heat engine questions and answers pdf

Heat Engine Questions And Answers Pdf

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Ans: c.

Which of the following variables controls the physical properties of a perfect gas a pressure Why it is important to formulate the law for open systems can be illustrated with Fig. It only transforms from one form to another.

300+ TOP I.C. ENGINES MCQs and Answers – Mechanical Engineering

Ans: c. In a diesel engine, the fuel is ignited by a spark b injected fuel c heat resulting from compressing air that is supplied for combustion d ignition e combustion chamber. Ans: d. Supercharging is the process of a supplying the intake of an engine with air at a density greater than the density of the surrounding atmosphere b providing forced cooling air c injecting excess fuel for raising more load d supplying compressed air to remove combustion products fully e raising exhaust pressure.

Ans: a. Does the supply of scavenging air at a density greater than that of atmosphere mean engine is supercharged? Ans: b. The ratio of indicated thermal efficiency to the corresponding air standard cycle efficiency is called a net efficiency b efficiency ratio c relative efficiency d overall efficiency e cycle efficiency. Compression ratio of LC. The air standard efficiency of an Otto cycle compared to diesel cycle for the given compression ratio is a same b less c more d more or less depending on power rating e unpredictable.

If the intake air temperature of I. All heat engines utilize a low heat value of oil b high heat value of oil c net claorific value of oil d calorific value of fuel e all of the above. An engine indicator is used to determine the following a speed b temperature c volume of cylinder d m. Fuel oil consumption guarantees for I. In case of gas turbines, the gaseous fuel consumption guarantees are based on a high heat value b low heat value c net calorific value d middle heat value e calorific value.

The maximum temperature in the I. The thermal efficiecny of a diesel cycle having fixed compression ratio, with increase in cut-off ratio will a increase b decrease c be independent d may increase or decrease depending on other factors e none of the above. Pick up the wrong statement a 2-stroke engine can run in any direction b In 4-stroke engine, a power stroke is obtained in 4-strokes c thermal efficiency of 4-stroke engine is more due to positive scavenging d petrol engines work on otto cycle e petrol engines occupy more space than diesel engines for same power output.

Ans: e. Combustion in compression ignition engines is a homogeneous b heterogeneous c both a and b d laminar e turbulent. The specific fuel consumption per BHP hour for diesel engine is approximately a 0. Crankcase explosion in I. Compression loss in I. C engines occurs duto a leaking piston rings b use of thick head gasket c clogged air-inlet slots d increase in clearance volume caused b bearing-bushing wear e all of the above.

The specific fuel consumption per BH hour for a petrol engine is approximately a 0. The air requirement of a petrol engine during starting compared to theoretical airequired for complete combustion is a more b loss c same d may be more or less depending on engine capacity e unpredictable. The inlet value of a four stroke cycle I.

Which of the following is not an interns combustion engine a 2-stroke petrol engine b 4-stroke petrol engine c diesel engine d gas turbine e steam turbine. If one cylinder of a diesel engine receives more fuel than the others, then for that cylinder the a exhaust will be smoky b piston rings would stick into piston grooves c exhaust temperature will be high d engine starts overheating e scavenging occurs. The output of a diesel engine can be increased without increasing the engine revolution or size in following way a feeding more fuel b increasing flywheel size c heating incoming air d scavenging e supercharging.

It the temperature of intake air in IC engines is lowered, then its efficiency will a increase b decrease c remain same d increase upto certain limit and then decrease e decrease upto certain limit and then in-crease.

The precess of breaking up or a lipuid into fine droplets by spraying is called a vaporisation b carburetion c ionisation d injection e atomisation. As a result of detonation in an I. Which of the following statements is correct?

Most high speed compression engines operate on a Diesel cycle b Otto cycle c Dual combustion cycle d Special type of air cycle e Carnot cycle. The accunmulation of carbon in a cylinder results in increase of a clearance volume b volumetric efficiency c ignition time d effective compression ratio e valve travel time.

Which of the following medium is compressed in a Diesel engine cylinder a air aione b air and fuel c air and lub oil d fuel alone e air, fuel and lub oil. The air-fuel ratio of the petrol engine is controlled by a fuel pump b governor c injector d carburettor e scavenging. Diesel fuel, compared to petrol is a less difficult to ignite b just about the same difficult to ignite c more difficult to ignite d highly ignitable e none of the above.

When crude oil is heated, then which of the following hydrocarbon is given off first. The rating of a diesel engine, with increase in airintlet temperature, will a increase linearly b decrease linearly c increase parabolically d decrease parabolically e first decrease linearly and then increase parabolically.

A 75 cc engine has following parameter as 75 cc a fuel tank capacity b lub oil capacity c swept volume d cylinder volume e clearance volume. A heat engine utilises the a calorific value of oil b low heat value of c high heat value of oil d mean heat value of oil e all of the above. Gaseous-fuel guarantees are based on a calorific value of oil b low heat value of oil c high heat value of oil d mean heat value of oil e all of the above.

