The THROHPUT code provides a detailed model of the transient, thermohydraulic behavior of liquid metal heat pipes. Currently, it models homogeneous or composite wicks in a cylindrical heat pipe structure. The boundary conditions assumed are: a time-dependent heat input in the evaporator section, zero heat transfer at the outer wall in the adiabatic section, and radiative cooling to a specified ambient temperature in the condenser section. The user specifies the dimensions of the heat pipe and of the wick structure.
The THROHPUT code models the transport and exchange of all three phases of the working fluid (solid, liquid, and gas) and of a noncondensible gas. It considers axial and radial conduction, axial and radial convection, axial and radial phase change heat transfer (both evaporation/condensation and melting/freezing) and radiative heat transfer from the condenser section. It has a geometric model for the capillary pressure difference generated by the wick. To model all of these parameters, THROHPUT solves a system which consists of fifteen partial differential equations at each axial node. The associated algebraic system consequently has a block tridiagonal matrix structure with 15×15 blocks and a set of blocks for each node. The temporal scheme used is a fully-implicit scheme which iterates on the Jacobian matrix until convergence. A sophisticated time step control scheme is utilized.