4. Which of the statements given above are correct? a. Assertion (A): Gas turbines use very high air fuel ratio. Turbine performance •The flow in a turbine is also assumed to be adiabatic, though in actual engines there could be turbine blade cooling. Fig. So additional work is needed to overcome the inefficiency of the compressor to produce a desired CPR. Gas turbines are simple, compact and light in weight. 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. 2. 2. •Isentropic efficiency of the turbine is defined in a manner similar to that of the compressor. 2. 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 … A 2 : 1 . Reason (R): In a gas turbine plant, the maximum pressure and temperature arelow when compared to those of reciprocating IC engines. ⇒ 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 The degree of reaction of a reaction turbine is the ratio of energytransfer in fixed blade to the overall energy transfer across a stage. Which of the following is a types of gas turbine power plant ? Ans: c. 125. engines and not in gas turbines. Compressors, Gas Turbines And Jet Engines MCQ question is the important chapter for a Mechanical Engineering and GATE students. Thus the decrease in compressor isentropic efficiency with pressure ratio is observed as shown in Fig. 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. 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. Methods to improve thermal efficiency. Ch 8, Lesson C, Page 3 - Isentropic Efficiency of a Turbine. 7. 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. The compressor is divided into low-pressure and high-pressure stages. Complete expansion of working substance is possible in I.C. Gas turbine cycle (Brayton cycle) is not as efficient as Rankine cycle forsteam. SJ J W K ( 1)/ 01 02 01 02 1 1 Ideal work of expansion for given pressure ratio In this mechanical engineering lecture today we learned about power  plant subjects Mcq on Gas turbine (objectives questions and answers). β 2 = 90 o. The same turbine can be used for  both plants. (9), the isentropic temperature change, Eq. students definitely take this Gas Turbine - MCQ Test 1 exercise for a better result in the exam. Compressors, Gas Turbines & Jet Engines MCQ with detailed explanation for interview, entrance and competitive exams. ... A. compressor efficiency B. isentropic efficiency C. Euler’s efficiency D. pressure coefficient E. pressure ratio. 2. Which of the above statements is/are correct? 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. 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 ​. 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. Today we study of  multiple  choice questions (mcq) on f... Mcq on Gas Turbine (objectives questions and answers). Efficiency of the Brayton cycle is higher than the efficiency of the Otto cycle, for the same compression ratio b. 18. The heat losses are 15% of the calorific value. Almost any kind of fuel can be used with gas turbines. ConversionConversion Supersonic flow leads to decrease in flow rate.Which of the statements given above is/are correct? ... B Increase in thermal efficiency but decrease in net output . 2.11. 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 … The pressure ratio is 25, compressor isentropic efficiency is 84%, and turbine isentropic efficiency is 86%. In this mechanical engineering coures we study of machine design or objective. Ans: a 123. Compressors, Gas Turbines and Jet Engines Compressors, Gas Turbines and Jet Engines. Supersonic flow leads to decrease in efficiency. In this mechanical engineering coures we study of machine design objective. Ans: a; The ratio of specific weighf/h.p. The other is the light-weighted and compact 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. Conservatively, we took a value of 87% in our analyses. ratio and high thermal efficiency has placed them at advantage over the heavy-duty gas turbine generators. Read More Section(Compressors, Gas Turbines and Jet Engines) Each Section contains maximum 70 questions. 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. This mock test of Gas Turbine - MCQ Test 1 for Mechanical Engineering helps you for every Mechanical Engineering entrance exam. The maximum temperature at the inlet to the turbine is 800°C. Mechanical Engineering 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. Consider the following statements comparing I.C. Isentropic compression of saturated vapour of all superheated vapour. Mcq Added by: Muhammad Bilal Khattak. C 61 : 1 . This contains 20 Multiple Choice Questions for Mechanical Engineering Gas Turbine - MCQ Test 1 (mcq) to study with solutions a complete question bank. 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. 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%. (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. Which one of the thermodynamic cycles shown in the following figures represents that of Brayton cycle? View Answer Discuss. Assertion (A): The thermal efficiency of gas turbine plants is higher compared todiesel plants. 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. 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 In an ideal world, the value of the efficiency would be 1.0; in reality, it is always less than 1.0. 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%. Now, the pressure ratio of the turbine is increased to 5, while maintaining the same inlet conditions. Jet propulsion and Rocket propulsion. Today, there exist two large markets for industrial gas turbines. GAS TURBINES Unit 3: Gas Turbines and Jet Propulsion: Classification of Gas Turbines, Analysis of open cycle gas turbine cycle. The turbine on the left is an isentropic turbine. . 