Here are two turbines. A Bell-Coleman air refrigeration cycle works as a reversed: Assertion (A): The thermal efficiency of Brayton cycle with regeneration decreases as the compressor ratio increases. Today, there exist two large markets for industrial gas turbines. A gas turbine cycle with heat exchanger and reheating improves, Both thermal efficiency and specific power output, Neither thermal efficiency nor specific power output ​. Even low grade fuels can be burnt in gas turbines.Of these statements. (9), the isentropic temperature change, Eq. The calorific value of the fuel used is 43.1 MJ/kg. Assertion (A): The thermal efficiency of gas turbine plants is higher compared todiesel plants. The ratio of specific weighf/h.p. Reason (R): The mechanical efficiency of gas turbines is higher compared to dieselengines. The overall pressure drop in a turbine is the product of pressure dropper stage and number of stages. 2.11. a. Two constant pressure process and two isentropic process, C. Two isobaric process and two isentropic process. Compressors, Gas Turbines And Jet Engines MCQ question is the important chapter for a Mechanical Engineering and GATE students. Consider the following statements pertaining to gas turbines: 1. There is flexibility in the design of different components of gas turbines as different processes take place in different components. The maximum temperature at the inlet to the turbine is 800°C. Assume air as a perfect gas with specific heat ratio γ = 1.4 . The real work done by gas turbine in adiabatic process is then: W T,real = c p (T 3 – T 4s) . Complete expansion of working substance is possible in I.C. Efficiency of the feedwater pump: According to manufacturers informations, the overall efficiency of the feedwater pump can be 75-85% according to the size. 18. Though A and R are true, but R is not correct reason for A. C. Heat drop in the moving blades to the total heat drop in the fixed blades. (a) two isentropic processes and two constant volume processes (b) two isentropic processes and two constant pressure processes (e) two isothermal processes and three constant pressure processes (d) none of the above. This test is Rated positive by 87% students preparing for Mechanical Engineering.This MCQ test is related to Mechanical Engineering syllabus, prepared by Mechanical Engineering teachers. This contains 20 Multiple Choice Questions for Mechanical Engineering Gas Turbine - MCQ Test 1 (mcq) to study with solutions a complete question bank. The work done by gas turbine in isentropic process is then: W T,s = c p (T 3 – T 4s) = 5200 x (1190 – 839) = 1.825 MJ/kg. Mechanical Engineering the Brayton cycle and the Rankine cycle), can achieve a thermal efficiency of around 55%. Mcq Added by: Muhammad Bilal Khattak. σ s = u 2 c 0 = [ 2 ( 1 + ϕ 2 cot ⁡ β 2 ) ] − 1 2. C 61 : 1 . The degree of reaction is defined as the ratio..... A. The general form for the definition of efficiency of a turbocharging process is always based on the comparison of two ideal processes: • The isentropic compression of the working medium (air or mixture) from an initial state 1 to a final state 2 • The isentropic expansion of the exhaust gas from an initial state 3 to a final state 4. 5 shows the effect of the isentropic efficiencies of turbine 1 and turbine 2 on the overall system energy and exergy efficiency. C.3 LP Compressor Isentropic Efficiency 138 C.4 HP Compressor Isentropic Efficiency 139 C.5 HP Turbine Isentropic Efficiency 140 C.6 LP Turbine Isentropic Efficiency 140 C.l Power Turbine Isentropic Efficiency 141 C.8 LP Compressor Capacity 141 C.9 HP Compressor Capacity 143 … Gas turbine cycle (Brayton cycle) is not as efficient as Rankine cycle forsteam. For a Brayton cycle, match the following using codes given below: Use of maximum pressure ratio, corresponding to maximum to minimum cycle temperature ratio in case of Joule cycle gives which one of the following? The pressure ratio in gas turbines is of the order of . The air mass flow rate is 22 kg/s, intake air is at 10°C and 100 kPa, and turbine inlet temperature is 1250°C. please do not enter any spam link in the comment box Today we study of  multiple  choice questions (mcq) on f... Mcq on Gas Turbine (objectives questions and answers). ConversionConversion Read More Section(Compressors, Gas Turbines and Jet Engines) Each Section contains maximum 70 questions. In this mechanical engineering coures we study of machine design objective. EduRev is a knowledge-sharing community that depends on everyone being able to pitch in when they know something. The given figure shows