List of top Thermodynamics and Marine Engineering Questions

A closed system is undergoing a reversible process 1–P–2 from state 1 to 2, as shown in the figure, where X and Y are thermodynamic properties. An irreversible process 2–Q–1 brings the system back from 2 to 1. The net change in entropy of the system and surroundings during the above-mentioned cycle are _______ respectively.

Consider a weightless, frictionless piston with a 2 kg mass placed on it as shown in the figure. At equilibrium in position 1, the cylinder contains 0.1 kg of air. The piston cross-sectional area is 0.01 m². The ambient pressure in the surroundings outside the piston-cylinder arrangement is 0 bar (absolute). When the mass above the piston is removed instantaneously, it moves up and hits the stop at position 2, which is 0.1 m above the initial position.
Assuming \( g = 9.81 \, {m/s}^2 \), the thermodynamic work done by the system during this process is ________ J (answer in integer).

Consider the psychrometric process denoted by the straight line from state 1 to 2 in the figure. The specific humidity, Dry Bulb Temperature (DBT), and Wet Bulb Temperature (WBT) at the two states are shown in the table. The latent heat of vaporization of water \( h_{fg} = 2440 \, {kJ/kg} \). If the flow rate of air is 1 kg/s, the rate of heat transfer from the air is _________ kW (rounded off to two decimal places).

Water of density \( \rho = 1000 \, {kg/m}^3 \) flows with a velocity \( V = 50 \, {m/s} \) through a 180° curved tube of uniform cross-section as shown in the figure. If the flow rate is \( 0.06 \, {m}^3/{s} \), the magnitude of the reaction force \( F_x \) required to keep it stationary is ________ kN (rounded off to one decimal place).

A tank with a constant water level of 4 m above the centreline of an opening of diameter 100 mm is shown in the figure. Neglect all losses and assume \( g = 9.81 \, {m/s}^2 \). The discharge through the opening is ________ litres/s (answer in integer).

An ideal Brayton cycle (1–2–3–4) consisting of two isentropic and two isobaric processes is shown in the \(T\)–\(s\) plot, where \(T\) is the temperature and \(s\) is the specific entropy of the system. Which one of the following plots represents the corresponding actual cycle \(1{–}2'{–}3{–}4'\) (denoted by dashed lines) between the same two pressures \(p_1\) and \(p_2\)?