List of top Mechanical Engineering Questions on Thermodynamics

In a CI engine, the delay period in the combustion process mainly corresponds to
A balloon containing an ideal gas is initially kept in an evacuated and insulated room. If the balloon ruptures and the gas fills the entire room, what is the correct statement at the end of the process?
The maximum amount of low grade energy, which is convertible into work is known as
The whirl component of turbine blades is zero for the following turbine.
A single stage impulse turbine with a diameter of 1.2 m runs at 3000 rpm. If the blade speed ratio is 0.42, the inlet velocity of steam will be (in $\text{ms}^{-1}$)
If regenerator is added to a Brayton cycle, the thermal efficiency is improved due to
The refrigerant and absorbent used in Vapour absorption refrigeration system respectively are
Generally, in spark ignition engines, the compression ratio cannot be enhanced beyond certain limit because to avoid
In an ideal Brayton power cycle operated for the gas turbine plant, if \(T_1\) is the minimum temperature, \(T_3\) is the maximum temperature and pressure ratio is \(r_p\), then the net work ratio is given as
An air conditioning system mixes 30% fresh air at 35 $^\circ$C DBT and 50% RH with 70% recirculated air at 35 $^\circ$C DBT and 50% RH. Which of the following statements about "mixed air condition" is true?
Based on second law of thermodynamics the loss in available energy is being quantified as
The clearance is provided in the reciprocating compressor with clearance ratio of `k'. If the pressure ratio is \(\frac{P_2}{P_1}\), then the volumetric efficiency in terms of clearance ratio k, is
In an axial flow compressor, if the air stream is not able to follow the blade contour such phenomena is known as
If a substance is perfect crystal and existing at absolute zero K, then the specific entropy of the substance is
In a combined cycle for power generation, if the topping cycle has an efficiency of 45% and for bottoming cycle 30%, then the combined efficiency of the cycle is
A real gas undergoes throttling from 50 bar to 10 bar from an initial temperature of 300 K. If \(\mu_{JT} = -0.05 \text{ K/bar}\) for the initial condition, what is the approximate value of the exit temperature?
A mixture of gas expands from \(0.03 \text{ m}^3\) to \(0.06 \text{ m}^3\) at a constant pressure of 1 MPa and absorbs 84 kJ of heat during the process. The change in internal energy of the mixture is
Two reversible heat engines are operated with same heat input and heat output. One of the engine is operated between the temperature limits of \(T_2\) and 200 K & another is between 800 K and \(T_2\). Then the value of \(T_2\) is
Gas contained in a closed system consisting of a piston-cylinder arrangement is expanded. Work done by the gas during expansion is 50 kJ. The decrease in internal energy of the gas during expansion is 30 kJ. The heat transfer during the process is equal to:
Match List-I with List-II
List-IList-II
(A) Work done in a polytropic process(IV) \( \frac{p_1 V_1 - p_2 V_2}{n - 1} \)
(B) Work done in a steady flow process(I) \( - \int v \, dp \)
(C) Heat transfer in a reversible adiabatic process(II) Zero
(D) Work done in an isentropic process(III) \( \frac{p_1 V_1 - p_2 V_2}{\gamma - 1} \)
Choose the correct answer from the options given below:
In a psychrometric chart, what does a vertical downward line represent?
An aeroplane is flying at a height of 15 km, where the temperature is -50°C. Assuming \( k = 1.4 \) and \( R = 287 \, \text{J/K . kg} \), the approximate speed of the plane corresponding to \( M = 2.0 \) will be?
Which thermodynamics law predicts correctly the degree of completion of a chemical reaction?
Match List-I with List-II
List-I (Details of the processes of the cycle)List-II (Name of the cycle)
(A) Two adiabatic, one isobaric and two isochoric(I) Diesel
(B) Two adiabatic and two isochoric(II) Carnot
(C) Two adiabatic, one isobaric and one isochoric(III) Dual
(D) Two adiabatics and two isothermals(IV) Otto
Choose the correct answer from the options given below:
A refrigerating machine working on a reversed Carnot cycle takes out 2 kW of heat from the system while working between temperature limits of 300K and 200K. The coefficient of performance and power consumed by the cycle will be respectively: