Description : External combustion/steam engine cannot be started immediately.
Last Answer : Heating water to produce steam takes time, so the engine cannot be started instantly. To keep the steam ready fuel must be burnt continuously even if the engine is at rest.
Description : What are the disadvantages / drawbacks of an external combustion / steam engine?
Last Answer : a) Steam engine is bulky and heavy. It cannot be used in small machines. b) The efficiency is very low. c) The engine cannot be started immediately.
Description : Which of the following is not an internal combustion engine? a. petrol engine b. steam turbine c. diesel engine d. gas turbine
Last Answer : ANSWER b. steam turbine
Description : Name one or more sources of noise bearing on electronic communications. A. Steam boiler B. Galaxies C. Internal combustion engine D. Both B and C
Last Answer : D. Both B and C
Description : The most efficient heat engine that can operate between two temperature reservoirs T1 and T2 is: w) jet engine x) internal combustion engine y) Carnot engine (pron: car-no) z) steam engine
Last Answer : ANSWER: Y -- CARNOT ENGINE
Description : If the temperature of intake air in internal combustion engine is lowered, the efficiency will a. increase b. decrease c. remains same d. increases upto certain limit and then decrease
Last Answer : ANSWER a. increase
Description : Thermal efficiency of an internal combustion engine on weak mixture is a. higher b. lower c. unaffected d. unpredictable
Last Answer : ANSWER a. higher
Description : The efficiency of a internal combustion engine normally is of the order of a. 15-20 % b. 20-25% c. 25-30% d. 30-35%
Last Answer : ANSWER d. 30-35%
Description : If the intake air temperature of Internal combustion engine increases, its efficiency will a. increase b. decrease c.remains same d unpredictable
Last Answer : ANSWER b. decrease
Description : . Thermal efficiency of an internal combustion engine is around __________ percent. (A) 8 (B) 35 (C) 65 (D) 80
Last Answer : Option B
Description : Thermal efficiency of an internal combustion engine is around __________ percent. (A) 8 (B) 35 (C) 65
Description : What is an external combustion engine? Give example.
Last Answer : A heat engine in which combustion of fuel takes place outside the cylinder of the engine is called external combustion engine. Ex: Steam engine.
Description : Which of the following best describes both Stirling and Ericson engines? a. Internal combustion engine b. External combustion engine c. Diesel cycle d. Rankine cycle
Last Answer : External combustion engine
Description : Heat engine deriving its power from the energy liberated by the explosion of a mixture of some hydrocarbon, in a gaseous or vaporized form. a. Dual Combustion Engine b. Internal Combustion Engine c. External Combustion Engine d. None of the above
Last Answer : Internal Combustion Engine
Description : Ratio of actual indicated work to hypothetical indicated work in a steam engine is the (a) Indicated thermal efficiency (b) Friction factor (c) Mechanical efficiency (d) Diagram factor
Last Answer : Ans : d
Description : Which of the following has the least thermal efficiency? (A) Steam engine (B) Carnot engine (C) Diesel engine (D) Otto engine
Last Answer : A) Steam engine
Description : A simple steam engine receives steam from the boiler at 180˚C and exhausts directly into the air at 100˚C. What is the upper limit of its efficiency? a. 11.28 % b. 36.77 % c. 20.36 % d. 17.66 %
Last Answer : 17.66 %
Description : The efficiency of Carnot cycle is maximum for (a) gas engine (b) well lubricated engine (c) petrol engine (d) steam engine (e) reversible engine.
Last Answer : Answer : e
Description : Which of the following is not applicable to fluidised bed combustion of coal? (A) It cannot burn low grade coal (B) It achieves higher fuel combustion efficiency (C) Less heat transfer surface area is required in boilers (D) None of these
Last Answer : (A) It cannot burn low grade coal
Description : Why the Thermal efficiency of the steam power plant is quite low?
Last Answer : In Steam power station, more than 50% of the total heat of combustion is lost as heat rejected to the condenser and the loss is unavoidable as the heat energy cannot be converted in to mechanical ... lowest temperature. This is the reason that the thermal efficiency of the power plant is quite low.
Description : In a Rankine cycle, regeneration results in higher efficiency because (a) Pressure inside the boiler increases [GATE-2003] (b) Heat is added before steam enters the low pressure turbine (c) ... temperature of heat addition in the boiler increases (d) Total work delivered by the turbine increases
Last Answer : (c) Average temperature of heat addition in the boiler increases
Description : The efficiency of superheat Rankine cycle is higher than that of simple Rankine cycle because [GATE-2002] (a) The enthalpy of main steam is higher for superheat cycle (b) The mean temperature of heat ... temperature of steam in the condenser is high (d) The quality of stem in the condenser is low
Last Answer : (b) The mean temperature of heat addition is higher for superheat cycle
Description : The temperature of boiling water in a steam engine may be high because - (1) there are dissolved substances in water (2) there is low pressure inside the boiler (3) there is high pressure inside the boiler (4) the lire is at very high temperature
Last Answer : (3) there is high pressure inside the boiler Explanation: In the boiler of a steam engine, there is a firebox where coal is shoveled into. The coal is kept burning at a very high temperature, and ... reservoir; the steam is then controlled by a slide valve to move into a cylinder to push the piston.
Description : The temperature of boiling water in a steam engine may be high because : (1) there are dissolved substances in water (2) there is low pressure inside the boiler (3) there is high pressure inside the boiler (4) the fire is at very high temperature
Last Answer : there is high pressure inside the boiler
Description : If petrol is used in a diesel engine a. higher knocking will occur b. efficiency will be low c. low power will be obtained d. black smoke will be produced
Last Answer : ANSWER a. higher knocking will occur
Description : Which of the following represents the perpetual motion of the first kind (a) engine with 100% thermal efficiency (b) a fully reversible engine (c) transfer of heat energy from low ... its own energy (e) production of energy by temperature differential in sea water at different levels.
Last Answer : Answer : d
Description : iesel engine has less reserve torque then spark ignition because ∙ Torque-speed curve is governed by volumetric efficiency of fuel pump and engine cylinder ∙ Torque is a function of thermal efficiency ∙ Diesel engine has generally low speed engine ∙ None of the above
Last Answer : ∙ Torque is a function of thermal efficiency
Description : To reduce the stack loss, heat recovery from flue gas can be done by (A) Preheating of cold stock (B) Preheating of combustion air (C) Steam generation in waste heat boilers (D) All (A), (B) and (C)
Last Answer : (D) All (A), (B) and (C)
Description : In case of pulverised coal fired steam boiler, the secondary air serves the main purpose of (A) Transportation of coal (B) Drying of coal (C) Combustion of coal by supplying it around the burner (D) Preheating the primary air
Last Answer : (C) Combustion of coal by supplying it around the burner
Description : Steam is intermittently admitted into the fuel bed during the production of producer gas to (A) Convert CO to CO2 (B) Increase the combustion rate (C) Increase the gas production rate (D) Minimise the chances of clinker formation
Last Answer : (D) Minimise the chances of clinker formation
Description : Which of the following is not endothermic in nature? (A) Combustion of sulphur (B) Gasification of carbon (C) Thermal cracking of fuel oil (D) Steam reforming of naphtha
Last Answer : (A) Combustion of sulphur
Description : A boiler is an enclosed vessel that provides a means for ________ and ______ heat to water until it becomes hot water or steam. a. Generate, boiler b. Condenser, loop c. Combustion, transfers d. All of above
Last Answer : c. Combustion, transfers
Description : A __________ is a type of heat exchange system where water is heated to its' boiling point via combustion of a fuel blown through a tube submerged in water. a. Condensate loop b. Hyperbolic cooling tower c. Steam boiler d. All of above
Last Answer : c. Steam boiler
Description : Producer gas is obtained by A. partial combustion of coal, coke, anthracite coal or charcoal in a mixed air steam blast B. carbonisation of bituminous coal C. passing steam over incandescent coke D. passing air and a large amount of steam over waste coal at about 650°C
Last Answer : Answer: A
Description : In a boiler enthalpy of water supplied was 2000 kJ/kg. Enthalpy being added by fuel combustion is 3200 kJ/kg. Using first law of thermodynamics, find amount of heat supplied if steam generation rate is 10 tons per hour.
