5. THERMAL ENERGYFuel: Fuel is a combustible substance, containing carbon as main constituent, which on proper burning, gives large amount of heat, which can be used for domestic and industrial purposes.

CombustionFuel + O2 -------------------> Products + Heat.

This process is known as “Combustion”.

Classification of Fuels:Fuels can be classified on the basis of their occurrence and state of aggregation. On the basis of occurrence, fuels are classified into two types.

a) Natural Fuels (or) Primary Fuels: These are found in nature as such Eg:- Wood, coal, petroleum, natural gas etc., and

b) Secondary Fuels (Or) Derived Fuels: These are prepared from the primary fuels Eg:- Charcoal, coke, kerosene, diesel, petrol, Coal gas, producer gas etc.,

On the basis of State of Aggregation, fuel can again be classified into:

Fuels

Natural Derived(Primary) (Secondary)

Solid Liquid Gaseous Solid Liquid Gaseous(Wood, (Crude Oil, (Natural Gas) (Coke, (Kerosene, (Coal gas,Coal, Petroleum) Charcoal, Water gas,Peat, Petroleum- Cokeoven)Dung) Coke)

Relative merits of solid, liquid and gaseous fuels:

S.No. Solid fuels Liquid fuels Gaseous fuels1. Easily available and

inexpensiveCostlier than solid fuels Except natural gas, others

are costly.2. Transportation is easy and

cheap, without any risk.Can be transported through pipelines.

Care must be taken during transport and storage.

3. Combustion is slow Combustion is fast Combustion is rapid.4. Ash is produced after

combustionNo ash No ash

5. Cannot be used in IC engines Can be used in IC engines Can be used in IC engines6. Require large excess of air for

combustion. Require less air. Require less air

7. Thermal efficiency is least Moderate Highest

CALORIFIC VALUE:The efficiency of a fuel is measured by its calorific value and is defined as“The total amount of heat liberated when a unit mass (or volume) of the fuel is burnt completely”.

Units of heat: 1) Calorie: It is the amount of heat required to raise the temperature of 1 gm of water through 10C.

1 Calorie = 4.185 Joules = 4.185×107 ergs.2) Kilocalorie: It is the amount of heat required to raise the temperature of 1Kg of water through 1oC.

1 Kilocalorie = 1000 Calories.3) British Thermal Unit (B.T.U):- It is the amount of heat required to raise the temperature of one pound (1 lb)of water through 1o F.

1 B.T.U = 252 calories.4) Centigrade heat unit (C.T.U):- It is the amount of heat required to raise the temperature of one pound (1 lb) of water through 1oC.

1 K.Cal = 3.968 B.T.U. = 2.2 CHU

Higher or Gross calorific value(GCV or HCV):The Gross Calorific Value (or) High Calorific value is heat liberated when a unit quantity of fuel is completely burnt and the products of combustion are cooled to room temperature. This heat includes the latent heat ofcondensation of water. Because when a fuel containing hydrogen is burnt, the hydrogen present is converted to steam. As the products of combustion are cooled to room temperature, the steam gets condensed into water and the latent heat is evolved. Thus the latent heat of condensation of steam, so liberated, is included in the Gross Calorific Value.

Low (or) Net calorific value (LCV):The Net Calorific Value (or) Low calorific value is the net heat produced when a unit quantity of fuel is completely burnt and the products of combustion are allowed to escape.

LCV = HCV – latent heat of water vapour formed.

CHARACTERISTICS OF GOOD FUEL:The following factors are of prime importance while selecting a good fuel. i) High calorific value: The amount of heat liberated depends upon the calorific value

of a fuel. Hence, a good fuel should have a higher calorific value.ii) Moderate Ignition temperature:

Ignition temperature: The temperature at which a solid, liquid and a gaseous fuel catches fire and burns continuously without further heating is called ignition temperature. Low ignition temperature is dangerous for storage and transport of fuel. Since it can cause fire hazards, on the other hand high ignition temperature causes difficulty in igniting the fuel, but the fuel is safe during transport, handling and storage. Hence, an ideal fuel should have a moderate ignition temperature.

iii) Low moisture content: Greater quantity of moisture in the fuel decreases its calorific value. Hence, a good fuel should have low moisture content.

iv) Low Non-Combustible matter content: A good fuel should have low non-combustible matter content because it reduces the heating value, besides additional cost of storage and handling.

v) Moderate Velocity of Combustion: A good fuel should have a moderate velocity of combustion. If the rate of combustion is low, then the required temperature may not be attained because a part of the heat liberated may get radiated instead of raising the temperature.

vi) Combustion products should not be harmful: The gases formed during the process of combustion should not be harmful to the living beings and should not pollute the atmosphere. CO, SO2, H2S are some of the harmful gases.

vii) A good fuel is one which can be handled, stored and transported easily and at low cost. It should also be available in bulk and at a cheaper rate.

