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TEMPERATURE INCREASES and PRESSURE DECREASES.

Temperature increases and pressure decreases.

n-heptane and ISO-octane.

n-heptane and ISO-octane.

In I.C. ENGINE MAXIMUM temperature ATTAINED is HIGHER than in gas TURBINE.

In I.C. engine maximum temperature attained is higher than in gas turbine.

Iso-octane permits highest COMPRESSION WITHOUT CAUSING KNOCKING.

Iso-octane permits highest compression without causing knocking.

It DECREASES thermal efficiency but INCREASES NET OUTPUT.

It decreases thermal efficiency but increases net output.

Because it has LOW FRONTAL AREA.

Because it has low frontal area.

LIQUID HYDROGEN has HIGHER BURNING VELOCITY.

Liquid hydrogen has higher burning velocity.

Because a large PORTION of turbine work is eaten AWAY by compressor and its inefficiency will affect NET POWER output and cost of generation.

Because a large portion of turbine work is eaten away by compressor and its inefficiency will affect net power output and cost of generation.

To DECREASE both MASS FLOW rate and WETNESS of STEAM.

To decrease both mass flow rate and wetness of steam.

RATIO of their THICKNESS = (PRANDTL NUMBER)-1/3.

Ratio of their thickness = (Prandtl number)-1/3.

CYCLONE FURNACE.

Cyclone furnace.

HEAT PUMP.

Heat pump.

Supercritical boilers do not head HEAVY drum for separation of steam from MIXTURE of WATER and steam.

Supercritical boilers do not head heavy drum for separation of steam from mixture of water and steam.

Superheater TUBES are subjected to the most severe combination of STRESS, temperature and corrosive environment. In addition to high-temperature strength, resistance to corrosion is also important. For example, low-alloy ferritic steel such as -1/% Cr, 1% Mo would not be USED at metal temperatures above 580°C because of inadequate resistance to corrosion and oxidation over a full service life of 100,000/150,000 hr.

FAILURES in superheater tubes may arise from :

1. Prior fabrication history
2. Faulty heat treatment
3. Consequences of welding
4. Overheating of the tube metal
5. Gas-side corrosion
6. Stress corrosion (AUSTENITIC steels).

Superheater tubes are subjected to the most severe combination of stress, temperature and corrosive environment. In addition to high-temperature strength, resistance to corrosion is also important. For example, low-alloy ferritic steel such as -1/% Cr, 1% Mo would not be used at metal temperatures above 580°C because of inadequate resistance to corrosion and oxidation over a full service life of 100,000/150,000 hr.

Failures in superheater tubes may arise from :

Boiler tubes, usually are made from carbon steel and are subject to

1. high rates of heat transfer,
2. bending stresses due to uneven heating, especially at expanded or welded joints into headers or drums,
3. external erosion from burners and flue gas,
4. possible corrosion on the boiler side, and
5. occasional manufacturing defects.

Failure may OCCUR due to following reasons :

1. High thermal ratings may lead to rapid failure if the internal fluid flow is reduced for any reason. The resultant overheating leads to a failure by creep, characterised by the bulging of the tube with the eventual development of a longitudinal split.
2. Fatigue cracking due to bending stresses occur. These are associated with change of SECTION and/or weld undercut, where tubes are expanded or welded into headers.
3. Failure may arise due to OVERSTRESSING of a reduced section of metal.
4. Sudden failure of the boiler tube due to corrosion arises from embrittlement of the carbon steel due to interaction between atomic hydrogen from the corrosion process and the iron carbide present in the steel.
5. Defects in tube manufacture, although far from being a regular occurrence, can be a cause of serious trouble. Lamination in boiler tubes or score marks arising from the cold drawing of tubes, GIVE rise to premature failure and may promote corrosion at these regions.

Boiler tubes, usually are made from carbon steel and are subject to

Failure may occur due to following reasons :

Thermostat ENSURES optimum cooling because excessive cooling decreases the overall efficiency. It ALLOWS cooling water to go to radiator BEYOND a predetermined TEMPERATURE.