Last Answer : Heat supplied Q = m (h2-h1) …….(Steady flow energy equation for boiler) ; h2=3200 KJ/kg h1=2000 KJ/kg m = 10 Tons /hour = (10 x 1000)/3600 kg/sec = 2.77 Kg/sec Q = 2.77(3200-2000) = 3324 KJ/sec heat supplied for 10 Tons/hr steam generation
Description : The main feature of Carnot refrigeration cycle is that, it (A) Does not need the addition of external work for its functioning (B) Transfers heat from high temperature to low temperature (C) Accomplishes the reverse effect of the heat engine (D) None of these
Last Answer : (C) Accomplishes the reverse effect of the heat engine
Description : Orsat apparatus is meant for (A) Gravimetric analysis of flue gas (B) Finding out combustion efficiency (C) Direct determination of nitrogen in flue gas by absorbing it in ammoniacal cuprous chloride (D) None of these
Last Answer : (D) None of these
Description : Higher efficiency in the combustion of solid fuel cannot be achieved by (A) Proper fuel preparation (B) Keeping the flue gas exhaust temperature very high (C) Adopting efficient-fuel firing technique & equipment (D) Supplying correct quantity of combustion air
Last Answer : (B) Keeping the flue gas exhaust temperature very high
Description : Efficiency of the combustion of a fuel is judged by the __________ the flue gas. (A) % of CO2 in (B) % of O2 in (C) Temperature of (D) Colour of
Last Answer : (B) % of O2 in
Description : Higher fuel combustion efficiency cannot be achieved by (A) Preheating of fuel gases & combustion air (B) Reducing sulphur content in the fuel (C) Adopting proper fuel firing technique & fuel preparation (D) Supplying correct amount of combustion air
Last Answer : (B) Reducing sulphur content in the fuel
Description : High sulphur content in a fuel __________ of the flue gases. (A) Decreases the dew point (B) Increases the dew point (C) Reduces the combustion efficiency by limiting the permissible temperature reduction (D) Both (B) and (C)
Last Answer : (D) Both (B) and (C)
Description : Combustion of pulverised coal compared to the lumpy coal (A) Provides better control of furnace temperature (B) Facilitates combustion with lower excess air (C) Provides higher thermal efficiency & flame temperature (D) All (A), (B) & (C)
Last Answer : (D) All (A), (B) & (C)
Description : are portable devices capable of estimating the combusting efficiency of furnaces, boilers, or other fossil fuel burning machines. a) Sound analyzer. c) Combustion analyzer. b) Light analyzer. d)Temperature analyzer
Last Answer : Combustion analyzer.
Description : measures oxygen and temperature of the flue gas. a) Fuel efficiency monitor. b) Combustion analyzer. c) Contact thermometer. d) Infrared thermometer.
Last Answer : Combustion analyzer
Description : are portable devices capable of estimating the combusting efficiency of furnaces, boilers, or other fossil fuel burning machines. a) Sound analyzer. b) Light analyzer. c) Combustion analyzer. d) Temperature analyzer.
Description : What is defined as the ratio of the net electrical power output to the rate of fuel energy input? A. Combustion efficiency B. Thermal efficiency C. Overall efficiency D. Furnace efficiency
Last Answer : Overall efficiency
Description : What is the ratio of the useful heat extracted to heating value? A. Combustion efficiency B. Phase efficiency C. Heat efficiency D. Work efficiency
Last Answer : Combustion efficiency
Description : The efficiency of a dual combustion cycle __________ upon cut-off ratio. A. depends B. does not depend