four plots A, B, C and D of thermal efficiency against pressure ratio: The curve which represents that of a gas turbine plant using Brayton cycle (without regeneration) is the one labelled. In addition, the exergy efficiency of the overall system increases from 24.2% to 39.9% as the isentropic efficiencies of the turbines … relationships for the turbine work, Eq. The speed of rotation of the moving elements of gas turbines is muchhigher than those of steam turbines, 2. The power coefficient (cp)variation of a wind mill with the speed ratio is correctly shown by. Jet propulsion and Rocket propulsion. engines and not in gas turbines. Compressors, Gas Dynamics and Gas Turbines Online Test – Multiple Choice Questions and Answers 1. Turbine performance •The flow in a turbine is also assumed to be adiabatic, though in actual engines there could be turbine blade cooling. Efficiency of the Brayton cycle is higher than the efficiency of the Otto cycle, for the same compression ratio b. In a gas turbine plant air enters the compressor at 1 bar and 7°C. The heat losses are 15% of the calorific value. In this mechanical engineering lecture today we learned about power  plant subjects. Ch 8, Lesson C, Page 3 - Isentropic Efficiency of a Turbine. Gas turbines require 'cooling water for its operations, 4. GAS TURBINES Unit 3: Gas Turbines and Jet Propulsion: Classification of Gas Turbines, Analysis of open cycle gas turbine cycle. Reason (R): In a gas turbine plant, the maximum pressure and temperature arelow when compared to those of reciprocating IC engines. In the paper a calculation methodology of isentropic efficiency of a compressor and turbine in a gas turbine installation on the basis of polytropic efficiency characteristics is presented. EmoticonEmoticon, A. Now, the pressure ratio of the turbine is increased to 5, while maintaining the same inlet conditions. The efficiency factor is included to account for the actual performance of the compressor as opposed to the ideal, isentropic performance. It is compressed to 4 bar with an isentropic eﬃciency of 82%. A 2 : 1 . So additional work is needed to overcome the inefficiency of the compressor to produce a desired CPR. Which of the following is a types of gas turbine power plant ? In this mechanical engineering coures today  we solve of thermodynamics objective. Blade to gas speed ratio. 124. {\displaystyle \,\sigma _ {s}= {\frac {u_ {2}} {c_ {0}}}= [2 (1+\phi _ {2}\cot {\beta _ {2}})]^ {- {\frac {1} {2}}}} for. The one on the right is a real, irreversible turbine and we would like to calculate its isentropic efficiency so we could compare its performance to the performance of another real turbine. Solution for A gas turbine power plant working on Brayton cycle as per the following specifications. A large single-cycle gas turbine typically produces for example 300 megawatts of electric power and has 35–40% thermal efficiency. Similarly, it can be shown that, for a turbine, the isentropic efficiency will increase with pressure ratio and this is due to the reheating of the gas entering the next turbine stage due to … Mcq on Gas turbine power plant (objectives questions and answers). The same turbine can be used for  both plants. 3. 1. D. Two isothermal process and two constant volume process. The degree of reaction of a reaction turbine is the ratio of energytransfer in fixed blade to the overall energy transfer across a stage. Conservatively, we took a value of 87% in our analyses. (11). ... A. compressor efficiency B. isentropic efficiency C. Euler’s efficiency D. pressure coefficient E. pressure ratio. A regenerative Gas turbine operate at steady state, the inlet to the compressor is at 100 KPA and 320 K. the pressure ratio is 9. the inlet to the turbine is 1100 K. the isentropic efficiency of the compressor and turbine is 75%. The blade-to-gas speed ratio can be expressed in terms of the isentropic stage terminal velocity c 0 . 