Car exhaust heat recovery is being investigated in recent years as a way to increase the efficiency of Internal Combustion engines . Also to reduce CO2 emissions by converting the thermal energy to electrical, employing either thermal fluid systems (mainly the Rankine Cycle) or Thermoelectric Generators. Research has shown that conversion of 10% of this waste heat into electricity may result to an increase of fuel efficiency of up to 20%. Particularly, in the case of heavy duty vehicles . There is evidence in the literature that assuming certain designs and manufacturing costs, a heat recovery system can increase the efficiency by almost 30%.

1. Presentation on environmental and
economic benefits of car exhaust
heat recovery
Presented By
Rajbala Purnima Priya

2. Contents
1. Introduction
2. Exhaust heat recovery (EHR)efficiency and cost
analysis
3. A Rankine Cycle EHR system
4. A TEG EHR system
5. Results and Conclusions

3. Introduction
Car exhaust heat recovery is being investigated in recent years
as a way to increase the efficiency of Internal Combustion
engines .
Also to reduce CO2 emissions by converting the thermal energy
to electrical, employing either thermal fluid systems (mainly the
Rankine Cycle) or Thermoelectric Generators.
Research has shown that conversion of 10% of this waste heat
into electricity may result to an increase of fuel efficiency of up to
20%. Particularly, in the case of heavy duty vehicles .
There is evidence in the literature that assuming certain designs
and manufacturing costs, a heat recovery system can increase
the efficiency by almost 30%.

4. Transport is responsible for around a quarter of EU greenhouse
gas emissions making it the second biggest greenhouse gas
emitting sector after energy.
Road transport alone contributes about one-fifth of the EU's total
emissions of carbon dioxide (CO2), the main greenhouse gas.

5. Both Light Duty Vehicles (LDVs) and Heavy Duty Vehicles (HDVs)
employ Internal Combustion (IC) engines, which produce an amount of
energy the majority of which is mainly dissipated in the form of heat
through the exhaust gases.
Fig Energy flow of an Internal Combustion engine

6. Exhaust heat recovery (EHR)efficiency and cost analysis
A Rankine Cycle EHR (RC-EHR) system comprises of four main components:
1. Evaporator/heat exchanger,
2. Expander
3. Condenser
4. And circulation pump..
Fig. A Rankine Cycle EHR system

7. Thermoelectric Generator(TEG) EHR (TEG-EHR) system which
comprises of three main components: 1. Thermoelectric generator 2.Heat
coupler to the exhaust pipe 3.And a cooling coupling to the engine
cooling tank.
The temperature difference between the hot and cold surfaces of TEG
induces a current that may be used for the charging of the HDV
battery.
Fig: A
TEG EHR
system

8. Assuming that most truck engines today run at around 1500 rpm at cruising
speed of 100 Km/h, the exhaust temperature has a mean value of 440 °C.
Under these conditions, it is estimated that approximately 3.9% of fuel
energy can be recovered by a RC-EHR system. This is equivalent to an
approximately 17.5% of fuel consumption reduction.
Similarly, a TEG-HER system for diesel engines, incorporating new
thermoelectric materials is expected to recover about 4% of fuel energy.
This is equivalent to approximately 20% of fuel saving.
Consequently, for both HER systems, (i.e. RC-EHR and TEG-HER), the
total cost is assumed to be the same, i.e. a total cost of 16,000 Euros.

9. Results and Conclusions
The recoverable energy by an Exhaust Heat Recovery (EHR) system
based on both Rankine Cycle and Thermoelectric Generator was
analyzed together with the cost of a 4KW HER for heavy duty
vehicles.
Finally, the cost and carbon emission pay back times of trucks fitted
with EHR system were calculated, assuming fixed fuel prices and high
annual mileage.
Service, annual authority inspection, insurance and tax are assumed
to be the same for the three aforementioned HDV categories and
have not been taken into consideration.

10. Reference
All the references, contents, results are taken in this
presentation from the paper whose link is given below.
Eleni Avaritsioti, “Environmental and economic benefits of
car exhaust heat recovery”, Science Direct Transportation
Research Procedia 14 ( 2016 ) 1003 – 1012, 6th Transport
Research Arena April 18-21, 2016.
link:-
https://www.sciencedirect.com/science/article/pii/S23521465
16300801

11. THANKYOU