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From page 43... ... 43 cargo hold is unventilated, then the void volume‡ and maximum flight duration (perhaps based on the amount of fuel loaded on the plane) must be estimated in order to verify that the concentration limit established in Step 1 is not exceeded during the flight. Read the entire page →
From page 44... ... 44 4. Estimate the total surface area of the dry ice packages that would produce a concentration in the free volume of the cargo compartment that equals the concentration limit used in Step 1. Read the entire page →
From page 45... ... 45 CO2Limit = carbon dioxide ceiling concentration, ppm, CO2In = carbon dioxide concentration in the incoming air‡, ppm, rCO2 = density of carbon dioxide, kg/m3, DT = the temperature difference between the dry ice and the external environment, 100 K, SubNum = sublimation number, dimensionless, tinsul = insulation thickness, suggest 0.038 m, and ldryice = heat of sublimation of dry ice, 573 kJ/kg. For an unventilated compartment: PkgArea CO CO Vol unvent Limit In compart : • = −2 2 106 ment COVoidFrac SubRate FlightTime i • • ρ 2 where the variables are same as the previous equation, except for: Volcompartment = compartment volume, m3, VoidFrac = fraction of compartment not occupied by cargo, dimensionless, SubRate = area-based sublimation rate, kg/m2 ? Read the entire page →
From page 46... ... 46 Dimension and Area Data Basing the estimated sublimation rate on dimensional area should be feasible. Major freight carriers already collect package dimensions from customers in order to calculate a dimension weight, which is then compared with the actual weight to determine the shipping charge. Read the entire page →
From page 47... ... 47 tion,† a 1-hour maximum flight time, a 50% void volume, a 5,000-ppm concentration limit,‡ and a sublimation rate of 250 g/m2 ? hr, the total surface area of dry ice packaging that could be placed in that cargo compartment would be 0.24 m2. Read the entire page →

From page 43...

... 43 cargo hold is unventilated, then the void volume‡ and maximum flight duration (perhaps based on the amount of fuel loaded on the plane) must be estimated in order to verify that the concentration limit established in Step 1 is not exceeded during the flight.

Read the entire page →

From page 44...

... 44 4. Estimate the total surface area of the dry ice packages that would produce a concentration in the free volume of the cargo compartment that equals the concentration limit used in Step 1.

Read the entire page →

From page 45...

... 45 CO2Limit = carbon dioxide ceiling concentration, ppm, CO2In = carbon dioxide concentration in the incoming air‡, ppm, rCO2 = density of carbon dioxide, kg/m3, DT = the temperature difference between the dry ice and the external environment, 100 K, SubNum = sublimation number, dimensionless, tinsul = insulation thickness, suggest 0.038 m, and ldryice = heat of sublimation of dry ice, 573 kJ/kg. For an unventilated compartment: PkgArea CO CO Vol unvent Limit In compart : • = −2 2 106 ment COVoidFrac SubRate FlightTime i • • ρ 2 where the variables are same as the previous equation, except for: Volcompartment = compartment volume, m3, VoidFrac = fraction of compartment not occupied by cargo, dimensionless, SubRate = area-based sublimation rate, kg/m2 ?

Read the entire page →

From page 46...

... 46 Dimension and Area Data Basing the estimated sublimation rate on dimensional area should be feasible. Major freight carriers already collect package dimensions from customers in order to calculate a dimension weight, which is then compared with the actual weight to determine the shipping charge.

Read the entire page →

From page 47...

... 47 tion,† a 1-hour maximum flight time, a 50% void volume, a 5,000-ppm concentration limit,‡ and a sublimation rate of 250 g/m2 ? hr, the total surface area of dry ice packaging that could be placed in that cargo compartment would be 0.24 m2.

Read the entire page →

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