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

Observation

• f 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

The efficiency of the collector:

cair - specific heat of air ρair – density of air v - velocity of flowing air A - cross section of holes ΔT - temperature difference

Extra curricular activity

η = Pcoll Psolarrad

ΔT A v ρ c = P

air air coll

   

The „efficiency” of the dryer:

Lwater - evaporation heat of water mevapor - mass of evaporated water Δ t - the time needed Psolarrad - the solar radiation Acoll - the useful surface of collector

Extra curricular activity

0.3%   Δt A S m L = η

coll rad solar evap water dryer

Measurements with the electric dryer

„Efficiency” of the electric dryer:

Electric Solar

% 2,5 100 250 3600 10 10 2,26 100

2 6 .

= W s kg J/kg = P Δt Δm L = η

electric evap water dryer el

    



Determination of flowing air’s amount

Measurements with the electric dryer

Air warming efficiency of the electric dryer: ηheat=

ΔEflowingair Δt Pelectric

flowingair flowingair air p, flowingair

ΔT n C = ΔE  

40 100 250 100 = W W = ηheat 

The Process of drying

The Process of drying

The set-up for measurements

100 % 

sample water

m m = ) ( M MR = M− M e M i− M e

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

Moisture content on dry basis (%) Moisture ratio

The Process of drying

   

 

n

kt = t MR  exp

 

 

   

t n + k n = MR ln ln ln ln   

x b + a = y 

Linearization

Results

A physical picture:

Evaporation

Drying Evaporation Fruit Sugar-water compound (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

Drying (diffusion + evaporation) Mathematical model(s) Evaporation

Theory, experiments Estimation, similarity, SIMPLIFICATION Description for the measured range of time

Application in classrooms

ELECTRIC DRYER FRUITS/SUG-WAT* + KITCHEN BALANCE TIME

* Sugar-water compound

OPEN AIR C-HEXANE&PARRAFIN + ANALYTIC BALANCE OK

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 korszerűen 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 korszerűen 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-erő?, Fizikai Szemle (2013), LXIII. Évf., 10. sz. pp. 352-357.