Observation of the drying process in secondary school kos - PowerPoint PPT Presentation

Observation of the drying process in secondary school Ákos Szeidemann, Áron Bodor, Marcell Juhász Teaching Physics Innovatively New Learning Environm ents and Methods in Physics Education 17-19 August 20 15

Extra curricular activity The cabinet The collector Line schematic diagram of the collector The solar dryer

Extra curricular activity The efficiency of the collector: P coll η = P solarrad     P = c ρ v A Δ T c air - specific heat of air coll air air ρ air – density of air v - velocity of flowing air A - cross section of holes Δ T - temperature difference

Extra curricular activity The „efficiency” of the dryer:  L m water evap  η = 0.3% dryer S A Δ t solar rad coll L water - evaporation heat of water m evapor - mass of evaporated water P solarrad - the solar radiation A coll - the useful surface of collector Δ t - the time needed

Measurements with the electric dryer „Efficiency” of the electric dryer: Δ m  kg 2 10  evap   L 6 J/kg 2,26 10 water Δ t s 3600   η = = = 100 100 2,5 % el dryer . P W 250 electric Electric Solar

Measurements with the electric dryer Δ E flowingair Δ t Air warming efficiency of the electric dryer: η heat = P electric Determination of flowing air’s amount   Δ E = C n Δ T flowingair p, air flowingair flowingair W 100  η heat = = 100 40 W 250

The Process of drying

The Process of drying The set-up for measurements

The Process of drying M − M e m  M ( ) = water MR = % 100 m M i − M e sample Moisture content on dry basis (%) Moisture ratio E.K. Akpinar, Y. Bicer, F. Cetinkaya: Modelling of thin layer drying of parsley leaves in a convective dryer and under open sun, J. of Food Engineering 75 (2006) 308-315

The Process of drying        n MR t = kt exp Linearization            MR = n k + n t ln ln ln ln  y = a + b x

Results

A physical picture: Evaporation Drying Evaporation Sugar-water compound Fruit (80 % m/m water) * * Evaporation of the compound is observed in an electric dryer, same circumstances as before

A physical picture: Evaporation Drying Evaporation Pentane-parrafin oil compound (80 % m/m parrafin oil)* * Evaporation of the compound is observed on open air

A physical picture: Evaporation Estimation, similarity, SIMPLIFICATION Drying Evaporation (diffusion + evaporation) Description for the measured range of Theory, experiments time Mathematical model(s)

Application in classrooms ELECTRIC DRYER FRUITS/SUG-WAT* + KITCHEN BALANCE TIME OPEN AIR C-HEXANE&PARRAFIN + ANALYTIC BALANCE OK * Sugar-water compound

Application in classrooms

Dice - model

Dice - model

Thank you for your attention!

References, papers  [1] Szeidemann Á., Környezeti fizika a középiskolában, a napenergiás aszaló , Juhász A. és Tél T. (szerk.), Fizikatanítás tartalmasan és érdekesen konferenciakötet, ELTE TTK (2009), ISBN 978-963-284-150-2, pp. 209-214.  [2] Szeidemann Á., Teaching facilities of solar energy in secondary schools , Physics Competitions (2011), Vol. 13, Nr. 1., pp. 9- 14.  [3] Szeidemann Á., Az energiafogalom szintézise a napenergiás aszalóval , Tasnádi P. (szerk.), Természettudomány tanítása korszer ű en és vonzóan, ELTE TTK (2011), ISBN 978-963-284- 224-0, pp. 220-225.  [4] Szeidemann Á. és Beck R., A ciklonok szemléletes tanítása középiskolában , Tasnádi P. (szerk.), Természettudomány tanítása korszer ű en és vonzóan, ELTE TTK (2011), ISBN 978-963-284- 224-0, pp. 632-637.  [5] Szeidemann Ákos, Fizika és földrajz határán – Tanítható- e a Coriolis-er ő ? , Fizikai Szemle (2013), LXIII. Évf., 10. sz. pp. 352-357.