First-Law Analysis for a Control Volume 此簡報可能會牽涉到聽眾的討論活動，也就是所謂的執行項目。因此在進行簡報時﹐可充份利用 PowerPoint 來記錄這些執行項目： 於投影片放映狀態按下滑鼠右鍵 選取〔會議記錄簿〕 選取〔執行項目〕 標籤 將出現的意見都記錄於此 按下〔確定〕以結束此對話方塊 在簡報進行到最後時﹐PowerPoint將會自動的建立一個執行項目投影片﹐並將你所記錄的內容顯示在該投影片上 Chapter 6 First-Law Analysis for a Control Volume
6.1 CONSERVATION OF MASS AND THE CONTROL VOLUME
Let us consider the conservation of mass law as it relates to the control volume. Rate of change = + in – out Continuity equation:
6.2 THE FIRST LAW OF THERMODYNAMICS FOR A CONTROL VOLUME 1st law for a control mass, ( rate equation for a process) (energy per unit mass at a state )
Rate of Flow Work 1 2
3 Delta=In-Out
6.3 THE STEADY-STATE PROCESS V
IN OUT
Application of Steady State
6.4 EXAMPLES OF STEADY-STATE PROCESSES superheated It is thought as a constant pressure process, even only a small pressure drop. No work is done by the control volume, i.e. Wcv is 0. Both kinetic and potential energy changes of the control volume are negligible
( No heat transfer across the control surface, but heat exchange happened insides. )
Solution 2
1 2 3 1 2 3
1 2
6.5 THE TRANSIENT PROCESS For example, filling closed tanks with a gas or liquid, or discharge from closed vessels is called transient process.
（1）
（2）
Example6.10
u2 P2
Example 6.12