Thermostat ensures optimum cooling because excessive cooling decreases the overall efficiency. It allows cooling water to go to radiator beyond a predetermined temperature.

Pistons are usually HOLLOWED at TOP to

1. PROVIDE greater space for combustion,
2. increase surface for flue gases to act UPON, and
3. better distribution of stresses.

Pistons are usually hollowed at top to

When liquid refrigerant as OBTAINED from condenser is throttled, there are some vapours. These vapours if carried through the evaporator will not CONTRIBUTE to refrigerating effect. Using a flash chamber at some INTERMEDIATE pressure, the flash vapour at this pressure can be BLED off and fed back to the compression process. The throttling process is then carried out in stages. SIMILARLY compression process is also done in two separate compressor stages.

When liquid refrigerant as obtained from condenser is throttled, there are some vapours. These vapours if carried through the evaporator will not contribute to refrigerating effect. Using a flash chamber at some intermediate pressure, the flash vapour at this pressure can be bled off and fed back to the compression process. The throttling process is then carried out in stages. Similarly compression process is also done in two separate compressor stages.

U.K., USA and GERMANY RESPECTIVELY.

U.K., USA and Germany respectively.

ENGINE to burn lean mixture uses HIGH compression ratio and the HIGHLY turbulent movement of the charge is PRODUCED by the geometry of the COMBUSTION chamber.

Engine to burn lean mixture uses high compression ratio and the highly turbulent movement of the charge is produced by the geometry of the combustion chamber.

Thermal N is HIGH for weak mixture and it DECREASES as mixture strength becomes RICH.

Thermal n is high for weak mixture and it decreases as mixture strength becomes rich.

In two-stroke ENGINE lub oil is mixed with petrol and thus some lub oil is blown out through the exhaust valves by SCAVENGING and charging air. There is no such WASTAGE in four stroke petrol engine.

In two-stroke engine lub oil is mixed with petrol and thus some lub oil is blown out through the exhaust valves by scavenging and charging air. There is no such wastage in four stroke petrol engine.

Glycerine has BOILING POINT of 90°C which increases its HEAT CARRYING capacity. Thus weight of coolant gets REDUCED and smaller radiator can be used.

Glycerine has boiling point of 90°C which increases its heat carrying capacity. Thus weight of coolant gets reduced and smaller radiator can be used.

HUCR is highest USEFUL COMPRESSION ratio at which the fuel can be used in a SPECIFIC test engine, under SPECIFIED operating conditions, without KNOCKING.

HUCR is highest useful compression ratio at which the fuel can be used in a specific test engine, under specified operating conditions, without knocking.

For effective lubrication, lub OIL NEEDS to be injected between two PISTON rings when piston is at BOTTOM of stroke so that piston RIDES in oi during upward movement. This way lot of lub oil can be saved and used properly.

For effective lubrication, lub oil needs to be injected between two piston rings when piston is at bottom of stroke so that piston rides in oi during upward movement. This way lot of lub oil can be saved and used properly.

In gas turbines, 70% of the output of gas turbine is consumed by COMPRESSOR. I.C. engines have much lower AUXILIARY consumption. Further combustion TEMPERATURE of I.C. engines is much higher COMPARED to gas turbine.

In gas turbines, 70% of the output of gas turbine is consumed by compressor. I.C. engines have much lower auxiliary consumption. Further combustion temperature of I.C. engines is much higher compared to gas turbine.

HIGH temperature in I.C. engine can be TOLERATED because it lasts for a FRACTION of second but GAS turbines have to face it continuously which metals can't withstand.

High temperature in I.C. engine can be tolerated because it lasts for a fraction of second but gas turbines have to face it continuously which metals can't withstand.

Critical temperature is the MAXIMUM temperature of a REFRIGERANT at which it can be condensed into liquid and BEYOND this it REMAINS GAS irrespective of pressure applied.

Critical temperature is the maximum temperature of a refrigerant at which it can be condensed into liquid and beyond this it remains gas irrespective of pressure applied.

A high latent heat of vaporization of refrigerant RESULTS in SMALL amount of refrigerant and THUS LESSER CIRCULATION system of refrigerant for same tonnage.

