1. Heat Transfer in a Rotary Drum via Conduc6on, Convec6on, and Radia6on
Brandon Boepple, Chemical Engineering
Mentor: Dr. Heather Emady, Assistant Professor
School for Engineering of MaDer, Transport, & Energy
How is heat transfer in a rotary drum affected by opera6ng parameters such as granular fill level and drum rota6on rate?
Heat transfer occurs via 3 modes: conduc6on, convec6on, and radia6on. A
general equa6on for total heat transfer is:
In this applica6on, heat is transferred through wall-par6cle, par6cle-
par6cle, wall-air, and par6cle-air contacts. First, we will complete
experiments for conduc6on hea6ng through wall-par6cle, wall-air, and
par6cle-par6cle contacts. The drum will be heated externally and is
assumed to be sealed so that convec6on effects can be neglected. By
opera6ng below roughly 600 K, effects from radia6on are also neglected.
From this first round of experiments, we can calculate Qcond.
Next, we will perform experiments to study convec6on hea6ng by
inser6ng hot air into the drum via a hole in the viewing window. From this
round of experiments, we can calculate Qconv from Qtot - Qcond.
Lastly, we will consider hea6ng via radia6on by opera6ng at temperatures
above 600 K. From this round of experiments, we can calculate Qrad from
Qtot – Qcond – Qconv.
These values of heat transfer coefficients will be calculated from heat
balance equa6ons; the following example equa6on is a heat balance
between the drum wall and granular bed. Values of αs can be calculated
from the slope of the best-fit line from the graph of ln(T) vs. 6me.
Qtot = Qcond + Qconv + Qrad
Methodology
Future Work Experimental Setup
Acknowledgements
Chaudhuri et al., Experimentally validated computa6ons of
heat transfer in granular materials in rotary calciners,
Powder Technology 198 (2010).
Manogna Adepu, Graduate Research Associate
• The drum is 3 in. long with an inner diameter of 6 in.
• Stainless steel (common in industry).
• The blue circle is the air inlet hole.
• The green circles are the exhaust holes.
• The red surrounds the 10 thermocouple inlet holes.
• The front window is a sapphire material that can
withstand 600+ K for infrared viewing purposes.
Rollers for rota6ng the
drum.
2 heat guns will be used
to heat the drum. They
can reach temperatures
up to 900 K.
Thermocouple (boDom),
wireless transmiDer
(led), and receiver (right)
will be used to collect
temperature data.
3mm silica beads, a
common catalyst in
many industries.
• Conduct experiments to quan6fy all 3 heat transfer
mechanisms.
• Inves6gate the effects of fill level and rota6on rate.
• A DOE chart for the conduc6on experiments is shown
below, including a total of 48 experiments.
The mass required for each fill
level was calculated using the
following equa6on:
Mass=(Fill level)*Φ*ρ*π*R2*L
where Φ is solids frac6on, ρ is
density of par6cles, R is radius
of drum, and L is length of
drum.
Fill Level Mass (g)
10% 213.6
15% 320.4
20% 427.2
25% 534.0
S.No Fill level
RotaCon
speed Trial
(%) (rpm) 1 2 3
1 10 1 1101 2101 3101
2 10 5 1105 2105 3105
3 10 10 11010 21010 31010
4 10 20 11020 21020 31020
5 15 1 1151 2151 3151
6 15 5 1155 2155 3155
7 15 10 11510 21510 31510
8 15 20 11520 21520 31520
9 20 1 1201 2201 3201
10 20 5 1205 2205 3205
11 20 10 12010 22010 32010
12 20 20 12020 22020 32020
13 25 1 1251 2251 3251
14 25 5 1255 2255 3255
15 25 10 12510 22510 32510
16 25 20 12520 22520 32520
Future experiments may also include the use of an infrared
camera to gather temperature data while the process is
running. This would enhance the accuracy of the results.
IntroducCon
Rotary drums have many industrial applica6ons with granules, but
granules don’t behave like conven6onal solids, liquids, or gases which
makes these processes difficult to model and op6mize. The purpose of this
research is to quan6fy all three modes of heat transfer in the granular bed
and study which modes dominate under varying opera6ng condi6ons.