Q1: A bed consists of particles of density 2000 kg/m³. If the height of the bed is 1.5 metres and its porosity 0.6, the pressure drop required to fluidise the bed by air is

ANS:B - 11.77 kPa

To calculate the pressure drop required to fluidize the bed by air, we can use the Ergun equation, which relates the pressure drop in a packed bed to the properties of the bed and the fluid. Given data:

• Density of particles (ρs\rho_sρs​) = 2000 kg/m³
• Height of the bed (HHH) = 1.5 m
• Porosity (ϵ\epsilonϵ) = 0.6

First, calculate the voidage (ϵv\epsilon_vϵv​): ϵv=1−ϵ=1−0.6=0.4\epsilon_v = 1 - \epsilon = 1 - 0.6 = 0.4ϵv​=1−ϵ=1−0.6=0.4 Now, use the Ergun equation for pressure drop ΔP\Delta PΔP across the bed: ΔP=150(1−ϵ)3.6μuϵ3dp2\Delta P = \frac{150 (1 - \epsilon)^{3.6} \mu u}{\epsilon^3 d_p^2}ΔP=ϵ3dp2​150(1−ϵ)3.6μu​ Where:

• μ\muμ = viscosity of air (at standard conditions, approximately 1.81×10−51.81 \times 10^{-5}1.81×10−5 Pa·s)
• uuu = superficial velocity of air (typically specified in m/s)
• dpd_pdp​ = particle diameter (assumed to be characteristic, but not given)
• ϵ\epsilonϵ = void fraction

Given the options and the typical approach in fluidization calculations, let's estimate the pressure drop. The correct answer isn't clear without additional data