This document discusses heat transfer in bioprocesses. It describes how heat is transferred between fluids through solid walls in equipment like heat exchangers to facilitate temperature regulation. Several common heat exchanger designs are examined, including double-pipe, shell-and-tube, and plate-fin heat exchangers. Heat transfer occurs primarily through conduction, with various flow arrangements and factors like surface area affecting the rate of transfer. Heat generation from microbial growth can be calculated based on substrate utilization and enthalpy balances are required to understand heat evolution in bioprocesses.

1. APPLICATION OF HEAT
TRANSFER IN BIOPROCESS
A.SHEIK ABDULLA
M.SORNAMALYA
M.THASLEEMA PARVEEN
3RD YEAR B.TECH(BIOTECH)
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2. HEAT TRANSFER
 In Bioprocessing, heat exchange/transfer occurs between the
fluids.
 Equipment is provided to allow transfer of heat while
preventing the fluids to contact with each other.
 Heat is transferred through a solid metal wall.
 Sufficient area is provided so that heat is transferred.
 Heat transfer is facilitated by aeration and turbulent flow of the
fluids.
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3. EQUIPMENT USED FOR HEAT
EXCHANGE IN BIOREACTORS
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4. TYPES OF HEAT EXCHANGER
 Double-pipe heat exchanger
 Shell and tube heat exchanger
 Plate –fin heat exchanger
single-pass shell and tube heat exchanger
double tube-pass heat exchanger
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5. DOUBLE-PIPE HEAT EXCHANGER
 It consists of two metal pipes , one inside the other.
 One fluid flows through the inner tube while the other fluid
flows in the annular space between the pipe walls.
 Due to this the hot fluid becomes cold and cold fluid becomes
warmer.
 It can be operated with counter current or co-current flow of
fluids.
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DOUBLE PIPE HEAT EXCHANGER
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FLOW ARRANGEMENTS
counter current
Fluid flows in opposite direction
co-current flow
Fluids flow in same direction
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SHELL-&-TUBE HEAT EXCHANGER
SINGLE-PASS SHELL-AND-TUBE HEAT
EXCHANGER
 It is used for all type of fluids.
 It occupies large surface area.
 The heat transfer system is in two sections :a tube bundle and a
shell or cavity.
 Where one fluid flows into the shell and other flows into the
tube.
 The shell and tube fluids pass through the length of the
equipment only once.
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SINGLE-PASS SHELL-AND-TUBE
HEAT EXCHANGER
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DOUBLE TUBE-PASS HEAT
EXCHANGER
 The flow of tube and shell fluids are countercurrent for one
tube pass and cocurrent for other.
 Due to the action of baffles cross flow of shell fluid normal to
the tubes.
 Temperature cross occurs where the temperature of the hot
fluids equals to the temperature of the cold fluid .
 This can be avoided by increasing the number of shell pass.
 So, heat exchangers with multiple shell-pass can be used.
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DOUBLE TUBE-PASS HEAT
EXCHANGER
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TEMPERATURE CHANGES IN
EXCHANGER
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PLATE-FIN HEAT EXCHANGER
 It uses plates and finned chambers to transfer heat between
fluids.
 It is made of layers of corrugated sheets separated by flat metal
plates.
 It has relatively high heat transfer surface area to volume ratio.
 Separate hot and cold fluid streams flow through alternating
layers of the heat exchanger.
 They are enclosed at the edges by side bars.
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14. PLATE-FIN HEAT
EXCHANGER
FLOW ARRANGEMENTS
 This allows for the two
fluids to result in cross
flow, counter flow and
cross-counter flow
 It can work in perfect
countercurrent
arrangement.
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MECHANISM OF HEAT TRANSFER
Conduction:-
By Fourier’s law, the rate of heat conduction is
Ǭ = – kA (dT/dy)
Where,
Ǭ - rate of heat transfer
k - thermal conductivity
A - surface area perpendicular to direction of heat flow
(dT/dy) - temperature gradient
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Steady state Conduction:-
From conduction,
Ǭdy = – kAdT
by integration,
Ǭʃdy = – kAʃdT
Ǭy = – kAT
In case of boundary condition T=T1 at y=0
Ǭ = ( kA/y) (T1 –T)
Ǭ at steady state is same at all point y including y=B and T=T2
Ǭ = (kA/B) ΔT
(kA/B) can be written as (1/RW)
RW = B/kA
RW = thermal resistance to heat transfer
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EFFECT OF THICKNESS ON SURFACE
AREA FOR HEAT TRANSFER
 In cylindrical geometry, the hot fluid is flowing inside a pipe
while cold fluid flows outside.
 Because of inside diameter is smaller than outside diameter,
the surface area for heat transfer between the fluid and the wall
are different from two fluids.
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 40% to 50% of energy are stored s a carbon source and which
gets converted into ATP remaining are released as a heat.
 Heat is directly related to growth for actively growing cells.
 Heat generated can be calculated using the heat of combustion
of the substrate and of cellular material.
ΔΗs /YX/S = ΔΗc +(1/YH ) - 1
Where,
ΔΗs – heat of combustion of the substrate
YX/S - substrate yield coefficient
ΔΗc - heat of combustion of the cells
(1/YH )- metabolic heat evolved /g of cell mass produced
HEAT GENERATION BY
MICROBIAL GROWTH
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ENTHALPHY BALANCE FOR MICROBIAL
UTILIZATION OF SUBSTRATE
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From eqn 1,
YH = YX/S /(ΔΗs - YX/S ΔΗc )
 ΔΗs andΔΗc can be determined from the combustion of
substrate and cells
 The degree of oxidation of the substrate has a strong effect on
heat released.
 The total heat evolution in a batch fermentation is
QGR = VL µnet X(1/YH ) (QGR ≈ 0.12QO2 )
Where,
VL – liquid volume
X – cell concentration
 That metabolic heat released during the fermentation can be
removed by the heat exchanger.
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REFERENCES
 Bioprocess engineering principle: Pauline M. Doran
 Bioprocess engineering basic concepts: Michael L. Shuler and
Fikret Kargi
 https://en.wikipedia.org/wiki/Plate_fin_heat_exchanger
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