COMPRESSED NATURAL GAS

CNG

When the natural gas is compressed, it is called Compressed Natural Gas (CNG). The primary component present in CNG is methane. It is mainly derived from natural gas. The natural gas can either be stored in a tank of a vehicle as compressed natural gas (CNG) at 3,000 or 3,600 psi or as liquified natural gas (LNG) at typically 20-150 psi.

CNG

Constituents Percentage (%)Methane 88.5

Ethane 5.5

Propane 3.7

Butane 1.8

Pentane 0.5

CNG

• CNG is made by compressing natural gas (which is mainly composed of methane [CH4]), to less than 1% of the volume it occupies at standard atmospheric pressure

• It is stored and distributed in hard containers at a pressure of 200–248 bar (2900–3600 psi), usually in cylindrical or spherical shapes

CNG- ADVANTAGES

• CNG is the cheapest, cleanest and least environmentally impacting alternative fuel.

• Vehicles powered by CNG produce less carbon monoxide and hydrocarbon (HC) emission.

• CNG is cheaper and cleaner• The octane rating of CNG is high, hence the thermal

efficiency is more.• It mixes very easily with air than the other gaseous fuels.• Noise level is much less than diesel

CNG- MODIFICATIONS1. CYLINDER: USED TO STORE CNG – SAFETY VALVE

2. HIGH PRESSURE PIPE LINE: CONNECTS THE REFUELING VALVE WITH CYLINDER & PRESSURE REGULATOR

3. REFUELING VALVE – USED TO REFUEL

4. PRESSURE REGULATOR:

5. GAS-AIR MIXER:

6. PETROL – SOLENOID VALVE:

7. SELECTOR SWITCH:

CNG VEHICLE

PERFORMANCE AND EMISSION CHARACTERISTICS

BRAKE POWER: 10% LOWER ( POOR VOLUMETRIC EFFICIENCY) BRAKE THERMAL EFFICIENCY: HIGHER BSFC AND BSEC: LOWER CO: LOWER HC: LOWER NOx: HIGHER

LIQUEFIED PETROLEUM GAS (LPG)

LPG

constituents

propane

Iso butane

N-butane

LPG• It occurs naturally in oil and gas fields

• It is obtained as a by-product during fractional distillation of crude petroleum oil or by cracking of heavy oil.

• It consists of propane and butane.

• It can be readily liquefied under pressure, so it can be economically stored and transported in cylinders.

LPG - Uses

1. It is used as a domestic and industrial fuel

2. It is also used as a motor fuel.

LPG- ADVANTAGES1. LPG consists of hydrocarbons, so it burns cleanly without leaving any residue.

2. The LPG (hydrocarbons) has higher calorific value than the other gaseous fuels. The calorific value is 7 times higher than coal gas and 3 times higher than natural gas.

3. LPG is characterized by high thermal efficiency and heating rate.

LPG- ADVANTAGES• LPG is cleaner• The octane rating of LPG is high, hence the

thermal efficiency is more.• It mixes very easily with air than the other

gaseous fuels.• Noise level is much less than diesel

LPG- ADVANTAGES• LPG is cleaner• The octane rating of LPG is high, hence the

thermal efficiency is more.• It mixes very easily with air than the other

gaseous fuels.• Noise level is much less than diesel

LPG- MODIFICATIONS1. CYLINDER: USED TO STORE CNG – SAFETY VALVE

2. HIGH PRESSURE PIPE LINE: CONNECTS THE REFUELING VALVE WITH CYLINDER & PRESSURE REGULATOR

3. REFUELING VALVE – USED TO REFUEL

4. PRESSURE REGULATOR:

5. GAS-AIR MIXER:

6. PETROL – SOLENOID VALVE:

7. SELECTOR SWITCH:

PERFORMANCE AND EMISSION CHARACTERISTICS

BRAKE POWER: 10% LOWER ( POOR VOLUMETRIC EFFICIENCY) BRAKE THERMAL EFFICIENCY: HIGHER BSFC AND BSEC: LOWER CO: LOWER HC: LOWER NOx: HIGHER