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EXPERIMENAL INVESTIGATION ON HEAT RECOVERY FROM DIESEL ENGINE EXHAUST

SEMINAR BY

AMAL SAJIKUMAR

M Tech R# 123

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INTRODUCTION

Waste heat is generated by fuel combustion or

chemical reaction in an IC engine.

Exhaust gas from an IC engine carries away about

30% of the heat of combustion.

Nearly two-third of input energy of a diesel engine is

wasted through exhaust gas and cooling water.

A process is launched for conserving this energy is

waste heat recovery techniques.

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Contd…

A shell and finned tube heat exchanger integrated with

an IC engine setup to extract heat from the exhaust gas.

A Thermal Energy Storage (TES) tank used to store the

excess energy available.

A combined sensible and latent heat storage system is

designed.

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Thermal Energy Storage(TES) systems

The energy recovered from exhaust gases can be

stored here.

In sensible heat storage (SHS), thermal energy is

stored by raising the temperature of a solid or liquid.

The amount of heat stored depends on the specific

heat of the medium.

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CONTD…

Latent heat storage (LHS) is based on the heat

absorption or release

when a storage material undergoes a phase change

from solid to liquid or liquid to gas or vice versa.

Combination of sensible and latent heat storage is

always a better alternative.

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Phase Change Materials (PCM)

PCM are Latent Heat Storage materials.

PCM absorbs and release heat at a nearly constant

temperature.

They store 5-14 times more heat per unit volume than

sensible storage materials.

PCM are economical and easily available. Parraffin is

commonly used PCM material.

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Experimental investigation

Major criterion in the design of waste heat recovery

system is the proper selection of heat exchanger.

Objective is to extract heat from the exhaust gas and

to store it in the storage tank.

A separate heat exchanger with HTF is circulated to

extract heat.

Heat is then deliver it to the storage medium present in

the TES tank.

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Schematic diagram for experimental setup

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Selection of heat exchanger and storage tank configuration

Finned shell and tube heat exchanger is selected to extract heat.

Circular tubes are used in the heat exchangers.

Heat transfer fluid (HTF) used to extract heat from exhaust gas is castor oil.

Heat transfer coefficient for gases will be very low.

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CONTD…

Gas side needs to have larger area for better heat transfer.

It cannot be achieved by embedding the heat exchanger coil inside the storage tank.

So a separate HE with finned tubes are provided.

Exhaust gas is passed through shell side.

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Heat recovery system is a heat exchanger.

Shell side fluid –Exhaust gas.

Tube side fluid-Castor oil(HTF).

Four number of longitudinal copper fins are attached to

each tube at regular intervals.

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cross sectional view of the heat exchanger.

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The TES tank is a stainless steel cylindrical vessel.

It contain castor oil as the sensible storage medium

and paraffin as the latent storage medium.

The storage tank contain 15 kg paraffin filled in 48

capsules and 55kg of castor oil as the HTF.

The cylindrical capsules are kept in a mild steel stand,

having four wire meshed decks as shown below:

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Layout of thermal storage tank

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PCM container (paraffin)

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The temperature at various locations are recorded using

Cr/Al thermocouples.

Twelve thermocouples are placed in four different

horizontal planes.

Three thermocouples are placed uniformly in each plane

and also at inlet and outlet of HRHE and TES tank.

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Thermocouple location in storage tank

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PERFORMANCE OF HEAT RECOVERY HEAT EXCHANGER

Temperature variation at 25% load

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Temperature variation at 50% load

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Temp: variation at 100% load

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Heat extraction rate from exhaust

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Temperature distribution in TES system

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Charging rate and charging efficiency

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Percentage energy saved

25% 50% 75% 100%0

2

4

6

8

10

12

14

16

LOAD (%)

EN

ERGY

SAV

ED (%

)

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CONCLUTION

The effectiveness of the HRHE approaches

nearly 99% at the end of charging process at

all load conditions.

Nearly 10–15% of total heat (that would

otherwise be gone as waste) is recovered with

this system.

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CONTD…

The maximum heat extracted using the heat

exchanger at full load condition is around 3.6

kW.

Both the charging rate and charging efficiency

are very high at higher load and they decrease

with respect to load.

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Reference

Zalba Belen, Jose Marin M, Cabeza Luisa F, Mehling Harald. Review on thermal energy storage with phase change: materials, heat transfer analysis and applications. Appl Therm Eng 2008;23:251–83.

Sharma Atul, Tyagi VV, Chen CR, Buddhi D. Review on thermal energy storage with phase change material and applications. Renew Sustain Energy Rev 2009;13:318–45.

Talbi M, Agnew B. Energy recovery from diesel engine exhaust gases for performance enhancement and air conditioning. Appl Therm Eng 2009;22:693–702.

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THANK YOU…