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GATE Past Year Questions: Availability & Irreversibility | Thermodynamics - Mechanical Engineering PDF Download

Q1: The Clausius inequality holds good for  [GATE ME 2022, SET-1]
(a) any process
(b) any cycle
(c) only reversible process
(d) only reversible cycle
Ans:
(b)
The Clausius inequality holds good for any cycle.
GATE Past Year Questions: Availability & Irreversibility | Thermodynamics - Mechanical Engineering= 0 ⇒ Reversible cycle
GATE Past Year Questions: Availability & Irreversibility | Thermodynamics - Mechanical Engineering< 0⇒ Irreversible cycle
GATE Past Year Questions: Availability & Irreversibility | Thermodynamics - Mechanical Engineering>0⇒ Impossible cycle

Q1: Keeping all other parameters identical, the Compression Ratio (CR) of an air standard diesel cycle is increased from 15 to 21. Take ratio of specific heats = 1.3 and cut-off ratio of the cycle r= 2
The difference between the new and the old efficiency values, in percentage,
new|CR = 21) - (
ηold |CR = 15) =  _______ %. (round off to one decimal place)  [GATE ME 2020, SET-2]
Ans: (4.6 to 4.9)
GATE Past Year Questions: Availability & Irreversibility | Thermodynamics - Mechanical Engineering

GATE Past Year Questions: Availability & Irreversibility | Thermodynamics - Mechanical Engineering = 4.8%

Question for GATE Past Year Questions: Availability & Irreversibility
Try yourself:A heat reservoir at 900 K is brought into contact with the ambient at 300 K for a short time. During this period 9000 kJ of heat is lost by the heat reservoir. The total loss in availability due to this process is

[1995]

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Question for GATE Past Year Questions: Availability & Irreversibility
Try yourself:Availability of a system at any given state is

[2000]

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Question for GATE Past Year Questions: Availability & Irreversibility
Try yourself:Considering the relationship TdS = dU + pdV between the entropy (S), internal energy (U), pressure (p), temperature (T) and volume (V), which of the following statements is correct?

[2003]

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Question for GATE Past Year Questions: Availability & Irreversibility
Try yourself:A steel billet of 2000 kg mass is to be cooled from 1250 K to 450 K. The heat released during this process is to be used as a source of energy. The ambient temperature is 303 K and specific heat of steel is 0.5 kJ/kgK. The available energy of this billet is

[2004]

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Question for GATE Past Year Questions: Availability & Irreversibility
Try yourself:The pressure, temperature and velocity of air flowing in pipe are 5 bar, 500 K and 50 m/s, respectively. The specific heats of air at a constant pressure and at constant volume are 1.005 kJ/kgK and 0.718 kJ/kgK, respectively.Neglect potential energy. If the pressure and temperature of the surroundings are 1 bar and 300 K, respectively, the available energy in kJ/ kg of the air stream is

[2013]

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Question for GATE Past Year Questions: Availability & Irreversibility
Try yourself:The maximum theoretical work obtainable, when a system interacts to equilibrium with a reference environment, is called

[2014]

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The document GATE Past Year Questions: Availability & Irreversibility | Thermodynamics - Mechanical Engineering is a part of the Mechanical Engineering Course Thermodynamics.
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FAQs on GATE Past Year Questions: Availability & Irreversibility - Thermodynamics - Mechanical Engineering

1. What is the concept of availability in thermodynamics?
Ans.Availability refers to the maximum useful work that can be obtained from a system when it is brought to equilibrium with its surroundings. It is a measure of the potential of a system to do work and is influenced by the system's state and the conditions of its environment.
2. How is irreversibility defined in mechanical engineering?
Ans.Irreversibility in mechanical engineering refers to processes that cannot be reversed without leaving changes in the surroundings. It is associated with energy dissipation, such as friction, turbulence, and non-ideal gas behavior, leading to a loss of available energy.
3. What are the main factors that contribute to irreversibility in thermodynamic processes?
Ans.Main factors contributing to irreversibility include frictional losses, heat transfer across finite temperature differences, mixing of different substances, and inelastic deformation. These factors lead to energy dissipation, reducing the system's ability to perform work.
4. How can the concept of availability be applied in engineering design?
Ans.Availability can be applied in engineering design by optimizing systems to minimize energy losses and maximize the useful work output. Designers can use this principle to enhance the efficiency of engines, refrigeration cycles, and power plants.
5. What is the relationship between availability and entropy?
Ans.The relationship between availability and entropy is that increased entropy within a system indicates a higher degree of irreversibility and a lower availability of energy for work. As entropy increases, the ability of a system to do useful work decreases, highlighting the importance of managing irreversibility in engineering applications.
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