Tar is a better fuel than furnace oil, because of its (A) Higher calorific value (B) Lower sulphur content (C) Higher emissivity (0.8-0.9) resulting in higher radiation heat transfer rate (D) Both (A) and (B)

Tar is a better fuel than furnace oil, because of its
(A) Higher calorific value
(B) Lower sulphur content
(C) Higher emissivity (0.8-0.9) resulting in higher radiation heat transfer rate
(D) Both (A) and (B)
by

1 Answer

Answer :

(D) Both (A) and (B)
by

Related questions

Pitch creosote mixture (PCM) as compared to furnace oil is a better fuel, because its (A) Emissivity factor is higher (B) Sulphur content is lower (C) Flue gas has lower dew point thereby facilitating more waste heat recovery (D) All (A), (B) and (C)

Description : Pitch creosote mixture (PCM) as compared to furnace oil is a better fuel, because its (A) Emissivity factor is higher (B) Sulphur content is lower (C) Flue gas has lower dew point thereby facilitating more waste heat recovery (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Coal tar fuels (CTF) as compared to petroleum based fuel oils have higher (A) Calorific value (B) Higher C/H ratio (C) Sulphur content (D) Difference in gross & net calorific value

Description : Coal tar fuels (CTF) as compared to petroleum based fuel oils have higher (A) Calorific value (B) Higher C/H ratio (C) Sulphur content (D) Difference in gross & net calorific value

Last Answer : (B) Higher C/H ratio

Coke oven gas is a better fuel than blast furnace gas, because of its higher (A) Calorific value, cleanliness and relatively low distribution cost (due to its low specific gravity) (B) Adiabatic flame temperature (C) Heat release rate (thus requiring smaller combustion chamber) (D) All (A), (B) and (C)

Description : Coke oven gas is a better fuel than blast furnace gas, because of its higher (A) Calorific value, cleanliness and relatively low distribution cost (due to its low specific gravity) (B) Adiabatic flame temperature ... release rate (thus requiring smaller combustion chamber) (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Which of the following is not increased by using preheated combustion air in place of ordinary air at room temperature? (A) Calorific value of the fuel (B) Flame temperature achieved (C) Speed of combustion of fuel (D) Heat transfer rate to the stock in the furnace

Description : Which of the following is not increased by using preheated combustion air in place of ordinary air at room temperature? (A) Calorific value of the fuel (B) Flame temperature achieved (C) Speed of combustion of fuel (D) Heat transfer rate to the stock in the furnace

Last Answer : (A) Calorific value of the fuel

Calculate the rate of heat transfer by radiation from an unlagged steam pipe, 50 mm o.d. at 393K to air at 293K emissivity e = 0.9.

Description : Calculate the rate of heat transfer by radiation from an unlagged steam pipe, 50 mm o.d. at 393K to air at 293K emissivity e = 0.9.

Last Answer : Rate of heat transfer by radiation Assume length of pipe = 1 m

LSHS is a type of furnace oil, which (A) Is more viscous than high viscosity furnace oil (HVFO) (B) Stands for low sulphur heavy stock (C) Is an ideal fuel for metallurgical furnaces due to its lower sulphur content (< 1%(D) All (A), (B) and (C))

Description : LSHS is a type of furnace oil, which (A) Is more viscous than high viscosity furnace oil (HVFO) (B) Stands for low sulphur heavy stock (C) Is an ideal fuel for metallurgical furnaces due to its lower sulphur content (< 1%) (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

All heat engines utilize a. lower heating value of oil b. higher heating value of oil c. net calorific value of oil d. calorific value of fuel

Description : All heat engines utilize a. lower heating value of oil b. higher heating value of oil c. net calorific value of oil d. calorific value of fuel

Last Answer : ANSWER a. lower heating value of oil

Heat transfer rate to the charge/stock in a furnace does not depend upon the (A) Type of fuels viz. solid, liquid or gaseous (B) Flue gas temperature (C) Emissivity of refractory walls (D) Initial temperature of the charged stock

Description : Heat transfer rate to the charge/stock in a furnace does not depend upon the (A) Type of fuels viz. solid, liquid or gaseous (B) Flue gas temperature (C) Emissivity of refractory walls (D) Initial temperature of the charged stock

Last Answer : (A) Type of fuels viz. solid, liquid or gaseous

Heat transfer rate to the stock/charge in the furnace does not depend upon the(A) Emissivity of the refractory walls(B) Size of the furnace(C) Use of waste heat recovery equipments(D) Thickness of the stock

Description : Heat transfer rate to the stock/charge in the furnace does not depend upon the (A) Emissivity of the refractory walls (B) Size of the furnace (C) Use of waste heat recovery equipments (D) Thickness of the stock

Last Answer : (C) Use of waste heat recovery equipments

In high temperature carbonisation of coal compared to low temperature carbonisation (A) Yield of ammonia is less (B) Aromatic content of tar is low (C) H2 content in the coke oven gas is more (D) Calorific value of the coke oven gas is lower

Description : In high temperature carbonisation of coal compared to low temperature carbonisation (A) Yield of ammonia is less (B) Aromatic content of tar is low (C) H2 content in the coke oven gas is more (D) Calorific value of the coke oven gas is lower

Last Answer : (C) H2 content in the coke oven gas is more

Pitch (a product of coal tar distillation) is always mixed with creosote oil, when it is to be burnt in a burner, because (A) Its calorific value is very less (B) Tar neutralises the residual acids present in pitch (C) It reduces viscosity and imparts fluidity for its transportation through pipelines at economic pressure drop (D) All (A), (B) and (C)

Description : Pitch (a product of coal tar distillation) is always mixed with creosote oil, when it is to be burnt in a burner, because (A) Its calorific value is very less (B) Tar neutralises the residual acids ... for its transportation through pipelines at economic pressure drop (D) All (A), (B) and (C)

Last Answer : (C) It reduces viscosity and imparts fluidity for its transportation through pipelines at economic pressure drop

Out of the following fuels, the difference between the net and gross calorific value is maximum in case of (A) Pitch (B) Fuel oil (C) Blast furnace gas (D) Bituminous coal

Description : Out of the following fuels, the difference between the net and gross calorific value is maximum in case of (A) Pitch (B) Fuel oil (C) Blast furnace gas (D) Bituminous coal

Last Answer : (B) Fuel oil

A liquid/gaseous fuel containing hydrocarbons and high amount of sulphur is burnt with 40% excess air. The flue gas still contains large amount of carbon monoxide. This may be due to the (A) Presence of large quantity of hydrogen in the fuel (B) Low calorific value of the fuel (C) High sulphur content in the fuel (D) Lack of thorough mixing of fuel with air

Description : A liquid/gaseous fuel containing hydrocarbons and high amount of sulphur is burnt with 40% excess air. The flue gas still contains large amount of carbon monoxide. This may be due to the (A) Presence of large ... fuel (C) High sulphur content in the fuel (D) Lack of thorough mixing of fuel with air

Last Answer : (D) Lack of thorough mixing of fuel with air

The optimum percentage of excess air for combustion depends upon the__________ of the fuel.(A) Type (solid, liquid or gaseous)(B) Calorific value(C) Sulphur content(D) Ignition temperature

Description : The optimum percentage of excess air for combustion depends upon the__________ of the fuel. (A) Type (solid, liquid or gaseous) (B) Calorific value (C) Sulphur content (D) Ignition temperature

Last Answer : (A) Type (solid, liquid or gaseous)

Blast furnace gas compared to coke oven gas has (A) Lower ignition temperature (B) Narrower limit of inflammability (C) Higher calorific value (D) Lower theoretical flame temperature

Description : Blast furnace gas compared to coke oven gas has (A) Lower ignition temperature (B) Narrower limit of inflammability (C) Higher calorific value (D) Lower theoretical flame temperature

Last Answer : (D) Lower theoretical flame temperature

Which of the following is not an important property of fuel oil/furnace oil? (A) Sulphur content (B) Viscosity (C) Aniline point (D) Flash point

Description : Which of the following is not an important property of fuel oil/furnace oil? (A) Sulphur content (B) Viscosity (C) Aniline point (D) Flash point

Last Answer : (C) Aniline point

The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by (A) Painting the surface black (B) Painting the surface white (with aluminium paint) (C) Giving the surface a mirror finish (D) Roughening the surface

