HEAT ENGINES AND REFRIGERATION

PRESENTATION BY GROUP 1 CLASS D

IDEHEN OSAHON MOSES 20559AYOKUNLE OLUWOLE DAVID 20530AHMAD ABUBAKAR SHEHU 20464NWABUEZE GIFT CHIMUANYA 20614AKHIGBE PETER OSEREME 20507MBEE OLEMAKPADU NELSON 20821

ANYANWU OBINNA THOMPSON 20825

OUTLINEINTRODUCTIONTHEORETICAL ANALYSES OF CYCLESPRACTICAL APPLICATIONSFURTHER RESEARCHCONCLUSION

INTRODUCTION

•Any device that transforms heat partly into work

•The working substance could beAir and fuel mixture in ICE

Steam in Steam Engines

What is a Heat Engine?

First Law of Thermodynamics

-a principle of conservation of energy

INTRODUCTION

HEAT Q

W

Heat Applied

Work Done

• It is impossible to transform all of the heat energy transferred to a system into useful work.

INTRODUCTIONSecond Law of Thermodynamics

Forward and Reverse enginesForward Engines Reverse EnginesHeat moves from hot

source to cold sinkWork is done by the

systemExamples are ICE,SE

Heat moves from cold source to a hot sink

Work is done on the system

Examples are Refrigerators and A/C

INTRODUCTION

1 to 2 Isothermal heat Supply3 to 4 Isothermal heat rejection2 to 3 Adiabatic Expansions (Isentropic)4 to 1 Adiabatic Compressions (Isentropic)

The Carnot Efficiency (1)

THEORETICAL ANALYSIS

Carnot Cycle

Best EfficientHeat supplied at upper fixed temperatureRejected at lower fixed temperature

Otto Cycle (Ideal Air Standard Cycle - Petrol Engine)1 to 2 Isentropic Compressions2 to 3 Reversible constant Volume heating3 to 4 Isentropic Expansions4 to 1 Constant Volume HeatingCompression ratio (2)

Efficiency , (3)

(4)  (5)Otto Cycle efficiency is a function of compression ratio.

THEORETICAL ANALYSIS

Diesel Cycle Develop by Diesel in 1892 Compression Ignition  1 to 2 Isentropic Compressions2 to 3 Reversible Constant Pressure heating3 to 4 Isentropic Expansion4 t0 1 Constant Volume cooling. Making similar computations (6)

  (7)

The efficiency depends on the compression and cut off ratios.

THEORETICAL ANALYSIS

𝛽=𝑣3𝑣2

Refrigeration Cycle

W

Q2

Q 1

(7) 

(8)

 

1

23

4

THEORETICAL ANALYSIS

PRACTICAL APPLICATIONS1. Internal Combustion Engine (in cars and

airplanes)

2. Gas Turbine Engine

Gas turbines are similar to piston engines except that the four steps occur at different places. The four sections include:1. The inlet section2. The compressor section3. The combustion section (the combustor)4. The turbine (and exhaust) section.Applicable in airplanes and gas power plants

3. Refrigerator and Air conditioner

The major parts of the AC/refrigerator are:Evaporator - Receives the liquid refrigerant. Converts liquid to gasCompressor - A pump that pressurizes gaseous refrigerant Condenser - Facilitates heat transfer to the surrounding. Gas is condensed to cool liquidExpansion valve - regulates refrigerant flow into the evaporatorMajor differences are : supply of gases, circulation system and type of vaporization

FURTHER RESEARCHEfficiency of heat EnginesPollutionMagnetic heat EnginesElectric Cars

CONCLUSIONHeat Engines and Refrigeration play

important roles in our lives.

THANKS FOR LISTENING

QUESTIONS?