A vertical array of circuit boards of 150-mm height is to be air cooled such that the board temperature does not exceed 60°C when the ambient temperature is 25°C.
Assuming isothermal surface conditions, determine the allowable electrical power dissipation per board for the cooling arrangements:
(a) Free convection only (no forced airflow).
(b) Airflow with a downward velocity of 0.6 m/s.
(c) Airflow with an upward velocity of 0.3 m/s.
(d) Airflow with a velocity (upward or downward) of 5 m/s.