Description : The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by (A) Painting the surface black (B) ... white (with aluminium paint) (C) Giving the surface a mirror finish (D) Roughening the surface

Last Answer : (B) Painting the surface white (with aluminium paint)

reduction in thermal resistance during heat transfer does not occur in the (A) Convection heat transfer by stirring the fluid and cleaning the heating surface (B) Conduction heat transfer by reduction in the material thickness and increase in the thermal conductivity (C) Radiation heat transfer by increasing the temperature and reducing the emissivity (D) None of these

Description : reduction in thermal resistance during heat transfer does not occur in the (A) Convection heat transfer by stirring the fluid and cleaning the heating surface (B) Conduction heat transfer by ... Radiation heat transfer by increasing the temperature and reducing the emissivity (D) None of these

Last Answer : Option C

Coke oven gas produced by high temperature carbonisation of coal (as compared to that produced by low temperature carbonisation), has (A) Higher calorific value (B) Lower hydrogen content (C) Both (A) and (B) (D) Neither (A) nor (B)

Description : Coke oven gas produced by high temperature carbonisation of coal (as compared to that produced by low temperature carbonisation), has (A) Higher calorific value (B) Lower hydrogen content (C) Both (A) and (B) (D) Neither (A) nor (B)

Last Answer : (D) Neither (A) nor (B)

In low temperature carbonisation of coal as compared to high temperature carbonisation __________ produced is less. (A) Difference in gross & net calorific value of the coke oven gas (B) Free carbon content in tar (C) Yield percentage of coke (D) Yield of ammonia present in coke oven gas

Description : In low temperature carbonisation of coal as compared to high temperature carbonisation __________ produced is less. (A) Difference in gross & net calorific value of the coke oven gas (B) Free carbon content in tar (C) Yield percentage of coke (D) Yield of ammonia present in coke oven gas

Last Answer : (A) Difference in gross & net calorific value of the coke oven gas

Pick out the wrong statement. (A) Aromatics have higher specific gravity than paraffins (B) Gross calorific value (GCV) of petrofuels is equal to (12400 - 2100 ρ 2 ) where, ρ is the specific gravity of the fuel at 15.5°C (C) Heavier petrofuels have higher GCV on weight basis (i.e., Kcal/kg) but lower GCV on volume basis (i.e., Kcal/litre) (D) Higher specific gravity of petrofuels means higher C/H ratio

Description : Pick out the wrong statement. (A) Aromatics have higher specific gravity than paraffins (B) Gross calorific value (GCV) of petrofuels is equal to (12400 - 2100 ρ 2 ) where, ρ is the specific gravity ... volume basis (i.e., Kcal/litre) (D) Higher specific gravity of petrofuels means higher C/H ratio

Last Answer : (C) Heavier petrofuels have higher GCV on weight basis (i.e., Kcal/kg) but lower GCV on volume basis (i.e., Kcal/litre)

Calorific value of (A) Light paraffinic fuel oils is equal to that of equivalent olefins (B) n-paraffin is lower than that of iso-paraffins of the same compounds (C) Light paraffinic fuel oils is higher than that of equivalent olefins (D) Light paraffinic fuel oils is lower than that of equivalent olefins

Description : Calorific value of (A) Light paraffinic fuel oils is equal to that of equivalent olefins (B) n-paraffin is lower than that of iso-paraffins of the same compounds (C) Light paraffinic fuel ... than that of equivalent olefins (D) Light paraffinic fuel oils is lower than that of equivalent olefins

Last Answer : (C) Light paraffinic fuel oils is higher than that of equivalent olefins

In a furnace, the heat taken by the charge/stock and the heat lost to the furnace structure & flue gases depends on the (A) Rate of firing and emissivity of flame (B) Thermal conductivity of the charge & structural materials of furnace (C) Nature of process; whether batch, continuous or intermittent (D) All (A), (B) and (C)

Description : In a furnace, the heat taken by the charge/stock and the heat lost to the furnace structure & flue gases depends on the (A) Rate of firing and emissivity of flame (B) Thermal conductivity of the charge & ... (C) Nature of process; whether batch, continuous or intermittent (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Use of pulverised coal in boilers provides (A) Higher calorific value (B) Better combustion (C) Smokeless burning (D) Less erosion on furnace wall

