transport phenomena 2

4. Consider the timed drug release pill shown in the figure below. The pill is ingested into the stomach. The pill is a slab of 0.36cm per side, which has an array of 16 cylindrical pores in it. Each pore is 0.4mm(0.04cm) in diameter and 2.0 mm(0.20cm) deep. Pure solid drug (species A) is loaded into each pore to a depth of 1.2mm(0.12cm), which provides a total initial drug loading of 2.65mg in all of the pores. The density of the solid drug ( (danblif) is 1.10g/cm. The drug dissolves into fluid inside the stomach, which approximates the properties of water (species B ). The maximum solubility of drug in water is 2.010gmol/cm ' (not very soluble), and the diffusion coefficient of the drug in the fluid is 2.0105cm/s at body temperature of 37C. The molecular weight of the drug is 120g/gmole, a. Determine the total transfer rate of the drug from the whole pill (Wi) to the body at when each 0.2cm pore is filled to a depth of 0.12cm with solid drug. You may assume that (1) the diffusion process is at a pseudo-steadystate, (2) the stomach fluid serves as an infinite sink for the drug so that c:%40, and (3) the drug does not chemically degrade inside the pore. List all other assumptions you make as appropriate in the development of your mass-transfer model. b. How long will it take (in hours) for all of the drug material in the reservoir to be released? c. Propose adjustment of one of the variables in the process that will increase the required time in part (b) by a factor