ANALYSIS OF COAL:Coal is analysed in two ways depending on the data required. 1) Proximate Analysis: In this analysis records Moisture, Volatile Matter, Ash and Fixed Carbon as Percentages of the original weight of coal sample.2) Ultimate Analysis: In this analysis determination of the ultimate constituents in dry coal such as C, H, O, N, S etc., This method is not as useful as the previous one.

PROXIMATE ANALYSIS:i) Moisture: About 1gm. Of finely powdered, air dried coal, taken in a crucible

is heated to 1100C temperature for about 1 Hour in a hot air oven. Loss in weight of the crucible is reported as moisture.

Percentage of moisture = Loss in weight________ X 100Weight of Coal sample taken

ii) Volatile Matter: The dried sample of coal left in the crucible in (i) is covered with a lid and heated in an electric furnace, maintained at 9500C + 200C. The heating is done for 7 minutes. At this temperature, hydrocarbons and hydrogen are driven off. The loss in weight of crucible is reported as volatile matter.

Percentage of volatile matter = Loss in weight due to removal of volatile matter X 100Weight of Coal sample taken

iii) Ash: The residual coal in the crucible in (ii) is heated in a muffle furnace at 700-7500C for 30 minutes. The crucible is cooled and weighed. This is continued until a constant weight is obtained. The percentage of ash is calculated as follow. The furnace should not have lid.

Percentage of Ash = _____Weight of ash left_____ X 100Weight of Coal sample taken

iv) Fixed Carbon: Fixed carbon is reported as 100 – (%Moisture + % Volatile Matter + % Ash)

IMPORTANCE (SIGNIFICANCE) OF PROXIMATE ANALYSIS:Proximate analysis furnishes, the following information necessary to assess the usefulness of a coal sample.

a) Moisture: Presence of moisture in coal is objectionable, since moisture in coal evaporates during the burning of coal by absorbing some of the liberated heat in the form of latent heat of evaporation. Therefore, moisture lowers the effective calorific value of coal. ∴ Moisture α 1_________

Efficiency of Coal

b) Volatile Matter: A high percent of volatile matter indicates that a larger proportion of the fuel is converted into gas or vapour and so for the efficient use of fuel, the volatile matter will have to be burnt by supplying secondary air. A large combustion is thus required. A high volatile matter containing coal has a low calorific value. Hence, lesser the volatile matter, better the rank of coal.

∴ Volatile Matter α 1_________ Efficiency of Coal

c) Ash: Ash is a useless, non-combustible matter of coal, which reduces the calorific value of coal. Ash forming constituents in coal are undesirable for the following reasons:

a) Calorific value of coal is reduced.b) Removal and disposal of ash is problem.c) Ash deposited in the fire band stops the circulation of air.d) If the ash fuses with fire bars to form “clinkers”, air circulation is

stopped and also leads to corrosion of fire bars.

∴ Ash content α 1_________ Efficiency of Coal

d) Fixed Carbon: Greater the percentage of fixed carbon, smaller is the percentage of volatile matter and therefore higher calorific value of coal sample. Percentage of fixed carbon, also represents the carbon that can be burnt.

∴ Fixed Carbon α Efficiency of Coal

ULTIMATE ANALYSIS:In this analysis determination of the ultimate constituents in dry coal such as

C, H, N, S, O etc., can be done. This method is not as useful as the Primate Analysis.

i) Determination of Carbon and Hydrogen: A known weight of coal sample is burnt in a steam of oxygen in a combustion apparatus. Carbon and Hydrogen of the coal are converted into CO2 and H2O respectively.

C + O2 CO2

H2 + ½ O2 H2O

The gaseous combustion products are absorbed by KOH and anhydrous CaCl2

tubes of known weights respectively. The increase in weight of tubes is then determined.

