Simple Cooling and Dehumidifying Coil
By M.J. Brandemuehl
Revised for TRNSYS by N. Blair and R. Schwarz
This model was adapted strictly for use with the TRNSYS Program by
the Solar Energy Laboratory.
This subroutine calculates the outlet liquid temperature, air dry bulb
temperature and humidity ratio, and the total and sensible cooling capacity for
a cooling and dehumidifying coil. The algorithm accounts for the heat and mass
transfer associated with moisture condensation on the finned air-side surface of
the coil in accordance with ASHRAE methods. It determines whether the finned
surface is completely dry, completely wet, or partially wet and partially dry.
Simplifications in the algorithm involve the determination of overall heat
transfer coefficients for the coil and the modeling of operation with a
partially-wet fin surface. Overall heat transfer coefficients are determined
from the performance of the coil at a single rating point and assumed to be
constant at the other conditions. Part-wet coil performance calculations are
not performed. If part-wet conditions are indicated, the coil is assumed to be
either fully wet or fully dry, whichever gives the greatest total heat transfer
rate. Each algorithm assumes water flow in a counterflow crossflow heat
exchanger configuration and models the coil using equations for a counterflow
heat exchanger. The model is most appropriate for coils with four or more rows.
Sample input and output are included in the source code.
REF: A Toolkit for Secondary HVAC System Energy Calculations May 25,1992
Joint Center for Energy Management University of Colorado at Boulder