Description : Use of pulverised coal in boilers provides (A) Higher calorific value (B) Better combustion (C) Smokeless burning (D) Less erosion on furnace wall

Last Answer : (B) Better combustion

Explain higher and lower calorific value of a coal having following composition by mass Carbon 81%,Hydrogen 7%, Oxygen 8%,Nitrogen 2.5%, sulphur 1.5% and remaining is ash

Description : Explain higher and lower calorific value of a coal having following composition by mass Carbon 81%,Hydrogen 7%, Oxygen 8%,Nitrogen 2.5%, sulphur 1.5% and remaining is ash

Last Answer : Carbon C = 81% = 0.81 Hydrogen = H2 = 7% = 0.07 Oxygen = O2 = 8% = 0.08 Nitrogen = N = 2.5% = 0.025 Sulphur = S =1.5% = 0.015 Ash = 2.5% = 0.025 Dulong's formula: H.C.V. of coal = 33800 C + 144500 ... = H.C.V.- 9H2 x 2442 KJ / Kg = 36187.5- 9 x 0.07 x 2442 L.C.V. of coal = 34649.04 KJ / Kg 

Low temperature oxidation of coal resulting from bad storage conditions does not decrease its (A) Caking power (B) Calorific value (C) Hydrogen content (D) Oxygen content

Description : Low temperature oxidation of coal resulting from bad storage conditions does not decrease its (A) Caking power (B) Calorific value (C) Hydrogen content (D) Oxygen content

Last Answer : (D) Oxygen content

A coal having higher volatile matter content will necessarily have lower (A) Ash fusion temperature (B) Calorific value (C) Ignition temperature (D) Caking index

Description : A coal having higher volatile matter content will necessarily have lower (A) Ash fusion temperature (B) Calorific value (C) Ignition temperature (D) Caking index

Last Answer : (C) Ignition temperature

A coal gasifier operating at 20 atm. (e.g. Lurgi gasifier) as compared to one operating at atmospheric pressure (e.g. Kopper-Totzek or Winkler gasifier) will produce a gas having (A) Higher methane content and thus higher calorific value (B) Higher carbon monoxide content(C) Lower carbon dioxide content(D) None of these

Description : A coal gasifier operating at 20 atm. (e.g. Lurgi gasifier) as compared to one operating at atmospheric pressure (e.g. Kopper-Totzek or Winkler gasifier) will produce a gas having (A) Higher ... calorific value (B) Higher carbon monoxide content (C) Lower carbon dioxide content (D) None of these

Last Answer : (A) Higher methane content and thus higher calorific value

Natural gas recovered along with crude oil from oil wells is called wet natural gas which has a higher __________ compared to the dry natural gas. (A) Unsaturated hydrocarbon content (B) Calorific value (C) Quantity of propane (D) Quantity of butane

Description : Natural gas recovered along with crude oil from oil wells is called wet natural gas which has a higher __________ compared to the dry natural gas. (A) Unsaturated hydrocarbon content (B) Calorific value (C) Quantity of propane (D) Quantity of butane

Last Answer : (B) Calorific value

Recall homework 2 in which we calculated emissivity for a single layer atmosphere. If the atmosphere were to suddenly become a perfect emitter (i.e., if e = 1 rather than e = 0.8), what would happen to the surface temperature? (a) The surface temperature would be lower. (b) The surface temperature would be the same. (c) The surface temperature would be higher. (d) There would be initial warming followed by cooling as the planet moves toward radiative equilibrium.

Description : Recall homework 2 in which we calculated emissivity for a single layer atmosphere. If the atmosphere were to suddenly become a perfect emitter (i.e., if e = 1 rather than e = 0.8), ... . (d) There would be initial warming followed by cooling as the planet moves toward radiative equilibrium.

Last Answer : (c) The surface temperature would be higher.

Maintain 850 OC for 1 hour (soaking time).  Cool the material to 60 OC in 4 hours. a) Calculate the efficiency of the furnace, if the specific heat of steel is 0.12 kcal/kgOC and fuel oil consumption per batch is 1400 litres.  GCV of fuel oil - 10200 kcal/kg,  Cost of fuel oil - Rs. 46,000/kL,  Sp. gr. of fuel oil - 0.92. b) Due to high cost of oil, the plant management decides to convert to a lower operating cost LPG fired furnace lined on the inside with ceramic fibre insulation and with an operating efficiency of 80%, for same requirement. The investment towards installation of the new furnace is Rs. 50 lakhs. Calculate the Return on Investment, if the plant operates two batches per day and 250 days in a year.  Cost of LPG - Rs. 75/kg,  GCV of LPG - 12500 kcal/kg.

Description : In a heat treatment shop, steel components are heat-treated in batches of 80 Tons. The  heat treatment cycle is as follows;  Increase temperature from 30 OC to 850 OC in 3 hours.  ... efficiency of 80%, for same requirement. The investment towards installation of  the new furnace is Rs. 50

Last Answer : Quantity of steel treated per batch - 80 Tons a. Efficiency of Furnace: Useful heat supplied to steel - 80000 x 0.12 x (850 - 30)   = 7872000 kcal/batch .1 mark Total heat ... = Rs. 64400/batch Efficiency of new LPG furnace - 80% Heat supplied in new LPG furnace - 7872000/0.8

Bomb calorimeter can be used to determine the __________ of the coal. (A) Sulphur content (B) Calorific value (C) Both (A) & (B) (D) Neither (A) nor (B)

Description : Bomb calorimeter can be used to determine the __________ of the coal. (A) Sulphur content (B) Calorific value (C) Both (A) & (B) (D) Neither (A) nor (B)

Last Answer : (C) Both (A) & (B)

Ceramic coating material for furnace refractory, which increases itsemissivity and thus the radiation heat transfer rate in the furnace, comprises of (A) Graphite powder (B) Thoria (C) Zircon powder (D) Beryllium

Description : Ceramic coating material for furnace refractory, which increases itsemissivity and thus the radiation heat transfer rate in the furnace, comprises of (A) Graphite powder (B) Thoria (C) Zircon powder (D) Beryllium

Last Answer : (C) Zircon powder

Temperature of a furnace fired with low calorific value fuel gas (i.e. lean gas) can be increased by (A) Preheating the combustion air (B) Oxygen enrichment of combustion air (C) Preheating the fuel gas (D) All (A), (B) & (C)

Description : Temperature of a furnace fired with low calorific value fuel gas (i.e. lean gas) can be increased by (A) Preheating the combustion air (B) Oxygen enrichment of combustion air (C) Preheating the fuel gas (D) All (A), (B) & (C)

Last Answer : (D) All (A), (B) & (C)

Which of the following advantages is not associated with the use of preheated air for combustion of a fuel in the furnace? (A) Increase in calorific value of the fuel (B) Increase in flame temperature (C) Reduction in scale losses (D) Saving in fuel consumption

Description : Which of the following advantages is not associated with the use of preheated air for combustion of a fuel in the furnace? (A) Increase in calorific value of the fuel (B) Increase in flame temperature (C) Reduction in scale losses (D) Saving in fuel consumption

Last Answer : (A) Increase in calorific value of the fuel

Use of preheated air for combustion of fuel in the furnace, increases the (A) Scale losses of the furnace stock (B) Calorific value of the fuel (C) Flame temperature (D) None of these

Description : Use of preheated air for combustion of fuel in the furnace, increases the (A) Scale losses of the furnace stock (B) Calorific value of the fuel (C) Flame temperature (D) None of these

Last Answer : (C) Flame temperature

Catalytic cracking compared to thermal cracking of residue of vacuum distillation of crude oil (A) Gives higher yield of petrol (B) Lower octane number of petrol (C) Higher sulphur content in the product (D) Higher gum forming material in petro

Description : Catalytic cracking compared to thermal cracking of residue of vacuum distillation of crude oil (A) Gives higher yield of petrol (B) Lower octane number of petrol (C) Higher sulphur content in the product (D) Higher gum forming material in petro

Last Answer : (A) Gives higher yield of petrol

Presence of __________ in a dry gaseous fuel does not contribute to its calorific value. (A) Sulphur (B) Oxygen (C) Hydrogen (D) Carbon

Description : Presence of __________ in a dry gaseous fuel does not contribute to its calorific value. (A) Sulphur (B) Oxygen (C) Hydrogen (D) Carbon