2 KOH + CO2 K2CO3 + H2OCaCl2 + H2O CaCl2.H2O

% of C = increase in weight of KOH tube X At. Wt. of C (12) X 100Wt. of coal sample X M.W. of CO2 (44)

% of H = increase in weight of CaCl2 tube X Mol. Wt. of H (2) X 100Wt. of coal sample X M.W. of H2O (18)

ii) Determination of Nitrogen (Kjeldahl’s Metod): A known weight of powdered coal is heated with Conc. H2SO4 and K2SO4 (used as catalyst) in a long-necked flask. If any Nitrogen is present in the coal is converted into Ammonium Sulphate. After the solution becomes clear, it is treated with excess of KOH, and then ammonia is liberated. The liberated ammonia is allowed to absorb in a known volume of standard acid solution. The unused acid is determined by back titration with std. NaOH solution. From the volume of acid consumed by the liberated ammonia, the percentage of nitrogen is calculated.

Coal + H2SO4 ----------> (NH4)2SO4

(NH4)2SO4 + 2KOH ----------> 2NH3 + K2SO4 + 2H2O2NH3 + H2SO4 -------------> (NH4)2SO4

(Acid used)

% of Nitrogen = Vol. of acid used X Normality of acid X 1.4 Wt. of coal sample taken

iii) Determination of Sulphur: A known weight of coal is burnt completely in bomb calorimeter in a current of oxygen, wherein the sulphur present in the coal is oxidized to sulphates. This upon treatment with barium chloride precipitates the sulphate as barium sulphate. The precipitate of BaSO4 is filtered, washed, dried and heated to constant weight.

O2 BaCl2

S -----------> SO42- --------------------> BaSO4

% of Sulphur = weight of BaSO4___________ X 32 x 100Weight of coal sample taken 233

Where 32 is the atomic weight of sulphur and 233 is the molecular weight of barium sulphate.

iv) Determination of Oxygen: It is determined indirectly by deducting the combined percentage of Carbon, Hydrogen, Nitrogen, Sulphur and Ash content from 100.% of Oxygen is reported as 100 – {%C + %H + %N + %S + %Ash)

IMPORTANCE (SIGNIFICANCE) OF ULTIMATE ANALYSIS:

a) Carbon and Hydrogen: The percentage of carbon forms the basis of classification of coal. Greater the percentage of carbon & hydrogen, higher is the calorific value of coal sample. However, hydrogen is mostly associated with volatile matter, and hence excess of hydrogen lowers the rank of coal.

b) Nitrogen: Nitrogen does not contribute to calorific value. So its presence in coal is undesirable. Thus, a good quality coal should have very low percentage of nitrogen.

c) Sulphur: It is an undesirable constituent of coal. When coal is burnt, sulphur compounds produce SO2 and SO3 which pollute the atmosphere, and the sulphuric acid formed in aqueous environments leads to corrosion of equipment.

d) Oxygen: High oxygen-content coals are characterized by high inherent moisture, low calorific value and low coking power. 1% increase in oxygen content decreases the calorific value of coal by about 1.7%. Hence, oxygen is undesirable.

PULVARISED COAL:The combustion rate of solid fuels, like coal is generally slow, because of the difficulty of thorough contact between the solid fuel and atmospheric oxygen. The combustion rate may be increased, by increasing the rate of oxygen supply, but this method involves a wastage of large proportion of heat carried by air itself.

So a better method is pulverization of coal. By pulverization (finely powdering), the surface area of fuel is increased and fuel burns more rapidly. Pulverisation method is more satisfactory for volatile coals. The volatile matter present in the coal is liberated quickly, thereby helping the burning of fixed carbon.

Advantages of Pulverisation:• It can be easily transported• The rate of combustion can be controlled by controlling the quantity of coal

powder.• The pulverized coal can be stored easily.• Long flame is produced resulting in the development of uniform temperature.• Low labour charges for handling.• Low grade and high ash coal can be used satisfactorily.• It is useful for metallurgical purpose.• Small percentage of excess air for sufficient for complete combustion.• Higher thermal efficiency and higher temperature.

CARBONIZATION OF COAL:

Coal (Primary Solid fuel), on suitable treatment, gives secondary solid fuels like coke and semi-coke, liquid fuels like coaltar and hydrogenated coal and gaseous fuels like watergas, producer gas etc.,

“The decomposition of coal by heating it in the absence of air (destructive distillation) to give a solid residue, coke is called CARBONIZATION”.

