ABSTRACT
In this paper, the effects of useful energy ratio, some exergetic indicators on the performance of a thin-layer solar drying system by using the experimental data in the literature for white mulberry, were investigated. In addition, the forced convection heat transfer parameters of white mulberry were evaluated.
The results demonstrated that the energy utilization ratio, exergetic efficiency and waste exergy ratio varied between 7.142–47.142% and 18.33–98.62%, and 1.37–81.66%, respectively. The exergetic sustainability indexes and environmental impact factors changed from 0.224 to 8.079 and 0.0139 to 4.453, respectively. The values of improvement potential ranged from 0 to 0.053 kW. The convective heat transfer coefficient values for white mulberry were between 18.947 and 19.040 W/m2°C.
Nomenclature
cp | = | specific heat of drying air (kJ/kg K) |
Cv | = | specific heat of humid air (J/kg°C) |
EE | = | exergetic efficiency |
EUR | = | energy utilization ratio |
EIF | = | environmental impact factor |
ESI | = | exergetic sustainability index |
Ex | = | exergy (kW) |
h | = | enthalpy (kJ/kg) |
hc | = | convective heat transfer coefficient (W/m2°C) |
IP | = | improvement potential (kW) |
Kv | = | thermal conductivity of humid air (W/m°C) |
L | = | length (m) |
ṁ | = | mass flow rate (kg/s) |
Nu | = | Nusselt number |
Pr | = | Prandtl number |
Re | = | Reynolds number |
V | = | velocity (m/s) |
t | = | time (s) |
T | = | temperature (°C) |
Ts | = | product surface temperature (°C) |
Te | = | exit air temperature (°C) |
Ti | = | average of product and humid air temperature (°C) |
WER | = | waste exergy ratio |
Greek Letters
η | = | efficiency |
μv | = | dynamic viscosity of humid air (kg/m) |
ρv | = | density of humid air (kg/m3) |
Subscripts
c | = | collector |
d | = | destruction |
da | = | drying air |
dci | = | drying cabinet inlet |
dco | = | drying cabinet outlet |
eus | = | exergy used |
ex | = | exergy, exergetic |
f | = | fan |
i,in | = | inlet |
L | = | loss |
o | = | outlet |
sol | = | solar |
Acknowledgments
Authors thank Firat University Research Foundation (FUBAP) for financial support under project number 943.
Additional information
Notes on contributors
Ebru Kavak Akpinar
Ebru Kavak Akpinar has been working as proffessor in Mechanical Engineering Department at Firat University, Elazig-Turkey, since 2011. She received her PhD in Mechanical Engineering, Firat University, Institute of Science and Technology in 2002. She is mainly interested in thermodynamics, heat and mass transfer, analysis and modeling energy systems, solar, wind energy applications.