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. 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. In this mechanical engineering lecture today we learned about power  plant subjects. You can find other Gas Turbine - MCQ Test 1 extra questions, In Rankine cycle the work output from the turbine is given by (a) change of internal energy between inlet and outlet Gas turbines require 'cooling water for its operations, 4. It is compressed to 4 bar with an isentropic eﬃciency of 82%. 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. Efficiency of the feedwater pump: According to manufacturers informations, the overall efficiency of the feedwater pump can be 75-85% according to the size. 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. Solution for A gas turbine power plant working on Brayton cycle as per the following specifications. 1. A steam plant has the boiler efficiency of 92%, turbine efficiency (mechanical) of 94%, generator efficiency of 95% and cycle efficiency of44%. Ans: e 124. 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. 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. A gas turbine works on which one of the following cycles? EduRev is a knowledge-sharing community that depends on everyone being able to pitch in when they know something. The turbine used in gas turbine power plant is larger than that used in steam power plants. Consider the following statements in respect of gas turbines: 1. The efficiency factor is included to account for the actual performance of the compressor as opposed to the ideal, isentropic performance. 5 shows the effect of the isentropic efficiencies of turbine 1 and turbine 2 on the overall system energy and exergy efficiency. The solved questions answers in this Gas Turbine - MCQ Test 1 quiz give you a good mix of easy questions and tough questions. (11). relationships for the turbine work, Eq. Blade to gas speed ratio. Reason (R): The allowable maximum temperature at the turbine inlet is limited by available material considerations. Ans: e. 126. {\displaystyle \,\sigma _ {s}= {\frac {u_ {2}} {c_ {0}}}= [2 (1+\phi _ {2}\cot {\beta _ {2}})]^ {- {\frac {1} {2}}}} for. B 4 :1 . The pressure ratio in gas turbines is of the order of (a),2:l (b)4:1 (c) 61: 1 Gas turbine mcq, mcqs on gas Turbine, multiple choice questions gas turbine turbine, ... Two constant pressure process and two isentropic process . Ans: b. The power coefficient (cp)variation of a wind mill with the speed ratio is correctly shown by. 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 ratio of isentropic work to euler’s work is known as _____? Heat drop in the fixed blades to the heat drop in the moving blades. The ratio of specific weighf/h.p. engines and gasturbines: 1. Advantages and Disadvantages of closed cycle. The degree of reaction is defined as the ratio..... A. C. Heat drop in the moving blades to the total heat drop in the fixed blades. Reason (R): The mechanical efficiency of gas turbines is higher compared to dieselengines. One for heavy-duty gas turbines designed for land-based applications found in large combined cycle power plants. B. There is flexibility in the design of different components of gas turbines as different processes take place in different components. Jan 13,2021 - Gas Turbine - MCQ Test 1 | 20 Questions MCQ Test has questions of Mechanical Engineering preparation. Pressure and temperature of air at inlet to compressor = 1… please do not enter any spam link in the comment box Assertion (A): The thermal efficiency of a gas turbine plant is low as compared tothat of reciprocating IC engines. In a gas turbine plant air enters the compressor at 1 bar and 7°C. A gas turbine cycle with heat exchanger and reheating improves, Both thermal efficiency and specific power output, Neither thermal efficiency nor specific power output ​. B. Reheating . Curve 1-3 is actual compression process in gas turbine. In this mechanical engineering coures today  we solve of thermodynamics objective. Here are two turbines. η T = 5200 x (1190 – 839) x 0.91 = 1.661 MJ/kg The calorific value of the fuel used is 43.1 MJ/kg. Isentropic efficiency of the steam turbine: The isentropic efficiency of an optimized steam turbine is 90% for an advanced power plant. EmoticonEmoticon, A. The real work done by gas turbine in adiabatic process is then: W T,real = c p (T 3 – T 4s) . Consider the T-s diagram shown in thefollowing figure:Actual compression process in gasturbines is indicated by the process. 3. σ s = u 2 c 0 = [ 2 ( 1 + ϕ 2 cot ⁡ β 2 ) ] − 1 2. Two constant pressure process and two isentropic process, C. Two isobaric process and two isentropic process. The speed of rotation of the moving elements of gas turbines is muchhigher than those of steam turbines, 2. Even low grade fuels can be burnt in gas turbines.Of these statements. 12. Though A and R are true, but R is not correct reason for A. The blade-to-gas speed ratio can be expressed in terms of the isentropic stage terminal velocity c 0 . η T = 5200 x (1190 – 839) x 0.91 = 1.661 MJ/kg A large single-cycle gas turbine typically produces for example 300 megawatts of electric power and has 35–40% thermal efficiency. Heat drop in the moving blades to the heat drop in the fixed blades. 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 … The fuel used is 43.1 MJ/kg, it is compressed to 4 bar an. At least 13 years old and have read and agree to the Brayton cycle is higher compared to.. ; the ratio..... a value of 87 % in our analyses air is at 10°C and 100,! Questions ( MCQ ) on f... MCQ on gas turbine - MCQ 1! Efficient as Rankine cycle forsteam, intake air is at 10°C and 100 kPa and... 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