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D2890-23 – Standard Test Method Technical Guide
📐 Scope and Significance
This standard test method, D2890-23, covers the calculation of liquid heat capacity of petroleum distillate fuels at atmospheric pressure. It is applicable for fuels where distillation data are obtained via Test Method D86 without decomposition up to 90% by volume distilled. The heat capacity is expressed in Btu/lb·°F (kJ/kg·K). The method is significant for engineering design, as the calculated values are similar to saturated liquid heat capacities in the required temperature-pressure range.
| 🎯 Parameter | ❄️ Limit |
|---|---|
| Lower Temperature Limit | 0 °F (−18 °C) |
| Upper Temperature Limit | 60 °F (16 °C) above VABP |
Note: The method is not applicable at temperatures less than 0 °F or greater than 60 °F above the volumetric average boiling point of the fuel.
⚙️ Data Requirements and Calculation Method
The key data required include distillation temperatures at 10%, 30%, 50%, 70%, and 90% by volume distilled from Test Method D86. These data are used to compute the volumetric average boiling point (VABP) and mean average boiling point (MeABP). The Watson characterization factor K is then determined from a graphical correlation, which classifies the crude oil based on its paraffinic or aromatic nature.
| 🟦 Volume Fraction Distilled | 📏 Temperature (from D86) |
|---|---|
| 10 % | °F |
| 30 % | °F |
| 50 % | °F |
| 70 % | °F |
| 90 % | °F |
Liquid heat capacity is obtained from correlations using temperature, API gravity (from Test Method D287), and K. The Watson characterization factor K of 12.5 or higher indicates paraffinic constituents, while 10 or lower indicates aromatic nature.
📊 Key Definitions and Terminology
Key terms defined in this standard include mean average boiling point (MeABP), volumetric average boiling point (VABP), and Watson characterization factor K. For other terms, refer to Terminology D4175. The method provides a systematic way to calculate heat capacity for engineering design.
Ensure that distillation data are obtained without reaching a decomposition point prior to 90% by volume distilled. This is critical for valid application of the method.
❓ Frequently Asked Questions
🔍 What is the Watson characterization factor K?
K is a systematic way of classifying crude oil according to its paraffinic, naphthenic, intermediate, or aromatic nature. A K of 12.5 or higher indicates paraffinic constituents, while 10 or lower indicates aromatic nature.
💡 What temperature range is applicable for this test method?
The method is applicable for temperatures between 0 °F and 60 °F above the volumetric average boiling point of the fuel.
⚡ What data is required from Test Method D86?
Distillation temperatures at 10%, 30%, 50%, 70%, and 90% by volume distilled are required.
📌 How is liquid heat capacity used in engineering?
Heat capacities obtained are at atmospheric pressure, but due to low temperature range, they are similar to saturated liquid heat capacities, making them useful for engineering design.