Last Answer : (B) Oxygen

Which of the following constituents of a fuel does not contribute to its calorific value on combustion? (A) Hydrogen (B) Sulphur (C) Carbon (D) None of these

Description : Which of the following constituents of a fuel does not contribute to its calorific value on combustion? (A) Hydrogen (B) Sulphur (C) Carbon (D) None of these

Last Answer : (D) None of these

Ratio of primary air to secondary air increases with increase in the rank of coal, because the (A) High rank coals have higher amount of volatile matter (B) Ratio of fixed carbon to volatile matter increases (C) Oxygen content progressively decreases (D) Calorific value of the coal increases

Description : Ratio of primary air to secondary air increases with increase in the rank of coal, because the (A) High rank coals have higher amount of volatile matter (B) Ratio of fixed carbon to volatile matter increases (C) Oxygen content progressively decreases (D) Calorific value of the coal increases

Last Answer : (B) Ratio of fixed carbon to volatile matter increases

TIG welding, thoriated tungsten electrodes are used, because it (A) Has higher current carrying capacity (B) Has better electron emissivity (C) Is stronger than ordinary tungsten (D) Is easy to prepare

Description : TIG welding, thoriated tungsten electrodes are used, because it (A) Has higher current carrying capacity (B) Has better electron emissivity (C) Is stronger than ordinary tungsten (D) Is easy to prepare

Last Answer : Option B

Washing of coal (A) Reduces its sulphur and ash content (B) Controls its ash fusibility and increases its calorific value(C) Improves its coking properties(D) All (A), (B) and (C)

Description : Washing of coal (A) Reduces its sulphur and ash content (B) Controls its ash fusibility and increases its calorific value (C) Improves its coking properties (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

A fuel with high heat release rate will (A) Require smaller combustion chamber (B) Have high calorific value (C) Have high adiabatic flame temperature (D) None of these

Description : A fuel with high heat release rate will (A) Require smaller combustion chamber (B) Have high calorific value (C) Have high adiabatic flame temperature (D) None of these

Last Answer : (A) Require smaller combustion chamber

Calorific value of furnace oil is about __________ Kcal/kg. (A) 10,000 (B) 15,000 (C) 5,000 (D) 20,000

Description : Calorific value of furnace oil is about __________ Kcal/kg. (A) 10,000 (B) 15,000 (C) 5,000 (D) 20,000

Last Answer : (A) 10,000

Which of the following fuels has the highest calorific value per unit mass (kcal/kg)? (A) Coal (B) Kerosene (C) Natural gas (D) Furnace oil

Description : Which of the following fuels has the highest calorific value per unit mass (kcal/kg)? (A) Coal (B) Kerosene (C) Natural gas (D) Furnace oil

Last Answer : (D) Furnace oil

Which of the following has the highest gross calorific value? (A) Blast furnace gas (B) Coke oven gas (C) Carburetted water gas (D) Oil refinery gas

Description : Which of the following has the highest gross calorific value? (A) Blast furnace gas (B) Coke oven gas (C) Carburetted water gas (D) Oil refinery gas

Last Answer : (D) Oil refinery gas

Higher concentration of CO2 in atmosphere (A) Allows visible solar radiation (ultraviolet) of short wave-length to pass through (B) Reflects and absorbs the longer wavelength (infra-red) radiations (C) Prevents solar heat being radiated out completely, resulting in 'heat trap' i.e., global warming (D) All (A), (B) and (C)

Description : Higher concentration of CO2 in atmosphere (A) Allows visible solar radiation (ultraviolet) of short wave-length to pass through (B) Reflects and absorbs the longer wavelength (infra-red) radiations (C) Prevents solar heat being ... in 'heat trap' i.e., global warming (D) All (A), (B) and (C)

Last Answer : (D) All (A), (B) and (C)

Heat transfer to the water wall in a high pressure water wall type boiler furnace is mainly by (A) Conduction (B) Convection (C) Radiation (D) Both 'a' & 'b'

Description : Heat transfer to the water wall in a high pressure water wall type boiler furnace is mainly by (A) Conduction (B) Convection (C) Radiation (D) Both 'a' & 'b'

Last Answer : Option C