Miscellaneous utilities (ht.core)

ht.core.LMTD(Thi, Tho, Tci, Tco, counterflow=True)[source]

Returns the log-mean temperature difference of an ideal counterflow or co-current heat exchanger.

\[ \begin{align}\begin{aligned}\Delta T_{LMTD}=\frac{\Delta T_1-\Delta T_2}{\ln(\Delta T_1/\Delta T_2)}\\\begin{split}\text{For countercurrent: } \\ \Delta T_1=T_{h,i}-T_{c,o}\\ \Delta T_2=T_{h,o}-T_{c,i}\end{split}\\\begin{split}\text{Parallel Flow Only:} \\ {\Delta T_1=T_{h,i}-T_{c,i}}\\ {\Delta T_2=T_{h,o}-T_{c,o}}\end{split}\end{aligned}\end{align} \]
Parameters:

Thi : float

Inlet temperature of hot fluid, [K]

Tho : float

Outlet temperature of hot fluid, [K]

Tci : float

Inlet temperature of cold fluid, [K]

Tco : float

Outlet temperature of cold fluid, [K]

counterflow : bool, optional

Whether the exchanger is counterflow or co-current

Returns:

LMTD : float

Log-mean temperature difference [K]

Notes

Any consistent set of units produces a consistent output.

References

[R691691](1, 2) Bergman, Theodore L., Adrienne S. Lavine, Frank P. Incropera, and David P. DeWitt. Introduction to Heat Transfer. 6E. Hoboken, NJ: Wiley, 2011.

Examples

Example 11.1 in [R691691].

>>> LMTD(100., 60., 30., 40.2)
43.200409294131525
>>> LMTD(100., 60., 30., 40.2, counterflow=False)
39.75251118049003