This document discusses waste heat recovery techniques in car engines and the role of nanotechnology applications. It describes how up to 70% of energy in internal combustion engines is wasted as heat in exhaust and coolant systems. Various waste heat recovery technologies are examined, including thermoelectric generators, Rankine cycles, organic Rankine cycles, and turbocharging. Nanotechnology can improve heat transfer by using nanofluids with higher thermal conductivity in coolant systems. Recovering even a portion of wasted heat could improve fuel efficiency and reduce emissions.

1. Supervised by : Majeed Abbasalizadeh
Prepared by : Ahmed Jassim Khalaf
WASTE HEAT RECOVERY
TECHNIQUES IN CAR ENGINES AND
THE ROLE OF NANOTECHNOLOGY
APPLICATIONS

2. Abstract
 Waste heat recovery is the use of thermal energy that would otherwise be
transferred to the environment to accomplish a useful function. Examples for
internal combustion engines include the use of engine coolant for cabin heat,
turbocharging to increase power density, bottoming cycles to produce additional
work from exhaust gas, or integrated exhaust manifold to facilitate engine warm-
up. The main pathways for heat rejection in the internal combustion engine that
are potential possible for WHR include the hot exhaust gases discharged from the
tailpipe, the engine coolant radiator, as well as the EGR and charge air coolers.

3. Introduction
 By 2040, the world energy consumption is expected to increase by 40%. 1/3rd of
the world energy consumption belongs to the transportation sector and from that,
85% consumes by the road transportation sector, Although there is a huge tend
towards renewable energy sources, still the petroleum-based energy sources
dominate the road transportation sector, in SI (spark ignition) engines, nearly
70% of the total energy is wasted as heat and in CI (compression ignition)
engines, nearly 60% is wasted as heat. Energy efficiency improvement by in-
cylinder techniques of the engines have become to its saturation levels. So,
introducing a waste heat recovery system is promising to enhance the efficiency
of the IC engines which will also result in reducing the fuel consumption and GHG
(greenhouse gas) emission .

4. Aims of study
1-To use the energy wasted in vehicles in the form of heat generated by the engine. From
the literature study conducted there was 14% energy wasted in vehicles
through vehicle exhaust gases .
2-To obtain a new energy source that can be used for vehicle needs such as a source of
charging current (alternator) and vehicle
accessories.
To reduce vehicle fossil fuel consumption by eliminating the alternator function that has
been burdening the engine performance.
3-To become an alternative energy source for a hybrid type vehicle.
4-To increase vehicle energy efficiency.

5. Energy distribution on Internal Combustion
Engine

6. Examples of heat recovery systems in cars
 1-Use of engine coolant for cabin heat
 2-Turbocharging to increase power density
 3-Bottoming cycles to produce additional work from exhaust gas
 4- Integrated Exhaust Manifold to facilitate engine warm-up

7. Waste heat recovery technologies for internal
combustion engines
 thermoelectric generators.
 the Rankine cycle.
 the organic Rankine cycle.
 turbo- compounding.
 the Kalina cycle.
 the Stirling cycle

8. THERMOELECTRIC GENERATORS
 Thermoelectric generators (TEG), which convert waste heat directly into electricity, are a
promising WHR technology for internal combustion engines . Such generators can be
used both to convert heat power into electricity and to convert electrical power into
cooling or heating power. The working principle of TEG is based on the Seebeck effect,
which converts the temperature difference between the hot side and cold side directly into
electricity. General technical aspects and the most common applications of thermoelectric
generators are presented , The advantages of using TEG technology in waste heat
recovery are its silent operation and high reliability . In addition, TEGs have no moving or
mechanically complex components, unlike systems based on Rankine cycle technology .
Thus, thermoelectric generators can have very long technical lifetimes, and it has been
shown that thermoelectric devices can exceed 100 000 h of steady state operation . The
primary challenge facing TEG is their relatively low thermal efficiency at the present
technology level . However, advanced thermoelectric materials such quantum-well (QW)
materials have been shown to have the potential to reach notably higher efficiency values
than commercially available bismuth telluride (Bi2Te3) , thus improving the feasibility of
TEG systems. An interesting future development could be the combination of
thermoelectric and photovoltaic systems to increase the obtainable power output.

