the mass and heat streams are represented by black
solid lines and red dashed lines, respectively, while the power
input/output streams are represented by magenta solid lines. The
heat streams S1 accounts for the heat leakage of the battery during
cycles, S4 for the heat stored in TSU during the discharge cycle,
S17 for the heat supplied by TSU for the charge cycle, and
finally
QCA for the heat demand by the charge cycle, or heat released by
the discharge cycle. The power terms PA represent the power
output from the discharge cycle and input for the charge cycle,
respectively.