PSI - Issue 47

Amani J. Majeed / Procedia Structural Integrity 47 (2023) 919–931 Amani J. Majeed / Structural Integrity Procedia 00 (2019) 000–000 �� 1158 � 1 � 0.066 cos � � 3 3 6 7 0 0 �� �� 0.175 � 1 � 0.2cos � 0.39 ��� 0.045 � 1 � cos � 195 �� Vary throughout the year because of seasonal changes.

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- Altitude angle of the sun ( β ) : it is the angle among direct solar radiation falling on the surface and its horizontal level (Duffie & Beckman, 1980); sin � �� cos � � cos � � cos � sin � � sin � � The sunrise and sunset times ( τ 1 and τ 2 ) is given by 1 � 12 � ��� �� �� ��������� ���� �� τ 2 � 12 � �� �� tan � � tan � �� 15 l : is the latitude angle, however the latitude of Oman is (24.7) Multiplying the amount of solar beam radiation with cosine of the angle of incidence gives the component of the vector of solar beam radiation: cos � � � � � � � � � � � � �� � � � � � � As a final step, it is important to define zenith angle so that angle of incidence can be calculated. Zenith angle corresponds to the angle formed by the sun line and the beam radiation (Duffie & Beckman, 1980; Patnode, 2006): cos � � �� cos � � cos � � cos �φ�� sin � � sin � � 3.2. Solar Irradiation Absorption in the Absorber Heat is transferred from the sun to the absorber through the glass envelope as shown in Fig. 2. The heat is reflected by the mirrors before falling on the absorber. Solar energy absorbed by the fluid is not fully transmitted. Heat is lost from the absorber to the glass-envelope. In addition, the heat is lost to the environment through the glass envelope.

Fig. 2. An element of heat collection with a heat transfer model