Anyone please help me to understand the similarity and difference between the terms "local gas void fraction" for Gas-Solid system and "local gas volume fraction" for Gas-Liquid system. Why we always use the term "local gas voidage" in case GS fluidized bed?, why not local gas volume fraction?
1. Void fraction inherently means gas void fraction. The term 'local void fraction' is a little strange because it simply can't be found. Only average values can be known.
2. In a gas-liquid system (the gas dispersed in the liquid), the gas volume fraction represents the volume occupied by bubbles. In (aggregatively fluidized) gas-solid fluidized beds, in addition to the gas in the bubbles, there is additionally the interstitial gas. But the void fraction that one determines by bed expansion studies after minimum fluidization is the bubble void fraction.
1. Void fraction inherently means gas void fraction. The term 'local void fraction' is a little strange because it simply can't be found. Only average values can be known.
2. In a gas-liquid system (the gas dispersed in the liquid), the gas volume fraction represents the volume occupied by bubbles. In (aggregatively fluidized) gas-solid fluidized beds, in addition to the gas in the bubbles, there is additionally the interstitial gas. But the void fraction that one determines by bed expansion studies after minimum fluidization is the bubble void fraction.
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