losses are reduced. With the offset fin collector the double glazing gives lower thermal performance than the triple glazing this is due to the heat losses towards the surroundings. Then with the triple glazing, the amount of intercepted radiation transmitted to the absorber was diminished but the global heat losses are further reduced. The double glazing transmits more radiation than the triple glazing cover but the heat losses remains important. Using of Offset fin are 20mm, Airflow rate. Find out the Efficiency are 90.00% Reference [1] Freeman TL, Mitchell JW, Audit TE. Performance of combined solar heat pump systems. Solar Energy 1979;22(2): [2] O Dell MP, Mitchell JW, Beckman WA. Design method and performance of heat pumps with refrigerant-filled solar collectors. Trans ASME, J Sol Energy Eng 1984;106(2): [3] Sakai I, Takagi M, Terakawa K, Ohue J. Solar space heating and cooling with bi-heat source heat pump and hot water supply system. Solar Energy 1976;18(6): [4] Hatheway FM, Converse AO. Economic comparison of solarassisted heat pumps. Solar Energy 1981;27(6): [5] Solar-assisted heat pump for the heating and cooling of buildings. Six month technical report, General electric company corporate research and development. Schenectady: New York 12301; May [6] Bessler WF, Hwang BC. Solar assisted heat pumps for residential use. ASHRAE J 1980;22(9): [7] Cottingham JG. Heat pump design: Cost-effectiveness in the collection, storage and distribution of solar energy. ASHRAE J 1979(4):35 8. [8] MacArthur JW, Palm WJ, Lessmann RC. Performance analysis and cost optimization of a solar-assisted heat pump system. Solar Energy 1978;21(1):1 9. Figure.9. Offset fin are 30mm, Airflow rate ISSN: Page 163