Some at plate solar collectors change their tilt angle throughout the day in order to intercept the maximum amount of the direct solar radiation. However, the tilt angle, measured from the horizontal, also reflects the rate of heat loss from the collector. Consider a 1.5 m high and 3 m wide solar collector that is tilted at an angle , as shown in Figure 4. The back side of the absorber is heavily insulated. The absorber plate and the glass cover, which are spaced 2.5 cm from each other, are maintained at temperatures of 80C and 40C, respectively. Determine the rate of heat loss from the absorber plate by natural convection when the plate is tilted at an angle of 30 from the horizontal.