Fuel consumption of diesef engines is not guaranteed at one quarter load because at such low loads a the friction is high b the friction is unpredictable c the small difference in cooling water temperature or in internal friction has a disproportionate effect d the engine is rarely operated e none of the above.

Polymerisation is a chemical process in which molecules of a compound become a larger b slowed down c smaller d liquid e gaseous. The term scavenging is generally associated with a 2-stroke cycle engines b 4-stroke cycle engines c aeroplane engines d diesel engines e high efficiency engines.

The cam shaft of a four stroke I. Most high speed compression engines operate on a Otto cycle b Diesel cycle c Dual cycle d Carnot cycle e Two stroke cycle. The specific fuel consumption of a petrol engine compared to diesel engine of same H.

A diesel engine as compared to petrol engine both running ar rated load is a more efficient b less efficient c equally efficient d unperdictable e other factors will decide it. The size of inlet valve of. In a cycle, the spark lasts roughly for a 1 sec b 0. Which of the following is false statement : Excess quantities of sulphur in diesel fuel are Objectionable because it may cause the following a piston ring and cylinder wear b formation of hard coating on piston skirts c oil sludge in the engine crank case d detonation e forms corrosive acids.

Which of the following is false statement. Some of the methods used to reduce diesel smoke are as follows a using additives in the fuel b engine derating i. The fuel air ratio in a petrol engine fitted with suction carburettor, operating with dirty air filter as compared to clean filter will be a higher b lower c remain unaffected d unpredictable e none of the above.

Pick up the wrong statement about supercharging a supercharging reduces knocking in diesel engines b there can be limited supercharging in petrol engines because of detonation c supercharging at high altitudes is essential d supercharging results in fuel economy e supercharging is essential in aircraft engines. The actual volume of fresh charge admitted in 4-stroke petrol engine is a equal to stroke volume b equal to stroke volume and clearance volume c less than stroke volume d more than stroke volume e more than cylinder volume.

The magneto in an automobile is basically c transformer b d. The reason for supercharging in any engine is to a increase efficiency b increase power c reduce weight and bulk for a given out-put d effect fuel economy e none of the above. The operation of forcing additional air under pressure in the engine cylinder is known as a scavenging b turbulence c supercharging d pre-ignition e dissociation and carburretion of fuel.

Supercharging is essential in a diesel engines b gas turbines c petrol engines d aircraft engines e marine engines. The minimum cranking speed in case of petrol engine is about a half the operating speed b one-fourth of operating speed c rpm d rpm e rpm Ans: d. The mean effective pressure obtained from engine indicator indicates the a maximum pressure developed b minimum pressure c instantaneous pressure at any instant d exhaust pressure e average pressure.

For the same power developed in I. Scavenging is usually done to increase a thermal efficiency b speed c power output d fuel consumption e all of the above.

Which of the following is the lightest and most volatile liquid fuel a diesel b kerosene c fuel oil d gasoline e lub oil. The theoretically correct air fuel ratio for petrol engine is of the order of a 6 : 1 b 9 : 1 c 12 : 1 d 15 : 1 e 20 : 1. Air fuel ratio for idling speed of a petrol engine is approximately a 1 : 1 b 5 : 1 c d 15 : 1 e 20 : 1.

Air fuel ratio at which a petrol engine can not work is a 8 : 1 b 10 : 1 c 15 : 1 d 20 : 1 and less e will work at all ratios. For maximum power generation, the air fuel ratio for a petrol engine for vehicles, is of the order of a 9 : 1 b 12 : 1 c 15 : 1 d 18 : 1 e 1. The following volume of air is required for consuming 1 liter of fuel by a four stroke engine a 1 m3 b 5 m3 c m3 d m3 e m3.

A 5 BHP engine running at full load would consume diesel of the order of a 0. Diesel engine can work on very lean air fuel ratio of the order of 30 : 1. A petrol engine can also work on such a lean ratio provided a it is properly designed b best quality fuel is used c can not work as it is impossible d flywheel size is proper e engine cooling is stopped.

A diesel engine has a 1 valve b 2 valves b 3 valves d 4 valves e no valve. The knock in diesel engine occurs due to a instantaneous and rapid burning of the first part of the charge b instantaneous atuo iginition of last part of charge c delayed burning of the first part of the charge d reduction of delay period e all ot the above. A stoichiometric air-fuel ratio is a chemically correct mixture b lean mixture c rich mixture for idling d rich mixture for over loads e the ratio used at full rated parameters.

In a naturally aspirated diesel engine, the air is supplied by a a supercharger b a centrifugal blower c a vacuum chamber d an injection tube e forced chamber Ans: c.

In loop scavenging, the top of the piston is a flat b contoured c slanted d depressed e convex shaped. In the crankcase method of scavenging, the air pressure is produced by a supercharger b centrifugal pump c natural aspirator d movement of engine piston e reciprocating pump. Ignition quailty of petrol is expressed by a octane number b cetane number c calorific value d self ignition temperature e distillation temperature.