9. THERMOELECTRIC
GENERATORS

10. Rankine cycle
 based on a working principle similar to that used in large-scale steam power plants.
The working principle of the cycle is as fol- lows: high pressure liquid is evaporated, at
a constant pressure, in the evaporator by introducing heat power to the system. The
high pressure vapor is then expanded to a lower pressure, and power extracted from
the expansion. The expander can be either a turbine or a volumetric expander, such as
a piston expander, and it can produce either mechanical power or be coupled to a
generator producing electrical power The low pressure vapor is then condensed back
into liquid form by removing heat from the fluid in the condenser, after which the
pressure of the liquid is raised in a feed pump. Conventional RCs use steam as the
working medium. The organic Rankine cycle (ORC) process is the same as the steam RC
process, with the exception that an organic working medium is used in the cycle
instead of steam.

11. Example of a simple Rankine process

12. The organic Rankine cycle
 The organic Rankine cycle is similar to the Rankine steam cycle, but uses an
organic fluid such as refrigerants and hydrocarbons instead of water as the
working fluid. The ordinary Rankine cycle uses thermal power to convert water to
steam, which expands through a turbine in order to generate electricity. The
organic Rankine cycle operates in the same way, however instead of using water,
which has a relatively high boiling point (100°C), the organic Rankine cycle uses an
organic fluid that has a much lower boiling point than water.

13. The organic Rankine
cycle

14. Turb compounding
Electrical Turbo Compounding
 Turbo generator is a component that is designed to be able to withstand the
vehicle’s wasted gas heat and produce the electrical energy. Electrical Turbo
Compounding is almost the same as a mechanical system. The difference is the
motion energy changes into electrical energy caused by high speed electric
generators. It is called as electrical turbine when the position of the turbine
generator separated from the turbocharger. But in some conditions, most of
electric generators are put in the same place as the turbocharger. This condition is
called a turbo generator.

15. Mechanical Turbo Compounding
 This system use mechanical turbo movement driven by exhaust gases to produce
new energy on the vehicle. The exhaust gas flow moves the turbine rotor and
these rotations are used as an additional input to the crankshaft. This system is
generally applied to the heavy duty diesel engine where this engine has a large
piston displacement and a fast exhaust gas flow. The related research shows the
increasing of energy efficiency is about 3-5%. The schematic diagram of
Mechanical Turbo Compounding

16. Schematic diagram of Mechanical Turbo
Compounding.

17. Other Technologies
 Other technologies are being researched at present for the utilization of waste
heat of IC engines. Other technologies include utilization of heat exchangers,
recuperator, regenerator, passive air preheaters, and finned tube heat exchanger
for ICEs exhaust waste heat recovery. Waste heat energy can be utilized not only
for increasing the efficiency of the engine, but also for other applications, for
example, the waste heat of stationary ICEs can be utilized for food drying
technology.

18. The application of nanotechnology in heat
recovery from the car
 Nanotechnology can be applied to recover heat from the car using refrigerants in automotive
applications The radiator is an important heat exchanger for cooling the engine. Usually,
water and ethylene glycol are used in vehicles as cooling fluids. However, these fluids have
lower thermal conductivity. In the automotive industry, coolants with better quality are being
searched to develop more efficient engines. In recent years, nanofluids have become more
attractive to car manufacturers, with higher thermal conductivity to increase heat transfer.
The nanofluid that will be used in the engine must have different thermal and physical
properties such as high thermal conductivity, specific heat capacity, boiling point as well as
low viscosity and freezing point. It must also be environmentally friendly by being non-toxic
and chemically inert and must not be corrosive so that It causes corrosion in the cooling
system. It will be fitting to increase the heat transfer performance of the cooling system and
use coolant with high thermal conductivity.

19. conclusion
 Investigations have found that an connected way of improv- ing the overall
efficiency of the fuel use in a car is to recover some of the wasted heat
 One remarkable advantage of Rankine-based technologies is their ability to
produce either mechanical or electric power. Another major advantage is their
higher efficiency compared to TEGs at the current technology level. As a
conclusion, future development and the ability to meet increasingly stringent envi-
ronmental regulations will be the major success factors in competition between
the studied technologies.

20. Thanks for listening