Abstract:
In this study, a solar dryer
assisted with heat pump was developed and thin layer
drying of dill was carried out at air temperatures of 40, 50, and 60ºC and air velocities of
0.5, 1 and 1.5 ms
-
1
. Also, the drying rates, Specific Moisture Extraction Rate (SMER), and
energy consumption
were evaluated. Dill samples were dried from initial moisture content
of 90% to the final moisture content of 10% in 195
-
275 minutes without assisted heat
pump, and with assisted heat pump in 80
-
140 minutes. By using heat pump, the drying
rate increased wi
th increase in temperature at a given air velocity, thus, reducing the
drying time. Increase in the air velocity at a given temperature improved the drying rate.
By increasing the air velocity from 0.5 to 1.5 m s
-
1
, drying time decreased up to 42%. The
spe
cific moisture extraction rate values were found to vary between 0.078 and 0.18
K
g
Kw
-
1
h
-
1
. The minimum value of energy consumption was 3312 kJ at air temperature of
60ºC and air velocity of 1.5 m s
-
1
. Also, the total energy consumption of dryer with heat
pump was reduced by 19%, which reflects the higher energy efficiency.
Keywords
: Drying rate, Energy efficiency, Solar drying
