IFPSC

Property Transferability Proposal

(PROBLEM TO BE ANNOUNCED AT THE 2006 AICHE ANNUAL MEETING)

Introduction

A researcher working in an industrial environment may be called on to predict a range of different properties. A method that is able to predict properties that were not used in the original parameterization may be more valuable in this situation than one which may provide more accurate results - but only for one property or property type.

Challenge

Demonstrate a model that is transferable to a variety of property types by predicting some or all of the properties listed below for BOTH:

1. the round-robin model
2. a model that you have developed

Properties (T1=? K)

Category 1 (100 points total)

1. saturated liquid phase at T1 (12 points max)

2. saturated vapor phase density at T1 (12 points max)

3. second virial coefficient at T1 (12 points max)

4. vapor pressure at T1 (12 points max)

5. heat of vaporization at T1 (12 points max)

6. normal boiling temperature at 1 atm (20 points max)

7. critical density and temperature (20 points max)

Category 2 (100 points total)

1. saturated liquid phase heat capacity (Cp) at T1 (15 points max)

2. saturated vapor phase heat capacity (Cp) at T1 (15 points max)

3. saturated liquid phase isothermal compressibility at T1 (20 points max)

4. saturated vapor phase isothermal compressibility at T1 (20 points max)

5. surface tension at T1 (30 points max)

Category 3 (100 points total)

1. saturated liquid phase viscosity at T1 (25 points max)

2. saturated vapor phase viscosity at T1 (25 points max)

3. saturated liquid phase thermal conductivity at T1 (25 points max)

4. saturated vapor phase thermal conductivity at T1 (25 points max)

Round-Robin Model

A literature model will be provided. Your calculations for the round-robin model will be used to establish the validity of your methods and also provide data on the variability of property predictions performed by different researchers on the same model (a round-robin experiment).

Awarding of Points

Points will be awarded based on comparison to experiment for each property that you predict with the model you developed. The experimental values will be provided at the time of the challenge announcement (that way no one has an advantage of being better at turning up experimental data).

The maximum number of points available for each property are specified above in the list of property categories.

For each property, a threshold maximum % deviation from the experimental benchmark data will be specified. Predictions with % deviation greater than this threshold will receive zero points.

For each property, an uncertainty in the benchmark data will be determined. Predictions with % deviation smaller than that represented by the uncertainty in the benchmark data will receive full credit (the maximum number of points available for that property).

For predictions falling between the benchmark value and the maximum allowed deviation, points will be awarded based on a pro-rated scale inversely proportional to the (or square of the ?) percent deviation.

Zero points will be awarded for the properties that you use to fit your model parameters.

A bonus of 50 points will be awarded if you score greater than zero points for at least one property in all 3 categories, since the purpose and spirit of this problem is to test transferability to a wide range of properties.

The entry with the highest points total is the Champion.

Additional Rules/Requirements

Any theory/modeling/simulation method may be used as long it complies with the rules and restrictions specified for the challenge problem. For example, non-force-field-based methods must comply with the spirit of the restrictions placed on force fields. This compliance will be evaluated by the judges on a case-by-case basis.

The same model must be used for all of the property calculations. For molecular simulations, this means that exactly the same force field parameters must be used for calculating all property predictions that you submit. For predictions that are not based on molecular simulations, compliance with the spirit of this criterion will be determined by the judges on a case-by-case basis.

Properties from only 1 the property categories may be used to adjust the model parameters (no restriction on temperature). You may not fit to any properties from another category (regardless of temperature). No points will be available for the properties used to adjust model parameters. Points will be available for other properties (even from the same category) that are not used to adjust model parameters.

The restriction on data that can be used to fit model parameters applies to all model parameters even if they were published in the open literature prior to the announcement of the challenge.

You do not have to submit predictions for all of the properties in a category. However, for each property you submit in a category, you must do so for both the round-robin model and your model.

If constant NVT simulations are performed, the density value used must be that which is calculated for your model. You may not arbitrarily use a (perhaps experimental) density. You must use the density that your model would predict. * Extrapolations of simulated data are acceptable for predicting the critical properties and normal boiling point. For example, the Clausius-Clapeyron equation is commonly used to calculate normal boiling points from simulation data at higher temperatures and the saturated density scaling law and the law of rectilinear diameters are commonly used to estimate critical properties from simulation data at sub-critical state points.

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