Repeat Probiem 7.4 with unnned inner tubes. Write your comments.
Nominal diameter of the inner tube = 3/4 in. (Schedule 40):
do 2 0.02667 1n
di : 0.02093 m
Annulus nominal diameter = 2 in. (Schedule 40):
D1- = 0.0525 In
The following constructional information is available for a gasket-plate heat exchanger:
All port diameters
Vertical port distance
Horizontal port distanc
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Heat Transfer/Heat Exchanger
What is heat transfer?
Mechanism of Convection
Mean fluid Velocity and Boundary and their effect
on the rate of heat transfer.
Fundamental equation of heat transfer
Logarithmic-mean temperature difference.
ME-750E Design of Heat Exchangers
ME 750E Design of Heat Exchangers 3 credits. This course covers analytical models for forced convection
through tubes and over surfaces, experimental correlations for the Nusselt number and press
An aircooled refrigerant condenser is to be designed. A flattened tnbe with corrngated fins
will be used. The surface selected for tbe matrix is similar to Figure 10.4. The cooling load
(beat duty) is 125 kW. The refrigerant 134A condenses i
De oDramea oy calcUlatmg Itl Itp and tltp at the same Reynolds number,'
(at equal velocities).
Performance evaluation allows us to make a simple surface performance'
comparison between the thermal resistances of both fluid streams. The
Flow and Thermal Fundamentals
Boundary Layer Features
Boundary Layers: Physical Features
Velocity Boundary Layer
A consequence of viscous effects
associated with relative motion
between a fluid and a surface.
A region of the flow characterized by
Double Pipe Heat Exchanger
Double Pipe Heat Exchanger
A double pipe heat exchanger is one of the simplest form
of Heat Exchangers.
The wall of the inner pipe is the heat transfer surface.
The major use of these HX is sensible cooling or heating
Solar Water Heating
Okotoks Solar Seasonal Storage and District Loop Simplified Schematic
Glycol / Water
District Heating Loop
Central Plant Outline
Located on MR
Detached Garages with
Solar Collector roofs
A heat exchanger is required to heat treated cooling water with a flow reate of 60 kg/s from
10 to 50 oC using the waste heat from water, cooling from 60 to 20 oC with the same mass
flow rate as the cold water. The maximum allowable pressure
KNOWN: Variation of hx with x for laminar flow over a flat plate.
FIND: Ratio of average coefficient, h x , to local coefficient, hx, at x.
ANALYSIS: The average value of hx between 0 and x is
h x dx = x -1/2dx
lIlJIE-Pipe Heat Exchangers
Selection, Rating, and Thermal Design, Third Edifio.
H eat Exchangers
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Plate heat exchangers
The heat transfer surface consists of a number of thin
corrugated plates pressed out of a high grade metal.
The pressed pattern on each plate surface induces
turbulence and minimises stagnant areas and fouling.
Unlike shell and tu
5,000 kgfhr of water will be heated from 20°C to 35°C by hot water at 140°C. A 15C hot
water temperature drop is allowed. A number of double-pipe heat exchangers with annuli
and pipes each cemented in series will be used. Hot water flows thro
Type of Heat
The e-NTU Expressions
8 (NTU, C)
mixed and Cmin
1 to 2 shelland-
CONVECTIVE HEAT TRANSFER
Course material Adapted from:
1. Warren. L, McCabe, Julian,C. Smith and Peter Harriott, Unit Operations of
Chemical Engineering, 7th Edn., McGraw Hill International Edition, NewYork
2. Holman. J.P., Heat Transfer , 9