If carbon dioxide is cooled at I atm. it condenses directly to a solid (dry ice) at —78.4°C. The heat of sublimation at this temperature is ΔH sub (–78.4°C) = 6030 cal/mol.

(a) Calculate the heat removal rate (kW) required to produce 300 kg/h of dry ice at 1 atm and —78.4°C if CO2 (v) at 20°C is the feed.

(b) Suppose the process is carried out at 9.9 atm instead of 1 atm with the same initial and final temperatures. Referring to Figure 6.1-lb on p. 241, write an expression for the required heat removal rate in terms of heat capacities and latent heats of CO2 in different phases.