4.3.1. Boundary conditions for GPA

The velocity and temperature functions, for the three vertical planes considered (left, middle, and right), were the ones presented above. The air turbulence was specified using the turbulence intensity [12]:

$$I\_t = 0.16 \cdot \text{Re}\_{D\hbar}{}^{-0.125} \cdot 100. \tag{12}$$

Turbulence intensity at GPA exit had the following values: It = 2.66 (left plane); It = 1.83 (middle plane); It = 2.16 (right plane).

A boundary condition was also imposed for the lateral plane (0, Figure 23); here, air velocity was constant over the entire section (0.2 m/s), the flow was laminar, and air temperature was 25�C.

Figure 23. Measuring planes. 0, lateral plane, with air entering at 0.2 m/s; 1, left plane; 2, middle plane; 3, right plane.

Figure 24. Air velocity at the GPA level.

calculation is an iterative process, using the pressure-velocity coupling algorithm, in which the momentum and continuity equations, based on pressure, is solved simultaneously, and the

Figure 22. Placement of the sensors and the central data acquisition unit. a, placement of the temperature, humidity, and velocity sensors inside the cabinet; b, placement of the temperature, humidity, and velocity sensors at GPA grill; c, view of

The boundary conditions were imposed by the pre-processing program Gambit and completed with functions and values in the Fluent CFD simulation program [12]. The boundary conditions also took into account the conditions inside the climatic chamber (tenv = 25C, Φenv = 60%, vair = 0.2 m/s, according to EN-ISO 23953); as there are different boundary conditions for

The velocity and temperature functions, for the three vertical planes considered (left, middle, and right), were the ones presented above. The air turbulence was specified using the turbu-

terms referring to the pressure gradient and mass flow rate are discretized implicitly.

the horizontal grill (GPA) and base grill (GRA), these are presented separately.

4.3. Boundary conditions

the central data acquisition unit.

62 Refrigeration

4.3.1. Boundary conditions for GPA

lence intensity [12]:

Figure 25. Air temperature at the GPA level.

Figure 26. Air velocity profiles, after filtering, for the three vertical planes.