There are two types of carbonization of coal.

1) Low Temperature Carbonisation: In this process coal is heated to a temperature not exceeding 6500C. The yield of coke is about 75-80% and contains about 5-15% volatile matter. The coke cannot be used for metallurgical purpose because of its low mechanical strength. It burns easily giving smokeless, hot and radiant fire. Hence, it is suitable for domestic purposes. The by-product gas produced has a calorific value of about 6500-9500 K.Cal / m3 and is therefore, a more valuable gaseous fuel.

2) High Temperature Carbonsation: This is carried out at temperature of 10000C or more, nearly all the volatile matter of coal is driven-off (approximately 1-3% remains), and the yield of coke is 65-75%. The coke produced is hard and is of good mechanical strength. So, it is suitable for metallurgical purposes. The by-product gas produced had a calorific value of about 5400-6000 K.Cal/m3.

Differences between low and high temperature carbonization:

Sl.No.

Low temperature carbonization High temperature carbonisation

1 Heating temperature will be around 500-7000C 900-12000C2 Yield of the product is 75-80% 65-75%3 Percentage of Volatime Matter is 5-15% 1-3%4 Not mechanically strong Mechanically strong5 Good for domestic purpose Good for metallurgy6 Quantity of the byproduct gas = 130-150 m3/tonne 300-390 m3 / tonne7 CV of the by product gas 6500-9500 K.Cal / m3 5400-6000 K.Cal / m3

8 Soft coke is produced Hard coke is produced9 Smokeless coke Smoky coke10 Has low aromatic and high straight chain

hydrocarbonsHas high aromatic and low straight chain hydrocarbons

MANUFACTURE OF METALLURGICAL COKE:

The coke for metallurgical purpose is obtained by two methods.

A) BEE-HIVE OVEN:B) OTTO HOFFMAN’S BY-PRODUCT OVEN:

A) BEE-HIVE OVEN:It is the earliest and cheapest process for manufacturing metallurgical coke.

The beehive oven is a dome-shaped structure of bricks. The oven is provided with two openings, one at the top, for charging coal and the other at one side for air supply as well as for coke discharge.

The oven is charged with coal and leveled to produce a layer about 0.6m deep. Some air is let in and the coal is ignited. The volatile matter is driven off through the

side door. Combustion is allowed to proceed in a gradually diminishing supply of air, so that, slow carbonization takes place from top. The coal is carbonized by the heat radiated on to the surface of oven, and the coking action is thus downwards. When the carbonization is complete, the hot coke is quenched with water and raked out through the side door. The yield of coke is about 80% of the coal charged.

OTTO HOFFMAN’S BY-PRODUCT OVEN:

This process is dependent on the utilizing the waste flue gases for heating the brickwork. (Regenerative principle of heat economy). In this process the thermal efficiency is increased and valuable by-products (i.e., Ammonia, Benzene, Naphthalene, Tar, H2S etc.,) are recovered.

The coke oven consists of a number of narrow silica chambers erected side by side with vertical flues in between them. Each chamber is provided with a charring hole at the top. It is made up of refratory lining. And cast iron door at each ends for discharging coke.

Finally crushed coal is introduced through the holes present at the top of the chambers, which are then closed tightly at both the ends to prevent any access of air. The coke ovens are heated at 12000C by burning gaseous fuel like producer gas. The flue gases which are produced during combustion, pass on their sensible heat to one of the two sets of chambers to raise the temperature of about 10000C. The flow of heating gases is then reversed to heat other set of bricks. Thus, this cycle will be repeated.

The heating is actually continued, till the evolution of volatile matter ceases completely. The process of carbonization takes place for about 11 to 18 hours.

After the completion of carbonization, a ram pushes the red hot coke into a truck which is quenched by a water spray.

Recovery of By-products: Coke oven gas and is mainly composed of NH3, H2S, Naphthalene, Benzene, tar and moisture.

(Petroleum ether)

Tar

(Benzene)

1) Recovery of Tar: The gas is first passed through a tower in which liquor ammonia is sprayed. Here dust and tar get collected in a tank below, which is heated by steam coils to recover back ammonia sprayed. The ammonia is used again.

