Energy Consumption Analysis for a Single Screw Extruder - Intelligent Computing for Sustainable Energy and Environment - page 538

lasts around 90 minutes in which the first 30 minutes was allocated for the machine to
reach its equilibrium point, and the data was recorded for the rest 60 minutes. The re-
sultant total thermal energy consumption (from zone 1 to adapter), total extruder active
energy consumption, motor drive active energy consumption, extruder power factor,
motor drive power factor, ratio of zone 1 energy consumption to the total thermal en-
ergy usage, overall specific energy consumption, thermal specific energy consumption,
and motor specific energy consumption are provided in table 2 for each trail.

Ta b l e 2 . Effects of barrel temperature settings on the energy consumption (data was recorded for
50 minutes, the sampling rate was 10Hz)

DOE A DOE B DOE C

Barrel temperature setting low medium high

Total thermal energy (kwh) 0.808 0.910 1.000

Extruder active energy (kwh) 1.259 1.315 1.381

Motor drive active energy (kwh) 0.485 0.451 0.431

Extruder power factor 0.569 0.592 0.612

Motor drive power factor 0.419 0.412 0.406

Zone 1 vs total thermal 0.610 0.607 0.657

Total SEC (kwh/kg) 0.692 0.720 0.757

Thermal SEC (kwh/kg) 0.444 0.498 0.548

Motor SEC (kwh/kg) 0.266 0.247 0.236

The thermal energy was calculated from the temperature controllers, and the total
value is a little higher than measuring from a power meter. This is caused by the lower
sampling rate (1Hz) of the power meter, which is not capable of capturing the frequent
changes of barrel heating and cooling. Therefore, the sum of thermal energy and motor
active energy is slightly higher than the extruder active energy consumption. From table
2, higher barrel temperature settings lead to higher thermal energy consumption but
lower motor active energy consumption. However, the total specific energy is increased
at higher barrel heating temperature. This suggests that reasonable lower barrel heating
is preferred without determinately affecting the melt quality.

4.2 Feed Area Cooling

The feed area cooling temperature setting not only affects the extruder energy consump-
tion, but also determines the chiller energy usage. It has been studied that increasing the
flow temperature by 4 ◦ C will decrease chiller operating costs by 10% [9]. The selection
of chiller temperature setting should also consider the atmosphere temperature in order
to save the cooling energy. For this KTS-100 single screw extruder, increasing water
temperatures reduces energy usage in both thermal and motor drive (table 3). However,
the power factor slightly decreased. As the effects are small compared to barrel tem-
perature settings, it might be reasonable to put more attention on chiller operating cost
instead of the extrusion while adjusting the water temperature settings.