Tham khảo tài liệu 'advanced gas turbine cycles episode 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 18 Advanced gas turbine cycles from Eq. . Thus the work lost due to internal irreversibility within the control volume when heat transfer takes place is still T as when the heat transfer is limited to exchange with the environment. The actual work output in a real irreversible process between stable states X and Y is therefore Wcv x Wcv revJx CR Bx - By - -1CR Ex-Ey- Eout - CR where Eg T A de is the work potential sometimes called the thermal energy of the heat rejected. The above analysis has been concerned with heat transfer from the control volume. Consider next heat d d REv x transferred to the control volume. Then that heat could be reversibly pumped to cv at temperature T from the atmosphere at temperature To by a reversed Carnot engine. This would require work input We REvlx ỹ- ộdổREV Under this new arrangement. Eq. for the reversible work delivered from cv would become Wcv revJx Ex Ey - 2rev and Eq. for the work output from the actual process would be Wcvlx Ex - Ey EfN - CR where E I is the work potential or thermal energy of the heat supplied to cv If heat were both transferred to and rejected from cv then a combination of Eqs. and would give Wcv x Ex - Ey 4 - Equt - R- Chapter 2. Reversibility and availability 19 . Exergy flux Eq. may be interpreted in terms of exergy flows work output and work potential Fig. . The equation may be rewritten as x W cvlx oUT- iN CR r. Thus the exergy Ex of the entering flow its capacity for producing work is translated into i the actual work output Wcvlx ii the work potential or thermal exergy of the heat rejected less than that of the heat supplied UT - n . iii the work lost due to internal irreversibility ZCR T0Á R iv the leaving exergy Ey. If the heat transferred from the control volume is not used externally to create work but is simply lost to the atmosphere in which further entropy is created then Equt can be sa d to be equal to qVT a lost work term .
