kuliah 1 introduction- ice

KM30803 APPLIED THERMODYNAMICS

DEFINITION OF ENGINE


INTRODUCTION TO ENGINE (ICE)

Definition of Engine

Definition of Heat Engine

External and Internal Combustion Engine

Basic Engine Component

Nomenclature

The Working Principle of Engine, four stroke/ two stroke

FUEL AIR CYCLE AND THEIR ANALYSIS

Fuel Air Cycles and their Significance

Composition of Cylinder Gases

Variable Specific Heat

MEASUREMENT AND TESTING IN ICE

Introduction

Indicated power

Brake power

Fuel consumption

Air consumption

Speed


An engine is a device that transforms one form ofenergy into another form.

Efficiency of conversion plays an important role intransformation of energy

Normally, most of the engines convert thermalenergy into mechanical energy/work and they arecalled heat engines (transforms chemical energy offuel into thermal and utilizes thermal energy foruseful work).


CHEMICAL ENERGY IS CONVERTED INTOTHERMAL ENERGY BY COMBUSTION

THERMAL ENERGY IS CONVERTED INTOMECHANICAL ENERGY


PURPOSE

THE PRODUCTION OF MECHANICAL

POWER FROM THE CHEMICAL ENERGY

CONTAINED IN THE FUEL


EXTERNAL AND INTERNAL ENGINE

Combustion is the act of burning. Internal means inside or enclosed. Thus, in internal combustion engines, the burning of fuel takes place inside the engine; that is, burning takes place within the same cylinder that produces energy to turn the crankshaft.

In external combustion engines, such as steam engines, the burning of fuel takes place outside the engine. Figure in next slides shows, in the simplified form, an external and an internal combustion engine.

The external combustion engine contains a boiler that holds water. Heat applied to the boiler causes the water to boil, which, in turn, produces steam. The steam passes into the engine cylinder under pressure and forces the piston to move downward.


EXTERNAL

COMBUSTION ENGINE

STEAM LOCOMOTIVE


INTERNALCOMBUSTION ENGINE


ENGINE CLASSIFICATION

1.Based on ignition type

a. SI

b. CI

2.Engine cycle

a. Four stroke cycle

b. Two stroke cycle

Three and six stoke cycles were also tried earlier


4 Stroke SI engine


Four-Stroke Diesel Engine

A-Intake stroke Intake valve open, exhaust

valve shut Piston travels from TDC to BDC Air drawn in

B-Compression stroke Intake and exhaust valves shut Piston travels from BDC to TDC Temperature and pressure of

air increase

C-Power stroke Intake and exhaust valves shut Fuel injected into cylinder and

ignites Piston forced from TDC to BDC

D-Exhaust stroke Intake valve shut, exhaust

valve open Piston moves from BDC to TDC Combustion gases expelled


4 Stroke CI engine - Diesel


Two Stroke Spark Ignition Engines

Stroke 1: Fuel-air mixture is introduced into the cylinder and is then

compressed, combustion initiated at the end of the stroke

Stroke 2: Combustion products expand doing work and then

exhausted

Power is delivered to the crankshaft on every revolution

Application

Small Engines Absence of valve mechanism makes cheaper, compact and lighter engines

Large Engines That operates at a low RPM. Requires a power stroke from every revolution for smooth operation.


2 Stroke SI engine


In two stroke engines the

crankcase is a pressurization

chamber to force fuel/oil/air

into the cylinder. Here, we mix

oil and gas to lubricate internal

parts.

In four stroke engines the

crankcase is separate from the

compression chamber. This

allows the use of heavy oil for

lubrication.

The engines do not last as long

due to poor lubrication.

Increased heating due to more

number of strokes limits the

maximum speed.

The engines do not use fuel

efficiently.

These engines produce a lot of

pollution.

Greater cooling & lubrication

requirements

Power output is only more than

30 % and not doubled

kuliah 1 introduction- ice

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