Bread Toaster. ⢠Ambulance. ⢠Safari rides. Hot. Box. Cold Water. Inlet. Hot Water Outlet. ⢠To recover heat from exhaust pipe and used it to maintain items ...
NON INTRUSIVE EXHAUST GAS HEAT RECOVERY SYSTEM FOR AN AUTOMOBILE: A PRELIMINARY INVESTIGATION David Neihguk, Aravindh TR, Samir Rawte Mahindra & Mahindra Ltd.
Finding out what customers want without directly asking them
• “Some customers do carry food items on board while driving, especially in long trips.” - SUV customer survey at Mahindra Dealership in Chennai
• Most Taxi drivers driving at night frequently stops at highway tea stalls to have a cup of coffee to keep themselves awake for the trip.
The answer to this is “Hot Box” SAE INTERNATIONAL
Paper # 2013-01-2808
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Objectives
• To recover heat from exhaust pipe and used it to maintain items temperature at 63°C (Food Safety Temperature Control, UK).
Outlet Port Double Pipe Heat Exchanger Intermediate Exhaust Pipe
SAE INTERNATIONAL
Paper # 2013-01-2808
Flow Direction
4
Hot Box Circuit
Hot Water Outlet
Water Inlet
Hot water Inlet Return line
Hot Box
Hot Water Outlet
Cold Water Inlet
Swi tch
Pump
Heat Exchanger Unit
Hot Box
Heat exchanger
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Paper # 2013-01-2808
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Optimization of heat exchanger length
Table : Optimization of Heat Exchanger length
S.No
Length (mm)
Volume (L)
Temperature (o C)
1
500
4.4
208
2
450
4
198
3
400
3.5
186
4
350
3.1
173
5
300
2.6
158
6
250
2.2
140
7
200
1.7
121
8
150
1.3
98
9
100
0.8
73
Figure : Optimization of length of Primary Heat Exchanger SAE INTERNATIONAL
Paper # 2013-01-2808
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Simulation results
Fig: Contours temperature variation in Water regime & Exhaust Gas
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Paper # (if applicable)
Fig: Exhaust Pipe temperature
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Simulation results
Graph: Comparison of Outlet water temperature(K) SAE INTERNATIONAL
Paper # (if applicable)
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Testing Results
Table : Results of Static testing T1 T2 T3 T4 T5
Initial 34 34 31 31 31
After 15 minutes 95 90 37 34 39
Table 3. Results of Dynamic testing at 10 kmph
T1 T2 T3 T4 T5
Initial 36 38 36 33 36
Final 121 111 45 35 50
Table 4. Results of Dynamic testing at Highway Driving
where T T1 T2 T3 T4 T5
Temperature in degree Celsius Exhaust gas temperature before heat exchanger Exhaust gas temperature after heat exchanger Hot Box temperature Cold water temperature Hot water temperature
SAE INTERNATIONAL
Paper # 2013-01-2808
T1 T2 T3 T4 T5
Initial 36 38 36 31 36
Final 348 336 82 33 94
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LMTD
The Log mean temperature difference for a parallel flow double pipe heat exchanger is given by equation:
The log mean temperature difference for the three cases are as given below
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Testing Condition
LMTD
Static At 10 kmph
55.85 72.75
Highway driving
276.89
Temperature measurement at highway driving condition
400
Temperature in degC
350 300 250 T1
200
T2 T5
150
1st Stop
100
T3
2nd Stop 65 deg C Hot Box Temperature
50 0 0
1000
2000
3000
4000 5000 Time in Seconds 45 minutes for Data logger preparation 48 minutes for Hot Box to reach and Security Clearances 65 deg C despite two stops in between
Results T1 T2 Initial 117.27 112.12 Maximum 347.87 335.82
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T3 35.66 82.27
T4 32.78 32.78
T5 LMTD 32.78 93.87 277.79
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6000
7000
8000
Abbreviations T1= Exhaust Gas Temperature before Heat Exchanger T2= Exhaust Gas Temperature after Heat Exchanger T3= Hot Box Temperature T4= Cold Water Temperature T5= Hot Water Temperature 12
Proof of Concept demonstrated in SUV
• Hot Box Temperature (T3) of 82 deg C and Hot Water Temperature (T5) of 94 deg C achieved within less than 30 minutes of driving in Highway. • T1 and T2 are Exhaust Gas Temperature at Inlet and Outlet respectively
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Paper # 2013-01-2808
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Conclusions
• Adequate amount of heat energy can be recovered from the exhaust gas. • Further work needs to be done including the control strategies to regulate the hot box temperature. • Design of components to make the water fit for drinking is a challenge.