2) Recovery of ammonia: The gases from the chamber are then passed into a tower in which water is sprayed. Ammonia dissolves in water to form ammonium hydroxide.

3) Recovery of naphthalene: The gases are allowed to pass into another tower in which water at very low temperatures sprayed such that the naphthalene is condensed.

4) Recovery of Benzene: The gases are then sprayed with petroleum ether to recover benzene.

5) Recovery of H 2S: To recover hydrogen sulphide, the gases are allowed to pass through moist Fe2O3.

OHSFeSHOFe 232232 33 +→+

2232 324 SOFeOOSFe +→+

322 24 OFeOFeO →+THERMAL POWER STATION:

A Power Station is an industrial facility for the generation of electric power. Power stations has a generator, a rotating machine that converts mechanical energy into electrical energy by creating relative motion between a magnetic filed and a conductor.

In thermal power stations, mechanical power is produced by a heat engine that transforms thermal energy, often from combustion of a fuel into rotational energy. IN thermal generating stations coal, oil and natural gas are employed as primary sources of energy.

Coal Stocker: The coal which is brought near by boiler has to put in boiler furnace for combustion. This stocker is a mechanical device for feeding coal to a furnace.

Coal Conveyor: This is a belt type of arrangement. With this coal is transported from coal storage place in power plant to the place near by boiler.

Pulverised mill: The coal is put in the boiler after pulverization. For this purpose, the pulveriser is used. A pulveriser is a device for grinding coal for combustion in a furnace in a power plant.

Boiler: Now that pulverized coal is put in boiler furnace. Boiler is an enclosed vessel in which water is heated and circulated until the water is turned into steam at the required pressure . Coal is burnt inside the combustion chamber of boiler. The products of combustion are nothing but gases. These gases which are at high temperature vaporize the water inside the boiler to steam. Some times this steam is further heated in a super heater as higher the steam pressure and temperature the greater efficienty the engine will have in converting the heat in steam into mechanical work. Water taken in boiler is common because of its economy and suitable thermodynamic characteristics.

Superheater: Most of the modern boilers are having super heater and reheater arrangement. Superheater is a component of a steam-generating unit in which steam, after it has left the boiler drum, is heated above its saturation temperature. Super heaters are classified as convection, radiant or combination of these two.

Reheater: Some of the heat of superheated steam is used to rotate the turbine where it loses some of its energy. Reheater is also steam boiler component in which heat is added to this intermediate-pressure steam, which has given up some of its energy in expansion through the high-pressure turbine. The steam after reheating is used to rotate the second steam turbine where the heat is converted to mechanical energy.

Economiser: Flue gases coming out of the boiler carry lot of heat. Function of economizer is to recover some of the heat from the heat carried away in the flue gases up the chimney and utilize for heating the feed water to the boiler. It is placed in the passage of flue gases in between the exit from the boiler and the entry to the chimney. The use of economizer results in saving in coal consumption, increase in steaming rate and high boiler efficiency.

Air preheater: The remaining heat of flue gases is utilized by air preheater. It is a device used in steam boilers to transfer heat from the flue gases to the combustion air before the air enters the furnace, it is also known as air heater.

Deaerator: A steam generating boiler requires that the boiler feed water should be devoid of air and other dissolved gases, particularly corrosive ones, in order to avoid corrosion of the metal. Generally, power stations use a deaerator to provide for the removal of air and other dissolved gases from the boiler feed water.

Prime Movers: In case of coal fired plants, steam is produced in the boiler is passed through an axial flow turbines (Prime movers).

Condenser: Steam after rotating “steam turbine” comes to condenser. These condensers are heat exchangers which convert steam from its gaseous to its liquid state. The purpose is to condense the outlet steam from steam turbine to obtain maximum efficiency and also to get the condensed steam in the form of pure water, back to boiler as boiler feed water.

Cooling Towers: The water formed in the condenser after condensation is initially at high temperature. This hot water is passed to cooling towers. It is a device in which atmospheric air circulates in direct or indirect contact with warm water and the water is thereby cooled.

Electrostatic Precipitator: It is a device which removes dust or other finely divided particles from flue gases by charging the particles inductively with an electric field, then attracting them to highly charged collector plates.

Smoke Stack: A chimney is a system for venting hot flue gases or smoke from a boiler, stove, furnace or fireplace to the outside atmosphere.Generator: A generator is an electromechanical device that converts mechanical energy to alternating current electrical energy by using a rotating magnetic field.

