Modeling and Design of Net ZEBs as Integrated Energy Systems - Modeling, Design, and Optimization of Net-Zero Energy Buildings - page 62

determine T ch . This is then employed to find the correct values of T PV and
T b , which are utilized to fine-tune the calculations. Considering an element
d x in the flow direction, we have
where the air flow rate is equal to .
The following ordinary differential equation is obtained:
where ; A ch is the average cross-section channel area (m 2 ); V ch is
the average air velocity in the channel (ms −1 ); W is the width of the air
channel (m); x is the coordinate in the fluid flow direction (m); and ρ is the
air density (kg m −3 ).
The air temperature variation inside a control volume can be calculated
using Eq. (2.34) once the inlet air temperature T in is known.
(2.34)
The PV and glazing or back side temperatures are obtained as
where . A roof or façade section may be split into a
number of control volumes in which the solution is applied to each
individual one where the outlet temperature of one control volume is the
inlet temperature for the next one.
2.2.2 Solar Thermal Systems
Solar thermal systems consist primarily of collectors, thermal storage tanks,
heat exchangers, and distribution systems. See Figure 2.11 for example.