A high latent heat of vaporization of refrigerant results in small amount of refrigerant and thus lesser circulation system of refrigerant for same tonnage.

A volatile LIQUID will BOIL under the proper CONDITIONS and in so doing will ABSORB heat from SURROUNDING objects.

A volatile liquid will boil under the proper conditions and in so doing will absorb heat from surrounding objects.

PURGING ensures that any unburnt FUEL in FURNACE is removed, OTHERWISE it may lead to explosion.

Purging ensures that any unburnt fuel in furnace is removed, otherwise it may lead to explosion.

HIGH drum LEVEL does not allow steam separation to be EFFECTIVE and some water can be CARRIED over with steam which is not desirable for steam TURBINE.

High drum level does not allow steam separation to be effective and some water can be carried over with steam which is not desirable for steam turbine.

ELLIPTICAL SHAPE has minimum area of OPENING and thus PLATE is weakened the least. Further it is very convenient to insert and take out the COVER plate from elliptical opening.

Elliptical shape has minimum area of opening and thus plate is weakened the least. Further it is very convenient to insert and take out the cover plate from elliptical opening.

Super-critical PRESSURE BOILER.

Super-critical pressure boiler.

Water tube boilers raise steam fast because of large heat transfer area and positive water circulation. Thus they RESPOND faster to FLUCTUATIONS in demand. Further single tube failure does not lead to CATASTROPHE.

Water tube boilers raise steam fast because of large heat transfer area and positive water circulation. Thus they respond faster to fluctuations in demand. Further single tube failure does not lead to catastrophe.

Safety VALVE should be BLOWN off periodically so that no corrosion can take PLACE on valve and valve seat.

Safety valve should be blown off periodically so that no corrosion can take place on valve and valve seat.

ACID and OXYGEN in feed WATER LEAD to corrosion.

Acid and oxygen in feed water lead to corrosion.

Hard water contains excess of scale FORMING IMPURITIES and SOFT water contains very little or no scale forming SUBSTANCES.

Hard water contains excess of scale forming impurities and soft water contains very little or no scale forming substances.

Sulphates and chlorides of LIME and magnesium form HARD scale, and CARBONATES of lime and magnesium form SOFT scale.

Sulphates and chlorides of lime and magnesium form hard scale, and carbonates of lime and magnesium form soft scale.

It is the actual physical change in METAL that makes it extremely brittle and filled with minute CRACKS. It occurs particularly in the seams of riveted joints and AROUND the rivet HOLES.

It is the actual physical change in metal that makes it extremely brittle and filled with minute cracks. It occurs particularly in the seams of riveted joints and around the rivet holes.

NON uniform corrosion over the entire metal SURFACE, but OCCURRING only in SMALL pits is called pitting. It is CAUSED by lack of uniformity in metal.

Non uniform corrosion over the entire metal surface, but occurring only in small pits is called pitting. It is caused by lack of uniformity in metal.

Anergy.

Anergy.

ISENTROPIC efficiency of AXIAL FLOW compressor is HIGHER.

Isentropic efficiency of axial flow compressor is higher.

The maximum power is consumed at about 70% of maximum flow in case'of FAN with backward blades. For HIGHER flow, power consumption GETS lower.

The maximum power is consumed at about 70% of maximum flow in case'of fan with backward blades. For higher flow, power consumption gets lower.

Stalling is a LOCAL PHENOMENON and it occurs when How breaks away from the BLADES. Surging CAUSES complete breakdown of flow and as such it affects the whole machine.

Stalling is a local phenomenon and it occurs when How breaks away from the blades. Surging causes complete breakdown of flow and as such it affects the whole machine.

It is LEAST when compression PROCESS approaches isothermal. For this PURPOSE, attempts are made to COOL the air during compression.

It is least when compression process approaches isothermal. For this purpose, attempts are made to cool the air during compression.

At the CRITICAL PRESSURE RATIO.

At the critical pressure ratio.

Zero.

Zero.

COP of HEATING is ONE(UNITY) more than COP of COOLING.

COP of heating is one(unity) more than COP of cooling.

Nil

Nil