Transformers: It is a device that transfers electric energy from one A.C. Circuit to one or more other circuits, either increasing (stepping up) or reducing (stepping down) the voltage.

Monitoring and alarm system: Most of the power plant operational controls are automatic. However, at times, manual intervention may be required. Thus, the plant is provided with monitors and alarm systems that alert the plant operators when certain opening parameters are seriously deviating from their normal stage.

Battery supplied for emergency lighting and communication: A central battery system consisting of lead acid cell units is provided to supply emergency electric power, when needed to essential items such as the power plant’s control systems, communication systems.

Control Room and Switchyard: The control room monitors the overall operation of the plant. It is provided with controls for real and reactive power flow. It is provided with safety relays and switchgears.

BOMB CALORIMETER:

Principle: A known weight of fuel is completely burnt in a bomb calorimeter and the net rise in temperature of known weight of water in the calorimeter is measures. From this the calorific value can be calculated.

Construction: It consists of a strong cylindrical stainless steel bomb in which the combustion of the fuel will take place. The bomb has a lid which can be screwed to the body of the bomb so as to make it gas tight. The lid is provided with two stainless steel electrodes and an oxygen inlet valve. To one of the electrode, a small ring is attached on which a stainless steel crucible is kept. The bomb is placed in a copper calorimeter which is surrounded by a water jacket and an air jacket for preventing the loss of heat due to radiation. The calorimeter is provided with a stirrer and a Beckmann’s Thermometer.

Working: About 0.5g to 1.0 g of the given fuel is taken in a crucible which is supported over the ring. A fine magnesium (or) platinum wire touching the fuel sample is then stretched across the electrodes. The bomb lid is tightly screwed and bomb is filled with oxygen to its atmospheric pressure. The bomb is then lowered into copper calorimeter, containing a known mass of water. The stirrer is worked and initial temperature of the water is noted. The electrodes are then connected to a 6 volt battery. The sample burns and heat is liberated. Uniform stirring of water is continued and maximum temperature attained is recorded.

Calculation: Let m = Mass in ‘g’ of fuel sample taken in crucible;

W = Mass of water in the calorimeter;w = Water equivalent in ‘g’ of calorimeter, stirrer, thermometer etc;t1 = initial temperature of water in calorimeter, t2 = final temperature of water in calorimeter.L = Higher calorific value of fuel in cal/g;∴ Heat liberated by burning of fuel = mLHeat absorbed by water and apparatus = (W+w) (t2-t1).

But, Heat liberated by burning of fuel = Heat absorbed by water and apparatus∴ mL = (W+w) (t2-t1)

Higher Calorific value of fuel (or) L = (W+w) (t2-t1) m(The Water equivalent of calorimeter is determined by burning a fuel of known calorific value and using the above equation).

If H = percentage of hydrogen in fuel, then, 9H/100g = mass of H2O from 1g of fuel= 0.09H g.

∴ Heat taken by water to forming steam = (0.09H×587) cal/g(Since latent heat of steam = 587 cal/g)

∴ LCV= HCV-latent heat of water formed = HCV- 0.09H×587 cal/gCorrections: To obtain accurate results certain corrections should be made.1. Fuse wire correction: The heat liberated in the above process involves the liberated due to the ignition of fuse wire. Hence, it must be subtracted from the total value.2. Acid correction: Many fuels contain some “S” , “N” and “H”. Under high temperature and pressure, these get oxidized to form H2SO4 and HNO3. Formation of these acids is exothermic. So this liberated heat should also be considered and subtracted from the experimentally determined calorific value. 1) 2S + 3O2 2SO3; 2H2 + O2 2H2O; H2O + SO3 H2SO4;2) N2 + 2O2 2NO2; 2H2 + O2 2H2O; 4NO2 + 2H2O +O2 4HNO3;3. Cooling correction: Due to stirring and evaporation loss of heat may be observed. This correction is generally little and is ignored. It can be measured by the water is allowed to cool down from the maximum temperature to a low temperature and the time taken (t) and the rate of cooling (dt) noted. The correction (t x dt) is then added to the rise in temperature and calculation done to obtain the correct calorific value. Hence,

H.C.V (L) = (W+w) (t2-t1+cooling correction)-(acid correction+ fuse wire correction)Mass of the fuel (m)