Iso-oct ,ne a has octane number of 0 b has octane number of 50 c has octane number of d is an index of detonation quality e is an index of knocking quality. Octane number is determined by comparing the performance of the petrol with the following hydrocarbons a iso-octane b mixture of normal heptane and iso-oc-tane c alpha methyl napthalene d mixture of methane and ethane e mixture of paraffins and aromatics. Cetane a has zero cetane number b has cetane number c helps detonation d is a straight chain paraffin e determines the efficiency of an I.

Ethyl fluid is used a to increase the octane rating of the fuel b to increase the cetane rating of the fuel c as a defrosting agent d as a superior type of fluid compared to others e to improve lubricating quality of fuel. The self-ignition temperature of diesel oil compared to petrol is a higher b lower c same d depends on quality of fuel e unpredictable?

Normal heptane a accelerates auto-ignition b helps to resist auto-ignition c does not affect auto-ignition d has no relation with auto-ighition e retards auto-ignition. Cetane number is determined by comparing the performance of diesel oil with the following hydrocarbons a cetane b mixture of cetane and alphamethyl napthalene c ethylene dibromide d mixture of aldehydes and ketones e mixture of cetane with tetra-ethyl lead.

Which is correct statement about reaction time for autoignition of fuel and the fuel air ratio a lean mixture has high reaction time b rich mixture has high reaction time c chemically correct mixture has mini-mum reaction time d all of the above. Violent sound pulsations within the cylinder of an I.

Ignition lag is a the time taken by fuel after injection before top dead center to reach upto auto-ignition temperature b time before actual fuel injection and the pump plunger starts to pump fuel c time corresponding to actual injection and top dead center d time corresopnding to actual ingition and top dead center e none of the above. The spark plug gap is normally maintained at a 0. The function of a fuel pump in a petrol pump is to a inject fuel in cylinder b supply fuel when carburettor fails c pump fuel so that it reaches carburettor to improve thermal efficiency d does not exist.

The delay period in petrol engine is of the order of a 0. Detonation is caused by the following unstable compounds a peroxides, aldehydes and ketones b peroxides, aldehydes, oxides and sul-phides c aldehydes, oxides and ketones d ketones and sulphur compounds e none of the above.

Which is false statement about advantages of V-type engine a compact design requiring lesser space b improved distribution of air to cylinder c casting less liable to distortion d reduced torsional vibration because of shorter crankshaft e less overhead clearance.

The pistons are usually given a coating such as tin plating in order to a reduce weight b conduct heat efficiently c reduce possibility of scoring d reduce friction e increase lubrication effect.

Simple heat engine question paper

During a cyclic process, a heat engine absorbs J of heat from a hot reservoir, does work and ejects an amount of heat J into the surroundings cold reservoir. Calculate the efficiency of the heat engine? The efficiency of heat engine is given by. This steam is used to do work and heat is ejected to the surrounding air at temperature K. Calculate the maximum efficiency it can have? The steam engine is not a Carnot engine, because all the process involved in the steam engine are not perfectly reversible.

Experiment: Heat Engines Objectives: To construct a simple heat engine To explore the phases of the heat engine To calculate the work performed by the heat engine To calculate the efficiency of the heat engine Equipment: Low friction glass syringe 25 mL Erlenmeyer flask small black rubber cork stopcock valve 3 mL beakers or comparable size a ring stand with test tube clamp. Introduction: Machines are devices that convert energy into work or in some cases, one form of work into another. Heat engines are machines that convert heat energy into mechanical work. In order for a heat engine to perform it must have a working substance, such as a gas or liquid that must absorb heat energy, perform work and discard the remaining energy that cannot be transformed into work. In this experiment, you will construct a heat engine that will utilize air as its working substance. Heat energy will be absorbed from a hot water source and work will be performed via a frictionless glass syringe. A cold water source will serve to absorb the unusable heat energy from the heat engine.


Get help with your Heat engine homework. Access the answers to hundreds of Heat engine questions that are explained in a way that's easy for you to.


Simple heat engine question paper

Problem sets First Law of Thermodynamics One of the trusted Educational Blog.

Don't show me this again. Thermodynamics is exceedingly general in its applicability, and this makes it a powerful tool for solving many kinds of important problem. Find the rate of entropy generation in the turbine. PV diagrams - part 1: Work and isobaric processes. Carnot cycle a.

A 10 done clear. B 1 done clear. C 9 done clear.

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Сьюзан приходилось слышать, что сильный страх парализует тело, - теперь она в этом убедилась. Ее мозг мгновенно осознал происходящее, и она, вновь обретя способность двигаться, попятилась назад в темноте с одной только мыслью - бежать. И сразу же услышала треск. Хейл, сидя на плите и действуя вытянутыми ногами как тараном, сорвал решетчатую дверь с петель, ворвался в комнату и теперь приближался к ней большими прыжками. Сьюзан швырнула ему под ноги настольную лампу, но Хейл легко преодолел это препятствие. Он был уже совсем .

300+ TOP I.C. ENGINES MCQs and Answers – Mechanical Engineering

ГЛАВА 3 Вольво Сьюзан замер в тени высоченного четырехметрового забора с протянутой поверху колючей проволокой.

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