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Question 4.57: During a non-flow thermodynamic process the internal energy ...

During a non-flow thermodynamic process the internal energy possessed by the working fluid within the system was increased from 10 to 30 kJ while 40 kJ of work was done by the system.

What are the magnitude and direction of the heat energy transfer across the system during the process?

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Using Q − W = U_2 – U_1, where U_1=10 \ kJ , U_2=30 \ kJ and W = 40 kJ (positive work), Q − 40 = 30 − 10 and Q = 60 kJ.
Since Q is positive, it must be heat supplied to the system, which may be represented by an arrow pointing into the system, as shown in Figure 4.106.

 

ex 4-57 fig 4-106

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