There is a one and a half meter in height, two meter wide flat-plate solar collector at an angle of thirty seven degrees from the horizontal is exposed to the calm ambient air. The temperature of the collector glass cover is measured to be forty six degrees on a calm day when the surrounding air temperature is twenty five degrees Celsius. The effective sky temperature for radiation exchange between the glass cover and the open sky is -43 degrees. The glass has an emissivity of 0.92 and transmits 90% of the incident radiation. The water ow rate entering the piping system attached to the absorber at a 1.35 kg/min.

The solar radiation energy incident on the collector at a rate of 720 W/m2. Assuming the back surface of the absorber plate to be insulated and the only heat loss occurs through the glass cover, calculate:

1. The total rate of heat loss from the collector.

2. The collector efficiency, which is calculated as the ration of the heat energy absorbed by

the water and the solar energy incident on the collector.

3. The water temperature difference as it flows through the collector.