Classification of Heat Exchangers P M V Subbarao Professor Mechanical Engineering Department I I T...
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Transcript of Classification of Heat Exchangers P M V Subbarao Professor Mechanical Engineering Department I I T...
Classification of Heat Exchangers
P M V SubbaraoProfessor
Mechanical Engineering Department
I I T Delhi
Creation of Variety in Anatomy of Heat Exchanger!!!
Time /Space Sharing
Real Need : Cool or heat a Fluid
Auxiliaries : Solid Surface & Another fluid (plentiful)
Essential : Some source of Energy (Motive Power)
More Green Methods…..
Traditional Egyptian architecture in Ancient Egypt as demonstrated on the Pharonic house of Neb- Ammun, Egypt,
19th Dynasty, c.1300 BC.
Persian: بادگیر bâdgir: bâd "wind" + gir "catcher“
Arabic: ملقف malqaf
Eastern Arabia:بارجيل barjeel
Windcatcher (Bagdir)
Degree of Greenness
Geometrical Ideas for Classification
Regenerators
Relative Direction of Flows
Scalar HX to Vector Hx
Economy of Metal Usage
dido Di
Geometrical Modifications for Better Economy
Expenditure in A Heat Exchanger
• The capital investment on Heat exchanger material is proportional to double the Heat transfer Area.
• Investment on both cold side and hot side of a heat exchanger for a given surface area of heat exchanger.
• Another expenditure is running cost or operational cost.• Main operation cost is pumping power cost.• This again increases the size of the pump and capital cost.• This arises a question of inner and outer flow pressure
drop calculations and a suitable innovation for the same.• Engineering world is like an incandescent lamp.
Two inner tubes and one outer tube
inhh Tm , & outhh Tm , &
incc Tm , &
outhc Tm , &
1cT
2cThT
Differential Element Analysis
dz
1cdT
hdT1Q2Q
2cdT
1,1 ccpcold dTcmQ
2,2 ccpcold dTcmQ
11,1 chccpcold TTUadzdTcmQ
22,2 chccpcold TTUadzdTcmQ
11,
chccpcold TT
dz
dT
Ua
cm
22,
chccpcold TT
dz
dT
Ua
cm
Heat lost by hot fluid:
2121, chchhhphot TTTTUadzQQdTcm
21, 2 cchhhphot TTTUadzdTcm
21, 2 cch
hhphot TTTdz
dT
Ua
cm
11,
chccpcold TT
dz
dT
Ua
cm
22,
chccpcold TT
dz
dT
Ua
cm