85%. The other is the light-weighted and compact The pressure ratio is 25, compressor isentropic efficiency is 84%, and turbine isentropic efficiency is 86%. Ans: e. 126. Mechanical efficiency of gas turbines as compared to I.C engines is (a) higher (b) lower (c) same (d) depends on on odier considerations (e) unpredictable. Thus the decrease in compressor isentropic efficiency with pressure ratio is observed as shown in Fig. Consider the T-s diagram shown in thefollowing figure:Actual compression process in gasturbines is indicated by the process. In an ideal world, the value of the efficiency would be 1.0; in reality, it is always less than 1.0. Ans: b. Thus ideal gas equation can be rewritten asv/T = mR/p = constant Thus,T2/T1 = v2/v1 That is,T2/(27+273) = 2× v1/v1 T2=2×300T2= 600 k. 1234567891011121314. Advantages and Disadvantages of closed cycle. Ans: a; The ratio of specific weighf/h.p. η T = 5200 x (1190 – 839) x 0.91 = 1.661 MJ/kg Assertion (A): Gas turbines use very high air fuel ratio. View Answer Discuss. Low grade fuel can't be burnt in gas turbine since it leads to poor life of turbine blades, etc. ratio and high thermal efficiency has placed them at advantage over the heavy-duty gas turbine generators. Comparison Between Disc Brake & Drum Brake, TOM, Mechanical Engineering, GATE, Syllabus - Mechanical Engineering : ME, GATE, What is Cams & Followers, TOM, Mechanical Engineering, GATE, Mechanical Properties of Engineering Materials. β 2 = 90 o. B 4 :1 . Isentropic efficiency of the steam turbine: The isentropic efficiency of an optimized steam turbine is 90% for an advanced power plant. The turbine used in gas turbine power plant is larger than that used in steam power plants. ⇒ The thermal efficiency of a gas turbine as compared to a diesel plant is same more less depends on other factors ⇒ Pick up the correct statement gas turbine uses low air-fuel ratio to economies on fuel gas turbine uses high air-fuel ratio to reduce outgoing temperature gas turbine uses low air-fuel ratio to develop the high thrust required Two constant volume process and two constant pressure process, B. of gas turbin and I.C engines may be typically of the order of (a) 1 : 1 (b) 2 : 1 (c) 4 : 1 (d) 1:2 (e) 1 : 6. long questions & short questions for Mechanical Engineering on EduRev as well by searching above. Ans: a 123. 2. Consider the following statements in respect of gas turbines: 1. B. Reheating . Supersonic flow leads to decrease in flow rate.Which of the statements given above is/are correct? B. Gas turbine mcq, mcqs on gas Turbine, multiple choice questions gas turbine turbine, ... Two constant pressure process and two isentropic process . . η T = 5200 x (1190 – 839) x 0.91 = 1.661 MJ/kg In this mechanical engineering lecture today we learned about power  plant subjects Mcq on Gas turbine (objectives questions and answers). Hello friends my name is Roshan Namdeo Waje and founder of mechstudy.here I shere the imforfation about mechanical engineering. Heat drop in the moving blades to the heat drop in the fixed blades. Compressors, Gas Turbines & Jet Engines MCQ with detailed explanation for interview, entrance and competitive exams. Which one of the thermodynamic cycles shown in the following figures represents that of Brayton cycle? The solved questions answers in this Gas Turbine - MCQ Test 1 quiz give you a good mix of easy questions and tough questions. Efficiency of gas turbine is increased by using..... A. Inter cooling . Jan 13,2021 - Gas Turbine - MCQ Test 1 | 20 Questions MCQ Test has questions of Mechanical Engineering preparation. The thermal efficiency of a gas turbine as compared to a diesel plant is (a) same (b) more (c) less (d) depends on other factors (e) unpredictably. Q23 A gas turbine power plant working on Brayton cycle as per the following specifications Pressure and temperature of air at inlet to compressor = 1 bar and 10°C Power output of the plant = 15 MW Temperature at inlet to the turbine = 780°C Pressure ratio = 12 Isentropic efficiency of compressor = 100% Isentropic efficiency of turbine = 97% Determine the following: 0 Pressure and temperatures at … •Isentropic efficiency of the turbine is defined in a manner similar to that of the compressor. The overall isothermal efficiency of the compressor is defined as the ratio of Fig. Reason (R): The allowable maximum temperature at the turbine inlet is limited by available material considerations. Ans: e 124. D 9 : 1 . Mechanical efficiency of gas turbines as compared to I.C engines is (a) higher (b) lower (c) same (d) depends on on odier considerations (e) unpredictable. Isentropic efficiencies of both the HP and LP turbines, Thermal efficiency of the steam circuit; B) The compression ratio in the gas turbine cycle is 7.21 and the outlet gas temperature is 553 o C; assuming no pressure losses, calculate: isentropic efficiency of the compressor and turbine, the thermal efficiency of the gas turbine cycle. Ans: e Almost any kind of fuel can be used with gas turbines. Which of the above statements is/are correct? This mock test of Gas Turbine - MCQ Test 1 for Mechanical Engineering helps you for every Mechanical Engineering entrance exam. Supersonic flow leads to decrease in efficiency. Gas turbines are simple, compact and light in weight. The energy efficiency of the overall system changes from 26.6% to 34.1% as the isentropic efficiencies of the turbines varies from 50% to 90%. Isentropic compression of saturated vapour of all superheated vapour. A steam plant has the boiler efficiency of 92%, turbine efficiency (mechanical) of 94%, generator efficiency of 95% and cycle efficiency of44%. The compressor is divided into low-pressure and high-pressure stages. 7. Compressors, Gas Turbines and Jet Engines Compressors, Gas Turbines and Jet Engines. Reason (R): As the   compression   ratio    of   compressor  increases, the   range    oftemperature in the regenerator decreases and the amount of heat recovered reduces. In Rankine cycle the work output from the turbine is given by (a) change of internal energy between inlet and outlet ... B Increase in thermal efficiency but decrease in net output . 2. The isentropic efficiency of turbine can then be written as η T (h 2a - h 1)/(h 2s - h 1) where h 1 = enthalpy at the inlet h 2a = enthalpy of actual process at the exit h 2s = enthalpy of isentropic process at the exit : Isentropic Efficiency of Compressors and Pumps The turbine used in gas turbine power plants is smaller than that used in steam power plants. Assertion (A): The thermal efficiency of a gas turbine plant is low as compared tothat of reciprocating IC engines. Consider the following statements comparing I.C. The work done by gas turbine in isentropic process is then: W T,s = c p (T 3 – T 4s) = 5200 x (1190 – 839) = 1.825 MJ/kg. The pressure ratio in gas turbines is of the order of (a),2:l (b)4:1 (c) 61: 1 Which of the statements given above are correct? Efficiency of the Brayton cycle is lower than the efficiency of the Otto cycle, for the same compression ratio c. Efficiency of the Brayton cycle is same as that of the Otto cycle, for the same compression ratio d. cannot say You can find other Gas Turbine - MCQ Test 1 extra questions, Gas turbine plants are heavier and larger in size than steam turbineplants, 3. Methods to improve thermal efficiency. Maximum efficiency but very less specific work output, Maximum efficiency and very high specific work output, Minimum efficiency and very less specific work output, Minimum efficiency but very high specific work output ​. engines and gasturbines: 1. Pressure and temperature of air at inlet to compressor = 1… A gas turbine works on which one of the following cycles? The turbine on the left is an isentropic turbine. SJ J W K ( 1)/ 01 02 01 02 1 1 Ideal work of expansion for given pressure ratio The isentropic eﬃciency of the turbine is 85%. The real work done by gas turbine in adiabatic process is then: W T,real = c p (T 3 – T 4s) . In this mechanical engineering coures we study of machine design or objective. A gas turbine with air as the working fluid has an isentropic efficiency of 0.70 when operating at a pressure ratio of 3. Both A and R are individually true and R is the correct explanation of A, Both A and R are individually true but R is not the correct explanation of A. The compression ratio of a gas power plant cycle corresponding to maximum work output for the given temperature limits of Tmin and Tmax will be. The ratio of isentropic work to euler’s work is known as _____? The air-fuel ratio in gas turbines is of the order of (a) 7 : 1 (b) 15 : 1 (c) 30 : 1 (d) 40 : 1 (e) 50: 1. Learn Compressors, Gas Turbines And Jet Engines MCQ questions & answers are available for a Mechanical Engineering students to clear GATE exams, various technical interview, competitive examination, and another entrance exam. 2. The operating characteristics of the turbine are modeled by developing a multiple regression curve fit for the turbine efficiency as function of non-dimensional speed and pressure ratio. of gas turbin and I.C engines may be typically of the order of (a) 1 : 1 (b) 2 : 1 (c) 4 : 1 (d) 1:2 (e) 1 : 6. 4. students definitely take this Gas Turbine - MCQ Test 1 exercise for a better result in the exam. By continuing, I agree that I am at least 13 years old and have read and agree to the. (10), and the definition of turbine isentropic efficiency, Eq. 3. 12. Modern Combined Cycle Gas Turbine (CCGT) plants, in which the thermodynamic cycle of consists of two power plant cycles (e.g. One for heavy-duty gas turbines designed for land-based applications found in large combined cycle power plants. Heat drop in the fixed blades to the heat drop in the moving blades. Curve 1-3 is actual compression process in gas turbine. Ans: c. 125. 2. 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