Chemical Engineering GATE 2023 Questions with Answer

Ques 53 Heat Transfer

A slab of thickness 𝐿, as shown in the figure below, has cross-sectional area 𝐴 and constant thermal conductivity 𝑘. 𝑇₁ and 𝑇₂ are the temperatures at 𝑥=0 and x=𝐿, respectively. Which one of the following options is the CORRECT expression of the thermal resistance for steady-state one-dimensional heat conduction?

Ques 54 Heat Transfer

Given that 𝐸 (in W.m⁻²) is the total hemispherical emissive power of a surface maintained at a certain temperature, which of the following statements is/are CORRECT?

Ques 55 Heat Transfer

A fluid is flowing steadily under laminar conditions over a thin rectangular plate at temperature T_s as shown in the figure below. The velocity and temperature of the free stream are u_∞ and T_∞, respectively. When the fluid flow is only in the x-direction, h_x is the local heat transfer coefficient. Similarly, when the fluid flow is only in the y-direction, h_y is the corresponding local heat transfer coefficient. Use the correlation Nu = 0.332 (Re)^1/2 (Pr)^1/3 for the local heat transfer coefficient, where Nu, Re, and Pr are the appropriate Nusselt, Reynolds, and Prandtl numbers, respectively. The average heat transfer coefficients are defined as h̅_l = (1/l) ∫₀^l h_x dx and h̅_w = (1/w) ∫₀^w h_y dy. If w = 1 m and l = 4 m, the value of the ratio of h̅_w to h̅_l is _______ (in integer).

Ques 56 Heat Transfer

A perfectly insulated, concentric tube countercurrent heat exchanger is used to cool lubricating oil using water as a coolant (see figure below). Oil enters the outer annulus at a mass flow rate of 2 kg·s⁻¹ with a temperature of 100 °C and leaves at 40 °C. Water enters the inner tube at a mass flow rate of 1 kg·s⁻¹ with a temperature of 20 °C and leaves at 80 °C. Use specific heats of oil and water as 2089 J·kg⁻¹·K⁻¹ and 4178 J·kg⁻¹·K⁻¹, respectively. There is no phase change in both the streams. Under steady-state conditions, the number of transfer units (NTU) is _______ (in integer).

Ques 57 Mass Transfer

A packed distillation column, with vapor having an average molecular weight of 45 kg.kmol⁻¹, density of 2 kg.m⁻³ and a molar flow rate of 0.1 kmol.s⁻¹, has a flooding velocity of 0.15 m.s⁻¹. The column is designed to operate at 60% of the flooding velocity. Which one of the following is the CORRECT value for the column diameter (in m)?

Ques 58 Mass Transfer

A liquid L containing a dissolved gas S is stripped in a countercurrent operation using a pure carrier gas V. The liquid phase inlet and outlet mole fractions of S are 0.1 and 0.01, respectively. The equilibrium distribution of S between V and L is governed by y_e = x_e, where y_e and x_e are the mole fractions of S in V and L, respectively. The molar feed rate of the carrier gas stream is twice as that of the liquid stream. Under dilute solution conditions, the minimum number of ideal stages required is __________ (in integer).

Ques 59 Mass Transfer

In a binary gas-liquid system, N_A,EMD is the molar flux of a gas A for equimolar counter diffusion with a liquid B. N_A,UMD is the molar flux of A for steady one-component diffusion through stagnant B. Using the mole fraction of A in the bulk of the gas phase as 0.2 and that at the gas-liquid interface as 0.1 for both the modes of diffusion, the ratio of N_A,UMD to N_A,EMD is equal to ______ (rounded off to two decimal places).

Ques 60 Mass Transfer

Which one of the following represents the CORRECT effects of concentration polarization in a reverse osmosis process?

Ques 61 Mass Transfer

Partially saturated air at 1 bar and 50 °C is contacted with water in an adiabatic saturator. The air is cooled and humidified to saturation, and exits at 25 °C with an absolute humidity of 0.02 kg water per kg dry air. Use latent heat of vaporization of water as 2450 kJ·kg⁻¹, and average specific heat capacity for dry air and water, respectively, as 1.01 kJ·kg⁻¹·K⁻¹ and 4.18 kJ·kg⁻¹·K⁻¹. If the absolute humidity of air entering the adiabatic saturator is 𝓗 × 10⁻³ kg water per kg dry air, the value of 𝓗 is __________ (rounded off to two decimal places).

Ques 62 Mass Transfer

Distillation of a non-reactive binary mixture with components 𝐴 and 𝐵 is carried out in a batch still as shown in the figure below. The initial charge of the mixture in the still is 1 kmol. The initial and final amounts of 𝐴 in the still are 0.1 kmol and 0.01 kmol, respectively. Use a constant relative volatility of 4.5. The mole fraction of 𝐵 remaining in the vessel is _______ (rounded off to three decimal places).

Ques 63 Thermodynamics

John and Jane independently performed a thermodynamic experiment, in which X and Y represent the initial and final thermodynamic states of the system, respectively. John performed the experiment under reversible conditions, for which the change in entropy of the system was 𝚫𝑺_𝒓𝒆𝒗 . Jane performed the experiment under irreversible conditions, for which the change in entropy of the system was 𝚫𝑺_𝒊𝒓𝒓 . Which one of the following relationships is CORRECT?

Ques 64 Thermodynamics

Consider a system where a Carnot engine is operating between a source and a sink. Which of the following statements about this system is/are NOT correct?