Electrical Engineering

Rajesh Gupta

Air Conditioning

Prof. Elec. Engg.

Air- Conditioning

IntroductionWhat you will know at the end of session? 1. Organizational Set up & a bit of

history2. Basic concepts in Air-conditioning.3. Capacity and Settings of AC coaches 4. System of Generation 5. Generation in EOG coaches6. How AC works in AC coach7. Development of RMPU 8. LHB coaches & Double Decker AC

train9. Take tour of LHB coach

Introduction

Sr.DEE/Chg

CTA SSE Control

HQ

RBOrganization

DEE/AEE

IntroductionA view at Coaching depot

IntroductionA view at Coaching depot

IntroductionA view at Coaching depot

Sick line of depot

Introduction

HISTORY OF AC COACHES

Air-Conditioning

The first Indian air-conditioned train was Frontier Mail which was introduced in 1934. Earlier, the AC coaches of the train were kept cool by using ice blocks. These were replenished at several halts along the line. A battery operated blower constantly blew air into these receptacles, and the cold air entered the insulated cars through vents.British officers used to travel by Frontier Mail. It was a challenge to maintain the temperature of the AC coaches. 

History of AC coaches

Air-Conditioning

The Frontier Mail was one of the first trains in  India to get an air conditioned car. The AC car started running from 1934.

History of AC coaches

Air-Conditioning

The North-Western Railway introduced air-conditioned stock in the late 1930's (the earliest was probably the Frontier Mail in 1936 or 1937). In 1952-53 there were air-conditioned services between Bombay and Howrah, Delhi and Madras (Grand Trunk Exp.), Bombay and Delhi, Bombay-Amritsar (Frontier Mail), Bombay-Viramgam (Saurashtra Mail), and Bombay-Ahmedabad (Gujarat Mail).These all used AC units that were mounted beneath the coach body (underslung), interconnected by pipes.

More on history of AC coaches

Air-Conditioning

The first fully air-conditioned train was introduced in 1956 between Howrah and Delhi. Popularly known as the AC Express, it ran on the Grand Chord. Later there were two, one running on the Grand Chord and the other on the Main Line. Another train popularly known as the AC Express was the Dakshin Exp. between Madras and New Delhi in the 1960s.AC Chair Car stock was introduced around 1955. Until about 1979, air-conditioning was available only in these and in AC First Class cars. Around 1979 the first two-tier AC coaches were introduced. The first 3-tier AC coaches were introduced in 1993 (RCF)

More on history of AC coaches

Air-Conditioning

BASIC AIRCONDITIONINGConcept of Human

Comfort

Air-Conditioing

Difference between Air Conditioning & Refrigeration

Factors of ComfortTemperatureHumidityAir FlowNoise

Purity of Air

Air-Conditioning

Air-conditioning – comfort factors• Factors deciding comfort level

• temperature • humidity• draft (velocity of air)• purity of air• Noise

• Humidity – ratio of the moisture contained in a given quantity to the quantity of moisture required to saturate that quantity at a particular temp. It is termed as Relative Humidity (RH).

Air-Conditioning

Unit of Refrigeration• Unit of Refrigeration – in ton (TR)• It refers to the latent heat required to melt a ton of

ice at 32 degree F in 24 hours• 1 ton = 2000 lbs• Latent heat of Water to freeze -144 BTU/Lb 1 TR = 2000X144 =12000 BTU/Hr

24 = 3000 k Cal/Hr

Air-Conditioning

1TR of Refrigeration capacity?

1 TR Can Cater to Approx.

100 SQFT. (Area)

or 1200 CUFT. (Space)

Air-Conditioning

Relative HumidityAir has capacity to trap moisture. Its capacity to trap moisture varies with temperature.

Temperature 1 Cuf of air 70 deg.F 4 grains 80 deg.F 11 grains 90 deg.F 19 grains

1 kg of water = 15400 grains of moisture

Air-Conditioning

Outside ambient air (say 100 deg. F with 95% RH) is sent over the evaporator at 40 deg. F, moisture is condensed. When this air goes inside the AC compartment it rises to 70 deg. F and as there is now less moisture, the RH becomes 50 % inside.

Method to control RH

Air-Conditioning

Refrigerant• Freon 12 or Freon 22 (Chloro-

difluoromethane) gases • These are chemical Compounds. Freon

is the Trade name. In India the Trade name is Mafron. Manufactured by Navin Fluorine Industries

• To be re planned by non CFC gases by 2012 - to reduce Ozone layer depletion

• R-134 (Tetrafluroethane) a is being used now (Non CFL)

Air-Conditioning

CAPACITY AND SETTINGS OF AC COACHES

Air-Conditioning

Capacity of AC Coaches

As per heat load calculation, Load and Plant capacity of various Coaches

LOAD CAPACITY

• AC II tier 8 TR 2 Plants x 5.3 TR

• AC Ist 5.3 TR 1 Plant x 6.7 TR

• AC Chair Car/III tier 2 Plants x 6.7 TR

Air-Conditioning

Other settings in AC Coach• Fresh air requirement

– Smoking not permitted 0.35 meter cube/min/ passenger

– Smoking permitted 0.7 meter cube/min/

– passenger

• Air Velocity– up to 0.2m/sec inside the compartment– 4 m/sec at the diffuser

Air-Conditioning

Temperature settings in AC Coach

Low MediumHigh

• I AC Cooling 220 C 240 C260 C Heating 170 C 190 C210 C

• II AC Cooling - 240 C 260 CIII AC Heating - 190 C 210 C

Air-Conditioning

SYSTEM OF GENERATIONFOR AC COACHES

Air-Conditioning

Air- Conditioned Coaches

• Air-conditioned Coaches broadly classified as-• Self generating type

• Power for AC equipments is supplied by axle driven alternators at 110V DC

• End on generation type‑• Power from diesel generated sets (DG

sets) at both ends at 750 V AC 3 phase 50 Hz.

• AC equipments operate at 415 V 3 phase 50 Hz. AC

Air-Conditioning

SYSTEM OF GENERATION

IN EOG COACHES

Air-Conditioning

Supply System in End on generation ‑ ‑Coaches• Power supply for air-conditioning, lights and fans is

obtained by tapping from one of the two feeders of 750 V, 3 phase, 50 HZ emanating from the Power Car

• Each coach is provided with 50KVA transformer which steps down voltage to 415 V, 3 phase

• All AC equipments i.e. compressor, condenser, evaporator, heater etc. work on 415V, 3 phase

Air-Conditioning

Supply System in EOG Coachescontd…• For supply to lights and fans, each coach

is provided with a step down transformer of capacity 3 KVA - steps down the voltage from 415 V, 3 phase to 190 V, 3 phase.

•110 V a.c. supply is provided for lamps and fans by connecting them between line and neutral of the secondary side of transformer

Air-Conditioning

Supply System in EOG Coaches contd…A 24 V emergency battery of 90 Ah capacity has been provided on the under frame along with a battery charger. The battery supplies the emergency lights provided in the Coach in the event of a. c. power failure.

Air-Conditioning

Battery Charging at the Terminal Stations For pre cooling , AC Coaches are provided ‑

with

• One 200A capacity battery charger • The battery charger takes 440 V, 3 phase

supply through special battery charging sockets mounted diagonally one on each end wall.

• The battery charger consists of a transformer and a simple diode bridge rectifier.

Air-Conditioning

Refrigeration cycle

Refrigeration cycle – conventional coach

Heating cycle – conventional coach

Air-conditioning system working

Air-Conditioning

Equipments of AC SystemCompressor – compresses & delivers gas into condensers at a high pressure & high temperatureCondenser – it cools the hot gas and liquidates it under pressureExpansion Valve – It controls and regulates the rate of flow of liquid freon under high pressureEvaporator –the cooling unit in which liquid freon under low pressure evaporates & in-doing so takes away the latent heat thereby cooling the medium surrounding the cooling coil

Air-Conditioning

• In conventional type – AC equipments provided on under-frame

• Operates on 110 V DC supply through 18/25 KW alternators

• Thermostat senses the inside temperature of the coach

• Battery charger is provided on under-frame for charging the batteries

• Pre-cooling sockets are provided on either side of the coach for pre-cooling purpose

AC system in conventional type Coaches

Air-Conditioning

Under slung Type AC System

Air-Conditioning

BRUSH LESS ALTERNATOR

Air-Conditioning

Refrigerant gas leakage from pipes and jointsHeavy weight - coach tare weight increasesLarge space occupation by the equipmentsMaintenance problems - Huge skilled manpower required Consumes more power - Less energy efficientUnder-slung equipments get hit by ballast, CROAccumulated dust affects heat transfer

Drawbacks of Conventional AC system

Air-Conditioning

Development of RMPU• Reliable static Inverters (for

conversion of 110 volt dc into 3-phase ac)

• Use of 3- phase brushless compact motors possible.

• Development of Package Units for Rolling Stock applications

• Disadvantages of Opentype (underslung) eliminated.

• Weight advantage - one Ton against three Tons)

Air-Conditioning

RMPU of 5.2 introduced in the year 1992 with 25 KW alternator

• AC II tier & AC III tier - Two units of 7.0 TR

• First AC - one unit of 7 TR

• Mounted above the toilets on both ends supplying conditioned air in the tapered duct to serve the coach end to end

Roof-Mounted Packaged Unit (RMPU)

Air-ConditioningRoof-Mounted Packaged Unit (RMPU)Top view

Air-Conditioning

LOOK ONTO THE COMPRESSORS

Air-ConditioningComparison of RMPU with Conventional under-frame AC system

RMPU Conventional AC

Weight 900 Kgs (2 units)

2700 kgs

Installation time

4 hrs 4 days

Refrigerant R – 134a R – 12Refrigerant charge

2.85 Kgs 15 Kgs

Danger due to cattle run over / flood

Nil Heavy

Down time for repairs

4 hrs. Very long time

Air-Conditioning

Linke Hoffman Bosch (LHB) coaches

• State of the art coaches Rajdhani / Shatabdi Exp. Trains Modern passenger amenities

• Technology transfer M/s Alstom – LHB of Germany

• Manufactured at RCF, Kapurthala From the year 2003

Air-ConditioningLHB Coaches

Aesthetically superior Interiors

Very low noise

Fire retardant materials

Modular toilets with controlled discharge

Light weight

Air-Conditioning

GENERAL FEATURES OF LHB COACH

IV COUPLER

EXT. SUPPLY SOCKET

BATTERIES BATTERY FUSE BOX

AC PACKAGE UNIT FRESH AIR INTAKE

EXHAUSTFAN

Air-Conditioning

Basic Components of LHB Coach

Air-Conditioning

Basic Components of LHB Coach

Air-Conditioning

Basic Components of LHB Coach

Air-Conditioning

Basic Components of LHB Coach