the vortex area was less due to the relatively shorter length of H2 . Therefore , it was found that the arrangement of the baffles was more favorable than the number of the baffles in terms of pressure drop , and the longitudinal spacing of the baffles was the main factor of influence .
Table 3 . Pressure drop of air‐type PVT collector
Case |
dP [ Pa ] |
Case |
dP [ Pa ] |
Case |
dP [ Pa ] |
Case 1 |
7.99 |
Case 4 |
7.52 |
Case 7 |
9.21 |
Case 2 |
7.52 |
Case 5 |
7.25 |
Case 8 |
8.88 |
Case 3 |
6.78 |
Case 6 |
6.69 |
Case 9 |
8.85 |
Figure 5 is a graph showing the thermal efficiency and heat gain of the air‐type PVT collector with triangular baffles , for each Case . The thermal efficiency of the air‐type PVT collector can be calculated by Equation 1 , which was deduced by applying the collector ’ s flow rate and inlet / outlet temperature . Based on this analysis , the reference efficiency without baffles was 26.7 % and the heat gain was 287Wth . The thermal efficiency of the air‐type PVT collector with triangular baffles was 34.3 ‐35 %, and the heat gain was analyzed to be 369‐377Wth . The collectorʹs thermal efficiency was up to 13.5 % higher than that of the reference collector , and the heat gain was 89.4Wth . For Cases 1‐9 , high outlet temperature was obtained according to the baffle placement parameters , and the heat efficiency and heat gain of Case 3 were the highest .
Figure 5 . Thermal efficiency and heat gain by case of the air‐type PVT collector
η �� �� � �
� �
��� �� �� ���� ������ �� ����� � � ��� ��
( 1 )
AA ��� : Surface area of the collector ( m 2 ); G : Solar radiation ( W / m 2 ); mm� : Mass flow rate ( kg / h ); Cp : Specific heat of air at a constant pressure ( J / kg o C ); Toutlet : Outlet air temperature of PVT ( o C ); Tinlet : Inlet air temperature of PVT ( o C ); η �� : Thermal efficiency ( ‐ )
4 . Conclusions
In order to obtain a high air heat source , it is important for air‐type PVT collectors to keep the air flow inside the collector uniform . To improve the thermal performance of the air‐type PVT collector , this study analyzed the flow path characteristics inside the collector through CFD simulation by adjusting the installation conditions of the triangular baffles in the collector .
The thermal performance of the air‐type PVT collector was advantageously analyzed by the wider the W1 and the narrower the H2 . In addition , Case 3 , which has a more even arrangement of baffles ,
Comparative Analysis for Improvement Thermal Performance of Air-type PVT Collector with Triangular Baffles 368